Heavy-Atom Effect Regulating Room Temperature Phosphorescence in Hybrid Metal Halide Glasses

Abstract

Room-temperature phosphorescence (RTP) in hybrid metal halide glasses offers promising applications in optoelectronics and anti-counterfeiting, yet achieving tunable RTP properties remains challenging. Here, we report a solvent-assisted rapid evaporation method to synthesize a series of zero-dimensional (0D) butyltriphenylphosphonium-based (BuTPP⁺) hybrid metal halide glasses with the composition (BuTPP)2MCl2X2 (M = Zn, Cd; X = Cl, Br, I). By incorporating optically inert heavy-atom-containing metal halide units [MCl2X2]2‾, we demonstrate precise regulation of RTP lifetimes via the heavy-atom effect, with lifetimes decreasing from 608.6 ms for (BuTPP)2ZnCl4 to 146 ms for (BuTPP)2CdCl2Br2 as the atomic number of inorganic metal halide units increases. Notably, when the atomic number exceeds 170 (e.g., [ZnCl2I2]2‾ and [CdCl2I2]2‾), self-trapped exciton (STE) emissions dominate, completely suppressing organic afterglow. Furthermore, (BuTPP)2ZnCl4 glass exhibits excitation-dependent multicolor phosphorescence due to aggregate cluster luminescence. These glasses showcase dual-mode emissions (RTP/STE) and are successfully applied in shape-controllable anti-counterfeiting and high-resolution X-ray scintillation imaging (10 lp mm-1). This work provides a facile vitrification strategy and design principles for hybrid RTP materials with tailored photophysical properties.