Optical filter for thermophotovoltaic and design method thereof

Abstract

The invention discloses a thermophotovoltaic optical filter stacked structure and a design method thereof, and relates to the thermophotovoltaic field, the thermophotovoltaic optical filter stacked structure comprises a stacked structure, and the stacked 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. Dielectric materials are stacked on the substrate, and a plurality of Fabry-Perot resonance modes are constructed; based on induced transmission, inserting a metal layer at the minimum electric field of the designed wavelength in the stacked dielectric material to transmit part of thermal radiation in the cell band gap V and reflect thermal radiation outside the cell band gap V; based on an output model of the thermophotovoltaic cell and the influence of the metal layer on the spectrum, the thickness and the insertion position of the metal layer are optimized, and efficient regulation and control of the thermal radiation spectrum are achieved.

Description

Technical Field

[0001] The invention relates to the field of thermophotovoltaics, in particular to a filter used for thermophotovoltaics and a design method thereof. Background Art

[0002] Thermophotovoltaics is a highly efficient thermoelectric conversion technology based on the photovoltaic effect. The core components of the thermoelectric conversion system based on this technology are thermal radiators and thermophotovoltaic cells. The thermal radiators absorb energy from the heat source and emit it to the thermophotovoltaic cells in the form of thermal radiation. The thermophotovoltaic cells absorb thermal radiation with a wavelength less than the band gap wavelength of the cell and generate a large number of electron-hole pairs to generate electrical energy. In order to improve the efficiency of the thermophotovoltaic system, it is an effective measure to spectrally control the thermal radiation in the thermophotovoltaic system, that is, to suppress the emission of thermal radiation with a wavelength greater than the band gap wavelength, or to reflect thermal radiation with a wavelength greater than the band gap wavelength to the thermal radiator to achieve energy recovery. In order to achieve the above-mentioned thermal radiation spectral control, it is currently possible to construct a filter of alternating materials based on the interference principle or design a metal antenna filter based on resonant transmission to achieve high transmission of thermal radiation with a wavelength less than the band gap wavelength of the thermophotovoltaic cell and high reflection of thermal radiation with a wavelength greater than the band gap wavelength, thereby improving the efficiency of the thermophotovoltaic system. However, alternating material filters based on the interference principle usually require a large number of layers to achieve efficient spectral regulation, and are severely limited in structure. Filters based on metal antenna structures require processing of micro-nanoscale graphic structures on metal materials, which makes it difficult to suppress the filter's absorption of thermal radiation energy. More structural layers or complex graphic structures increase the spectral angle sensitivity, processing complexity, structural stability and processing cost. At the same time, the absorption of thermal radiation by some filters themselves also reduces its spectral regulation performance, hindering the application of filters in thermal photovoltaic systems. Therefore, a filter structure with a small number of layers is designed to greatly improve the thermal photovoltaic conversion efficiency. Through a large amount of data analysis and experimental observation of the filter, it is determined in which direction the filter should be improved. While adjusting and amplifying the characteristics of the filter, under the premise of strong adaptability, the transmission of thermal radiation with a wavelength less than the band gap wavelength is increased, and the reflection of thermal radiation with a wavelength greater than the band gap wavelength is increased. Summary of the invention

[0003] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract of the specification and the title of the invention of this application to avoid blurring the purpose of this section, the abstract of the specification and the title of the invention, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0004] In view of the fact that the alternating material filters based on the interference principle mentioned above and / or in the prior art usually require a large number of layers to achieve efficient spectral regulation and are severely limited in structure, the filters based on the metal antenna structure need to process micro-nanoscale graphic structures on the metal material, which makes it difficult to suppress the filter's absorption of thermal radiation energy. A large number of structural layers or complex graphic structures increase the angular sensitivity, processing complexity, structural stability and processing cost of its spectrum. At the same time, the absorption of thermal radiation by some filters themselves also reduces its spectral regulation performance, hindering the application of filters in thermal photovoltaic systems. The present invention is proposed.

