Selective high-absorption solar absorber based on double-layer elliptical structure

Abstract

The invention relates to the technical field of micro-nano optical devices, in particular to a selective high-absorption solar absorber based on a double-layer elliptical structure, which consists of a plurality of selective high-absorption absorber unit structure periodic arrays, each selective high-absorption absorber unit structure comprises an upper-layer elliptical disk array structure, a middle dielectric layer, a lower-layer square array structure and a metal tungsten substrate, and a local surface plasmon resonance mode can be generated between a metal layer and the dielectric layer through the upper-layer elliptical disk array structure; the built-in square array structure in the metal tungsten substrate can generate a Fabry-Perot resonance mode, high absorption of a target wave band, namely a wave band where solar radiation is located, can be further improved through coupling of multiple modes generated by the lower layer and the upper layer, meanwhile, the absorption rate of a long wave band can be restrained, and selective absorption is achieved. The selective high-absorption solar absorber based on the double-layer elliptical structure has potential application value in the fields of thermophotovoltaic power generation, solar photo-thermal conversion and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-nano optical devices, and particularly to a highly selective absorbing solar absorber based on a double-layer elliptical structure. Background Art

[0002] Under the background of the global energy structure transformation, the continuous consumption of traditional fossil fuels is driving the innovation of renewable energy technologies. As an almost inexhaustible clean energy source, solar energy has attracted extensive attention. Metamaterials are artificial engineering materials containing sub-wavelength structures. Micro-nano sized metamaterial absorbers are often used to absorb solar radiation energy. During the application of solar absorbers, they often work in a high-temperature environment of 1000K to 1500K. In this temperature environment, while the absorber absorbs solar energy, it will also generate a large amount of thermal radiation loss by itself, thereby reducing the absorption effect of the absorber.

[0003] Currently, most solar absorbers use a single-layer structure, and achieve a high absorption effect by regulating the modes generated by periodic nanoparticles on the substrate. The mode regulation effect is relatively single, and the thermal radiation loss generated by the absorber is ignored, resulting in a reduction in the absorption effect of the absorber.

[0004] Therefore, in order to absorb energy in the solar spectrum band and maintain a low absorption rate in other bands, it is necessary to design a highly selective absorbing solar absorber. Summary of the Invention

[0005] The purpose of the present invention is to provide a highly selective absorbing solar absorber based on a double-layer elliptical structure, aiming to solve the technical problems of low absorption rate and high thermal radiation loss of most existing solar absorbers.

[0006] To achieve the above purpose, the present invention provides a highly selective absorbing solar absorber based on a double-layer elliptical structure. The metamaterial selective solar absorber based on the double-layer elliptical structure is composed of a periodic array of multiple highly selective absorbing absorber unit structures. Each highly selective absorbing absorber unit structure includes an upper elliptical disk array structure, an intermediate dielectric layer, a lower square array structure, and a tungsten metal substrate. The upper elliptical disk array structure, the intermediate dielectric layer, the lower square array structure, and the tungsten metal substrate are arranged in sequence from top to bottom;

[0007] The upper elliptical disk array structure is composed of 4 groups of elliptical disk units. The lower square array structure is arranged in the tungsten metal substrate. The upper surface of the lower square array structure is coplanar with the upper surface of the tungsten metal substrate and is fixedly connected to the lower surface of the intermediate dielectric layer.

[0008] Among them, the range of the period P of the selective high-absorption solar absorber unit structure is 300-400 nm.

[0009] Among them, the centers of the lower-layer square array structure, the metal tungsten substrate, and the upper-layer elliptical disk array structure are coaxial. The range of the side length D of the lower-layer square array structure is 150-250 nm, the thickness value h1 ranges from 300 to 400 nm, and the filling material is aluminum oxide.

[0010] Among them, the thickness value h2 of the intermediate dielectric layer ranges from 35 to 55 nm, and the material is aluminum oxide.

