Abstract

Reverse type-I core/shell quantum dots (QDs) have attracted much interest owing to their much more tunable emissions as compared with type-I QDs, thus benefiting full color display. However, the choices of the reverse type-I material are quite limited and their photoluminescence quantum yields (QYs) are still low, which restricts their further applications in optoelectronics. Here, we present the synthesis of highly bright CdxZn1-xS/CdSe reverse type-II QDs with a wide tunable emission ranging from 450 to 670 nm and a quantum yield of 61% at 638 nm. Two red quantum dot light-emitting diodes based on Cd0.1Zn0.9S/CdSe and CdSe/Cd0.1Zn0.9S have been fabricated to study the influence of energy level alignment on the device performances. The luminance and external quantum efficiency of the Cd0.1Zn0.9S/CdSe device (11412 cd/m2 and 8.23%) are much higher than that of CdSe/Cd0.1Zn0.9S one, despite its lower PL QY. Evidence shows that the reverse type-I structure benefits the charge injection into the emitting material without overcoming the large physical barrier of the outer shell, thus leading to notable improvements in device performances.

© 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

1. Introduction

Semiconductor quantum dots (QDs) are considered as promising materials for next generation optoelectronics [1–8], owing to their unique optical and electronic properties, including tunable emission wavelengths by controlling the size [9], narrow emission widths, high photoluminescence quantum yields [10], high charge carrier mobility and ease of solution processing [11]. Over the past decades, colloidal QDs have been widely investigated for display applications. QD based light emitting diodes (LEDs) have advantages over traditional LEDs because of their superior color purity, full spectrum coverage and low cost [4, 12].

Highly efficient quantum dot light-emitting diodes (QLEDs) require high quality QD emitters. Recently, QLEDs based on the core-shell type-I QDs such as CdSe/CdS, CdSe/ZnS have attracted much attention, due to their extremely high PL QYs and non-blinking behaviors [13–15]. In the type-I architecture the outer shell with a large band gap materials such as ZnS can act as a passivating layer to deal with redundant dangling bonds, and therefore benefits the suppressing of the non-radiational recombination pathways [16]. It also functions well as a physical barrier that prevents the electron-hole pairs from polarizing and keeping the emission wavelengths of the QLEDs unaffected from the applying electric fields by its screening effects to the external fields. However, the turn-on voltage of the QLEDs will inevitably increase due to the elevation of the barrier of the charge carriers passing through the large band gap shell and reaching to the emitting core. Besides, the band gap of the type-I QDs can hardly be tuned effectively to achieve a full color, because both the electrons and holes are confined in the core and the red-shift phenomenon is weakening with the increase of the particle size. A reverse type-I system where a small band gap shell is coated onto a large band gap core may provide a new material of choice to overcome these obstacles. In a reverse type-I QDs, both electrons and holes are confined in the shell and emission comes from the radiative recombinations of these electron-hole pairs in the shell. Thereby, one can expect a smaller injection barrier of type-I QD based LEDs as compared with that of type-I QD, because the charge carriers have to pass through the physical barrier from the large band gap shell before they get ready to emit photons in the core. A recent study have shown that the CdS/CdSe core/shell favors the extraction of photogenerated electrons and enhances the electron injection rate in QD-sensitized solar cells [17]. Moreover, Maity et al. have demonstrated that the electron (hole) transfer rate between reverse type-I CdS/CdSe and electron (hole) acceptor are much higher than that of type-I CdSe/CdS [18].

To this end, we intend to employ reverse type-I QDs as an emitting layer to construct a QLED to reduce the charge carrier injection barrier from anode/cathode, thus maximizing the electrically driven QD emission. Currently, the reverse type-I QD investigations are mainly limited to binary core-shell systems, such as CdS/HgS, CdS/CdSe, ZnSe/CdSe, ZnS/CdS and etc [19–23]. The QYs of these QDs are quite low, the highest of which is below 50%, which restricts their further applications to electroluminescent devices [24]. In fact, in a core-shell system, the defect states may be formed when a shell is coated onto a core, possibly owing to the lattice strain, dangling bonds or others. These defect states provide numerous channels for non-radiative relaxations that quench the fluorescence. Recent studies on type-I systems suggest that an alloy hetero-structured interface between the core and the shell may prevent defect formation, because the lattice strain is relaxed in the continuous composition gradient. The ternary alloy CdxZn1-xS with a band gap of about 3.0 eV, is a promising candidate for the wide band gap core material, owing to its sharp, distinctive feature in the absorption onset and high emission efficiency. The CdSe material proved a versatile shell to construct an efficient reverse type-I QDs. Besides, theoretical and experimental results reveal that combing these two materials will produce a reverse type-I QDs, because the conduction band (CB) of CdxZn1-xS core and CdSe shell are about −3.60 eV and −3.88 eV, while their valence band (VB) are −6.60 eV and −5.70 eV, respectively [25, 26].

In this work, we present the synthesis of CdxZn1-xS/CdSe to construct a reverse type-I system for the first time. The defect states formed by lattice mismatch are expected to be suppressed in continuous composition gradient growth at the interface between CdxZn1-xS and CdSe, thus leading to notable QYs ranging from 25% to 61% depending on the emission wavelengths. The QLEDs are fabricated by using the CdxZn1-xS/CdSe and CdSe/CdxZn1-xS QDs. Although a lower QY of reverse type-I CdxZn1-xS/CdSe, the luminance and the external quantum efficiency (EQE) much are higher than its type-I CdSe/CdxZn1-xS counterpart. Evidence show that the reverse type-I structure facilitates the injection of both the electrons and holes.

2. Experimental

2.1 Preparation of CdxZn1-xS/CdSe QDs

CdxZn1-xS core nanocrystals were synthesized according to previous reported method [27] but with some modifications. Briefly, 0.917 g of Zn acetate and 0.064 g CdO (the molar ratio of Zn and Cd is 10:1) were dissolved in a mixture solvent containing 4.0 ml of oleic acid (OA) and 10.0 ml of octadecene (ODE) in 50 ml of 3-neck reactor in 80 °C under the vacuum pump for 40 minutes. Then, the temperature of the reaction was persistent heated to 300 °C under N2 flow. At this temperature, 1.0 mmol sulphur was dissolved in 2.0 ml of ODE, and then the solution was injected into the reaction system rapidly. Subsequently, the temperature of the reaction system was raised to 310 °C and kept for 12 minutes. Finally, CdxZn1-xS cores were formed.

It is necessary to purity the CdxZn1-xS cores and dry as powder before use. The purpose is to remove the excess Zn element drastically and other impurity. Here, proper n-hexane was added into the CdxZn1-xS solution, followed by centrifugation and abandoning the white precipitate. Then, the supernatant containing QDs was added with excessive ethanol and centrifuged at 8000 r.p.m for 5 min. The above procedures should be repeated more than three times in order to obtain pure QDs. Finally, a slight yellow CdxZn1-xS solid was obtained and dried to a powder.

The purified CdxZn1-xS QD powder was mixed with 7.0 ml ODE and 3.0 ml of oleylamine (OAm) in a 50 ml 3-neck reactor (denoted as the main reaction). The reaction temperature was raised to 80 °C under the vacuum pump for 50 minutes, and then heated to 220 °C under N2 flow. When the main reaction reached the condition, a Se stock solution (0.15 mmol Se, prepared by dissolving selenium in 0.5ml Trioctylphosphine (TOP)) and 1.5 ml of ODE was added into the reaction. After 20 minutes, an equimolar amount of Cd precursor stock solution (prepared by dissolving CdO in OA and ODE (volume ratio, 1:1) at 200 °C under N2 flow) was added dropwisely (about 1 drop in every 2-3 s) to the main reaction. When the color of the solution showed no further changes, another cycle of Se/Cd precursor solution was added repeatedly until the CdxZn1-xS/CdSe had grown to a wanted size. Then, the adding of the Se/Cd precursors was stopped and the reaction was terminated by lowering the reaction to room temperature.

2.2 QLED fabrication

QLEDs were fabricated with pre-patterned indium tin oxide (ITO) coated glass substrates (sheet resistance, 15Ω/sq).The substrates were consecutively cleaned with deionized water, acetone, and isopropanol for 15 min and then treated with ultraviolet-ozone for 20 min. Subsequently, the pure substrates were transferred into an Ar-filled glove box for spin coating of layers. Firstly, poly-(ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) aqueous solution were spin coated onto the substrate at 3500 r.p.m for 50 s and annealed at 150 °C for 15 min. Then, poly(N,N'-bis(4-butylphenyl)-N, N'-bis(phenyl)benzidine) (poly-TPD) dispersed in chlorobenzene were spin coated at 2000 r.p.m for 30 s, followed by baking at 120 °C for 20 min. The Cd0.1Zn0.9S/CdSe QDs with emission wavelength at 625 nm and with PL QY>60% were dissolved in n-octane with a concentration of 20 mg/mL. QD layer was spin coated at 2000 r.p.m for 60 s and dried at room temperature. Zn0.95Mg0.05O nanoparticles dissolved in ethanol were spin-coated at 4000 r.p.m for 40 s, and annealed at 80 °C for 30 min. Finally, the multilayer samples were loaded into a vacuum evaporator with a base pressure of 4 × 10−4 Pa for deposition of an Ag cathode (100 nm).

2.3 Characterizations

The transmission electron microscopy (TEM) (JEM-2010 JEOL Ltd.), X-ray diffractometer (XRD) (Rigaku MiniFlex II X-ray diffractometer), photoluminescence (PL) spectrophotometer (Cary Eclipse, Varian) and UV-vis spectrophotometer (Cary 300, Varian) were employed to characterize the materials. Time resolved photoluminescence experiments were performed on a spectrometer (Bruker Optics 250IS/SM) with an intensified charge coupled device detector (CCD, Andor, IStar 740). The final concentration of each element was monitored by inductively coupled plasma atomic emission spectroscopy (ICP-AES, Leeman Co., USA, PROFILE SPEC). Absolute PL QYs of the prepared QDs were tested by an absolute QY test system (Quantaurus-QY C11347-11, Hamamatsu Photonics Co., Ltd.). The luminescent and the visual performance of the fabricated QLEDs were measured on a spectrometer (Maya 2000, Ocean Optics) with an integrating sphere (3P-GPS-033-SL, Labsphere).

3. Results and discussion

3.1 Structural characterizations

X-ray powder diffraction (XRD) patterns of CdxZn1-xS core and CdxZn1-xS/CdSe core/shell nanocrystals with increasing shell thickness are shown in Fig. 1. Through the analytic comparison, the CdxZn1-xS XRD pattern consists of the characteristic peaks 27.28°, 38.16°, 45.44°, 49.67° and 53.83°, which agrees well with the reported alloy QDs Zn0.9Cd0.1S peaks located at 26.83°, 39.40°, 47.27°, 51.50° and 56.06° (JCPDS 24-1136), corresponding to the planes (100) (102) (110) (103) and (112), respectively. Since the synthesis of the CdxZn1-xS/CdSe QDs is based on the same core and the thickness of the CdSe shell is different, we denote the QDs as Cd0.1Zn0.9S/CdSe (x mononlayer, x ML) for simplicity. The XRD patterns of Cd0.1Zn0.9S/CdSe (2 ML, curve b) show characteristic peaks located at 25.61°, 42.89° and 50.52°, which roughly corresponds to the standard zinc blende CdSe peaks positioned at 25.36°, 42.01° and 49.71° (JCPDS 88-2346), respectively. A superposition of peaks at about 25.36° is observed when the CdSe shell presents. The Cd0.1Zn0.9S XRD pattern consists of the characteristics peaks of wurtzite structure. However, after coated with the CdSe shell (2 ML), the XRD pattern of the Cd0.1Zn0.9S/CdSe shifts to the wurtzite CdSe-like pattern and further to a zinc blend CdSe-like pattern with the increase of the CdSe shell thickness (4 ML). Some related works have discussed the phase changes of the QDs with the increase of CdSe shell in detail [24, 28]. With a thicker CdSe shell (4 ML), the diffraction peaks of the QDs get closer to that of standard CdSe, with peaks located at 25.35°, 42.32° and 49.94°, corresponding to the crystal planes (111) (220) and (311), respectively. The lattice constant of CdSe is smaller than that of Cd0.1Zn0.9S/CdSe, and therefore a thicker CdSe shell leads to a peak shift to smaller angles and becomes a much CdSe-like phase. Similar phenomena are also observed in other related core-shell systems [28–30]. With the increase of the thickness of the CdSe (from 2 to 4 ML), the full width at half maximum (FWHM) decreases from 3.54° to 3.39° at the 25.61° peak. It is worth noting that the diffraction peaks get sharper with the increase of CdSe shell, indicating a well epitaxial growth of the CdSe shell onto the Cd0.1Zn0.9S core.

 

Fig. 1 XRD patterns of the pure Cd0.1Zn0.9S with a diameter of 4.5 nm, Cd0.1Zn0.9S/CdSe core/shell nanocrystals with CdSe shell thickness of 2 ML and 4 ML. The line XRD spectra correspond to bulk wurtzite Cd0.1Zn0.9S (bottom) and bulk zinc blende CdSe (top), respectively.

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The TEM images of the pure Cd0.1Zn0.9S cores and Cd0.1Zn0.9S/CdSe with 2 ML CdSe shell are shown in Fig. 2. All the TEM images show high crystallinity and nearly monodisperse of the QDs. According to the statistical results over 10 TEM images, the average diameter of Cd0.1Zn0.9S core is estimated about 4.5 nm. After introducing a CdSe shell, the diameter of the Cd0.1Zn0.9S/CdSe QDs is increased to about 6.5 nm, indicating that thickness of 1 ML CdSe is about 1.0 nm. This agrees well with the shell thickness of CdSe from the reported ZnSe/CdSe system [24]. From the lattice fringes of the high resolution TEM images, the interplaner distances are estimated to be 0.303 nm and 0.272 nm for Cd0.1Zn0.9S and Cd0.1Zn0.9S/CdSe (2 ML), respectively. The distance spacing d = 0.303 nm of the core is consistent with the (112) interplanar spacing 0.305 nm of the alloy Cd0.1Zn0.9S (JCPDS 24-1136). The distance spacing d = 0.272 nm of the Cd0.1Zn0.9S/CdSe is consistent with the interplaner distance 0.272 nm of the (311) plane of the zinc blende CdSe (JCPDS 88-2346). It again confirms that the CdSe is well overcoated onto the core. In order to determine the final concentration of each element, we tested transparent solution of the QDs core using inductively coupled plasma atomic emission spectroscopy. By linear fit of the ICP peak intensity of standard liquid, the relationship between the peak intensity and the concentration is obtained. After equivalent mathematical calculation, the composition of the pure CdxZn1-xS core is determined to be Cd0.1Zn0.9S. This agrees well with the XRD results. It is worth mentioning that the real Zn/Cd ratio (9:1) in CdxZn1-xS core is higher than the initial adding ratio (10:1). This phenomenon is originated from stronger bond ability of Cd-S than Zn-S. Note that the core/shell QDs are synthesized on the same core. Therefore, it is reasonable to express the composition of the as-prepared core/shell QDs as Cd0.1Zn0.9S/CdSe.

 

Fig. 2 (a) TEM image of Cd0.1Zn0.9S; (b) High resolution TEM image of Cd0.1Zn0.9S; (c) TEM image of Cd0.1Zn0.9S/CdSe with two monlayer (2 ML) CdSe shell; (d) High resolution TEM image of Cd0.1Zn0.9S/CdSe. Insets highlight the size distributions.

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3.2 Optical properties

Notable red shifts of the absorption and PL spectra are observed from Fig. 3, which gives direct evidence for the shell growth of CdSe. Figure 3(a) shows the digital photo of the as-prepared QDs in toluene. The resulting QDs exhibit bright full color emissions from blue to red, depending on the thickness of the CdSe shell. Detailed analysis of the PL and absorption spectra would give direct evidence for the shell growth of CdSe. The single PL emission peaks in the PL spectra together with nonobvious absorption features of CdSe in the absorption spectra demonstrates that there is no separate nucleation of CdSe nanocrystals. The Cd0.1Zn0.9S cores show a very sharp first excitonic absorption onset at 435 nm as shown in Fig. 3(b). After overcoated with CdSe shells, the excitonic aborption features are also distinctive, suggesting that a very narrow size distribution of the Cd0.1Zn0.9S/CdSe nanocrystals. Accordingly, the absorption onsets of the QDs are extended to wavelengths of λ = 556, 577, 587, 601, 620, and 635 nm for 1, 1.5, 2, 2.5, 3 and 4 ML CdSe, respectively. There are not any aborption tails in the lower energies, suggesting good optical properties of these QD suspensions without light scattering. Figure 3(c) shows the evolution of the PL spectra of the samples extracted from the reaction during the overcoating CdSe shell onto the same batch of Cd0.1Zn0.9S cores. With the CdSe shell growing on the Cd0.1Zn0.9S cores, the PL emission peaks significantly shift to the red range, which is consistent with the absorption band edges. In detail, the PL peaks of the as-prepared QDs are λ = 570, 591, 604, 616, 638, 650 nm, for 1, 1.5, 2, 2.5, 3 and 4 ML CdSe, respectively. Small Stokes shifts of about 15 nm between the emission peaks and the corresponding first excitonic absorption onsets are observed. This implies that the reverse type-I Cd0.1Zn0.9S/CdSe system prefers a band-edge luminescence rather than deep trap emission at the long-wavelength side, which is essential for high emission efficiency. The PL curve of the green QDs (1 ML, peak at 535 nm) shows a little unsymmetrical profile, indicating some trap states are formed due to the imperfectness outer shell. With a thicker shell, the PL curves become symmetric and the full width at half maximum (FWHM) decreased from 45 to 30 nm, indicating that the size focusing occurs with the shelling process. However, further growth of the CdSe leads to a FWHM increase and a QY decline (>3ML). The lower QYs and wider FWHM of the thicker shelled Cd0.1Zn0.9S/CdSe QDs may originate from the weaker quantum confinement effect, because the thickness of the shell may exceed the exciton Bohr radius of CdSe (5.4 nm). The optical parameters of the as-prepared reverse type-I Cd0.1Zn0.9S/CdSe are listed in Table 1. The red Cd0.1Zn0.9S/CdSe QDs (3 ML), shows a QY of 61%, a FWHM of 30 nm, which are comparable to those best reverse type-I reported elsewhere [24]. Since the red QDs exhibit best optical properties, we chose the red QDs for further LED investigations unless particularly claimed.

 

Fig. 3 (a) Digital photographs of Cd0.1Zn0.9S/CdSe QD solutions with different CdSe shell thickness under the irradiation of a UV lamp. The absorption (b) and PL (c) spectra of the QDs.

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Tables Icon

Table 1. Optical parameters of the QDs.

