Solar absorber based on cross-shaped structure array

Abstract

The solar absorber based on the cross-shaped structure array of the present invention belongs to the field of micro-nano optoelectronic technology; it is composed of multiple adjustable structural units arranged periodically in the XOY plane, and sunlight is incident in the form of a plane wave. Each adjustable structural unit consists of a base layer, a buffer layer and an antenna from bottom to top; the base layer and the buffer layer are square in shape, and the shape of the antenna includes a regular cross structure arranged in the middle of the buffer layer and a T-shaped structure arranged at the edge of the buffer layer. Two adjustable structural units are arranged together, and two adjacent T-shaped structures form a non-regular cross structure; the antenna includes an upper structure made of SiN4 and a lower structure made of W, and the upper and lower structures have the same shape, size and placement direction; the present invention has a simple structure, an average absorption rate of 94.1% in the broadband range of 584.2nm-2802.1nm, and is not affected by the polarization of the light source. It has a good absorption effect in the incident angle range of 0° to 60°.

Description

Technical Field

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

[0002] A metasurface is an artificially designed periodically arranged structure. Because of its special electromagnetic properties, adjustable refractive index, asymmetric transmission and other characteristics, it is often used to prepare high-efficiency electromagnetic wave absorbers.

[0003] Nowadays, there are many technologies, such as photovoltaics, solar energy and thermal generators, which can convert solar energy into other forms of energy, such as light energy, heat energy or electricity, and apply them to other applications. Therefore, how to efficiently utilize solar energy has become a major research topic.

[0004] Currently, the typical approach to achieving broadband absorption is to arrange multiple metal resonators in a cellular structure, as these resonators have different peak absorption positions. Broadband absorption is achieved by superimposing the absorption peaks generated by these different metal resonators. However, this approach also has its limitations. Due to the competition 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 make them unsuitable for large-scale processing, so a more common method for preparing absorbers is needed. Since the metal-insulator-metal structure was proposed in 2008, metamaterials have been used to develop narrowband or broadband absorbers. In recent years, a wide variety of solar metastructure absorbers have been gradually designed by researchers from various countries. However, 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

[0005] In order to efficiently utilize solar energy, the present invention designs a solar absorber based on a cross-shaped structure array. The solar absorber has a simple structure and an average absorption rate of 94.1% in the broadband range of 584.2nm-2802.1nm. 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°.

[0006] The object of the present invention is achieved like this:

[0007] A solar absorber based on a cross-shaped structure array is composed of multiple adjustable structural units arranged periodically in an 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 buffer layer of SiO2 material, and an antenna from bottom to top. The base layer and the buffer layer are square in shape. The antenna includes a regular cross structure arranged in the middle of the buffer layer and a T-shaped structure arranged at the edge of the buffer layer. Two adjustable structural units are arranged together, and two adjacent T-shaped structures form a non-regular cross structure. The antenna includes an upper structure made of SiN4 and a lower structure made of W. The upper and lower structures have the same shape, size, and placement direction.

[0008] The relative positions of the base layer, buffer layer and 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 buffer layer and the base layer have the same shape, size and placement direction, in the right cross structure of the antenna, the horizontal and vertical directions are parallel to the X axis and the Y axis, respectively, in the T-shaped structure of the antenna, the horizontal direction coincides with the boundary of the buffer layer, and the intersection of the horizontal and vertical directions is located at the center of the boundary of the buffer layer.

[0009] The above-mentioned solar absorber based on the cross-shaped structure array has a size of 0.4μm×0.4μm×0.5μm for the base layer; a size of 0.4μm×0.4μm×0.045μm for the buffer layer; a height of the upper structure and the lower structure of the upper antenna is D1=0.1μm; in the regular cross-shaped structure, the horizontal and vertical lengths are both L=0.7μm, and the widths are both W=0.08μm; in the T-shaped structure, the horizontal length is L=0.6μm, the width is W=0.08μm, the vertical length is W=0.09μm, and the width is W=0.04μm.

