Solar absorber and processing method

Abstract

The invention discloses a solar absorber and a processing method, the solar absorber comprises a plurality of absorber units which are arranged in a periodic array, each absorber unit comprises a substrate layer, a dielectric layer, an ultrathin film layer and an antenna layer which are sequentially arranged from bottom to top, the antenna layer comprises a first antenna and four second antennas, and the first antenna and the second antennas are arranged in parallel. The projection of the first antenna on an XOY plane is in a cross shape, the projection of the second antennas on the XOY plane is in a square shape, the four second antennas are arranged in the four corners of the first antenna respectively, the projections of the substrate layer, the dielectric layer and the ultrathin film layer on the XOY plane are all in a square shape, the substrate layer is made of TiN materials, the dielectric layer is made of Al2O3 materials, and the ultrathin film layer is made of SiO2 materials. The ultrathin film layer is made of a TiN material, the first antenna is made of a Ni material, and the second antenna is made of a TiN material. The device has the advantages of simple structure, easiness in actual processing and production and good absorption effect.

Description

Technical Field

[0001] This invention relates to the field of micro-nano optoelectronics technology, and in particular to a solar energy absorber and its fabrication method. Background Technology

[0002] The majority of global energy comes from fossil fuels, and the excessive consumption of fossil fuels has led to an energy crisis with severe negative impacts on the environment, economy, and society. In contrast, solar energy is a highly attractive green and renewable energy source with advantages such as virtually unlimited capacity, complete cleanliness, and wide distribution. Fully utilizing solar energy can effectively alleviate the global energy crisis. Solar thermal conversion is the most common, direct, and effective method for collecting and utilizing solar energy, and the most critical component in a solar thermal conversion system is the solar absorber.

[0003] Plasmon absorbers have attracted considerable attention due to their unique property of capturing light in the subwavelength range. Numerous plasmon solar absorbers based on metal / insulator / metal metasurface structures can achieve single-wavelength or multi-band absorption spectra. However, the absorption bandwidth of these absorbers is typically narrow. The wavelength range of solar radiation at the Earth's surface is approximately 300 nm–2500 nm. The absorption band of a solar absorber must include or exceed this range, and within this range, the absorber's absorption performance should be as insensitive to polarized light as possible. One direct method to achieve broadband absorption is to stack multiple functional layers in the absorber configuration, allowing multiple resonant peaks in the absorption spectrum to overlap, thereby extending the absorption bandwidth. However, the broadband absorption is correspondingly limited due to the finite number of functional layers stacked in the configuration, and the fabrication process of such structures is typically complex and cumbersome. Noble metals are used in these ideal absorbers due to their strong optical coupling effect and plasmon resonance behavior. However, the further widespread application of most noble metals is still limited by their short absorption spectra, low storage capacity, and high cost. Therefore, designing and fabricating a high-efficiency solar absorber with a wide absorption bandwidth remains of great significance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a solar energy absorber with a simple structure, easy actual processing and production, wide absorption bandwidth, and good absorption effect.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A solar energy absorber includes multiple absorber units arranged in a periodic array. Each absorber unit comprises, from bottom to top, a substrate layer, a dielectric layer, an ultrathin film layer, and an antenna layer. The antenna layer includes a first antenna and four second antennas. The projection of the first antenna onto the XOY plane is cross-shaped, and the projection of the second antenna onto the XOY plane is square. The four second antennas are respectively arranged at the four corners of the first antenna. The projections of the substrate layer, dielectric layer, and ultrathin film layer onto the XOY plane are all square. The substrate layer is made of TiN material, the dielectric layer is made of Al2O3 material, the ultrathin film layer is made of TiN material, the first antenna is made of Ni material, and the second antennas are made of TiN material.

[0006] As a further improvement to the above technical solution: The first antenna has a length of 218 nm, a width of 20 nm, and a height of 190 nm.

[0007] The second antenna has a side length of 50nm and a height of 270nm.

[0008] The thickness of the substrate layer is 200 nm.

