Radiation heat flow regulating device and application thereof

Abstract

The application belongs to the technical field of thermal radiation, and particularly relates to a radiation heat flow regulating device and application thereof. The radiation heat flow regulating device comprises at least two oppositely arranged radiation bodies, each of which comprises a radiation layer; at least one of the radiation bodies comprises a substrate and one or more organic polymer layers, wherein the organic polymer layer is arranged between the substrate and the radiation layer to reduce the radiation absorption of materials other than the radiation layer. The radiation spectrum mismatch between the organic polymer layer and the radiation layer can effectively reduce the heat energy absorbed by the substrate or other materials to establish an efficient heat radiation channel, which is beneficial to improving the thermal rectification ratio of the thermal rectifier and improving the output power and energy conversion efficiency of the thermal photovoltaic device. The radiation heat flow regulating device is prepared into a heat flow regulating device, such as a thermal diode, a thermal triode, a thermal photovoltaic device, a thermal switch, a thermal imager, a thermal lithography instrument and the like, which can effectively regulate the heat flow.

Description

Technical Field

[0001] This application belongs to the field of thermal radiation technology, specifically relating to a radiation heat flow control device and its application. Background Technology

[0002] Heat transfer is one of the most fundamental physical phenomena in nature, widely present in scientific research, production, and daily life. Over 90% of global energy production is related to heat; therefore, effective regulation of heat transfer processes is crucial for developing novel thermal devices, advancing advanced thermal management technologies, and improving energy efficiency. People's daily lives are inextricably linked to heat, from clothing and cooking to indoor temperature control and vehicle air conditioning, encompassing all aspects of clothing, food, housing, and transportation. The continuous development of heat transfer regulation technologies holds the promise of further improving people's living standards.

[0003] Nonlinear thermal devices derived from heat transfer are key to achieving effective heat management and efficient utilization. For example, nonlinear electrical devices such as diodes and transistors are the cornerstone of modern electronic information infrastructure. Based on the different heat transport carriers, heat flow control devices can be divided into three types: those utilizing phonons, electrons, and photons. Radiation heat flow control devices are a type of nonlinear thermal device based on photon-based heat transport.

[0004] Thermal radiation is essentially an electromagnetic wave generated by the random thermal motion of electrical charges within an object. It includes propagating waves and evanescent waves, with the amplitude of evanescent waves decreasing exponentially with distance from the object's surface. Therefore, when the distance between radiators is greater than the thermal characteristic wavelength, heat can only be transported through propagating waves; this is called far-field thermal radiation, and its radiation law is described by the blackbody radiation law. However, when the distance between radiators is close to or less than the thermal characteristic wavelength, evanescent waves gradually participate in and even dominate radiative heat transfer, breaking the classical laws of thermal radiation; this phenomenon is called near-field thermal radiation.

[0005] Heat flow control devices based on near-field thermal radiation typically have two ends, namely two radiators, and the heat flow is transmitted between the two radiators in the form of electromagnetic waves. Because near-field thermal radiation-based heat flow control devices can utilize various electromagnetic modes to modulate the heat flow, they are expected to achieve better heat flow control performance, such as effectively improving the thermal rectification ratio. They have attracted widespread attention in various nonlinear thermal devices such as thermal diodes, thermal transistors, thermal switches, and thermal photovoltaics.

[0006] However, existing heat flow control devices based on near-field thermal radiation still have performance issues, such as:

[0007] (1) The thermal rectification ratio of thermal rectifiers based on thermal rectification effect is relatively low.

[0008] (2) The output power and energy conversion efficiency of thermophotovoltaic devices are not high. Summary of the Invention

[0009] The technical objective of this application is to at least solve the problem of unsatisfactory performance of existing heat flow control devices based on near-field thermal radiation.

[0010] The first aspect of this application discloses a radiative heat flow control device comprising at least two radiators disposed opposite to each other, each of the radiators comprising a radiating layer;

[0011] At least one radiator comprises a substrate and one or more organic polymer layers, the organic polymer layers being located between the substrate and the radiating layer to reduce radiation absorption by materials other than the radiating layer.

[0012] The radiation spectrum mismatch between the organic polymer layer and the radiation layer in this application can effectively reduce the heat energy absorbed by the substrate or other materials to create an efficient thermal radiation channel, which is beneficial to improving the thermal rectification ratio of thermal rectifier devices and improving the output power and energy conversion efficiency of thermal photovoltaic devices.

