Research On Large-area Color Filter Based On Micro/nano Structure

Color filter is a crucial component of display/imaging devices,color printing,decoration,consumer products,etc,which dominantly determines the color quality,embracing color vibrancy,saturation,gamut,brightness,and resolution.The conventional commercial color filter relies on the absorption characteristic of pigment/dye for a specific wavelength to generate a certain chemical color.The essence of chemical color totally depends on the intrinsic property of pigment/dye,so it is required to use different kinds of pigments/dyes to generate different colors.Additionally,the chemical color holds the disadvantages of being environmentally unfriendly and prone to fading,owing to the fact that the pigments/dyes are toxic and are quite sensitive to UV light and high temperatures.Given this,a nature-inspired method of physical color generation,namely,structural color that originates from physical phenomena such as scattering,interference,or diffraction excited by the interaction between light and nanostructures,has gained abundant attention.This new color generation concept enables the generation of vivid colors by simply tuning the geometric parameters or arrangement of nanostructures,leading to a more flexible color toning method,and it has prospects in traditional display,dynamic display,optical encryption and colorimetric sensor applications.Scientists have realized a variety of color filters based on different micro-nano structures such as planar thin-film and nano-array.Among them,the color filter based on the planar thin-film structure has the advantages of simple preparation method,large-area,and angle-insensitive.However,the planar thin-film structure still face the problem of incompatibility between ultra-thin properties and high color saturation.The color filter based on the nano-array structure has strong advantages in terms of color saturation and ultra-thin characteristics,and due to the large surface area of the nano-array structure,this color filter can also be used in the field of sensing.However,the fabrication of nano-array structures usually relies on expensive and complex photolithography processes,making it difficult to realize color filters in large-areas.（1）In view of the problems existing in the color filter based on the planar film structure,we first theoretically verified that the color saturation of the ultra-thin planar film structure is mainly affected by the imaginary part of the complex refractive index of the film layer.Further,based on the effective medium theory,a high-performance color filter based on an ultrathin magnesium hydride（Mg H₂）-hydrogenated amorphous silicon（a-Si:H）hybrid thin-film layer is proposed.By changing the thickness of the Mg H₂ layer,the imaginary part of the complex refractive index of the hybrid thin-film layer can be adjusted arbitrarily to obtain a target value,thereby improving color saturation.It has been verified that the designed color filter can effectively improve the color saturation and widen the color gamut under the premise of ensuring ultra-thin characteristics,and also has good angle-insensitive,and in view of the active chemical properties of the material Mg H₂ we used,the color filter also has dynamic color tuning property.（2）Aiming at the problem that the nano-array structure cannot be realized in large-area,this thesis proposed to use a low-cost self-assembled ultrathin nanopore array film,that is,anodic aluminum oxide（Anodic Aluminum Oxide,AAO）as a pattern mask to prepare nano-arrays.Based on the ultrathin AAO template and using the thermal evaporation technology,we successfully manufactured a large-area silver（Ag）nanoparticle array structure for the construction of color filters,and the prepared color filters were used for colorimetric sensing.Through experiments,it is verified that the color filter can display different colors in liquids with different refractive indices,so as to realize the visual monitoring of different liquids.