Thermochromic Fluorescence of Bi ³⁺ /Sb ³⁺ Co‐Doped (Ph ₃ S) ₂ InCl ₅ Flexible Composites for Optical Temperature Sensing

Abstract By implementing a Bi ³⁺ /Sb ³⁺ co‐doping strategy, the 0D organometallic halide (Ph ₃ S) ₂ InCl ₅ demonstrates tunable dual emission (460 nm blue–610 nm orange) alongside an exceptional photoluminescence quantum yield of 88.8%. Mechanistic studies reveal that the Bi ³⁺ ‐Sb ³⁺ energy transfer governs the fluorescence tunability. Synthesis of flexible fibrous composite materials with >200% elongation at break combined with polydimethylsiloxane (PDMS) through a vacuum curing method. The differentiated thermal quenching effects of the Bi ³⁺ /Sb ³⁺ dual emission peaks are utilized to construct a highly sensitive stretchable temperature sensor with a relative sensitivity of 3.17% K ⁻¹ , achieving non‐contact monitoring of temperature in simulated ice layers with a relative error of 0.2%. Furthermore, dynamic fluorescent color changes (ΔCIE = 0.44) from the mono‐doped and co‐doped systems with temperature variation facilitate the development of a security and information encryption system with multiple response mechanisms, enabling triple information switching under synergistic stimulation from ultraviolet light and temperature. This research provides new insights into the functional design of 0D organic metal halides and the development of flexible optoelectronic devices.