[0013] In some embodiments of this application, the organic polymer layer either does not support surface polaritogenic properties or supports weak surface polaritogenic properties; the organic polymer layer satisfies one or more of the following combinations:

[0014] (1.1) The organic polymer layer contains a molecular weight of 10 4 ~10 6 One or a combination of two of the following: carbon polymers or SU-8 photoresist;

[0015] (1.2) The thickness of the organic polymer layer is not less than the thickness of the radiation layer;

[0016] (1.3) The thickness of the organic polymer layer is not greater than the thickness of the substrate.

[0017] In some embodiments of this application, the organic polymer layer comprises one or more of polydimethylsiloxane, poly(p-xylenedicarboxylate), polyimide, polyethylene, polymethyl methacrylate, and SU-8 negative photoresist.

[0018] In some embodiments of this application, the thickness of the organic polymer layer is less than 10 μm.

[0019] In some embodiments of this application, the radiator further includes an intermediate layer, which is also located between the substrate and the radiating layer;

[0020] The organic polymer layer is configured in any of the following ways:

[0021] (2.1) The organic polymer layer is located between the intermediate layer and the radiation layer;

[0022] (2.2) The organic polymer layer is located between the intermediate layer and the base layer.

[0023] In some embodiments of this application, the radiating layer, the substrate, and the intermediate layer satisfy one or two of the following:

[0024] (3.1) At least one of the radiation layer, the substrate, and the intermediate layer has the property of supporting surface polaritons;

[0025] (3.2) One or more of the radiating layer, substrate, and intermediate layer contain any one of polar dielectric, metal, and semiconductor;

[0026] The polar dielectric comprises one or more of cubic boron nitride, hexagonal boron nitride, lithium hydride, lithium fluoride, cesium fluoride, boron nitride, silicon carbide, silicon dioxide, silver chloride, magnesium oxide, barium fluoride, indium antimonide, gallium arsenide, and indium gallium arsenide.

[0027] The metal comprises one or more of the following: gold, silver, aluminum, copper, chromium, zinc, iron, and nickel.

[0028] The semiconductor comprises one or more of indium arsenide, doped silicon, high-resistivity silicon, intrinsic silicon, gallium, selenium, indium, tin, and tellurium.

[0029] In some embodiments of this application, a vacuum gap is provided between the two oppositely arranged radiators, and the vacuum gap is not greater than the thermal characteristic wavelength of the device at low temperature.

[0030] In some embodiments of this application, the vacuum spacing is 10 nm to 10 μm.

[0031] In some embodiments of this application, the substrate includes a groove structure formed after etching.

[0032] A second aspect of this application is to provide a heat flow regulating device, the heat flow regulating device comprising the device described in the first aspect;

[0033] The heat flow regulating device includes any one of the following: thermal diode, thermal triode, thermal photovoltaic, thermal switch, thermal imager, and thermal lithography.

[0034] The heat flow regulating device provided in this application is beneficial for achieving effective control of heat flow. Attached Figure Description

[0035] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0036] Figure 1 A schematic diagram illustrating the principle of a thermal diode based on thermal radiation is shown.

[0037] Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 A schematic diagram of the structure of a radiative heat flux control device according to an embodiment of this application is shown.

[0038] Figure 8 A schematic flowchart of the design of a radiative heat flux control device according to an embodiment of this application is shown.

[0039] Figure 9 , Figure 10 , Figure 11 , Figure 12 A schematic diagram of the structure of a thermal diode according to an embodiment of this application is shown.

[0040] Figure 13 schematically shown Figures 9 to 12 The local electromagnetic density of states characteristic test image of the thermal diode at 100 nm on the lithium hydride side surface;

[0041] Figure 14 schematically shown Figures 9 to 12 A schematic diagram showing the relationship between the forward and reverse radiative heat flow of a thermal diode and the vacuum gap;

[0042] Figure 15 schematically shown Figures 9 to 12 A schematic diagram showing the relationship between the thermal rectification ratio of a thermal diode and the vacuum gap;

[0043] Figure 16 schematically shown Figures 9 to 12 A schematic diagram showing the relationship between the thermal rectification ratio boost factor of a thermal diode and the vacuum gap;

[0044] Figure 17 , Figure 18 A schematic diagram of a thermophotovoltaic system according to an embodiment of this application is shown.

