Improved performance of CsPbBr3 light-emitting diodes based on zinc bromide passivated quantum dots

Abstract

Metal halide perovskite quantum dots (Pe QDs) have aroused tremendous interest in the past several years for their promising applications in display and lighting. However, an inevitable precipitation and purification process has to be conducted to clear away redundant uncoordinated organic ligands during the synthesis of QDs, leading to the formation of surface vacancy defects. Herein, an ion replenishment process has been demonstrated to passivate cesium lead bromide QDs (CsPbBr3 QDs) with zinc bromide (ZnBr2) without cosolvent. This technology does not introduce any more process of QDs synthesis, ZnBr2 has been utilized as the inorganic additive dispersed in antisolvent ethyl acetate during the precipitation and purification. The formation of both lead ions (Pb2+) and bromide ions (Br−) vacancy defects could be suppressed. Improved radiative recombination and stability were achieved. As a result, light-emitting diodes (LEDs) based on the CsPbBr3 QDs with ZnBr2 exhibited an maximum luminance of 96392 cd m−2, current efficiency of 21.1 cd A−1 and external quantum efficiency (EQE) of. Compared with the devices fabricated from Pe QDs without passivation, the enhancement of maximum luminance and EQE is up to 200% and 100%. This work provides a simple and effective strategy to passivate the surface vacancy defects of CsPbBr3 QDs.