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.