Manufacturing methods of thermoelectric elements, power generation devices, electronic devices and thermoelectric elements

Abstract

[Problem] To provide a thermoelectric element, a power generation device, an electronic device, and a method for manufacturing a thermoelectric element that can achieve stable power generation efficiency. [Solution] A thermoelectric element (1) that does not require a temperature difference between electrodes comprises: a first electrode (11); a second electrode (12) disposed spaced apart from the first electrode (11); a donor layer (21) comprising at least one layer disposed between the first electrode (11) and the second electrode (12); and an acceptor layer (22) comprising at least one layer disposed between the donor layer (21) and the second electrode (12), wherein at least one of the donor layer (21) and the acceptor layer (22) comprises an organic material representing orientation polarization.

Description

[Technical Field]

[0001] This invention relates to thermoelectric elements, power generation devices, electronic devices, and methods for manufacturing thermoelectric elements that do not require temperature differences between electrodes. [Previous Technology]

[0002] In recent years, the development of thermoelectric elements that generate electrical energy from heat has become increasingly popular. In particular, thermoelectric elements that do not require a temperature difference are proposed, such as the thermoelectric element disclosed in Patent Document 1. Such thermoelectric elements are expected to be used for various purposes compared to those that generate electrical energy by utilizing the temperature difference supplied to the electrodes.

[0003] Patent Document 1 discloses a thermoelectric conversion element having a first electrode layer and a second electrode layer arranged separately from each other, and a thermoelectric conversion layer in contact with the first electrode layer and the second electrode layer. Furthermore, the thermoelectric conversion layer is composed of a thermoelectric conversion material containing a conductive material coated with a non-conductive material and a dispersion medium, wherein the resistivity of the conductive material is 1×10¹ to 1×10⁹ Ω·m. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-212823 [Summary of the Invention]

[0005] [The problem the invention aims to solve]

[0006] Here, as in Patent Document 1, in thermoelectric elements using thermoelectric conversion materials having a coating conductive material and a dispersion medium, deviations occur in the dispersion state of the coating conductive material, and the movement of electrons may be locally suppressed. Therefore, there is a concern that stable power generation efficiency cannot be obtained.

[0007] Therefore, the present invention was created in view of the above-mentioned problems, and its object is to provide thermoelectric elements, power generation devices, electronic devices, and methods for manufacturing thermoelectric elements that can achieve stable power generation efficiency. [Means for solving the problems]

[0008] The thermoelectric element according to the first invention is a thermoelectric element that does not require a temperature difference between electrodes, characterized in that it comprises: a first electrode; a second electrode, which is disposed spaced apart from the first electrode; a donor layer comprising at least one layer, which is disposed between the first electrode and the second electrode; and an acceptor layer comprising at least one layer, which is disposed between the donor layer and the second electrode, wherein at least one of the donor layer and the acceptor layer comprises an organic material representing orientation polarization.

[0009] The thermoelectric element involved in the second invention is characterized in the first invention by having a work function of the first electrode that is higher than that of the second electrode.

[0010] The thermoelectric element involved in the third invention is characterized in the second invention by having the donor layer and the acceptor layer as solids.

[0011] The thermoelectric element involved in the fourth invention is characterized in that the LUMO (Lowest Unoccupied Molecular Orbital) of the acceptor layer is between the HOMO (Highest Occupied Molecular Orbital) and the LUMO of the donor layer, and the HOMO of the acceptor layer is higher than the HOMO of the donor layer.

[0012] The thermoelectric element of the fifth invention is one of the first to fourth inventions, wherein the acceptor layer comprises a first acceptor layer in contact with the donor layer, a second acceptor layer disposed between the first acceptor layer and the second electrode, and an electron transport layer disposed between the second acceptor layer and the second electrode, wherein at least one of the first acceptor layer, the second acceptor layer and the electron transport layer comprises an organic material representing orientation polarization as a feature.

[0013] The thermoelectric element involved in the sixth invention is characterized in that the acceptor layer includes a hybrid layer that is in contact with the donor layer, thereby mixing the two types of materials.

