Optical properties of poly(3-hexylthiophene) and interfacial charge transfer between poly(3-hexylthiophene) and titanium dioxide in composites

The optical properties of poly(3-hexylthiophene) (P3HT), in pristine form or with added anatase titanium dioxide (TiO2) nanoparticles have been investigated, and the interfacial charge transfer between P3HT and TiO2 have been studied by steady-state luminescence spectroscopy analysis. The photoluminescence results revealed that incorporation of TiO2 nanoparticles in concentrations up to 0.3 mM significantly enhanced the luminescence intensity of P3HT when exposing to light of energy higher than TiO2 bandgap. The observed variation suggested an energy transfer from TiO2 nanoparticles to P3HT. Meanwhile, when P3HT/TiO2 composites were exposed to light of energy below TiO2 bandgap, TiO2 nanoparticles gradually quench the fluorescence of P3HT, demonstrating the injection of excited electrons from lowest unoccupied molecular orbit of P3HT to the conduction band of TiO2.