Functional π-conjugated tetrathiafulvalene decorated with benzothiadiazole organic sensitizers for dye sensitized solar cells

Abstract

We report a series of extended-π conjugated tetrathiafulvalene (exTTF) based sensitizers for Dye Sensitized Solar Cell (DSSC) application. In our approach, we have used exTTF as a donor, benzo-thiadiazole-thiophene as a π-bridge and either cyanoacrylic acid (G7 and G8) or rhodanine-3-acetic acid as an acceptor (G9). G7, G8 and G9 sensitizers are characterized by various spectroscopic techniques. When adsorbed on nanocrystalline TiO2, the onset of the absorption of these sensitizers was in the 550-700 nm region. DFT studies indicate that the HOMO is delocalized over the anthracene unit mainly and marginally over the π-spacer, whereas the LUMO is delocalized over the π-spacer and anchoring group in all these three sensitizers. Among the fabricated DSSCs with these sensitizers, the G9 based DSSC has shown the best power conversion efficiency of 6.0%.