Detailed analysis and formation mechanism of superhydrophobic antireflective coatings with adjustable refractive index from trimethylsilanized silica nanoparticles

Abstract

This paper dealt with the fabrication of sol-gelderived organically modified silica (ormosil) films on glasses from trimethylsilanized silica nanoparticles (SNPs) using hexamethylisilazane (HMDS) as the modification agent. The prepared sols were suitable for large-area processing with ease of coating and being directly applicable without requiring any pre-or post-treatment. By a dipcoating process, these HMDS-treated sols gave antireflective (AR) coatings exhibiting precisely tunable refractive indices ranging from 1.19 to 1.12, in a range that is not accessible to nonporous inorganic materials. Films produced a fair AR effect consisting of more than a 6 % increase in optical transmittance. The particle surface modification with HMDS significantly improved the hydrophobicity of the coated film. According to the dynamic light scattering (DLS) method, the HMDS modification at the surface of the pure spherical SNPs enlarged the SNP size from 12.4 to 22.3 nm. The relationship between the microstructure of silica sols and the properties of films was investigated. Besides this, the effects of various factors on the morphology of sols and films were studied to propose a mechanism for the formation of the adjustable refractive index thin films. Graphical Abstract

Fabrication of a Porous Low Refractive Index Anti-Reflective Coating with High Transmittance by Using the Porogen of Laureth-5 Carboxylic Acid

“…In another work, an acid-catalyzed sol-gel technique was optimized to fabricate SiO 2 , which was then deposited on glass for sintering in a conventional furnace at temperatures ranging from 350 to 550 • C for 1 h. The prepared ARCs exhibited broadband anti-reflection properties across the spectral response range of multijunction solar cells. By fine-tuning the process in the visible light range, the coating achieved 6% anti-reflection [24]. In addition, researchers are also interested in fabricating materials with hierarchical porosity, which can optimize the preparation processes of porous ARCs [25,26].…”

Low-Temperature Preparation of Mechanically Robust and Contamination-Resistant Antireflective Coatings for Flexible Polymeric Glasses via Embedding of Silica Nanoparticles and HMDS Modification

“…To overcome the performance degradation of the sol–gel silica coatings, varieties of amphiphobic groups such as organosilane, − fluoroalkylsilane, − and polymers − have been introduced onto the SNP surface of the coatings to enable the coating to be contamination-resistant. Sun et al grafted fluoroalkylsilane on the surface of ordered cagelike mesoporous silica coatings (MSCs) so as to close the open pore entrance.…”

Sol–gel preparation of moisture-resistant antireflective coatings from novel hollow silica nanoparticles

“…One is to improve the hydrophobic nature of silica thin films because it is closely linked to the durability of the AR coating [13]. There have been many attempts to prepare silica AR coatings with improved hydrophobicity by the introduction of organic molecules or polymers bearing hydrophobic groups into the coatings [14][15][16][17][18][19][20]. However, in order to achieve satisfiable environmental resistance, these methods need to add large amounts of polymer or hydrophobic silane precursors to give the AR coatings enough hydrophobic groups.…”