Gold-based metasurface solar photo-thermal converter

Abstract

The invention provides a super-surface solar photo-thermal converter based on gold. The metasurface wave absorber is composed of a plurality of wave absorber units, and each wave absorber unit is composed of a composite structure layer, a silicon dioxide dielectric layer and a metal substrate from top to bottom in sequence, wherein the composite structure layer is composed of gold resonators. Each gold resonator unit is of a composite structure composed of 13 resonant structures of different sizes and shapes, wherein two large cones, a resonator on the left half portion, three split resonant rings on the right half portion and two circular rings are symmetrically distributed about the center point. The material has the characteristics of good thermal stability and wide spectrum absorption, the absorption bandwidth (FWHM) of the material is 297.5 THz in the visible light and near infrared spectral line range (400-750THz) for a solar spectrum, the full spectrum absorption effect is achieved, the broadband wave absorption effect of 90% or above is achieved in the range of 444.4-596THz, the wave absorption bandwidth is 151.6 THz, and the material can be widely applied to the fields of energy, absorbers, seawater desalination and the like.

Description

Technical Field

[0001] The present invention relates to the field of terahertz technology, and in particular to a gold-based super-surface solar thermal converter. Background Art

[0002] Solar photovoltaic power generation and photothermal converters are the two main means of utilizing solar energy. In the field of solar energy utilization, solar converters are crucial to improving the efficiency of solar energy utilization. Traditional solar converters have certain limitations and the utilization rate of solar energy is insufficient. In recent years, metasurface technology has attracted widespread attention due to its unique advantages. In terahertz-related applications, metasurfaces can effectively regulate terahertz waves. For example, the reflection phase of terahertz waves can be controlled by designing metasurface unit structures, thereby affecting performance such as energy conversion efficiency.

[0003] Gold plays an important role in metasurface design due to its excellent physical and chemical properties. Gold metasurfaces exhibit unique optical and electrical properties when interacting with terahertz waves. Solar converters based on gold metasurfaces are expected to solve the problem of insufficient utilization of the solar spectrum range by traditional solar converters, break through the bottleneck of existing technologies, improve the conversion efficiency of solar energy, and meet the growing demand for efficient solar energy conversion in related fields. However, related research is still in the development stage and needs further in-depth exploration.

[0004] In view of the above shortcomings, the present invention designs a solar thermal converter which has the characteristics of good thermal stability and wide spectrum absorption and can be widely used in the fields of energy, absorbers, seawater desalination, etc. Summary of the invention

[0005] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a gold-based metasurface solar thermal converter.

[0006] The technical solution adopted by the present invention is: the absorber unit structure is composed of a composite structure layer composed of gold resonators, a silicon dioxide dielectric layer and a metal substrate from top to bottom. The bottom gold base surface, the middle dielectric layer and the top gold micron resonator are bonded to each other. The bottom gold base surface is a full metal film, and the top gold micron resonator is a composite structure composed of 13 resonators of different sizes and shapes. The large cone, the resonator in the left half, and the three open resonant rings and two circular rings in the right half are symmetrical about the center point.

[0007] The specific technical solution is:

[0008] A gold-based metasurface solar thermal converter, which includes a metal structure layer, an intermediate dielectric layer and a metal bottom plate from top to bottom;

[0009] The metal structure layer is composed of gold nanoresonator array units;

[0010] The middle dielectric layer is silicon dioxide, with a relative dielectric constant of 3.9;

[0011] The metal base plate is made of gold, tungsten, copper or aluminum.

[0012] Furthermore, the metal structure layer is divided into an upper half of the metal structure layer and a lower half of the metal structure layer with the upper and lower symmetric center lines of the metal structure layer as the boundary;

[0013] The gold nanoresonator array contains 13 resonators of different sizes and shapes. The array is divided into left, middle and right halves. Each half includes:

[0014] In the left half, a large open resonant ring, a circular ring-shaped resonator, a small open resonant ring and a medium open resonant ring are arranged in order from top to bottom; there is also a circular ring-shaped resonator on the side of the small open resonant ring close to the middle part; the large open resonant ring and the circular ring-shaped resonator are located in the upper half of the metal structure layer, and the small open resonant ring and the medium open resonant ring are located in the lower half of the metal structure layer;

