Model of luminescence and delayed luminescence correlated blinking in single CsPbBr$_3$ nanocrystals

Abstract

Cesium lead halide nanocrystals and quantum dots are prominent materials for different types of applications because of their remarkable photophysical properties. However, they are also known to exhibit the same effects observed for non-perovskite colloidal semiconductor quantum dots such as blinking, photobleaching, delayed luminescence, etc. In this study we reveal the correlations between fast and delayed emission components for both the intensity and characteristic decay time for single CsPbBr$_3$ nanocrystals. In order to explain the phenomena observed, we propose a novel model of single CsPbBr$_3$ nanocrystals luminescence blinking based on the hypothesis of slow variations in the electron-phonon coupling.

Figures (11)

• Figure 1: Data obtained from the experiments with single photon counting. (a) PL intensity time trajectory. (b) Photon distribution function (c) Autocorrelation function estimation and (d) its corresponding power spectral density.
• Figure 2: (a) PL intensity time trajectory (black line) with 2 selected levels (blue and green lines). The red line marks the level that corresponds to the maximum intensity. (b) PL decay curves for selected levels (colored squares) and their fit with biexponential function using Eq.\ref{['biexp']} (red line). (c) Modeled biexponential PL decay (black line). The blue and red colors correspond to the fast and delayed PL components. The ordinate axis in graphs (b) and (c) is shown on a logarithmic scale. The parameters of the modeled curve are $A_F = 0.8$, $\tau_F =10$ ns, $A_D = 0.2$, $\tau_D =100$ ns. The slopes of the blue and red lines give the delay times of the fast and delayed components, respectively. The areas under the blue and red lines show the corresponding relative yields.
• Figure 3: (a) PL intensity trajectory. (b) Fast component characteristic time trajectory. (c) Delayed component characteristic time trajectory. (d) Fast time -- delayed time two-dimensional distribution.
• Figure 4: Two-dimensional distributions obtained by the FLID-like procedure. (a) Fast time -- delayed time distribution (b) Fast time -- fast component relative yield distribution(c) Delayed time -- delayed component relative yield distribution (d) Total relative yield -- short component relative yield distribution.
• Figure 5: (a) Distribution of arrival times of the first photon from a pair detected on two detectors (black squares and circles) and their biexponential fit (red line). (b) Normalized on maximum cross-correlation function at different minimal delay times $T_D$.