Optical filter for thermal photovoltaics and method for designing the same

Abstract

The application discloses a filter stack structure for thermal photovoltaics and a design method thereof, and relates to the field of thermal photovoltaics, and comprises a stack structure, the stack structure comprises a substrate, a metal layer and a dielectric layer; the dielectric layer is divided into a first part and a second part by the metal layer. A dielectric material is stacked on the substrate to construct several Fabry-Perot resonance modes; based on induced transmission, a metal layer is inserted at a minimum electric field of a wavelength in the stacked dielectric material, part of thermal radiation within the battery band gap V is transmitted, and thermal radiation outside the battery band gap V is reflected; based on an output model of a thermal photovoltaic cell and the influence of the metal layer on a spectrum, the thickness and the insertion position of the metal layer are optimized to realize efficient regulation of the thermal radiation spectrum.

Description

Technical Field

[0001] This invention relates to the field of thermophotovoltaics, and in particular to a filter for thermophotovoltaics and its design method. Background Technology

[0002] Thermophotovoltaics (TPV) is a highly efficient thermoelectric conversion technology based on the photovoltaic effect. The core components of a TPV system are a thermal radiator and a thermophotovoltaic cell. The thermal radiator absorbs energy from a heat source and emits it as thermal radiation to the thermophotovoltaic cell. The thermophotovoltaic cell absorbs thermal radiation with wavelengths shorter than its bandgap and generates a large number of electron-hole pairs, thus producing electricity. To improve the efficiency of TPV systems, spectral modulation of the thermal radiation is an effective measure. This involves suppressing the emission of thermal radiation with wavelengths longer than the bandgap or reflecting thermal radiation with wavelengths longer than the bandgap back to the thermal radiator, thereby achieving energy recovery. To achieve this spectral modulation, filters made of alternating materials can be constructed based on the interference principle, or metal antenna filters can be designed based on resonant transmission. This allows for high transmission of thermal radiation with wavelengths shorter than the thermophotovoltaic cell's bandgap and high reflection of thermal radiation with wavelengths longer than the bandgap, thereby improving the efficiency of the TPV system. However, alternating material filters based on the interference principle typically require a large number of layers to achieve efficient spectral modulation, resulting in significant structural limitations. Filters based on metal antenna structures require fabrication of micro- and nano-scale patterned structures on metal materials, making it difficult to suppress the absorption of thermal radiation energy. A large number of structural layers or complex patterned structures increases the spectral angular sensitivity, fabrication complexity, structural stability, and processing cost. Simultaneously, the absorption of thermal radiation by some filters themselves reduces their spectral modulation performance, hindering their application in thermophotovoltaic systems. Therefore, this study designs a low-layer filter structure to significantly improve thermophotovoltaic conversion efficiency. Through extensive data analysis and experimental observation, the study determines the directions for filter improvement, aiming to adjust and amplify the filter's characteristics while increasing the transmission of thermal radiation with wavelengths shorter than the bandgap wavelength and the reflection of thermal radiation with wavelengths longer than the bandgap wavelength, all while maintaining strong adaptability. Summary of the Invention

[0003] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this section, the abstract and title of the invention. Such simplifications or omissions shall not be used to limit the scope of the present invention.

[0004] Given that the aforementioned and / or existing technologies using alternating material filters based on interference principles typically require a large number of layers to achieve efficient spectral modulation, resulting in significant structural limitations, and that filters based on metal antenna structures require fabrication of micro- and nano-scale patterned structures on metal materials, making it difficult to suppress the absorption of thermal radiation energy by the filter. The increased number of structural layers or complex patterned structures increases the spectral angular sensitivity, fabrication complexity, structural stability, and fabrication cost. Furthermore, the absorption of thermal radiation by some filters themselves reduces their spectral modulation performance, hindering the application of filters in thermophotovoltaic systems. Therefore, this invention is proposed.

[0005] Therefore, the technical problem to be solved by the present invention is to design a low-layer filter structure that can significantly improve the thermo-photovoltaic conversion efficiency.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a filter stacked structure for thermophotovoltaics, comprising a stacked structure, wherein the stacked structure includes a substrate, a metal layer, and a dielectric layer;

[0007] The dielectric layer is divided into a first part and a second part by the metal layer.

