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Self-trapped exciton (STE) emission stands out for its large Stokes shift, broad emission spectrum, and high photoluminescence quantum yield (PLQY). In this work, we developed an Sb 3+ -doped low-dimensional layered halide, Cs 2 CdBr 2 Cl 2, as a system to achieve efficient broadband emission. By fine-tuning the Sb 3+ doping concentration, we induced moderate lattice distortion, resulting in a suitable Huang–Rhys facto r ( S = 18.00) and a high exciton binding energy ( E b = 144.73 meV), which collectively enabled strong yellow STE emission with a PLQY of nearly 80%. Experimental and theoretical investigations reveal that the emission originates from STE states associated with distorted SbCl 4 Br 2 3– octahedra. This highly efficient luminescent material, when combined with commercial phosphors, achieves a high color rendering index (Ra) of 90.8 and exhibits excellent radiation resistance and great potential for X-ray imaging applications.
Tong et al. (Thu,) studied this question.