Regulation of Afterglow and Self-Trapped Exciton Emission in Indium-Based Organic Metal Halides via Metal Ion Doping for Multilevel Anti-Counterfeiting

Abstract

Zero-dimensional hybrid metal halides (0D HMHs) have sparked extensive research in the field of optoelectronic materials due to their unique physical and chemical properties. This work innovatively incorporates In³⁺ into a triphenyl-sulfide-based organic phosphorescent system, successfully constructing a novel 0D hybrid metal halide, (Ph₃S)₂InCl₅. This new material achieves a synergistic output of blue photoluminescence (PL) and green afterglow, which originating from the intrinsic excitation of [Ph₃S]⁺. Through ns² metal ions (Bi³⁺/Sb³⁺) doping engineering, a dual-channel energy transfer pathway is established, enabling the transition from singlet and triplet states to self-trapped exciton states, thereby achieving dynamic control of fluorescence and phosphorescence emissions. Additionally, temperature-dependent PL spectra, time-resolved photoluminescence (TRPL), and Raman spectroscopy are employed to investigate the enhanced photoluminescence of the doped samples, revealing the process of STE (self-trapped excitons) recombination and the electron-phonon coupling processes. It is also found that defect states introduced by Sb³⁺ doping lead to thermoluminescence with tunable color output, and explores its applications in temperature-sensitive materials based on fluorescence peak positioning. Based on these findings, a phosphorescence-PL dual-mode dynamic switching encryption system is constructed, utilizing a time-resolved multi-level decryption strategy to achieve high-order optical anti-counterfeiting. This work not only aids in the in-depth understanding of STE formation in In-based organic metal halides but also provides important guidance for the modulation strategy of STE and afterglow emissions in other 0D HMH luminescent materials.