Ultrathin films of tetrasulfonated copper phthalocyanine-capped titanium dioxide nanoparticles: fabrication, characterization, and photovoltaic effect.

Tetrasulfonated copper phthalocyanine (CuTsPc)-capped TiO2 nanoparticle ultrathin films were fabricated by a layer-by-layer (LBL) self-assembly technique. Alternating bilayer structures were formed by consecutive adsorption of CuTsPc-capped TiO2 nanoparticles with poly(diallyldimethylammonium chloride). Optical and electrical measurements were carried out to characterize the CuTsPc-capped TiO2 nanoparticle ultrathin films. Optical measurements revealed uniform deposition. The surface morphology of such bilayer films showed a granular morphology similar to other classes of LBL films. Electrical measurements revealed an abnormal phenomenon under white light illumination. Electrochemical and photoelectrochemical measurements on such a bilayer system were carried out to elucidate the electron transport processes and the photovoltaic effect.