Performance enhancement of a self-powered imaging CsPbBr3 photodetector by tuning the trap effects of carriers

Perovskite photodetectors (PDs) have received extensive attention from researchers due to their potential applications in imaging and visual sensing. Among them, metal-semiconductor-metal (MSM) PDs with a simple preparation process and low cost are considered to be the most suitable structure type for practical applications. However, their applications are limited by their poor responsivities due to the high recombination efficiency of photogenerated electrons and holes in the light-absorbing layer. In this work, carrier traps were introduced into the light-absorbing layer to reduce photo-generated carrier recombination and improve the performance of the PD. PDs based on the CsPbBr3 : ZnO light-absorbing layer are constructed, in which ZnO quantum dots (QDs) act as electron trap states. When the ZnO QD concentration is 1.5 wt% in the light-absorbing layer, the PD shows the best responsivity (about 5.5 times that of the CsPbBr3 PD). A self-powered photodetector was realized by designing a novel planar asymmetric Au interdigital electrode, which modulates the Schottky barrier height at the interface of Au/light-absorbing layer. It exhibits a responsivity of 0.24 mA W-1 under 500 nm light illumination and fast response characteristics (680 ns rise time and 436 mu s decay time) without an external power supply. This work provides a reliable approach and a low-cost strategy to construct high-performance self-powered PDs.