Broadband solar absorber based on titanium square ring structure array

Abstract

The solar absorber based on a titanium square ring structure array belongs to the field of micro-nano optoelectronic technology. It is composed of multiple adjustable structural units periodically arranged in the XOY plane. Sunlight is incident in the form of a plane wave. Each adjustable structural unit comprises, from bottom to top, a base layer of Ti material, a first buffer layer of Si3N4 material, a second buffer layer of TiN material, and an antenna made of Ti material. The base layer, the first buffer layer, and the second buffer layer are all square in shape. The antenna is in the shape of a square ring and is arranged above the center of the buffer layer. The side length of the square ring includes an angle of 45° with the X-axis and the Y-axis. The solar absorber has a simple structure and an average absorption rate of 95.9% within a broadband range of 280nm-2100nm. It is not affected by the polarization of the light source and has a good absorption effect within the incident angle range of 0° to 60°.

Description

Technical Field

[0001] The invention discloses a broadband solar absorber based on a titanium square ring structure array and belongs to the technical field of micro-nano optoelectronics. Background Art

[0002] Metamaterial absorbers can be engineered to efficiently absorb light energy and convert it into heat or other forms of energy through the design of metamaterial structures. Since 2008, when Landy et al. first proposed using metamaterials as perfect absorbers based on a metal-insulator-metal structure to achieve ultrahigh absorption within a narrow frequency range, metamaterial absorbers have been extensively studied. The applicable wavelengths of these absorbers have gradually expanded from microwaves to the terahertz, mid-infrared, near-infrared, and visible bands, and numerous applications have been proposed, including imaging, stealth, and solar cells.

[0003] Currently, the typical method to achieve broadband absorption is to arrange multiple metal resonators in a unit structure, because these resonators have different peak absorption positions. Broadband absorption is achieved by superimposing the absorption peaks generated by these different metal resonators. However, this method also has its limitations. Due to the competition effect between different resonators, the number of resonators is limited. In addition, noble metals are widely used to manufacture various absorbers due to their plasmon resonance and light coupling properties. However, the high cost and low natural reserves of noble metals are not suitable for large-scale processing. Refractory metals have become a better choice due to their low cost, high melting point, and large imaginary part of the dielectric constant, which can cause high light absorption in a broadband range. In recent years, a wide variety of solar absorbers have been gradually designed by scholars from various countries, but most absorbers have some shortcomings, such as poor broadband performance, low absorptivity, or the absorption bandwidth cannot match the energy distribution of the solar spectrum, resulting in low absorption effect. Summary of the Invention

[0004] In order to efficiently utilize solar energy, the present invention designs a solar absorber based on a titanium square ring structure array. The solar absorber has a simple structure and an average absorption rate of 95.9% in the broadband range of 280nm-2100nm. It is not affected by the polarization of the light source and has a good absorption effect in the incident angle range of 0° to 60°.

[0005] The object of the present invention is achieved like this:

[0006] A broadband solar absorber based on a titanium square ring structure array is composed of multiple adjustable structural units periodically arranged in the XOY plane. Sunlight is incident in the form of a plane wave. Each adjustable structural unit is composed of a base layer of Ti material, a first buffer layer of Si3N4 material, a second buffer layer of TiN material, and an antenna of Ti material from bottom to top. The base layer, the first buffer layer, and the second buffer layer are all square in shape. The antenna is in the shape of a square ring and is arranged above the center of the buffer layer. The side length of the square ring is at an angle of 45° with the X-axis and the Y-axis.

[0007] The relative positions of the base layer, the first buffer layer, the second buffer layer and the antenna are defined as follows: the plane where the base layer is located is the XOY plane, that is, the horizontal plane, the center position of the base layer coincides with the coordinate origin, the two sets of opposite sides of the base layer are parallel to the X-axis and the Y-axis respectively, the first buffer layer and the second buffer layer have the same shape, size and placement direction as the base layer, and the center position of the square ring of the antenna coincides with the coordinate origin.

[0008] The above-mentioned solar absorber based on the titanium square ring structure array has the following dimensions: the base layer has a size of 0.5μm×0.5μm×0.16μm; the first buffer layer has a size of 0.5μm×0.5μm×0.07μm; the second buffer layer has a size of 0.5μm×0.5μm×0.14μm; the height of the antenna is D=0.315μm, the outer side length of the square ring is L1=0.31μm, and the inner side length is L2=0.25μm.

[0009] Beneficial effects:

[0010] First, the solar absorber based on the square ring structure array of the present invention has only four layers: a base layer, a first buffer layer, a second buffer layer, and an antenna. The shapes are only square and square ring, which makes it simple in structure and easy to process and manufacture.

