Enhanced Exciton‐to‐Mn2+ Energy Transfer in 3D/0D Cesium–Lead–Chloride Composite Perovskites

Doping cesium lead halide perovskite nanocrystals (NCs) with Mn2+ brings attractive long‐wavelength emission and flexible color tunability. However, due to multiple competing factors, the exciton‐to‐Mn2+ energy transfer efficiency is low. In this work, a simple structure‐optimization strategy is applied to enhance the exciton‐to‐Mn2+ energy transfer by synthesizing Mn2+ activated 3D/0D Cs–Pb–Cl perovskite composition composed of 3D CsPbCl3 and 0D Cs4PbCl6 NCs. The results reveal that the energy transfer efficiency and the photoluminescence quantum efficiency of the Cs–Pb–Cl composite are 65.3% and 77.3%, respectively, which are 1.4 and 3 times the corresponding values of the single‐phase CsPbCl3:Mn2+ NCs. Based on the detailed experimental and calculation results, the performance enhancement is demonstrated to stem from the optimized growth process of 3D CsPbCl3 NCs when co‐generating with 0D Cs4PbCl6 NCs. The strong lattice rigidity of the optimized CsPbCl3 NCs suppresses the nonradiative combination rate of the excitons, thus alleviating the main competing factor of the energy transfer process and improving the energy transfer efficiency. Fabrication of a white light‐emitting diode prototype further illustrates the application potential of the orange‐emitting Cs–Pb–Cl composite NCs for general lighting. Mn2+‐doped 3D/0D Cs–Pb–Cl composite perovskites, in which the growth of 3D CsPbCl3 nanocrystals (NCs) is optimized by co‐generation of 0D Cs4PbCl6 NCs, exhibit a single emission band of Mn2+ with 1.4 and 3 times enhanced energy transfer and photoluminescence quantum efficiency compared to the single‐phase CsPbCl3:Mn2+ NCs.