Designing hydrophobic, anti-soiling coatings for solar module cover glass: degradation mechanisms to avoid

Abstract

In this paper, we identify the degradation mechanisms occurring with these coatings, in this way, we can identify more suitable coatings whose chemistry avoids these degradation pathways. Two such coating technologies used in other applications are perfluoropolyether (PFPE) and 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FAS-17). These polymeric hydrophobic coatings were deposited on soda–lime glass substrates and tested for 1000 hours in an accelerated UV exposure test and a damp heat test in a laboratory environment. After 1000 hours of UV exposure, the coatings experienced degradation with the PFPE coating degrading via β scission of the central ether bond whilst the FAS-17 underwent photo-oxidation at the C–Si bond. During damp heat testing the PFPE degraded by hydrolysis at the central ether bond whilst FAS-17 exhibited resistance to hydrolysis. The chemical mechanisms responsible for the degradation are identified. The objective is to discover alternative transparent hydrophobic materials that do not contain the same weaknesses in their chemical structure.