Enhanced and tunable blue luminescence from CdS nanocrystal-polymer composites

CdS nanocrystals were synthesized by a hydrothermal procedure and dispersed in an aqueous solution. CdS nanocrystal-polystyrene composites were produced by adding the CdS colloids into a toluene solution that contains dissolved polystyrene and casting the mixed solution onto a Si wafer. The photoluminescence from the composites was wavelength-tunable in the blue and its intensity was enhanced sixfold compared to that from the original solution. Raman results give unequivocal information about the origin of the intensity enhancement.