A highly efficient light capturing 2D (nanosheet)-1D (nanorod) combined hierarchical ZnO nanostructure for efficient quantum dot sensitized solar cells.

A novel hierarchical ZnO nanostructure array composed of nanosheet branched (NB) ZnO nanorods (NRs) has been fabricated using a two-step solution reaction. The obtained nanosheet branched (NB) ZnO nanorods (NRs) exhibited considerably enhanced light capturing compared with ZnO thin films and ZnO nanorods. This combined 2D (nanosheet) and 1D (nanorod) hierarchical structure has significant potential as an efficient photoanode for quantum dot-sensitized solar cells (QDSSCs) because the nanosheets provide a large surface area for quantum dot loading and the nanorods present pathways for fast charge transfer. The CdSe/CdS co-sensitized QDSSCs using these nanosheet branched (NB) ZnO nanorods (NRs) as a photoanode exhibit a highly enhanced solar-energy conversion efficiency of 4.4% under conditions of 1 sun illumination.