Preparation and Property of Superhydrophobic Antireflective Film with Gradient Refractive Index

doi:10.15541/jim20170575

Abstract

Abstract:

Gradient refractive index antireflection film achieves antireflective performance in wider spectrum band at larger incident of angle. In this study, solid silica nanometer particles (SiO₂) sol and hollow silica nanometer particles (H-SiO₂) sol were synthesized by Sol-Gel method, while hollow rod-shaped magnesium fluoride nanometer particles (MgF₂) sol was prepared by solvothermal method. Then, the SiO₂/H-SiO₂/MgF₂ gradient refractive index antireflection film was successfully coated on double sides of borosilicate glass by dip-coating method. The experimental results show that in the wavelength range of 380~1600 nm, when light is incident vertically, the transmittance of the coated glass reaches 99.88%; when the light is at the incident angle of 0°~45°, with the average transmittance higher than 97.85%. And the light is even at the incident angle of 75°, its maximum transmittance is still as high as 95.51%. After modified by hexadecyl trimethoxysilane (HDTMOS) the contact angle of the coated glass is up to 150.6°, showing good hydrophobic self-cleaning performance.

Key words: gradient refractive index, omnidirectional, broadband, hydrophobic, antireflective film

CLC Number:

TB34

JIA Gui-Yu, LI Yi-Wen, WANG Hong-Ning, CHEN Ruo-Yu. Preparation and Property of Superhydrophobic Antireflective Film with Gradient Refractive Index[J]. Journal of Inorganic Materials, 2018, 33(9): 1011-1016.

Figures/Tables 7

Fig. 1 TEM images of (a) solid SiO2 particles, (b) H-SiO2 particles and (c) hollow rod-shaped magnesium fluoride

Fig. 2 FESEM (a) surface image, and (b) cross-sectional image of the SiO2/H-SiO2/MgF2 film

Table 1 Ellipsometer test results of SiO2, H-SiO2, MgF2 films

Layer position	Material	Thickness/nm	n¹ ₍_λ_{= 550 nm)}
Layer 1	SiO₂	110	1.36
Layer 2	H-SiO₂	125	1.25
Layer 3	MgF₂	135	1.14

Fig. 3 Transmittances of (a) the blank substrate and the coated substrates with SiO2 monolayer, SiO2/H-SiO2 bilayer, and SiO2/H-SiO2/MgF2 three-layer graded refractive index film in the wavelength of 380-1600 nm, (b) the coated substrate with SiO2/H-SiO2/MgF2 film at different angles of incidence, and (c) three-dimensional transmittances of the coated substrate with SiO2/H-SiO2/MgF2 film

Fig. 4 (a) Optical path of the light enters in the substrate through three-layer coating, (b) Fresnel reflection coefficients at the coating interfaces at different angles of incidence

Fig. 5 Theoretical and experimental and polarization transmittance curves of the SiO2/H-SiO2/MgF2 three-layer graded refractive index film coated substrate at the incident angles of (a) 0°, (b) 30°, (c) 60°, (d) 75°

Fig. 6 (a) Water contact angle and AFM pattern of the SiO2/H-SiO2/MgF2 gradient index film, and (b) water contact angle of the SiO2/H-SiO2/MgF2 film was modificated by HDTMOS

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