Research On Photothermal Selective Surface Absorber Based On MIM Structure

Photothermal selective absorbers are functional optical devices that can convert light energy into thermal energy.Compared with other common forms of solar energy conversion such as photovoltaic,photochemical,and photobiological energy,solar photothermal conversion is the most direct and effective way for people to utilize solar energy,which has broad application prospects in fields such as solar hot water utilization,solar seawater desalination,thermochemical utilization,and solar photothermal power generation.The solar radiation energy is mainly concentrated in the ultraviolet near-infrared band(0.3-2.5 μm),cccounting for 98% of the total solar radiation energy;while in the mid to far infrared band(2.5-50 μm),objects radiate energy due to blackbody radiation.Therefore,the study of solar selective absorbers is of great significance,which has a high absorption rate between 0.3 and 2.5 μm and has low emissivity ranging from 2.5 to 50 μm.This thesis designed three types of photothermal selective absorbers,named "Tian" shaped,"Go like" shaped,and circular hole shaped.Through structural design,the surface plasmon resonance effect,Fabry-Perot resonance effect,and quarter wavelength resonance effect were synergistically applied to achieve a solar absorber with a high absorption rate ranging from 0.3 to 2.5 μm;And reduce the infrared emissivity between 2.5 and 50 μm by constructing a pore structure that is much smaller than the mid to far infrared wavelength.The average absorption rates of the "Tian" character,"Go like" shape,and circular hole structure in the absorption zone all exceed 90%,which are 98.15%,95.14%,and 94.16%,respectively.The effective absorption bands of all three structures cover 0.3-2 μm.Among them,"Go like" structure has the widest effective absorption bandwidth,covering 0.3 to 2.34 μm.Meanwhile,the circular hole structure can form a steep absorption limit in the transition region between absorption and radiation frequency domains,having better selective absorption characteristics.On this basis,the periodic microsphere array was prepared by using the self-assembly effect of polystyrene(PS)microsphere,and the circular hole structure photothermal selective absorber was fabricated using the periodic microsphere array as the template.The size of absorber unit prepared with PS microspheres as template reaches nanometer level,which not only breaks through the limitation of UV lithography accuracy,but also overcomes the difficulty of high production cost of the Electron beam lithography system,providing a solid theoretical and experimental basis for the research of photothermal selective absorbers.