[0011] Among them, the upper-layer elliptical disk array structure is composed of 4 completely identical elliptical disk units located on the diagonal. The range of the long semi-axis a of the elliptical disk unit is 70-90 nm, and the range of the short semi-axis b is 15-35 nm.

[0012] Among them, in the horizontal direction, the range of the center distance d1 between two adjacent elliptical disk units in the upper-layer elliptical disk array structure is 150-190 nm, and the range of the center distance d2 between two adjacent elliptical disk units in the diagonal direction is 220-260 nm.

[0013] Among them, in the vertical direction, the upper-layer elliptical disk unit structure is provided with a layered structure composed of alternating aluminum oxide and tungsten, arranged in the direction away from the intermediate dielectric layer. The thickness h3 of the first layer ranges from 40 to 50 nm, the material is tungsten, the thickness h4 of the second layer ranges from 35 to 45 nm, the material is aluminum oxide, the thickness h5 of the third layer ranges from 20 to 30 nm, the material is tungsten, and the thickness h6 of the fourth layer ranges from 50 to 60 nm, the material is aluminum oxide.

[0014] The present invention provides a selective high-absorption solar absorber based on a double-layer elliptical structure, which is composed of a periodic array of multiple selective high-absorption absorber unit structures. Each selective high-absorption absorber unit structure includes an upper-layer elliptical disk array structure, an intermediate dielectric layer, a lower-layer square array structure, and a metal tungsten substrate.

[0015] Compared with the prior art, the advantages of the present invention are as follows: through the upper-layer elliptical disk array structure, a local surface plasmon resonance mode can be generated between the metal layer and the dielectric layer. The square array structure built in the metal tungsten substrate can generate a Fabry-Perot resonance mode. Through the coupling of multiple modes generated by the lower layer and the upper layer, the high absorption in the target band, that is, the solar radiation band, can be further improved. At the same time, the absorption rate in the long wave band can also be suppressed, realizing selective absorption and reducing the thermal radiation loss of the absorber. Description of the Drawings

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0017] Figure 1 It is a schematic structural diagram of a selective high-absorption solar absorber based on a double-layer elliptical structure of the present invention.

[0018] Figure 2 It is a schematic diagram of the horizontal dimension of a selective high-absorption solar absorber based on a double-layer elliptical structure of the present invention.

[0019] Figure 3 It is a schematic diagram of the vertical dimension of a selective high-absorption solar absorber based on a double-layer elliptical structure of the present invention.

[0020] Figure 4 It is the absorption spectrum diagram of the specific embodiment of the present invention.

[0021] 1 - upper elliptical disk array structure, 2 - intermediate dielectric layer, 3 - lower square array structure, 4 - tungsten metal substrate. Specific Embodiments

[0022] The following will describe in detail the embodiments of the present invention. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as a limitation to the present invention.

[0023] Please refer to Figures 1 to 3 , the present invention provides a selective high-absorption solar absorber based on a double-layer elliptical structure, including an upper elliptical disk array structure 1, an intermediate dielectric layer 2, a lower square array structure 3, and a tungsten metal substrate 4. The upper elliptical disk array structure 1, the intermediate dielectric layer 2, the lower square array structure 3, and the tungsten metal substrate 4 are arranged in sequence from top to bottom;

[0024] The upper elliptical disk array structure is composed of 4 groups of elliptical disk units. The lower square array structure is arranged in the tungsten metal substrate. The upper surface of the lower square array structure is coplanar with the upper surface of the tungsten metal substrate and is fixedly connected to the lower surface of the intermediate dielectric layer.

[0025] The range of the period P of the unit structure of the selective high-absorption solar absorber is 300 - 400 nm.

[0026] The centers of the lower-layer square array structure, the tungsten metal substrate, and the upper-layer elliptical disk array structure are coaxial. The range of the side length D of the lower-layer square array structure is 150 - 250 nm, and the range of the thickness value h1 is 300 - 400 nm. The filling material is aluminum oxide.

