Synthesis of Conjugated Polymers Containing Terpyridine−Ruthenium Complexes: Photovoltaic Applications

We report the synthesis of ( E )-3-(4-bromo-2,5-dioctylphenyl)-2-(4-vinylphenyl)acrylonitrile ( 5 ). We further report the synthesis of conjugated polymer materials by palladium-catalyzed Heck coupling polymerization of 5 and 4-bromo-2,5-dioctyl-4‘-vinylstilbene ( 3 ) in the presence of 4‘-(4-bromophenyl)-2,2‘:6‘,2‘ ‘-terpyridine ( 8 ), giving poly(dioctylstilbenevinylene)s terminated by a terpyridine moiety. Their assembly using ruthenium complexation led to coordination homopolymers and copolymer with tetrafluoroborate counterions. The materials were characterized using SEC, MALDI, NMR, UV−vis, and fluorescence spectroscopy. The polymers were found to transfer energy to the complexes as seen through the complexes ability to quench fluorescence. The coordination polymers were applied to photovoltaics, and two types of devices were prepared: polymer solar cells obtained by spin-coating of the coordination polymer solution onto PEDOT:PSS-covered ITO substrates and dye-sensitized solar cells obtained by absorption on TiO 2 nanocrystalline films using two different electrolytes. Dye-sensitized solar cells (DSSCs) prepared using the copolymer 15 gave the best results with efficiencies reaching ∼0.1% with the redox couple Co II,III as electrolyte, whereas the coordination homopolymer 13 gave the best results as organic solar cells with very low efficiency (<0.01%) under illumination at 1000 W/m 2 AM1.5.