[0005] Therefore, the technical problem to be solved by the present invention is to design a filter structure with few layers that can significantly improve the thermal photovoltaic conversion efficiency.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a filter stack structure for thermophotovoltaics, comprising: a stack structure, wherein the stack structure comprises a substrate, a metal layer, and a dielectric layer;

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

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

[0009] As a preferred solution of the filter stack structure for thermophotovoltaics described in the present invention, the substrate is a thermophotovoltaic cell or a material or composite structure that is transparent in the 1-2.5 μm band.

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

[0011] As a preferred solution of the filter stack structure for thermophotovoltaics described in the present invention, the maximum absorption rate of the first part in the 0.6-8 μm band is less than 2%.

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

[0013] As a preferred solution of the filter stack structure for thermophotovoltaics described in the present invention, wherein: the substrate component is a GaSb cell substrate;

[0014] The first part and the second part are both composed of ZnS;

[0015] The metal layer is Ag.

[0016] As a preferred solution of the filter stack structure for thermophotovoltaic described in the present invention, wherein: the thickness of the metal layer is 10 to 30 nm;

[0017] The thickness of the first portion is 130 to 160 nm;

[0018] The thickness of the second portion is 260-400 nm.

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

[0020] In view of the need for a large amount of data analysis and experimental observation of the thermal photovoltaic conditions of the filter and its application, the material and thickness of each layer in the filter stack structure are determined to complete the design of the filter.

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

[0022] To solve the above technical problems, the present invention provides the following technical solutions: A method for designing a filter for thermophotovoltaics, comprising: stacking dielectric materials on the substrate to construct a number of Fabry-Perot resonance modes;

[0023] Based on induced transmission, a metal layer is inserted at the minimum electric field of the designed wavelength in the stacked dielectric material to transmit part of the thermal radiation within the battery band gap V and reflect the thermal radiation outside the battery band gap V;

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

[0025] As a preferred solution of the method for designing a filter for thermophotovoltaics described in the present invention, wherein: a transmission peak wavelength λ1 close to and smaller than the cell band gap V is selected on the dielectric structure, and the other wavelength range is λ2;

[0026] Inserting an ultra-thin metal at the minimum electric field corresponding to the transmission peak wavelength λ1, so that thermal radiation is induced to be transmitted on the dielectric structure;

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

[0028] As a preferred solution of the method for designing a filter for thermophotovoltaic according to the present invention, when the stacked structure has four layers, that is, the second part is composed of two layers of dielectric materials:

[0029] The substrate is ZnS;

[0030] The metal layer is 10 to 30 nm of Ag;

[0031] The first part is 80 to 200 nm of ZnS;

[0032] The upper dielectric material is 90-150nm ZnS;

[0033] The lower dielectric material is 260-400nm MgF2;

[0034] The four-layer stacked structure is combined with a 1400°C black body radiator and a GaSb cell, and the thermophotovoltaic efficiency is 24.0%;

[0035] When the incident angle is 0° to 60°, the directional spectral radiation force transmitted by the stacked structure (100) will not significantly deviate from the designed spectrum, and the peak value deviation is only 132 nm.

[0036] When considering that 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 drop in efficiency of no more than 0.12%, and a 90% probability of obtaining a thermophotovoltaic efficiency of more than 23.67%.

[0037] The beneficial effects of the present invention are as follows: the improved filter has a simple structure and good spectral control performance, spectral angle insensitivity, and processing robustness, and is of great value in promoting the large-scale application of thermophotovoltaics. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

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

[0040] Figure 2A schematic diagram of the relationship between the thickness and position of the metal layer and the efficiency in a three-layer induced transmission filter in a design method for a thermophotovoltaic filter according to an embodiment of the present invention;

[0041] Figure 3 A schematic diagram of the electric field distribution of a dielectric structure in a three-layer induced transmission filter in a method for designing a filter for thermophotovoltaic according to an embodiment of the present invention;

