Efficient energy transfer from self-trapped excitons to Mn2+ dopants in CsCdCl3:Mn2+ perovskite nanocrystals

Mn2+ doping has been adopted as an efficient approach to regulating the luminescence properties of halide perovskite nanocrystals (NCs). However, it is still difficult to understand the interplay of Mn2+ luminescence and the matrix self-trapped exciton (STE) emission therein. In this study, Mn2+-doped CsCdCl3 NCs are prepared by hot injection, in which CsCdCl3 is selected because of its unique crystal structure suitable for STE emission. The blue emission at 441 nm of undoped CsCdCl3 NCs originates from the defect states in the NCs. Mn2+ doping promotes lattice distortion of CsCdCl3 and generates bright orange-red light emission at 656 nm. The energy transfer from the STEs of CsCdCl3 to the excited levels of the Mn2+ ion is confirmed to be a significant factor in achieving efficient luminescence in CsCdCl3:Mn2+ NCs. This work highlights the crucial role of energy transfer from STEs to Mn2+ dopants in Mn2+-doped halide NCs and lays the groundwork for modifying the luminescence of other metal halide perovskite NCs.