Low‐temperature flexible Ti/TiO 2 photoanode for dye‐sensitized solar cells with binder‐free TiO 2 paste

An energy‐economical dye‐sensitized solar cell (DSSC) with highly flexible Ti/TiO 2 photoanode was developed through a low‐temperature process, using a binder‐free TiO 2 paste. Ti foils, coated with the binder‐free TiO 2 films were annealed at various temperature. Scanning electron microscopic (SEM) images of the films show uniform, mesoporous and crack‐free surface morphologies as well as interpenetrated TiO 2 network. DSSCs with binder‐free TiO 2 films annealed at 450, 350, 250 and 120°C show solar‐to‐electricity conversion efficiencies ( η ) of 4.33, 4.34, 3.72 and 3.40%, respectively, which are comparable to the efficiency of 4.56% obtained by using a paste with binder and annealing it at 450°C; this observation demonstrates the benefits of a binder‐free TiO 2 paste for the fabrication of energy‐fugal DSSCs. On the other hand, when organic binder was used in the TiO 2 paste for film preparation, a drastic deterioration in the cell performance with decreasing annealing temperature is noticed. Laser‐induced photo‐voltage transient technique is used to estimate the electron lifetime in various Ti/TiO 2 films. Electrochemical impedance spectroscopic (EIS) analysis shows that the lower the annealing temperature of the TiO 2 coated Ti foil, the larger the charge transfer resistance at the TiO 2 /dye/electrolyte interface ( R ct2 ). Copyright © 2011 John Wiley & Sons, Ltd.