Bright and Stable Purple/Blue Emitting CdS/ZnS Core/Shell Nanocrystals Grown by Thermal Cycling Using a Single-Source Precursor

A new approach for synthesis of high quality core/shell nanocrystals, thermal-cycling coupled single precursor (TC-SP), was developed. It was applied for the synthesis of high efficiency, good color purity, nearly monodisperse, alloying-free, and stable CdS/ZnS core/shell nanocrystals with their emission peak tunable between 375 and 475 nm. A comparison study on TC-SP versus the classic successive ionic layer adsorption and reaction (SILAR), both in one pot, revealed that, although the reaction temperature was significantly reduced and the procedure was simplified for TC-SP, the overall quality of the CdS/ZnS core/shell nanocrystals yielded by TC-SP was found to be superior. A quantitative chemical etching method was developed for determining the radial distribution of elements in bandgap/composition engineered nanocrystals.