[0008] As a preferred embodiment of the filter stack structure for thermophotovoltaics described in this invention, the first part and the second part of the dielectric layer are a single layer of dielectric material or a structure of alternating stacks of dielectric materials with different refractive indices, and the sum of the number of material layers in the first part and the second part is 3 to 5 layers.

[0009] As a preferred embodiment of the filter stack structure for thermophotovoltaics described in this invention, the substrate is a thermophotovoltaic cell or a transparent material or composite structure in the 1-2.5μm wavelength range.

[0010] As a preferred embodiment of the filter stack structure for thermophotovoltaics described in this invention, the metal layer is a metal material with a thickness of 10nm to 40nm, and the metal layer has a reflectivity of greater than 90% in the 2 to 10μm wavelength band.

[0011] As a preferred embodiment of the filter stack structure for thermophotovoltaics described in this invention, the first part has a maximum absorption rate of less than 2% in the 0.6–8 μm band.

[0012] As a preferred embodiment of the filter stack structure for thermophotovoltaics described in this invention, the contact surface between the substrate and the dielectric layer is parallel to the contact surfaces of the other layers.

[0013] As a preferred embodiment of the filter stack structure for thermophotovoltaics described in this invention, the substrate is a GaSb battery substrate;

[0014] Both the first and second parts are composed of ZnS;

[0015] The metal layer is Ag.

[0016] In a preferred embodiment of the filter stack structure for thermophotovoltaics described in this invention, the thickness of the metal layer is 10–30 nm.

[0017] The thickness of the first part is 130–160 nm;

[0018] The thickness of the second part is 260–400 nm.

[0019] The beneficial effects of this invention are: a filter with energy conversion characteristics matching that of a thermophotovoltaic cell is designed, which improves the thermophotovoltaic efficiency while reducing the structural complexity of the filter and improving the angular insensitivity and processing robustness of the filter's spectral characteristics.

[0020] Given the need for extensive data analysis and experimental observation of the thermo-photovoltaic conditions of filters and their applications, the materials and thicknesses of each layer in the filter stack structure are determined, and the filter design is completed.

[0021] Therefore, the technical problem to be solved by the present invention is to design and optimize the structure of the filter by combining the thermophotovoltaic cell model, so as to enhance the matching degree between the radiation characteristics of the filter and the energy conversion characteristics of the thermophotovoltaic cell, that is, to increase the thermal radiation transmission with wavelengths smaller than the bandgap wavelength and increase the thermal radiation reflection with wavelengths larger than the bandgap wavelength.

[0022] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a filter design method for thermophotovoltaics, comprising stacking dielectric materials on the substrate to construct a plurality of Fabry-Perot resonant modes;

[0023] Based on induced transmission, a metal layer is inserted at the point of minimum electric field of wavelength in the stacked dielectric material to transmit part of the thermal radiation within the cell bandgap V and reflect the thermal radiation outside the cell bandgap V.

[0024] Based on the output model of thermophotovoltaic cells and the influence of metal layers on the spectrum, the thickness and insertion position of the metal layer are optimized, and finally, efficient control of thermal radiation spectrum is achieved.

[0025] As a preferred embodiment of the filter design method for thermophotovoltaics described in this invention, the transmission peak wavelength λ1, which is close to and smaller than the cell bandgap V on the dielectric structure, is selected, and the other wavelength range is λ2.

[0026] A metal layer is inserted at the point of minimum electric field corresponding to the transmission peak wavelength λ1, and thermal radiation is induced to be transmitted through the dielectric structure.

[0027] Within the wavelength range λ2, thermal radiation is reflected in the stacked structure (100).

[0028] As a preferred embodiment of the filter design method for thermophotovoltaics described in this invention, wherein: when the number of layers in the stacked structure is four, that is, when the second part is composed of upper and lower layers of dielectric material:

[0029] The substrate is ZnS;

[0030] The metal layer is Ag with a thickness of 10–30 nm;

[0031] The first part is ZnS with a wavelength of 80–200 nm;

[0032] The upper dielectric material is ZnS with a wavelength of 90–150 nm;

[0033] The underlying dielectric material is MgF2 with a wavelength of 260–400 nm;

[0034] Combining the four-layer stacked structure with a 1400℃ blackbody radiator and a GaSb cell, the thermophotovoltaic efficiency is 24.0%.

[0035] When the incident angle is 0° to 60°, the directional spectral radiative power transmitted by the stacked structure (100) will not significantly deviate from the design spectrum, with a peak shift of only 132 nm.

