Preparation of High-Performance Metal-Free UV/Near Infrared-Shielding Films for Human Skin Protection.

Chih-Hao Liang,Ying-Jung Chen

doi:10.3390/nano11081954

Abstract

A series of metal-free UV/near infrared (NIR)-shielding coatings are successfully fabricated by shielded cathodic arc plasma evaporation (CAPE) and substrate-biased RF magnetron sputtering processes. The UV/NIR-shielding coatings comprising quarter-wave stacks of TiO2/SiO2 multilayers and high-conductivity sputter-deposited ITO films with a thickness in the range of 200–600 nm could block IRA and IRB radiations, respectively. The total thicknesses of UV/near infrared-shielding films are in the range from 375 nm to 1513.8 nm. The anatase-phase TiO2 films with absorption edge located at ~375 nm were deposited by shielded CAPE at ~100 °C. Further, the well-crystallized ITO films were found to have high free-electron concentrations (1.12 × 1021 cm−3), resulting in strong absorption of IRB due to the plasmon resonance absorption. The optimal optical design and ITO film thickness were investigated, and the TiO2(SiO2/TiO2)3 multilayer combined with an ITO film thickness of 400 nm was found to provide a high NIR-shielding rate of 94.8%, UVB to UVA-shielding rate of 92.7%, and average visible light transmittance of 68.1%. Further, human skin cells protected by a UV/NIR-shielding coating showed significantly decreased reactive oxygen species generation and inflammatory cytokine expression as compared to those of unprotected cells. The results demonstrate that the development of multifunction coatings have potential for transparent heat insulation windows and human skin protection against UV/IR radiations.

Highlights

Solar radiation near the Earth’s surface consists of a wide range of wavelengths, divided into three main ranges: UV, visible, and infrared (IR) radiations
We employed a novel method to fabricate a metal-free UV/NIR-shielding coating with high IR- and UV-shielding performance and high transmittance in visible light for energy-saving applications and human skin protection
These double-sided coatings consist of quarter-wave stacks of SiO2 /TiO2 multilayers and indium tin oxide (ITO) films on different side of glass, which were responsible for blocking the IRA and IRB radiations, respectively

Summary

Introduction

Solar radiation near the Earth’s surface consists of a wide range of wavelengths, divided into three main ranges: UV, visible, and infrared (IR) radiations. While the IR light comprises ~54% of the total amount of the solar energy, the UV light (including the three types: UVA, UVB, and UVC) accounts for only 7% [1]. Sunscreen materials are widely used in UVA (wavelength: 320–400 nm) and UVB (wavelength: 280–320 nm) protection for reducing the risk of skin cancers such as basal-cell carcinoma [3] and squamous-cell carcinoma [4]. Recent studies have indicated that IR light, which is subdivided into IRA (wavelength: 760–1400 nm), IRB (wavelength: 1400–3000 nm), and IRC (3000 nm to 1 mm) ranges, can cause skin damage and aging under prolonged sunlight exposure [6]. IRA radiation comprises a major portion of the IR wavelengths of the sunlight, and has a 65% skin-penetration rate, Nanomaterials 2021, 11, 1954.

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