Broadband single- and double-layer composite nanoporous coatings based on SiO$_2$@Cu)(ZnO) to increase glass transparency

Background and Objectives: Using sol-geltechnology, silicate mesoporous single layer coatings based on SiO$_2$@CuO(ZnO) compositions were obtained to increase glass transparency. The phase composition and properties of powders obtained from dried sols were studied. The optical properties of the obtained silicon oxide sols were explored by the turbidimetric method. To identify the characteristics of gelation and coagulation, a spectrophotometric study of the silicon oxide sol was carried out. The resulting sols were applied to glass by adsorption from solution (dip-coating) at room temperature (23 $\pm$ 10$^{\circ}$C). The rate of extraction from the solution varied from 105 to 160 mm/min. Glasses with coatings applied to both sides were dried at room temperature until a film formed and subjected to heat treatment in a muffle furnace at a temperature of 500$^{\circ}$C. At the moment of annealing, the decomposition of copper and zinc salts and the formation of a composite composition of SiO$_2$@CuO and SiO$_2$@ZnO films occurred. Spectral measurements of the transmittance and reflection of glasses with single layer mesoporous coatings were carried out in the range of 400–800 nm. Materials and Methods: To obtain sols with copper and zinc, metal salts Zn(CH$_3$CO$_2$)$_2$ $\cdot$ 2H$_2$O and (CH$_3$COO)$_2$Cu $\cdot$ H$_2$O (6$\%$ or 10$\%$ by weight SiO$_2$) were added to the SiO$_2$ sol. Using a magnetic stirrer, the resulting mixtures were stirred at room temperature for 15 $\pm$ 0.5 min. To study the optical properties of the sols, a base SiO$_2$ sol and SiO$_2$ sols with the addition of zinc acetate and copper acetate (6$\%$ and 10$\%$ by weight of silicon dioxide) were prepared. After heat treatment, the thickness of the applied coatings was determined by contact method using a Dektac-150 profilometer. It was determined that the thickness of the coatings on glass varied from(95 $\pm$ 20) to (137 $\pm$ 7) nm at drawing speeds of 105 and 160 mm/min, respectively. Results: The developed methods for producing mesoporous silicate coatings on glass have ensured the creation of homogeneous coatings with good adhesion, uniform thickness and roughness. The results of measuring the transparency spectra of glass with a single layer coating of sols with different compositions and drawing rates have been presented. It has been shown that double-sided single-layer mesoporous SiO$_2$@CuO(ZnO) composite coatings with different compositions demonstrate an increase in glass transparency by 2-3$\%$ in a wide optical range of 400–1000 nm. Conclusion: The proposed composition of compositions in single layer film structures makes it possible to solve the problem of broadband antireflection of glasses in a wide range of optical wavelengths (400–1000 nm).