Sol-gel derived nanoporous TiO2 films with the addition of polymer

Using sol-gel method, we prepared nano-structured and/or porous titania coatings on Si substrates by a mixture of chemically modified titanium tetraisopropoxide (TTIP) chelated with ethanol and polyethylene glycol (PEG). It was found that introducing PEG into the sol-gel process could trim the morphology and microstructure of TiO₂ film. By controlling PEG/TTIP concentration ratio, solution process, and thermal treatment, we can obtain a network structure of amorphous TiO₂ film even at thermal temperature lower than 120°C. After 500°C thermal treatment, the TiO₂ film structure changed from amorphous to anatase phase but also retain its nanoporous structure. Field emission scanning electron microscope (FE-SEM) image of our samples indicated that the TiO₂ film exhibited two kinds of nanopores with pore sizes within 100-200 nm and 30-50 nm. Based on these results, the sol-gel derived nanoporous TiO₂ Film is considered to have potential for solar cell application.