Electrophoretic deposition of TiO2 film on titanium foil for a flexible dye-sensitized solar cell

Electrophoretic deposition (EPD) method is employed to obtain mesoporous TiO2 film on a titanium (Ti) foil; the film is then mechanically compressed and sintered at 350 °C before being subjected to dyeing. A comprehensive study was made on the mechanistic aspects of the EPD process. The dye-sensitized solar cell (DSSC) using the thus formed TiO2 film rendered a power conversion efficiency (Eff.) of 6.5%. Effects of various compression pressures on the photovoltaic parameters and on other characteristic parameters of the pertinent DSSCs are studied. Electrochemical impedance spectroscopy (EIS) is applied for the first time, using a novel equivalent model, to study the impedance behavior of the DSSC with this type of TiO2 film. We also obtain characteristic parameters of the TiO2 photoanode by using EIS. The coordination number of the TiO2 film, and the ratio of charge transfer resistances of electron recombination and electron transport are also obtained and analyzed. Moreover, we employ a multilayer approach and increase the film thickness to prepare TiO2 films with the same coordination number and porosity; DSSCs using such TiO2 films obtained from P90 and P25 rendered efficiencies of 6.5% and 5.24%, respectively. Scanning electron microscopy (SEM) micrographs are obtained to characterize the TiO2 films formed by the EPD technique and laser-induced transient technique is used to estimate the electron lifetime in the TiO2 films.