[0010] Beneficial effects:

[0011] First, the solar absorber based on the cross-shaped structure array of the present invention has only three layers: base layer, buffer layer and antenna, and the shapes are only square, cross and T-shaped, with a simple structure.

[0012] Second, the solar absorber based on the cross-shaped structure array of the present invention has an average absorptivity of 94.1% in the broadband range of 584.2nm-2802.1nm;

[0013] Third, the solar absorber based on the cross-shaped 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 50°. 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 cross-shaped 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, buffer layer and 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 height changes of the upper and lower structures on the absorption rate.

[0020] Figure 7 This is the curve showing the effect of changes in horizontal and vertical lengths on the absorption rate in a regular cross structure.

[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] In the figure: 1 base layer, 2 buffer layer, 3 antenna, 3-1 upper structure, 3-2 lower structure. DETAILED DESCRIPTION

[0024] The specific embodiments of the present invention are described in further detail below with reference to the accompanying drawings. Specific implementation method 1

[0026] The solar absorber based on the cross-shaped 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 buffer layer 2 of SiO2 material and an antenna 3 from bottom to top; the base layer 1 and the buffer layer 2 are square in shape, and the shape of the antenna 3 includes a right cross structure arranged in the middle of the buffer layer 2 and a T-shaped structure arranged at the edge of the buffer layer 2. Two adjustable structural units are arranged together, and two adjacent T-shaped structures form a non-right cross structure; the antenna 3 includes an upper structure 3-1 of Si3N4 material and a lower structure 3-2 of W material. The upper structure 3-1 and the lower structure 3-2 have the same shape, size and placement direction, as shown in FIG. Figure 2 As shown;

[0027] The relative positions of the base layer 1, the buffer layer 2 and the antenna 3 are defined as follows: Figure 3 As shown: 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 buffer layer 2 has the same shape, size and placement direction as the base layer 1, in the right cross structure of the antenna 3, the horizontal and vertical directions are parallel to the X-axis and the Y-axis respectively, in the T-shaped structure of the antenna 3, the horizontal direction coincides with the boundary of the buffer layer 2, and the intersection of the horizontal and vertical directions is located at the boundary center of the buffer layer 2. Specific implementation method 2

[0029] The solar absorber based on the cross-shaped structure array in this embodiment further defines the sizes of the base layer 1, the buffer layer 2 and the antenna 3 on the basis of the embodiment 1, such as Figure 3 As shown, the size of the base layer 1 is 0.4μm×0.4μm×0.5μm; the size of the buffer layer 2 is 0.4μm×0.4μm×0.045μm; the heights of the upper structure 3-1 and the lower structure 3-2 of the upper antenna 3 are both D1=0.1μm. In the regular cross structure, the horizontal and vertical lengths are both L1=0.17μm, and the widths are both W1=0.08μm. In the T-shaped structure, the horizontal length is L2=0.26μm, the width is W1=0.08μm, the vertical length is W2=0.09μm, and the width is W3=0.04μm. Specific implementation method three

[0031] The solar absorber based on the cross-shaped structure array in this specific embodiment is based on the specific embodiment 2. The FDTD-Solutions software is used to simulate the effect of the height change of the upper structure 3-1 and the lower structure 3-2 in the antenna 3 on the absorption rate. The simulation interface is as follows: Figure 4 As shown, Figure 4 The absorption effect curve in Figure 5 As shown, and using:

[0032]

[0033] in, is the average absorptivity of the absorber, A is the absorptivity of the absorber, which is a function of the wavelength λ of the incident light, λ is the wavelength of the incident light, max is the maximum value within the wavelength range of the incident light, λ min It is the minimum value within the wavelength range of the incident light;

[0034] The average absorption rate can be calculated by the above formula to be 94.1%;

