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 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 CsPbIxBr3−x film is applied with bi-anion IxBr3−x instead of I3 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 × 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.