In order to study the effects of the shell thickness on the emission properties, time-resolved PL measurements were performed. After careful analysis of the decays, we found that a bi-exponential function was satisfactory in determining the kinetic parameters [31, 32]:

I(t)=[a1exp(-t/τ1)+a2exp(-t/τ2)]F(t)
where signal I(t) is the convolution of the impulse response function (IRF) and the bi-exponential function, a is the amplitude and τ denotes the lifetime. The average PL lifetime is given by

τ=a1τ12+a2τ22a1τ1+a2τ2

As shown in Fig. 4, the decays of QDs can be clearly decomposed into two parts: a fast decay within the first 10 ns followed by a long tail. Besides, Table 2 shows that the goodness-of-fit χ2 is below 1.3, indicating that our bi-exponential fitting is reliable. The long decay dominates the contribution to the whole decay curves, suggesting that the radiation mainly originates from the slow recombinations. Therefore, QDs with high emission efficiency requires enhancing the slow decay component and suppress the fast decay component. The amplitude and the long decay component τ2 are sensitive to the thickness of the CdSe shell, as listed in Table 2. The QD with 3 ML CdSe exhibits the highest amplitude 0.88, implying that the long decay component becomes more competitive and the non-radiative relaxation pathways are greatly suppressed. Besides the QD with 3ML CdSe exhibits a τ2 of 35 ns, which is the closest one to its average PL lifetime 34.4 ns. In other words, the PL decay curve is a more single-exponential like profile than its counterparts, which is essential for high PL QY.

 

Fig. 4 Time-resolved PL decays of the Cd0.1Zn0.9S/CdSe core/shell QDs with 1 ML, 2 ML, 3 ML and 4 ML CdSe shell in n-hexane, excited at λ = 573, 602, 632 and 653 nm, respectively.

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Tables Icon

Table 2. Kinetic parameters of the QDs obtained from time-resolved PL decays.

3.3 Electron and hole injection properties

The reverse type-I QDs are considered to have a small physical barrier to overcome, and therefore electrons and holes are easy to inject into the QDs from the hole transport layer (HTL). Because the electrons and holes contact directly to the outer shell CdSe, then they are not required to get into the core. They just reside in CdSe shell before undergoing radiative recombinations. On the contrary, electrons and holes intended to accumulate at the QDs/HTL interface with difficulty to inject into the electron transport layer (ETL) for CdSe/Cd0.1Zn0.9S QDs, due to the large physical barrier of Cd0.1Zn0.9S. In this architecture, both the electron and the hole wave functions are confined to the CdSe core, due to its type-I behaviors. As a result, electrons and holes should overcome the large barrier of the outer Cd0.1Zn0.9S to inject in the CdSe core where radiative recombination occurs. In order to reveal the charge carrier (electron and hole) transfer properties of the red Cd0.1Zn0.9S/CdSe reverse type-I QDs, we prepared CdSe/Cd0.1Zn0.9S type-I QDs with same emission wavelength for comparison. The optical properties and the synthesis method of this type-I QDs have been detailedly discussed in previous report [33]. Based on these two types of QDs, the electron-only devices with the structure of ITO/ZnMgO (80 nm)/QDs (20 nm)/ZnMgO/Al and hole-only device with the structure of ITO/PEDOT: PSS (~20 nm)/QDs (~20 nm)/Poly-TPD (~30nm)/Al were fabricated. The current densities of the electron-only devices based on both types of the QDs are much higher than that of hole-only devices, suggesting a higher mobility of electrons than that of holes (Fig. 5). This will cause the unbalanced transfer of electrons and holes and eventually causes an emission decline due to the unbalanced recombination and other undesired effects such as polaron-exciton quenching. However, the current density of the Cd0.1Zn0.9S/CdSe based hole-only device is almost 3 orders higher than that of the CdSe/Cd0.1Zn0.9S based one. Therefore, we conclude that reverse type-I Cd0.1Zn0.9S/CdSe QDs significantly reduce the hole injection barrier and facilitates the hole transport, thus leading to a better electron-hole balance as compared with its counterpart.

 

Fig. 5 The current density versus driving voltage of the electron-only (a) and the hole-only (b) devices.

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3.4 Device performances

The structure of the Cd0.1Zn0.9S/CdSe based LEDs is schematically shown in Fig. 6(a), and the corresponding to the cross-sectional TEM image of a typical device is shown in Fig. 6(b). In brief, the Cd0.1Zn0.9S/CdSe core/shell structure QDs-LEDs were fabricated by successive coating or evaporation a hole injection layer PEDOT: PSS, as a hole transport layer poly-TPD and a QD emitting layer, an electron transport layer ZnMgO and an Al electrode. The Al layer was deposited by thermal vacuum evaporation, and the other layers were sequentially spin-coated on a pre-patterned ITO transparent.

 

Fig. 6 (a) Schematic of the device structure; (b) Cross-sectional TEM image of a typical device.

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The electroluminescence (EL) and PL spectrum of a QLED device based on Cd0.1Zn0.9S/CdSe and CdSe/Cd0.1Zn0.9S QDs are shown in Fig. 7(a) and 7(b), where bright EL are observed with an emission peak located at 631 nm with high color purity (full width at half-maximum, FWHM 30nm), demonstrating that such QLED has inherited the PL color purity. The inset highlights the operated light-emitting device driven at the applied voltage of 5.0 V. Both of the devices show an EL peak of 631 nm, a 6-nm red shift to the solution PL spectrum (625 nm), owing to the inter-dot interaction enhancement from the close-packed film or dielectric dispersion of solvent [34]. It is worth mentioning that the FWHM line widths of the EL spectra are almost unchanged despite the driving voltages changing from 2.5 to 6.0 V. As shown in Fig. 7(c), a slight red shift of the peak is observed with the increase of driving voltages for the Cd0.1Zn0.9S/CdSe based device, which is ascribed to the so-called electric-field-induced Stark effect [35]. Whereas, the EL peak positions almost keep unchanged with the diriving voltages (Fig. 7(d)), probably due to the screening effect to the electric field from the wide band gap shell Cd0.1Zn0.9S. Figure 8(a) and 8(b) show the current density and luminance as a function of driving voltage of the Cd0.1Zn0.9S/CdSe and CdSe/Cd0.1Zn0.9S QLEDs. A lower turn-on voltage (VT = 1.8 V at 3.29 cd/m2) is achieved for Cd0.1Zn0.9S/CdSe than its CdSe/Cd0.1Zn0.9S counterpart (VT = 2.0 V at 1.96 cd/m2). Because the electrons and holes reside in the outer shell CdSe for Cd0.1Zn0.9S /CdSe QDs, due to its intrinsic reverse type-I behaviors, which facilitates the charge injection as compared to the type-I QDs. The luminance of Cd0.1Zn0.9S/CdSe is also higher than its counterpart, which is consistent with the variation of current density. At the driving voltage of 4.6 V, EQE of the Cd0.1Zn0.9S/CdSe based device shows a maximum value of 8.23% (Fig. 8(c)), which is 14.2% higher than its counterpart (5.8%), owing to its facile charge carrier injection. Although the type-I CdSe/Cd0.1Zn0.9S QDs have a higher PL QY than that of reverse type-I Cd0.1Zn0.9S/CdSe QDs, the device performances are much lower than reverse type-I Cd0.1Zn0.9S/CdSe QDs. This implies that charge injection barrier plays an important role in determining the final emission efficiency of the QLEDs. The reverse type-I Cd0.1Zn0.9S/CdSe based QLED reported here shows a luminance of 11412 cd/m2 at the EQE maximum of 8.23%, which are moderate in alloy QD based LED devices so far [36–39].

 

Fig. 7 PL and EL spectra of the Cd0.1Zn0.9S/CdSe (a) and CdSe/Cd0.1Zn0.9S (b) based LED; Evolution of EL spectra with driving voltages of the Cd0.1Zn0.9S/CdSe (c) and CdSe/Cd0.1Zn0.9S (d) based devices.

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Fig. 8 Current density, luminance of the Cd0.1Zn0.9S/CdSe (a), CdSe/Cd0.1Zn0.9S (b) based devices; (c) EQEs of the two devices.

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4. Conclusion

In summary, we have synthesized reverse type-I Cd0.1Zn0.9S/CdSe QDs with a high PL QY (625 nm, 61%) and a widely tunable emission, ranging from 450 to 670 nm. Two red QLEDs containing Cd0.1Zn0.9S/CdSe versus CdSe/Cd0.1Zn0.9S have been identically fabricated for comparison. Although the PL QY of Cd0.1Zn0.9S/CdSe is lower than CdSe/Cd0.1Zn0.9S QDs, the luminance and EQE of the Cd0.1Zn0.9S/CdSe QLED is much higher than its counterpart. In detail, Cd0.1Zn0.9S/CdSe QLED exhibits an EQE maximum of 8.23%, which is nearly 1.4 times higher as compared to its CdSe/Cd0.1Zn0.9S counterpart (5.8%). Electron- or hole- only experiments reveal that the Cd0.1Zn0.9S/CdSe with a reverse type-I structure facilitates the charge carrier injection. There is no need to overcome the physical barrier from the outer shell material as compare to the type-I CdSe/Cd0.1Zn0.9S QDs, because the electrons and holes reside in the CdSe shell for the reverse type-I Cd0.1Zn0.9S/CdSe QDs, which benefits the direct injection of the charge carriers. We hope that with further construction of the heterostructure system, the PL QYs and the charge injection ability of reverse type-I QDs will be enhanced further, making them comparable to the well-established type-I QLEDs.

Funding

Natural Science Foundation of China (11564026, 11774141 and 61765011), State Scholarship Fund (201608360030), Natural Science Foundation of Jiangxi Province (20151BAB212001, 20151BBE50114, 20171BAB202036 and 20161BAB212035), Outstanding Youth Funds of Jiangxi Province (20171BCB23051 and 20171BCB23052), Science and Technology Project of the Education Department of Jiangxi Province, China (GJJ150727 and GJJ160681).

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5. K.-S. Cho, E. K. Lee, W.-J. Joo, E. Jang, T.-H. Kim, S. J. Lee, S.-J. Kwon, J. Y. Han, B.-K. Kim, B. L. Choi, and J. M. Kim, “High-performance crosslinked colloidal quantum-dot light-emitting diodes,” Nat. Photonics 3, 341–345 (2009).

6. J. Bao and M. G. Bawendi, “A colloidal quantum dot spectrometer,” Nature 523(7558), 67–70 (2015). [PubMed]  

7. Q. H. Li, X. Jin, Y. Yang, H. N. Wang, H. J. Xu, Y. Y. Cheng, T. H. Wei, Y. C. Qin, X. B. Luo, W. F. Sun, and S. L. Luo, “Nd2(S, Se, Te)3 colloidal quantum dots: synthesis, energy level alignment, charge transfer dynamics, and their applications to solar cells,” Adv. Funct. Mater. 26, 254–266 (2016).

8. X. Jin, W. Sun, S. Luo, L. Shao, J. Zhang, X. Luo, T. Wei, Y. Qin, Y. Song, and Q. Li, “Energy gradient architectured praseodymium chalcogenide quantum dot solar cells: towards unidirectionally funneling energy transfer,” J. Mater. Chem. A Mater. Energy Sustain. 3, 23876–23887 (2015).

9. C. Burda, X. Chen, R. Narayanan, and M. A. El-Sayed, “Chemistry and properties of nanocrystals of different shapes,” Chem. Rev. 105(4), 1025–1102 (2005). [PubMed]  

10. B. G. Jeong, Y.-S. Park, J. H. Chang, I. Cho, J. K. Kim, H. Kim, K. Char, J. Cho, V. I. Klimov, P. Park, D. C. Lee, and W. K. Bae, “Colloidal spherical quantum wells with near-unity photoluminescence quantum yield and suppressed blinking,” ACS Nano 10, 9297–9305 (2016). [PubMed]  

11. J. J. Li, Y. A. Wang, W. Guo, J. C. Keay, T. D. Mishima, M. B. Johnson, and X. Peng, “Large-scale synthesis of nearly monodisperse CdSe/CdS core/shell nanocrystals using air-stable reagents via successive ion layer adsorption and reaction,” J. Am. Chem. Soc. 125(41), 12567–12575 (2003). [PubMed]  

12. Y. Shirasaki, G. J. Supran, M. G. Bawendi, and V. Bulovic, “Emergence of colloidal quantum-dot light-emitting technologies,” Nat. Photonics 7, 13–23 (2013).

13. B. Mahler, P. Spinicelli, S. Buil, X. Quelin, J.-P. Hermier, and B. Dubertret, “Towards non-blinking colloidal quantum dots,” Nat. Mater. 7(8), 659–664 (2008). [PubMed]  

14. O. Chen, J. Zhao, V. P. Chauhan, J. Cui, C. Wong, D. K. Harris, H. Wei, H.-S. Han, D. Fukumura, R. K. Jain, and M. G. Bawendi, “Compact high-quality CdSe-CdS core-shell nanocrystals with narrow emission linewidths and suppressed blinking,” Nat. Mater. 12(5), 445–451 (2013). [PubMed]  

15. D. Canneson, L. Biadala, S. Buil, X. Quélin, C. Javaux, B. Dubertret, and J. P. Hermier, “Blinking suppression and biexcitonic emission in thick-shell CdSe/CdS nanocrystals at cryogenic temperature,” Phys. Rev. B 89, 035303 (2014).

16. C. M. Tyrakowski, A. Shamirian, C. E. Rowland, H. Shen, A. Das, R. D. Schaller, and P. T. Snee, “Bright type II quantum dots,” Chem. Mater. 27, 7276–7281 (2015).

17. Z. Pan, H. Zhang, K. Cheng, Y. Hou, J. Hua, and X. Zhong, “Highly efficient inverted type-I CdS/CdSe core/shell structure QD-sensitized solar cells,” ACS Nano 6(5), 3982–3991 (2012). [PubMed]  

18. P. Maity, T. Debnath, and H. N. Ghosh, “Ultrafast charge carrier delocalization in CdSe/CdS quasi-type II and CdS/CdSe inverted type I core–shell: a structural analysis through carrier-quenching study,” J. Phys. Chem. C 119, 26202–26211 (2015).

19. F. Du, H. Zhang, X. Du, J. Zhu, and X. Zhong, “Controllable synthesis and optical properties of CdS/CdSe hetero-nanostructures with various dimensionalities,” Mater. Chem. Phys. 121, 118–124 (2010).

20. E. Groeneveld, L. Witteman, M. Lefferts, X. Ke, S. Bals, G. Van Tendeloo, and Cde. M. Donega, “Tailoring ZnSe-CdSe colloidal quantum dots via cation exchange: from core/shell to alloy nanocrystals,” ACS Nano 7(9), 7913–7930 (2013). [PubMed]  

21. H. Kumar, P. B. Barman, and R. R. Singh, “Low-Temperature growth of inverted hexagonal ZnS/CdS quantum dots: functional and luminescence properties,” J. Electron. Mater. 44, 675–681 (2014).

22. P. Maity, T. Debnath, T. Banerjee, A. Das, and H. N. Ghosh, “Charge delocalization in the cascade band structure CdS/CdSe and CdS/CdTe core–shell sensitized with Re(I)–polypyridyl complex,” J. Phys. Chem. C 120, 10051–10061 (2016).

23. W. Sukkabot, “Atomistic tight-binding computations of excitonic fine structure splitting in CdSe/ZnSe type-I and ZnSe/CdSe invert type-I core/shell nanocrystals,” Mater. Sci. Semicond. Process. 47, 57–61 (2016).

24. X. Zhong, R. Xie, Y. Zhang, T. Basché, and W. Knoll, “High-quality violet- to red-emitting ZnSe/CdSe core/shell nanocrystals,” Chem. Mater. 17, 4038–4042 (2005).

25. Q. Li, H. Meng, P. Zhou, Y. Zheng, J. Wang, J. Yu, and J. Gong, “Zn1–xCdxS solid solutions with controlled bandgap and enhanced visible-light photocatalytic H2-production activity,” ACS Catal. 3, 882–889 (2013).

26. K. V. Vokhmintcev, P. S. Samokhvalov, and I. Nabiev, “Charge transfer and separation in photoexcited quantum dot-based systems,” Nano Today 11, 189–211 (2016).

27. K.-H. Lee, J.-H. Lee, W.-S. Song, H. Ko, C. Lee, J.-H. Lee, and H. Yang, “Highly efficient, color-pure, color-stable blue quantum dot light-emitting devices,” ACS Nano 7(8), 7295–7302 (2013). [PubMed]  

28. Y. Niu, C. Pu, R. Lai, R. Meng, W. Lin, H. Qin, and X. Peng, “One-pot/three-step synthesis of zinc-blende CdSe/CdS core/shell nanocrystals with thick shells,” Nano Res. 10, 1149–1162 (2017).

29. H. Qin, Y. Niu, R. Meng, X. Lin, R. Lai, W. Fang, and X. Peng, “Single-dot spectroscopy of zinc-blende CdSe/CdS core/shell nanocrystals: nonblinking and correlation with ensemble measurements,” J. Am. Chem. Soc. 136(1), 179–187 (2014). [PubMed]  

30. W. Nan, Y. Niu, H. Qin, F. Cui, Y. Yang, R. Lai, W. Lin, and X. Peng, “Crystal structure control of zinc-blende CdSe/CdS core/shell nanocrystals: synthesis and structure-dependent optical properties,” J. Am. Chem. Soc. 134(48), 19685–19693 (2012). [PubMed]  

31. Q. Li, X. Jin, X. Yang, C. Chen, Z. Chen, Y. Qin, T.-h. Wei, and W. Sun, “Reducing the excess energy offset in organic/inorganic hybrid solar cells: Toward faster electron transfer,” Appl. Catal. B 162, 524–531 (2015).

32. X. Jin, W. Sun, Z. Chen, T. Wei, C. Chen, X. He, Y. Yuan, Y. Li, and Q. Li, “Exciton generation/dissociation/charge-transfer enhancement in inorganic/organic hybrid solar cells by robust single nanocrystalline LnPxOy (Ln = Eu, Y) doping,” ACS Appl. Mater. Interfaces 6(11), 8771–8781 (2014). [PubMed]  

33. P. Yang, M. Ando, and N. Murase, “Highly luminescent CdSe/CdxZn1-xS quantum dots coated with thickness-controlled SiO2 shell through silanization,” Langmuir 27(15), 9535–9540 (2011). [PubMed]  

34. J. Kwak, W. K. Bae, D. Lee, I. Park, J. Lim, M. Park, H. Cho, H. Woo, D. Y. Yoon, K. Char, S. Lee, and C. Lee, “Bright and efficient full-color colloidal quantum dot light-emitting diodes using an inverted device structure,” Nano Lett. 12(5), 2362–2366 (2012). [PubMed]  

35. V. Wood, M. J. Panzer, J. M. Caruge, J. E. Halpert, M. G. Bawendi, and V. Bulović, “Air-stable operation of transparent, colloidal quantum dot based LEDs with a unipolar device architecture,” Nano Lett. 10(1), 24–29 (2010). [PubMed]  

36. J. Kwak, J. Lim, M. Park, S. Lee, K. Char, and C. Lee, “High-power genuine ultraviolet light-emitting diodes based on colloidal nanocrystal quantum dots,” Nano Lett. 15(6), 3793–3799 (2015). [PubMed]  

37. W. K. Bae, M. K. Nam, K. Char, and S. Lee, “Gram-scale one-pot synthesis of highly luminescent blue emitting Cd1−xZnxS/ZnS nanocrystals,” Chem. Mater. 20, 5307–5313 (2008).

38. H. Shen, X. Bai, A. Wang, H. Wang, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “High-efficient deep-blue light-emitting diodes by using high quality ZnxCd1-xS/ZnS core/shell quantum dots,” Adv. Funct. Mater. 24, 2367–2373 (2014).