[0009] The thickness of the dielectric layer ranges from 140 nm to 260 nm.

[0010] The thickness of the dielectric layer is 200 nm.

[0011] The thickness of the ultrathin film layer is 5 nm.

[0012] The distance between the center of the first antenna and the center of the second antenna is nm.

[0013] The array period of the absorber unit is 250 nm.

[0014] A processing method based on the above-mentioned solar energy absorber includes the following steps: Step S1: Deposit the substrate layer, dielectric layer, and ultrathin film layer sequentially from bottom to top on the support material; Step S2: Spin-coat PMMA electron beam photoresist onto the ultrathin film layer; Step S3: Perform electron beam exposure and development of the cross pattern; Step S4: Deposit Ni; Step S5: Remove excess Ni to obtain a Ni cross structure; Step S6: Spin-coat PMMA electron beam photoresist again; Step S7: Deposit TiN; Step S8: Remove excess TiN to obtain a complete solar absorber structure.

[0015] Compared with the prior art, the advantages of the present invention are as follows: 1. The solar energy absorber of the present invention has a simple structure with only four layers stacked vertically, and each layer has only square and cross shapes. The Ni cross structure can be used as an alignment mark for standard electron beam overlay exposure process, which is easy to process and produce. The average absorption rate can reach 98.1% in a wide range of 300nm-2500nm, which can effectively cover the main energy distribution range of solar energy spectrum and has the advantages of wide absorption bandwidth and good absorption effect.

[0016] 2. The solar energy absorber of the present invention has a good absorption effect in the incident angle range of 0° to 60° and has good wide-angle absorption performance.

[0017] 3. The solar energy absorber of the present invention does not show a significant change in absorption rate when the polarization angle is changed, and the overall performance is polarization insensitive. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the solar energy absorber of the present invention.

[0019] Figure 2 This is a graph showing the absorption effect of the solar energy absorber of this invention.

[0020] Figure 3 This is a schematic diagram of the processing flow of the solar energy absorber of the present invention.

[0021] Figure 4 This is a distribution diagram of the electric and magnetic fields at different absorption peak wavelengths and positions in the solar energy absorber of this invention. Figure 4 a- Figure 4 d represents the electric field distribution at y=0 on the XZ plane for wavelengths of 402nm, 540nm, 886nm, and 1939nm, respectively. Figure 4 e- Figure 4 h represents the electric field distribution at y=43nm on the XZ plane for wavelengths of 402nm, 540nm, 886nm, and 193nm, respectively. Figure 4 i- Figure 4 l represents the magnetic field distribution at y=43nm on the XZ plane for wavelengths of 402nm, 540nm, 886nm, and 1939nm, respectively.

[0022] Figure 5 This is a graph showing the effect of the change in the height of the first antenna on the absorption rate in the solar energy absorber of this invention.

[0023] Figure 6 This is a graph showing the effect of the second antenna height change on the absorption rate in the solar absorber of this invention.

[0024] Figure 7 This is a curve showing the effect of the change in the thickness of the ultrathin film layer on the absorption rate in the solar energy absorber of this invention.

[0025] Figure 8 This is a curve showing the effect of the change in the thickness of the dielectric layer in the solar absorber of this invention on the absorption rate.

[0026] Figure 9 This is a color mapping diagram of the absorptivity at different wavelengths in the solar energy absorber of this invention, showing the effect of changes in the solar energy incident angle.

[0027] Figure 10 This is the curve showing the effect of the change in the solar incident angle on the average absorption rate in the solar absorber of this invention.

[0028] Figure 11 This is a color mapping diagram of the effect of solar polarization angle change on absorption rate in the solar energy absorber of this invention.

