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Pt- and TCO-Free Flexible Cathode for DSSC from Highly Conducting and Flexible PEDOT Paper Prepared via in Situ Interfacial Polymerization

Anothumakkool, Bihag, Agrawal, Ishita, Bhange, Siddheshwar N., Soni, Roby, Game, Onkar, Ogale, Satishchandra B., Kurungot, Sreekumar
ACS applied materials 2016 v.8 no.1 pp. 553-562
catalytic activity, cathodes, cellulose, coatings, electrochemistry, glass, oxides, paper, photovoltaic cells, polymerization
Here, we report the preparation of a flexible, free-standing, Pt- and TCO-free counter electrode in dye-sensitized solar cell (DSSC)-derived from polyethylenedioxythiophene (PEDOT)-impregnated cellulose paper. The synthetic strategy of making the thin flexible PEDOT paper is simple and scalable, which can be achieved via in situ polymerization all through a roll coating technique. The very low sheet resistance (4 Ω/□) obtained from a film of 40 μm thick PEDOT paper (PEDOT-p-5) is found to be superior to the conventional fluorine-doped tin oxide (FTO) substrate. The high conductivity (357 S/cm) displayed by PEDOT-p-5 is observed to be stable under ambient conditions as well as flexible and bending conditions. With all of these features in place, we could develop an efficient Pt- and TCO-free flexible counter electrode from PEDOT-p-5 for DSSC applications. The catalytic activity toward the tri-iodide reduction of the flexible electrode is analyzed by adopting various electrochemical methodologies. PEDOT-p-5 is found to display higher exchange current density (7.12 mA/cm²) and low charge transfer resistance (4.6 Ω) compared to the benchmark Pt-coated FTO glass (2.40 mA/cm² and 9.4 Ω, respectively). Further, a DSSC fabricated using PEDOT-p-5 as the counter electrode displays a comparable efficiency of 6.1% relative to 6.9% delivered by a system based on Pt/FTO as the counter electrode.