Conjugated polymers with pendant ruthenium dyes for photovoltaic applications

Abstract

Different conjugated polymers attached with ruthenium terpyridine trithiocyanato complexes were synthesized. The conjugaed main chains were based on poly(phenylenevinylene), poly(phenylenethiophene), and poly(fluorenethiophene). Introduction of these ruthenium dye molecules greatly enhance the optical absorption of these polymers in the visible region, spanning from 400 to 700 nm. The optical absorption in these polymers mainly resulted from two electronic transitions: the π-π* transition of the conjugated polymer and the d-π* metal-to-ligand charge transfer transition in the ruthenium complex. The hole and electron carrier mobilities of these polymers are in the order of 10-4 and 10-8 cm2/Vs, respectively. The polymers are soluble in DMF due to the presence of ionic complexes, and can be fabricated into thin film by spin coating process. Simple heterojunction devices ITO/polymer/fullerene/Al were fabricated and the power conversion efficiencies were in the range between 0.08 to 0.5 % under simulated solar light (AM1.5) illumination.