[0027] The range of the thickness value h2 of the intermediate dielectric layer is 35 - 55 nm, and the material is aluminum oxide.

[0028] The upper-layer elliptical disk array structure is composed of 4 completely identical elliptical disk units located on the diagonal. The range of the major semi-axis a of the elliptical disk unit is 70 - 90 nm, and the range of the minor semi-axis b is 15 - 35 nm.

[0029] In the upper-layer elliptical disk array structure, the range of the center distance d1 between two adjacent elliptical disk units in the horizontal direction is 150 - 190 nm, and the range of the center distance d2 between two adjacent elliptical disk units in the diagonal direction is 220 - 260 nm.

[0030] In the vertical direction, the upper-layer elliptical disk unit structure is provided with a layered structure composed of alternating aluminum oxide and tungsten, arranged in the direction away from the intermediate dielectric layer. The range of the thickness h3 of the first layer is 40 - 50 nm, and the material is tungsten. The range of the thickness h4 of the second layer is 35 - 45 nm, and the material is aluminum oxide. The range of the thickness h5 of the third layer is 20 - 30 nm, and the material is tungsten. The range of the thickness h6 of the fourth layer is 50 - 60 nm, and the material is aluminum oxide.

[0031] In this embodiment, through the upper-layer elliptical disk array structure 1, a local surface plasmon resonance mode can be generated between the metal layer and the dielectric layer, and a resonance mode will also be generated with the intermediate dielectric layer 2. The square array structure 3 built in the tungsten metal substrate 4 can generate a Fabry - Perot resonance mode. By coupling the multiple modes generated by the lower layer and the upper layer, the high absorption in the target band, that is, the band where solar radiation is located, can be further improved, and at the same time, the absorption rate in the long wavelength band can be suppressed to achieve selective absorption.

[0032] Furthermore, the present invention also provides a specific embodiment, which is illustrated by simulation experiments using the finite - difference time - domain method and setting corresponding boundary conditions.

[0033] Specifically, in the setting of periodic boundaries, periodic boundary conditions are adopted in the x and y directions, and a perfectly matched layer boundary condition is adopted in the z direction. For the incident light source, a TM - polarized plane wave is used as the incident light source and is incident perpendicularly to the surface of the upper - layer elliptical disk array structure 1.

[0034] Among them, the period P of the selective high absorption solar absorber unit structure is 340nm, and the lower square array structure 3 is introduced into the metal tungsten substrate 4, wherein the side length width D of the lower square array structure 3 is 210nm, the thickness value h1 is 340, and the filling material is aluminum oxide. The thickness value h2 of the intermediate dielectric layer on the upper surface of the lower square array structure 3 is 45nm, and the material is aluminum oxide. The upper elliptical disk array structure 1 is composed of 4 completely identical elliptical disk units located on the diagonal, the major semi-axis a of the elliptical disk unit is 80nm, and the minor semi-axis b is 25nm. For the upper elliptical disk array structure, the center distance between two adjacent elliptical disk units in the horizontal direction is d1=170nm, and the center distance between two adjacent elliptical disk units in the diagonal direction is d2=240nm.

[0035] In the vertical direction, the upper elliptical disk unit structure is provided with layers composed of alternating aluminum oxide and tungsten, arranged in a direction away from the intermediate dielectric layer, the first layer has a thickness of h3 = 45nm, the material is tungsten, the second layer has a thickness of h4 = 40nm, the material is aluminum oxide, the third layer has a thickness of h5 = 25nm, the material is tungsten, the fourth layer has a thickness of h6 in the range of 55nm, the material is aluminum oxide, and the dielectric constants of metal tungsten and aluminum oxide adopt the model in the Palik manual.

