Composite films of carbon black nanoparticles and sulfonated-polythiophene as flexible counter electrodes for dye-sensitized solar cells

• Published in: Journal of power sources 2016-01, Vol.302, p.155-163
• Main Authors: Li, Chun-Ting, Lee, Chi-Ta, Li, Sie-Rong, Lee, Chuan-Pei, Chiu, I-Ting, Vittal, R., Wu, Nae-Lih, Sun, Shih-Sheng, Ho, Kuo-Chuan
• Format: Article
• Language: English
• Subjects: Carbon black; Counter electrode; Dye-sensitized solar cells; Flexible; Sulfonated-polythiophene; Titanium foil
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2015.10.028

A composite film based on carbon black nanoparticles and sulfonated-poly(thiophene-3-[2-(2-methoxyethoxy)ethoxy]-2,5-diyl) (CB-NPs/s-PT) is formed on a flexible titanium foil for the use as the electro-catalytic counter electrode (CE) of dye-sensitized solar cells (DSSCs). The CB-NPs provide the large amount of electro-catalytic active sites for the composite film, and the s-PT polymer serves as a conductive binder to enhance the inter-particle linkage among CB-NPs and to improve the adhesion between the composite film and the flexible substrate. The flexible CB-NPs/s-PT composite film is designed to possess good electro-catalytic ability for I−/I3− redox couple by providing large active sites and rapid reduction kinetic rate constant of I3−. The cell with a CB-NPs/s-PT CE exhibits a good cell efficiency (η) of 9.02 ± 0.01% at 100 mW cm−2, while the cell with a platinum CE shows an η of only 8.36 ± 0.02% under the same conditions. At weak light illuminations (20–80 mW cm−2), a DSSC with CB-NPs/s-PT CE still exhibits η's of 7.20 ± 0.04–9.08 ± 0.02%. The low-cost CB-NPs/s-PT CE not only renders high cell efficiency to its DSSC but also shows a great potential to replace the expensive platinum; moreover it is suitable for large-scale production or for indoor applications. [Display omitted] •Carbon black/sulfonated-polythiophene (CB-NPs/s-PT) worked as counter electrodes.•Water-soluble s-PT conductive binder was first used in dye-sensitized solar cells.•Flexible CB-NPs/s-PT film gave a good cell efficiency (η) of 9.02% at 100 mW cm−2.•At weak light illuminations, a cell with CB-NPs/s-PT still exhibited good η's.•Low-cost CB-NPs/s-PT gave great potential to replace Pt and for indoor devices.