Synthesizing porous anti-reflection and self-cleaning coatings as a cover for the glass of solar cells

Nowadays the use of photovoltaic systems has been increasingly common. These systems can be installed everywhere such as rooftops, deserts and outdoors in which different particles such as dust can deposit on their surface glass. These particles will limit the photons of the incident light to reach the inner layers of the solar cells which are responsible for energy conversion and as a result the efficiency of these panels will be reduced [1]. Also, the surface of the solar cells, without a cover layer, reflects back a considerable portion of the incident light which reduces the output of these devices (~30%). The idea of using a coating over the glass arises from this loss [2]. For solving these problems the application of self-cleaning antireflection coatings (ARC) on the cover glass of the solar panel is proposed and developed during the recent years. These coatings may be hydrophile or hydrophobe. Both of these coatings bring about the self-cleaning property which eliminates the need for cleaning the glass cover of the solar panels [3].In this study TiO2-based, TiO2-free and SiO2-based photocatalysts were synthesized and applied to solve the above-mentioned problems simultaneously. The aim was to trap the light by using the antireflection materials and imposing the self-cleaning effect with applying compounds with photocatalytic activity. The catalysts were prepared through sol-gel synthesis method and were coated on the glass slides using the dip coating method at different withdrawal speeds. The thickness of the deposited layer varied at different withdrawal rates. The catalysts were deposited on the slides in μm-thickness. Then the transmittance of the coatings was checked using WPA Spectrawave S1200 and S1200T Visible Spectrophotometer, also their self-cleaning capability was tested and compared to find the best ARC.