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 pi-pi aggregation, thus favorably generating high efficiency. For a typical device, a solar energy conversion efficiency (eta) 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 (J(SC)) of 14.4 mA cm(-2), an open-circuit voltage (V-OC) 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. (C) 2011 Elsevier Ltd. All rights reserved.