Polyaniline–titania solid electrolyte for new generation photovoltaic single-layer devices

► Strong interaction between polyaniline and TiO2 and the formation of a core/shell structure. ► Enhancement of the absorption of TiO2 in the visible range. ► Diode-like behavior with low polyaniline content. ► Single layer photovoltaic device based on solid polyaniline–TiO2 composite. In this study, in situ chemical oxidative polymerization of very low quantities of aniline doped with HCl using ammonium persulfate inside an aqueous solution of 10wt.% of titanium dioxide was used to prepare a novel photovoltaic paint. Photoelectrical properties of the composite have been observed and the operating principle of the photovoltaic device is presented. We report an enhancement of the absorption of TiO2 powder in the visible range due to the sensitization by conductive polyaniline. Under illumination an open circuit voltage of 593mV and a short circuit current density of 0.502Am−2 were recorded. The surface conductivity of PANI–TiO2 pellets is measured using the four-point probe technique. The percolation theory together with variable range hopping explained the behavior of the surface conductivity of the composites. Morphological analysis using Transmission Electron Microscope showed the core/shell structure of the composites and energy dispersive X-ray showed the homogeneity of the composite. Fourier transform infrared spectroscopy confirmed the chemical adsorption of polyaniline at the surface of TiO2. UV–visible spectroscopy showed a shift of the polaron energy inside the polyaniline energy gap. The proposed morphology is showed to be responsible for the photoactivity of the composite.