Fabrication of flexible photonic crystal structures with applications in full color grating and multiple anti-counterfeiting labels

• Main Authors: Chang-I Peng, 彭長毅
• Other Authors: 王國禎
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/26531806673553443455

碩士 === 國立中興大學 === 機械工程學系所 === 105 === In this study, a method that enables the mass production of flexible photonic crystal structures possessing nano full-color grating, allowing diverse structural colorations, is presented. Optical properties of the flexible photonic crystal structures and their feasible applications are investigated. The uniformly distributed nano-hemisphere array of the barrier layer of an anodic aluminum oxide (AAO) membrane is used as the template for nickel electroforming to obtain a nickel nano-mold. The nickel nano-mold is further used for repeatedly imprinting of flexible Polycarbonate (PC) films with a designed photonic crystal structure. The fabricated flexible PC films can be used as a white light grating. By means of different angles of incidence or different viewing angles, the structural color change can be clearly observed, even under indoor visible light. By means of different angles of incidence or different directions of observation, the structural color change can be clearly observed. In addition, the fabricated flexible PC films can produce a variety of colors by changing the angle of the incident light through geometric deformation. The phenomenon results from the unique diffraction characteristics of the flexible PC films. Through the Bragg diffraction formula, it is confirmed that the photonic crystal structure on the flexible PC films can transfer part of the light energy to the second order diffraction spectrum. Furthermore, the flexible PC films can reveal different structural colorations under bending or coating of transparent substances with different surface tensions to exploit its optical properties for various applications. In addition, an anti-counterfeiting feature is also successfully achieved when fluorophores are patterned on the back of the polymer film and excited with UV-light irradiation.