Solvent‐Induced Bright Emission in Lead‐Free Organic–Inorganic Antimony Bromides with Reversible Transformation

Abstract Lead‐free low‐dimensional organic–inorganic metal halides have gained increasing attention in a wide range of applications due to their low toxicity, outstanding optical performance, and structural tunability. In this work, a general method of incorporating organic molecule into sodium antimony bromides is introduced. The 1D Na₃SbBr₆(C₂H₆OS)₆ and Na₃SbBr₆(C₄H₈OS)₆ single crystals exhibit bright yellow and orange emission with PL peaks at 610 and 664 nm, and high photoluminescence quantum yields (PLQYs) of 85% and 60%, respectively. These two compounds can be reversibly converted into each other by the removal and addition of the organic components. Their exceptional luminescent performance enables them to be used as solid‐state phosphors for the fabrication of yellow and orange down‐conversion LEDs. A white LED with a high color rendering index (CRI) of 95 is also fabricated by using Na₃SbBr₆(C₂H₆OS)₆ as the yellow phosphor. The universality of this method is demonstrated by synthesizing other members of this family with diverse A‐groups, including methylammonium (MA) and formamidinium (FA). This work provides an effective strategy for the development of diverse lead‐free and high‐performance organic–inorganic hybrid materials and indicates these organic–inorganic hybrid compounds are promising luminescent materials for lighting or displays.