Thioalkyl-Functionalized Bithiophene (SBT)-Based Organic Sensitizers for High-Performance Dye-Sensitized Solar Cells

Yamuna Ezhumalai, Fang Sian Lin, Miao Syuan Fan, Kumaresan Prabakaran, Jen Shyang Ni, Yi Ching Wu, Gene Hsiang Lee, Ming Chou Chen, Kuo Chuan Ho

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26 Scopus citations


A series of 3,3′-dithioalkyl-2,2′-bithiophene (SBT)-based organic chromophores were designed and developed for the use in dye-sensitized solar cells (DSSCs). By appropriate structural modification of the SBT Ï-linkers with different alkyl chains and conjugated thiophene units, chromophore aggregation and interfacial charge recombination could be suppressed to a remarkable degree. Single-crystal and optical/electrochemical data clearly show that the SBT core is nearly planar with the torsional angle <1°, likely via S(alkyl)···S(thiophene) intramolecular locks. Therefore, this highly Ï-conjugated unit should enhance panchromatic light-harvesting and prove to be an excellent core for organic dye. For comparison, the 3,3′-dialkyl-2,2′-bithiophene (BT)-based dye was also prepared. Under 1 sun (100 mW cm-2) illumination, an optimized SBT-6 dye-sensitized cell indicates a short-circuit current density (JSC) of 17.21 mA cm-2, an open-circuit voltage (VOC) of 0.78 V, and a fill factor (FF) of 0.71, corresponding to a power conversion efficiency (Ε) of 9.47%, which is nearly two times higher than that of alkylated bithiophene (BT)-based chromophores. Finally, the proposed sensitizer SBT-6 exhibited an excellent Ε of 23.57% under the T5 fluorescent illumination of 6000 lux. To the best of our knowledge, this is the highest power conversion efficiencies (PCE) value reported to date among the studied thiophene or bithiophene-based chromophores.

Original languageEnglish
Pages (from-to)15071-15079
Number of pages9
JournalACS Applied Materials and Interfaces
Issue number13
StatePublished - 1 Apr 2020


  • 2′-bithiophene
  • 3
  • 3′-dithioalkyl-2
  • aggregation
  • panchromatic light-harvesting
  • S(alkyl)···S(thiophene) intramolecular locks
  • T5 fluorescent illumination


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