Pb2+ and Mn2+ Codoped Cs2CdCl4 Nanocrystals with Tunable Emission

2D layered metal halides have gained extensive attention due to their excellent chemical stability and remarkable optoelectronic properties. Herein, Pb2+/Mn2+ codoped Cs2CdCl4 nanocrystals (NCs) were synthesized by a facile hot-injection method. It is found that the Cs2CdCl4:0.6%Pb2+,5%Mn2+ NCs exhibit a photoluminescence quantum yield as high as 18.1%. Tunable emission color from cyan to white and then to orange covering the wavelength range between 400 and 750 nm was achieved by varying the doping concentration of Mn2+ ions in Cs2CdCl4:0.6%Pb2+ NCs. Spectral characterizations and density functional theory calculations reveal that the substantially enhanced Mn2+ emission centered at ∼600 nm is attributed to the efficient energy transfer from self-trapped excitons to Mn2+, with an energy transfer efficiency up to 40%. Importantly, Pb2+/Mn2+ codoped Cs2CdCl4 NCs also exhibit good air and thermal stabilities.