[0042] Figure 4 A schematic diagram of a spectrum of a three-layer induced transmission filter for a method of designing a filter for thermophotovoltaic according to an embodiment of the present invention;

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

[0044] Figure 6 A schematic diagram showing the relationship between the transmission spectrum of the medium structure and the medium thickness in a preferred four-layer filter according to a design method for a thermophotovoltaic filter according to an embodiment of the present invention

[0045] Figure 7 A schematic diagram of a preferred four-layer filter spectrum for a method for designing a filter for thermophotovoltaic according to an embodiment of the present invention;

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

[0047] Fig. 9 A schematic diagram of the efficiency distribution probability of a preferred four-layer filter structure under processing errors in a design method for a thermophotovoltaic filter according to an embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0049] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0050] Secondly, the present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0051] Furthermore, the term "one 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 term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0052] Example 1

[0053] Reference Figure 1 This embodiment provides a filter for thermophotovoltaic, including a stacked structure 100, the stacked structure 100 is equivalent to the composition state of the filter, the body of the filter includes a substrate 101, a metal layer 102, and a dielectric layer 103;

[0054] Further, the substrate 101 is used for deposition or transfer of other parts. The substrate 101 is a thermophotovoltaic cell or a material or composite structure that is transparent in the 1-2.5 μm band. The substrate 101 can be a glass substrate, a silicon substrate, a germanium substrate, etc., or a coating structure given to the above substrates. There are many choices;

[0055] Furthermore, the dielectric layer 103 is directly deposited on the substrate 101 , and the dielectric structure and the environment formed thereby can form a plurality of resonant cavities, and the spectrum thereof has a plurality of transmission peaks.

[0056] Furthermore, the metal layer 102 is located in the dielectric layer 103 and divides it 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 formed, thereby improving its efficiency after being combined with thermophotovoltaics.

[0058] Example 2

[0059] Reference Figure 1 , which is the second embodiment of the present invention. This embodiment is based on the previous embodiment, and is different from the previous embodiment in that the first part 103a and the second part 103b of the dielectric layer 103 are a layer of dielectric material or a structure in which multiple layers of dielectric materials with different refractive indices are alternately stacked. Under this interference, selective transmission is achieved. The total 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 Figure 1-2 , which is the third embodiment of the present invention, is based on the previous embodiment, and is different 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 thermophotovoltaic efficiency. The thickness and position are important factors that determine the spectral properties of the filter. In the range of 10nm to 40nm, the metal layer 102 can exert good selective light transmittance. The reflectivity of the 2-10μm band is greater than 90%, which also determines that in this band, the filter can efficiently reflect thermal radiation with a wavelength greater than the battery band gap and achieve energy recovery and efficiency improvement.

[0063] Example 4

[0064] Reference Figure 1-2 , which is the fourth embodiment of the present invention, is based on the previous embodiment, and is different from the previous embodiment in that the maximum absorption rate of the first part 103a in the 0.6-8μm band is less than 2%. This also means that at wavelengths within a large range, the absorption rate of the filter is not high at this time, and the influence of the absorption of the filter itself on the efficiency is greatly reduced.

[0065] Example 5

[0066] Reference Figure 1 , which is the fifth embodiment of the present invention. This embodiment is based on the previous embodiment, and is different 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 remaining layers, and the contact surface between the substrate 101 and the second portion 103b is illustrated as a plane in the figure, but its shape is not limited to this, and can be a curved surface including a sphere, an ellipsoid, a cylinder, and a parabola, and the contact surfaces of the remaining layers are parallel to the contact surface between the substrate 101 and the third portion 103b.

[0067] Example 6

[0068] Reference Figure 1 , which is the sixth embodiment of the present invention, and this embodiment is based on the previous embodiment, and is different from the previous embodiment in that: the substrate 101 is a GaSb battery substrate;

[0069] The first part 103a and the second part 103b are composed of ZnS;

[0070] The metal layer 102 is Ag;

[0071] These materials and components can be changed according to the application requirements of the thermophotovoltaic system. The metal layer 102 uses Ag because of the reflectivity of Ag in the 2-10 μm band greater than 98%, which can efficiently reflect thermal radiation with a wavelength greater than the cell band gap wavelength, thereby improving the thermophotovoltaic efficiency.