39. H. Shen, S. Wang, H. Wang, J. Niu, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “Highly efficient blue-green quantum dot light-emitting diodes using stable low-cadmium quaternary-alloy ZnCdSSe/ZnS core/shell nanocrystals,” ACS Appl. Mater. Interfaces 5(10), 4260–4265 (2013). [PubMed]  

References

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  4. X. Dai, Z. Zhang, Y. Jin, Y. Niu, H. Cao, X. Liang, L. Chen, J. Wang, and X. Peng, “Solution-processed, high-performance light-emitting diodes based on quantum dots,” Nature 515(7525), 96–99 (2014).
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  5. K.-S. Cho, E. K. Lee, W.-J. Joo, E. Jang, T.-H. Kim, S. J. Lee, S.-J. Kwon, J. Y. Han, B.-K. Kim, B. L. Choi, and J. M. Kim, “High-performance crosslinked colloidal quantum-dot light-emitting diodes,” Nat. Photonics 3, 341–345 (2009).
  6. J. Bao and M. G. Bawendi, “A colloidal quantum dot spectrometer,” Nature 523(7558), 67–70 (2015).
    [PubMed]
  7. Q. H. Li, X. Jin, Y. Yang, H. N. Wang, H. J. Xu, Y. Y. Cheng, T. H. Wei, Y. C. Qin, X. B. Luo, W. F. Sun, and S. L. Luo, “Nd2(S, Se, Te)3 colloidal quantum dots: synthesis, energy level alignment, charge transfer dynamics, and their applications to solar cells,” Adv. Funct. Mater. 26, 254–266 (2016).
  8. X. Jin, W. Sun, S. Luo, L. Shao, J. Zhang, X. Luo, T. Wei, Y. Qin, Y. Song, and Q. Li, “Energy gradient architectured praseodymium chalcogenide quantum dot solar cells: towards unidirectionally funneling energy transfer,” J. Mater. Chem. A Mater. Energy Sustain. 3, 23876–23887 (2015).
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  10. B. G. Jeong, Y.-S. Park, J. H. Chang, I. Cho, J. K. Kim, H. Kim, K. Char, J. Cho, V. I. Klimov, P. Park, D. C. Lee, and W. K. Bae, “Colloidal spherical quantum wells with near-unity photoluminescence quantum yield and suppressed blinking,” ACS Nano 10, 9297–9305 (2016).
    [PubMed]
  11. J. J. Li, Y. A. Wang, W. Guo, J. C. Keay, T. D. Mishima, M. B. Johnson, and X. Peng, “Large-scale synthesis of nearly monodisperse CdSe/CdS core/shell nanocrystals using air-stable reagents via successive ion layer adsorption and reaction,” J. Am. Chem. Soc. 125(41), 12567–12575 (2003).
    [PubMed]
  12. Y. Shirasaki, G. J. Supran, M. G. Bawendi, and V. Bulovic, “Emergence of colloidal quantum-dot light-emitting technologies,” Nat. Photonics 7, 13–23 (2013).
  13. B. Mahler, P. Spinicelli, S. Buil, X. Quelin, J.-P. Hermier, and B. Dubertret, “Towards non-blinking colloidal quantum dots,” Nat. Mater. 7(8), 659–664 (2008).
    [PubMed]
  14. O. Chen, J. Zhao, V. P. Chauhan, J. Cui, C. Wong, D. K. Harris, H. Wei, H.-S. Han, D. Fukumura, R. K. Jain, and M. G. Bawendi, “Compact high-quality CdSe-CdS core-shell nanocrystals with narrow emission linewidths and suppressed blinking,” Nat. Mater. 12(5), 445–451 (2013).
    [PubMed]
  15. D. Canneson, L. Biadala, S. Buil, X. Quélin, C. Javaux, B. Dubertret, and J. P. Hermier, “Blinking suppression and biexcitonic emission in thick-shell CdSe/CdS nanocrystals at cryogenic temperature,” Phys. Rev. B 89, 035303 (2014).
  16. C. M. Tyrakowski, A. Shamirian, C. E. Rowland, H. Shen, A. Das, R. D. Schaller, and P. T. Snee, “Bright type II quantum dots,” Chem. Mater. 27, 7276–7281 (2015).
  17. Z. Pan, H. Zhang, K. Cheng, Y. Hou, J. Hua, and X. Zhong, “Highly efficient inverted type-I CdS/CdSe core/shell structure QD-sensitized solar cells,” ACS Nano 6(5), 3982–3991 (2012).
    [PubMed]
  18. P. Maity, T. Debnath, and H. N. Ghosh, “Ultrafast charge carrier delocalization in CdSe/CdS quasi-type II and CdS/CdSe inverted type I core–shell: a structural analysis through carrier-quenching study,” J. Phys. Chem. C 119, 26202–26211 (2015).
  19. F. Du, H. Zhang, X. Du, J. Zhu, and X. Zhong, “Controllable synthesis and optical properties of CdS/CdSe hetero-nanostructures with various dimensionalities,” Mater. Chem. Phys. 121, 118–124 (2010).
  20. E. Groeneveld, L. Witteman, M. Lefferts, X. Ke, S. Bals, G. Van Tendeloo, and Cde. M. Donega, “Tailoring ZnSe-CdSe colloidal quantum dots via cation exchange: from core/shell to alloy nanocrystals,” ACS Nano 7(9), 7913–7930 (2013).
    [PubMed]
  21. H. Kumar, P. B. Barman, and R. R. Singh, “Low-Temperature growth of inverted hexagonal ZnS/CdS quantum dots: functional and luminescence properties,” J. Electron. Mater. 44, 675–681 (2014).
  22. P. Maity, T. Debnath, T. Banerjee, A. Das, and H. N. Ghosh, “Charge delocalization in the cascade band structure CdS/CdSe and CdS/CdTe core–shell sensitized with Re(I)–polypyridyl complex,” J. Phys. Chem. C 120, 10051–10061 (2016).
  23. W. Sukkabot, “Atomistic tight-binding computations of excitonic fine structure splitting in CdSe/ZnSe type-I and ZnSe/CdSe invert type-I core/shell nanocrystals,” Mater. Sci. Semicond. Process. 47, 57–61 (2016).
  24. X. Zhong, R. Xie, Y. Zhang, T. Basché, and W. Knoll, “High-quality violet- to red-emitting ZnSe/CdSe core/shell nanocrystals,” Chem. Mater. 17, 4038–4042 (2005).
  25. Q. Li, H. Meng, P. Zhou, Y. Zheng, J. Wang, J. Yu, and J. Gong, “Zn1–xCdxS solid solutions with controlled bandgap and enhanced visible-light photocatalytic H2-production activity,” ACS Catal. 3, 882–889 (2013).
  26. K. V. Vokhmintcev, P. S. Samokhvalov, and I. Nabiev, “Charge transfer and separation in photoexcited quantum dot-based systems,” Nano Today 11, 189–211 (2016).
  27. K.-H. Lee, J.-H. Lee, W.-S. Song, H. Ko, C. Lee, J.-H. Lee, and H. Yang, “Highly efficient, color-pure, color-stable blue quantum dot light-emitting devices,” ACS Nano 7(8), 7295–7302 (2013).
    [PubMed]
  28. Y. Niu, C. Pu, R. Lai, R. Meng, W. Lin, H. Qin, and X. Peng, “One-pot/three-step synthesis of zinc-blende CdSe/CdS core/shell nanocrystals with thick shells,” Nano Res. 10, 1149–1162 (2017).
  29. H. Qin, Y. Niu, R. Meng, X. Lin, R. Lai, W. Fang, and X. Peng, “Single-dot spectroscopy of zinc-blende CdSe/CdS core/shell nanocrystals: nonblinking and correlation with ensemble measurements,” J. Am. Chem. Soc. 136(1), 179–187 (2014).
    [PubMed]
  30. W. Nan, Y. Niu, H. Qin, F. Cui, Y. Yang, R. Lai, W. Lin, and X. Peng, “Crystal structure control of zinc-blende CdSe/CdS core/shell nanocrystals: synthesis and structure-dependent optical properties,” J. Am. Chem. Soc. 134(48), 19685–19693 (2012).
    [PubMed]
  31. Q. Li, X. Jin, X. Yang, C. Chen, Z. Chen, Y. Qin, T.-h. Wei, and W. Sun, “Reducing the excess energy offset in organic/inorganic hybrid solar cells: Toward faster electron transfer,” Appl. Catal. B 162, 524–531 (2015).
  32. X. Jin, W. Sun, Z. Chen, T. Wei, C. Chen, X. He, Y. Yuan, Y. Li, and Q. Li, “Exciton generation/dissociation/charge-transfer enhancement in inorganic/organic hybrid solar cells by robust single nanocrystalline LnPxOy (Ln = Eu, Y) doping,” ACS Appl. Mater. Interfaces 6(11), 8771–8781 (2014).
    [PubMed]
  33. P. Yang, M. Ando, and N. Murase, “Highly luminescent CdSe/CdxZn1-xS quantum dots coated with thickness-controlled SiO2 shell through silanization,” Langmuir 27(15), 9535–9540 (2011).
    [PubMed]
  34. J. Kwak, W. K. Bae, D. Lee, I. Park, J. Lim, M. Park, H. Cho, H. Woo, D. Y. Yoon, K. Char, S. Lee, and C. Lee, “Bright and efficient full-color colloidal quantum dot light-emitting diodes using an inverted device structure,” Nano Lett. 12(5), 2362–2366 (2012).
    [PubMed]
  35. V. Wood, M. J. Panzer, J. M. Caruge, J. E. Halpert, M. G. Bawendi, and V. Bulović, “Air-stable operation of transparent, colloidal quantum dot based LEDs with a unipolar device architecture,” Nano Lett. 10(1), 24–29 (2010).
    [PubMed]
  36. J. Kwak, J. Lim, M. Park, S. Lee, K. Char, and C. Lee, “High-power genuine ultraviolet light-emitting diodes based on colloidal nanocrystal quantum dots,” Nano Lett. 15(6), 3793–3799 (2015).
    [PubMed]
  37. W. K. Bae, M. K. Nam, K. Char, and S. Lee, “Gram-scale one-pot synthesis of highly luminescent blue emitting Cd1−xZnxS/ZnS nanocrystals,” Chem. Mater. 20, 5307–5313 (2008).
  38. H. Shen, X. Bai, A. Wang, H. Wang, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “High-efficient deep-blue light-emitting diodes by using high quality ZnxCd1-xS/ZnS core/shell quantum dots,” Adv. Funct. Mater. 24, 2367–2373 (2014).
  39. H. Shen, S. Wang, H. Wang, J. Niu, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “Highly efficient blue-green quantum dot light-emitting diodes using stable low-cadmium quaternary-alloy ZnCdSSe/ZnS core/shell nanocrystals,” ACS Appl. Mater. Interfaces 5(10), 4260–4265 (2013).
    [PubMed]

2017 (1)

Y. Niu, C. Pu, R. Lai, R. Meng, W. Lin, H. Qin, and X. Peng, “One-pot/three-step synthesis of zinc-blende CdSe/CdS core/shell nanocrystals with thick shells,” Nano Res. 10, 1149–1162 (2017).

2016 (5)

P. Maity, T. Debnath, T. Banerjee, A. Das, and H. N. Ghosh, “Charge delocalization in the cascade band structure CdS/CdSe and CdS/CdTe core–shell sensitized with Re(I)–polypyridyl complex,” J. Phys. Chem. C 120, 10051–10061 (2016).

W. Sukkabot, “Atomistic tight-binding computations of excitonic fine structure splitting in CdSe/ZnSe type-I and ZnSe/CdSe invert type-I core/shell nanocrystals,” Mater. Sci. Semicond. Process. 47, 57–61 (2016).

K. V. Vokhmintcev, P. S. Samokhvalov, and I. Nabiev, “Charge transfer and separation in photoexcited quantum dot-based systems,” Nano Today 11, 189–211 (2016).

Q. H. Li, X. Jin, Y. Yang, H. N. Wang, H. J. Xu, Y. Y. Cheng, T. H. Wei, Y. C. Qin, X. B. Luo, W. F. Sun, and S. L. Luo, “Nd2(S, Se, Te)3 colloidal quantum dots: synthesis, energy level alignment, charge transfer dynamics, and their applications to solar cells,” Adv. Funct. Mater. 26, 254–266 (2016).

B. G. Jeong, Y.-S. Park, J. H. Chang, I. Cho, J. K. Kim, H. Kim, K. Char, J. Cho, V. I. Klimov, P. Park, D. C. Lee, and W. K. Bae, “Colloidal spherical quantum wells with near-unity photoluminescence quantum yield and suppressed blinking,” ACS Nano 10, 9297–9305 (2016).
[PubMed]

2015 (7)

X. Jin, W. Sun, S. Luo, L. Shao, J. Zhang, X. Luo, T. Wei, Y. Qin, Y. Song, and Q. Li, “Energy gradient architectured praseodymium chalcogenide quantum dot solar cells: towards unidirectionally funneling energy transfer,” J. Mater. Chem. A Mater. Energy Sustain. 3, 23876–23887 (2015).

W. H. Evers, J. M. Schins, M. Aerts, A. Kulkarni, P. Capiod, M. Berthe, B. Grandidier, C. Delerue, H. S. J. van der Zant, C. van Overbeek, J. L. Peters, D. Vanmaekelbergh, and L. D. A. Siebbeles, “High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds,” Nat. Commun. 6, 8195 (2015).
[PubMed]

J. Bao and M. G. Bawendi, “A colloidal quantum dot spectrometer,” Nature 523(7558), 67–70 (2015).
[PubMed]

C. M. Tyrakowski, A. Shamirian, C. E. Rowland, H. Shen, A. Das, R. D. Schaller, and P. T. Snee, “Bright type II quantum dots,” Chem. Mater. 27, 7276–7281 (2015).

P. Maity, T. Debnath, and H. N. Ghosh, “Ultrafast charge carrier delocalization in CdSe/CdS quasi-type II and CdS/CdSe inverted type I core–shell: a structural analysis through carrier-quenching study,” J. Phys. Chem. C 119, 26202–26211 (2015).

Q. Li, X. Jin, X. Yang, C. Chen, Z. Chen, Y. Qin, T.-h. Wei, and W. Sun, “Reducing the excess energy offset in organic/inorganic hybrid solar cells: Toward faster electron transfer,” Appl. Catal. B 162, 524–531 (2015).

J. Kwak, J. Lim, M. Park, S. Lee, K. Char, and C. Lee, “High-power genuine ultraviolet light-emitting diodes based on colloidal nanocrystal quantum dots,” Nano Lett. 15(6), 3793–3799 (2015).
[PubMed]

2014 (6)

X. Jin, W. Sun, Z. Chen, T. Wei, C. Chen, X. He, Y. Yuan, Y. Li, and Q. Li, “Exciton generation/dissociation/charge-transfer enhancement in inorganic/organic hybrid solar cells by robust single nanocrystalline LnPxOy (Ln = Eu, Y) doping,” ACS Appl. Mater. Interfaces 6(11), 8771–8781 (2014).
[PubMed]

H. Qin, Y. Niu, R. Meng, X. Lin, R. Lai, W. Fang, and X. Peng, “Single-dot spectroscopy of zinc-blende CdSe/CdS core/shell nanocrystals: nonblinking and correlation with ensemble measurements,” J. Am. Chem. Soc. 136(1), 179–187 (2014).
[PubMed]

H. Kumar, P. B. Barman, and R. R. Singh, “Low-Temperature growth of inverted hexagonal ZnS/CdS quantum dots: functional and luminescence properties,” J. Electron. Mater. 44, 675–681 (2014).

D. Canneson, L. Biadala, S. Buil, X. Quélin, C. Javaux, B. Dubertret, and J. P. Hermier, “Blinking suppression and biexcitonic emission in thick-shell CdSe/CdS nanocrystals at cryogenic temperature,” Phys. Rev. B 89, 035303 (2014).

X. Dai, Z. Zhang, Y. Jin, Y. Niu, H. Cao, X. Liang, L. Chen, J. Wang, and X. Peng, “Solution-processed, high-performance light-emitting diodes based on quantum dots,” Nature 515(7525), 96–99 (2014).
[PubMed]

H. Shen, X. Bai, A. Wang, H. Wang, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “High-efficient deep-blue light-emitting diodes by using high quality ZnxCd1-xS/ZnS core/shell quantum dots,” Adv. Funct. Mater. 24, 2367–2373 (2014).

2013 (6)

H. Shen, S. Wang, H. Wang, J. Niu, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “Highly efficient blue-green quantum dot light-emitting diodes using stable low-cadmium quaternary-alloy ZnCdSSe/ZnS core/shell nanocrystals,” ACS Appl. Mater. Interfaces 5(10), 4260–4265 (2013).
[PubMed]

O. Chen, J. Zhao, V. P. Chauhan, J. Cui, C. Wong, D. K. Harris, H. Wei, H.-S. Han, D. Fukumura, R. K. Jain, and M. G. Bawendi, “Compact high-quality CdSe-CdS core-shell nanocrystals with narrow emission linewidths and suppressed blinking,” Nat. Mater. 12(5), 445–451 (2013).
[PubMed]

Y. Shirasaki, G. J. Supran, M. G. Bawendi, and V. Bulovic, “Emergence of colloidal quantum-dot light-emitting technologies,” Nat. Photonics 7, 13–23 (2013).

E. Groeneveld, L. Witteman, M. Lefferts, X. Ke, S. Bals, G. Van Tendeloo, and Cde. M. Donega, “Tailoring ZnSe-CdSe colloidal quantum dots via cation exchange: from core/shell to alloy nanocrystals,” ACS Nano 7(9), 7913–7930 (2013).
[PubMed]

Q. Li, H. Meng, P. Zhou, Y. Zheng, J. Wang, J. Yu, and J. Gong, “Zn1–xCdxS solid solutions with controlled bandgap and enhanced visible-light photocatalytic H2-production activity,” ACS Catal. 3, 882–889 (2013).

K.-H. Lee, J.-H. Lee, W.-S. Song, H. Ko, C. Lee, J.-H. Lee, and H. Yang, “Highly efficient, color-pure, color-stable blue quantum dot light-emitting devices,” ACS Nano 7(8), 7295–7302 (2013).
[PubMed]

2012 (3)

W. Nan, Y. Niu, H. Qin, F. Cui, Y. Yang, R. Lai, W. Lin, and X. Peng, “Crystal structure control of zinc-blende CdSe/CdS core/shell nanocrystals: synthesis and structure-dependent optical properties,” J. Am. Chem. Soc. 134(48), 19685–19693 (2012).
[PubMed]

J. Kwak, W. K. Bae, D. Lee, I. Park, J. Lim, M. Park, H. Cho, H. Woo, D. Y. Yoon, K. Char, S. Lee, and C. Lee, “Bright and efficient full-color colloidal quantum dot light-emitting diodes using an inverted device structure,” Nano Lett. 12(5), 2362–2366 (2012).
[PubMed]

Z. Pan, H. Zhang, K. Cheng, Y. Hou, J. Hua, and X. Zhong, “Highly efficient inverted type-I CdS/CdSe core/shell structure QD-sensitized solar cells,” ACS Nano 6(5), 3982–3991 (2012).
[PubMed]

2011 (1)

P. Yang, M. Ando, and N. Murase, “Highly luminescent CdSe/CdxZn1-xS quantum dots coated with thickness-controlled SiO2 shell through silanization,” Langmuir 27(15), 9535–9540 (2011).
[PubMed]

2010 (2)

V. Wood, M. J. Panzer, J. M. Caruge, J. E. Halpert, M. G. Bawendi, and V. Bulović, “Air-stable operation of transparent, colloidal quantum dot based LEDs with a unipolar device architecture,” Nano Lett. 10(1), 24–29 (2010).
[PubMed]

F. Du, H. Zhang, X. Du, J. Zhu, and X. Zhong, “Controllable synthesis and optical properties of CdS/CdSe hetero-nanostructures with various dimensionalities,” Mater. Chem. Phys. 121, 118–124 (2010).

