Highly transparent polyimide/nanocrystalline-titania hybrid optical materials for antireflective applications |
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Authors: | Yang-Yen Yu Wen-Chen Chien Tsung-Heng Wu Hui-Huan Yu |
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Affiliation: | aDepartment of Materials Engineering, Mingchi University of Technology, 84 Gunjuan Road, Taishan, New Taipei City 243, Taiwan;bDepartment of Chemical Engineering, Mingchi University of Technology, 84 Gunjuan Road, Taishan, New Taipei City 24301, Taiwan;cCenter for Thin Film Technologies and Applications, Mingchi University of Technology, 84 Gunjuan Road, Taishan, New Taipei City 24301, Taiwan |
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Abstract: | This study prepared polyimide/titania hybrid thin films of, poly(3,3′,4,4′-Benzophenone tetra carboxylic dianhydride)–(4,4-Diaminodiphenyl Ether)/nanocrystalline titania (BTDA-ODA/TiO2), with a high refractive index. FTIR analysis confirmed the formation of a polyimide and titania matrix. TGA and DSC analysis gauged the decomposition temperature in the range of 455–532 °C, indicating that the addition of titania could increase the glass transition temperature of hybrid films. XRD results indicate the formation of nanocrystalline titania domains of approximately 8–11 nm in the hybrid films. AFM, SEM, TEM, and XRD results show the formation of well-dispersed nanocrystalline titania. The refractive index was measured by ellipsometry, demonstrating an increase in the refractive index of the prepared hybrid thin films from 1.657 to 1.958, when the titania content was increased from 0 to 90 wt.%. UV–vis analysis gauged the cutoff wavelength in the range of 288–357 nm. The prepared polyimide/titania hybrid thin films were used to develop a three layer antireflective (AR) coating on a glass substrate. The average reflectance of the AR was 0.5% for the PT20/PT90/F-siloxane layer and 0.6% for the PT20/PT90/porous silica. Transparency at 550 nm exceeded 90% for both AR coatings. |
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Keywords: | Polyimide Titania nanocrystalline Roughness Refractive index Cutoff wavelength Antireflective coating |
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