[0045] Figure 19 schematically shown Figures 17 to 18The radiation spectrum of thermophotovoltaics at a vacuum spacing of 10 nm;

[0046] Figure 20 schematically shown Figures 17 to 18 A schematic diagram showing the relationship between the total radiative heat flux, power output density, and hexagonal boron nitride thickness in a thermophotovoltaic system.

[0047] The component numbers in the attached diagram are as follows:

[0048] 2000, Device; 1000, Radiator; 100, Radiating Layer; 200, Substrate; 300, Organic Polymer Layer; 400, Intermediate Layer. Detailed Implementation

[0049] The physical mechanisms underlying different nonlinear thermal devices such as thermal diodes, thermal transistors, thermal switches, and thermal photovoltaics are quite similar. In near-field thermal radiation, they can be summarized as follows: by using different triggering mechanisms such as heat, light, and electricity, different electromagnetic waves in near-field thermal radiation are modulated, thereby changing the magnitude of radiative heat flux.

[0050] Among them, thermal diodes based on the thermal rectification effect are a very typical method of heat flow control. Under the same temperature difference, the magnitude of heat flow in a thermal rectification device is related to the temperature bias direction. When the temperature bias direction changes, the change in dielectric constant will lead to a difference in radiative heat flow, thus forming thermal rectification. The core performance parameter of thermal rectification is the rectification ratio, which is defined as the ratio of the difference between the forward and reverse heat flow to the smaller reverse heat flow. The larger the rectification ratio, the better the thermal radiation performance of the device. Theoretically, the rectification ratio of near-field radiative thermal diodes can reach 10. 9 However, the maximum rectification ratio that can be achieved in experiments is only between 1 and 100.

[0051] Thermophotovoltaics is an energy conversion technology that directly converts radiant heat energy into electrical energy through the photoelectric effect of the pn junction of a semiconductor photovoltaic cell. It can utilize photons with energy levels smaller than the bandgap, which are unusable by ordinary photovoltaic devices. Theoretically, the energy conversion efficiency of near-field thermophotovoltaics can exceed 50%, but experimentally, less than 10% can be achieved.

[0052] The reasons for the unsatisfactory rectification ratio of the above-mentioned thermal rectifier devices based on the thermal rectification effect and the relatively low output power and energy conversion efficiency of the thermophotovoltaic devices can be found that, in addition to the unavoidable performance degradation caused by the quality problems of the prepared materials themselves, the energy loss of the radiant material during the radiative heat transfer process is the main influencing factor.

[0053] In nonlinear thermal devices that utilize near-field thermal radiation, the radiator material is often relatively thin (less than 10 μm thick), and it needs to be placed on a substrate or other supporting material, which leads to unnecessary thermal radiation absorption.

[0054] To improve the near-field thermal radiation performance of nonlinear thermal devices by enhancing the heat radiation transfer pathway, materials with low dielectric constants and dielectric losses can be used as interlayer dielectrics and substrates to reduce unnecessary thermal radiation absorption. Currently widely used materials with low dielectric constants and dielectric losses include highly transparent dielectric materials such as silicon dioxide, magnesium fluoride, barium fluoride, sodium chloride, and potassium chloride. These materials generate supporting interface phonon polaritons (SPhPs) in the infrared band, which increase the total heat flux of the thermal flux control device through coupling with the radiator material. However, this portion of heat not transferred by the radiator material limits the performance of the thermal flux control device.

[0055] To address the aforementioned technical problems, this application provides a radiative heat flux control device. The device comprises at least two opposing radiators, each radiator including a radiating layer. At least one radiator includes a substrate and one or more organic polymer layers, wherein the organic polymer layer is located between the substrate and the radiating layer to reduce radiation absorption by materials other than the radiating layer. This spectral mismatch between the organic polymer layer and the radiating layer effectively reduces the heat energy absorbed by the substrate or other materials, creating a highly efficient thermal radiation channel. This is beneficial for improving the thermal rectification ratio of thermal rectifiers and enhancing the output power and energy conversion efficiency of thermophotovoltaic devices.

[0056] The radiative heat flux control device provided in this application has good applications in heat flux regulation. For example, the radiative heat flux control device can be fabricated into a heat flux regulation device, such as a thermal diode, thermal transistor, thermal photovoltaic, thermal switch, thermal imager, thermal lithography instrument, etc., to achieve effective regulation of heat flux.

