Preparation of Thick Titanium Dioxide Films by Repeated Electrolysis-Calcination for Dye-Sensitized Solar Cells

Titanium dioxide (TiO2) films were prepared by cathodic galvanostatic electrolysis of a solution of titanium bis(ammonium lactato)dihydroxide (TALH) and ammonium nitrate (NH4NO3) at 323 K on a transparent conducting substrate (fluorine-doped tin oxide; PTO) and calcination at 723 K. The effect of NH4NO3 concentration on the deposition rate and quality of films was investigated. An active electrodeposition of the films was observed after the calcination of previously electrodeposited layers. A mechanism for the film growth at widened crack spaces within the deposits by calcination was proposed. The TiO2 films were thickened beyond 5 mu m by four repeated electrolysis-calcination cycles. The energy conversion efficiency of a dye-sensitized solar cell fabricated using TiO2 films could be optimized to 5.15% by controlling the electrolysis current. (C) 2014 The Electrochemical Society. All rights reserved.