Preparation of TiO2 thin films on glass surfaces with self-cleaning characteristics for solar concentrators

High concentration photovoltaic (HCPV) systems improve their long-term stability in terms of sunlight concentration by using silicone-on-glass (SOG) composite optic lenses with glasses. Due to dust pollution, reflectance of the concentrator glasses significantly decreases the output power efficiency of a solar power system. Titanium dioxide (TiO2) films are known for their hydrophilic and photocatalytic characteristics. This study investigates the effects of introducing third elements in a-TiO2 films by implantation, to enhance the photocatalytic and hydrophilicity properties, as well as widen the wavelength sensitization range. TiO2-based hydrophilic and photocatalytic films on glass for self-cleaning purposes were prepared. The implant elements are Fe, Cr, and V. The samples are prepared by a hybrid system consisting of physical vapor deposition (PVD) and metal plasma ion implantation (MPII). High quality TiO2 films are first fabricated by r.f. magnetron sputtering system, followed by metal plasma ion implantation of Fe. Experimental results indicate that the hybrid processing method significantly increases the activation and sunlight absorption rate of TiO2 thin films with the addition of third elements. Moreover, the proposed TiO2–Fe thin film exhibits superior hydrophilicity properties with a contact angle of 9.95° and reduces the optical bandgap to 3.33 eV.