A novel photoanode architecture of dye-sensitized solar cells based on TiO2 hollow sphere/nanorod array double-layer film

A novel TiO2 double-layer (DL) film consisting of TiO2 hollow spheres (HSs) as overlayer and single-crystalline TiO2 nanorod arrays (RAs) as underlayer was designed as the photoanode of dye-sensitized solar cells (DSSCs). This new-typed TiO2 HS/RA DL film could significantly improve the efficiency of DSSCs owing to its synergic effects, i.e. the relatively large specific surface area of TiO2 HSs for effective dye adsorption, enhanced light harvesting capability originated from TiO2 RA film, and rapid interfacial electron transport in one-dimensional TiO2 nanorod arrays. The overall energy-conversion efficiency of 4.57% was achieved by the formation of TiO2 DL film, which is 16% higher than that formed by TiO2 HS film and far larger than that formed by TiO2 RA film (eta = 0.99%). The light absorption and interfacial electron transport, which play important roles in the efficiency of DSSCs, were investigated by UV-vis absorption spectra and electrochemical impedance spectra. (C) 2011 Elsevier Inc. All rights reserved.