Theoretical investigation on dependence of luminescence properties from CdS/ZnS core-shell quantum dots on core size and quantum confinement

A complete theoretical model is presented in this paper to study the quantum confinement and its effect on optical transitions in a CdS/ZnS core-shell quantum dot. The effect of dot size variation and size distribution on the optical transition in a CdS/ZnS core-shell quantum dot system is discussed in detail. Theoretical calculation reveals the dependency of quantum confinement on shell thickness in a core-shell quantum dot. The study shows a prominent shift in the photoluminescence peak due to change in shell thickness which attributes a change in the depth of conduction and valance band namely band-offset of the core-shell quantum dot system. Our theoretical model can verify reported experimental results successfully which validates our model strongly.