[0057] In some embodiments of this application, such as Figures 2 to 7 The present application discloses a radiative heat flow control device, which includes at least two radiators 1000 disposed opposite to each other, each radiator 1000 including a radiating layer 100, and at least one radiator 1000 including a substrate 200 and one or more organic polymer layers 300, the organic polymer layers 300 being located between the substrate 200 and the radiating layer 100 to reduce the radiation absorption of materials other than the radiating layer.

[0058] The radiative heat flow control device in this application may include two or more radiators 1000. For example, it may include two radiators 1000 to form a thermal diode, or three radiators to form a thermal triode, etc. In specific embodiments, this application mainly focuses on discussing thermal diodes formed by two radiators 1000.

[0059] The radiating layer 100 in this application includes a primary radiating material, which is mainly used to achieve radiative heat transfer. This radiative heat transfer is easily absorbed by the substrate or other materials besides the primary radiating material, thus affecting the performance of the radiative heat flow control device. This application chooses to place one or more organic polymer layers 300 as spacers between the substrate 200 and the radiating layer 100 to achieve a spectral mismatch between the organic polymer layer and / or other intermediate material layers and the radiating layer. This effectively reduces the heat energy absorbed by the substrate or other materials to create a highly efficient thermal radiation channel, thereby achieving the technical objective of improving the thermal rectification ratio of the thermal rectifier device and improving the output power and energy conversion efficiency of the thermophotovoltaic device.

[0060] To achieve the functions of the aforementioned organic polymer layer, in some embodiments of this application, the organic polymer layer either does not support surface polariton characteristics or supports weak surface polariton characteristics, thereby facilitating the achievement of the technical objective of radiation spectrum mismatch between the organic polymer layer and the radiation layer. Simultaneously, the organic polymer layer satisfies one or more of the following combinations:

[0061] (1.1) The organic polymer layer contains a molecular weight of 10 4 ~10 6 One or a combination of two of the following: carbon polymers or SU-8 photoresist;

[0062] (1.2) The thickness of the organic polymer layer shall not be less than the thickness of the radiation layer;

[0063] (1.3) The thickness of the organic polymer layer is not greater than the thickness of the substrate.

[0064] The organic polymer layer in this application contains a molecular weight of 10. 4 ~10 6 One or both of the following: carbonaceous polymers or SU-8 photoresists, wherein the carbonaceous polymer contains nonpolar functional groups, such as hydrocarbon groups, and the carbonaceous polymer or SU-8 photoresist has low dielectric constant, low dielectric loss, low reflectance, low absorption and high transmittance in the far-infrared to near-ultraviolet range. It does not support surface polariton characteristics or supports weak surface polaritons, so as to cause radiation spectrum mismatch between the organic polymer layer and the radiation layer, thereby reducing the heat energy absorbed by the substrate or other materials to create an efficient thermal radiation channel.

[0065] The thickness of the organic polymer layer in this application affects its function. This application selects an organic polymer layer thickness that is not less than the thickness of the radiation layer and / or an organic polymer layer thickness that is not greater than the thickness of the substrate to optimize its function.

[0066] In some embodiments of this application, the thickness of the organic polymer layer is less than 10 μm, such as 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, etc.

[0067] In some embodiments of this application, the thickness of the radiation layer is less than 10 μm, such as 9 μm, 8 μm, 7 μm, 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, 1 μm, 0.5 μm, etc.

[0068] In some embodiments of this application, the thickness of the radiation layer is less than 1 μm.

[0069] In some embodiments of this application, the thickness of the radiating layer is less than 100 nm.

[0070] In some embodiments of this application, the organic polymer layer comprises one or more of polydimethylsiloxane (PDMS), poly(p-xylenedicarboxylate) (PARYLENE), polyimide (PI), polyethylene (PE), polymethyl methacrylate (PMMA), and SU-8 negative photoresist.

[0071] This application selects an organic polymer layer with the aforementioned material, which not only achieves its functional purpose but is also easily fabricated on a substrate or radiating layer. For example, this application can choose to directly coat the organic polymer coating onto the surface of the substrate or radiating layer, or it can involve first preparing the organic polymer layer and then using methods such as transfer or heating to composite the organic polymer layer with the substrate or radiating layer. The organic polymer layer material selected in this application is compatible with the fabrication processes of radiative heat flux control devices, such as micro-nano fabrication processes, thus enabling process implementation and improving device fabrication yield. Furthermore, during micro-nano fabrication, heating can be used to enhance the contact between the organic polymer layer and the substrate or other intermediate layer materials, achieving near-ideal interfacial radiation characteristics.