[0036] Considering the thickness processing errors of the metal layer and the dielectric layer are ±15% and 5% respectively, the stacked structure has a 50% probability of achieving an absolute efficiency reduction of no more than 0.12% and a 90% probability of obtaining a thermo-photovoltaic efficiency of more than 23.67%.

[0037] The beneficial effects of this invention are: the improved filter has a simple structure, good spectral control performance, spectral angle insensitivity, and processing robustness, which is of great value for promoting the large-scale application of thermophotovoltaics. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0039] Figure 1 A schematic cross-sectional view of a filter for thermophotovoltaics according to an embodiment of the present invention;

[0040] Figure 2A schematic diagram illustrating the relationship between the thickness and position of the metal layer and the efficiency in a three-layer induced transmission filter, as described in an embodiment of the present invention, for a filter design method for thermophotovoltaics.

[0041] Figure 3 A schematic diagram of the electric field distribution in the dielectric structure of a three-layer induced transmission filter, which is a design method for a filter used in thermophotovoltaics according to an embodiment of the present invention.

[0042] Figure 4 A schematic diagram of the spectrum of a three-layer induced transmission filter for thermophotovoltaics, as described in an embodiment of the present invention;

[0043] Figure 5 A schematic diagram of a preferred four-layer filter cross-sectional structure for a filter design method for thermophotovoltaics according to an embodiment of the present invention;

[0044] Figure 6 A schematic diagram illustrating the relationship between the transmission spectrum of the dielectric structure and the dielectric thickness in a preferred four-layer filter design method for thermophotovoltaics, as provided in an embodiment of the present invention.

[0045] Figure 7 A preferred four-layer filter spectrum diagram of a filter design method for thermophotovoltaics provided in an embodiment of the present invention;

[0046] Figure 8 A schematic diagram of the photovoltaic radiation force of a preferred four-layer filter according to an embodiment of the present invention for designing a filter for thermophotovoltaics;

[0047] Figure 9 This is a schematic diagram illustrating the efficiency distribution probability of a preferred four-layer filter structure for a thermophotovoltaic filter design method according to an embodiment of the present invention under processing errors. Detailed Implementation

[0048] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0049] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0050] Secondly, the present invention will be described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure will be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0051] Furthermore, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that mutually excludes other embodiments.

[0052] Example 1

[0053] Reference Figure 1 This embodiment provides a filter for thermophotovoltaics, including a stacked structure 100, which corresponds to the composition state of the filter. The filter body includes a substrate 101, a metal layer 102, and a dielectric layer 103.

[0054] Furthermore, the substrate 101 is used for the deposition or transfer of other parts. The substrate 101 is a thermophotovoltaic cell or a transparent material or composite structure in the 1-2.5μm wavelength range. The substrate 101 can be a glass substrate, a silicon substrate, a germanium substrate, or a coating structure of the above substrates, with many options available.

[0055] Furthermore, the dielectric layer 103 is directly deposited on the substrate 101, and the resulting dielectric structure and environment can form several resonant cavities, with several transmission peaks in its spectrum.

[0056] Furthermore, the metal layer 102 is located within the dielectric layer 103 and is divided into a first part 103a and a second part 103b. The thickness and position of the metal layer affect the spectral characteristics of the filter.

[0057] Furthermore, based on the principle of induced transmission, high transmission at the designed wavelength and high reflection in other wavelength ranges can be achieved, thereby improving the efficiency when combined with thermophotovoltaics.

[0058] Example 2

[0059] Reference Figure 1 This is the second embodiment of the present invention. This embodiment is based on the previous embodiment, and differs from the previous embodiment in that: the first part 103a and the second part 103b of the dielectric layer 103 is a single layer of dielectric material or a structure of alternating stacks of multiple layers of dielectric materials with different refractive indices. Under this interference, selective transmission is achieved. The sum of the number of material layers of the first part 103a and the second part 103b is 3 to 5 layers, and the multiple layers are combined to form multiple resonant cavities.

[0060] Example 3

[0061] Reference Figures 1-2 This is the third embodiment of the present invention. This embodiment is based on the previous embodiment, and differs from the previous embodiment in that: the metal layer 102 is a metal material with a thickness of 10nm to 40nm, and the reflectivity of the metal layer 102 in the 2 to 10μm band is greater than 90%.

