Surface polaron effect on the photoluminescence intensity of CdS quantum dots

Quantum confinement provides a good explanation of the absorption features of quantum dots, but not their photoluminescence structures. A double-potential-well model is proposed to describe the spatial distribution of electronic states to account for the temperature-dependent photoluminescence behaviors in CdS QDs. This model predicts that the polaronic states exist the near surface in semiconductor QDs, there is a barrier between the core state (intrinsic confined state) and the polaronic surface state, and this barrier will decrease with the QD size. These predictions are in good agreement with experimental results.