[0035] When the height changes from 0.06μm to 0.14μm, the absorption rate curve is as follows Figure 6 As shown, the simulation results show that as the height increases, the continuous absorption spectrum with an absorptivity higher than 90% appears concave at the position of 1.6μm to 2.0μm, and a new high absorptivity part appears at the long wavelength, indicating that when the antenna height of 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, further proving the rationality of the parameters of the solar absorber based on the cross-shaped structure array of the present invention. Specific implementation method four

[0037] The solar absorber based on the cross-shaped structure array in this specific embodiment is based on the specific embodiment 2. The effect of the change in the horizontal and vertical lengths of the cross-shaped structure in the antenna 3 on the absorption rate is simulated and tested. When the length changes from 0.15 μm to 0.19 μm, the absorption rate curve is as follows: Figure 7 As shown, the simulation results show that as the length increases, the continuous absorption spectrum with an absorptivity higher than 90% appears concave at the position of 1.4μm to 2.4μm, and a new high absorptivity part appears at the long wavelength, indicating that when the horizontal and vertical lengths of the cross-shaped structure antenna in the absorber change, 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 reduction in the absorption effect of the absorber, further proving the rationality of the parameters of the solar absorber based on the cross-shaped structure array of the present invention. Specific implementation method five

[0039] The solar absorber based on the cross-shaped structure array in this specific embodiment is based on the specific embodiment 2. The influence of the angle change of the incident sunlight on the absorption rate is simulated and tested at the incidence angles of 0°, 7°30′, 15°, 22°30′, 30°, 37°30′, 45°, 52°30′ and 60°, respectively. 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 both the short wavelength and the long wavelength begin to show a decrease in absorption rate, which indicates that the solar absorber based on the cross-shaped structure array of the present invention has good wide-angle absorption performance. Specific implementation method six

[0041] The solar absorber based on the cross-shaped 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 at the polarization angles of 0°, 15°, 30°, 45°, 90°, 75° and 90°, as shown in FIG. 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.

Claims

1. A solar absorber based on a cross-shaped structure array, comprising a plurality of adjustable structural units arranged periodically 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) of Ti material, a buffer layer (2) of SiO2 material, and an antenna (3); the base layer (1) and the buffer layer (2) are square in shape, and the antenna (3) comprises an upper structure (3-1) and a lower structure (3-2) of W material; The relative positions of the base layer (1), the buffer layer (2) and the antenna (3) 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 buffer layer (2) and the base layer (1) have the same shape, size and placement direction; It is characterized in that The shape of the antenna (3) includes a right cross structure arranged in the middle of the buffer layer (2) and a T-shaped structure arranged at the edge of the buffer layer (2), the two adjustable structural units are arranged together, and the two adjacent T-shaped structures form a non-right cross structure; the material of the upper structure (3-1) is Si3N4, and the upper structure (3-1) and the lower structure (3-2) have the same shape, size and placement direction; in the right cross structure in the antenna (3), the horizontal and vertical directions are parallel to the X axis and the Y axis respectively, and in the T-shaped structure in the antenna (3), the horizontal direction coincides with the boundary of the buffer layer (2), and the intersection of the horizontal and vertical directions is located at the boundary center of the buffer layer (2).

2. The solar absorber based on a cross-shaped structure array according to claim 1, characterized in that: The size of the base layer (1) is 0.4 μm×0.4 μm×0.5 μm; the size of the buffer layer (2) is 0.4 μm×0.4 μm×0.045 μm; the heights of the upper structure (3-1) and the lower structure (3-2) of the antenna (3) are both D1=0.1 μm, in the cross-shaped structure, the horizontal and vertical lengths are both L1=0.17 μm, and the widths are both W1=0.08 μm; in the T-shaped structure, the horizontal length is L2=0.26 μm, the width is W1=0.08 μm, the vertical length is W2=0.09 μm, and the width is W3=0.04 μm.

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