Organic dyes incorporating the cyclopentadithiophene moiety for efficient dye-sensitized solar cells

Three triarylamine organic dyes (XS28–30) containing a cyclopentadithiophene unit as the conjugated bridge have been designed and synthesized for a potential application in dye-sensitized solar cells (DSSCs). Their absorption spectra, electrochemical and photovoltaic properties have been investigated. The incorporation of ethyl-substituted cyclopentadithiophene is highly beneficial to light-harvesting and preventing close π–π aggregation, thus favorably generating high efficiency. For a typical device, a solar energy conversion efficiency (η) of 5.8% based on XS29 was achieved under simulated AM 1.5 solar irradiation (100 mW cm−2) with a short-circuit photocurrent density (JSC) of 14.4 mA cm−2, an open-circuit voltage (VOC) of 601 mV, and a fill factor (ff) of 0.68. These results suggest that the functionalized cyclopentadithiophene unit is a promising candidate for DSSCs.

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► Three organic dyes were designed and synthesized for dye-sensitized solar cells.
► Cyclopentadithiophene moieties acted as the conjugated bridge.
► High photocurrent were achieved based on the three dyes without any conadsorbent.