Sb3+ Doping Enables Tunable Multicolor Emission and Reversible Thermochromism in Pb-In Binary Hybrid Metal Halides

Abstract Organic–inorganic hybrid multimetal halides possess rich photophysical properties and great potential for multicolor emission and multifunctional optoelectronic applications, but their development is limited by phase separation and the difficulty of integrating multiple luminescent functions. Herein, we report a zero-dimensional Pb-In bimetallic halide, (C9H20N)7[InCl4]2[Pb3Cl11] (C9H20N+ = 1-butyl-1-methylpyrrolidinium), as a structurally well-defined multimetallic crystalline platform. Under 340 nm excitation, the compound exhibits bright green emission at 518 nm with a high PLQY of 96.4%, originating from the [Pb3Cl11]5– cluster tri-polaron formed through phonon-assisted coupling among three [PbCl6]4– octahedra. Upon Sb3+ introduction, an additional broadband red emission at 675 nm appears, associated with Sb3+-related triplet self-trapped exciton (STE) and Sb3+-In3+ donor–acceptor pair (DAP), enabling excitation-dependent tunable emission from green to red. More importantly, under 365 nm excitation, the undoped crystal shows pronounced anti-thermal-quenching behavior, while the Sb3+-doped system exhibits temperature-responsive luminescence regulation and reversible red-orange-green thermochromism over 80–460 K. This work thus integrates efficient cluster-based green emission, Sb3+-induced red emission, antithermal-quenching behavior, and reversible thermochromic response in a single Pb-In multimetallic zero-dimensional crystalline platform, showing promise for solid-state lighting, optical anticounterfeiting, and information encryption.