Role of Core-Shell Interfaces on Exciton Recombination in CdSe-CdxZn1-xS Quantum Dots

The shell thickness and composition of CdSe-Cd(x)Zn(1-x)S 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