0013-4651/2012/159(8)/H711/5/$28.00 © The Electrochemical Society Surface States and Electronic Structures of Various Sintered TiO2 Photoanodes for Use in Dye-Sensitized Solar Cells

Photoanodes used in dye-sensitized solar cells were prepared by sintering hydrothermally synthesized particles under different gases. The obtained photoanodes were then characterized for the crystalline and electronic structures, the surface chemistry, and dye loading capability. The performance of solar cells having the obtained photoelectrodes was evaluated by both the overall conversion efficiency and incident photon-to-electron conversion efficiency. The facile approach of sintering TiO2 under different gases was found to vary the electronic structure and, particularly, the surface state of the TiO2. As compared to the air-sintered film, the nitrogen-and oxygen-sintered TiO2 films reduce the amount of oxygen vacancies and thus increase the Ti4+ (TiO2) concentration, as evident by Ti L-edge and O K-edge X-ray absorption spectra. X-ray photoelectron spectroscopy analysis also shows the same result. It was found that the oxygen-sintered photoanode exhibit the highest oxidation state and has the highest amount of surface C-OH functional group, leading to a 20 % increase in the cell efficiency as compare to the cell having the air-sintered TiO2 photoanode. The effect of the resulting TiO2 photoanode characteristics on the cell performance is also discussed