Atomic Layer Deposition of Ta-doped TiO2 Electrodes for Dye-Sensitized Solar Cells

Ta-doped TiO2 inverse opals were obtained by selective etching of a silica template after atomic layer deposition (ALD) of Ta-doped TiO2 films and were applied as an electrode for dye-sensitized solar cells (DSSCs). Ta content in the Ta-doped TiO2 film was controlled by the Ta/(Ta+Ti) unitcycle ratios in the Ta-TiO2 supercycle of ALD. Also, excellent step coverage of nearly 100% in the inverse opal structure was confirmed by field-emission scanning electron microscopy (FE-SEM). Maximum photo-conversion efficiency of 1.56% was achieved with the Ta (3.4 atom %)-doped TiO2 inverse opal electrode due to increased photocurrent density. However, further Ta doping (> 4.9 atom %) decreased the J(sc) and photoconversion efficiency. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3582765] All rights reserved.