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

• Published in: Nanomaterials (Basel, Switzerland) Vol. 11; no. 8; p. 1954
• Main Authors: Liang, Chih-Hao, Chen, Ying-Jung
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 29.07.2021; MDPI
• Subjects: Absorption; Anatase; Cathodic coating (process); Coatings; Crystallization; Cytokines; Evaporation; fibroblasts; Film thickness; Free electrons; Glass substrates; heat insulation; human skin; Humidity; Inflammation; Insulation; ITO; Light; Light transmittance; Magnetron sputtering; Metal oxides; Multilayers; Near infrared radiation; Optical design; Photocatalysis; Radiation; Reactive oxygen species; Resonance absorption; Shielding; Silicon dioxide; Skin; Substrates; Thin films; TiO2/SiO2 multilayers; Titanium dioxide; UV absorption; TiO2/SiO2 multilayers; UV absorption; fibroblasts; ITO; heat insulation; human skin
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano11081954

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.