Role of Core–Shell Interfaces on Exciton Recombination in CdSe–Cd_<i>x</i>Zn_1–<i>x</i>S Quantum Dots

Abstract

The shell thickness and composition of CdSe–CdxZn1–xS core–shell quantum dots (QDs) are defining parameters for the efficiency of such materials as light emitters. In this work we present a detailed study into the optical absorption and fluorescence properties of CdSe–CdS, CdSe–Cd0.5Zn0.5S, and CdSe–ZnS QDs as a function of shell thickness. Moreover, the single-exciton recombination dynamics of these systems are analyzed by means of a time-correlated single-photon counting technique and directly related to the specific core–shell interfaces of the various QDs studied using a phenomenological kinetic model. The findings from this model highlight the strong role of the core–shell interface on both steady state photoluminescence and exciton recombination dynamics in these systems.