Achieving Ultrahigh Light Yield with Trace Lithium Doping: Synergistic Defect Passivation in Large-Sized Rb₂CuBr₃...

Metal halide scintillators are promising for radiation detection, but their detection performance is limited by inadequate crystal quality and defect-mediated nonradiative recombination. Herein, we report an efficient strategy to overcome the existing limitations by incorporating trace Li⁺ into low-dimensional Rb₂CuBr₃ crystals. This approach modulates the crystallization kinetics and simultaneously induces lattice contraction and effectively suppresses grain-boundary defects, enabling a controllable crystal growth of Li-doped Rb₂CuBr₃ crystals from the micrometer to centimeter scale. X-ray-excited Li-doped Rb₂CuBr₃ crystals exhibited an ultrahigh light yield of 120,871 photons MeV^-1, an excellent imaging resolution of 20 lp mm^-1, and a favorable detection limit of 30 μGy_air s^-1. The breakthrough in luminescence efficiency originates from the unique kinetics of defects under high-energy irradiation; namely, a sharp increase in the exciton concentration effectively passivates nonradiative recombination channels. This study presents a method for preparing large-sized scintillation crystals and reveals a universal mechanism for surpassing intrinsic limits in the performance of Rb₂CuBr₃ scintillating materials via the regulation of defect states, offering promising pathways toward efficient materials for radiation detection.