Phenothiazine derivatives as organic sensitizers for highly efficient dye-sensitized solar cells

Chih Jen Yang, Yuan Jay Chang, Motonori Watanabe, Yung Son Hon, Tahsin J. Chow

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Abstract

A series of organic dyes containing a phenothiazine central unit were synthesized and were used effectively in the fabrication of dye-sensitized solar cells (DSSCs). A cyanoacrylate moiety was added at the C(3) position of the phenothiazine as an electron acceptor, and a triarylamine moiety was attached at the C(7) position as an electron donor. The DSSCs made with these dyes displayed remarkable quantum efficiency, ranging from 4.2-6.2% under an AM 1.5 solar condition (100 mW cm -2). A variety of substituents, i.e., methyl, hexyl and triphenylamino groups, were added at the N(10) of phenothiazine in order to optimize the incident photon-to-current conversion efficiency. Along the main chromophore a thiophenylene group was inserted at different positions to examine its influence on the properties of devices. The best performance was found in compound NSPt-C6, in which a hexyl group was attached at the N(10) of phenothiazine and a thiophenylene at the C(7) position. It displayed a short-circuit current (J sc) of 14.42 mA cm -2, an open-circuit voltage (V oc) of 0.69 V, and a fill factor (ff) of 0.63, corresponding to an overall conversion efficiency of 6.22%. Their photophysical properties were analyzed with the aid of a time-dependent density functional theory (TDDFT) model with the B3LYP functional. Their photovoltaic behavior was further elucidated by the electrochemical impedance spectroscopy.

Original languageEnglish
Pages (from-to)4040-4049
Number of pages10
JournalJournal of Materials Chemistry
Volume22
Issue number9
DOIs
Publication statusPublished - Mar 7 2012
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Materials Chemistry

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