Exciton radiative recombination in spherical CdS∕CdSe∕CdS quantum-well nanostructures

Abstract

Photoluminescence (PL) and lifetimes of colloidal CdS∕CdSe∕CdS (core∕well∕shell) quantum-well (QW) nanostructures are investigated for different well thicknesses in the temperature range of 77–300K. When the temperature increases, the PL intensity decreases continuously and PL peak shifts to lower energy side. The PL lifetimes for the 1–3 monolayer (ML) CdSe QWs increase with temperature and radiative recombination dominates the decay processes. The radiative lifetimes basically increase linearly with temperature, which indicates the existence of free two-dimensional excitons. For the 4 ML CdSe QW sample, the lifetime does not increase with temperature, showing more nonradiative processes due to more defect formation within the thicker QWs.