[0029] The labels in the diagram represent: 1. Substrate layer; 2. Dielectric layer; 3. Ultrathin film layer; 4. Antenna layer; 41. First antenna; 42. Second antenna. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0033] In this invention, unless otherwise explicitly specified and limited, the terms "assembly," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0034] Example 1: like Figure 1 and Figure 2 As shown, the solar energy absorber of this embodiment includes multiple absorber units arranged in a periodic array. Each absorber unit includes a substrate layer 1, a dielectric layer 2, an ultrathin film layer 3, and an antenna layer 4 arranged sequentially from bottom to top. The antenna layer 4 includes a first antenna 41 and four second antennas 42. The projection of the first antenna 41 onto the XOY plane (i.e., the horizontal plane) is a cross shape, and the projection of the second antenna 42 onto the XOY plane is a square. The four second antennas 42 are respectively arranged at the four corners of the first antenna 41. The projections of the substrate layer 1, dielectric layer 2, and ultrathin film layer 3 onto the XOY plane are all squares. The substrate layer 1 is made of TiN material, the dielectric layer 2 is made of Al2O3 material, the ultrathin film layer 3 is made of TiN material, the first antenna 41 is made of Ni material, and the second antenna 42 is made of TiN material.

[0035] Furthermore, in this embodiment, the antenna layer 4 is located directly above the substrate layer 1, the dielectric layer 2, and the ultrathin film layer 3. The origin of the coordinate system is the center of the cross of the first antenna 41, and the two sides of the cross are the X-axis and the Y-axis, respectively. The angle between the line connecting the center of the first antenna 41 and the center of the second antenna 42 and the X-axis and the Y-axis is 45°.

[0036] Furthermore, in this embodiment, the thickness of the substrate layer 1 is 200 nm, the thickness T2 of the dielectric layer 2 is 200 nm, the thickness T1 of the ultrathin film layer 3 is 5 nm, the side lengths of the substrate layer 1, dielectric layer 2, and ultrathin film layer 3 are all 250 nm, the length L1 of the first antenna 41 is 218 nm, the width W1 is 20 nm, and the height H1 is 190 nm, the side length of the second antenna 42 is 50 nm, and the height is 270 nm. The distance between the center of the first antenna 41 and the center of the second antenna 42 is... nm (meaning there is a gap between the second antenna 42 and the first antenna 41), and the array period of the absorber unit is 250 nm.

[0037] Under conditions of 0° incident angle of sunlight (i.e., perpendicular incidence) and a broadband range of 300nm-2500nm, the absorptivity of the solar absorber in this embodiment was tested using FDTD-Solutions software. The absorption effect is as follows: Figure 2 As shown.

[0038] And using the following formula

[0039] Calculate its average absorption rate.

[0040] Where A is the average absorptivity of the absorber, λ is the wavelength of the incident light, and λ max λ 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(λ) is a function of the absorber intensity as a function of the incident light wavelength.

[0041] The average absorption rate of the solar energy absorber in this embodiment is calculated to be 98.1% using the above formula.

[0042] from Figure 2 As can be seen, there are four distinct absorption peaks (a, b, c, d) at 402nm, 540nm, 886nm, and 1939nm, with absorption rates of 99.99%, 99.89%, 98.55%, and 99.38%, respectively. The solar energy absorber in this embodiment has a broadband high absorption spectrum for sunlight.

[0043] The solar absorber of this embodiment has a simple structure with only four stacked layers, and each layer has only square and cross shapes. The Ni cross structure (i.e., the first antenna 41) can be used as an alignment mark for standard electron beam overlay exposure process, which is easy to process and produce. The average absorption rate can reach 98.1% in a wide range of 300nm-2500nm, which can effectively cover the main energy distribution range of the solar spectrum and has the advantages of wide absorption bandwidth and good absorption effect.

[0044] Example 2: like Figure 3 As shown, the processing method of the solar absorber based on Embodiment 1 in this embodiment includes the following steps: Step S1: Deposit the substrate layer 1, dielectric layer 2 and ultrathin film layer 3 sequentially from bottom to top on the support material; Step S2: Spin-coat PMMA electron beam photoresist onto the ultrathin film layer 3; Step S3: Perform electron beam exposure and development of the cross pattern; Step S4: Deposit Ni; Step S5: Remove excess Ni to obtain a Ni cross structure; Step S6: Spin-coat PMMA electron beam photoresist again; Step S7: Deposit TiN; Step S8: Remove excess TiN to obtain a complete solar absorber structure.

