Efficient Small Molecule Organic Dyes Containing Different Bridges in Donor Moieties for Dye-Sensitized Solar Cells

Abstract

Small molecule (molecular weight is around 500Da) organic dyes were synthesized and used as sensitizers for the dye-sensitized solar cells (DSSCs). The optical and electrochemical properties, theoretical studies and photovoltaic parameters of DSSCs baseed on these dyes were systematically investigated. In order to extend the conjugation extent, two extra phenyl units were attached to triphenylamine (TPA) units bridged with single bonds, double bonds or triple bonds, respectively. The DSSCs based on FWDS exhibited well performances: the short-circuit current density (Jsc) of 10.04, 10.91 and 9.12mAcm−2, respectively; the open circuit voltage (Voc) of 0.77, 0.75 and 0.78V, respectively; the power conversion efficiency (η) of 5.65%, 6.04% and 5.19%, respectively. Two extra phenyl units attached via double or triple bonds increase the planar nature of these molecules, increasing the loading amount, which ultimately can correlate into the received efficiency. The results indicated that it is an effective way to get efficient dyes by introducing extra phenyl rings into donor moiety especially adopting double bonds as the bridge. Finally, efficient DSSCs were achieved by using small molecule TPA-type dyes FWD1, FWD2 and FWD3 as the sensitizers.