2009 (1)

K.-S. Cho, E. K. Lee, W.-J. Joo, E. Jang, T.-H. Kim, S. J. Lee, S.-J. Kwon, J. Y. Han, B.-K. Kim, B. L. Choi, and J. M. Kim, “High-performance crosslinked colloidal quantum-dot light-emitting diodes,” Nat. Photonics 3, 341–345 (2009).

2008 (2)

B. Mahler, P. Spinicelli, S. Buil, X. Quelin, J.-P. Hermier, and B. Dubertret, “Towards non-blinking colloidal quantum dots,” Nat. Mater. 7(8), 659–664 (2008).
[PubMed]

W. K. Bae, M. K. Nam, K. Char, and S. Lee, “Gram-scale one-pot synthesis of highly luminescent blue emitting Cd1−xZnxS/ZnS nanocrystals,” Chem. Mater. 20, 5307–5313 (2008).

2005 (2)

X. Zhong, R. Xie, Y. Zhang, T. Basché, and W. Knoll, “High-quality violet- to red-emitting ZnSe/CdSe core/shell nanocrystals,” Chem. Mater. 17, 4038–4042 (2005).

C. Burda, X. Chen, R. Narayanan, and M. A. El-Sayed, “Chemistry and properties of nanocrystals of different shapes,” Chem. Rev. 105(4), 1025–1102 (2005).
[PubMed]

2003 (1)

J. J. Li, Y. A. Wang, W. Guo, J. C. Keay, T. D. Mishima, M. B. Johnson, and X. Peng, “Large-scale synthesis of nearly monodisperse CdSe/CdS core/shell nanocrystals using air-stable reagents via successive ion layer adsorption and reaction,” J. Am. Chem. Soc. 125(41), 12567–12575 (2003).
[PubMed]

2000 (1)

X. Peng, L. Manna, W. Yang, J. Wickham, E. Scher, A. Kadavanich, and A. P. Alivisatos, “Shape control of CdSe nanocrystals,” Nature 404(6773), 59–61 (2000).
[PubMed]

1996 (1)

A. P. Alivisatos, “Semiconductor clusters, nanocrystals, and quantum dots,” Science 271, 933–937 (1996).

Aerts, M.

W. H. Evers, J. M. Schins, M. Aerts, A. Kulkarni, P. Capiod, M. Berthe, B. Grandidier, C. Delerue, H. S. J. van der Zant, C. van Overbeek, J. L. Peters, D. Vanmaekelbergh, and L. D. A. Siebbeles, “High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds,” Nat. Commun. 6, 8195 (2015).
[PubMed]

Alivisatos, A. P.

X. Peng, L. Manna, W. Yang, J. Wickham, E. Scher, A. Kadavanich, and A. P. Alivisatos, “Shape control of CdSe nanocrystals,” Nature 404(6773), 59–61 (2000).
[PubMed]

A. P. Alivisatos, “Semiconductor clusters, nanocrystals, and quantum dots,” Science 271, 933–937 (1996).

Ando, M.

P. Yang, M. Ando, and N. Murase, “Highly luminescent CdSe/CdxZn1-xS quantum dots coated with thickness-controlled SiO2 shell through silanization,” Langmuir 27(15), 9535–9540 (2011).
[PubMed]

Bae, W. K.

B. G. Jeong, Y.-S. Park, J. H. Chang, I. Cho, J. K. Kim, H. Kim, K. Char, J. Cho, V. I. Klimov, P. Park, D. C. Lee, and W. K. Bae, “Colloidal spherical quantum wells with near-unity photoluminescence quantum yield and suppressed blinking,” ACS Nano 10, 9297–9305 (2016).
[PubMed]

J. Kwak, W. K. Bae, D. Lee, I. Park, J. Lim, M. Park, H. Cho, H. Woo, D. Y. Yoon, K. Char, S. Lee, and C. Lee, “Bright and efficient full-color colloidal quantum dot light-emitting diodes using an inverted device structure,” Nano Lett. 12(5), 2362–2366 (2012).
[PubMed]

W. K. Bae, M. K. Nam, K. Char, and S. Lee, “Gram-scale one-pot synthesis of highly luminescent blue emitting Cd1−xZnxS/ZnS nanocrystals,” Chem. Mater. 20, 5307–5313 (2008).

Bai, X.

H. Shen, X. Bai, A. Wang, H. Wang, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “High-efficient deep-blue light-emitting diodes by using high quality ZnxCd1-xS/ZnS core/shell quantum dots,” Adv. Funct. Mater. 24, 2367–2373 (2014).

Bals, S.

E. Groeneveld, L. Witteman, M. Lefferts, X. Ke, S. Bals, G. Van Tendeloo, and Cde. M. Donega, “Tailoring ZnSe-CdSe colloidal quantum dots via cation exchange: from core/shell to alloy nanocrystals,” ACS Nano 7(9), 7913–7930 (2013).
[PubMed]

Banerjee, T.

P. Maity, T. Debnath, T. Banerjee, A. Das, and H. N. Ghosh, “Charge delocalization in the cascade band structure CdS/CdSe and CdS/CdTe core–shell sensitized with Re(I)–polypyridyl complex,” J. Phys. Chem. C 120, 10051–10061 (2016).

Bao, J.

J. Bao and M. G. Bawendi, “A colloidal quantum dot spectrometer,” Nature 523(7558), 67–70 (2015).
[PubMed]

Barman, P. B.

H. Kumar, P. B. Barman, and R. R. Singh, “Low-Temperature growth of inverted hexagonal ZnS/CdS quantum dots: functional and luminescence properties,” J. Electron. Mater. 44, 675–681 (2014).

Basché, T.

X. Zhong, R. Xie, Y. Zhang, T. Basché, and W. Knoll, “High-quality violet- to red-emitting ZnSe/CdSe core/shell nanocrystals,” Chem. Mater. 17, 4038–4042 (2005).

Bawendi, M. G.

J. Bao and M. G. Bawendi, “A colloidal quantum dot spectrometer,” Nature 523(7558), 67–70 (2015).
[PubMed]

O. Chen, J. Zhao, V. P. Chauhan, J. Cui, C. Wong, D. K. Harris, H. Wei, H.-S. Han, D. Fukumura, R. K. Jain, and M. G. Bawendi, “Compact high-quality CdSe-CdS core-shell nanocrystals with narrow emission linewidths and suppressed blinking,” Nat. Mater. 12(5), 445–451 (2013).
[PubMed]

Y. Shirasaki, G. J. Supran, M. G. Bawendi, and V. Bulovic, “Emergence of colloidal quantum-dot light-emitting technologies,” Nat. Photonics 7, 13–23 (2013).

V. Wood, M. J. Panzer, J. M. Caruge, J. E. Halpert, M. G. Bawendi, and V. Bulović, “Air-stable operation of transparent, colloidal quantum dot based LEDs with a unipolar device architecture,” Nano Lett. 10(1), 24–29 (2010).
[PubMed]

Berthe, M.

W. H. Evers, J. M. Schins, M. Aerts, A. Kulkarni, P. Capiod, M. Berthe, B. Grandidier, C. Delerue, H. S. J. van der Zant, C. van Overbeek, J. L. Peters, D. Vanmaekelbergh, and L. D. A. Siebbeles, “High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds,” Nat. Commun. 6, 8195 (2015).
[PubMed]

Biadala, L.

D. Canneson, L. Biadala, S. Buil, X. Quélin, C. Javaux, B. Dubertret, and J. P. Hermier, “Blinking suppression and biexcitonic emission in thick-shell CdSe/CdS nanocrystals at cryogenic temperature,” Phys. Rev. B 89, 035303 (2014).

Buil, S.

D. Canneson, L. Biadala, S. Buil, X. Quélin, C. Javaux, B. Dubertret, and J. P. Hermier, “Blinking suppression and biexcitonic emission in thick-shell CdSe/CdS nanocrystals at cryogenic temperature,” Phys. Rev. B 89, 035303 (2014).

B. Mahler, P. Spinicelli, S. Buil, X. Quelin, J.-P. Hermier, and B. Dubertret, “Towards non-blinking colloidal quantum dots,” Nat. Mater. 7(8), 659–664 (2008).
[PubMed]

Bulovic, V.

Y. Shirasaki, G. J. Supran, M. G. Bawendi, and V. Bulovic, “Emergence of colloidal quantum-dot light-emitting technologies,” Nat. Photonics 7, 13–23 (2013).

V. Wood, M. J. Panzer, J. M. Caruge, J. E. Halpert, M. G. Bawendi, and V. Bulović, “Air-stable operation of transparent, colloidal quantum dot based LEDs with a unipolar device architecture,” Nano Lett. 10(1), 24–29 (2010).
[PubMed]

Burda, C.

C. Burda, X. Chen, R. Narayanan, and M. A. El-Sayed, “Chemistry and properties of nanocrystals of different shapes,” Chem. Rev. 105(4), 1025–1102 (2005).
[PubMed]

Canneson, D.

D. Canneson, L. Biadala, S. Buil, X. Quélin, C. Javaux, B. Dubertret, and J. P. Hermier, “Blinking suppression and biexcitonic emission in thick-shell CdSe/CdS nanocrystals at cryogenic temperature,” Phys. Rev. B 89, 035303 (2014).

Cao, H.

X. Dai, Z. Zhang, Y. Jin, Y. Niu, H. Cao, X. Liang, L. Chen, J. Wang, and X. Peng, “Solution-processed, high-performance light-emitting diodes based on quantum dots,” Nature 515(7525), 96–99 (2014).
[PubMed]

Capiod, P.

W. H. Evers, J. M. Schins, M. Aerts, A. Kulkarni, P. Capiod, M. Berthe, B. Grandidier, C. Delerue, H. S. J. van der Zant, C. van Overbeek, J. L. Peters, D. Vanmaekelbergh, and L. D. A. Siebbeles, “High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds,” Nat. Commun. 6, 8195 (2015).
[PubMed]

Caruge, J. M.

V. Wood, M. J. Panzer, J. M. Caruge, J. E. Halpert, M. G. Bawendi, and V. Bulović, “Air-stable operation of transparent, colloidal quantum dot based LEDs with a unipolar device architecture,” Nano Lett. 10(1), 24–29 (2010).
[PubMed]

Chang, J. H.

B. G. Jeong, Y.-S. Park, J. H. Chang, I. Cho, J. K. Kim, H. Kim, K. Char, J. Cho, V. I. Klimov, P. Park, D. C. Lee, and W. K. Bae, “Colloidal spherical quantum wells with near-unity photoluminescence quantum yield and suppressed blinking,” ACS Nano 10, 9297–9305 (2016).
[PubMed]

Char, K.

B. G. Jeong, Y.-S. Park, J. H. Chang, I. Cho, J. K. Kim, H. Kim, K. Char, J. Cho, V. I. Klimov, P. Park, D. C. Lee, and W. K. Bae, “Colloidal spherical quantum wells with near-unity photoluminescence quantum yield and suppressed blinking,” ACS Nano 10, 9297–9305 (2016).
[PubMed]

J. Kwak, J. Lim, M. Park, S. Lee, K. Char, and C. Lee, “High-power genuine ultraviolet light-emitting diodes based on colloidal nanocrystal quantum dots,” Nano Lett. 15(6), 3793–3799 (2015).
[PubMed]

J. Kwak, W. K. Bae, D. Lee, I. Park, J. Lim, M. Park, H. Cho, H. Woo, D. Y. Yoon, K. Char, S. Lee, and C. Lee, “Bright and efficient full-color colloidal quantum dot light-emitting diodes using an inverted device structure,” Nano Lett. 12(5), 2362–2366 (2012).
[PubMed]

W. K. Bae, M. K. Nam, K. Char, and S. Lee, “Gram-scale one-pot synthesis of highly luminescent blue emitting Cd1−xZnxS/ZnS nanocrystals,” Chem. Mater. 20, 5307–5313 (2008).

Chauhan, V. P.

O. Chen, J. Zhao, V. P. Chauhan, J. Cui, C. Wong, D. K. Harris, H. Wei, H.-S. Han, D. Fukumura, R. K. Jain, and M. G. Bawendi, “Compact high-quality CdSe-CdS core-shell nanocrystals with narrow emission linewidths and suppressed blinking,” Nat. Mater. 12(5), 445–451 (2013).
[PubMed]

Chen, C.

Q. Li, X. Jin, X. Yang, C. Chen, Z. Chen, Y. Qin, T.-h. Wei, and W. Sun, “Reducing the excess energy offset in organic/inorganic hybrid solar cells: Toward faster electron transfer,” Appl. Catal. B 162, 524–531 (2015).

X. Jin, W. Sun, Z. Chen, T. Wei, C. Chen, X. He, Y. Yuan, Y. Li, and Q. Li, “Exciton generation/dissociation/charge-transfer enhancement in inorganic/organic hybrid solar cells by robust single nanocrystalline LnPxOy (Ln = Eu, Y) doping,” ACS Appl. Mater. Interfaces 6(11), 8771–8781 (2014).
[PubMed]

Chen, L.

X. Dai, Z. Zhang, Y. Jin, Y. Niu, H. Cao, X. Liang, L. Chen, J. Wang, and X. Peng, “Solution-processed, high-performance light-emitting diodes based on quantum dots,” Nature 515(7525), 96–99 (2014).
[PubMed]

Chen, O.

O. Chen, J. Zhao, V. P. Chauhan, J. Cui, C. Wong, D. K. Harris, H. Wei, H.-S. Han, D. Fukumura, R. K. Jain, and M. G. Bawendi, “Compact high-quality CdSe-CdS core-shell nanocrystals with narrow emission linewidths and suppressed blinking,” Nat. Mater. 12(5), 445–451 (2013).
[PubMed]

Chen, X.

C. Burda, X. Chen, R. Narayanan, and M. A. El-Sayed, “Chemistry and properties of nanocrystals of different shapes,” Chem. Rev. 105(4), 1025–1102 (2005).
[PubMed]

Chen, Z.

Q. Li, X. Jin, X. Yang, C. Chen, Z. Chen, Y. Qin, T.-h. Wei, and W. Sun, “Reducing the excess energy offset in organic/inorganic hybrid solar cells: Toward faster electron transfer,” Appl. Catal. B 162, 524–531 (2015).

X. Jin, W. Sun, Z. Chen, T. Wei, C. Chen, X. He, Y. Yuan, Y. Li, and Q. Li, “Exciton generation/dissociation/charge-transfer enhancement in inorganic/organic hybrid solar cells by robust single nanocrystalline LnPxOy (Ln = Eu, Y) doping,” ACS Appl. Mater. Interfaces 6(11), 8771–8781 (2014).
[PubMed]

Cheng, K.

Z. Pan, H. Zhang, K. Cheng, Y. Hou, J. Hua, and X. Zhong, “Highly efficient inverted type-I CdS/CdSe core/shell structure QD-sensitized solar cells,” ACS Nano 6(5), 3982–3991 (2012).
[PubMed]

Cheng, Y. Y.

Q. H. Li, X. Jin, Y. Yang, H. N. Wang, H. J. Xu, Y. Y. Cheng, T. H. Wei, Y. C. Qin, X. B. Luo, W. F. Sun, and S. L. Luo, “Nd2(S, Se, Te)3 colloidal quantum dots: synthesis, energy level alignment, charge transfer dynamics, and their applications to solar cells,” Adv. Funct. Mater. 26, 254–266 (2016).

Cho, H.

J. Kwak, W. K. Bae, D. Lee, I. Park, J. Lim, M. Park, H. Cho, H. Woo, D. Y. Yoon, K. Char, S. Lee, and C. Lee, “Bright and efficient full-color colloidal quantum dot light-emitting diodes using an inverted device structure,” Nano Lett. 12(5), 2362–2366 (2012).
[PubMed]

Cho, I.

B. G. Jeong, Y.-S. Park, J. H. Chang, I. Cho, J. K. Kim, H. Kim, K. Char, J. Cho, V. I. Klimov, P. Park, D. C. Lee, and W. K. Bae, “Colloidal spherical quantum wells with near-unity photoluminescence quantum yield and suppressed blinking,” ACS Nano 10, 9297–9305 (2016).
[PubMed]

Cho, J.

B. G. Jeong, Y.-S. Park, J. H. Chang, I. Cho, J. K. Kim, H. Kim, K. Char, J. Cho, V. I. Klimov, P. Park, D. C. Lee, and W. K. Bae, “Colloidal spherical quantum wells with near-unity photoluminescence quantum yield and suppressed blinking,” ACS Nano 10, 9297–9305 (2016).
[PubMed]

Cho, K.-S.

K.-S. Cho, E. K. Lee, W.-J. Joo, E. Jang, T.-H. Kim, S. J. Lee, S.-J. Kwon, J. Y. Han, B.-K. Kim, B. L. Choi, and J. M. Kim, “High-performance crosslinked colloidal quantum-dot light-emitting diodes,” Nat. Photonics 3, 341–345 (2009).

Choi, B. L.

K.-S. Cho, E. K. Lee, W.-J. Joo, E. Jang, T.-H. Kim, S. J. Lee, S.-J. Kwon, J. Y. Han, B.-K. Kim, B. L. Choi, and J. M. Kim, “High-performance crosslinked colloidal quantum-dot light-emitting diodes,” Nat. Photonics 3, 341–345 (2009).

Cui, F.

W. Nan, Y. Niu, H. Qin, F. Cui, Y. Yang, R. Lai, W. Lin, and X. Peng, “Crystal structure control of zinc-blende CdSe/CdS core/shell nanocrystals: synthesis and structure-dependent optical properties,” J. Am. Chem. Soc. 134(48), 19685–19693 (2012).
[PubMed]

Cui, J.

O. Chen, J. Zhao, V. P. Chauhan, J. Cui, C. Wong, D. K. Harris, H. Wei, H.-S. Han, D. Fukumura, R. K. Jain, and M. G. Bawendi, “Compact high-quality CdSe-CdS core-shell nanocrystals with narrow emission linewidths and suppressed blinking,” Nat. Mater. 12(5), 445–451 (2013).
[PubMed]

Dai, X.

X. Dai, Z. Zhang, Y. Jin, Y. Niu, H. Cao, X. Liang, L. Chen, J. Wang, and X. Peng, “Solution-processed, high-performance light-emitting diodes based on quantum dots,” Nature 515(7525), 96–99 (2014).
[PubMed]

Das, A.

P. Maity, T. Debnath, T. Banerjee, A. Das, and H. N. Ghosh, “Charge delocalization in the cascade band structure CdS/CdSe and CdS/CdTe core–shell sensitized with Re(I)–polypyridyl complex,” J. Phys. Chem. C 120, 10051–10061 (2016).

