Synergistic effects of charge transport engineering and passivation enabling efficient inverted perovskite quantum-dot light-emitting diodes

Abstract

All inorganic perovskite quantum dots (QDs) have attracted much attention in optoelectronic devices due to their fascinating properties such as high photoluminescence quantum yields (PLQYs), narrow emission peaks, and facile synthesis processes. Herein, we report a synergistic strategy of interfacial engineering and passivation. We construct an inverted device structure with zinc magnesium oxide (Zn_0.95Mg_0.05O) as an electron transport layer and the p–n charge generation junction of (N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl) benzidine/1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile) as a hole transport layer to facilitate and balance the charge injection/transport. Meanwhile, a facile post-passivation technique is employed to passivate cesium lead bromide (CsPbBr₃) QDs via supplementing Br anions. The treated QDs exhibit improved PLQY due to decreased surface defect sites and enhanced radiative recombination. As a result, our perovskite quantum dot light-emitting diodes (PVQDLEDs) achieve a maximum luminance of 75 792 cd m⁻², an extremely low turn-on voltage of 1.9 V, and a maximum external quantum efficiency (EQE) of 5.95%, leading to an increase in EQE by 100% compared with those of the control device. Our work offers an effective approach to improve the performance of PVQDLEDs via multiple effects for their application in displays and solid-state lighting.