4H-pyranylidene organic dyes for dye-sensitized solar cells: Twisted structures towards enhanced power conversion efficiencies

Five sensitizers bearing a 4H-pyranylidene moiety have been synthesized. The incorporation of a thiophene ring (with different substituents in its position 5), in the exocyclic double bond of the previously reported SFO-346, leads to twisted structures of type 2D-π-A and D–(π–A)2 that minimize the π-π stacking of the dyes on the photoanode. Theoretical calculations confirm the tridimensional structure of the molecules. Moreover, the different...