[0045] The processing method of the solar absorber in this embodiment can use the Ni cross structure as an alignment mark for standard electron beam overlay exposure process, which is easy to implement in actual production.

[0046] Example 3: This implementation, based on Example 1, simulates and tests the distribution of electric and magnetic fields at different absorption peak wavelengths and locations. For example... Figure 4 As shown, in Figure 4 a- Figure 4 Figure d shows the electric field diagram at y=0nm on the XZ plane for each absorption peak. Figure 4 e- Figure 4 h represents the electric field diagram at y=43nm on the XZ plane for each absorption peak. Figure 4 i- Figure 4 l represents the magnetic field diagram of each absorption peak at y=43nm on the XZ plane of each absorption peak. Localized surface plasmon resonance exists at the interface between the surrounding space and the absorber, while propagating surface plasmon resonance is generated by the propagation of surface plasmon resonance to the surrounding environment. Localized nano-gap surface plasmon resonance mainly appears in the gap between the first antenna 41 and the second antenna 42. Figure 4 a- Figure 4 In d, when λ=402nm, localized surface plasmon resonance appears at the interface between air and the first antenna 41. When λ=540nm, 886nm and 1939nm, it transforms into propagating surface plasmon resonance, which is manifested as an increase in electric field intensity and diffusion to the surrounding environment. Figure 4 e- Figure 4 In h, at λ=886nm, the electric field within the gap between the first antenna 41 and the second antenna 42 is significantly enhanced, and the nanogap plasmon resonance intensity reaches its maximum. However, it does not exhibit the highest absorption rate near the 886nm wavelength, indicating that the absorption performance at this location is not dominated by the nanogap plasmon resonance. Moreover, in Figure 4 a- Figure 4 In d, the electric field enhancement region caused by surface plasmon resonance is the widest when λ=402nm and 540nm, corresponding to the high absorption effect at λ=402nm and 540nm, which illustrates the important role of surface plasmon resonance. Figure 4 i- Figure 4In the first antenna 41, when λ = 402 nm and 540 nm, the magnetic field is mainly confined to the upper surface of the second antenna 42, and its absorption level is dominated by surface plasmon resonance. However, when λ = 886 nm and 1939 nm, the magnetic field is mainly confined to the gap between the first antenna 41 and the second antenna 42, and the vertical surface between the bottom of the second antenna 42 and the air. Its absorption level is jointly determined by surface plasmon resonance and nano-gap plasmon resonance. These characteristic analyses indicate that the high-efficiency absorption performance of the solar energy absorber in this embodiment depends on the combined effect of propagating surface plasmon resonance and localized surface plasmon resonance.

[0047] Example 4: This implementation, based on Example 1, changes the height of the first antenna 41 and performs simulation tests to examine the effect of the height change on the absorption rate. When the height of the first antenna 41 changes from 140nm to 240nm, the absorption rate curve is as follows: Figure 5 As shown in the simulation results, the most significant change is that the absorption peak c disappears when the height of the first antenna 41 is 140 nm and 165 nm. This is because when the height of the first antenna 41 is too low, the coupling effect of the nano-gap plasmonic resonance generated between the first antenna 41 and the second antenna 42, and the nano-gap plasmonic resonance generated between the two second antennas 42, weakens or even disappears, leading to a significant decrease in the absorption rate and the formation of an absorption valley. When the height of the first antenna 41 increases from 190 nm to 240 nm, the absorption peak c first rises from 98.55% to 99.33%, and then decreases to 97.22%, maintaining a high absorption level. When the height of the first antenna 41 increases from 190 nm to 215 nm, the above coupling effect is enhanced, leading to an increase in the absorption rate. When the height of the first antenna 41 increases from 215 nm to 240 nm, the height of 240 nm becomes too close to the height of the second antenna 42 (270 nm), which disrupts the original nanometer gap plasmon resonance between the two second antennas 42, resulting in a slight decrease in absorption rate. The absorption peak d gradually strengthens with the increase of the height H1 of the first antenna 41, accompanied by a redshift. The above analysis demonstrates the rationality of the parameter settings for the solar energy absorber of this invention.

