Novel 1,3,4-oxadiazole derivatives as efficient sensitizers for dye-sensitized solar cells: A combined experimental and computational study

We have synthesized and characterized donor-pi-spacer-acceptor type molecules in which 1,3,4-oxadiazoles are pi-spacers, triphenylamines are the donors and cyanoacetic acid are the acceptors for use as sensitizers in dye-sensitized solar cells (DSSCs). Detailed absorption, emission, electrochemical, photoelectrochemical and computational studies have been carried out on five novel derivatives. The dyes have an absorption range of 377-388 nm, and an emission in the range of 494-540 nm. There is a large charge transfer from the donor side to the acceptor side on excitation. The propeller shape of the triphenylamine and the bulky substituents on it help in reducing the dye-aggregation on TiO2 surface. The dyes exhibited good overall conversion efficiency (2.79-3.21%). Plane wave calculations indicate that the dye has a reasonably strong binding to the TiO2 surface and the generated DOS picture shows an overlap of the molecular orbitals of the dye and the TiO2 bands. We conclude that the dyes have a promising role as sensitizers in DSSC. (C) 2011 Elsevier B.V. All rights reserved.