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 pi-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 C-60 as the photosensitive layer. The power conversion efficiency is 0.25% under AM 1.5 simulated sun light (100 mW/cm(2)). The intramolecular charge transfer was also confirmed by the chemical oxidation of the polymer with Fe(bpy)(3)(PF6)(3) (bpy = 2,2'-bipyridine).