ZnO@CdS core–shell thin film: fabrication and enhancement of exciton life time by CdS nanoparticle

In the present study photoluminescence behavior of ZnO and ZnO@CdS core–shell nanorods film has been reported. ZnO nanorods were grown on the glass coated indium tin oxide (ITO) surface by seeding ZnO particle followed with nanorods growth. These nanorods were coated with CdS by chemical bath deposition techniques to have ZnO@CdS thin film and further annealed at 200 °C for their adherence to the ITO surface. The coating was characterized for surface morphology using SEM and optical behavior using UV–visible spectrophotometer. Energy dispersive X-ray (EDX) was used for compositional analysis and time resolve photoluminescence decay for excitons life time measurement. The absorption spectrum reveals that the absorption edge of ZnO@CdS core–shell heterostructure shifted to 480 nm in the visible region whereas ZnO nanorods have absorption maxima at 360 nm. The excitons lifetime of ZnO@CdS was found to be increased with the thickness of the CdS layer on ZnO nanorod. These ZnO@CdS core–shell nanostructures will be of great use in the field of photovoltaic cell and photocatalysis in a UV–visible region.