[0062] In detail, the metal layer 102 is an external optimization component that directly affects the thermo-photovoltaic efficiency. Its thickness and position are important factors that determine the spectral properties of the filter. In the 10nm to 40nm range, the metal layer 102 can exhibit good selective light transmission performance. The reflectivity of 2 to 10μm band is greater than 90%, which also determines that the filter can efficiently reflect thermal radiation with wavelengths greater than the cell bandgap in this band, thereby achieving energy recovery and efficiency improvement.

[0063] Example 4

[0064] Reference Figures 1-2 This is the fourth embodiment of the present invention, which is based on the previous embodiment, but differs from the previous embodiment in that the maximum absorption rate of the first part 103a in the 0.6-8μm wavelength band is less than 2%. This also means that the absorption rate of the filter is not high in a wide wavelength range, and the impact of the filter's own absorption on the efficiency is greatly reduced.

[0065] Example 5

[0066] Reference Figure 1 This is the fifth embodiment of the present invention. This embodiment is based on the previous embodiment, and differs from the previous embodiment in that: the contact surface between the substrate 101 and the dielectric layer 103 is parallel to the contact surfaces of the other layers. The contact surface between the substrate 101 and the second part 103b is shown as a plane in the figure, but its shape is not limited to this and can be a curved surface including a sphere, an ellipse, a cylinder, a parabola, etc., and the contact surfaces of the other layers are parallel to the contact surface between the substrate 101 and the third part 103b.

[0067] Example 6

[0068] Reference Figure 1 This is the sixth embodiment of the present invention. This embodiment is based on the previous embodiment, and the difference from the previous embodiment is that the substrate 101 is composed of a GaSb battery substrate.

[0069] The components of Part 103a and Part 103b are ZnS;

[0070] Metal layer 102 is Ag;

[0071] These materials and components can be modified according to the needs of the thermophotovoltaic system application. The use of Ag in the metal layer 102 is due to the fact that Ag has a reflectivity of more than 98% in the 2-10μm band, which can efficiently reflect thermal radiation with a wavelength greater than the bandgap wavelength of the battery, thereby improving the thermophotovoltaic efficiency.

[0072] Example 7

[0073] Reference Figure 1 This is the seventh embodiment of the present invention. This embodiment is based on the previous embodiment, but differs from the previous embodiment in that the thickness of the metal layer 102 is 10-30 nm. With this thickness, the thermal radiation spectrum can be efficiently controlled, and the thermophotovoltaic efficiency is significantly improved.

[0074] The thickness of the first part 103a is 130–160 nm;

[0075] The thickness of the second part, 103b, is 260–400 nm.

[0076] The thickness of the entire dielectric layer 103 is within this range, resulting in high transmittance to thermal radiation and high thermo-photovoltaic efficiency.

[0077] Example 8

[0078] Reference Figures 1-4 This is the eighth embodiment of the present invention. This embodiment provides a design method for a filter for thermophotovoltaics. This embodiment is based on the previous embodiment, but differs from the previous embodiment in that: a dielectric material is stacked on the substrate 101 to construct several Fabry-Perot FP resonant modes;

[0079] Based on induced transmission, a metal layer 102 is inserted at the point of minimum electric field at a specific wavelength within the stacked dielectric material. This preserves the selective transmission peak within the cell's bandgap and reflects thermal radiation outside the bandgap, as shown in the electric field distribution. Figure 3 As shown, the transmission of thermal radiation occurs within the bandgap V of the battery, while the reflection of thermal radiation occurs outside the bandgap V.

[0080] Based on the output model of the thermophotovoltaic cell and the influence of the metal layer on the spectrum, the thickness and insertion position of the metal layer 102 are optimized to achieve efficient control of the thermal radiation spectrum.

[0081] The entire process for regulating and optimizing the radiation spectrum of the thermophotovoltaic filter is as described above.

[0082] In detail, the wavelength corresponding to the FP mode can be obtained from... Determine, where n s Let d be the refractive index of the dielectric layer. s Where is the thickness of the dielectric layer, and m is the order of the FP mode;

[0083] In detail, there are several options for the structure of the entire filter, each of which can reflect efficient control of thermal radiation within a certain range. The simplest model is a three-layer induced transmission filter, which only includes a substrate 101, a dielectric layer 103, and a dielectric layer. In this case, the induced transmission filter has only three layers, such as... Figure 1 As shown;

[0084] In detail, without considering the metal layer 102 in the three-layer induced transmission filter, the dielectric layer 103 consists of a first part 103a and a second part 103b. The dielectric structure and the environment can form a resonant cavity composed of "air-zinc sulfide-GaSb", which can form FP modes located in the zinc sulfide layer at different wavelengths and form several transmission peaks.

