Currently,perovskite solar cells(PSCs)based on polycrystalline absorbers reach a certified power conversion efficiency(PCE)of 25.2％[1].However,the further advance of the PCE has been impeded by intrinsic defects located at the surface or grain bound-aries of polycrystalline perovskite films[2-4].According to the les-sons learned from Si solar cells,potential ultrahigh PCE of 30％close to the Shockley-Queisser limit is theoretically achievable by emerging a monocrystalline perovskite absorber[5].Experimen-tally,the perovskite single crystals show longer diffusion length,lower defect density and thus improved stability under external stresses.Therefore,the growth of sub-micrometer thin,laterally large and monocrystalline perovskite film is urgently required for highly-efficient optoelectronics including solar cells,light-emitting diodes(LEDs),photodetectors,etc.