[0072] In some embodiments of this application, such as Figure 4 , Figure 5 As shown, the radiator also includes an intermediate layer 400, which is also located between the substrate 200 and the radiating layer 100.

[0073] The organic polymer layer 300 is configured in any of the following ways:

[0074] (2.1) The organic polymer layer 300 is located between the intermediate layer 400 and the radiation layer 100;

[0075] (2.2) The organic polymer layer 300 is located between the intermediate layer 400 and the substrate 200.

[0076] In this application, whether the organic polymer layer is located between the intermediate layer and the radiation layer or between the intermediate layer and the substrate, it does not affect its technical effect as a spacer layer to achieve the radiation spectrum mismatch with the radiation layer. At the same time, the addition of the intermediate layer is beneficial to further improve the radiation spectrum mismatch between the organic polymer layer and the radiation layer.

[0077] In some embodiments of this application, the radiating layer, the substrate, and the intermediate layer satisfy one or two of the following:

[0078] (3.1) At least one of the radiating layer, the substrate, and the intermediate layer has the property of supporting surface polaritons;

[0079] (3.2) One or more of the radiating layer, substrate, and intermediate layer contain any one of polar dielectric, metal, and semiconductor;

[0080] At least one of the radiating layer, substrate, and intermediate layer in this application possesses surface polariton characteristics, and the dielectric response of the corresponding material changes drastically with temperature. By utilizing the evanescent modes on the surface of this material and the differences in the local electromagnetic state density of the surface at different temperatures, the radiative heat flow modulation device can greatly enhance the radiative heat flow between the main radiating materials under a certain temperature gradient and suppress the radiative heat flow under the opposite temperature gradient.

[0081] The polar dielectric, metal, or semiconductor in this application satisfies the surface polariton characteristic.

[0082] In some embodiments of this application, the polar dielectric comprises a material that supports surface phonon polaritons, such as one or more combinations of cubic boron nitride, hexagonal boron nitride, lithium hydride, lithium fluoride, cesium fluoride, boron nitride, silicon carbide, silicon dioxide, silver chloride, magnesium oxide, barium fluoride, indium antimonide, gallium arsenide, and indium gallium arsenide.

[0083] In some embodiments of this application, the metal comprises a material that supports surface plasmon polaritons, such as one or two of gold, silver, aluminum, copper, chromium, zinc, iron, and nickel.

[0084] In some embodiments of this application, the semiconductor comprises one or more combinations of indium arsenide, doped silicon, high-resistivity silicon, intrinsic silicon, gallium, selenium, indium, tin, and tellurium.

[0085] In some embodiments of this application, the substrate may not be etched; at the same time, the substrate may be etched to form a groove structure, for example... Figure 6 , Figure 7 As shown.

[0086] Combination Figures 2 to 7It is known that there is a vacuum gap between the two radiators arranged opposite each other, and this vacuum gap is not greater than the thermal characteristic wavelength of the device at low temperature.

[0087] In some embodiments of this application, the vacuum spacing is 10nm~10μm. For example, 10nm, 50nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1000nm, 2μm, 4μm, 6μm, 8μm, 10μm, etc.

[0088] In some embodiments of this application, the radiation layer may have a grating and / or metasurface structure, and may also include other structures conventional in the art.

[0089] In some embodiments of this application, the structure of the radiative heat flux control device includes either a plate-plate or a plate-sphere structure; wherein, for the plate-sphere structure, the radiator containing the organic polymer spacer layer is a planar structure. Furthermore, the thicknesses of the radiators disposed opposite to each other can be equal or unequal.

[0090] In some embodiments of this application, a design method for a radiative heat flux control device is disclosed, such as... Figure 8 The design method described herein includes:

[0091] S1. Select and determine the target radiative heat flux control device and its corresponding radiative layer material and device size;

[0092] S2. Select and determine the substrate material; if the device contains other intermediate layers, the intermediate layer material also needs to be selected and determined.

[0093] S3. Select and determine the material for the organic polymer layer;

[0094] S4. Investigate parameters such as the thickness of the organic polymer layer to optimize device performance.

[0095] The organic polymer materials selected in this application exhibit stable properties, making it easier to control their geometry or dimensions during device fabrication. Furthermore, organic polymer materials are inexpensive and can be mass-produced and applied in large batches.

