Realizing High-Efficiency Yellow Emission of Organic Antimony Halides via Rational Structural Design

Zero-dimensional (0D) organic metal halides have captured extensive attention for their various structures and distinguished optical characteristics. However, achieving efficient emission through rational crystal structure design remains a great challenge, and how the crystal structure affects the photophysical properties of 0D metal halides is currently unclear. Herein, a rational crystal structure regulation strategy in 0D Sb(III)-based metal halides is proposed to realize near-unity photoluminescence quantum yield (PLQY). Specifically, two 0D organic Sb(III)-based compounds with different coordination configurations, namely, (C25H22P)2SbCl5 and (C25H22P)SbCl4 (C25H22P+ = benzyltriphenylphosphonium), were successfully obtained by precisely controlling the ratio of the initial raw materials. (C25H22P)2SbCl5 adopts an octahedral coordination geometry and shows highly efficient broadband yellow emission with a PLQY of 98.6%, while (C25H22P)SbCl4 exhibits a seesaw-shaped [SbCl4]- cluster and does not emit light under photoexcitation. Theoretical calculations reveal that, by rationally controlling the coordination structure, the indirect bandgap of (C25H22P)SbCl4 can be converted to the direct bandgap of (C25H22P)2SbCl5, thus ultimately boosting the emission intensity. Together with efficient emission and outstanding stability of (C25H22P)2SbCl5, a high-performance white-light emitting diode (WLED) with a high luminous efficiency of 31.2 lm W-1 is demonstrated. Our findings provide a novel strategy to regulate the coordination structure of the crystals, so as to rationally optimize the luminescence properties of organic metal halides.