| With the excessive consumption of fossil energy and other non-renewable energy(coal,oil),the global substantial energy presents a state of scarcity in resent years.Renewable clean energy based on solar energy has received unprecedented attention when the energy crisis comes nearly.Highly efficient access to solar energy is the primary goal of many scientific researchers to change energy mix.In addition,with the rapid development of information technology and the popularity of a variety of personalized information equipment,the use frequency of electronic screens has greatly increased.The glare caused by liquid crystal display(LCD)screens is an important reason for the current visual impairment.More importantly,the strong reflection of glass curtain wall will cause the massive spread of light pollution.Therefore,it is of great significance to explore the application of antireflection(AR)technology in these fields for improving national life and energy mix.In order to solve the problem of excessive reflection of optical surfaces,the technology of preparing AR surfaces has been vigorously developed in the past 100 years.According to the researches in recent decades,the AR surfaces can be divided into 3 kinds based on their function:high transmittance AR surface,light-trapping AR surface and diffuse reflection AR surface.The principle of AR is to reduce the reflected light generated at the interface between aircoating and coating-substrate.The early fabricated AR surfaces are mostly relied on the principle of half wave loss(quarter interference extinction).Although this technology is relatively mature,its shortcomings such as low efficiency,narrow action band and poor mechanical stability limit the popularity of AR surfaces and their applications in high-tech fields.Luckily,with the development of AR coating technology,AR structures have gradually attracted the attention of most researchers because of their excellent performance.AR structure is mostly prepared on the substrate surface by a variety of means.The gradient changing with the structure from top to bottom,an air-material composite layer with slow change of refractive index can be formed on the substrate surface,achieving the purpose of antireflection.Compared with the traditional AR film,the AR structures have broader functional band,wider functional angle and better transmission/trapping ability.However,how to design and prepare AR structures with specific function is a major difficulty that limits the development of current AR technology.In addition,the existing AR structures and their main functions have not developed into a relatively mature theory.The design and optimization of their structures and parameters are very complicated.The systematic research and development is also relatively inestimable.Fortunately,it is worth noting that creatures living in nature can provide complete perfect solutions for many tough challenges at this stage.After hundreds of millions of years of natural selection and evolution,the structures and specific function of organisms have experienced thousands of tests in nature,including tissues and organs with excellent antireflection ability.Exploring the principle of antireflection of specific biological tissues and their structures is a shortcut to break through the limitations of antireflection technology at moment.Dragonflies are the most successful killers in nature.Their predation success rate is as high as 95%.Most of them live in tropical or subtropical near water areas,where are often full of danger due to the complex environment.Their complex eyes give them extraordinary vision,finding natural enemies and prey in time and making avoidance or predation behavior,so that they can survive for hundreds of millions of years.Compared with other insects,their larger compound eyes show strong AR ability.However,existing research mainly focuses on the AR performance of the 2D surface structure,while ignoring the internal 3D structures that possess a more intimate and elaborate interaction with light.Accordingly,the internal exquisite structures and the underlying superior AR mechanism have not been revealed so far.Based on the AR characteristics of the internal tissue of dragonfly compound eye,this paper deeply explores the interaction process between the microstructure of its internal tissue and light to reveal the omnidirectional AR mechanism of the wrinkled hierarchically architected structure.The bioinspired wrinkled hierarchically architected structure has been successfully prepared on the glass substrate are tested and characterized its omni-directional antireflection performance.Then,according to different application backgrounds and actual demands,the AR coating is combined with various functions to explore the practical application of AR technology in many fields.The research content of this paper will be divided into the following five parts:(1)Wrinkled hierarchically architected structure and its antireflection mechanism.The lamellar biological tissue inside the dragonfly compound eye has excellent antireflection performance.Their complicated and precise structure is the key to give full play to the highefficiency antireflection ability.In this paper,the wrinkled hierarchically architected structure on the inner lamellar tissue of the compound eye of the scarlet Dragonfly(hydrobasileus croceus)is observed and found by SEM and ultra-depth of field microscope.Its optical properties are tested by optical fiber spectrometer.The three-dimensional model is established based on similarity theory.And the optical properties and advantages of the wrinkled structure are simulated and analyzed by FDTD solutions.The omnidirectional antireflection performance of wrinkled hierarchically architected structure is revealed.(2)Preparation of omnidirectional AR coating with wrinkled structure on glass substrate.Based on the glass substrate,the bioinspired antireflection coating with wrinkled hierarchically architected structure was prepared by the method including spin coating and thermal decomposition process.The effects of different preparation conditions on the optical properties of AR coatings were discussed,and the best preparation conditions were selected based on the principle of light transmittance priority.The large-area preparation was completed under the best preparation conditions,and the angle dependence analysis was carried out by spectrometer.The adhesion between the coating and glass substrate was tested by scratch test,and the durability and optical properties of the coating were tested by sand falling test.(3)Referring to the principle of preparing anti-glare(AG)materials at the present stage,the AG film is successfully prepared by co-dissolution method using the above prepared wrinkled structure as the template,with PDMS as the substrate and PMMA as the internal scattering phase.The light transmittance is tested by spectrometer.The haze of films with different PMMA addition is tested by Haze-meter.The friction coefficient of the surface is tested by nano-scratch instrument.The modified elastic modulus is finally tested by tensile testing machine.The preparation scheme of AG film based on wrinkled structure is summarized,and AG films with different haze can be prepared according to different demand.(4)Based on the problem of reducing the excessive reflection on the metal surface during present stage,the AR coating developed above is applied to the aluminum base surface to achieve its excellent AR effect.In addition,aiming at the problem of metal heat dissipation,the infrared passive heat dissipation method is given to the conventional aluminum base surface by preparing antireflection coating.The reflected light intensity after coated is tested by spectrometer.The morphology change of the surface is observed by ultra-depth of field microscope.The heat dissipation capacity is tested by infrared thermal imager.The heat dissipation capacity under different heating temperatures is tested.The cooling capacity is finally tested.(5)In view of the low photoelectric conversion efficiency of polycrystalline silicon solar panels at this stage,the AR coating is prepared on polycrystalline silicon solar cells to complete the further processing after flocking,reducing its reflectivity in short wave band.The solar cell with AR coating is photographed by digital camera.The open circuit voltage under different illuminance is measured by multifunctional digital multimeter.Then,the voltage output test of different solar panels is carried out.The output end is connected to the fan.The speed is measured by infrared tachometer,analyzing the improvement of photoelectric conversion efficiency with antireflection coating.In this paper,the idea of bionics is used to solve the problems caused by optical surface reflection in practical production and life.The innovation lies in: finding the super AR performance of the wrinkled hierarchically architected structure on the lamellar biological tissue inside the dragonfly compound eye,revealing its omni-directional antireflection mechanism,combining the modeling through the similarity theory,and in consideration of the theoretical analysis through the gradual refractive index and equivalent refractive index theory,the verification is completed by simulation test;the integrated preparation technology of bionic wrinkled hierarchically architected structure is developed.Through the integration of spin coating method and thermal decomposition method,the purpose of large-area preparation of precision wrinkled hierarchically architected structure on the substrate is realized;according to different application requirements,the AR coating is explored and extended to a variety of substrates.At the same time,it realizes the ability of anti-glare,passive heat dissipation and improving photoelectric conversion.Promote the feasibility application of bionic AR technology in practical production and life. |
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