A visible light detector based on a heterojunction phototransistor with a highly stable inorganic CsPbIxBr3−x perovskite and In–Ga–Zn–O semiconductor double-layer

Abstract

An all-inorganic heterojunction phototransistor using a highly stable perovskite (CsPbI_xBr_3−x) and amorphous In–Ga–Zn–O (IGZO) double-layer is introduced to enhance the sensing performance of optoelectronic devices and to expand their detecting range from the ultraviolet to the visible light region. Despite the high-performance photoelectric properties of CsPbI₃ perovskites retaining the α-phase, actual applications of the perovskite film are considerably hindered by the phase instability under ambient conditions. Here, in order to improve the long-term stability of the α-phase perovskite, we propose a multiple anion strategy in the perovskite structure. The developed CsPbI_xBr_3−x film is applied with bi-anion I_xBr_3−x instead of I₃ by adding CsBr and PbBr₂ in the CsPbI₃ precursor solution. Using the optimized CsPbI_xBr_3−x film with 12 wt% of the additives CsBr and PbBr₂ in the CsPbI₃ precursor solution, we demonstrate an all-inorganic visible light detector based on a heterojunction phototransistor with a p⁺⁺-Si/SiO₂/IGZO/CsPbI_xBr_3−x/Ti–Al–Ti structure, in which IGZO and CsPbI_xBr_3−x are used as a charge transport layer and a light absorption layer, respectively. The phototransistor exhibits a responsivity of 26.48 A W⁻¹, a detectivity of 8.42 × 10¹⁴ Jones, and an external quantum efficiency of 51% under visible light illumination (635 nm). In particular, it shows excellent stability over 1 month under ambient conditions.