High Quantum Efficiency of Stable Sb‐Based Perovskite‐Like Halides toward White Light Emission and Flexible X‐Ray Imaging

Abstract Although low‐dimensional hybrid metal halides have emerged as promising light emitters due to their broadband emission originated from self‐trapped exciton (STE), the synthesis of lead‐free halides with high photoluminescence quantum yield remains a challenge. Herein, a series of new luminescent single crystals of antimony‐based metal halides [Na(DMSO)₂]₃SbBr_6−xCl_x (x = 0, 2, 3, 4, 6) is synthesized. By optimizing the ratio of Br and Cl, [Na(DMSO)₂]₃SbBr₃Cl₃ exhibits an ultra‐broadband yellow light emission peaking at 606 nm with a full width at half‐maximum of 160 nm and a high photoluminescence quantum yield of 90.6%. Both experimental characterizations and theoretical calculations indicate that STE emission is responsible for the ultra‐broadband yellow light emission. Furthermore, blue LED chip‐pumped white light‐emitting diodes by using the yellow‐emitting [Na(DMSO)₂]₃SbBr₃Cl₃ are demonstrated, showing a correlated color temperature of 3948 K and a color rendering index of 85. Finally, a large‐size and flexible [Na(DMSO)₂]₃SbBr₃Cl₃ scintillator used for X‐ray imaging is prepared by a template assembled method, exhibiting a high spatial resolution of 15.5 lp mm⁻¹ and a low detection limit of 285.8 nGyair s⁻¹. This work highlights the potential of Sb‐based halides in solid‐state illumination and X‐ray imaging.