Suppression of Mid‐Gap Trap State in CsPbBr3 Nanocrystals with Br‐Passivation for Self‐Powered Photodetector

Abstract

All‐inorganic halide perovskite nanocrystals (NCs) have attracted great attention, prized for their excellent photophysical properties. However, the insulating nature of alkylamine ligands impede the electrical performance of optoelectronic devices. The control content of passivating ligands and suppression of mid‐gap trap state from perovskite NCs is an essential step to boost the device performance. Therefore, in this report a facile one step ligand‐exchange procedure is employed by rinsing the perovskite film into excess of bromide content to passivate surface trap state along with the suppression of native alkylamine ligands. Remarkably, owing to the vacancies filling potential of cesium bromide, hysteresis behavior in the treated perovskite film was significantly suppressed. More importantly, the absorption and photoluminescence intensities as well as photoluminescence quantum yield of bromide passivated films were improved. The heterojunction photodetector based on the configuration of indium tin oxide (ITO)/ZnO/CsPbBr3‐CsBr/Au revealed a higher responsivity of 6.38 A W−1, fast response time of 270/277 ms and a higher value of specific detectivity 2.6 × 1013 Jones. This work provide a facile and effective approach to effectively passivate the surface trap states from perovskite NCs with control value of native alkylamine ligands. The simple device architecture further provides a promising approach to fabricate high performance self‐powered photodetectors.