C. M. Tyrakowski, A. Shamirian, C. E. Rowland, H. Shen, A. Das, R. D. Schaller, and P. T. Snee, “Bright type II quantum dots,” Chem. Mater. 27, 7276–7281 (2015).

Debnath, T.

P. Maity, T. Debnath, T. Banerjee, A. Das, and H. N. Ghosh, “Charge delocalization in the cascade band structure CdS/CdSe and CdS/CdTe core–shell sensitized with Re(I)–polypyridyl complex,” J. Phys. Chem. C 120, 10051–10061 (2016).

P. Maity, T. Debnath, and H. N. Ghosh, “Ultrafast charge carrier delocalization in CdSe/CdS quasi-type II and CdS/CdSe inverted type I core–shell: a structural analysis through carrier-quenching study,” J. Phys. Chem. C 119, 26202–26211 (2015).

Delerue, C.

W. H. Evers, J. M. Schins, M. Aerts, A. Kulkarni, P. Capiod, M. Berthe, B. Grandidier, C. Delerue, H. S. J. van der Zant, C. van Overbeek, J. L. Peters, D. Vanmaekelbergh, and L. D. A. Siebbeles, “High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds,” Nat. Commun. 6, 8195 (2015).
[PubMed]

Donega, Cde. M.

E. Groeneveld, L. Witteman, M. Lefferts, X. Ke, S. Bals, G. Van Tendeloo, and Cde. M. Donega, “Tailoring ZnSe-CdSe colloidal quantum dots via cation exchange: from core/shell to alloy nanocrystals,” ACS Nano 7(9), 7913–7930 (2013).
[PubMed]

Du, F.

F. Du, H. Zhang, X. Du, J. Zhu, and X. Zhong, “Controllable synthesis and optical properties of CdS/CdSe hetero-nanostructures with various dimensionalities,” Mater. Chem. Phys. 121, 118–124 (2010).

Du, X.

F. Du, H. Zhang, X. Du, J. Zhu, and X. Zhong, “Controllable synthesis and optical properties of CdS/CdSe hetero-nanostructures with various dimensionalities,” Mater. Chem. Phys. 121, 118–124 (2010).

Dubertret, B.

D. Canneson, L. Biadala, S. Buil, X. Quélin, C. Javaux, B. Dubertret, and J. P. Hermier, “Blinking suppression and biexcitonic emission in thick-shell CdSe/CdS nanocrystals at cryogenic temperature,” Phys. Rev. B 89, 035303 (2014).

B. Mahler, P. Spinicelli, S. Buil, X. Quelin, J.-P. Hermier, and B. Dubertret, “Towards non-blinking colloidal quantum dots,” Nat. Mater. 7(8), 659–664 (2008).
[PubMed]

El-Sayed, M. A.

C. Burda, X. Chen, R. Narayanan, and M. A. El-Sayed, “Chemistry and properties of nanocrystals of different shapes,” Chem. Rev. 105(4), 1025–1102 (2005).
[PubMed]

Evers, W. H.

W. H. Evers, J. M. Schins, M. Aerts, A. Kulkarni, P. Capiod, M. Berthe, B. Grandidier, C. Delerue, H. S. J. van der Zant, C. van Overbeek, J. L. Peters, D. Vanmaekelbergh, and L. D. A. Siebbeles, “High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds,” Nat. Commun. 6, 8195 (2015).
[PubMed]

Fang, W.

H. Qin, Y. Niu, R. Meng, X. Lin, R. Lai, W. Fang, and X. Peng, “Single-dot spectroscopy of zinc-blende CdSe/CdS core/shell nanocrystals: nonblinking and correlation with ensemble measurements,” J. Am. Chem. Soc. 136(1), 179–187 (2014).
[PubMed]

Fukumura, D.

O. Chen, J. Zhao, V. P. Chauhan, J. Cui, C. Wong, D. K. Harris, H. Wei, H.-S. Han, D. Fukumura, R. K. Jain, and M. G. Bawendi, “Compact high-quality CdSe-CdS core-shell nanocrystals with narrow emission linewidths and suppressed blinking,” Nat. Mater. 12(5), 445–451 (2013).
[PubMed]

Ghosh, H. N.

P. Maity, T. Debnath, T. Banerjee, A. Das, and H. N. Ghosh, “Charge delocalization in the cascade band structure CdS/CdSe and CdS/CdTe core–shell sensitized with Re(I)–polypyridyl complex,” J. Phys. Chem. C 120, 10051–10061 (2016).

P. Maity, T. Debnath, and H. N. Ghosh, “Ultrafast charge carrier delocalization in CdSe/CdS quasi-type II and CdS/CdSe inverted type I core–shell: a structural analysis through carrier-quenching study,” J. Phys. Chem. C 119, 26202–26211 (2015).

Gong, J.

Q. Li, H. Meng, P. Zhou, Y. Zheng, J. Wang, J. Yu, and J. Gong, “Zn1–xCdxS solid solutions with controlled bandgap and enhanced visible-light photocatalytic H2-production activity,” ACS Catal. 3, 882–889 (2013).

Grandidier, B.

W. H. Evers, J. M. Schins, M. Aerts, A. Kulkarni, P. Capiod, M. Berthe, B. Grandidier, C. Delerue, H. S. J. van der Zant, C. van Overbeek, J. L. Peters, D. Vanmaekelbergh, and L. D. A. Siebbeles, “High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds,” Nat. Commun. 6, 8195 (2015).
[PubMed]

Groeneveld, E.

E. Groeneveld, L. Witteman, M. Lefferts, X. Ke, S. Bals, G. Van Tendeloo, and Cde. M. Donega, “Tailoring ZnSe-CdSe colloidal quantum dots via cation exchange: from core/shell to alloy nanocrystals,” ACS Nano 7(9), 7913–7930 (2013).
[PubMed]

Guo, W.

J. J. Li, Y. A. Wang, W. Guo, J. C. Keay, T. D. Mishima, M. B. Johnson, and X. Peng, “Large-scale synthesis of nearly monodisperse CdSe/CdS core/shell nanocrystals using air-stable reagents via successive ion layer adsorption and reaction,” J. Am. Chem. Soc. 125(41), 12567–12575 (2003).
[PubMed]

Halpert, J. E.

V. Wood, M. J. Panzer, J. M. Caruge, J. E. Halpert, M. G. Bawendi, and V. Bulović, “Air-stable operation of transparent, colloidal quantum dot based LEDs with a unipolar device architecture,” Nano Lett. 10(1), 24–29 (2010).
[PubMed]

Han, H.-S.

O. Chen, J. Zhao, V. P. Chauhan, J. Cui, C. Wong, D. K. Harris, H. Wei, H.-S. Han, D. Fukumura, R. K. Jain, and M. G. Bawendi, “Compact high-quality CdSe-CdS core-shell nanocrystals with narrow emission linewidths and suppressed blinking,” Nat. Mater. 12(5), 445–451 (2013).
[PubMed]

Han, J. Y.

K.-S. Cho, E. K. Lee, W.-J. Joo, E. Jang, T.-H. Kim, S. J. Lee, S.-J. Kwon, J. Y. Han, B.-K. Kim, B. L. Choi, and J. M. Kim, “High-performance crosslinked colloidal quantum-dot light-emitting diodes,” Nat. Photonics 3, 341–345 (2009).

Harris, D. K.

O. Chen, J. Zhao, V. P. Chauhan, J. Cui, C. Wong, D. K. Harris, H. Wei, H.-S. Han, D. Fukumura, R. K. Jain, and M. G. Bawendi, “Compact high-quality CdSe-CdS core-shell nanocrystals with narrow emission linewidths and suppressed blinking,” Nat. Mater. 12(5), 445–451 (2013).
[PubMed]

He, X.

X. Jin, W. Sun, Z. Chen, T. Wei, C. Chen, X. He, Y. Yuan, Y. Li, and Q. Li, “Exciton generation/dissociation/charge-transfer enhancement in inorganic/organic hybrid solar cells by robust single nanocrystalline LnPxOy (Ln = Eu, Y) doping,” ACS Appl. Mater. Interfaces 6(11), 8771–8781 (2014).
[PubMed]

Hermier, J. P.

D. Canneson, L. Biadala, S. Buil, X. Quélin, C. Javaux, B. Dubertret, and J. P. Hermier, “Blinking suppression and biexcitonic emission in thick-shell CdSe/CdS nanocrystals at cryogenic temperature,” Phys. Rev. B 89, 035303 (2014).

Hermier, J.-P.

B. Mahler, P. Spinicelli, S. Buil, X. Quelin, J.-P. Hermier, and B. Dubertret, “Towards non-blinking colloidal quantum dots,” Nat. Mater. 7(8), 659–664 (2008).
[PubMed]

Hou, Y.

Z. Pan, H. Zhang, K. Cheng, Y. Hou, J. Hua, and X. Zhong, “Highly efficient inverted type-I CdS/CdSe core/shell structure QD-sensitized solar cells,” ACS Nano 6(5), 3982–3991 (2012).
[PubMed]

Hua, J.

Z. Pan, H. Zhang, K. Cheng, Y. Hou, J. Hua, and X. Zhong, “Highly efficient inverted type-I CdS/CdSe core/shell structure QD-sensitized solar cells,” ACS Nano 6(5), 3982–3991 (2012).
[PubMed]

Hyvonen, J.

H. Shen, X. Bai, A. Wang, H. Wang, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “High-efficient deep-blue light-emitting diodes by using high quality ZnxCd1-xS/ZnS core/shell quantum dots,” Adv. Funct. Mater. 24, 2367–2373 (2014).

H. Shen, S. Wang, H. Wang, J. Niu, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “Highly efficient blue-green quantum dot light-emitting diodes using stable low-cadmium quaternary-alloy ZnCdSSe/ZnS core/shell nanocrystals,” ACS Appl. Mater. Interfaces 5(10), 4260–4265 (2013).
[PubMed]

Jain, R. K.

O. Chen, J. Zhao, V. P. Chauhan, J. Cui, C. Wong, D. K. Harris, H. Wei, H.-S. Han, D. Fukumura, R. K. Jain, and M. G. Bawendi, “Compact high-quality CdSe-CdS core-shell nanocrystals with narrow emission linewidths and suppressed blinking,” Nat. Mater. 12(5), 445–451 (2013).
[PubMed]

Jang, E.

K.-S. Cho, E. K. Lee, W.-J. Joo, E. Jang, T.-H. Kim, S. J. Lee, S.-J. Kwon, J. Y. Han, B.-K. Kim, B. L. Choi, and J. M. Kim, “High-performance crosslinked colloidal quantum-dot light-emitting diodes,” Nat. Photonics 3, 341–345 (2009).

Javaux, C.

D. Canneson, L. Biadala, S. Buil, X. Quélin, C. Javaux, B. Dubertret, and J. P. Hermier, “Blinking suppression and biexcitonic emission in thick-shell CdSe/CdS nanocrystals at cryogenic temperature,” Phys. Rev. B 89, 035303 (2014).

Jeong, B. G.

B. G. Jeong, Y.-S. Park, J. H. Chang, I. Cho, J. K. Kim, H. Kim, K. Char, J. Cho, V. I. Klimov, P. Park, D. C. Lee, and W. K. Bae, “Colloidal spherical quantum wells with near-unity photoluminescence quantum yield and suppressed blinking,” ACS Nano 10, 9297–9305 (2016).
[PubMed]

Jin, X.

Q. H. Li, X. Jin, Y. Yang, H. N. Wang, H. J. Xu, Y. Y. Cheng, T. H. Wei, Y. C. Qin, X. B. Luo, W. F. Sun, and S. L. Luo, “Nd2(S, Se, Te)3 colloidal quantum dots: synthesis, energy level alignment, charge transfer dynamics, and their applications to solar cells,” Adv. Funct. Mater. 26, 254–266 (2016).

X. Jin, W. Sun, S. Luo, L. Shao, J. Zhang, X. Luo, T. Wei, Y. Qin, Y. Song, and Q. Li, “Energy gradient architectured praseodymium chalcogenide quantum dot solar cells: towards unidirectionally funneling energy transfer,” J. Mater. Chem. A Mater. Energy Sustain. 3, 23876–23887 (2015).

Q. Li, X. Jin, X. Yang, C. Chen, Z. Chen, Y. Qin, T.-h. Wei, and W. Sun, “Reducing the excess energy offset in organic/inorganic hybrid solar cells: Toward faster electron transfer,” Appl. Catal. B 162, 524–531 (2015).

X. Jin, W. Sun, Z. Chen, T. Wei, C. Chen, X. He, Y. Yuan, Y. Li, and Q. Li, “Exciton generation/dissociation/charge-transfer enhancement in inorganic/organic hybrid solar cells by robust single nanocrystalline LnPxOy (Ln = Eu, Y) doping,” ACS Appl. Mater. Interfaces 6(11), 8771–8781 (2014).
[PubMed]

Jin, Y.

X. Dai, Z. Zhang, Y. Jin, Y. Niu, H. Cao, X. Liang, L. Chen, J. Wang, and X. Peng, “Solution-processed, high-performance light-emitting diodes based on quantum dots,” Nature 515(7525), 96–99 (2014).
[PubMed]

Johnson, M. B.

J. J. Li, Y. A. Wang, W. Guo, J. C. Keay, T. D. Mishima, M. B. Johnson, and X. Peng, “Large-scale synthesis of nearly monodisperse CdSe/CdS core/shell nanocrystals using air-stable reagents via successive ion layer adsorption and reaction,” J. Am. Chem. Soc. 125(41), 12567–12575 (2003).
[PubMed]

Joo, W.-J.

K.-S. Cho, E. K. Lee, W.-J. Joo, E. Jang, T.-H. Kim, S. J. Lee, S.-J. Kwon, J. Y. Han, B.-K. Kim, B. L. Choi, and J. M. Kim, “High-performance crosslinked colloidal quantum-dot light-emitting diodes,” Nat. Photonics 3, 341–345 (2009).

Kadavanich, A.

X. Peng, L. Manna, W. Yang, J. Wickham, E. Scher, A. Kadavanich, and A. P. Alivisatos, “Shape control of CdSe nanocrystals,” Nature 404(6773), 59–61 (2000).
[PubMed]

Ke, X.

E. Groeneveld, L. Witteman, M. Lefferts, X. Ke, S. Bals, G. Van Tendeloo, and Cde. M. Donega, “Tailoring ZnSe-CdSe colloidal quantum dots via cation exchange: from core/shell to alloy nanocrystals,” ACS Nano 7(9), 7913–7930 (2013).
[PubMed]

Keay, J. C.

J. J. Li, Y. A. Wang, W. Guo, J. C. Keay, T. D. Mishima, M. B. Johnson, and X. Peng, “Large-scale synthesis of nearly monodisperse CdSe/CdS core/shell nanocrystals using air-stable reagents via successive ion layer adsorption and reaction,” J. Am. Chem. Soc. 125(41), 12567–12575 (2003).
[PubMed]

Kim, B.-K.

K.-S. Cho, E. K. Lee, W.-J. Joo, E. Jang, T.-H. Kim, S. J. Lee, S.-J. Kwon, J. Y. Han, B.-K. Kim, B. L. Choi, and J. M. Kim, “High-performance crosslinked colloidal quantum-dot light-emitting diodes,” Nat. Photonics 3, 341–345 (2009).

Kim, H.

B. G. Jeong, Y.-S. Park, J. H. Chang, I. Cho, J. K. Kim, H. Kim, K. Char, J. Cho, V. I. Klimov, P. Park, D. C. Lee, and W. K. Bae, “Colloidal spherical quantum wells with near-unity photoluminescence quantum yield and suppressed blinking,” ACS Nano 10, 9297–9305 (2016).
[PubMed]

Kim, J. K.

B. G. Jeong, Y.-S. Park, J. H. Chang, I. Cho, J. K. Kim, H. Kim, K. Char, J. Cho, V. I. Klimov, P. Park, D. C. Lee, and W. K. Bae, “Colloidal spherical quantum wells with near-unity photoluminescence quantum yield and suppressed blinking,” ACS Nano 10, 9297–9305 (2016).
[PubMed]

Kim, J. M.

K.-S. Cho, E. K. Lee, W.-J. Joo, E. Jang, T.-H. Kim, S. J. Lee, S.-J. Kwon, J. Y. Han, B.-K. Kim, B. L. Choi, and J. M. Kim, “High-performance crosslinked colloidal quantum-dot light-emitting diodes,” Nat. Photonics 3, 341–345 (2009).

Kim, T.-H.

K.-S. Cho, E. K. Lee, W.-J. Joo, E. Jang, T.-H. Kim, S. J. Lee, S.-J. Kwon, J. Y. Han, B.-K. Kim, B. L. Choi, and J. M. Kim, “High-performance crosslinked colloidal quantum-dot light-emitting diodes,” Nat. Photonics 3, 341–345 (2009).

Klimov, V. I.

B. G. Jeong, Y.-S. Park, J. H. Chang, I. Cho, J. K. Kim, H. Kim, K. Char, J. Cho, V. I. Klimov, P. Park, D. C. Lee, and W. K. Bae, “Colloidal spherical quantum wells with near-unity photoluminescence quantum yield and suppressed blinking,” ACS Nano 10, 9297–9305 (2016).
[PubMed]

Knoll, W.

X. Zhong, R. Xie, Y. Zhang, T. Basché, and W. Knoll, “High-quality violet- to red-emitting ZnSe/CdSe core/shell nanocrystals,” Chem. Mater. 17, 4038–4042 (2005).

Ko, H.

K.-H. Lee, J.-H. Lee, W.-S. Song, H. Ko, C. Lee, J.-H. Lee, and H. Yang, “Highly efficient, color-pure, color-stable blue quantum dot light-emitting devices,” ACS Nano 7(8), 7295–7302 (2013).
[PubMed]

Kulkarni, A.

W. H. Evers, J. M. Schins, M. Aerts, A. Kulkarni, P. Capiod, M. Berthe, B. Grandidier, C. Delerue, H. S. J. van der Zant, C. van Overbeek, J. L. Peters, D. Vanmaekelbergh, and L. D. A. Siebbeles, “High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds,” Nat. Commun. 6, 8195 (2015).
[PubMed]

Kumar, H.

H. Kumar, P. B. Barman, and R. R. Singh, “Low-Temperature growth of inverted hexagonal ZnS/CdS quantum dots: functional and luminescence properties,” J. Electron. Mater. 44, 675–681 (2014).

Kwak, J.

J. Kwak, J. Lim, M. Park, S. Lee, K. Char, and C. Lee, “High-power genuine ultraviolet light-emitting diodes based on colloidal nanocrystal quantum dots,” Nano Lett. 15(6), 3793–3799 (2015).
[PubMed]

J. Kwak, W. K. Bae, D. Lee, I. Park, J. Lim, M. Park, H. Cho, H. Woo, D. Y. Yoon, K. Char, S. Lee, and C. Lee, “Bright and efficient full-color colloidal quantum dot light-emitting diodes using an inverted device structure,” Nano Lett. 12(5), 2362–2366 (2012).
[PubMed]

Kwon, S.-J.