[0085] Furthermore, based on the principle of induced transmission, a transmission peak with a wavelength around 1.2 μm within the bandgap is selected, and an ultrathin silver layer is inserted at the point of minimum structural electric field distribution at the corresponding wavelength. At this point, the silver layer is located near the local minimum of the electric field in the dielectric layer within the 1-2.5 μm band, thus having minimal impact on the electric field. Thermal radiation in this band is primarily transmitted through the stacked structure of the first and second parts, forming induced transmission. Thermal radiation in other bands has a larger electric field at the Ag layer and is therefore significantly affected by the Ag layer. Since Ag's optical properties are primarily reflection, thermal radiation in other bands is primarily reflected. Ultimately, the filter can achieve high reflectivity for thermal radiation with wavelengths greater than the bandgap wavelength while transmitting thermal radiation with wavelengths smaller than the bandgap wavelength, achieving efficient spectral modulation for thermophotovoltaic cells.

[0086] Furthermore, since the electric field at the metal insertion point cannot be completely zero, the metal layer has a certain influence on the structure's spectrum. To account for this influence, the thickness and insertion position of the nanoscale metal layer can be optimized based on the output model of a thermophotovoltaic cell, with thermophotovoltaic efficiency as the target, thereby achieving efficient control of the thermal radiation spectrum and completing the design of a few-layer filter. When this three-layer filter structure is applied to a TPV system, combined with a 1400℃ blackbody and GaSb cell, the relationship between its thermophotovoltaic efficiency and the position and thickness of the metal layer is as follows: Figure 2 As shown.

[0087] Specifically, Figure 4 The transmission, reflection, and absorption spectra of the filter are calculated based on the above scheme.

[0088] Specifically, if the above three-layer induced transmission filter is applied to a thermophotovoltaic system and combined with a 1400℃ blackbody radiator and GaSb cell, the thermophotovoltaic efficiency can be significantly improved from 8.8% to 22.56%.

[0089] Example 9

[0090] Reference Figures 1-9 This is the ninth embodiment of the present invention. This embodiment is based on the previous embodiment, but differs from the previous embodiment in that: when the stacked structure 100 has four layers, that is, when the second part is composed of two layers of dielectric material: another structural model for the thermophotovoltaic induced transmission filter is a four-layer induced transmission filter, that is, in addition to the two parts containing the substrate 101 and the dielectric layer 103, the second part 103b is further divided into upper and lower layers, the upper layer is assumed to be U and the lower layer is D, as shown below. Figure 5 In this case, excluding the induced transmission filter, the number of layers is 4; the 4-layer stacked structure 100 and the metal layer 102 are composed as follows:

[0091] Substrate 101 is ZnS;

[0092] Metal layer 102 is Ag with a thickness of 10–30 nm;

[0093] The first part, 103a, is ZnS with a wavelength of 80–200 nm.

[0094] The upper dielectric material U is ZnS with a wavelength of 90–150 nm;

[0095] The underlying dielectric material D is MgF2 with a wavelength of 260–400 nm;

[0096] In detail, disregarding the metal layer 102 in the four-layer induced transmission filter, the substrate 101 and the dielectric layer 103 constitute a dielectric structure. This dielectric structure and its environment can form two resonant cavities consisting of "air-zinc sulfide-magnesium fluoride" and "zinc sulfide-magnesium fluoride-substrate," respectively. FP modes can be formed at different wavelengths and distributed within the zinc sulfide and magnesium fluoride layers, respectively, resulting in several transmission peaks. Simultaneously, when the wavelengths of the modes distributed in the two layers are similar, mode splitting occurs, causing the two modes to shift away from each other's wavelengths. Based on the principle of induced transmission, a transmission peak with a wavelength around 1 μm within the bandgap is selected, and an ultrathin silver layer is inserted at the point of minimum structural electric field distribution at its corresponding wavelength. Similarly, for the three-layer filter structure, the silver layer has the least influence on the electric field in the 1-2.5 μm band, exhibiting transmission characteristics. Thermal radiation in other bands results in a larger electric field at Ag, exhibiting reflection characteristics.

