Deposition and possible influence of a self-cleaning thin TiO2/SiO2 film on a photovoltaic module efficiency

Titanium dioxide as a semiconductor is present for quite some time in the history of solar cell, but not in the form of self-cleaning surfaces. TiO2-SiO2 nanostructured coatings used in environmental applications have proved to be good antifogging, self-cleaning and antimicrobial surfaces due to their photocatalytic properties and photoinduced superhydrophilicity. The main purpose of this research is to investigate whether there is an increase of efficiency of a photovoltaic cell by incorporating a self-cleaning coating on the photovoltaic module, assuming that its efficiency depends on the cleanliness of the surface. Structural and morphological characteristics of TiO2-SiO2 coatings, named UNG10-7C, were analysed by UV-vis and FT-IR spectroscopies, X-ray diffraction and scanning electron microscopy, whereas superhydrophilicity and photocatalytic activity were confirmed by water contact angle measurements and by monitoring the hydroxylation of terephthalic acid. The coating UNG10-7C was deposited on one of the two photovoltaic modules that were exposed to external conditions for 2 months and current-voltage characteristics were monitored. In such a short time, differences in the efficiency of modules were not evident. Nevertheless, it turned out that the coating itself does not reduce the light absorption in the silicon solar cell. (C) 2014 Elsevier B.V. All rights reserved.