K.-S. Cho, E. K. Lee, W.-J. Joo, E. Jang, T.-H. Kim, S. J. Lee, S.-J. Kwon, J. Y. Han, B.-K. Kim, B. L. Choi, and J. M. Kim, “High-performance crosslinked colloidal quantum-dot light-emitting diodes,” Nat. Photonics 3, 341–345 (2009).

Lai, R.

Y. Niu, C. Pu, R. Lai, R. Meng, W. Lin, H. Qin, and X. Peng, “One-pot/three-step synthesis of zinc-blende CdSe/CdS core/shell nanocrystals with thick shells,” Nano Res. 10, 1149–1162 (2017).

H. Qin, Y. Niu, R. Meng, X. Lin, R. Lai, W. Fang, and X. Peng, “Single-dot spectroscopy of zinc-blende CdSe/CdS core/shell nanocrystals: nonblinking and correlation with ensemble measurements,” J. Am. Chem. Soc. 136(1), 179–187 (2014).
[PubMed]

W. Nan, Y. Niu, H. Qin, F. Cui, Y. Yang, R. Lai, W. Lin, and X. Peng, “Crystal structure control of zinc-blende CdSe/CdS core/shell nanocrystals: synthesis and structure-dependent optical properties,” J. Am. Chem. Soc. 134(48), 19685–19693 (2012).
[PubMed]

Lee, C.

J. Kwak, J. Lim, M. Park, S. Lee, K. Char, and C. Lee, “High-power genuine ultraviolet light-emitting diodes based on colloidal nanocrystal quantum dots,” Nano Lett. 15(6), 3793–3799 (2015).
[PubMed]

K.-H. Lee, J.-H. Lee, W.-S. Song, H. Ko, C. Lee, J.-H. Lee, and H. Yang, “Highly efficient, color-pure, color-stable blue quantum dot light-emitting devices,” ACS Nano 7(8), 7295–7302 (2013).
[PubMed]

J. Kwak, W. K. Bae, D. Lee, I. Park, J. Lim, M. Park, H. Cho, H. Woo, D. Y. Yoon, K. Char, S. Lee, and C. Lee, “Bright and efficient full-color colloidal quantum dot light-emitting diodes using an inverted device structure,” Nano Lett. 12(5), 2362–2366 (2012).
[PubMed]

Lee, D.

J. Kwak, W. K. Bae, D. Lee, I. Park, J. Lim, M. Park, H. Cho, H. Woo, D. Y. Yoon, K. Char, S. Lee, and C. Lee, “Bright and efficient full-color colloidal quantum dot light-emitting diodes using an inverted device structure,” Nano Lett. 12(5), 2362–2366 (2012).
[PubMed]

Lee, D. C.

B. G. Jeong, Y.-S. Park, J. H. Chang, I. Cho, J. K. Kim, H. Kim, K. Char, J. Cho, V. I. Klimov, P. Park, D. C. Lee, and W. K. Bae, “Colloidal spherical quantum wells with near-unity photoluminescence quantum yield and suppressed blinking,” ACS Nano 10, 9297–9305 (2016).
[PubMed]

Lee, E. K.

K.-S. Cho, E. K. Lee, W.-J. Joo, E. Jang, T.-H. Kim, S. J. Lee, S.-J. Kwon, J. Y. Han, B.-K. Kim, B. L. Choi, and J. M. Kim, “High-performance crosslinked colloidal quantum-dot light-emitting diodes,” Nat. Photonics 3, 341–345 (2009).

Lee, J.-H.

K.-H. Lee, J.-H. Lee, W.-S. Song, H. Ko, C. Lee, J.-H. Lee, and H. Yang, “Highly efficient, color-pure, color-stable blue quantum dot light-emitting devices,” ACS Nano 7(8), 7295–7302 (2013).
[PubMed]

K.-H. Lee, J.-H. Lee, W.-S. Song, H. Ko, C. Lee, J.-H. Lee, and H. Yang, “Highly efficient, color-pure, color-stable blue quantum dot light-emitting devices,” ACS Nano 7(8), 7295–7302 (2013).
[PubMed]

Lee, K.-H.

K.-H. Lee, J.-H. Lee, W.-S. Song, H. Ko, C. Lee, J.-H. Lee, and H. Yang, “Highly efficient, color-pure, color-stable blue quantum dot light-emitting devices,” ACS Nano 7(8), 7295–7302 (2013).
[PubMed]

Lee, S.

J. Kwak, J. Lim, M. Park, S. Lee, K. Char, and C. Lee, “High-power genuine ultraviolet light-emitting diodes based on colloidal nanocrystal quantum dots,” Nano Lett. 15(6), 3793–3799 (2015).
[PubMed]

J. Kwak, W. K. Bae, D. Lee, I. Park, J. Lim, M. Park, H. Cho, H. Woo, D. Y. Yoon, K. Char, S. Lee, and C. Lee, “Bright and efficient full-color colloidal quantum dot light-emitting diodes using an inverted device structure,” Nano Lett. 12(5), 2362–2366 (2012).
[PubMed]

W. K. Bae, M. K. Nam, K. Char, and S. Lee, “Gram-scale one-pot synthesis of highly luminescent blue emitting Cd1−xZnxS/ZnS nanocrystals,” Chem. Mater. 20, 5307–5313 (2008).

Lee, S. J.

K.-S. Cho, E. K. Lee, W.-J. Joo, E. Jang, T.-H. Kim, S. J. Lee, S.-J. Kwon, J. Y. Han, B.-K. Kim, B. L. Choi, and J. M. Kim, “High-performance crosslinked colloidal quantum-dot light-emitting diodes,” Nat. Photonics 3, 341–345 (2009).

Lefferts, M.

E. Groeneveld, L. Witteman, M. Lefferts, X. Ke, S. Bals, G. Van Tendeloo, and Cde. M. Donega, “Tailoring ZnSe-CdSe colloidal quantum dots via cation exchange: from core/shell to alloy nanocrystals,” ACS Nano 7(9), 7913–7930 (2013).
[PubMed]

Li, J. J.

J. J. Li, Y. A. Wang, W. Guo, J. C. Keay, T. D. Mishima, M. B. Johnson, and X. Peng, “Large-scale synthesis of nearly monodisperse CdSe/CdS core/shell nanocrystals using air-stable reagents via successive ion layer adsorption and reaction,” J. Am. Chem. Soc. 125(41), 12567–12575 (2003).
[PubMed]

Li, L. S.

H. Shen, X. Bai, A. Wang, H. Wang, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “High-efficient deep-blue light-emitting diodes by using high quality ZnxCd1-xS/ZnS core/shell quantum dots,” Adv. Funct. Mater. 24, 2367–2373 (2014).

H. Shen, S. Wang, H. Wang, J. Niu, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “Highly efficient blue-green quantum dot light-emitting diodes using stable low-cadmium quaternary-alloy ZnCdSSe/ZnS core/shell nanocrystals,” ACS Appl. Mater. Interfaces 5(10), 4260–4265 (2013).
[PubMed]

Li, Q.

Q. Li, X. Jin, X. Yang, C. Chen, Z. Chen, Y. Qin, T.-h. Wei, and W. Sun, “Reducing the excess energy offset in organic/inorganic hybrid solar cells: Toward faster electron transfer,” Appl. Catal. B 162, 524–531 (2015).

X. Jin, W. Sun, S. Luo, L. Shao, J. Zhang, X. Luo, T. Wei, Y. Qin, Y. Song, and Q. Li, “Energy gradient architectured praseodymium chalcogenide quantum dot solar cells: towards unidirectionally funneling energy transfer,” J. Mater. Chem. A Mater. Energy Sustain. 3, 23876–23887 (2015).

X. Jin, W. Sun, Z. Chen, T. Wei, C. Chen, X. He, Y. Yuan, Y. Li, and Q. Li, “Exciton generation/dissociation/charge-transfer enhancement in inorganic/organic hybrid solar cells by robust single nanocrystalline LnPxOy (Ln = Eu, Y) doping,” ACS Appl. Mater. Interfaces 6(11), 8771–8781 (2014).
[PubMed]

Q. Li, H. Meng, P. Zhou, Y. Zheng, J. Wang, J. Yu, and J. Gong, “Zn1–xCdxS solid solutions with controlled bandgap and enhanced visible-light photocatalytic H2-production activity,” ACS Catal. 3, 882–889 (2013).

Li, Q. H.

Q. H. Li, X. Jin, Y. Yang, H. N. Wang, H. J. Xu, Y. Y. Cheng, T. H. Wei, Y. C. Qin, X. B. Luo, W. F. Sun, and S. L. Luo, “Nd2(S, Se, Te)3 colloidal quantum dots: synthesis, energy level alignment, charge transfer dynamics, and their applications to solar cells,” Adv. Funct. Mater. 26, 254–266 (2016).

Li, Y.

X. Jin, W. Sun, Z. Chen, T. Wei, C. Chen, X. He, Y. Yuan, Y. Li, and Q. Li, “Exciton generation/dissociation/charge-transfer enhancement in inorganic/organic hybrid solar cells by robust single nanocrystalline LnPxOy (Ln = Eu, Y) doping,” ACS Appl. Mater. Interfaces 6(11), 8771–8781 (2014).
[PubMed]

Liang, X.

X. Dai, Z. Zhang, Y. Jin, Y. Niu, H. Cao, X. Liang, L. Chen, J. Wang, and X. Peng, “Solution-processed, high-performance light-emitting diodes based on quantum dots,” Nature 515(7525), 96–99 (2014).
[PubMed]

Lim, J.

J. Kwak, J. Lim, M. Park, S. Lee, K. Char, and C. Lee, “High-power genuine ultraviolet light-emitting diodes based on colloidal nanocrystal quantum dots,” Nano Lett. 15(6), 3793–3799 (2015).
[PubMed]

J. Kwak, W. K. Bae, D. Lee, I. Park, J. Lim, M. Park, H. Cho, H. Woo, D. Y. Yoon, K. Char, S. Lee, and C. Lee, “Bright and efficient full-color colloidal quantum dot light-emitting diodes using an inverted device structure,” Nano Lett. 12(5), 2362–2366 (2012).
[PubMed]

Lin, W.

Y. Niu, C. Pu, R. Lai, R. Meng, W. Lin, H. Qin, and X. Peng, “One-pot/three-step synthesis of zinc-blende CdSe/CdS core/shell nanocrystals with thick shells,” Nano Res. 10, 1149–1162 (2017).

W. Nan, Y. Niu, H. Qin, F. Cui, Y. Yang, R. Lai, W. Lin, and X. Peng, “Crystal structure control of zinc-blende CdSe/CdS core/shell nanocrystals: synthesis and structure-dependent optical properties,” J. Am. Chem. Soc. 134(48), 19685–19693 (2012).
[PubMed]

Lin, X.

H. Qin, Y. Niu, R. Meng, X. Lin, R. Lai, W. Fang, and X. Peng, “Single-dot spectroscopy of zinc-blende CdSe/CdS core/shell nanocrystals: nonblinking and correlation with ensemble measurements,” J. Am. Chem. Soc. 136(1), 179–187 (2014).
[PubMed]

Luo, S.

X. Jin, W. Sun, S. Luo, L. Shao, J. Zhang, X. Luo, T. Wei, Y. Qin, Y. Song, and Q. Li, “Energy gradient architectured praseodymium chalcogenide quantum dot solar cells: towards unidirectionally funneling energy transfer,” J. Mater. Chem. A Mater. Energy Sustain. 3, 23876–23887 (2015).

Luo, S. L.

Q. H. Li, X. Jin, Y. Yang, H. N. Wang, H. J. Xu, Y. Y. Cheng, T. H. Wei, Y. C. Qin, X. B. Luo, W. F. Sun, and S. L. Luo, “Nd2(S, Se, Te)3 colloidal quantum dots: synthesis, energy level alignment, charge transfer dynamics, and their applications to solar cells,” Adv. Funct. Mater. 26, 254–266 (2016).

Luo, X.

X. Jin, W. Sun, S. Luo, L. Shao, J. Zhang, X. Luo, T. Wei, Y. Qin, Y. Song, and Q. Li, “Energy gradient architectured praseodymium chalcogenide quantum dot solar cells: towards unidirectionally funneling energy transfer,” J. Mater. Chem. A Mater. Energy Sustain. 3, 23876–23887 (2015).

Luo, X. B.

Q. H. Li, X. Jin, Y. Yang, H. N. Wang, H. J. Xu, Y. Y. Cheng, T. H. Wei, Y. C. Qin, X. B. Luo, W. F. Sun, and S. L. Luo, “Nd2(S, Se, Te)3 colloidal quantum dots: synthesis, energy level alignment, charge transfer dynamics, and their applications to solar cells,” Adv. Funct. Mater. 26, 254–266 (2016).

Mahler, B.

B. Mahler, P. Spinicelli, S. Buil, X. Quelin, J.-P. Hermier, and B. Dubertret, “Towards non-blinking colloidal quantum dots,” Nat. Mater. 7(8), 659–664 (2008).
[PubMed]

Maity, P.

P. Maity, T. Debnath, T. Banerjee, A. Das, and H. N. Ghosh, “Charge delocalization in the cascade band structure CdS/CdSe and CdS/CdTe core–shell sensitized with Re(I)–polypyridyl complex,” J. Phys. Chem. C 120, 10051–10061 (2016).

P. Maity, T. Debnath, and H. N. Ghosh, “Ultrafast charge carrier delocalization in CdSe/CdS quasi-type II and CdS/CdSe inverted type I core–shell: a structural analysis through carrier-quenching study,” J. Phys. Chem. C 119, 26202–26211 (2015).

Manna, L.

X. Peng, L. Manna, W. Yang, J. Wickham, E. Scher, A. Kadavanich, and A. P. Alivisatos, “Shape control of CdSe nanocrystals,” Nature 404(6773), 59–61 (2000).
[PubMed]

Meng, H.

Q. Li, H. Meng, P. Zhou, Y. Zheng, J. Wang, J. Yu, and J. Gong, “Zn1–xCdxS solid solutions with controlled bandgap and enhanced visible-light photocatalytic H2-production activity,” ACS Catal. 3, 882–889 (2013).

Meng, R.

Y. Niu, C. Pu, R. Lai, R. Meng, W. Lin, H. Qin, and X. Peng, “One-pot/three-step synthesis of zinc-blende CdSe/CdS core/shell nanocrystals with thick shells,” Nano Res. 10, 1149–1162 (2017).

H. Qin, Y. Niu, R. Meng, X. Lin, R. Lai, W. Fang, and X. Peng, “Single-dot spectroscopy of zinc-blende CdSe/CdS core/shell nanocrystals: nonblinking and correlation with ensemble measurements,” J. Am. Chem. Soc. 136(1), 179–187 (2014).
[PubMed]

Mishima, T. D.

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Y. Niu, C. Pu, R. Lai, R. Meng, W. Lin, H. Qin, and X. Peng, “One-pot/three-step synthesis of zinc-blende CdSe/CdS core/shell nanocrystals with thick shells,” Nano Res. 10, 1149–1162 (2017).

H. Qin, Y. Niu, R. Meng, X. Lin, R. Lai, W. Fang, and X. Peng, “Single-dot spectroscopy of zinc-blende CdSe/CdS core/shell nanocrystals: nonblinking and correlation with ensemble measurements,” J. Am. Chem. Soc. 136(1), 179–187 (2014).
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Y. Niu, C. Pu, R. Lai, R. Meng, W. Lin, H. Qin, and X. Peng, “One-pot/three-step synthesis of zinc-blende CdSe/CdS core/shell nanocrystals with thick shells,” Nano Res. 10, 1149–1162 (2017).

H. Qin, Y. Niu, R. Meng, X. Lin, R. Lai, W. Fang, and X. Peng, “Single-dot spectroscopy of zinc-blende CdSe/CdS core/shell nanocrystals: nonblinking and correlation with ensemble measurements,” J. Am. Chem. Soc. 136(1), 179–187 (2014).
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W. Nan, Y. Niu, H. Qin, F. Cui, Y. Yang, R. Lai, W. Lin, and X. Peng, “Crystal structure control of zinc-blende CdSe/CdS core/shell nanocrystals: synthesis and structure-dependent optical properties,” J. Am. Chem. Soc. 134(48), 19685–19693 (2012).
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X. Peng, L. Manna, W. Yang, J. Wickham, E. Scher, A. Kadavanich, and A. P. Alivisatos, “Shape control of CdSe nanocrystals,” Nature 404(6773), 59–61 (2000).
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Peters, J. L.

W. H. Evers, J. M. Schins, M. Aerts, A. Kulkarni, P. Capiod, M. Berthe, B. Grandidier, C. Delerue, H. S. J. van der Zant, C. van Overbeek, J. L. Peters, D. Vanmaekelbergh, and L. D. A. Siebbeles, “High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds,” Nat. Commun. 6, 8195 (2015).
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Y. Niu, C. Pu, R. Lai, R. Meng, W. Lin, H. Qin, and X. Peng, “One-pot/three-step synthesis of zinc-blende CdSe/CdS core/shell nanocrystals with thick shells,” Nano Res. 10, 1149–1162 (2017).

Qian, L.

H. Shen, X. Bai, A. Wang, H. Wang, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “High-efficient deep-blue light-emitting diodes by using high quality ZnxCd1-xS/ZnS core/shell quantum dots,” Adv. Funct. Mater. 24, 2367–2373 (2014).

H. Shen, S. Wang, H. Wang, J. Niu, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “Highly efficient blue-green quantum dot light-emitting diodes using stable low-cadmium quaternary-alloy ZnCdSSe/ZnS core/shell nanocrystals,” ACS Appl. Mater. Interfaces 5(10), 4260–4265 (2013).
[PubMed]

Qin, H.

Y. Niu, C. Pu, R. Lai, R. Meng, W. Lin, H. Qin, and X. Peng, “One-pot/three-step synthesis of zinc-blende CdSe/CdS core/shell nanocrystals with thick shells,” Nano Res. 10, 1149–1162 (2017).

H. Qin, Y. Niu, R. Meng, X. Lin, R. Lai, W. Fang, and X. Peng, “Single-dot spectroscopy of zinc-blende CdSe/CdS core/shell nanocrystals: nonblinking and correlation with ensemble measurements,” J. Am. Chem. Soc. 136(1), 179–187 (2014).
[PubMed]

W. Nan, Y. Niu, H. Qin, F. Cui, Y. Yang, R. Lai, W. Lin, and X. Peng, “Crystal structure control of zinc-blende CdSe/CdS core/shell nanocrystals: synthesis and structure-dependent optical properties,” J. Am. Chem. Soc. 134(48), 19685–19693 (2012).
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Qin, Y.

Q. Li, X. Jin, X. Yang, C. Chen, Z. Chen, Y. Qin, T.-h. Wei, and W. Sun, “Reducing the excess energy offset in organic/inorganic hybrid solar cells: Toward faster electron transfer,” Appl. Catal. B 162, 524–531 (2015).

X. Jin, W. Sun, S. Luo, L. Shao, J. Zhang, X. Luo, T. Wei, Y. Qin, Y. Song, and Q. Li, “Energy gradient architectured praseodymium chalcogenide quantum dot solar cells: towards unidirectionally funneling energy transfer,” J. Mater. Chem. A Mater. Energy Sustain. 3, 23876–23887 (2015).

Qin, Y. C.

