Pyridazine-based copolymers with carbazole and their Rhenium complexes for solar cells

Many low band gap copolymers combining carbazole with electron-withdrawing moiety were reported. We designed and synthesized new electron-withdrawing comonomers, with bis-imine aromatic ligands (1,2-diazine) to exploit metal coordination with Re for lowering LUMO level and increasing absorption in visible region, namely phtalazine and thienopyrazine. The corresponding P1 and P2 copolymers were obtained in different conditions to assure the highest amount of alternated copolymer. Spectroscopic (NMR, IR, UV-Vis, PL) and electrochemical (CV) characterizations of P1, P2, ReP1 and ReP2, in solution and as film, were performed. NMR and MALDI-TOF analyses show a different enchainment in polymeric backbone due to the nature of electron-withdrawing unit, affecting electronic and thermal properties and solar cells efficiencies.