High quantum yield of In‐based halide perovskites for white light emission and flexible x‐ray scintillators

Abstract In‐based halides always present low photoluminescence quantum yield (PLQY) because of poor absorption, limiting their potential applications in luminescence‐related fields. In this work, zero‐dimensional MA4InCl7 [MA+: CH3NH3+] halides with different Sb3+ doping level are prepared through solvent evaporating method. The Sb3+‐doped MA4InCl7 shows a broadband yellow emission with full width at half‐maximum of 180 nm and a high PLQY of 84%. Such broadband emission originates from the self‐trapped excitons demonstrated by experimental results and theoretical calculations. Additionally, the Sb3+‐doped MA4InCl7 is further employed to fabricate white‐light‐emitting diodes, which possesses high color rendering index of 91 and excellent operating stability up to 400 h. Moreover, flexible Sb3+‐doped MA4InCl7 films are also prepared as x‐ray scintillators, exhibiting low detection limit of 63.3 nGyair/s and high spatial resolution of 10.0 lp/mm. Thus, this work provides guidance to design perovskite‐based devices with bright luminescence and x‐ray detection with excellent flexibility.