Flexible Single-Crystal\nPerovskite Photodetectors\nvia Polymer-Controlled Transfer

The large-sized perovskite single-crystal sheet (SCS)\nserves as\nthe ideal research platform for perovskite photodetectors due to its\noutstanding carrier photophysics, pronounced geometric aspect ratio,\nand ultrahigh material utilization rate. However, its performance\nin flexible device applications is relatively lackluster due to the\nrigid and brittle nature of the three-dimensional cubic lattices.\nIn this work, the indium tin oxide (ITO)-based multimillimeter-sized\nMAPbBr<sub>3</sub> SCS is transformed into MAPbI<sub>3</sub> SCS via\nion exchange strategy. Significantly, we proposed and implemented\na polymer-controlled transfer strategyutilizing the dichloromethane\n(DCM) solution of poly(methyl methacrylate) (PMMA)to nondestructively\ntransfer the whole perovskite SCS off the ITO substrates and subsequently\nadhere it onto a flexible polyethylene terephthalate (PET) substrate\nof interdigital electrode, thereby fabricating a lateral-structured\nphotodetector with a PMMA-SCS-Au-PET multilayer configuration. The\ntight self-encapsulation between the top PMMA membrane and the bottom\nPET substrate imparts excellent waterproof stability and concurrently\nexcellent mechanical flexibility to these devices; additionally, the\nMAPbI<sub>3</sub> device exhibits comprehensively superior performance\nto the MAPbBr<sub>3</sub> one. This work represents a proactive attempt\nand exploration of the high-performance advancement of large-sized\nSCS photodetectors, undoubtedly introducing novel momentum and solutions\nto this domain.