Low-temperature flexible Ti/TiO sub(2) photoanode for dye-sensitized solar cells with binder-free TiO sub(2) paste

• Published in: Progress in photovoltaics 2012-03, Vol.20 (2), p.181-190
• Main Authors: Lin, Lu-Yin, Lee, Chuan-Pei, Tsai, Keng-Wei, Yeh, Min-Hsin, Chen, Chia-Yuan, Vittal, R, Wu, Chun-Guey, Ho, Kuo-Chuan
• Format: Article
• Language: English
• Subjects: Annealing; Dyes; Pastes; Photovoltaic cells; Scanning electron microscopy; Solar cells; Titanium; Titanium dioxide
• ISSN: 1062-7995; 1099-159X
• DOI: 10.1002/pip.1116

An energy-economical dye-sensitized solar cell (DSSC) with highly flexible Ti/TiO sub(2) photoanode was developed through a low-temperature process, using a binder-free TiO sub(2) paste. Ti foils, coated with the binder-free TiO sub(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 sub(2) network. DSSCs with binder-free TiO sub(2) films annealed at 450, 350, 250 and 120 degree C show solar-to-electricity conversion efficiencies ( eta ) 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 degree C; this observation demonstrates the benefits of a binder-free TiO sub(2) paste for the fabrication of energy-fugal DSSCs. On the other hand, when organic binder was used in the TiO sub(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 sub(2) films. Electrochemical impedance spectroscopic (EIS) analysis shows that the lower the annealing temperature of the TiO sub(2) coated Ti foil, the larger the charge transfer resistance at the TiO sub(2)/dye/electrolyte interface (R sub(ct2)). Copyright copyright 2011 John Wiley & Sons, Ltd. Flexible dye-sensitized solar cells (DSSCs) with binder-free TiO sub(2) films annealed at 450, 350, 250 and 120 degree C show cell efficiencies of 4.33, 4.34, 3.72, and 3.40%, respectively, which are comparable to that of 4.56% obtained by using a paste with binder (450 degree C); this observation demonstrates the benefits of a binder-free TiO sub(2) paste for the fabrication of energy-fugal DSSCs. Laser-induced photo-voltage transient technique is used to estimate the electron lifetime in various Ti/TiO sub(2) films.