journal article·2023-06Open access

Fabrication of a porous SiO2 thin film with an ultralow refractive index for anti-reflective coatings

Ryoko Suzuki

Abstract

Abstract Anti-reflective (AR) coatings are used in various optical products, such as lenses, filters, and transparent conductive films. High-performance multilayer AR coatings can be achieved by reducing the refractive index of the top layer. Preventing light scattering by forming finely structured film is also important for a high-performance antireflection film. In this study, porous SiO2 thin films with ultralow refractive indices were prepared using a simple sol–gel method. A high-quality porous SiO2 thin film with an ultralow refractive index of 1.17 bearing a fine porous structure was fabricated by carefully selecting the solvent and base species. Observation and simulation of the film structure revealed the factors responsible for the low scattering of light and the ultralow refractive index exhibited by the film. Hydrophobic treatment of the film was conducted to reduce the fluctuation of optical performance caused by changes in the refractive index owing to the water adsorbed. Therefore, porous SiO2 thin films can be used in the lenses and filters of various optical instruments. Graphical abstract
Source: crossref · Quality: baseline

Research context

OpenAlex topics: Optical Coatings and Gratings · Surface Modification and Superhydrophobicity · Photonic Crystals and Applications

SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.

References (32)

Show source-provided references
1. Shanbhogue HG, Nagendra CL, Annapurna MN, Kumar SA, Thutupalli GKM (1997) Multilayer antireflection coatings for the visible and near-infrared regions. Appl Opt 36:6339–635110.1364/AO.36.006339 ↗
2. Li X, Gao J, Xue L, Han Y (2010) Porous polymer films with gradient-refractive-index structure for broadband and omnidirectional antireflection coatings. Adv Funct Mater 20:259–26510.1002/adfm.200901052 ↗
3. Chen D (2001) Anti-reflection (AR) coatings made by sol–gel processes: A review. Solar Sol Energy Mater Sol Cells 68:313–33610.1016/S0927-0248(00)00365-2 ↗
4. Sun X, Tu J, Li L, Zhang W, Hu K (2020) Preparation of wide-angle and abrasion-resistant multi-layer antireflective coatings by MgF2 and SiO2 mixed sol. Colloids Surf A 602:12510610.1016/j.colsurfa.2020.125106 ↗
5. Zhang X, Lan P, Lu Y, Li J, Xu H, Zhang J, Lee YP, Rhee JY, Choy KL, Song W (2014) Multifunctional antireflection coatings based on novel hollow silica–silica nanocomposites. ACS Appl Mater Interfaces 6:1415–142310.1021/am405258d ↗
6. Thomas IM (1988) Porous fluoride antireflective coatings. Appl Opt 27:3356–335810.1364/AO.27.003356 ↗
7. Fujihara S, Kadota Y, Kimura T (2002) Role of organic additives in the sol-gel synthesis of porous CaF2 anti-reflective coatings. J Sol Gel Sci Tech 24:147–15410.1023/A:1015252010509 ↗
8. Yamaguchi N, Tadanaga K, Matsuda A, Minami T, Tatsumisago M (2007) Antireflective properties of flowerlike alumina thin films on soda–lime silica glass substrates prepared by the sol–gel method with hot water treatment. Thin Solid Films 515:3914–391710.1016/j.tsf.2006.11.009 ↗
9. Thomas IM (1986) High laser damage threshold porous silica antireflective coating. Appl Opt 25:1481–148310.1364/AO.25.001481 ↗
10. Moghal J, Kobler J, Sauer J, Best J, Gardener M, Watt AAR, Wakefield G (2012) High-performance, single-layer antireflective optical coatings comprising mesoporous silica nanoparticles. ACS Appl Mater Interfaces 4:854–85910.1021/am201494m ↗
11. Vincent A, Babu S, Brinley E, Karakoti A, Deshpande S, Seal S (2007) Role of catalyst on refractive index tunability of porous silica antireflective coatings by sol−gel technique. J Phys Chem C 111:8291–829810.1021/jp0700736 ↗
12. Peeters MPJ, Bohmer MR (2003) Optical application of (pigmented) sol-gel coatings. J Sol Gel Sci Technol 26:57–6210.1023/A:1020781116986 ↗
13. Murray C, Flannery C, Streiter I, Schulz SE, Baklanov MR, Mogilnikov KP, Himcinschi C, Friedrich M, Zahn DRT, Gessner T (2002) Comparison of techniques to characterise the density, porosity and elastic modulus of porous low-k SiO2 xerogel films. Microelectron Eng 60:133–14110.1016/S0167-9317(01)00589-5 ↗
