A Novel Tetrathiafulvalene- (TTF-) Fused Poly(aryleneethynylene) with an Acceptor Main Chain and Donor Side Chains: Intramolecular Charge Transfer (CT), Stacking Structure, and Photovoltaic Property

A novel tetrathiafulvalene- (TTF-) fused poly(aryleneethynylene) with an acceptor main chain and donor side chains has been prepared and characterized. The EPR and UV–vis spectra show that there exists intramolecular charge transfer (CT) between the electron-rich TTF side chains and the electron-deficient main chain. The band gaps deduced from UV–vis absorption spectroscopy and electrochemical studies are 1.78 and 1.84 eV, respectively. Powder X-ray diffraction analysis indicate that the polymer forms a self-assembled π-stacking structure and the polymer takes an interdigitation packing mode. Polymer solar cell has been fabricated with the blend of the TTF-fused polymer and C60 as the photosensitive layer. The power conversion efficiency is 0.25% under AM 1.5 simulated sun light (100 mW/cm2). The intramolecular charge transfer was also confirmed by the chemical oxidation of the polymer with Fe(bpy)3(PF6)3 (bpy = 2,2′-bipyridine).