Non-exponential photoluminescence kinetics in CsPbBr3 nanocrystals in glass matrix

Lead-halide perovskite nanocrystals (NCs) are a new class of semiconducting materials with bright photoluminescence (PL) in the visible spectral range, which is promising for various applications. In the present work, the PL kinetics of CsPbBr3 NCs in a glass matrix are experimentally studied. The NCs reveal strongly non-exponential kinetics, whose long-lived tail can be observed up to a fraction of microsecond at low temperature. A model of the kinetics is developed, which considers the presence of surface traps in the NCs, capturing photogenerated charge carriers. The distribution of trap energies over some interval in the NC ensemble is taken into account. Thermal activation of carriers from the traps explains the shortening of the PL kinetics with the temperature increase observed experimentally. The model contains three free parameters. Two of them can be fixed, and the third parameter, the minimum trap energy Es, linearly increases with the temperature increase. Comparing the temperature dependencies of Es and the energy shift of the PL band, we conclude that the trap energy is pinned by the glass matrix surrounding the NCs.