Designing Multifunctional Silica Coatings for Enhanced Broadband Antireflection and Microfiber Contamination Sensing

Abstract

Multifunctional silica coatings are usually applied as antireflective coatings on optoelectronic devices. We report a facile route to synthesize multifunctional silica nanomaterials by an acid/base two-step catalyzed sol–gel process. Due to the tunable porous microstructure of colloidal particles, we applied it as double-layer broadband antireflective coatings and expanded its application to enhance the sensitivity of contaminants sensors. Under the computer-aided design, the optimized double-layer mixture coatings possess excellent broadband antireflective performance in the visible regions as well as high environmental durability. The maximum transmittance of double-layer coatings reaches 99.87% at 591 nm; the average transmittance surpasses 99.40% in the visible region (400-800 nm) and 98.63% from 400 nm to 1100 nm. The compact three-dimensional network without templates affords the double-layer coatings a robust abrasion resistance, which can withstand a scratch test of 3H pencil. HMDS treatment of the coating strengthens noticeably the surface hydrophobicity by increasing water contact angle from 30° to 126°. A particle growth mechanism was proposed and the relationship between the microstructure of silica nanoparticles and the properties of antireflective coatings is investigated. Moreover, abundant micropores coupled with a facile coating process make the coatings successfully applied onto microfiber contamination sensors.

Keywords: broadband antireflective coatings, high-sensitivity contamination sensor, microfiber-based sensor, sol-gel.