[0072] Example 7

[0073] Reference Figure 1 , which is the seventh embodiment of the present invention, is based on the previous embodiment, and is different from the previous embodiment in that: the thickness of the metal layer 102 is 10 to 30 nm. Under this thickness, the metal layer can achieve efficient regulation of the thermal radiation spectrum, and the thermophotovoltaic efficiency is significantly improved;

[0074] The first portion 103a has a thickness of 130 to 160 nm;

[0075] The second portion 103b has a thickness of 260-400 nm;

[0076] When the thickness of the entire dielectric layer 103 is within this range, the transmittance to thermal radiation and the thermal photovoltaic efficiency are relatively high.

[0077] Example 8

[0078] Reference Figure 1 to Figure 4 , which is the eighth embodiment of the present invention, and this embodiment provides a design method for a filter for thermophotovoltaics. This embodiment is based on the previous embodiment, and is different from the previous embodiment in that: a dielectric material is stacked on a substrate 101 to construct a plurality of Fabry-Perot FP resonance modes;

[0079] Based on induced transmission, the metal layer 102 is inserted at the minimum electric field of the designed wavelength in the stacked dielectric material, thereby retaining the selective transmission peak within the battery band gap and reflecting the thermal radiation outside the band gap. The electric field distribution is as follows: Figure 3 As shown, part of the thermal radiation within the battery band gap V is transmitted, and the thermal radiation outside the battery band gap V is reflected;

[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 regulation of the thermal radiation spectrum.

[0081] The entire process of optimizing the regulation of the radiation spectrum by the thermal photovoltaic filter is as described above;

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

[0083] In detail, there are many options for the structure of the entire filter, each of which can reflect the efficient regulation of thermal radiation within a certain range. The simplest model is a three-layer induced transmission filter, that is, it only includes a substrate 101, a dielectric layer 103 and two parts of the dielectric layer. In this case, the number of layers of the induced transmission filter is only 3, such as Figure 1 As shown;

[0084] In detail, when the metal layer 102 in the three-layer induced transmission filter is not considered, the dielectric layer 103 consists of a first part 103a and a second part 103b, and 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 of about 1.2μm in the band gap is selected, and an ultra-thin silver layer is inserted at the point where the structural electric field distribution is minimum at the corresponding wavelength. At this time, the silver layer is located near the local minimum of the electric field in the dielectric layer in the 1-2.5μm band, so the impact on the electric field is minimal. The thermal radiation in this band is mainly transmitted by the stacked structure of the first part and the second part, forming induced transmission; while the thermal radiation in other bands has a larger electric field at Ag and is therefore significantly affected by the Ag layer, and the optical properties of Ag are mainly reflection, so the thermal radiation in other bands is mainly reflection. Ultimately, the filter can achieve high reflectivity for thermal radiation with a wavelength greater than the band gap wavelength and transmit thermal radiation with a wavelength less than the band gap wavelength, realizing efficient spectral regulation for thermal photovoltaic 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 spectrum of the structure. In order to take this influence into account, the thickness and insertion position of the nanoscale metal layer can be optimized based on the output model of the thermophotovoltaic cell with the thermophotovoltaic efficiency as the goal, thereby achieving efficient regulation of the thermal radiation spectrum and completing the design of the few-layer filter. When this three-layer filter structure is applied to the TPV system, combined with a 1400℃ black body and a GaSb cell, the relationship between its thermophotovoltaic efficiency and the position and thickness of the metal layer is as follows: Figure 2 shown.

