High pressure photoluminescence and Raman investigations of CdSe∕ZnS core/shell quantum dots

Photoluminescence (PL) and Raman spectroscopies of CdSe∕ZnS core/shell quantum dots (QDs) were studied under hydrostatic pressure (0–160kbars) at room temperature. Two phase transitions, at 69 and 79kbars, respectively, were observed, which correspond to wurtzite-rocksalt and rocksalt-cinnabar structural transformations. The full width at half maximum of PL peaks was found to decrease anomalously approximately 30% with pressure. These experimental data show significant difference between the CdSe∕ZnS core/shell QDs and simple bare CdSe QDs or bulk CdSe, implying the ZnS shell plays a dominant role in structural stability and electronic state of such system.