Photoluminescence blinking and spectral diffusion of single CdSe/ZnS nanocrystals: charge fluctuation effects

We studied time-dependent fluctuations of photoluminescence (PL) spectra of single CdSe/ZnS nanocrystals (NCs), which show PL blinking and spectral diffusion. We observed correlations between PL peak energy, intensity, and linewidth, which are due to the quantum confined Stark effect. We found that a characteristic asymmetric shape appears in the PL peak energy histogram, which can be explained by a simple field-fluctuation model. By comparing the experimental results with theoretical calculations, we evaluate the mean value and standard deviation of the fluctuating electric field. We discuss the experimental data using a model considering a few elementary charges around the NCs, which are the origin of the field fluctuation.