Polycrystalline perovskite CH₃NH₃PbCl₃/amorphous Ga₂O₃ hybrid structure for high-speed, low-dark current and self-powered UVA photodetector

UVA radiation can survive from the absorption of atmospheric layer and reaches the terrestrial surface, which is harmful to human eyes, blood vessels, and elastic fibers. It is meaningful to detect the UVA radiation precisely. A sensitive, high-detectivity and self-powered UVA detector based on polycrystalline CH₃NH₃PbCl₃/amorphous Ga₂O₃ hybrid structure is presented in this work. Under zero bias, the rise/decay time of the photodetector are 56/67 ms, and the detectivity reaches up to 5.4 × 10¹⁰ Jones. The performance is even superior to most of the reported devices based on CH₃NH₃PbCl₃ single crystal. The heterojunction between amorphous Ga₂O₃ and CH₃NH₃PbCl₃ accelerates the separation of photon-generated carrier and effectively reduces the recombination. In addition, the high resistivity and low surface roughness of the amorphous Ga₂O₃ layer also contribute to the improvement of device parameters. This study offers new insights to improve the polycrystalline MAPbCl₃ devices by ultra-wide bandgap amorphous semiconductors.