[0015] In the middle part, there are two large cone-shaped resonators and one small cone-shaped resonator; the small cone-shaped resonator is located in the center of the metal structure layer, and the two large cone-shaped resonators are symmetrically distributed on the upper and lower sides of the small cone-shaped resonator;

[0016] In the right half, there are a medium-sized open resonant ring, a small-sized open resonant ring, a circular-shaped resonator and a large-sized open resonant ring arranged from top to bottom; there is also a circular-shaped resonator on the side of the small-sized open resonant ring close to the middle part; the medium-sized open resonant ring and the small-sized open resonant ring are located in the upper half of the metal structure layer, and the circular-shaped resonator and the large-sized open resonant ring are located in the lower half of the metal structure layer.

[0017] The basic unit structure of the converter is a square, with a periodic side length of 1 micron;

[0018] The thickness of each layer is:

[0019] In the metal structure layer, the thickness of the ring-shaped resonator and the cone-shaped resonator is 0.126 microns, and the thickness of the open resonant ring is 0.226 microns;

[0020] The thickness of the intermediate dielectric layer is 0.06 microns;

[0021] The thickness of the metal substrate is 0.02 microns.

[0022] The sizes and distances of the individual resonators are:

[0023] The radius of the resonator in the shape of a large cone is 0.15 micrometers;

[0024] The resonator radius of the small cone shape is 0.1 micrometer;

[0025] The ring-shaped resonator has an outer radius of 0.06 microns and an inner radius of 0.05 microns;

[0026] The outer side length of the medium-sized open resonant ring is 0.2 microns, and the inner side length is 0.1 microns;

[0027] The outer side length of the small open resonant ring is 0.18 microns, and the inner side length is 0.09 microns;

[0028] The outer side length of the large open resonant ring is 0.22 microns, and the inner side length is 0.11 microns;

[0029] The distance between the medium-sized open resonant ring, the large-sized open resonant ring, and the large cone-shaped resonator and the edge of the metal structure layer is 0.05 microns;

[0030] The distance between the small open resonant ring and the edge of the metal structure layer is 0.06 microns;

[0031] The distance between the ring-shaped resonator between the large open resonant ring and the small open resonant ring and the edge of the metal structure layer is 0.09 microns;

[0032] The ring-shaped resonator on one side of the small open resonant ring is 0.02 microns away from the small open resonant ring;

[0033] The tangent points of all the circular-shaped resonators closest to the vertical symmetric center line of the metal structure layer have a vertical distance of 0.02 microns from the vertical symmetric center line of the metal structure layer;

[0034] The distance between the large cone-shaped resonator and the small cone-shaped resonator is 0.05 micrometers;

[0035] The distance between the medium-sized split resonant ring and the small-sized split resonant ring is 0.06 microns;

[0036] The vertical distance between the small open resonant ring and the center point is 0.01 micron;

[0037] The opening lengths of the medium-sized open resonant ring, the small-sized open resonant ring and the large-sized open resonant ring are all the same, which is 0.1 microns.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The top layer of the solar thermal converter uses a composite structure composed of 13 resonators of different sizes and shapes. It is compact, symmetrically distributed, easy to implement, and polarization-insensitive.

[0040] (2) The solar thermal converter proposed in the present invention has a bandwidth of 297.5 THz, calculated based on the full width at half maximum, covering the visible light and near-infrared bands, achieving a full-spectrum absorption effect, and realizing a broadband absorption effect of more than 90% in the range of 444.4-596 THz, with an absorption bandwidth of 151.6 THz. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of the top structural pattern of the basic unit structure of the converter of the present invention;

[0042] Figure 2 A side view of the basic unit structure of the converter of the present invention;

[0043] Figure 3 The converter of the present invention has only a single structure of a circular ring and a wave absorption rate curve;

[0044] Figure 4 The converter of the present invention has only a single cone structure absorption rate curve;

[0045] Figure 5 The wave absorption rate curve of the converter of the present invention having only a single structure of an open resonant ring;

[0046] Figure 6 The wave absorption rate curve of the composite structure of the converter of the present invention at a simulation frequency of 430-750THz;

[0047] Figure 7 The wave absorption rate curve of the composite structure of the converter of the present invention at a simulation frequency of 400-750THz.

