Controllable Fabrication of Clustered Quantum Dots for Time-Correlated Hyperspectral Studies

Optical properties of clustered core(CdSe)-Shell(ZnS) quantum dots (QDs) are investigated.  Monomers, dimers, and trimers of QDs are generated through a self-induced droplet assembly using an electrospray differential mobility analyzer.  A fixed number of QDs in the clusters is achieved through controlled electrostatic deposition.  QD clusters composed of both homoclusters and heteroclusters are generated.  Multimodal time-correlated hyperspectral studies of these QD clusters are carried out, simultaneously measuring the dynamic photoluminescence (PL) intermittencies, PL life times, and spectral diffusion revealing the unique properties of interacting QDs in QD clusters under photooxidation.  Controlled assembly of a fixed number of QDs into single clusters and analysis of their dynamic PL properties leads to better understanding of the excitonic charge transfer (photonic to electronic energy transfer) during photooxidation in single and clustered QDs.  The clustered QDs will provide unique optical characteristics which will be beneficial for applications in energy devices such as solar cells and devices with a long-term photostability.  Analysis of homoclusters and heteroclusters reveals a distinct variation in their optical properties which will lead to interesting aspects for QD based energy devices.