Sacrificial additive-assisted film growth endows self-powered CsPbBr3 photodetectors with ultra-low dark current and high sensitivity

Abstract

Inorganic halide perovskite CsPbBr₃ is promising for stable, high-performance self-powered photodetectors (PDs). However, solution-processed polycrystalline CsPbBr₃ films generally exhibit inferior photodetection performance in contrast to single-crystal and micro-/nano-structured counterparts, primarily because of their low carrier mobility and high defect density. We propose herein a sacrificial additive-assisted CsPbBr₃ film growth strategy, in which a 2-phenylethanamine iodide (PEAI) additive was firstly introduced into a CsPbBr₃ precursor film and then was extracted during CsPbBr₃ film crystallization by high-temperature annealing. The as-obtained CsPbBr₃ film exhibits multiple advantages of full coverage, pure phase, micro-sized grains, higher crystallinity, fewer defects, and particularly a CsBr-rich surface with less conductivity, compared with the control film prepared without PEAI sacrificial additive. The resulting self-powered PD with a simple configuration of FTO/TiO₂/CsPbBr₃/carbon yields an ultra-low dark current of 8.05 × 10⁻¹¹ A cm⁻², a high R of 0.35 A W⁻¹, a superior D* of 3.83 × 10¹³ Jones, and a fast response time of 1.46 μs. These figures of merit are far beyond those of the one prepared with the control film and even most of self-powered CsPbBr₃ PDs reported previously. Furthermore, the optimized PD exhibits excellent operational reliability and long-term stability in an ambient air atmosphere.