[0048] Figure 8 The wave absorption rate curve diagram when different metal materials (copper, gold, aluminum, and tungsten have electrical conductivities of 5.96, 4.52, 3.77, and 1.89*107S / m, respectively) are replaced for the converter of the present invention;

[0049] Fig. 9 This is the current distribution on the surface of the converter of the present invention. DETAILED DESCRIPTION

[0050] The present invention is further described below in conjunction with the accompanying drawings.

[0051] like Figure 1 He Ru Figure 2 As shown, a gold-based metasurface solar thermal converter includes a metal structure layer, an intermediate dielectric layer and a metal bottom plate from top to bottom;

[0052] The metal structure layer is composed of gold nanoresonator array units;

[0053] The middle dielectric layer is silicon dioxide, with a relative dielectric constant of 3.9;

[0054] The metal base plate is made of gold, tungsten, copper or aluminum.

[0055] The metal structure layer is divided into an upper half of the metal structure layer and a lower half of the metal structure layer by taking the upper and lower symmetric center lines of the metal structure layer as the boundary;

[0056] The gold nanoresonator array contains 13 resonators of different sizes and shapes. The array is divided into left, middle and right halves. Each half includes:

[0057] In the left half, a large open resonant ring, a circular ring-shaped resonator, a small open resonant ring and a medium open resonant ring are arranged in order from top to bottom; there is also a circular ring-shaped resonator on the side of the small open resonant ring close to the middle part; the large open resonant ring and the circular ring-shaped resonator are located in the upper half of the metal structure layer, and the small open resonant ring and the medium open resonant ring are located in the lower half of the metal structure layer;

[0058] In the middle part, there are two large cone-shaped resonators and one small cone-shaped resonator; the small cone-shaped resonator is located in the center of the metal structure layer, and the two large cone-shaped resonators are symmetrically distributed on the upper and lower sides of the small cone-shaped resonator;

[0059] In the right half, a medium-sized open resonant ring, a small-sized open resonant ring, a circular-shaped resonator and a large-sized open resonant ring are arranged in sequence from top to bottom; there is also a circular-shaped resonator on the side of the small-sized open resonant ring close to the middle part; the medium-sized open resonant ring and the small-sized open resonant ring are located in the upper half of the metal structure layer, and the circular-shaped resonator and the large-sized open resonant ring are located in the lower half of the metal structure layer;

[0060] The basic unit structure of the converter is a square, and the period side length P is 1 micron;

[0061] The thickness of each layer is:

[0062] In the metal structure layer, the thickness h3 of the annular resonator and the conical resonator is 0.126 micrometers, and the thickness h4 of the open resonant ring is 0.226 micrometers.

[0063] The thickness of the intermediate dielectric layer h2 is 0.06 microns;

[0064] The thickness h1 of the metal base plate is 0.02 micrometers.

[0065] The sizes and distances of the individual resonators are:

[0066] The radius r1 of the resonator with a large cone shape is 0.15 microns;

[0067] The radius r2 of the resonator in the small cone shape is 0.1 micrometer;

[0068] The outer radius r4 of the ring-shaped resonator is 0.06 microns, and the inner radius r3 is 0.05 microns;

[0069] The outer side length w1 of the medium-sized open resonant ring is 0.2 microns, and the inner side length w'1 is 0.1 microns;

[0070] The outer side length w2 of the small open resonant ring is 0.18 microns, and the inner side length w'2 is 0.09 microns;

[0071] The outer side length w3 of the large open resonant ring is 0.22 microns, and the inner side length w'3 is 0.11 microns.

[0072] The distance between the edge of the medium-sized open resonant ring, the large-sized open resonant ring, and the large cone-shaped resonator and the metal structure layer is l1, which is 0.05 microns;

[0073] The distance l4 between the edge of the small open resonant ring and the metal structure layer is 0.06 microns;

[0074] The distance l5 between the ring-shaped resonator between the large open resonant ring and the small open resonant ring and the edge of the metal structure layer is 0.09 micrometers;

[0075] The ring-shaped resonator on one side of the small open resonant ring has a distance l2 of 0.02 microns from the small open resonant ring;

[0076] The tangent point of all the circular resonators closest to the vertical symmetric center line of the metal structure layer has a vertical distance l2 of 0.02 microns to the vertical symmetric center line of the metal structure layer;

[0077] The distance l1 between the large cone-shaped resonator and the small cone-shaped resonator is 0.05 micrometers;

[0078] The distance l4 between the medium-sized split resonant ring and the small-sized split resonant ring is 0.06 microns;

[0079] The vertical distance l3 between the small open resonant ring and the center point is 0.01 microns.

