Competing Energy Transfer-Modulated Dual Emission in Mn-Doped CsNaTbCl Rare-Earth Double Perovskites.

ABBX double perovskites are promising materials due to their outstanding photoelectronic properties and excellent stability in the environment. Herein, we synthesized Mn:CsNaTbCl with dual emission through a solvothermal method for the first time. Mn:CsNaTbCl double perovskites exhibit excellent environmental stability and high photoluminescence quantum yields (PLQYs). The CsNaTbCl was successfully doped with Mn in two modes: at Mn-feeding concentrations below 1%, Mn first tend to insert into the interstitial void, but if the Mn-feeding concentration exceeds 1%, Mn will further substitute Na site of the CsNaTbCl lattice and thus both two doping modes coexist. After Mn doping, efficient energy transfer from the D level of Tb ions to the T level of Mn ions occurs, resulting in tunable dual emission from the TbD → F transition and MnT → A transition. Further, LED based on the Mn:CsNaTbCl double perovskites exhibits excellent performance and stability. This work demonstrates a strategy to achieve novel lanthanide-based double perovskites with potential applications in photonics.