Phenylethyne-Bridged Dyes for Dye-Sensitized Solar Cells

Four metal-free organic dyes (Dye-1, Dye-2, Dye-3, and Dye-4) comprising a triphenylamine moiety as the electron donor, a cyanoacrylic acid or carboxylic acid moiety as the electron acceptor and anchoring groups, and phenylethyne as the bridge were designed at the molecular level and synthesized for use in dye-sensitized solar cells (DSSCs). Their absorption spectra and electrochemical and photovoltaic properties were fully characterized, and the electron distribution with the different acceptors was calculated using density functional theory at the B3LYP/6-31G level. All of these dyes performed as sensitizers for the DSSC test, and the cyarioacrylic acid Dye-4 showed an overall conversion efficiency of 3.61% (J(sc) = 9.30 mA/cm(2), V-oc = 0.73 V, ff = 0.49) under AM 1.5 irradiation (100 mW/cm(2)), which reached 79% with respect to that of an N719-based device fabricated under similar conditions. Meanwhile, the photovoltaic performance data of these phenylethyne-bridged dyes showed a higher open circuit voltage (0.70-0.79 V).