Characterization of vinyltriethoxysilanetetraethoxysilane- tetrabutoxytitanate hydrophobic solgel coating fo r photovoltaic panels

Abstract

Surfaces that simultaneously exhibit hydrophobicity, high contact angle and high transmission o f visible light are o f interest for many applications such as optical devices, photovoltaic (PV) panels and self-cleaning windows. The fabrication o f such surfaces is challenging due to the complex preparation using various compositions and thermal treatm ent with the requirement o f a controlled environment. In this study, the main goal was to develop and characterize hydrophobic coating using sol-gel method in ambient condition suited for PV application. A solution was prepared using three different materials including vinyltriethoxysilane (VTES), tetraethoxysilane (TEOS) and tetrabutoxytitanate (TTBU) called VTT (VTES-TEOS-TTBU) sol as the organicinorganic hybrid sol. Then, this sol was applied onto glass substrates using spincoating method for laboratory-scale working samples. Coated samples were produced into two sets with different composition to obtain silica-titania sol using Post-addition o f W ater to Titanium Alkoxide (PWTA) and Chemically M odified Titanium Alkoxide (CMTA). The effects o f different com position were examined with respect to the contact angle, surface roughness, and transmittance. Besides, the VTT coating has also undergone different thermal treatments to study its hydrophobicity effect. Based on the results obtained, VTT sol still showed hydrophobic properties (CA>90°) even when fabricated under am bient condition. The increase o f temperature in the pre-bake and post-bake process increased the hydrophobicity o f VTT coating. Moreover, CMTA method showed better hydrophobicity compared to the PW TA method. The best sample obtained was the CM TA sample with the highest post-bake thermal treatment (150°C) which exhibited the highest contact angle (110.01°), surface roughness (0.452 nm) and transmission percentage (96% centered at 571 nm of wavelength). All coating samples were prepared in ambient condition with promising performance, eliminating the need for controlled condition based on previous research to suit the varied temperature and humidity for different coating preparation.