Effects of mesoscopic poly(3,4-ethylenedioxythiophene) films as counter electrodes for dye-sensitized solar cells

• Published in: Thin solid films 2010, Vol.518 (6), p.1716-1721
• Main Authors: Lee, Kun-Mu, Chiu, Wei-Hao, Wei, Hung-Yu, Hu, Chih-Wei, Suryanarayanan, Vembu, Hsieh, Weng-Feng, Ho, Kuo-Chuan
• Format: Article
• Language: English
• Subjects: Applied sciences; Carbon nanotubes; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Conducting polymer; Counter electrode; Cross-disciplinary physics: materials science; rheology; Deposition by sputtering; Dye-sensitized solar cells; Electrical properties of specific thin films; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Energy; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Natural energy; Photovoltaic conversion; Physics; Poly(3,4-ethylenedioxythiophene); Solar cells. Photoelectrochemical cells; Solar energy; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2009.11.058

Counter electrode coated with chemically polymerized poly(3,4-ethylenedioxythiophene) (PEDOT) in a dye-sensitized solar cell (DSSC) was studied. The surface morphology and the nature of I −/ I 3 − redox reaction based on PEDOT film were investigated using Atomic Force Microscopy and Cyclic Voltammetry, respectively. The performance of the DSSCs containing the PEDOT coated electrode was compared with sputtered-Pt electrode. We found that the root mean square roughness decreases and conductivity increases as the molar ratio of imidazole (Im)/EDOT in the PEDOT film increases. The DSSC containing the PEDOT coated on fluorine doped tin oxide glass with Im/EDOT molar ratio of 2.0, showed a conversion efficiency of 7.44% compared to that with sputtered-Pt electrode (7.77%). The high photocurrents were attributed to the large effective surface area of the electrode material resulting in good catalytic properties for I 3 − reduction. Therefore, the incorporation of a multi-walled carbon nanotube (MWCNT) in the PEDOT film, coated on various substrates was also investigated. The DSSC containing the PEDOT films with 0.6 wt.% of MWCNT on stainless steel as counter electrode had the best cell performance of 8.08% with short-circuit current density, open-circuit voltage and fill factor of 17.00 mA cm − 2, 720 mV and 0.66, respectively.