Effect of carrier trapping on photoexcitation dynamics of green-emitting CdSe nanocrystals

Abstract

Trap states are deeply involved in the photoluminescence (PL) dynamics of semiconductor nanocrystals. This study focuses on the role of trap states in 3 nm CdSe nanocrystals without extra low-energy emission. Trap states create spectral differences at two excitation energies of 3.54 eV and 2.48 eV, as well as a slow PL decay channel with environmental robustness. In temperature-dependent measurements, there is a weakening process of PL quenching, which is consistent with PL lifetime undulation, resulting from the thermal activation of carrier detrapping. Furthermore,the different blue shift levels of PL peaks and PL excitation spectra with temperature was investigated.