Achieving Exceptional Stability: In Situ Hydrogen Bonding Enables Air-Stable [SbCl6]3– Luminophore with Near-Unity Quantum Yield

Abstract

Lead-free metal halide luminophores offer alternatives to toxic lead-based perovskites, yet octahedral [SbCl6]3– antimony(III) systems suffer rapid moisture-induced degradation within hours despite high photoluminescence quantum yields, limiting practical implementation. (BTMA)2(TMA)SbCl6 (BtTmSbCl), a zero-dimensional hybrid synthesized via solvent-free thermal reaction at 433 K, incorporates benzyltrimethylammonium (BTMA+) and in situ–generated trimethylammonium (TMA+) cations, forming a hydrogen-bonding network that stabilizes isolated [SbCl6]3– octahedra. The material exhibits 95% photoluminescence quantum yield with greenish-yellow emission at 565 nm, matching peak human photopic sensitivity. BtTmSbCl retains ∼95% initial PLQY after 30 days ambient air exposure and maintains stability under continuous UV irradiation, thermal stress, and organic solvents. Self-trapped exciton emission with a large Stokes shift (222 nm), a Huang–Rhys factor of 9.14, and 2.59 μs lifetime enables white LED performance (CRI 82, CCT 5171 K) and applications in security inks, fingerprint detection, and flexible electronics. This work demonstrates design principles for environmentally stable [SbCl6]3– luminophores through synthetic control of hydrogen-bonding architectures.