Increasing the Structural Rigidity and Quantum Yield of Highly Emissive Hybrid Antimony Chlorides Using a Diverse Set of Solvent Guests

Abstract 0D organic–inorganic antimony halides have attracted increasing attention due to the non‐toxicity, high stability, and superior photoluminescence quantum yield (PLQY). Here, a series of hybrid antimony chlorides with the same organic cation ethyltriphenylphosphonium (Ph₃EtP⁺), including non‐emissive (Ph₃EtP)₂Sb₂Cl₈ and nine (Ph₃EtP)₂SbCl₅‐based emissive compounds, are synthesized and characterized. These emissive compounds are namely, the guest‐free (Ph₃EtP)₂SbCl₅ and (Ph₃EtP)₂SbCl₅·guest (guest = glycol, acetic acid, methanol, ethanol, n‐propanol, i‐propanol, acetone, and acetonitrile). The solvent used can alter the coordination mode of Sb because the solvation effect affects the reactivity of the anions ([SbCl₄]⁻ and Cl⁻), leading to the formation of either A₂Sb₂Cl₈ or A₂SbCl₅. The solvents can be even incorporated into the crystal structure, where stronger interaction with [SbCl₅]²⁻ leads to higher temperature of the escape of the solvent. The guest molecules could increase the structural rigidity of [SbCl₅]²⁻ via hydrogen bonding and dipole–dipole interactions, which tends to reduce the room‐temperature photoluminescence (PL) Stokes shift and temperature‐dependent PL shift by decreasing the [SbCl₅]²⁻ deformability, along with enhanced PLQY from 81% in guest‐free to near‐unity in (Ph₃EtP)₂SbCl₅·glycol. This work shows that targeted synthesis and diversified choices of solvents provide an efficient tool to generate steady variations in hybrid emissive materials for optoelectronics.