Optimized photoelectric characteristics of MAPbCl3 and MAPbBr3 composite perovskite single crystal heterojunction photodetector

MAPbBr3 single crystal (SC) thin layer was successfully grown on MAPbCl3 SC substrate to form perovskite SC heterojunction. Planar structure electrodes are deposited by thermal evaporation on the surfaces of MAPbCl3, MAPbBr3, and SCs heterojunction, respectively to evaluate their photoelectric performance. The SC heterojunction device exhibits excellent unidirectional conductivity in the voltage-current curves. Meanwhile, the current–time curves prove that SC heterojunction devices can effectively utilize the advantages of MAPbCl3 and MAPbBr3, possessing relatively low dark current (∼300 nA), which is comparable to the dark current of MAPbCl3, but very high photocurrent (∼3500 nA), which is equivalent to the photocurrent of MAPbBr3. Rather than the photocurrent overshot and decay occurring at the exposure of light illumination in the MAPbBr3 device, the photocurrent is extremely stable without overshot and decay in the SC heterojunction device. The light-to-dark ratio of the SC heterojunction device is twice that of MAPbCl3 device and three times that of MAPbBr3 device. Furthermore, the detectivity of the heterojunction device reaches as high as \sim\!\!{\text{7}} \times {\text{1}}{{\text{0}}^{{\text{11}}}}{\text{ Jones}}, an order of magnitude higher than MAPbCl3 and MAPbBr3. The excellent characteristics of SC heterojunction further expand the practical application prospect of perovskite materials.