Efficiency enhancement of ultrathin CIGS solar cells by optimal bandgap grading

Faiz Ahmad; Tom H. Anderson; Peter B. Monk; Akhlesh Lakhtakia

doi:10.1364/AO.58.006067

Applied Optics
Vol. 58,
Issue 22,
pp. 6067-6078
(2019)
•https://doi.org/10.1364/AO.58.006067

Efficiency enhancement of ultrathin CIGS solar cells by optimal bandgap grading

Faiz Ahmad, Tom H. Anderson, Peter B. Monk, and Akhlesh Lakhtakia

Get PDF
Email
Share
Get Citation
Copy Citation Text
Faiz Ahmad, Tom H. Anderson, Peter B. Monk, and Akhlesh Lakhtakia, "Efficiency enhancement of ultrathin CIGS solar cells by optimal bandgap grading," Appl. Opt. 58, 6067-6078 (2019)

Export Citation
- BibTex
- Endnote (RIS)
- HTML
- Plain Text
Citation alert
Save article
Editors' Pick

Check for updates

Related Topics
Table of Contents Category
- Optical Devices, Sensors, and Detectors
Optics & Photonics Topics
?

The topics in this list come from the Optics and Photonics Topics applied to this article.

About this Article
History
- Original Manuscript: April 19, 2019
- Revised Manuscript: June 25, 2019
- Manuscript Accepted: June 27, 2019
- Published: July 26, 2019

Accepted Manuscript
Download Accepted Manuscript
Access to this article is made available via and is subject to OSA Publishing Terms of Use.

Abstract

The power conversion efficiency of an ultrathin ${CuIn}_{1 - ξ} {Ga}_{ξ} {Se}_{2}$ (CIGS) solar cell was maximized using a coupled optoelectronic model to determine the optimal bandgap grading of the nonhomogeneous CIGS layer in the thickness direction. The bandgap of the CIGS layer was either sinusoidally or linearly graded, and the solar cell was modeled to have a metallic backreflector corrugated periodically along a fixed direction in the plane. The model predicts that specially tailored bandgap grading can significantly improve the efficiency, with much smaller improvements due to the periodic corrugations. An efficiency of 27.7% with the conventional 2200-nm-thick CIGS layer is predicted with sinusoidal bandgap grading, in comparison to 22% efficiency obtained experimentally with homogeneous bandgap. Furthermore, the inclusion of sinusoidal grading increases the predicted efficiency to 22.89% with just a 600-nm-thick CIGS layer. These high efficiencies arise due to a large electron–hole pair generation rate in the narrow-bandgap regions and the elevation of the open-circuit voltage due to a wider bandgap in the region toward the front surface of the CIGS layer. Thus, bandgap nonhomogeneity, in conjunction with periodic corrugation of the backreflector, can be effective in realizing ultrathin CIGS solar cells that can help overcome the scarcity of indium.

Full Article | PDF Article

Corrections

Faiz Ahmad, Tom H. Anderson, Peter B. Monk, and Akhlesh Lakhtakia, "Efficiency enhancement of ultrathin CIGS solar cells by optimal bandgap grading: erratum," Appl. Opt. 59, 2615-2615 (2020)
https://opg.optica.org/ao/abstract.cfm?uri=ao-59-8-2615

More Like This

Efficiency enhancement of ultrathin CIGS solar cells by optimal bandgap grading. Part II: finite-difference algorithm and double-layer antireflection coatings

Faiz Ahmad, Benjamin J. Civiletti, Peter B. Monk, and Akhlesh Lakhtakia
Appl. Opt. 61(33) 10049-10061 (2022)

Efficiency enhancement of ultrathin CIGS solar cells by optimal bandgap grading. Part III: piecewise-homogeneous grading

Faiz Ahmad, Peter B. Monk, and Akhlesh Lakhtakia
Appl. Opt. 63(11) 2831-2836 (2024)

Optoelectronic optimization of graded-bandgap thin-film AlGaAs solar cells

Faiz Ahmad, Akhlesh Lakhtakia, and Peter B. Monk
Appl. Opt. 59(4) 1018-1027 (2020)

Previous Article Next Article

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Figures (10)

You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Tables (7)

You do not have subscription access to this journal. Article tables are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Equations (20)

You do not have subscription access to this journal. Equations are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access Optica Member Subscription

Parameter (Unit)	iZnO	CdS	CIGS
$E_{g}$ (eV)	3.3	2.4	0.947–1.626 (Ga-dependent)
$χ$ (eV)	4.4	4.2	4.5–3.9 (Ga-dependent)
$N_{c}$ ( ${cm}^{- 3}$ )	$3 \times 10^{18}$	$1.3 \times 10^{18}$	$6.8 \times 10^{17}$
$N_{v}$ ( ${cm}^{- 3}$ )	$1.7 \times 10^{19}$	$9.1 \times 10^{19}$	$1.5 \times 10^{19}$
$N_{D}$ ( ${cm}^{- 3}$ )	$1 \times 10^{17}$ (donor)	$5 \times 10^{17}$ (donor)	$2 \times 10^{16}$ (acceptor)
$μ_{n}$ ( ${cm}^{- 2} V^{- 1} s^{- 1}$ )	100	72	100
$μ_{p}$ ( ${cm}^{- 2} V^{- 1} s^{- 1}$ )	31	20	13
$ε_{dc}$	9	5.4	13.6
$N_{f}$ ( ${cm}^{- 3}$ )	$10^{16}$	$5 \times 10^{17}$	$10^{13} - 10^{16}$ (Ga-dependent)
$E_{T}$	Midgap	Midgap	Midgap
$σ_{n}$ ( ${cm}^{2}$ )	$5 \times 10^{- 13}$	$5 \times 10^{- 13}$	$5 \times 10^{- 13}$
$σ_{p}$ ( ${cm}^{2}$ )	$10^{- 15}$	$10^{- 15}$	$10^{- 15}$
$R_{B}$ ( ${cm}^{- 3} s^{- 1}$ )	$10^{- 10}$	$10^{- 10}$	$10^{- 10}$
$v_{th}$ ( ${cm s}^{- 1}$ )	$10^{7}$	$10^{7}$	$10^{7}$

