Concentration dependence of photoluminescence properties and exciton dynamics in Mn:CsPb(BrCl)3 quantum dots

All-inorganic lead halide perovskite quantum dots (IPQDs) display some intriguing magnetic, electronic, and optical properties by introducing a transition metal Mn element. In this Letter, Mn-doped CsPb(BrCl)3 IPQDs with a cubic structure have been synthesized by the hot injection method. What make us excited is that the photoluminescence properties of a fixed ensemble of Mn-doped CsPb(BrCl)3 IPQDs systematically depend on the varying concentration. This experimental phenomenon can be well explained by the quantitative model based on photon reabsorption. The results combining experiments with theoretical models indicate that the photon reabsorption is of paramount importance in the analysis of the luminescence properties of colloidal quantum dots especially at high concentrations. Further analysis based on time-resolved fluorescence and transient absorption spectroscopy reveals the effect of the solution concentration on the Mn-doped CsPb(BrCl)3 IPQD exciton dynamics. The results suggest that exciton energy transfer can take place both inside and between IPQDs and also can be enhanced by increasing the concentration of a Mn-doped CsPb(BrCl)3 IPQD solution. These results are of great significance to accurately interpret and control the luminescence properties of IPQDs.