Carrier accumulation enhanced Auger recombination and inner self-heating-induced spectrum fluctuation in CsPbBr3 perovskite nanocrystal light-emitting devices

Abstract

Light-emitting devices (LEDs) based on colloidal semiconductor nanocrystals (NCs) are promising next-generation thin-film display and lighting devices owing to their high luminescence efficiency and size-tunable color. However, the studies of the carrier transport and recombination mechanisms of the NC-LEDs lag far behind. We study the operation mechanisms of the CsPbBr3 NC-LEDs with a working voltage as high as 40 V. They exhibit an anomalous hump-shaped bias dependence of luminescence intensity. A theoretical model is proposed to explain this, and it indicates that there is enhanced Auger recombination in the CsPbBr3 NC-LEDs caused by imbalanced carrier accumulation, which causes efficiency droop similar to that in the nitride-based light-emitting diodes. We also report the intriguing phenomenon of electroluminescence spectrum fluctuation of the CsPbBr3 NC-LEDs, which is ascribed to the inner self-heating effect in the emission layer.