Excitons and Biexciton Dynamics in Single CsPbBr3 Perovskite Quantum Dots

Colloidal lead halide perovskite quantum dots, due to their optical versatility and facile solution processability, have been recently recognized as components of various optoelectronic devices. Detailed understanding of their exciton recombination dynamics at the single-particle level is necessary for utilizing their full potential. We conducted spectroscopic studies of the excitons and biexciton dynamics in single CsPbBr3 perovskite quantum dots. It was found that while the rates of radiative recombination remain essentially constant, the overall relaxation process is dominated by nonradiative recombination of single excitons and biexcitons. The radiative lifetime scaling is determined to be similar to 1.0 for single exciton and similar to 4.4 for biexcitons. A linear dependence of fluorescence lifetime vs intensity distribution agrees well with the prediction of the model of multiple recombination centers. The blinking mechanism of CsPbBr3 quantum dots is addressed by considering the trion states under higher excitation powers.