[0011] Second, the solar absorber based on the square ring structure array of the present invention has an average absorptivity of 95.9% in the broadband range of 280nm-2100nm;

[0012] Third, the solar absorber based on the square ring structure array of the present invention is not affected by the polarization of the light source and has a good absorption effect within the incident angle range of 0° to 60°;

[0013] Fourthly, the solar energy absorber based on the square ring structure array of the present invention has a solar heat conversion efficiency exceeding 90% within a temperature range of 100° C. to 900° C. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the three-dimensional structure of the solar absorber based on the square ring structure array of the present invention.

[0015] Figure 2 Schematic diagram of the three-dimensional structure of a single controllable structural unit.

[0016] Figure 3 Schematic diagram of the relative positions of the base layer, the first buffer layer, the second buffer layer and the antenna.

[0017] Figure 4 This is a screenshot of the simulation software interface of the present invention.

[0018] Figure 5 for Figure 4 Absorption effect curve in .

[0019] Figure 6 This is the curve showing the effect of the height change of the superstructure on the absorption rate.

[0020] Figure 7 This is the curve showing how the change in the outer side length of the square ring structure affects the absorption rate.

[0021] Figure 8 This is the curve showing the effect of changes in the incident angle of sunlight on the absorptivity.

[0022] Figure 9 This is the curve of the influence of the change of sunlight polarization angle on the absorption rate.

[0023] Figure 10 This is the curve showing the effect of temperature and concentration factor changes on thermal conversion efficiency.

[0024] In the figure: 1 base layer, 2 first buffer layer, 3 second buffer layer, 4 antenna. DETAILED DESCRIPTION

[0025] The specific embodiments of the present invention are described in further detail below with reference to the accompanying drawings. Specific implementation method 1

[0027] The solar absorber based on the square ring structure array in this specific embodiment is composed of multiple adjustable structural units arranged periodically in the XOY plane. The sunlight is incident in the form of a plane wave, such as Figure 1 As shown, each of the adjustable structural units is composed of a base layer 1 of Ti material, a first buffer layer 2 of Si3N4 material, a second buffer layer 3 of TiN material, and an antenna 4 of Ti material from bottom to top; the base layer 1, the first buffer layer 2, and the second buffer layer 3 are all square in shape, and the antenna 4 is in the shape of a square ring, which is arranged above the center of the buffer layer 3, and the side length of the square ring is at an angle of 45° with the X-axis and the Y-axis, as shown in FIG. Figure 2 As shown;

[0028] The relative positions of the base layer 1, the first buffer layer 2, the second buffer layer 3 and the antenna 4 are defined as follows: the plane where the base layer 1 is located is the XOY plane, that is, the horizontal plane, the center position of the base layer 1 coincides with the coordinate origin, the two sets of opposite sides of the base layer 1 are parallel to the X-axis and the Y-axis, respectively, the first buffer layer 2 and the second buffer layer 3 have the same shape, size and placement direction as the base layer 1, and the center position of the square ring of the antenna 4 coincides with the coordinate origin. Specific implementation method 2

[0030] The solar absorber based on the square ring structure array under this specific embodiment, on the basis of specific embodiment one, further limits the size of the base layer 1 to 0.5μm×0.5μm×0.16μm; the size of the first buffer layer 2 is 0.5μm×0.5μm×0.07μm; the size of the second buffer layer 3 is 0.5μm×0.5μm×0.14μm; the height of the antenna 4 is D=0.315μm, the outer side length of the square ring is L1=0.31μm, and the inner side length is L2=0.25μm. Specific implementation method three

[0032] The solar absorber based on the square ring structure array in this specific embodiment uses FDTD-Solutions software to simulate the effect of the height change of the structure in the antenna 4 on the absorption rate on the basis of the specific embodiment 2. The simulation interface is as follows: Figure 4 As shown, Figure 4 The absorption effect curve in Figure 5 As shown, and using:

[0033]

[0034] Where A is the average absorptivity of the absorber, λ is the wavelength of the incident light, λmax is the maximum value within the wavelength range of the incident light source, and λmin is the minimum value within the wavelength range of the incident light source. A is a function of the absorber's absorber strength as a function of the wavelength of the incident light.

[0035] The average absorption rate can be calculated from the above formula to be 95.9%;

[0036] When the antenna height changes from 0.295μm to 0.335μm, the absorption rate curve is as follows Figure 6As shown, the simulation results show that when the height is relatively small, the absorption bandwidth is not ideal. As the height increases, the continuous absorption spectrum with an absorptivity higher than 90% appears concave at 0.6μm to 1.4μm, and a new high-absorption rate part appears at the long wavelength. By comparison, it is found that when the antenna height of the absorber changes, the absorption bandwidth and absorptivity will be affected, resulting in a decrease in the absorption effect of the absorber, which further proves the rationality of the parameters of the solar absorber based on the square ring structure array of the present invention. Specific implementation method four