[0097] It is important to note that, because the FP resonant modes in the four-layer induced transmission filter structure can be localized in two layers, the mode splitting phenomenon caused by the coupling of FP modes between different layers needs to be considered. That is, the positions of the two modes will deviate from their individual positions in a direction away from each other. Figure 6 As shown.

[0098] Figure 7The transmission, reflection, and absorption spectra of the filter are calculated based on the above scheme. For gallium antimonide (GaS) batteries, the bandgap wavelength is 1.72 micrometers, while the filter exhibits a significant transmission peak in the 0.7-1.72 micrometer range. Simultaneously, it displays a reflectivity greater than 98% in wavelengths greater than 1.72 micrometers, and the maximum absorption peak value is less than 4% in the 0.5-10 micrometer range. Therefore, when the filter is applied to a thermophotovoltaic system, it will reflect over 98% of the thermal radiation with wavelengths greater than 1.72 micrometers—that is, thermal radiation that cannot be converted into electrical energy by the battery—to the thermal radiator, thereby achieving energy recovery and improving the efficiency of the thermophotovoltaic system.

[0099] Specifically, by applying a four-layer induced transmission filter to a thermophotovoltaic system in combination with a 1400℃ blackbody radiator and GaSb cells, the thermophotovoltaic efficiency can be improved from 8.8% to 24.0% compared to a system without filters.

[0100] Furthermore, regardless of whether it is a 3-layer or 4-layer structure, due to the fewer layers, the structural spectrum exhibits good angle insensitivity.

[0101] In detail, taking a 4-layer structure as an example, within the 0-60° range, the directional spectral radiance transmitted by the filter will not significantly deviate from the designed spectrum, with a peak shift of only 132nm. When the angle is greater than 60°, since the thermal radiation emitted by a blackbody follows Lambert's cosine law, the directional radiance will decrease with increasing angle. Therefore, the influence of the blue shift in directional spectral radiance with increasing angle will be weakened, resulting in the thermal radiation of the transmission filter mainly concentrated within the designed transmission band. Figure 8 As shown.

[0102] Furthermore, due to the fewer layers and simpler optical mechanism, the structural spectrum is less affected by processing errors in the thickness of each layer, thus exhibiting good fabrication robustness. Taking a 4-layer structure as an example, considering thickness errors of ±15% for the metal layer and 5% for the dielectric layer, applying the spectra of all combined structures to the same thermophotovoltaic system, the efficiency distribution is as follows: Figure 8 As shown, when the processed filter is combined with a 1400℃ blackbody radiator and a GaSb cell, there is a 50% probability that the absolute efficiency reduction will not exceed 0.12%, and a 90% probability that a thermophotovoltaic efficiency of over 23.67% can be achieved. Figure 9 As shown.

[0103] Example 10

[0104] Reference Figures 1-9 This is the tenth embodiment of the present invention. This embodiment is based on the previous embodiment, and the difference from the previous embodiment is that: the transmission peak wavelength λ1 on the dielectric structure 100 is close to and smaller than the cell band gap V, and the other wavelengths are λ2.

[0105] A metal layer 102 is inserted at the point of minimum electric field corresponding to the transmission peak wavelength λ1, and thermal radiation is induced to be transmitted through the dielectric structure 100.

[0106] Within the wavelength range λ2, thermal radiation is reflected in the stacked structure (100).

[0107] It is important to note that the constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible without substantially departing from the novel teachings and advantages of the subject matter described in this application (e.g., variations in the size, dimensions, structure, shape, and proportions of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), installation arrangements, use of materials, color, orientation, etc.). For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of elements may be inverted or otherwise changed, and the nature or number or position of discrete elements may be altered or changed. Therefore, all such modifications are intended to be included within the scope of the invention. The order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure performing the function described herein, and not only structurally equivalent but also equivalent in structure. Other substitutions, modifications, alterations, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments without departing from the scope of the invention. Therefore, the present invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0108] Furthermore, in order to provide a concise description of exemplary embodiments, not all features of actual embodiments may be described, i.e., those features that are not relevant to the currently considered best mode for carrying out the invention, or those features that are not relevant to implementing the invention.

[0109] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those of ordinary skill in the art who benefit from this disclosure, the development effort will be a routine task in design, manufacturing, and production without requiring extensive experimentation.

