Photoconductivity on nanostructured sol-gel thin films with silver nanoparticles

2d-hexagonal nanostructured sol-gel thin films were prepared by dip-coating method. A neutral surfactant Brij58 was used as template to produced channels into the film. The structure was identified by X-ray diffraction and TEM. Silver nanoparticles were obtained by spontaneous reduction process of Ag ⁺ ions to Ag ⁰ at room temperature. A broad band located at 430 nm was detected by optical absorption; it corresponds to the surface plasmon. Photoconductivity studies were performed on films with ions and with silver nanoparticles to characterize their mechanisms of charge transport in the darkness and under illumination at 420 and 633 nm wavelengths. Straight lines showing an ohmic behavior fit the experimental data. Films without colloids possess normal photoconductivity behavior. But films with colloids present an abnormal response. Transport parameters were calculated. The films with silver nanoparticles exhibit a photovoltaic effect stronger than the films without nanoparticles, except to high concentrations. A theoretical model is proposed to predict these processes as function of the silver concentration.