[0038] The solar absorber based on the square ring structure array in this specific embodiment is based on the specific embodiment 2. The effect of the change in the outer side length of the square ring structure in the antenna 4 on the absorption rate is simulated and tested. When the side length changes from 0.29 μm to 0.33 μm, the absorption rate curve is as follows: Figure 7 As shown, the simulation results show that when the side length is shorter, the absorption bandwidth is significantly reduced. As the length increases, the continuous absorption spectrum with an absorptivity higher than 90% appears concave at the position of 0.6μm to 1.2μm, and a new high absorption rate part appears at the long wavelength. By comparing the absorption spectra of the set parameters with other parameters, it is found that when the side length of the square ring structure antenna in the absorber changes, the absorption bandwidth of the absorber will not be consistent with the band where the energy of solar energy is more concentrated, resulting in a decrease in the absorption effect of the absorber, which further proves the rationality of the parameters of the solar absorber based on the square ring structure array of the present invention. Specific implementation method five

[0040] The solar absorber based on the square ring structure array in this specific embodiment is based on the specific embodiment 2, and the influence of the angle change of the incident sunlight on the absorption rate is simulated and tested at the incident angles of 0°, 10°, 20°, 30°, 40°, 50°, and 60°, as shown in FIG. Figure 8 As shown, the simulation results show that when the incident angle is less than 50°, the absorption rate curve at the short wavelength does not change significantly, and the absorption rate at the long wavelength decreases slightly; when the incident angle is greater than 50°, the absorption peaks at the short wavelength and the long wavelength both show a slightly reduced absorption rate. In short, the absorber has a good absorption effect within the incident angle range of 0° to 60°, which shows that the solar absorber based on the square ring structure array of the present invention has good wide-angle absorption performance. Specific implementation method six

[0042] The solar absorber based on the square ring structure array in this specific embodiment is based on the specific embodiment 2, and the influence of the change of the polarization angle of sunlight on the absorption rate is simulated and tested under the conditions of 0°, 15°, 30°, 45°, 60°, 75° and 90° polarization angles. Figure 9As shown in the figure, the simulation results show that the absorptivity curve of the absorber does not change when the polarization angle of the light source is changed, and the overall performance is polarization insensitive. Specific embodiment seven

[0044] In this embodiment, based on the second embodiment, the solar thermal conversion efficiency of the square ring array solar absorber was calculated at a temperature range of 100°C to 900°C under the conditions of concentration factors C = 10, C = 100, and C = 1000. According to the energy balance equation, η can be calculated as follows:

[0045]

[0046]

[0047]

[0048] Where G represents the total incident irradiance, which can be expressed as G = C × 1000 W / m 2 To calculate, C represents the concentration coefficient of solar irradiance, σ represents the Stefan-Boltzmann constant, T w Indicates the operating temperature of the absorber, and T0 is set to 0℃. B (λ,T w ) represents the operating temperature T w Blackbody radiation under Figure 10 As shown, the calculation results show that the absorber can achieve high light-to-heat conversion efficiency, indicating that it is suitable for use in solar photovoltaic systems.

Claims

1. A broadband solar absorber based on a titanium square ring structure array, comprising a plurality of adjustable structural units periodically arranged in an XOY plane, wherein sunlight is incident in the form of a plane wave, and each adjustable structural unit comprises, from bottom to top, a base layer (1), a first buffer layer (2), a second buffer layer (3), and an antenna (4) made of a Ti material; the base layer (1), the first buffer layer (2), and the second buffer layer (3) are all square in shape, and the antenna (4) is in the shape of a square ring and is arranged above the center of the buffer layer (3); The relative positions of the base layer (1), the first buffer layer (2), the second buffer layer (3) and the antenna (4) are defined as follows: the plane where the base layer (1) is located is the XOY plane, that is, the horizontal plane; the center position of the base layer (1) coincides with the coordinate origin; the two sets of opposite sides of the base layer (1) are parallel to the X axis and the Y axis respectively; the first buffer layer (2) and the second buffer layer (3) have the same shape, size and placement direction as the base layer (1); and the center position of the square ring of the antenna (4) coincides with the coordinate origin. It is characterized by: The base layer (1) is made of Ti material, the first buffer layer (2) is made of Si3N4 material, and the second buffer layer (3) is made of TiN material; the side length of the square ring forms an angle of 45° with the X-axis and the Y-axis; the height of the antenna (4) is D=0.315 μm, the outer side length of the square ring is L1=0.31 μm, and the inner side length is L2=0.25 μm.

2. The solar absorber based on the titanium square ring structure array according to claim 1, characterized in that: The size of the base layer (1) is 0.5 μm×0.5 μm×0.16 μm; the size of the first buffer layer (2) is 0.5 μm×0.5 μm×0.07 μm; and the size of the second buffer layer (3) is 0.5 μm×0.5 μm×0.14 μm.

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