Photoactive Polythiophene: Titania hybrids with excellent miscibility for use in polymer photovoltaic cells

A series of poly{(3-hexylthiophene)-co-[3-(6-hydroxyhexyl)thiophene]}:titania (P3HT-OH:TiO2) hybrids were synthesized via the in situ polycondensation of titanium (IV) n-butoxide in the presence of P3HT-OH. Introducing a hydroxyl moiety onto the side-chain of poly(3-hexylthiophene) (P3HT) significantly promotes the polymer-titania interaction, resulting in the formation of homogeneous hybrid colloids. The UV-vis spectra of P3HT-OH:TiO2 films demonstrate that TiO2 markedly affects the stacking structure and the chain conformation of P3HT-OH. The maximum absorption wavelength of these hybrid materials can be tailor-made by merely varying the weight percentage of TiO2. Moreover, -OH:TiO2 can be further utilized as an efficient comP3HT patibilizer in preparing photoactive P3HT:P3HT-OH:TiO2 films with excellent miscibility. The photovoltaic cell based on such a hybrid exhibited a 2.4-fold higher value of power-conversion efficiency compared to the cell based on P3HT:TiO2.