Single-crystalline rutile TiO2 nanorod arrays with high surface area for enhanced conversion efficiency in dye-sensitized solar cells

Abstract

Vertically ordered single-crystalline TiO2 nanorod arrays (NRAs) grown directly on transparent conductive substrates are of considerable interest for overcoming the limitations of current nanoparticle-based dye-sensitized solar cells (DSSCs) with the disordered network structure. However, the synthesis of such structures with high internal surface area is still challenging and desirable for highly efficient DSSCs. Herein, by introduction of a TiO2 nanocrystal seed layer, growth of long single-crystalline rutile TiO2 NRAs with high surface area has been demonstrated by a mild hydrothermal method combined with a chemical etching route. The chemical etching treatment developed here can effectively enlarge the surface area of rutile TiO2 NRAs for more dye-loading by splitting of original TiO2 nanorods into secondary nanowires with a reduced diameter. Accordingly, a DSSC constructed by 7 h-etched rutile TiO2 NRAs exhibits markedly enhanced efficiency of 4.69 %, compared to that of 1.30 % in the DSSCs based on un-etched TiO2 NRAs.