Photo-induced electron transfer from a dithieno thiophene-based polymer to TiO2

A spectroscopical study of composites made with a new conjugated polymer, polydithienothiophene, and nanocrystalline TiO2 is carried out by optical absorption, photoluminescence and steady state photo-induced absorption spectroscopy. Sintered nanoporous TiO2 films have been stained by dipping the inorganic semiconductor films into dithienothiophene polymer solutions. The optical absorption spectra indicate that this polymer is well absorbed into nanoporous TiO2 films, showing a remarkable interaction with the inorganic semiconductor as compared to other alkyl substituted thiophene based conjugated polymers. The photoluminescence quenching and the steady state photo-induced absorption spectra evidence that TiO2 acts as an efficient electron acceptor toward the polymer in the excited state. These features indicate that this conjugated polymer is a promising material to develop new hybrid organic/inorganic photovoltaic cells.