Synthesis And Characterization Of Conjugated Polymers Containing Ru(Ⅱ) Complexes For Photovoltaic Aplications

Aiming to obtain photovoltaic materials with excellent performance, two conjugated polymers PBT and PBP with bipyridine ligands in the main chain, and another two polymers PCC and PCP with pendant 2-(2-pyridyl)benzimidazole(PBI) ligands were synthesized starting from corresponding monomer design based on the consideration of combining metal sensitizers and semiconductive conjugated polymers. Thereafter, four related ruthenium-containing polymers, PBTRu, PBPRu, PCPRu and PCCRu, were obtained through the coordination of the corresponding ligand polymer with ruthenium complex sensitizers. These polymers were characterized respectively by IR, GPC, TG and UV-vis to make clear their structural information, thermal stability and optical absorption properties.Polymers PBT and PBP were synthesized through Horner-Wadsworth-Emmons polymerization, both of which together with their Ru-complexes, PBTRu and PBPRu, possessed good solubility in common organic solvents ensuring convenient film preparation through solution casting. UV-vis spectra revealed that the red shift of absorptions is obvious upon the introduction of Ru-complexes, and absorptions derived from metal-ligand charge transfer in polymers PBTRu and PBPRu were observed. Therefore, the conjugated polymers with Ru-complexes, PBTRu and PBPRu, might be good candidate as photoactive materials in the fabrication of photovoltaic cells with high performance.The synthesis of polymers PCP and PCC with pandent PBI moieties was performed through Wittig polymerization and Knoevenagel polymerization, respectively, in which the conjugated polymer main chain is linked with the metal complex through a flexible alkylene spacer. Such a molecular topology could not only ensure the perfection of conjugation effect over the polymer backbone, but also enhance the light absorption ability of the entire materials in combining with the Ru-complex sensitizer. UV-vis spectra showed that the edge absoption of PCPRu and PCCRu reaches near infrared region and new absorptions peaked at 587.Onm and 586.5nm were observed, respectively. Furthermore, due to the enhanced intermolecular interaction derived from the cyano group, PCC is more thermally stable than PCP as proved by TG...