Net energy up-conversion processes in CdSe/CdS (core/shell) quantum dots, a possible pathway to towards optical cooling

The investigation of the possibility of optical refrigeration (OR) on zinc-blende cadmium selenide/cadmium sulfide (CdSe/CdS) core/shell structure quantum dots (QDs) has been carried out. Quality samples were synthesized in our lab, and significant energy up-conversion photoluminescence (UCPL) was observed in these samples, showing the potential of generating net cooling effects. To better understand and predict the UCPL characteristics of the QDs, a semi-empirical model has been developed, showing good agreement with our experimental results. The model takes into account the corresponding quantum yield and cooling efficiency, predicting the possibility of realizing optical refrigeration on a CdSe QDs system.