Photoluminescence and spectral switching of single CdSe/ZnS colloidal nanocrystals in poly(methyl methacrylate)

TL;DR

This study investigates the photoluminescence behavior of single CdSe/ZnS nanocrystals embedded in PMMA, revealing spectral switching phenomena and their dependence on pump power, with implications for understanding nanocrystal emission dynamics.

Contribution

It introduces the observation of spectral switching in single nanocrystals and correlates spectral shifts with phonon replicas, advancing understanding of emission mechanisms.

Findings

Spectral switching occurs between two energy states with similar intensities.

Spectral shift frequency increases with pump power.

Correlation of emission peaks supports phonon replica assignment.

Abstract

Emission from single CdSe nanocrystals in PMMA was investigated. A fraction of the nanocrystals exhibiting switching between two energy states, which have similar total intensities, but distinctly different spectra were observed. We found that the spectral shift characteristic frequency increases with the pump power. By using the dynamic shift in the spectral position of emission peaks, we were able to correlate peaks from the same nanocrystal. The measured correlation is consistent with assignment of low energy lines to phonon replicas.