Dependence of Microstructure and Luminescence on Shell Layers in Colloidal CdSe/CdS Core/Shell Nanocrystals

Colloidal CdSe nanocrystals (NCs) were Successively overcoated with CdS shells, and the X-ray diffraction and Raman measurements of the yielded CdSe/CdS core/shell NCs revealed that stress in the CdSe core was dramatically increased with the growth of the US shell but was released when the shell became thicker. The CdSe lattice contraction, photoluminescence (PL) quantum yield, and PL average lifetime exhibit similar dependences oil the shell thickness. The PL lifetime undulation with temperature is indicative of the spatial distribution of trap states.