[0096] In some embodiments of this application, the radiant layer material on one side of the heat flow regulating device includes boron nitride, silicon carbide, silicon dioxide, lithium fluoride, silver chloride, magnesium oxide, barium fluoride, etc., thereby enhancing the radiative heat flow at the heat source end by utilizing the evanescent mode of the material surface. The radiant layer material on the other side of the heat flow regulating device includes intrinsic silicon, etc.

[0097] In some embodiments of this application, the radiating layer material on one side of the heat flow regulating device includes hexagonal boron nitride, cubic boron nitride, etc., while the radiating layer material on the other side of the heat flow regulating device includes indium antimonide, gallium arsenide, indium gallium arsenide, etc. The metal reflective layer includes gold, silver, aluminum, copper, chromium, zinc, iron, nickel, etc.

[0098] Exemplary embodiments of this application will now be described in more detail; however, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art. Furthermore, the materials used in the following embodiments include any type, purity, etc., conventional in the art, and the equipment used includes any type conventional in the art.

[0099] Example 1

[0100] This invention provides a method for applying a radiative heat flux control device to a near-field thermal diode. The thermal diode consists of two flat plates, with intrinsic silicon and lithium hydride as the radiating layer materials. In practical applications, since lithium hydride requires substrate support and the manufacturing process must be considered, a high-resistivity silicon substrate is chosen. The corresponding temperatures for the two plates are 900K and 300K, respectively.

[0101] This embodiment explores the technical effects achieved by adding an organic polymer layer between lithium hydride and high-resistivity silicon.

[0102] like Figure 9 , Figure 10 , Figure 11 , Figure 12 As stated, in which Figure 9 It does not contain an organic polymer layer. Figure 10 An organic polymer layer containing polydimethylsiloxane (PDMS), Figure 11 An organic polymer layer containing polyethylene (PE), Figure 12 An organic polymer layer containing polyimide (PI) is included, with each organic polymer layer having a thickness of 5 μm. The high-resistivity silicon layer has a thickness of 15 μm.

[0103] Combination Figure 9 , Figure 13 It can be seen that for thermal diodes without an organic polymer layer, the frequency is 2.1 × 10⁻⁶. 14 Near rad / s, due to the excitation of phonon polaritons on the lithium hydride surface, the electromagnetic localized state density reaches as high as 4 × 10⁻⁶. 5 Magnitude.

[0104] Although high-resistivity silicon substrates lack surface phonon polaritons that match lithium hydride, they support surface plasmon polaritons excited at high frequencies, above 2.1 × 10⁻⁶.14 The contribution of the electromagnetic localized density of states in the rad / s spectral range originates from the s-polarized evanescent wave. This portion of the electromagnetic localized density of states couples with the surface modes of lithium hydride, and then with the surface plasmon polaritons of the intrinsic silicon structure on the other side of the near-field thermal radiation diode. Since the contrast of the localized electromagnetic density of states provided by the intrinsic silicon structure on the other side under different temperature gradients is very low at high frequencies, the high-resistivity silicon on the lithium hydride side absorbs a large portion of the thermal radiation energy under different temperature gradients. This results in little difference between the forward and reverse heat flows of the thermal diode at high frequencies, which is detrimental to the overall rectification ratio of the thermal diode.

[0105] Combination Figures 10 to 12 and Figure 13 It can be seen that after introducing an organic polymer layer between lithium hydride and high-resistivity silicon, the frequency is higher than 2.1 × 10⁻⁶. 14 The local electromagnetic state density contributed by the high-resistivity silicon substrate in the rad / s range is significantly suppressed, reduced by about one order of magnitude. Therefore, the thermal radiation absorption caused by the high-resistivity silicon substrate is significantly reduced. At the same time, the introduction of an organic polymer spacer layer enhances the energy density in the surface wave region of the lithium hydride material, which can better filter the contrast of local electromagnetic state densities provided by the intrinsic silicon on the other side under different temperature gradients, thus achieving a higher rectification ratio.

[0106] Furthermore, the performance of a radiative thermal diode is described by its rectification ratio, which is expressed as follows:

[0107]

[0108] Where, in the formula and Let be the total radiative heat flow in the forward and reverse directions of the thermal diode, respectively. Based on the theory of fluctuation electrodynamics, the formula for calculating the radiative heat flow between two parallel planar structures is:

[0109]

[0110] in, , The transmission coefficients for s and p biases can be calculated from Fresnel reflection and transmission coefficients.

[0111] This embodiment can calculate its specific value according to the above formula for calculating the rectification ratio.

