Donor-acceptor dyes incorporating a stable dibenzosilole π-conjugated spacer for dye-sensitized solar cells

Md Akhtaruzzaman, Yohei Seya, Naoki Asao, Ashraful Islam, Eunsang Kwon, Ahmed El-Shafei, Liyuan Han, Yoshinori Yamamoto

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)


Four novel organic dyes including three based on dibenzosilole (YS01-03) and one based on fluorene (YS04) were synthesized, and their photophysical properties and dye-sensitized solar cell (DSC) performances were characterized. The silicon-containing dibenzosilole-based dyes (YS01-03) were superior to the carbon analogue fluorene-based dye YS04 in incident-photon-to-current conversion efficiency (IPCE), and total solar-to-electric conversion efficiency (η), with YS03, which has the bulkiest and most branched electron donor group, achieving the highest η of 5.07% compared to 2.88% of YS04. To better understand how silicon influences the excited state oxidation potentials (S +/*) and absorption maxima (λ max), the equilibrium molecular geometries of dyes YS01-04 were calculated using density functional theory (DFT) utilizing B3LYP energy functional and DGDZVP basis set. It was shown that the torsion angles (1 and 2) across the biphenyl linkages of dyes containing silicon (YS01-03) were less twisted than that of the silicon-free dye (YS04), which enhanced the π-π* overlap, and that translated into photocurrent enhancements in the silicon-containing dyes YS01-03. Moreover, the vertical electronic excitations and S +/* of dyes YS01-04 were studied using different long-range corrected time-dependent DFT methods, including CAM-B3LYP, LC-BLYP, WB97XD, and LC-wPBE at the basis set level DGDZVP. Excellent agreement between the calculated, using CAM-B3LYP/DGDZVP, and experimental results was found.

Original languageEnglish
Pages (from-to)10771-10778
Number of pages8
JournalJournal of Materials Chemistry
Issue number21
Publication statusPublished - 2012 Jun 7


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