[0048] Example 5: This implementation, based on Example 1, modifies the height of the second antenna 42 and conducts simulation tests to examine the effect of the height change on the absorbance. When the height of the second antenna 42 changes from 220 nm to 320 nm, the absorbance curve is as follows: Figure 6As shown, simulation results indicate that when the height of the second antenna 42 increases from 220 nm to 320 nm, absorption peak a first increases and then decreases, absorption peak b increases from 97.48% to 99.99% with a redshift, and the absorption peak c gradually weakens. When the height H2 of the second antenna 42 is 320 nm, absorption peak c disappears. This is mainly because when the height of the second antenna 42 is too high, the coupling effect of the nano-gap plasmon resonance generated between the second antenna 42 and the first antenna 41, and the nano-gap plasmon resonance generated between the two second antennas 42, may be drastically weakened or even disappear, leading to a significant decrease in absorption rate and the formation of an absorption valley. This is consistent with the case where the height of the first antenna 41 is too low, where absorption peak d is accompanied by a redshift, but still maintains high absorption efficiency. This further proves the rationality of the parameter settings of the solar absorber of the present invention.

[0049] Example 6: This implementation, based on Example 1, modifies the thickness of the ultrathin film layer 3 and simulates the effect of the thickness variation on the absorbance. The absorbance curves are shown below when the thickness of the ultrathin film layer 3 varies from 0 to 15 nm. Figure 7 As shown, simulation results indicate that when the thickness of the ultrathin film layer 3 increases from 0 nm to 15 nm, absorption peaks a and b do not change significantly. Absorption peak c exhibits a noticeable red shift, with its absorptivity increasing from 97.73% to 99.71% with increasing ultrathin film layer 3 thickness. For absorption peak d, when there is no ultrathin film layer 3 (i.e., the thickness of ultrathin film layer 3 is 0), absorption peak d disappears, and the average absorptivity in the near-infrared band decreases significantly. This demonstrates the important role of the ultrathin film layer 3 and also indicates that absorption peak d depends on the FP cavity resonance effect supported by the ultrathin film layer-dielectric layer-metal substrate structure. When the ultrathin film layer 3 increases from 5 nm to 15 nm, absorption peak d undergoes a significant blue shift, leading to an increase in absorptivity in the near-infrared short-wave region and a decrease in absorptivity in the near-infrared long-wave region, but maintaining an overall high absorption level. This further proves the rationality of the solar energy absorber structure design of this invention.

[0050] Example 7: This implementation, based on Example 1, modifies the thickness of dielectric layer 2 and simulates the effect of this thickness change on the absorbance. The absorbance curves are shown below when the thickness of dielectric layer 2 changes from 140 nm to 260 nm. Figure 8As shown, simulation results indicate that absorption peak a gradually splits into two peaks; absorption peak b exhibits a significant redshift, but the absorptivity remains relatively stable; absorption peak c also shows a significant redshift, with its absorption initially decreasing from 99.26% to 98.55% and then increasing to 99.27%; absorption peak d decreases from 99.92% to 98.25% with a redshift. However, the absorption in the region between the two adjacent peaks, absorption peaks c and d, gradually decreases. This is because the enhanced resonance at absorption peaks c and d causes absorption peak c to redshift from 886 nm to 1000 nm, while absorption peak d redshifts from 1939 nm to 2124 nm, increasing the separation between the two absorption peaks and reducing their high absorption width. Overall, a high absorption level is maintained. This further demonstrates the rationality of the solar absorber structure design of this invention.

