Diversified Synthesis of 0D Hybrid Indium Halides Crystal Structure and PLQY Enhancement via Solvent Environment Regulation and Sb ³⁺ Doping

Abstract The controllable synthesis of organic–inorganic hybrid metal halide (OIMH) crystal structures remains a challenge in perovskite materials. Achieving identical chemical compositions with distinct crystal structures through precise reaction control enables varied luminescent properties. By adjusting the solution environment while using the same raw materials, this study reports three new 0D hybrid indium‐based chlorides named separately as: γ‐(HMTA 3+ )InCl 6 (HMTA = hexamethylenetetramine), α‐(HMTA 3+ )InCl 6 , and (C 7 H 15 N 4 + )[InCl 4 (DMSO) 2 ] (DMSO = dimethylsulfoxide). Sb 3+ doping significantly broadens the excitation band of these materials. Under UV excitation, the doped compounds exhibit bright self‐trapped exciton emissions with different colors, enhanced photoluminescence quantum yield of 26.96%, 68.94%, and 89.97%. The symmetry of Indium octahedra is modulated by crystal symmetry, with the high symmetry of γ‐(HMTA 3+ )InCl 6 and α‐(HMTA 3+ )InCl 6 attributed to the quasi‐spherical HTMA 3+ unit. Furthermore, the [InCl 4 (DMSO) 2 ] − octahedral coordination ion, reported for the first time in (C 7 H 15 N 4 + )[InCl 4 (DMSO) 2 ], exhibits greater distortions than common (InCl 6 ) 3− octahedra, which alters the electronic structure of VBM orbitals and broadens the PL excitation band. Additionally, γ‐(HMTA 3+ )InCl 6 exhibits excitation‐dependent emission and white light emission potential at low Sb 3+ doping concentrations, arising from the excited‐state energy transfer between different STE energy levels. This study advances the structural design and luminescence modulation of OIMHs, offering insights for future photophysical applications.