Fabrication and photovoltaic properties of self-assembled sulfonated polyaniline/TiO₂ nanocomposite ultrathin films

Two kinds of TiO₂/sulfonated polyaniline (SPAn) nanocomposite ultrathin films were fabricated by layer-by-layer (LBL) self-assembly technique on various solid surfaces. One was fabricated with self-doped sulfonated polyaniline (SD-SPAn) and TiO₂ sol, and another was with externally (HCl)-doped sulfonated polyaniline (ED-SPAn) and TiCl₄. The linear growth of both the LBL films was proved by UV-vis spectroscopy. The ordered multilayer films were subsequently characterized by atomic force microscopy, cyclic voltammetry, and photoelectrochemical measurement. Their structure, electrochemical and photoelectrochemical properties were comparatively investigated. The morphology of ED-SPAn/TiO₂ LBL films is evener and smoother than that of SD-SPAn/TiO₂ LBL films. Two kinds of LBL films have different electrochemical behaviours, and ED-SPAn/TiO₂ LBL films show a stabler but slower photocurrent response than SD-SPAn/TiO₂ LBL films.