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

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

[0089] Example 9

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

[0091] The substrate 101 is ZnS;

[0092] The metal layer 102 is 10 to 30 nm of Ag;

[0093] The first part 103a is 80 to 200 nm of ZnS;

[0094] The upper dielectric material U is 90-150nm ZnS;

[0095] The lower dielectric material D is 260-400nm MgF2;

[0096] In detail, when the metal layer 102 in the four-layer induced transmission filter is not considered, the substrate 101 and the dielectric layer 103 constitute a dielectric structure. The dielectric structure and the environment can form two resonant cavities composed of "air-zinc sulfide-magnesium fluoride" and "zinc sulfide-magnesium fluoride-substrate", which can form FP modes at different wavelengths and are distributed in the zinc sulfide and magnesium fluoride layers respectively, and form several transmission peaks. At the same time, when the wavelengths of the modes distributed in the two layers are similar, modal splitting will occur, and the two modes will shift in the direction away from each other's wavelength. Based on the induced transmission principle, the transmission peak with a wavelength of about 1μm in the band gap is selected, and an ultra-thin silver layer is inserted at the minimum distribution of the structural electric field at the corresponding wavelength. Similarly to the three-layer filter structure, the silver layer has the least effect on the electric field in the 1-2.5μm band, showing transmission characteristics, and the thermal radiation in other bands has a larger electric field at Ag, showing reflection characteristics.

[0097] It should be noted that, in the structure of the four-layer induced transmission filter, the FP resonance modes can be localized in two layers of materials respectively, and 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 the positions when the modes exist alone in the direction away from each other, such as Figure 6 shown.

[0098] Figure 7The transmission, reflection and absorption spectra of the filter calculated based on the above scheme. For gallium antimonide cells, the band gap wavelength is 1.72 microns, and the filter shows a clear transmission peak at 0.7-1.72 microns. At the same time, it shows a reflectivity of more than 98% in the band with a wavelength greater than 1.72 microns, and the maximum absorption peak in the band of 0.5-10 microns is less than 4%. Therefore, when the filter is used in a thermal photovoltaic system, the filter will reflect more than 98% of the thermal radiation with a wavelength greater than 1.72 microns, that is, the thermal radiation that cannot be converted into electrical energy by the battery, to the thermal radiator to achieve energy recovery and improve the efficiency of the thermal photovoltaic system.

[0099] Specifically, the four-layer induced transmission filter is applied to the thermophotovoltaic system in combination with a 1400°C blackbody radiator and a GaSb cell, which can achieve an increase in the thermophotovoltaic efficiency from 8.8% to 24.0% compared to a system without a filter.

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

[0101] In detail, taking the 4-layer structure as an example, within the range of 0-60°, the directional spectral radiation force of the filter transmission will not significantly deviate from the designed spectrum, and the peak shift is only 132nm; when the angle is greater than 60°, since the blackbody emission thermal radiation follows the Lambert cosine law, the directional radiation force will decrease with the increase of the angle. Therefore, the influence of the directional spectral radiation force that blue-shifts with the increase of the angle will be weakened, causing the thermal radiation of the transmission filter to be mainly concentrated in the designed transmission band, such as Figure 8 shown.

[0102] Furthermore, due to the small number of layers and simple optical mechanism, the structure spectrum is less affected by the thickness processing error of each layer, so the structure has good processing robustness. Taking the 4-layer structure as an example, considering the thickness errors of the metal layer and the dielectric layer are ±15% and 5% respectively, the spectra of all combined structures are applied to the same thermophotovoltaic system, and their efficiency distribution is as follows: Figure 8 As shown, after the processed filter is combined with a 1400℃ blackbody radiator and a GaSb cell, there is a 50% probability of achieving an absolute drop in efficiency of no more than 0.12%, and a 90% probability of obtaining a thermophotovoltaic efficiency of more than 23.67%, as shown in Fig. 9 shown.

