Structural Dimensionality Modulation toward Enhanced Photoluminescence Efficiencies of Hybrid Lead‐Free Antimony Halides

Abstract Rationally optimizing the photoluminescence performance via accurate structural modulation is one of most important and challenging issues for hybrid halides. Herein, a viable crystal dimensional reduction strategy is proposed to reasonably enhance the photoluminescence quantum yield (PLQY) of hybrid antimony halide. Specifically, a synthetic technique is developed and new 1D [DMPZ]SbCl₅ ∙ H₂O (DP‐SbCl₅) is sliced to 0D [DMPZ]₂SbCl₆ ∙ Cl ∙ (H₂O)₂ (DP‐SbCl₆) with crystal dimensional reduction from infinite [SbCl₅]²⁻ chain to discrete [SbCl₆]³⁻ octahedron. Comparing with nonluminescent 1D DP‐SbCl₅, 0D DP‐SbCl₆ displays highly efficient broadband yellow light emission with enhanced PLQY up to 75.94%. First‐principles calculation demonstrates that 0D DP‐SbCl₆ features more flat and narrow band structure, which promotes the photoelectron localization and increases the quantum confinement, and finally boosts the luminescence efficiency. Together highly efficient and ultra‐stable luminescence performance enable DP‐SbCl₆ as excellent down‐conversion broadband yellow phosphor to successfully fabricate white light emitting diodes with a high color rendering index of 92. This work provides a novel structural modulation strategy of crystal dimensional reduction to rationally optimize the PL performance of hybrid metal halides.