Colloidal quantum dot light-emitting diodes (QLEDs) are recognized as promising candidates for next generation displays. In this talk, we will review our recent progress on QLEDs, particularly emphasizing the influence of device structures on the performance of QLEDs. Various device structures including top-emitting, microcavity, inverted, tandem, transparent, full-solution vacuum-free processed QLEDs will be talked. Charge balance is carefully optimized in these structures. In addition, we show that the defect concentration of ZnO can significantly quench the emission and thus reduces the performance of QLEDs. By substituting the problematic ZnO with ZnxMg1-xO, the efficiency of QLEDs can be largely improved. With the strategies mentioned above, our recently developed vacuum-free processed tandem QLEDs exhibit current efficiency and external quantum efficiency (EQE) over 100 cd/A and 23.5%, respectively.
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