Enhancing Luminescence in Hue-Tunable White-Light Emitting K 4 CdCl 6 :Sb 3+ ,Mn 2+ All-Inorganic Halide Perovskites: Insights from Defect Engineering and Energy Transfer.

All-inorganic halide perovskites (AIHPs) have emerged as highly promising optoelectronic materials owing to their remarkable properties, such as high-optical absorption coefficients, photoluminescence efficiencies, and dopant tolerance. Here, we investigate the AIHPs KCdCl:Sb,Mn that demonstrate hue-tunable white-light emission with an exceptional photoluminescence quantum yield of up to 97%. Through a detailed investigation, we reveal that efficient energy transfer from Sb to Mn plays a dominant role in the photoluminescence of Mn, instead of the conventional T → A transition of Mn. Thermodynamic analysis highlights the crucial role of a Cl-rich environment in obtaining the KCdCl phase, while transformation from KCdCl to KCdCl can be achieved under Cl-poor and K-poor conditions. The theoretical analysis reveals that defect is more readily formed compared to defect , corroborating experimental findings that the KCdCl:Sb phase is exclusively obtained when the solution contains HCl concentrations higher than 4 mol L. Our work provides valuable insights into the photoluminescence mechanism of Sb, defect engineering through heterovalent doping, and efficient energy transfer between Sb and Mn in K-Cd-Cl-based perovskites, which offers a new perspective for the design and development of novel AIHPs with superior optoelectronic performance.