Preparation of broadband antireflective coatings with ultra-low refractive index layer by sol-gel method

In this paper, a novel long-time refluxing process has been applied for ultra-low refractive index antireflective coatings preparation. Coating with refractive index of 1.12 was obtained. Double layer antireflective coatings with refractive index of 1.12 for the top layer and that of 1.30-1.40 for the bottom layer have been fabricated on soda-lime glasses. By adjusting the preparation parameters, the numerical difference between peak and valley transmittance value gradually reduced, i.e. the broadband antireflective coatings were prepared. The light transmittance of double layer antireflective coatings achieved to 99.04%, while the average transmittance attained to 95.49% in 300-1200 nm wavelength. (C) 2018 Elsevier Ltd. All rights reserved.