14. Wang Z, Gu Z (2009) Optical humidity-sensitive mechanism based on refractive index variation. Chin Opt Lett 7:756–75910.3788/COL20090709.0756 ↗
15. Dou W, Wang P, Zhang D, Yu J (2016) An efficient way to prepare hydrophobic antireflective SiO2 film by sol-gel method. Mater Lett 167:69–7210.1016/j.matlet.2015.12.146 ↗
16. Zhang S, Xiao P, Wang P, Luo J, Jiang B (2020) Spherical-chain silica with super-hydrophobic surface and ultra-low refractive index for multi-functional broadband antireflective coatings. Sol Energy 207:1222–123010.1016/j.solener.2020.05.060 ↗
17. Huang X, Yuan Y, Liu S, Zhang L, Hong R (2018) Preparation of hydrophobic broadband antireflective SiO2 coating on flexible poly (methyl methacrylate) substrates. Colloid Surf A Physicochem Eng Asp 538:519–52510.1016/j.colsurfa.2017.11.027 ↗
18. Hsu H-T, Ting C-Y, Mou C-Y, Wan B-Z (2003) Nanoporous SiO2 films prepared by surfactant templating method - a novel antireflective coating technology. Stud Surf Sci Catal 146:539–54210.1016/S0167-2991(03)80440-8 ↗
19. Ren H, Zhu J, Bi Y, Xu Y, Zhang L (2018) Assembly of methylated hollow silica nanospheres toward humidity-resistant antireflective porous films with ultralow refractive indices. J Porous Mater 25:55–6210.1007/s10934-017-0420-3 ↗
20. Rouse JH, Ferguson GS (2003) Preparation of thin silica films with controlled thickness and tunable refractive index. J Am Chem Soc 125:15529–1553610.1021/ja036241z ↗
21. Rand MJ (1970) Spectrophotometric thickness measurement for very thin SiO2 films on Si. J Appl Phys 41:78710.1063/1.1658750 ↗
22. Makita K, Akamatsu Y, Takamatsu A (1999) Sol-gel preparation of silica films with controlled surface morphology and their application to a low reflective glass. J Sol Gel Sci Technol 14:175–18610.1023/A:1008738117124 ↗
23. Hancock RD, Nakani BS, Marsicano F (1983) Relationship between Lewis acid-base behavior in the gas phase and in aqueous solution. 1. Role of inductive, polarizability, and steric effects in amine ligands. Inorg Chem 22:2531–253510.1021/ic00160a014 ↗
24. Coetzee JF, Padmanabhan GR (1965) Properties of bases in acetonitrile as solvent. IV. Proton acceptor power and homoconjugation of mono- and diamines. J Am Chem Soc 87:5005–501010.1021/ja00950a006 ↗
25. Cantu MD, Hillebranda S, Carrilho E (2005) Determination of the dissociation constants (pKa) of secondary and tertiary amines in organic media by capillary electrophoresis and their role in the electrophoretic mobility order inversion. J Chromatogr A 1068:99–10510.1016/j.chroma.2004.12.009 ↗
26. Misheva M, Djourelov N, Margaca FMA, Salvado IMM (2001) Positronium study of porous structure of sol–gel prepared SiO2: influence of pH. J Non Cryst Solids 279:196–20310.1016/S0022-3093(00)00405-1 ↗
27. Falcaro P, Grosso D, Amenitsch H, Innocenzi P (2004) Silica orthorhombic mesostructured films with low refractive index and high thermal stability. J Phys Chem B 108:10942–1094810.1021/jp037740p ↗
28. Hasegawa K, Nasu A, Fuita M (2016) Behavior analysis of coating layer particles in cosmetic materials during drying by observation and computational simulation. Josai Math Monogr 9:75–88
29. Fujita M, Yamaguchi Y (2006) Development of three-dimensional structure formation simulator of colloidal nanoparticles during drying. J Chem Eng Jpn 39:83–8910.1252/jcej.39.83 ↗
30. Jain PK, Lee KS, El-Sayed IH, El-Sayed MA (2006) Calculated absorption and scattering properties of gold nanoparticles of different size, shape, and composition: applications in biological imaging and biomedicine. J Phys Chem B 110:7238–724810.1021/jp057170o ↗
31. Nalamasu O, Cheng M, Timko AG, Pol V, Reichmanis E, Thompson LF (1991) An overview of resist processing for deep-UV lithography. J Photopolym Sci Technol 4:299–31810.2494/photopolymer.4.299 ↗
32. Hirotsu T, Tagaki C (2004) Plasma copolymer membranes of acrylic acid and the adsorption of lysozyme on the surface. Thin Solid Films 457:20–2510.1016/j.tsf.2003.12.005 ↗