Integration of temperature sensing and optical anti-counterfeiting in Bi3+/Sb3+ co-doped in-based hybrid halides via STE engineering

Lead-free organic–inorganic hybrid metal halides (OIHMHs) provide an ideal platform for designing multifunctional photonic materials owing to their flexible structure and tunable excited-state dynamics. Herein, excitation-dependent and color-tunable luminescence was achieved in zero-dimensional TEA 2 InCl 5 :Bi 3+ /Sb 3+ , where the coexistence of Bi 3+ - and Sb 3+ -related emissive centers (EM1–EM3) enables broadband emission spanning from blue to orange-red. The phosphor exhibits an impressive PLQY of 55.21 % and remarkable spectral tunability driven by excitation wavelength or dopant ratio modulation. More importantly, the Bi 3+ -related emission demonstrates strong thermal sensitivity of lifetime, yielding a maximum relative sensitivity of 4.76 % K −1 from 90 to 340 K. The thermally activated nonradiative relaxation of self-trapped excitons (STEs) governs this lifetime-dependent optical thermometry behavior. The excitation-dependent color-tunable behavior of the material enabled the realization of multi-level optical anti-counterfeiting patterns. This study provides new insight into excited-state coupling in Bi 3+ /Sb 3+ co-doped OIHMHs and offers a promising route toward high-performance luminescent systems integrating temperature sensing and information security.