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

An all-inorganic heterojunction phototransistor using a highly stable perovskite (CsPbIxBr3-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 alpha-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 alpha-phase perovskite, we propose a multiple anion strategy in the perovskite structure. The developed CsPbIxBr3-x film is applied with bi-anion IxBr3-x instead of I-3 by adding CsBr and PbBr2 in the CsPbI3 precursor solution. Using the optimized CsPbIxBr3-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/CsPbIxBr3-x/Ti-Al-Ti structure, in which IGZO and CsPbIxBr3-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 x 10(14) 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.