[0103] Example 10

[0104] Reference Figures 1 to 9 , which is the tenth embodiment of the present invention, and is based on the previous embodiment, and is different from the previous embodiment in that: a transmission peak wavelength λ1 close to and smaller than the battery band gap V is selected on the dielectric structure 100, and the other wavelength is λ2;

[0105] An ultra-thin metal 101 is inserted at the minimum electric field corresponding to the transmission peak wavelength λ1, and thermal radiation is induced to be transmitted on the dielectric structure 100;

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

[0107] Importantly, it should be noted that the construction and arrangement of the present application shown in a number of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible without substantially departing from the novel teachings and advantages of the subject matter described in the application (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, directional changes, etc.). For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of the execution function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

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

[0109] It should be understood that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but for those of ordinary skill having the benefit of this disclosure, the development effort will be a routine task of design, fabrication, and production without undue experimentation.

[0110] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A filter for thermophotovoltaics, characterized in that: include, A stacked structure (100), comprising 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).

2. A filter for thermophotovoltaics according to claim 1, characterized in that: The first part (103a) and the second part (103b) of the dielectric layer (103) are a layer of dielectric material or a structure in which dielectric materials with different refractive indices are alternately stacked, and the total number of material layers of the first part (103a) and the second part (103b) is 3 to 5.

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

4. A filter for thermophotovoltaics according to claim 3, characterized in that: The metal layer (102) is a metal material with a thickness of 10 nm to 40 nm, and the reflectivity of the metal layer (102) in the 2 to 10 μm band is greater than 90%.

5. A filter for thermophotovoltaics according to claim 4, characterized in that: The maximum absorption rate of the first part (103a) in the 0.6-8 μm band is less than 2%.

6. A filter for thermophotovoltaics according to claim 5, characterized in that: The contact surface between the substrate (101) and the dielectric layer (103) is parallel to the contact surfaces of the remaining layers.

7. A filter for thermophotovoltaics according to claim 6, characterized in that: The substrate (101) is a GaSb battery substrate; The first part (103a) and the second part (103b) are both composed of ZnS; The metal layer (102) is Ag.

8. The filter for thermophotovoltaics according to claim 7, characterized in that: The thickness of the metal layer (102) is 10 to 30 nm; The first portion (103a) has a thickness of 130 to 160 nm; The thickness of the second portion (103b) is 260-400 nm.

9. A method for designing a filter for thermophotovoltaics, characterized in that: A filter for thermophotovoltaics according to claims 1 to 8, and stacking dielectric materials on the substrate (101) to construct a plurality of Fabry-Perot (FP) resonance modes; Based on induced transmission, a metal layer (102) is inserted at the minimum electric field of the designed wavelength in the stacked dielectric material to transmit part of the thermal radiation within the battery band gap V and reflect the thermal radiation outside the battery band gap 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 regulation of the thermal radiation spectrum.

10. The method for designing a filter for thermophotovoltaic according to claim 9, characterized in that: Selecting a transmission peak wavelength λ1 close to and smaller than the battery band gap V on the dielectric structure, and the other wavelength range is λ2; Inserting an ultra-thin metal (101) at the minimum electric field corresponding to the transmission peak wavelength λ1, so that thermal radiation is induced to be transmitted in the stacked structure (100); In the wavelength range λ2, thermal radiation is reflected in the stack structure (100).

11. The method for designing a filter for thermophotovoltaic according to claim 10, characterized in that: When the stacked structure (100) has four layers, that is, the second part (103b) is composed of two layers of dielectric material: The substrate (101) is ZnS; The metal layer (102) is 10 to 30 nm of Ag; The first part (103a) is 80-200nm ZnS; The upper dielectric material (U) is 90-150nm ZnS; The lower dielectric material (D) is 260-400nm MgF2; The four-layer stacked structure (100) is combined with a 1400°C black body radiator and a GaSb cell, and the thermophotovoltaic efficiency is 24.0%; When the incident angle is between 0° and 60°, the directional spectral radiation force transmitted by the stacked structure (100) is offset and the designed spectral amplitude is reduced; When considering that 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 decrease in efficiency of no more than 0.12%, and a 90% probability of obtaining a thermophotovoltaic efficiency of more than 23.67%.

Images