Toward High-Performance Electron/Hole-Transporting-Layer-Free, Self-Powered CsPbIBr₂ Photodetectors via Interfacial Engineering

Abstract

Self-powered photodetectors (PDs) with inorganic lead halide perovskites hold multiple traits of high sensitivity, fast response, independence from external power supply, and excellent sustainability and stability, thus holding a great promise for practical applications. However, they generally contain high-temperature-processed electron-transporting layers (ETLs) and high-cost, unstable hole-transporting layers (HTLs) coupled with noble metal electrodes, which bring significant obstacles of production cost and stability for their potential commercialization. Herein, we demonstrate the building of high-performance HTL/ETL-free, self-powered CsPbIBr₂ PD with simplified architecture of fluorine-doped tin oxide (FTO)/CsPbIBr₂/carbon upon interfacial modification by polyethyleneimine (PEI). The optimized PD yields a dark current of 2.03 × 10^-9 A, peak responsivity (<i>R</i>) of 0.32 A/W, maximum specific detectivity (<i>D</i>*) of 3.74 × 10¹² Jones, and response time of 1.21 μs. These figures of merit are far beyond those of the one prepared without PEI modification and even the PD containing TiO₂ ETL. Hence, our work suggests a highly feasible route to develop self-powered PDs with significantly simplified fabrication and a reduced production cost.