[0110] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A filter for thermophotovoltaics, characterized in that: include, The stacked structure (100) includes a substrate (101), a metal layer (102), and a dielectric layer (103). The dielectric layer (103) is divided into a first part (103a) and a second part (103b) by the metal layer (102); The first part (103a) and the second part (103b) of the dielectric layer (103) are a single layer of dielectric material or a structure of alternating stacks of dielectric materials with different refractive indices, and the sum of the number of material layers of the first part (103a) and the second part (103b) is 3 to 5 layers; The metal layer (102) is a metal material with a thickness of 10nm to 40nm, and the reflectivity of the metal layer (102) is greater than 90% in the 2 to 10μm wavelength band; A dielectric material is stacked on the substrate (101) to construct several Fabry-Perot (FP) resonant modes; Based on induced transmission, a metal layer (102) is inserted at the point of minimum electric field of wavelength in the stacked dielectric material to transmit part of the thermal radiation within the cell bandgap V and reflect the thermal radiation outside the cell bandgap V. Based on the output model of the thermophotovoltaic cell and the influence of the metal layer on the spectrum, the thickness and insertion position of the metal layer (102) are optimized to achieve efficient control of the thermal radiation spectrum.

2. A filter for thermophotovoltaics according to claim 1, characterized in that: The substrate (101) is a thermophotovoltaic cell or a transparent material or composite structure in the 1~2.5μm wavelength range.

3. A filter for thermophotovoltaics according to claim 2, characterized in that: The first part (103a) has a maximum absorption rate of less than 2% in the 0.6~8μm band.

4. A filter for thermophotovoltaics according to claim 3, characterized in that: The contact surface between the substrate (101) and the dielectric layer (103) is parallel to the contact surfaces of the other layers.

5. A filter for thermophotovoltaics according to claim 4, characterized in that: The substrate (101) is composed of GaSb battery substrate; Both the first part (103a) and the second part (103b) are composed of ZnS; The metal layer (102) is Ag.

6. A filter for thermophotovoltaics according to claim 5, characterized in that: The thickness of the metal layer (102) is 10~30nm; The thickness of the first part (103a) is 130~160nm; The second part (103b) has a thickness of 260~400nm.

7. A method for designing a filter for thermophotovoltaics, characterized in that: A filter for thermophotovoltaics according to any one of claims 1 to 6, and, A dielectric material is stacked on the substrate (101) to construct several Fabry-Perot (FP) resonant modes; Based on induced transmission, a metal layer (102) is inserted at the point of minimum electric field of wavelength in the stacked dielectric material to transmit part of the thermal radiation within the cell bandgap V and reflect the thermal radiation outside the cell bandgap V. Based on the output model of the thermophotovoltaic cell and the influence of the metal layer on the spectrum, the thickness and insertion position of the metal layer (102) are optimized to achieve efficient control of the thermal radiation spectrum.

8. The design method for a filter for thermophotovoltaics according to claim 7, characterized in that: The transmission peak wavelength λ1, which is close to and smaller than the cell band gap V in the dielectric structure, is selected, and the other wavelength range is λ2. A metal layer (102) is inserted at the point of minimum electric field corresponding to the transmission peak wavelength λ1, and thermal radiation is induced to be transmitted in the stacked structure (100); In the wavelength range λ2, thermal radiation is reflected in the stacked structure (100).

9. The design method for a filter for thermophotovoltaics according to claim 8, characterized in that: When the stacked structure (100) has four layers, that is, when the second part (103b) is composed of two layers of dielectric material: The substrate (101) is ZnS; The metal layer (102) is Ag with a thickness of 10~30 nm; The first part (103a) is ZnS with a wavelength of 80~200 nm; The upper dielectric material (U) is ZnS with a wavelength of 90~150 nm; The underlying dielectric material (D) is MgF2 with a wavelength of 260~400 nm; Combining the four-layer stacked structure (100) with a 1400℃ blackbody radiator and a GaSb cell, the thermophotovoltaic efficiency is 24.0%. When the incident angle is 0°~60°, the directional spectral radiative force shift design spectral amplitude transmitted by the stacked structure (100) is reduced; Considering the thickness processing errors of the metal layer and the dielectric layer are ±15% and 5% respectively, the stacked structure (100) has a 50% probability of achieving an absolute efficiency reduction of no more than 0.12% and a 90% probability of obtaining a thermo-photovoltaic efficiency of more than 23.67%.

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