Low-temperature preparation of nanostructured porous sol-gel anti-reflective coating for near-infrared wavelengths

Abstract

Anti-reflective coatings are crucial in minimizing reflection between different optical media at the interfaces. This study aims to develop an anti-reflective layer for the near-infrared region using a sol-gel coating method combined with a low-temperature plasma-jet-assisted surfactant extraction. For the deposition of the sol-gel layer on glass and polycarbonate substrates, dip-coating and spray-coating techniques were used. Surfactant removal was carried out using a plasma-jet and solvent exchange. Some of the samples were also annealed at 450 °C. The samples were characterized through light transmission measurements, haze percentage determination, 3D laser scanning microscopy, scanning electron microscopy, profilometry, Fourier transform Infrared spectroscopy, ellipsometry and atomic force microscopy. The results showed that the anti-reflective coating layer treated with a plasma-jet and solvent exchange at room temperature demonstrated broadband anti-reflective properties with high transmission in near-infrared regions (up to 7.6% relative improvements in transmission for two sides). Annealing, performed only on the glass substrate, also showed the maximum relative improvement in transmission up to 8% for two sides. Moreover, in the case of polymer-based substrates, a low-temperature process is essential, which is implemented successfully by a plasma-jet method. These findings highlight the effectiveness of the proposed method for fabricating anti-reflective layers on both glass and polycarbonate substrates, offering potential applications in various industries, e.g. where either low-temperature fabrication or cost-cutting, quick and “simple” production methods play a major role for the feasibility of products as in mass markets.