Elastic broadband antireflection coatings for flexible optics using multi-layered polymer thin films
Elastic broadband antireflection coatings for flexible optics using multi-layered polymer thin films
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使用多层聚合物薄膜的柔性光学器件的弹性宽带减反射涂层
DOI：
10.1039/d3tc00104k
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发表时间：
2023
影响因子：
6.4
通讯作者：
Tenhaeff, Wyatt E.
中科院分区：
文献类型：
--
作者：
Zhao, Yineng;Huo, Ni;Ye, Sheng;Tenhaeff, Wyatt E.
柔性光学和光电设备需要可拉伸且合规的减反射涂层 (ARC)。传统的光学涂层（通常是无机薄膜）在应变下易碎并破裂，而多孔或图案表面通常缺乏环境耐受性和/或涉及复杂的加工。通过引发化学气相沉积 (iCVD) 制备的聚合物光学薄膜是一类有前途的替代材料。通过 iCVD，可以在接近室温的温度敏感基材的表面上共形地合成多层、均匀的薄膜涂层，并精确控制成分和厚度。在本研究中，模型双层涂层设计由聚（1H,1H,6H,6H-全氟己基二丙烯酸酯）（pPFHDA）组成，其在 633 nm 处的折射率为 n633 = 1.426，沉积在聚（4-乙烯基吡啶）（p4VP，n633 = 1.587）顶部。透明、柔性热塑性聚氨酯 (TPU) 基材 (n633 ∼ 1.51) 具有可见光波长范围 (400–750 nm) 的宽带抗反射性，将前表面反射率从 ∼4% 降低到 ∼2%。通过监测施加等双轴应变时薄膜形态和拉伸断裂的演变，彻底研究了聚合物 ARC 在 TPU 基材上优于传统无机涂层（MgF2、SiO2 和 Al2O3）的机械顺应性。聚合物 ARC 至少承受 ε = 1.64% 等双轴应变而不断裂，而所有无机涂层均破裂。通过数百次循环的重复施加应变，聚合物薄膜的减反射表现出优异的稳定性和疲劳弹性。最后，对已建立的具有较大折射率对比度的 iCVD 聚合物化学的模拟表明，反射率可以进一步降低至 <1% 或更好。
Flexible optics and optoelectronic devices require stretchable and compliant antireflection coatings (ARC). Conventional optical coatings, typically inorganic thin films, are brittle and crack under strain, while porous or patterned surfaces often lack environmental endurance and/or involve complex processing. Polymeric optical thin films prepared by initiated chemical vapor deposition (iCVD) comprise a promising alternative class of materials. With iCVD, multilayered, uniform thin film coatings can be synthesized conformally on the surface of a temperature-sensitive substrate near room temperature with precise compositional and thickness control. In this study, a model two-layer coating design consisting of poly(1H,1H,6H,6H-perfluorohexyl diacrylate) (pPFHDA) with a refractive index at 633 nm of n633 = 1.426 was deposited atop poly(4-vinylpyridine) (p4VP, n633 = 1.587). Broadband antireflection over the visible wavelength range (400–750 nm) was conferred to a transparent, flexible thermoplastic polyurethane (TPU) substrate (n633 ∼ 1.51), reducing the front-surface reflectance from ∼4% to ∼2%. The superior mechanical compliance of polymer ARCs over conventional inorganic coatings (MgF2, SiO2, and Al2O3) on the TPU substrate was thoroughly investigated by monitoring the evolution of film morphology and tensile fracture with applied equibiaxial strain. The polymer ARC withstood at least ε = 1.64% equibiaxial strain without fracture, while all inorganic coatings cracked. Through a repeated application of strain over hundreds of cycles, the antireflection by the polymer film was shown to possess excellent stability and fatigue resilience. Finally, simulations of established iCVD polymer chemistries possessing larger index contrast revealed that reflectance can be further reduced to <1% or better.