[0080] The opening lengths of the medium-sized open resonant ring, the small-sized open resonant ring and the large-sized open resonant ring are all the same, and the opening length l1 is 0.1 microns.

[0081] The preparation process of a gold-based supersurface solar thermal converter provided by the present invention is as follows:

[0082] 1) Design of metasurface absorber unit;

[0083] 2) Design a composite structure with thirteen resonators of different sizes and shapes on the top layer. The material of the entire composite structure is gold with a conductivity of 4*107 Siemens. Figure 1 shown.

[0084] 3) Design the intermediate dielectric layer: Use silicon dioxide material with a dielectric constant of 3.8 to create a dielectric layer with a unit period of P = 1 micron and a thickness of h2 = 0.06 micron, such as Figure 2 shown.

[0085] 4) Design the metal base plate: Use a gold film material with a conductivity of 4*107 Siemens to create a gold base surface with a unit period of P = 1 micron and a thickness of h1 = 0.02 micron, such as Figure 2 shown.

[0086] 5) Set the simulation frequency range: 430–750 THz.

[0087] 6) The electromagnetic simulation software CST Microwave Studio was used to construct the absorber model. The magnetic (Ht=0) boundary conditions were used in the x-direction and the electric (Et=0) boundary conditions were used in the y-direction. The open add space boundary condition was used in the z-direction. The Floquet port was used for excitation. The incident electromagnetic wave was a plane electromagnetic wave, which was incident vertically along the -z direction.

[0088] When the conductivity of gold is 4.561*10^7S / m (metallic state), the absorption rate curve of the metasurface solar thermal converter of the present invention is as follows: Figure 4 As shown. The expected value of the absorber's absorption rate is set to 97%, and the relative error of the absorption rate is 3%. After simulation, the average absorption rate in the range of 444.4-596THz is 97.6%, the absorption bandwidth is 151.6THz, and the relative error is less than the maximum allowable error of 3%, which shows that the absorber proposed in the present invention can achieve a nearly perfect absorption effect.

[0089] Figure 3 , Figure 4 and Figure 5 These are the absorption curves of the single structures of the ring, cone, and open resonant ring. Figure 7 , Figure 8 It is divided into the absorption rate curve of the composite structure with simulation frequency of 400-750THz and 430-750THz. It can be seen from the figure that the absorber based on each individual structure has low absorption rate and narrow absorption bandwidth. When the three individual structures are combined together, the structure can achieve wide-band perfect absorption through the coupling effect between the structures.

[0090] Figure 8The absorption curves are shown when different metal materials are replaced (copper, gold, aluminum, and tungsten have conductivity of 5.96, 4.52, 3.77, and 1.89*107S / m, respectively). As the conductivity changes due to the replacement of metals, it can be seen that Au has the best absorption curve in the 400-750THz frequency band, and various metals have similar broadband absorption characteristics, which indicates that the metal absorber of the present invention has potential application prospects in the fields of absorbers, heat storage devices, and photodetectors.

[0091] Fig. 9 The surface current distribution of the gold metasurface solar thermal converter, the annular metal patch and the conical patch, at the frequency point of 502.9THz, the current and the open resonant ring achieve resonant coupling, and the resonant ring and the circular ring are coupled, thereby generating a circular current distribution at the conical surface to achieve energy localization. It tends to flow along the boundary of the structure, thus forming a circular distribution, which is conducive to the storage and transmission of electromagnetic energy. The six open resonant rings themselves have an annular structure. This geometric shape makes it easier for the current to form a circular flow on the ring. Under the excitation of the 502.9THz wave, electrons will flow along the path of the ring, thereby generating a circularly distributed surface current. Moreover, the change in charge distribution at the opening will affect the current path, causing the current to be redistributed on the ring to achieve balance, further strengthening the characteristics of the circular current. When the frequency reaches 502.9 THz, the frequency is close to the resonant frequency of the open resonant ring, which will induce electromagnetic resonance. In the resonant state, the electromagnetic field energy is continuously stored and released in the open resonant ring, providing a continuous driving force for the surface current, prompting the current to flow along the direction of the ring, forming a stable and obvious annular current distribution, so as to achieve effective coupling between the electromagnetic energy and the resonant ring.

