Unveiling The Role of Cu+ Doping in Rb2AgBr3 Scintillators toward Enhanced Photoluminescence Quantum Efficiency and Light Yield

Doping in luminescent metal halides has become an effective strategy for tailoring the optoelectronic properties. Herein, Cu+ is introduced into Rb2AgBr3 to design the synthesis of Rb2AgBr3:xCu+, which possess cold‐white light emission at room‐temperature without changing the spectral profiles; however, the Cu+ incorporation significantly enhances the photoluminescence quantum efficiency to 98.8% in Rb2AgBr3:0.05Cu+. Additionally, a high scintillation light yield of up to 79 250 photons MeV−1 and a low detection limit of 714.83 nGy s−1 have been achieved via this Cu+ doping engineering. X‐ray imaging with a spatial resolution of up to 5.8 lp mm−1 is further realized using a large scintillator film prepared by mixing polydimethylsiloxane with Cu+ doped Rb2AgBr3 scintillators. This study provides a Cu+ doping design principle for improving both the photoluminescence and scintillation performances of metal halides. Cu+ is introduced into Rb2AgBr3 to design the synthesis of Rb2AgBr3:0.01Cu+ scintillators for X‐ray imaging. The light yield increases from 25 600 for Rb2AgBr3 to 79 250 photons per MeV for Rb2AgBr3:0.01Cu+ with the detection limit of 714.83 nGy s−1 and the spatial resolution of 5.8 lp mm−1 after Cu+‐doping. This study provides a design principle by doping engineering for enhancing the LY property of X‐ray scintillators.