Effective Energy Transfer Boosts Emission of Rare-Earth Double Perovskites: The Bridge Role of Sb(III) Doping

Halide perovskites have attracted considerable interest due to their excellent photoelectric properties. In this study, we synthesized Sb³⁺-doped Cs₂NaTbCl₆ using a solvothermal method to investigate its tunable photoelectric properties and low toxicity. Upon Sb³⁺ ion doping, the photoluminescence yield (PLQY) of Cs₂NaTbCl₆ significantly increased from ∼1.7 to ∼47%. The introduced Sb³⁺ ions with ns² electronic configuration expanded the rare-earth element's absorption cross section, broke intrinsic forbidden transitions, and suppressed nonradiative recombination. Additionally, the codoping of Sb³⁺ and Mn²⁺ facilitated efficient energy transfer, resulting in highly efficient photoluminescence. The PLQY of 1%Sb³⁺,3%Mn²⁺:Cs₂NaTbCl₆ reached a remarkable 85.8%, marking the highest reported value for rare-earth double perovskites in the visible light region. This study highlights the vital role of Sb(III) doping as a bridging agent to enhance the emission in rare-earth double perovskites.