Optimized photoelectric characteristics of MAPbCland MAPbBrcomposite perovskite single crystal heterojunction photodetector.

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