Transparent dust removal coatings for solar cell on mars and its Anti-dust mechanism

Abstract

Transparent hybrid coatings were prepared from methyltrimethoxysilane (MTMS) and colloidal silica nanoparticles (SiO2) by a sol-gel process. Influences of colloidal silica content and aging time on the surface morphology, surface composition, and the properties such as transparency, water contact angles (WCA), and pencil hardness, of the hybrid coatings were systematically investigated. Coatings with WCA as high as 110–120° and pencil hardness of 4–5 H could be achieved at appropriate colloidal silica content and aging time. The dust removal performance of the hybrid coatings was examined by vertical tilting of the dust-deposited coatings using volcanic ash as the standard dust. When the WCA was over about 100°, the hybrid coatings exhibited excellent dust removal performance under gravity, regardless of the quantity of the dust deposited. Oxygen plasma etching experiments and the dust removal tests in dry chamber indicated that the nanometer-scale surface roughness could endow the hybrid coatings with the good dust removal performance. The hydrophobic methyl groups can further enhance the dust removal performance. The hybrid coating with MTMS/SiO2 mass ratio of 1.3:1 was cast on the coverslips of the solar cell for Mars, and undergone two durability series tests, i.e. thermal shock/humidity series (THS) test and high-low temperature cycle/electron beam radiation/vacuum ultraviolet radiation series (HEVS) test. The anti-dust coverslips showed good durability in HEVS tests and dust removal percentage of 75.8% after HEVS test, implying its good service life on Mars.