Ultrafast photoinduced carrier dynamics at ZnO nanohybrid interfaces for light-harvesting applications

The use of nanoscale materials for efficient solar light harvesting has attracted immense attention in the recent time in order to address the energy and environmental issues. Among them, semiconductor materials such as ZnO have been widely used in the field of photocatalysis and dye-sensitized solar cells (DSSC). However, due to limited visible-light activity and low photo-conversion efficiency, ZnO needs to be modified to design heterostructures with efficient charge separation. Several strategies have been made to modify the wide-bandgap semiconductors including narrow-bandgap semiconductor coupling, noble metal deposition, conducting polymer sensitization and organic dye sensitization. However, the activity of such heterogeneous systems critically depends on the charge dynamics across the involved nanostructured interface. The present review is an effort to unravel the ultrafast dynamical processes across the interface of heterostructures to enhance the solar light-harvesting efficiency. Here, we have discussed few of our selected results covering the different modification strategies of the ZnO nanostructures. The special emphasis has been given to the correlation between the ultrafast processes at the interface and their implications in the light-harvesting applications. The detailed spectroscopic investigations revealing electronic pathways for light harvesting will be helpful in designing future solar devices.