Nanostructured antireflective bilayers: Optical design and preparation

• Published in: Materials chemistry and physics 2014-05, Vol.145 (1-2), p.176-185
• Main Authors: Detrich, Ádám, Nagy, Norbert, Nyári, Mária, Albert, Emőke, Zámbó, Dániel, Hórvölgyi, Zoltán
• Format: Article
• Language: English
• Subjects: Coatings; Multilayers; Nanostructures; Optical properties; Sol–gel growth; Visible and ultraviolet spectrometers
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2014.01.056

We show different methods for tailoring and fabrication of various cost-effective antireflective nanocoatings on transparent and non-transparent substrates. The main purpose was to prepare coatings with decreased reflectance in the full visible wavelength range using simple wet layer deposition techniques. Structure of coatings was designed by optical simulations applying simplified calculations. The refractive index of substrates was also considered for the calculations. The advantageous optical properties were achieved by bilayered structures combining compact and porous sol–gel derived oxide layers and nanoparticulate films. The bilayered structures enhance the flexibility of design by not only the selection of the layer thicknesses but also by different ways of adjusting the effective refractive index of the layers. Furthermore, chemical stability of the coatings was also investigated. The optical and structural properties of prepared films and bilayered coatings were studied by UV–vis spectroscopy and scanning electron microscopy, respectively. The transmittance of coated glass substrates was above 97.5%, while the reflectance of coated silicon substrates was below 4% between 450 nm and 900 nm. •Designed antireflective bilayered coatings on glass and silicon.•Simple, colloid chemical approaches to preparation.•Favorable optical properties by combining compact and porous oxide layers.•Different ways for adjusting the effective refractive index.•Strong chemical resistance against acidic effects.