[0112] This embodiment further explores the effect of vacuum spacing on radiative heat flux, such as Figure 14 As shown, the radiative heat flow at an intrinsic silicon end temperature of 900K is a forward heat flow, and the radiative heat flow at an intrinsic silicon end temperature of 300K is a reverse heat flow. Figure 14The solid line represents the forward radiative heat flow, and the dashed line represents the reverse radiative heat flow. For both forward and reverse radiative heat flows, the introduction of the organic polymer layer increases the radiative heat flow at different vacuum gaps, but the increase in forward radiative heat flow is greater than that in reverse radiative heat flow. Therefore, it can be concluded without a doubt that the rectification ratio of the forward radiative heat flow is greater than that of the reverse radiative heat flow. Because the organic polymer layer material introduced in this application has high transmittance in the far-infrared, mid-infrared, near-infrared, and visible light frequencies, it reduces the evanescent wave energy transferred from the high-resistivity silicon surface to the lithium hydride, reducing its coupling with the surface plasmon polaritons of the intrinsic silicon structure on the other side of the near-field thermal radiation diode. Simultaneously, this organic polymer layer material does not support or supports very weak surface polaritons, resulting in a mismatch with the local electromagnetic density of states of lithium hydride, thus achieving the characteristic of radiative spectral mismatch. The filtering effect of the local electromagnetic state density in the lithium hydride surface wave band on the contrast of the local electromagnetic state density provided by the intrinsic silicon structure on the other side of the near-field thermal radiation diode under different temperature gradients will maximize the rectification ratio.

[0113] Table 1 shows the thermal rectification examples of the thermal diode in this embodiment at a vacuum spacing of 50nm~100nm:

[0114] Table 1 Performance List of Thermal Diodes

[0115]

[0116] Combination Figure 15 It is evident that the forward heat flow varies significantly with the vacuum spacing, implying that surface phonon polaritons of lithium hydride still dominate under forward heat flow conditions, with the organic polymer spacer layer making a positive contribution. However, in reverse heat flow, the vacuum spacing has little effect on the heat flow. This may be because even though the organic material increases the radiative energy absorbed by lithium hydride, this contribution does not originate from the surface phonon polaritons of lithium hydride and is independent of the vacuum spacing. It may instead originate from the mode coupling between the organic polymer material and intrinsic silicon. Due to the low absorption of the organic polymer material at high frequencies and its obstruction of the radiative heat absorption channels of the high-resistivity silicon substrate, this mode contributes significantly more to the forward heat flow than to the reverse heat flow.

[0117] As shown in Table 1, the thermal diode containing PDMS has the best rectification ratio, while the rectification ratios of the thermal diode containing PE and the thermal diode containing PI are similar. Overall, the rectification ratio decreases as the spacing increases. This is likely because as the spacing increases, the energy contribution from mode coupling and evanescent wave tunneling between lithium hydride and intrinsic silicon weakens.

[0118] Combination Figure 16 It can be seen that the rectification ratio of a thermal diode containing an organic polymer layer increases with the increase of the vacuum gap.

[0119] Example 2

[0120] A device for controlling radiative heat flux is provided for use in near-field thermophotovoltaics. This thermophotovoltaic system consists of two flat plates, with hexagonal boron nitride and indium antimonide as the radiating layer materials. In practical applications, since hexagonal boron nitride requires substrate support and the processing technology must be considered, doped silicon is chosen as the substrate. A gold reflective layer is also provided on the indium antimonide side to recover low-energy photons that cannot be utilized by indium antimonide.

[0121] The temperatures of the two plates are 500K and 300K, respectively.

[0122] The thickness of the hexagonal boron nitride layer can be selected from 10nm, 30nm, 50nm, and 100nm; the indium antimonide layer thickness is 1μm; the intrinsic silicon at the high-temperature end is 15μm; and the gold reflective layer at the indium antimonide end is 150nm thick. The spacing is 10nm. Taking polyimide (PI) material as an example, the hexagonal boron nitride organic polymer interlayer has a thickness of 10μm. The specific structure is as follows... Figure 17 , Figure 18 Indication.

[0123] The thermal radiation spectrum of a thermophotovoltaic cell without an organic polymer layer exhibits a typical electromagnetic interference effect due to the gold reflective layer, meaning that the absorption of radiative thermal energy from the gold reflective layer is significant. Only radiative thermal energy above the indium antimonide bandgap can be converted into electrical energy by indium antimonide. By introducing a polyimide (PI) spacer layer, the thermal radiation spectrum of this photovoltaic cell is significantly altered, and the interference effect from the gold reflective layer is greatly suppressed, especially in the radiation spectrum above the indium antimonide bandgap, resulting in an overall enhanced radiation intensity.

