Hyperreflective photonic crystals created by shearing colloidal dispersions at ultrahigh volume fraction  

作　　者：Minji Kim Jong Bin Kim Shin-Hyun Kim 

机构地区：[1]Department of Chemical and Biomolecular Engineering,Korea Advanced Institute of Science and Technology(KAIST),Daejeon 34141,Republic of Korea

出　　处：《Microsystems & Nanoengineering》2024年第1期161-173,共13页微系统与纳米工程（英文）

基　　金：supported by the National Research Foundation of Korea(NRF-2022M3C1A3081312).

摘　　要：Colloidal crystallization serves as one of the most economic and scalable production methods for photonic crystals.However,insufficient optical performance,nonuniformity and low reproducibility remain challenges for advanced high-value applications.In this study,we optimally formulate a photocurable dispersion of silica particles and apply shear flow to unify the orientation of the colloidal crystals,ensuring high optical performance and uniformity.The silica particles experience strong repulsion at ultrahigh volume fractions of 50%but demonstrate low mobility,leading to polycrystalline structures.Applying shear flow to the dispersions allows the silica particles to rearrange into larger crystalline domains with a unidirectional orientation along the flow.This shear-induced structural change produces absolute reflectivity at the stopband as high as 90%and a high transparency of 90%at off-resonant wavelengths with minimal diffusive scattering.Furthermore,the strong interparticle repulsion ensures a uniform volume fraction of particles throughout the dispersion,reducing deviations in the optical properties.We intricately micropattern the photocurable dispersions using photolithography.Additionally,the photonic films and patterns can be stacked to form multiple layers,displaying mixed structural colors and multiple reflectance peaks without sacrificing reflectivity.These superior photonic materials hold promise for various optical applications,including optical components and anticounterfeiting patches.

关 键 词：properties. DISPERSION REFLECTIVITY 

分 类 号：O63[理学—高分子化学]