$ξ$	$E_{g, \min}$ (eV)		$J_{sc}$ ( $mA {cm}^{- 2}$ )	$V_{oc}$ (mV)	$F F$ (%)	$η$ (%)
0	0.95	Model	38.63	497	78	15.05
		Experiment (Ref. [48])	40.58	491	66	14.5
		Experiment (Ref. [48])	41.1	491	75	15.0
0.25	1.12	Model	34.41	648	81	18.12
		Experiment (Ref. [48])	35.22	692	79	19.5
		Experiment (Ref. [1])	37.8	741	81	22.6
1	1.626	Model	14.86	911	73	9.92
		Experiment (Ref. [48])	14.88	823	71	9.53
		Experiment (Ref. [48])	18.61	905	75	10.2

$L_{a}$ (nm)	$E_{g, \min}$ (eV)	$J_{sc}$ ( $mA {cm}^{- 2}$ )	$V_{oc}$ (mV)	$F F$ (%)	$η$ (%)
0	1.27	21.63	705	77	11.88
50	1.27	22.65	711	77	12.49

$L_{CIGS}$ (nm)	$E_{g, \min}$ (eV)	$J_{sc}$ ( $mA {cm}^{- 2}$ )	$V_{oc}$ (mV)	$F F$ (%)	$η$ (%)
100	1.28	14.89	624	78	7.25
200	1.26	19.50	660	76	9.76
300	1.25	22.56	681	76	11.59
400	1.27	22.65	711	77	12.49
500	1.25	23.71	704	78	13.15
600	1.24	24.66	704	79	13.79
900	1.25	25.68	725	80	15.08
1200	1.28	25.72	756	81	15.90
2200	1.24	31.11	742	82	18.93

$L_{CIGS}$ (nm)	$E_{g, \min}$ (eV)	$L_{x}$ (nm)	$ζ$	$L_{g}$ (nm)	$J_{sc}$ ( $mA {cm}^{- 2}$ )	$V_{oc}$ (mV)	$F F$ (%)	$η$ (%)
100	1.28	500	0.50	97	14.89	624	78	7.25
200	1.26	510	0.50	101	19.53	661	76	9.91
300	1.25	510	0.50	101	22.56	681	76	11.59
400	1.27	510	0.49	101	22.79	711	77	12.58
500	1.25	510	0.48	106	23.78	705	78	13.19
600	1.24	510	0.48	105	24.69	704	79	13.81
900	1.25	502	0.49	101	25.71	725	80	15.09
1200	1.28	502	0.49	101	25.72	759	81	15.90
2200	1.24	502	0.49	101	31.11	742	82	18.93

$L_{CIGS}$ (nm)	$E_{g, \max}$ (eV)	$E_{g, \min}$ (eV)	A	$L_{x}$ (nm)	$ζ$	$L_{g}$ (nm)	$J_{sc}$ ( $mA {cm}^{- 2}$ )	$V_{oc}$ (mV)	$F F$	$η$
100	1.61	0.96	0.98	500	0.50	97	15.09	960	68	9.88
200	1.61	0.96	0.98	510	0.51	101	19.28	995	62	12.08
300	1.62	0.96	0.98	502	0.49	101	20.70	1010	63	13.34
400	1.62	0.96	0.98	510	0.49	101	21.13	1011	67	14.34
500	1.62	0.95	0.99	510	0.48	106	21.31	1017	69	15.14
600	1.62	0.95	0.75	500	0.50	101	21.48	1023	71	15.79
900	1.62	0.95	0.75	500	0.50	101	22.21	1032	75	17.24
1200	1.62	0.95	0.75	500	0.50	101	22.74	1037	76	18.07
2200	1.62	0.95	0.75	500	0.50	101	24.09	1039	77	19.27

$L_{CIGS}$ (nm)	$E_{g, \min}$ (eV)	A	$α$	$K$	$ψ$	$L_{x}$ (nm)	$ζ$	$L_{g}$ (nm)	$J_{sc}$ ( $mA {cm}^{- 2}$ )	$V_{oc}$ (mV)	$F F$ (%)	$η$ (%)
100	0.96	0.99	6.14	0.75	0.75	510	0.50	101	17.04	969	71	12.37
200	0.95	1.00	6	1.5	0.75	500	0.48	101	24.12	1007	69	16.89
300	0.95	0.98	6	1.5	0.74	502	0.49	101	25.98	1023	71	19.01
400	0.95	0.98	6	1.5	0.75	500	0.50	111	27.17	1033	73	20.66
500	0.95	0.99	6	1.5	0.76	520	0.50	111	28.23	1040	74	21.90
600	0.95	0.99	6	1.5	0.75	510	0.48	106	29.18	1045	75	22.89
900	0.95	0.99	6	1.5	0.75	510	0.48	106	30.86	1057	76	24.98
1200	0.95	0.98	6	1.5	0.75	510	0.48	106	32.02	1063	77	26.33
2200	0.95	0.98	6	1.5	0.75	510	0.48	106	33.16	1070	78	27.70

Abstract

Corrections

Cited By

Figures (10)

Tables (7)

Equations (20)

Applied Optics