[0036] In this practical example, a metal tungsten substrate 4 is first prepared using PECVD deposition technology; then a square cavity is prepared on the metal tungsten substrate 4 using photolithography technology and etching technology, and the PECVD deposition technology is used to fill the aluminum oxide material to obtain a lower square array structure 3, and then the PECVD deposition technology is used to prepare the aluminum oxide film 2; then the PECVD deposition technology is continued to be used to prepare a four-layer thin film structure of tungsten (w)-aluminum oxide (Al2O3)-tungsten (w)-aluminum oxide (Al2O3), and then the photolithography technology and etching technology are used to prepare the upper elliptical disk array structure 1.

[0037] According to the absorption spectrum obtained by numerical simulation, Figure 4 As shown, the present invention obtains four absorption peaks at wavelengths of 459nm, 796nm, 1214nm and 1642nm, all of which have an absorption rate of more than 98%. It can be calculated that the total absorption rate of the absorber to AM1.5 solar radiation in the range of 280-4000nm is 0.9635.

[0038] What is disclosed above is only a preferred embodiment of the present invention, and it certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A selective high-absorption solar absorber based on a double-layer elliptical structure, characterized in that the metamaterial selective solar absorber based on the double-layer elliptical structure is composed of a periodic array of multiple selective high-absorption absorber unit structures. Each selective high-absorption absorber unit structure includes an upper elliptical disk array structure, an intermediate dielectric layer, a lower square array structure, and a tungsten metal substrate. The upper elliptical disk array structure, the intermediate dielectric layer, the lower square array structure, and the tungsten metal substrate are arranged in sequence from top to bottom; the upper elliptical disk array structure is composed of 4 groups of elliptical disk units. The lower square array structure is arranged inside the tungsten metal substrate. The upper surface of the lower square array structure is coplanar with the upper surface of the tungsten metal substrate and is fixedly connected to the lower surface of the intermediate dielectric layer.

2. The selective high-absorption solar absorber based on the double-layer elliptical structure according to claim 1, characterized in that the range of the period P of the selective high-absorption solar absorber unit structure is 300 - 400 nm.

3. The selective high-absorption solar absorber based on the double-layer elliptical structure according to claim 2, characterized in that the centers of the lower square array structure, the tungsten metal substrate, and the upper elliptical disk array structure are coaxial. The range of the side length D of the lower square array structure is 150 - 250 nm, the thickness value h1 ranges from 300 - 400 nm, and the filling material is aluminum oxide.

4. The selective high-absorption solar absorber based on the double-layer elliptical structure according to claim 3, characterized in that the range of the thickness value h2 of the intermediate dielectric layer is 35 - 55 nm, and the material is aluminum oxide.

5. The selective high-absorption solar absorber based on the double-layer elliptical structure according to claim 4, characterized in that the upper elliptical disk array structure is composed of 4 identical elliptical disk units located on the diagonal. The range of the long semi-axis a of the elliptical disk unit is 70 - 90 nm, and the range of the short semi-axis b is 15 - 35 nm.

6. The selective high-absorption solar absorber based on the double-layer elliptical structure according to claim 5, characterized in that in the horizontal direction, the range of the center distance d1 between two adjacent elliptical disk units of the upper elliptical disk array structure is 150 - 190 nm, and in the diagonal direction, the range of the center distance d2 between two adjacent oblique elliptical disk units is 220 - 260 nm.

7. The selective high-absorption solar absorber based on the double-layer elliptical structure according to claim 6, characterized in that in the vertical direction, the upper elliptical disk unit structure is provided with a layer composed of alternating aluminum oxide and tungsten, arranged in the direction away from the intermediate dielectric layer. The thickness h3 of the first layer ranges from 40 - 50 nm, the material is tungsten, the thickness h4 of the second layer ranges from 35 - 45 nm, the material is aluminum oxide, the thickness h5 of the third layer ranges from 20 - 30 nm, the material is tungsten, and the thickness h6 of the fourth layer ranges from 50 - 60 nm, the material is aluminum oxide.

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