Q. H. Li, X. Jin, Y. Yang, H. N. Wang, H. J. Xu, Y. Y. Cheng, T. H. Wei, Y. C. Qin, X. B. Luo, W. F. Sun, and S. L. Luo, “Nd2(S, Se, Te)3 colloidal quantum dots: synthesis, energy level alignment, charge transfer dynamics, and their applications to solar cells,” Adv. Funct. Mater. 26, 254–266 (2016).

Quelin, X.

B. Mahler, P. Spinicelli, S. Buil, X. Quelin, J.-P. Hermier, and B. Dubertret, “Towards non-blinking colloidal quantum dots,” Nat. Mater. 7(8), 659–664 (2008).
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Rowland, C. E.

C. M. Tyrakowski, A. Shamirian, C. E. Rowland, H. Shen, A. Das, R. D. Schaller, and P. T. Snee, “Bright type II quantum dots,” Chem. Mater. 27, 7276–7281 (2015).

Samokhvalov, P. S.

K. V. Vokhmintcev, P. S. Samokhvalov, and I. Nabiev, “Charge transfer and separation in photoexcited quantum dot-based systems,” Nano Today 11, 189–211 (2016).

Schaller, R. D.

C. M. Tyrakowski, A. Shamirian, C. E. Rowland, H. Shen, A. Das, R. D. Schaller, and P. T. Snee, “Bright type II quantum dots,” Chem. Mater. 27, 7276–7281 (2015).

Scher, E.

X. Peng, L. Manna, W. Yang, J. Wickham, E. Scher, A. Kadavanich, and A. P. Alivisatos, “Shape control of CdSe nanocrystals,” Nature 404(6773), 59–61 (2000).
[PubMed]

Schins, J. M.

W. H. Evers, J. M. Schins, M. Aerts, A. Kulkarni, P. Capiod, M. Berthe, B. Grandidier, C. Delerue, H. S. J. van der Zant, C. van Overbeek, J. L. Peters, D. Vanmaekelbergh, and L. D. A. Siebbeles, “High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds,” Nat. Commun. 6, 8195 (2015).
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Shamirian, A.

C. M. Tyrakowski, A. Shamirian, C. E. Rowland, H. Shen, A. Das, R. D. Schaller, and P. T. Snee, “Bright type II quantum dots,” Chem. Mater. 27, 7276–7281 (2015).

Shao, L.

X. Jin, W. Sun, S. Luo, L. Shao, J. Zhang, X. Luo, T. Wei, Y. Qin, Y. Song, and Q. Li, “Energy gradient architectured praseodymium chalcogenide quantum dot solar cells: towards unidirectionally funneling energy transfer,” J. Mater. Chem. A Mater. Energy Sustain. 3, 23876–23887 (2015).

Shen, H.

C. M. Tyrakowski, A. Shamirian, C. E. Rowland, H. Shen, A. Das, R. D. Schaller, and P. T. Snee, “Bright type II quantum dots,” Chem. Mater. 27, 7276–7281 (2015).

H. Shen, X. Bai, A. Wang, H. Wang, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “High-efficient deep-blue light-emitting diodes by using high quality ZnxCd1-xS/ZnS core/shell quantum dots,” Adv. Funct. Mater. 24, 2367–2373 (2014).

H. Shen, S. Wang, H. Wang, J. Niu, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “Highly efficient blue-green quantum dot light-emitting diodes using stable low-cadmium quaternary-alloy ZnCdSSe/ZnS core/shell nanocrystals,” ACS Appl. Mater. Interfaces 5(10), 4260–4265 (2013).
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Y. Shirasaki, G. J. Supran, M. G. Bawendi, and V. Bulovic, “Emergence of colloidal quantum-dot light-emitting technologies,” Nat. Photonics 7, 13–23 (2013).

Siebbeles, L. D. A.

W. H. Evers, J. M. Schins, M. Aerts, A. Kulkarni, P. Capiod, M. Berthe, B. Grandidier, C. Delerue, H. S. J. van der Zant, C. van Overbeek, J. L. Peters, D. Vanmaekelbergh, and L. D. A. Siebbeles, “High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds,” Nat. Commun. 6, 8195 (2015).
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C. M. Tyrakowski, A. Shamirian, C. E. Rowland, H. Shen, A. Das, R. D. Schaller, and P. T. Snee, “Bright type II quantum dots,” Chem. Mater. 27, 7276–7281 (2015).

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K.-H. Lee, J.-H. Lee, W.-S. Song, H. Ko, C. Lee, J.-H. Lee, and H. Yang, “Highly efficient, color-pure, color-stable blue quantum dot light-emitting devices,” ACS Nano 7(8), 7295–7302 (2013).
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X. Jin, W. Sun, S. Luo, L. Shao, J. Zhang, X. Luo, T. Wei, Y. Qin, Y. Song, and Q. Li, “Energy gradient architectured praseodymium chalcogenide quantum dot solar cells: towards unidirectionally funneling energy transfer,” J. Mater. Chem. A Mater. Energy Sustain. 3, 23876–23887 (2015).

Spinicelli, P.

B. Mahler, P. Spinicelli, S. Buil, X. Quelin, J.-P. Hermier, and B. Dubertret, “Towards non-blinking colloidal quantum dots,” Nat. Mater. 7(8), 659–664 (2008).
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W. Sukkabot, “Atomistic tight-binding computations of excitonic fine structure splitting in CdSe/ZnSe type-I and ZnSe/CdSe invert type-I core/shell nanocrystals,” Mater. Sci. Semicond. Process. 47, 57–61 (2016).

Sun, W.

Q. Li, X. Jin, X. Yang, C. Chen, Z. Chen, Y. Qin, T.-h. Wei, and W. Sun, “Reducing the excess energy offset in organic/inorganic hybrid solar cells: Toward faster electron transfer,” Appl. Catal. B 162, 524–531 (2015).

X. Jin, W. Sun, S. Luo, L. Shao, J. Zhang, X. Luo, T. Wei, Y. Qin, Y. Song, and Q. Li, “Energy gradient architectured praseodymium chalcogenide quantum dot solar cells: towards unidirectionally funneling energy transfer,” J. Mater. Chem. A Mater. Energy Sustain. 3, 23876–23887 (2015).

X. Jin, W. Sun, Z. Chen, T. Wei, C. Chen, X. He, Y. Yuan, Y. Li, and Q. Li, “Exciton generation/dissociation/charge-transfer enhancement in inorganic/organic hybrid solar cells by robust single nanocrystalline LnPxOy (Ln = Eu, Y) doping,” ACS Appl. Mater. Interfaces 6(11), 8771–8781 (2014).
[PubMed]

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Q. H. Li, X. Jin, Y. Yang, H. N. Wang, H. J. Xu, Y. Y. Cheng, T. H. Wei, Y. C. Qin, X. B. Luo, W. F. Sun, and S. L. Luo, “Nd2(S, Se, Te)3 colloidal quantum dots: synthesis, energy level alignment, charge transfer dynamics, and their applications to solar cells,” Adv. Funct. Mater. 26, 254–266 (2016).

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Y. Shirasaki, G. J. Supran, M. G. Bawendi, and V. Bulovic, “Emergence of colloidal quantum-dot light-emitting technologies,” Nat. Photonics 7, 13–23 (2013).

Titov, A.

H. Shen, X. Bai, A. Wang, H. Wang, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “High-efficient deep-blue light-emitting diodes by using high quality ZnxCd1-xS/ZnS core/shell quantum dots,” Adv. Funct. Mater. 24, 2367–2373 (2014).

H. Shen, S. Wang, H. Wang, J. Niu, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “Highly efficient blue-green quantum dot light-emitting diodes using stable low-cadmium quaternary-alloy ZnCdSSe/ZnS core/shell nanocrystals,” ACS Appl. Mater. Interfaces 5(10), 4260–4265 (2013).
[PubMed]

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C. M. Tyrakowski, A. Shamirian, C. E. Rowland, H. Shen, A. Das, R. D. Schaller, and P. T. Snee, “Bright type II quantum dots,” Chem. Mater. 27, 7276–7281 (2015).

van der Zant, H. S. J.

W. H. Evers, J. M. Schins, M. Aerts, A. Kulkarni, P. Capiod, M. Berthe, B. Grandidier, C. Delerue, H. S. J. van der Zant, C. van Overbeek, J. L. Peters, D. Vanmaekelbergh, and L. D. A. Siebbeles, “High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds,” Nat. Commun. 6, 8195 (2015).
[PubMed]

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W. H. Evers, J. M. Schins, M. Aerts, A. Kulkarni, P. Capiod, M. Berthe, B. Grandidier, C. Delerue, H. S. J. van der Zant, C. van Overbeek, J. L. Peters, D. Vanmaekelbergh, and L. D. A. Siebbeles, “High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds,” Nat. Commun. 6, 8195 (2015).
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E. Groeneveld, L. Witteman, M. Lefferts, X. Ke, S. Bals, G. Van Tendeloo, and Cde. M. Donega, “Tailoring ZnSe-CdSe colloidal quantum dots via cation exchange: from core/shell to alloy nanocrystals,” ACS Nano 7(9), 7913–7930 (2013).
[PubMed]

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W. H. Evers, J. M. Schins, M. Aerts, A. Kulkarni, P. Capiod, M. Berthe, B. Grandidier, C. Delerue, H. S. J. van der Zant, C. van Overbeek, J. L. Peters, D. Vanmaekelbergh, and L. D. A. Siebbeles, “High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds,” Nat. Commun. 6, 8195 (2015).
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K. V. Vokhmintcev, P. S. Samokhvalov, and I. Nabiev, “Charge transfer and separation in photoexcited quantum dot-based systems,” Nano Today 11, 189–211 (2016).

Wang, A.

H. Shen, X. Bai, A. Wang, H. Wang, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “High-efficient deep-blue light-emitting diodes by using high quality ZnxCd1-xS/ZnS core/shell quantum dots,” Adv. Funct. Mater. 24, 2367–2373 (2014).

Wang, H.

H. Shen, X. Bai, A. Wang, H. Wang, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “High-efficient deep-blue light-emitting diodes by using high quality ZnxCd1-xS/ZnS core/shell quantum dots,” Adv. Funct. Mater. 24, 2367–2373 (2014).

H. Shen, S. Wang, H. Wang, J. Niu, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “Highly efficient blue-green quantum dot light-emitting diodes using stable low-cadmium quaternary-alloy ZnCdSSe/ZnS core/shell nanocrystals,” ACS Appl. Mater. Interfaces 5(10), 4260–4265 (2013).
[PubMed]

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Q. H. Li, X. Jin, Y. Yang, H. N. Wang, H. J. Xu, Y. Y. Cheng, T. H. Wei, Y. C. Qin, X. B. Luo, W. F. Sun, and S. L. Luo, “Nd2(S, Se, Te)3 colloidal quantum dots: synthesis, energy level alignment, charge transfer dynamics, and their applications to solar cells,” Adv. Funct. Mater. 26, 254–266 (2016).

Wang, J.

X. Dai, Z. Zhang, Y. Jin, Y. Niu, H. Cao, X. Liang, L. Chen, J. Wang, and X. Peng, “Solution-processed, high-performance light-emitting diodes based on quantum dots,” Nature 515(7525), 96–99 (2014).
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Q. Li, H. Meng, P. Zhou, Y. Zheng, J. Wang, J. Yu, and J. Gong, “Zn1–xCdxS solid solutions with controlled bandgap and enhanced visible-light photocatalytic H2-production activity,” ACS Catal. 3, 882–889 (2013).

Wang, S.

H. Shen, S. Wang, H. Wang, J. Niu, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “Highly efficient blue-green quantum dot light-emitting diodes using stable low-cadmium quaternary-alloy ZnCdSSe/ZnS core/shell nanocrystals,” ACS Appl. Mater. Interfaces 5(10), 4260–4265 (2013).
[PubMed]

Wang, Y. A.

J. J. Li, Y. A. Wang, W. Guo, J. C. Keay, T. D. Mishima, M. B. Johnson, and X. Peng, “Large-scale synthesis of nearly monodisperse CdSe/CdS core/shell nanocrystals using air-stable reagents via successive ion layer adsorption and reaction,” J. Am. Chem. Soc. 125(41), 12567–12575 (2003).
[PubMed]

Wei, H.

O. Chen, J. Zhao, V. P. Chauhan, J. Cui, C. Wong, D. K. Harris, H. Wei, H.-S. Han, D. Fukumura, R. K. Jain, and M. G. Bawendi, “Compact high-quality CdSe-CdS core-shell nanocrystals with narrow emission linewidths and suppressed blinking,” Nat. Mater. 12(5), 445–451 (2013).
[PubMed]

Wei, T.

X. Jin, W. Sun, S. Luo, L. Shao, J. Zhang, X. Luo, T. Wei, Y. Qin, Y. Song, and Q. Li, “Energy gradient architectured praseodymium chalcogenide quantum dot solar cells: towards unidirectionally funneling energy transfer,” J. Mater. Chem. A Mater. Energy Sustain. 3, 23876–23887 (2015).

X. Jin, W. Sun, Z. Chen, T. Wei, C. Chen, X. He, Y. Yuan, Y. Li, and Q. Li, “Exciton generation/dissociation/charge-transfer enhancement in inorganic/organic hybrid solar cells by robust single nanocrystalline LnPxOy (Ln = Eu, Y) doping,” ACS Appl. Mater. Interfaces 6(11), 8771–8781 (2014).
[PubMed]

Wei, T. H.

Q. H. Li, X. Jin, Y. Yang, H. N. Wang, H. J. Xu, Y. Y. Cheng, T. H. Wei, Y. C. Qin, X. B. Luo, W. F. Sun, and S. L. Luo, “Nd2(S, Se, Te)3 colloidal quantum dots: synthesis, energy level alignment, charge transfer dynamics, and their applications to solar cells,” Adv. Funct. Mater. 26, 254–266 (2016).

Wei, T.-h.

Q. Li, X. Jin, X. Yang, C. Chen, Z. Chen, Y. Qin, T.-h. Wei, and W. Sun, “Reducing the excess energy offset in organic/inorganic hybrid solar cells: Toward faster electron transfer,” Appl. Catal. B 162, 524–531 (2015).

Wickham, J.

X. Peng, L. Manna, W. Yang, J. Wickham, E. Scher, A. Kadavanich, and A. P. Alivisatos, “Shape control of CdSe nanocrystals,” Nature 404(6773), 59–61 (2000).
[PubMed]

Witteman, L.

E. Groeneveld, L. Witteman, M. Lefferts, X. Ke, S. Bals, G. Van Tendeloo, and Cde. M. Donega, “Tailoring ZnSe-CdSe colloidal quantum dots via cation exchange: from core/shell to alloy nanocrystals,” ACS Nano 7(9), 7913–7930 (2013).
[PubMed]

Wong, C.

O. Chen, J. Zhao, V. P. Chauhan, J. Cui, C. Wong, D. K. Harris, H. Wei, H.-S. Han, D. Fukumura, R. K. Jain, and M. G. Bawendi, “Compact high-quality CdSe-CdS core-shell nanocrystals with narrow emission linewidths and suppressed blinking,” Nat. Mater. 12(5), 445–451 (2013).
[PubMed]

Woo, H.

J. Kwak, W. K. Bae, D. Lee, I. Park, J. Lim, M. Park, H. Cho, H. Woo, D. Y. Yoon, K. Char, S. Lee, and C. Lee, “Bright and efficient full-color colloidal quantum dot light-emitting diodes using an inverted device structure,” Nano Lett. 12(5), 2362–2366 (2012).
[PubMed]

Wood, V.

V. Wood, M. J. Panzer, J. M. Caruge, J. E. Halpert, M. G. Bawendi, and V. Bulović, “Air-stable operation of transparent, colloidal quantum dot based LEDs with a unipolar device architecture,” Nano Lett. 10(1), 24–29 (2010).
[PubMed]

Xie, R.

X. Zhong, R. Xie, Y. Zhang, T. Basché, and W. Knoll, “High-quality violet- to red-emitting ZnSe/CdSe core/shell nanocrystals,” Chem. Mater. 17, 4038–4042 (2005).

Xu, H. J.

Q. H. Li, X. Jin, Y. Yang, H. N. Wang, H. J. Xu, Y. Y. Cheng, T. H. Wei, Y. C. Qin, X. B. Luo, W. F. Sun, and S. L. Luo, “Nd2(S, Se, Te)3 colloidal quantum dots: synthesis, energy level alignment, charge transfer dynamics, and their applications to solar cells,” Adv. Funct. Mater. 26, 254–266 (2016).

Yang, H.

K.-H. Lee, J.-H. Lee, W.-S. Song, H. Ko, C. Lee, J.-H. Lee, and H. Yang, “Highly efficient, color-pure, color-stable blue quantum dot light-emitting devices,” ACS Nano 7(8), 7295–7302 (2013).
[PubMed]

Yang, P.

P. Yang, M. Ando, and N. Murase, “Highly luminescent CdSe/CdxZn1-xS quantum dots coated with thickness-controlled SiO2 shell through silanization,” Langmuir 27(15), 9535–9540 (2011).
[PubMed]

Yang, W.

X. Peng, L. Manna, W. Yang, J. Wickham, E. Scher, A. Kadavanich, and A. P. Alivisatos, “Shape control of CdSe nanocrystals,” Nature 404(6773), 59–61 (2000).
[PubMed]

Yang, X.

Q. Li, X. Jin, X. Yang, C. Chen, Z. Chen, Y. Qin, T.-h. Wei, and W. Sun, “Reducing the excess energy offset in organic/inorganic hybrid solar cells: Toward faster electron transfer,” Appl. Catal. B 162, 524–531 (2015).

Yang, Y.

Q. H. Li, X. Jin, Y. Yang, H. N. Wang, H. J. Xu, Y. Y. Cheng, T. H. Wei, Y. C. Qin, X. B. Luo, W. F. Sun, and S. L. Luo, “Nd2(S, Se, Te)3 colloidal quantum dots: synthesis, energy level alignment, charge transfer dynamics, and their applications to solar cells,” Adv. Funct. Mater. 26, 254–266 (2016).

H. Shen, X. Bai, A. Wang, H. Wang, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “High-efficient deep-blue light-emitting diodes by using high quality ZnxCd1-xS/ZnS core/shell quantum dots,” Adv. Funct. Mater. 24, 2367–2373 (2014).

H. Shen, S. Wang, H. Wang, J. Niu, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “Highly efficient blue-green quantum dot light-emitting diodes using stable low-cadmium quaternary-alloy ZnCdSSe/ZnS core/shell nanocrystals,” ACS Appl. Mater. Interfaces 5(10), 4260–4265 (2013).
[PubMed]

W. Nan, Y. Niu, H. Qin, F. Cui, Y. Yang, R. Lai, W. Lin, and X. Peng, “Crystal structure control of zinc-blende CdSe/CdS core/shell nanocrystals: synthesis and structure-dependent optical properties,” J. Am. Chem. Soc. 134(48), 19685–19693 (2012).
[PubMed]

Yoon, D. Y.

J. Kwak, W. K. Bae, D. Lee, I. Park, J. Lim, M. Park, H. Cho, H. Woo, D. Y. Yoon, K. Char, S. Lee, and C. Lee, “Bright and efficient full-color colloidal quantum dot light-emitting diodes using an inverted device structure,” Nano Lett. 12(5), 2362–2366 (2012).
[PubMed]

Yu, J.

