Optimized photoelectric characteristics of MAPbCl 3 and MAPbBr 3 composite perovskite single crystal heterojunction photodetector.

MAPbBr 3 single crystal (SC) thin layer was successfully grown on MAPbCl 3 SC substrate to form perovskite SC heterojunction. Planar structure electrodes are deposited by thermal evaporation on the surfaces of MAPbCl 3 , MAPbBr 3 , 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 MAPbCl 3 and MAPbBr 3 , possessing relatively low dark current (∼300 nA), which is comparable to the dark current of MAPbCl 3 , but very high photocurrent (∼3500 nA), which is equivalent to the photocurrent of MAPbBr 3 . Rather than the photocurrent overshot and decay occurring at the exposure of light illumination in the MAPbBr 3 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 MAPbCl 3 device and three times that of MAPbBr 3 device. Furthermore, the detectivity of the heterojunction device reaches as high as∼7×1011 Jones, an order of magnitude higher than MAPbCl 3 and MAPbBr 3 . The excellent characteristics of SC heterojunction further expand the practical application prospect of perovskite materials.