[0124] Combination Figure 19 , Figure 20 It can be seen that the total radiative heat flux and output power of thermophotovoltaics without the organic polymer layer are both lower than those with the organic polymer layer. Meanwhile, with the increase of hexagonal boron nitride thickness, the total radiative heat flux and output power of both types of thermophotovoltaics increase. After introducing the organic polymer spacer layer, the output power increases from 683 W / m. 2 Effectively increased to 692W / m 2 .

[0125] Based on fluctuation electrodynamics, the expression for the output power density of near-field thermophotovoltaics is:

[0126]

[0127] Where, in the formula The band gap of a photovoltaic cell at the low-temperature end in thermophotovoltaics is the energy radiated above this band gap that is converted into electrical energy and utilized by an external circuit.

[0128] In this embodiment, with a hexagonal boron nitride thickness of 100 nm, the above calculation method was used to obtain the output power and energy conversion efficiency of the thermophotovoltaic power, as shown in Table 2.

[0129] Table 2 Performance List of Thermal Photovoltaics

[0130]

[0131] In summary, the radiation heat flow control device provided in this application is beneficial for improving the heat rectification ratio of the thermal rectifier and improving the output power and energy conversion efficiency of the thermophotovoltaic device.

[0132] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A radiative heat flux regulating device, characterized in that: It includes at least two radiators arranged opposite each other, each of which includes a radiating layer; The two radiators arranged opposite each other have a vacuum gap, which is not greater than the thermal characteristic wavelength of the device at low temperature. At least one radiator comprises a substrate and one or more organic polymer layers, the organic polymer layers being located between the substrate and the radiating layer to reduce radiation absorption by materials other than the radiating layer; The radiator further includes an intermediate layer, which is also located between the substrate and the radiating layer; The organic polymer layer is configured in any of the following ways: (2.1) The organic polymer layer is located between the intermediate layer and the radiation layer; (2.2) The organic polymer layer is located between the intermediate layer and the base layer.

2. The device according to claim 1, characterized in that: The organic polymer layer either does not support surface polaritogenic properties or supports weak surface polaritogenic properties; the organic polymer layer satisfies one or more of the following combinations: (1.1) The organic polymer layer contains a molecular weight of 10 4 ~10 6 One or a combination of two of the following: carbon polymers or SU-8 photoresist; (1.2) The thickness of the organic polymer layer is not less than the thickness of the radiation layer; (1.3) The thickness of the organic polymer layer is not greater than the thickness of the substrate.

3. The device according to any one of claims 1 to 2, characterized in that: The organic polymer layer comprises one or more of the following: polydimethylsiloxane, poly(p-xylenedicarboxylate), polyimide, polyethylene, polymethyl methacrylate, and SU-8 negative photoresist.

4. The device according to any one of claims 1 to 2, characterized in that: The thickness of the organic polymer layer is less than 10 μm.

5. The device according to claim 1, characterized in that: The radiation layer, substrate, and intermediate layer satisfy one or two of the following: (3.1) At least one of the radiation layer, the substrate, and the intermediate layer has the property of supporting surface polaritons; (3.2) One or more of the radiating layer, substrate, and intermediate layer contain any one of polar dielectric, metal, and semiconductor; The polar dielectric comprises one or more of cubic boron nitride, hexagonal boron nitride, lithium hydride, lithium fluoride, cesium fluoride, silicon carbide, silicon dioxide, silver chloride, magnesium oxide, barium fluoride, indium antimonide, gallium arsenide, and indium gallium arsenide. The metal comprises one or more of the following: gold, silver, aluminum, copper, chromium, zinc, iron, and nickel. The semiconductor comprises one or more of indium arsenide, doped silicon, high-resistivity silicon, intrinsic silicon, gallium, selenium, indium, tin, and tellurium.

6. The device according to claim 1, characterized in that: The vacuum spacing is 10nm~10μm.

7. The device according to claim 1, 2, 5, or 6, characterized in that: The substrate includes a groove structure formed after etching.

8. A heat flow regulating device, characterized in that: The heat flow regulating device comprises the device according to any one of claims 1 to 7; The heat flow regulating device includes any one of the following: thermal diode, thermal triode, thermal photovoltaic, thermal switch, thermal imager, and thermal lithography.

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