ZnO hierarchial structure prepared via direct precipitation for dye-sensitized solar cells

Abstract

A ZnO hierarchical structure was prepared via simple aqueous method at room temperature using zinc nitrate solution as precursor. Time-dependent trails demonstrated the formation of the hierarchical structure results from the Ostwald ripening effect. The ZnO hierarchical structure was further applied as photoanode in dye-sensitized solar cells (DSSCs), and a conversion efficiency of 2.36 % was demonstrated, which is higher than that of commercial ZnO-based DSSCs of 1.39 %. Based on the optical and electrochemical investigations, the high conversion efficiency was mainly ascribed to the unique structure of ZnO. The hierarchical structure can enhance the dye-loading capacity, and the hierarchical structure with micrometer-sized diameter could improve the scattering effect. Moreover, the good crystallinity can reduce the grain boundaries, suppress the recombination loss, and provide a fast electron transport, which therefore enhanced the conversion efficiency of cells.