| Infrared absorbers with tunable spectra have important application value in the field of radiant heat management,including thermal photovoltaic systems,radiant cooling devices,infrared imaging,and infrared stealth coatings.For infrared absorbers,the absorption spectra should be tunable in a wide band to meet different application requirements.However,the common infrared absorbers that have to satisfy the two characteristics of broadband absorption and spectral adjustment,usually have a fine asymmetric structure or a complex multi-size unit structure.This will make the preparation process of the absorber very complicated and seriously hinder its mass production and application at high frequencies.In order to overcome the above-mentioned difficulties,this paper designs a nanocomposite metamaterial infrared absorber with a wide tunable range and a simple structure.The metamaterial absorber uses an Al-doped zinc oxide(AZO)particle layer dispersed in a medium,which is separated from the bottom Al reflector by a dielectric layer.Compared with previous work,this absorber has a wider absorption potential,and can flexibly adjust the peak position and width of the absorption spectrum.On this basis,this paper first puts forward the "imaginary part selection method",a theoretical principle that guides the structure design of nanocomposite metamaterials;secondly,this paper reveals the absorption mechanism behind different characteristic spectra;finally,this paper experimentally uses simple rotation The coating method prepared broadband absorbers with high emission at 3-15 μm and selective absorbers with high emission at 5-8 μm,and realized the functions of daytime radiation cooling and infrared stealth thermal control respectively.The research in this paper provides a design strategy for the design of metamaterials with tunable electromagnetic response,and lays a theoretical and experimental basis for the application of nanocomposite metamaterials in other wavebands. |
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