Recent progress of ZnO hierarchical nanostructure for photovoltaic application

Highly efficient utilisation of solar energy is regarded as one of the most promising renewable energy solution. Enormous efforts have been dedicated to both the material and configuration to achieve an optimised efficient charge separation, transport and collection processes. Hierarchical nanostructures with controlled morphology and dimensionality have attracted enormous attention for their high specific surface area, tailored topology and distinct electro-optical properties. To date, various advances have been made using hierarchical nanomaterials for photovoltaic applications. Herein, recent advances in the ZnO hierarchical nanostructures for photovoltaic solar cells are reviewed. Three representative solar cell configurations, i.e., DSSC, QDSC, and hybrid solar cells, are discussed. The impact of the ZnO hierarchical nanostructure on the overall performance is highlighted to elucidate the advantages of the high-densely branched nanostructure in efficient light adsorption and transfer. The summary and outlook for the ZnO nanomaterial-based solar cells is provided at the end of the review.