Heavy-atom effect regulating room temperature phosphorescence in hybrid metal halide glasses

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 <i>via</i> 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 (<i>e.g.</i>, [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.