Claims

1. A gold-based metasurface solar thermal converter, characterized in that: From top to bottom, it includes a metal structure layer, an intermediate dielectric layer and a metal bottom plate; The metal structure layer is composed of gold nanoresonator array units; The middle dielectric layer is silicon dioxide, with a relative dielectric constant of 3.9; The metal base plate is made of gold, tungsten, copper or aluminum.

2. A gold-based metasurface solar thermal converter according to claim 1, characterized in that: The metal structure layer is divided into an upper half of the metal structure layer and a lower half of the metal structure layer by taking the upper and lower symmetric center lines of the metal structure layer as the boundary; The gold nanoresonator array contains 13 resonators of different sizes and shapes. The array is divided into the left half, the middle half, and the right half. Each half includes: In the left half, a large open resonant ring, a circular resonator, a small open resonant ring and a medium open resonant ring are arranged from top to bottom; there is also a circular resonator on the side of the small open resonant ring close to the middle part; the large open resonant ring and the circular resonator are located in the upper half of the metal structure layer, and the small open resonant ring and the medium open resonant ring are located in the lower half of the metal structure layer; In the middle part, there are two large cone-shaped resonators and one small cone-shaped resonator; the small cone-shaped resonator is located in the center of the metal structure layer, and the two large cone-shaped resonators are symmetrically distributed on the upper and lower sides of the small cone-shaped resonator; In the right half, there are a medium-sized open resonant ring, a small-sized open resonant ring, a circular-shaped resonator and a large-sized open resonant ring arranged from top to bottom; there is also a circular-shaped resonator on the side of the small-sized open resonant ring close to the middle part; the medium-sized open resonant ring and the small-sized open resonant ring are located in the upper half of the metal structure layer, and the circular-shaped resonator and the large-sized open resonant ring are located in the lower half of the metal structure layer.

3. A gold-based metasurface solar thermal converter according to claim 2, characterized in that: The basic unit structure of the converter is a square, with a periodic side length of 1 micron; The thickness of each layer is: In the metal structure layer, the thickness of the ring-shaped resonator and the cone-shaped resonator is 0.126 microns, and the thickness of the open resonant ring is 0.226 microns; The thickness of the intermediate dielectric layer is 0.06 microns; The thickness of the metal substrate is 0.02 microns.

4. A gold-based metasurface solar thermal converter according to claim 2, characterized in that: The sizes and distances of the individual resonators are: The radius of the resonator in the shape of a large cone is 0.15 micrometers; The resonator radius of the small cone shape is 0.1 micrometer; The ring-shaped resonator has an outer radius of 0.06 microns and an inner radius of 0.05 microns; The outer side length of the medium-sized open resonant ring is 0.2 microns, and the inner side length is 0.1 microns; The outer side length of the small open resonant ring is 0.18 microns, and the inner side length is 0.09 microns; The outer side length of the large open resonant ring is 0.22 microns, and the inner side length is 0.11 microns; The distance between the medium-sized open resonant ring, the large-sized open resonant ring, and the large cone-shaped resonator and the edge of the metal structure layer is 0.05 microns; The distance between the small open resonant ring and the edge of the metal structure layer is 0.06 microns; The distance between the ring-shaped resonator between the large open resonant ring and the small open resonant ring and the edge of the metal structure layer is 0.09 microns; The ring-shaped resonator on one side of the small open resonant ring is 0.02 microns away from the small open resonant ring; The tangent points of all the circular-shaped resonators closest to the vertical symmetric center line of the metal structure layer have a vertical distance of 0.02 microns from the vertical symmetric center line of the metal structure layer; The distance between the large cone-shaped resonator and the small cone-shaped resonator is 0.05 micrometers; The distance between the medium-sized split resonant ring and the small-sized split resonant ring is 0.06 microns; The vertical distance between the small open resonant ring and the center point is 0.01 micron; The opening lengths of the medium-sized open resonant ring, the small-sized open resonant ring and the large-sized open resonant ring are all the same, which is 0.1 microns.

5. The gold-based metasurface solar thermal converter according to claim 2, characterized in that: The material of the metal structure layer is any one of gold, silver, copper, aluminum and tungsten.

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