Excitation-Controlled Singlet–Triplet Channel Redistribution in a Stable 0D Sn(II) Hybrid Halide

Lead-free organic–inorganic metal halides (OIMHs) with robust zero-dimensional (0D) frameworks are highly attractive for practical optoelectronic applications. Here, we propose a precursor-engineering strategy using the organic molecule C15H15N to stabilize Sn-based metal halide thin films. Four 0D OIMHs were synthesized via a solution method, namely, (C15H16N)4SnCl6, (C15H16N)2SnBr6, (C15H16N)6BiBr9·2H2O, and (C15H16N)3(C2H8N)BiBr7·H2O, all adopting 0D structures. (C15H16N)4SnCl6 exhibits excitation-dependent multichannel photoluminescence: under 370 nm excitation it shows blue–white emission, whereas 306 nm excitation yields two bands at 410 and 750 nm, indicating multiple emissive centers. Time-resolved photoluminescence and density functional theory calculations reveal distinct emissive channels from the organic cation and Sn2+ centers, evidencing excitation-controlled redistribution among singlet and triplet manifolds within the rigid 0D framework. (C15H16N)4SnCl6 shows excellent stability and optical properties, and when combined with polymers to form composite films, its excitation-dependent luminescence offers a highly promising route for information encryption.