Exciton Localization Induced Broadband White Emission in a Stable Zero-Dimensional Hybrid Tin Halide

Low-dimensional hybrid metal halides (MHs) have attracted considerable attention for white light-emitting diodes (WLEDs) due to their outstanding optical properties. However, the toxicity of lead-based hybrid MHs and the poor stability of Sn2+-based counterparts limit their applications. Herein, we rationally designed a zero-dimensional organic–inorganic hybrid tin halide, (4-IBA)2SnCl6, where the spatially isolated [SnCl6]2– octahedra were completely separated by 4-IBA+ organic cations, exhibiting stable broadband warm-white emission with a photoluminescence quantum yield of 24.26%. Combined spectroscopic investigations and density functional theory calculations revealed pronounced exciton localization and strong electron–phonon coupling, inducing the self-trapped exciton emission. Benefiting from the intrinsic oxidation resistance of Sn4+, (4-IBA)2SnCl6 demonstrated markedly enhanced environmental stability compared with conventional Sn2+-based hybrid MHs. Furthermore, a UV-pumped WLED based on the as-prepared phosphor was successfully fabricated, exhibiting Commission Internationale de l’Éclairage coordinates close to the standard white-light region and a high color rendering index of 91.2. This work provides an effective strategy for developing stable, lead-free, single-component white light-emitting tin halide phosphors.