Improving energy transfer efficiency of dye-sensitized solar cell by fine tuning of dye planarity. (15th July 2019)

• Record Type: Journal Article
• Authors: Song, Xinkai; Yang, Xichuan; Wang, Haoxin; An, Jincheng; Yu, Ze; Wang, Xiuna; Hagfeldt, Anders; Sun, Licheng
• Is Part Of: Solar energy. Volume 187(2019)
• Page Start: 274
• Page End: 280
• Publication Date: 2019-07-15
• Subjects: Dihydroindolocarbazole sensitizers -- Dye-sensitized solar cells -- Sensitizer planarity; Solar energy -- Periodicals; Solar engines -- Periodicals; 621.47
• DOI: 10.1016/j.solener.2019.05.053
• Languages: English
• ISSNs: 0038-092X

Abstract

Graphical abstract: Slight modification by introduction of thienyl : Two new metal-free sensitizers with 5, 11-dihydroindolo[3, 2- b ]carbazole derivatives as electron-donating group were synthesized. Introduction of thienyl group improved the planarity of the dye molecule, broadened the absorption spectrum, resulting in a much higher power conversion efficiency. Highlights: Slight modification between push and pull units produced remarkable differences in device performance. The relationship between dye planarity and the photovoltaic performance of the DSC. SK202-based devices can achieve excellent efficiencies over 10% with two different redox couple. Abstract: Two push–pull metal-free sensitizers with 5, 11-dihydroindolo[3, 2- b ]carbazole derivatives as electron-donating groups and 4-(benzo[ c ][1, 2, 5]thiadiazol-4-ylethynyl)benzoic acid (BTZ) as electron-withdrawing unit, denoted bySK201 andSK202, were synthesized and used for fabrication of dye-sensitized solar cells (DSSCs).SK202 contains a thienyl group between the donor and acceptor, whereas inSK201 the donor and acceptor are connected directly by a single bond. Introduction of a thienyl group improved the planarity of the dye molecule, broadened the absorption spectrum, enhanced the molar extinction coefficient, increased the dye loading on TiO2, and accelerated interface electron transfer on TiO2 . This fine tuning of dye structure improved the performances of DSSCs based onSK202 sensitizers and gave a power conversion efficiency (PCE) of 11.0% ( J sc 16.5 mA cm −2, V oc 932 mV, and fill factor 71.7%), compared with that of 7.2% forSK201, under standard AM1.5G solar irradiation (100 mW cm −2 ) with a Co(II/III) complex based redox couple.