[0051] Example 8: This implementation, based on Example 1, changes the incident angle of sunlight and simulates the effect of the change in incident angle on the absorption rate at different wavelengths. The color mapping diagram is shown below. Figure 9 As shown, the simulation results indicate that when the incident angle is less than 60°, the absorptivity at both short and long wavelengths does not change significantly. However, when the incident angle is greater than 60°, the absorptivity decreases at both short and long wavelengths. This suggests that the absorber has a good absorption effect within the incident angle range of 0° to 60°, indicating that the solar energy absorber of this invention has excellent wide-angle absorption performance.

[0052] Example 9: This implementation, based on Example 1, modifies the incident angle of sunlight and conducts simulation tests on the effect of the incident angle on the average absorptivity. The absorptivity curve is shown below. Figure 10 As shown in the simulation results, when the incident angle reaches 60°, the average absorptivity can still be maintained above 88%. Even when the incident angle is deflected as high as 76° (in very few application scenarios), the average absorptivity can still reach 62%, absorbing most of the sunlight. This indicates that the solar energy absorber of this invention can support sunlight incident at relatively large angles.

[0053] Example 10: This implementation, based on Example 1, modifies the polarization angle of sunlight and simulates the effect of polarization angle on absorption rate. The color mapping diagram is shown below. Figure 11 As shown in the simulation results, the absorption rate of the absorber does not change significantly when the polarization angle is changed, and the solar energy absorber of the present invention is polarization insensitive as a whole.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A solar energy absorber characterized by: The application relates to a solar energy absorber, which comprises a plurality of absorber units arranged in a periodic array, the absorber unit comprising, from bottom to top, a substrate layer (1), a medium layer (2), an ultrathin film layer (3) and an antenna layer (4), the antenna layer (4) comprising a first antenna (41) and four second antennas (42), the first antenna (41) being in the shape of a cross in the XOY plane, the second antenna (42) being in the shape of a square in the XOY plane, the four second antennas (42) being arranged in the four corners of the first antenna (41) respectively, the substrate layer (1), the medium layer (2) and the ultrathin film layer (3) being all in the shape of a square in the XOY plane, the substrate layer (1) being made of TiN, the medium layer (2) being made of Al2O3, the ultrathin film layer (3) being made of TiN, the first antenna (41) being made of Ni, and the second antenna (42) being made of TiN.

2. The solar energy absorber of claim 1, wherein: The length of the first antenna (41) is 218 nm, the width is 20 nm, and the height is 190 nm.

3. The solar energy absorber of claim 1, wherein: The side length of the second antenna (42) is 50 nm, and the height is 270 nm.

4. The solar energy absorber of claim 1, wherein: The thickness of the substrate layer (1) is 200 nm.

5. The solar energy absorber of claim 1, wherein: The thickness of the medium layer (2) ranges from 140 nm to 260 nm.

6. The solar energy absorber of claim 5, wherein: The thickness of the medium layer (2) is 200 nm.

7. The solar energy absorber of claim 1, wherein: The thickness of the ultrathin film layer (3) is 5 nm.

8. The solar energy absorber of claim 1, wherein: The distance between the center of the first antenna (41) and the center of the second antenna (42) is nm.

9. The solar energy absorber of claim 1, wherein: The array period of the absorber unit is 250 nm.

10. A method of processing a solar absorber according to any one of claims 1 to 9, characterized in that: The application further discloses a preparation method of the solar energy absorber, which comprises the following steps: S1, depositing, from bottom to top, the substrate layer (1), the medium layer (2) and the ultrathin film layer (3) on a supporting material; S2, spin-coating PMMA electron beam resist on the ultrathin film layer (3); S3, performing electron beam exposure and development of a cross-shaped pattern; S4, depositing Ni; S5, stripping the excess Ni to obtain a Ni cross-shaped structure; S6, spin-coating PMMA electron beam resist again; S7, depositing TiN; S8, stripping the excess TiN to obtain a complete solar energy absorber structure.

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