Q. Li, H. Meng, P. Zhou, Y. Zheng, J. Wang, J. Yu, and J. Gong, “Zn1–xCdxS solid solutions with controlled bandgap and enhanced visible-light photocatalytic H2-production activity,” ACS Catal. 3, 882–889 (2013).

Yuan, Y.

X. Jin, W. Sun, Z. Chen, T. Wei, C. Chen, X. He, Y. Yuan, Y. Li, and Q. Li, “Exciton generation/dissociation/charge-transfer enhancement in inorganic/organic hybrid solar cells by robust single nanocrystalline LnPxOy (Ln = Eu, Y) doping,” ACS Appl. Mater. Interfaces 6(11), 8771–8781 (2014).
[PubMed]

Zhang, H.

Z. Pan, H. Zhang, K. Cheng, Y. Hou, J. Hua, and X. Zhong, “Highly efficient inverted type-I CdS/CdSe core/shell structure QD-sensitized solar cells,” ACS Nano 6(5), 3982–3991 (2012).
[PubMed]

F. Du, H. Zhang, X. Du, J. Zhu, and X. Zhong, “Controllable synthesis and optical properties of CdS/CdSe hetero-nanostructures with various dimensionalities,” Mater. Chem. Phys. 121, 118–124 (2010).

Zhang, J.

X. Jin, W. Sun, S. Luo, L. Shao, J. Zhang, X. Luo, T. Wei, Y. Qin, Y. Song, and Q. Li, “Energy gradient architectured praseodymium chalcogenide quantum dot solar cells: towards unidirectionally funneling energy transfer,” J. Mater. Chem. A Mater. Energy Sustain. 3, 23876–23887 (2015).

Zhang, Y.

X. Zhong, R. Xie, Y. Zhang, T. Basché, and W. Knoll, “High-quality violet- to red-emitting ZnSe/CdSe core/shell nanocrystals,” Chem. Mater. 17, 4038–4042 (2005).

Zhang, Z.

X. Dai, Z. Zhang, Y. Jin, Y. Niu, H. Cao, X. Liang, L. Chen, J. Wang, and X. Peng, “Solution-processed, high-performance light-emitting diodes based on quantum dots,” Nature 515(7525), 96–99 (2014).
[PubMed]

Zhao, J.

O. Chen, J. Zhao, V. P. Chauhan, J. Cui, C. Wong, D. K. Harris, H. Wei, H.-S. Han, D. Fukumura, R. K. Jain, and M. G. Bawendi, “Compact high-quality CdSe-CdS core-shell nanocrystals with narrow emission linewidths and suppressed blinking,” Nat. Mater. 12(5), 445–451 (2013).
[PubMed]

Zheng, Y.

H. Shen, X. Bai, A. Wang, H. Wang, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “High-efficient deep-blue light-emitting diodes by using high quality ZnxCd1-xS/ZnS core/shell quantum dots,” Adv. Funct. Mater. 24, 2367–2373 (2014).

H. Shen, S. Wang, H. Wang, J. Niu, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “Highly efficient blue-green quantum dot light-emitting diodes using stable low-cadmium quaternary-alloy ZnCdSSe/ZnS core/shell nanocrystals,” ACS Appl. Mater. Interfaces 5(10), 4260–4265 (2013).
[PubMed]

Q. Li, H. Meng, P. Zhou, Y. Zheng, J. Wang, J. Yu, and J. Gong, “Zn1–xCdxS solid solutions with controlled bandgap and enhanced visible-light photocatalytic H2-production activity,” ACS Catal. 3, 882–889 (2013).

Zhong, X.

Z. Pan, H. Zhang, K. Cheng, Y. Hou, J. Hua, and X. Zhong, “Highly efficient inverted type-I CdS/CdSe core/shell structure QD-sensitized solar cells,” ACS Nano 6(5), 3982–3991 (2012).
[PubMed]

F. Du, H. Zhang, X. Du, J. Zhu, and X. Zhong, “Controllable synthesis and optical properties of CdS/CdSe hetero-nanostructures with various dimensionalities,” Mater. Chem. Phys. 121, 118–124 (2010).

X. Zhong, R. Xie, Y. Zhang, T. Basché, and W. Knoll, “High-quality violet- to red-emitting ZnSe/CdSe core/shell nanocrystals,” Chem. Mater. 17, 4038–4042 (2005).

Zhou, P.

Q. Li, H. Meng, P. Zhou, Y. Zheng, J. Wang, J. Yu, and J. Gong, “Zn1–xCdxS solid solutions with controlled bandgap and enhanced visible-light photocatalytic H2-production activity,” ACS Catal. 3, 882–889 (2013).

Zhu, J.

F. Du, H. Zhang, X. Du, J. Zhu, and X. Zhong, “Controllable synthesis and optical properties of CdS/CdSe hetero-nanostructures with various dimensionalities,” Mater. Chem. Phys. 121, 118–124 (2010).

ACS Appl. Mater. Interfaces (2)

X. Jin, W. Sun, Z. Chen, T. Wei, C. Chen, X. He, Y. Yuan, Y. Li, and Q. Li, “Exciton generation/dissociation/charge-transfer enhancement in inorganic/organic hybrid solar cells by robust single nanocrystalline LnPxOy (Ln = Eu, Y) doping,” ACS Appl. Mater. Interfaces 6(11), 8771–8781 (2014).
[PubMed]

H. Shen, S. Wang, H. Wang, J. Niu, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “Highly efficient blue-green quantum dot light-emitting diodes using stable low-cadmium quaternary-alloy ZnCdSSe/ZnS core/shell nanocrystals,” ACS Appl. Mater. Interfaces 5(10), 4260–4265 (2013).
[PubMed]

ACS Catal. (1)

Q. Li, H. Meng, P. Zhou, Y. Zheng, J. Wang, J. Yu, and J. Gong, “Zn1–xCdxS solid solutions with controlled bandgap and enhanced visible-light photocatalytic H2-production activity,” ACS Catal. 3, 882–889 (2013).

ACS Nano (4)

K.-H. Lee, J.-H. Lee, W.-S. Song, H. Ko, C. Lee, J.-H. Lee, and H. Yang, “Highly efficient, color-pure, color-stable blue quantum dot light-emitting devices,” ACS Nano 7(8), 7295–7302 (2013).
[PubMed]

E. Groeneveld, L. Witteman, M. Lefferts, X. Ke, S. Bals, G. Van Tendeloo, and Cde. M. Donega, “Tailoring ZnSe-CdSe colloidal quantum dots via cation exchange: from core/shell to alloy nanocrystals,” ACS Nano 7(9), 7913–7930 (2013).
[PubMed]

B. G. Jeong, Y.-S. Park, J. H. Chang, I. Cho, J. K. Kim, H. Kim, K. Char, J. Cho, V. I. Klimov, P. Park, D. C. Lee, and W. K. Bae, “Colloidal spherical quantum wells with near-unity photoluminescence quantum yield and suppressed blinking,” ACS Nano 10, 9297–9305 (2016).
[PubMed]

Z. Pan, H. Zhang, K. Cheng, Y. Hou, J. Hua, and X. Zhong, “Highly efficient inverted type-I CdS/CdSe core/shell structure QD-sensitized solar cells,” ACS Nano 6(5), 3982–3991 (2012).
[PubMed]

Adv. Funct. Mater. (2)

Q. H. Li, X. Jin, Y. Yang, H. N. Wang, H. J. Xu, Y. Y. Cheng, T. H. Wei, Y. C. Qin, X. B. Luo, W. F. Sun, and S. L. Luo, “Nd2(S, Se, Te)3 colloidal quantum dots: synthesis, energy level alignment, charge transfer dynamics, and their applications to solar cells,” Adv. Funct. Mater. 26, 254–266 (2016).

H. Shen, X. Bai, A. Wang, H. Wang, L. Qian, Y. Yang, A. Titov, J. Hyvonen, Y. Zheng, and L. S. Li, “High-efficient deep-blue light-emitting diodes by using high quality ZnxCd1-xS/ZnS core/shell quantum dots,” Adv. Funct. Mater. 24, 2367–2373 (2014).

Appl. Catal. B (1)

Q. Li, X. Jin, X. Yang, C. Chen, Z. Chen, Y. Qin, T.-h. Wei, and W. Sun, “Reducing the excess energy offset in organic/inorganic hybrid solar cells: Toward faster electron transfer,” Appl. Catal. B 162, 524–531 (2015).

Chem. Mater. (3)

X. Zhong, R. Xie, Y. Zhang, T. Basché, and W. Knoll, “High-quality violet- to red-emitting ZnSe/CdSe core/shell nanocrystals,” Chem. Mater. 17, 4038–4042 (2005).

C. M. Tyrakowski, A. Shamirian, C. E. Rowland, H. Shen, A. Das, R. D. Schaller, and P. T. Snee, “Bright type II quantum dots,” Chem. Mater. 27, 7276–7281 (2015).

W. K. Bae, M. K. Nam, K. Char, and S. Lee, “Gram-scale one-pot synthesis of highly luminescent blue emitting Cd1−xZnxS/ZnS nanocrystals,” Chem. Mater. 20, 5307–5313 (2008).

Chem. Rev. (1)

C. Burda, X. Chen, R. Narayanan, and M. A. El-Sayed, “Chemistry and properties of nanocrystals of different shapes,” Chem. Rev. 105(4), 1025–1102 (2005).
[PubMed]

J. Am. Chem. Soc. (3)

J. J. Li, Y. A. Wang, W. Guo, J. C. Keay, T. D. Mishima, M. B. Johnson, and X. Peng, “Large-scale synthesis of nearly monodisperse CdSe/CdS core/shell nanocrystals using air-stable reagents via successive ion layer adsorption and reaction,” J. Am. Chem. Soc. 125(41), 12567–12575 (2003).
[PubMed]

H. Qin, Y. Niu, R. Meng, X. Lin, R. Lai, W. Fang, and X. Peng, “Single-dot spectroscopy of zinc-blende CdSe/CdS core/shell nanocrystals: nonblinking and correlation with ensemble measurements,” J. Am. Chem. Soc. 136(1), 179–187 (2014).
[PubMed]

W. Nan, Y. Niu, H. Qin, F. Cui, Y. Yang, R. Lai, W. Lin, and X. Peng, “Crystal structure control of zinc-blende CdSe/CdS core/shell nanocrystals: synthesis and structure-dependent optical properties,” J. Am. Chem. Soc. 134(48), 19685–19693 (2012).
[PubMed]

J. Electron. Mater. (1)

H. Kumar, P. B. Barman, and R. R. Singh, “Low-Temperature growth of inverted hexagonal ZnS/CdS quantum dots: functional and luminescence properties,” J. Electron. Mater. 44, 675–681 (2014).

J. Mater. Chem. A Mater. Energy Sustain. (1)

X. Jin, W. Sun, S. Luo, L. Shao, J. Zhang, X. Luo, T. Wei, Y. Qin, Y. Song, and Q. Li, “Energy gradient architectured praseodymium chalcogenide quantum dot solar cells: towards unidirectionally funneling energy transfer,” J. Mater. Chem. A Mater. Energy Sustain. 3, 23876–23887 (2015).

J. Phys. Chem. C (2)

P. Maity, T. Debnath, and H. N. Ghosh, “Ultrafast charge carrier delocalization in CdSe/CdS quasi-type II and CdS/CdSe inverted type I core–shell: a structural analysis through carrier-quenching study,” J. Phys. Chem. C 119, 26202–26211 (2015).

P. Maity, T. Debnath, T. Banerjee, A. Das, and H. N. Ghosh, “Charge delocalization in the cascade band structure CdS/CdSe and CdS/CdTe core–shell sensitized with Re(I)–polypyridyl complex,” J. Phys. Chem. C 120, 10051–10061 (2016).

Langmuir (1)

P. Yang, M. Ando, and N. Murase, “Highly luminescent CdSe/CdxZn1-xS quantum dots coated with thickness-controlled SiO2 shell through silanization,” Langmuir 27(15), 9535–9540 (2011).
[PubMed]

Mater. Chem. Phys. (1)

F. Du, H. Zhang, X. Du, J. Zhu, and X. Zhong, “Controllable synthesis and optical properties of CdS/CdSe hetero-nanostructures with various dimensionalities,” Mater. Chem. Phys. 121, 118–124 (2010).

Mater. Sci. Semicond. Process. (1)

W. Sukkabot, “Atomistic tight-binding computations of excitonic fine structure splitting in CdSe/ZnSe type-I and ZnSe/CdSe invert type-I core/shell nanocrystals,” Mater. Sci. Semicond. Process. 47, 57–61 (2016).

Nano Lett. (3)

J. Kwak, W. K. Bae, D. Lee, I. Park, J. Lim, M. Park, H. Cho, H. Woo, D. Y. Yoon, K. Char, S. Lee, and C. Lee, “Bright and efficient full-color colloidal quantum dot light-emitting diodes using an inverted device structure,” Nano Lett. 12(5), 2362–2366 (2012).
[PubMed]

V. Wood, M. J. Panzer, J. M. Caruge, J. E. Halpert, M. G. Bawendi, and V. Bulović, “Air-stable operation of transparent, colloidal quantum dot based LEDs with a unipolar device architecture,” Nano Lett. 10(1), 24–29 (2010).
[PubMed]

J. Kwak, J. Lim, M. Park, S. Lee, K. Char, and C. Lee, “High-power genuine ultraviolet light-emitting diodes based on colloidal nanocrystal quantum dots,” Nano Lett. 15(6), 3793–3799 (2015).
[PubMed]

Nano Res. (1)

Y. Niu, C. Pu, R. Lai, R. Meng, W. Lin, H. Qin, and X. Peng, “One-pot/three-step synthesis of zinc-blende CdSe/CdS core/shell nanocrystals with thick shells,” Nano Res. 10, 1149–1162 (2017).

Nano Today (1)

K. V. Vokhmintcev, P. S. Samokhvalov, and I. Nabiev, “Charge transfer and separation in photoexcited quantum dot-based systems,” Nano Today 11, 189–211 (2016).

Nat. Commun. (1)

W. H. Evers, J. M. Schins, M. Aerts, A. Kulkarni, P. Capiod, M. Berthe, B. Grandidier, C. Delerue, H. S. J. van der Zant, C. van Overbeek, J. L. Peters, D. Vanmaekelbergh, and L. D. A. Siebbeles, “High charge mobility in two-dimensional percolative networks of PbSe quantum dots connected by atomic bonds,” Nat. Commun. 6, 8195 (2015).
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Nat. Mater. (2)

B. Mahler, P. Spinicelli, S. Buil, X. Quelin, J.-P. Hermier, and B. Dubertret, “Towards non-blinking colloidal quantum dots,” Nat. Mater. 7(8), 659–664 (2008).
[PubMed]

O. Chen, J. Zhao, V. P. Chauhan, J. Cui, C. Wong, D. K. Harris, H. Wei, H.-S. Han, D. Fukumura, R. K. Jain, and M. G. Bawendi, “Compact high-quality CdSe-CdS core-shell nanocrystals with narrow emission linewidths and suppressed blinking,” Nat. Mater. 12(5), 445–451 (2013).
[PubMed]

Nat. Photonics (2)

Y. Shirasaki, G. J. Supran, M. G. Bawendi, and V. Bulovic, “Emergence of colloidal quantum-dot light-emitting technologies,” Nat. Photonics 7, 13–23 (2013).

K.-S. Cho, E. K. Lee, W.-J. Joo, E. Jang, T.-H. Kim, S. J. Lee, S.-J. Kwon, J. Y. Han, B.-K. Kim, B. L. Choi, and J. M. Kim, “High-performance crosslinked colloidal quantum-dot light-emitting diodes,” Nat. Photonics 3, 341–345 (2009).

Nature (3)

J. Bao and M. G. Bawendi, “A colloidal quantum dot spectrometer,” Nature 523(7558), 67–70 (2015).
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X. Dai, Z. Zhang, Y. Jin, Y. Niu, H. Cao, X. Liang, L. Chen, J. Wang, and X. Peng, “Solution-processed, high-performance light-emitting diodes based on quantum dots,” Nature 515(7525), 96–99 (2014).
[PubMed]

X. Peng, L. Manna, W. Yang, J. Wickham, E. Scher, A. Kadavanich, and A. P. Alivisatos, “Shape control of CdSe nanocrystals,” Nature 404(6773), 59–61 (2000).
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Phys. Rev. B (1)

D. Canneson, L. Biadala, S. Buil, X. Quélin, C. Javaux, B. Dubertret, and J. P. Hermier, “Blinking suppression and biexcitonic emission in thick-shell CdSe/CdS nanocrystals at cryogenic temperature,” Phys. Rev. B 89, 035303 (2014).

Science (1)

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Figures (8)

Fig. 1
Fig. 1 XRD patterns of the pure Cd0.1Zn0.9S with a diameter of 4.5 nm, Cd0.1Zn0.9S/CdSe core/shell nanocrystals with CdSe shell thickness of 2 ML and 4 ML. The line XRD spectra correspond to bulk wurtzite Cd0.1Zn0.9S (bottom) and bulk zinc blende CdSe (top), respectively.
Fig. 2
Fig. 2 (a) TEM image of Cd0.1Zn0.9S; (b) High resolution TEM image of Cd0.1Zn0.9S; (c) TEM image of Cd0.1Zn0.9S/CdSe with two monlayer (2 ML) CdSe shell; (d) High resolution TEM image of Cd0.1Zn0.9S/CdSe. Insets highlight the size distributions.
Fig. 3
Fig. 3 (a) Digital photographs of Cd0.1Zn0.9S/CdSe QD solutions with different CdSe shell thickness under the irradiation of a UV lamp. The absorption (b) and PL (c) spectra of the QDs.
Fig. 4
Fig. 4 Time-resolved PL decays of the Cd0.1Zn0.9S/CdSe core/shell QDs with 1 ML, 2 ML, 3 ML and 4 ML CdSe shell in n-hexane, excited at λ = 573, 602, 632 and 653 nm, respectively.
Fig. 5
Fig. 5 The current density versus driving voltage of the electron-only (a) and the hole-only (b) devices.
Fig. 6
Fig. 6 (a) Schematic of the device structure; (b) Cross-sectional TEM image of a typical device.
Fig. 7
Fig. 7 PL and EL spectra of the Cd0.1Zn0.9S/CdSe (a) and CdSe/Cd0.1Zn0.9S (b) based LED; Evolution of EL spectra with driving voltages of the Cd0.1Zn0.9S/CdSe (c) and CdSe/Cd0.1Zn0.9S (d) based devices.
Fig. 8
Fig. 8 Current density, luminance of the Cd0.1Zn0.9S/CdSe (a), CdSe/Cd0.1Zn0.9S (b) based devices; (c) EQEs of the two devices.

Tables (2)

Tables Icon

Table 1 Optical parameters of the QDs.

Tables Icon

Table 2 Kinetic parameters of the QDs obtained from time-resolved PL decays.

Equations (2)

Equations on this page are rendered with MathJax. Learn more.

I ( t ) = [ a 1 exp ( - t / τ 1 ) + a 2 exp ( - t / τ 2 ) ] F ( t )
τ = a 1 τ 1 2 + a 2 τ 2 2 a 1 τ 1 + a 2 τ 2

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