Molecular engineering of ruthenium-diacetylide organometallic complexes towards efficient green dye for DSSC

Three new dyes encompassing the organometallic [Ru(dppe)2] (dppe = 1,2-bis(diphenylphosphino)ethane) fragment were designed and prepared for application in dye-sensitized solar cells. Introduction of the strong electron-withdrawing benzothiadiazole (BTD) unit as an additional acceptor in the attracting ligand led to original D−[M]−A−π−A′ architectures. In particular the use of a thienyl-BTD motif led to a narrow bandgap sensitizer with deep-green coloration. The dye afforded 5.2% power conversion efficiency in TiO2-based DSSC device in the presence of the iodine/iodide couple as redox mediator. A joint experimental and theoretical study of the new dyes is reported.