A study of charge transfer mechanism and optical properties of Au-CdS core-shell nanocrystals

The enhancement in band edge photoluminescence intensity and Purcell factor associated with red shift in PL features is observed in chemically prepared Au-CdS core-shell nanocrystals. The emission rate is increased by a factor 1.5 in case of Au-CdS core-shell nanocrystals compared to bare CdS nanocrystals, leading to the higher quantum yield. The magnitude of enhancement depends on the area of direct contact between Au and CdS nanocrystals, and hence on the interaction strength. These findings are understood on the basis of charge transfer and mixing of electron energy levels.