[0014] The thermoelectric device according to the seventh invention is characterized by having a thermoelectric element as described in the first invention, a first wiring electrically connected to the first electrode, and a second wiring electrically connected to the second electrode.

[0015] The electronic machine according to the eighth invention is characterized by having the thermoelectric element described in claim 1 and an electronic component that uses the thermoelectric element in a power source and drives it.

[0016] The manufacturing method of the thermoelectric element according to the ninth invention is a manufacturing method of a thermoelectric element that does not require a temperature difference between electrodes, characterized by comprising: a first electrode forming process, which forms a first electrode; a donor layer forming process, which forms a donor layer comprising at least one layer; a acceptor layer forming process, which forms an acceptor layer comprising at least one layer; and a second electrode forming process, which forms a second electrode, wherein at least one of the donor layer and the acceptor layer comprises an organic material representing orientation polarization.

[0017] The manufacturing method of the thermoelectric element according to the 10th invention is based on the 9th invention, wherein the donor layer forming process forms the donor layer on the surface of the first electrode, the acceptor layer forming process forms the acceptor layer on the surface of the donor layer, and the second electrode forming process forms the second electrode on the surface of the acceptor layer under reduced pressure. The work function of the first electrode is higher than that of the second electrode as a feature.

[0018] The method for manufacturing the thermoelectric element according to the 11th invention is based on the 9th or 10th invention, wherein the acceptor layer forming process includes: forming a first acceptor layer on the surface of the donor layer; forming a second acceptor layer on the surface of the first acceptor layer; and forming an electron transport layer on the surface of the second acceptor layer. The second electrode forming process includes forming the second electrode on the surface of the electron transport layer. At least one of the first acceptor layer, the second acceptor layer, and the electron transport layer is characterized by containing an organic material representing orientation polarization. [Effects of the Invention]

[0019] In the first to sixth inventions, at least one of the donor layer and the acceptor layer contains an organic material representing orientation polarization. A potential difference arises along the stacking direction of each electrode in the layer containing the orientation polarized organic material. Therefore, at the interface between the donor and acceptor layers, when a charge-transfer complex is formed by thermal excitation of electrons, charge transfer can be promoted through the layer containing the orientation polarized organic material. In this way, the power generation efficiency can be stabilized.

[0020] In particular, if the work function of the first electrode is higher than that of the second electrode in the second invention, an electric field can be formed between the electrodes based on the difference in the amount of hot electrons generated from each electrode. This further promotes charge transfer between the electrodes.

[0021] In particular, when the third invention is used, the donor layer and the acceptor layer are solid. Therefore, there is no need to provide support parts or the like to maintain the distance (gap) between the electrodes with different work functions, and the deviation of the gap caused by the forming accuracy of the support parts can be eliminated. In this way, it is possible to achieve more stable power generation efficiency.

[0022] In particular, when the fourth invention is used, the LUMO of the acceptor layer is between the HOMO and LUMO of the donor layer, and the HOMO of the acceptor layer is higher than that of the donor layer. Therefore, at the interface between the donor layer and the acceptor layer, a charge separation state caused by thermal excitation can be easily formed. In this way, the stabilization of power generation efficiency can be easily achieved.

[0023] In particular, when the fifth invention is used, the acceptor layer includes a first acceptor layer, a second acceptor layer, and an electron transport layer. Therefore, electrons generated at the interface between the donor layer and the acceptor layer can move smoothly toward the second electrode. Accordingly, the decrease in power generation efficiency can be suppressed.

[0024] In particular, if the power generation device is equipped with the thermoelectric element in the first invention, then a power generation device that aims to stabilize power generation efficiency can be realized.

[0025] In particular, if the electronic device is equipped with the thermoelectric element of the first invention by means of the eighth invention, then a power generation device that seeks to stabilize power generation efficiency can be realized.

[0026] In the 9th to 11th inventions, at least one of the donor layer and the acceptor layer contains an organic material representing orientation polarization. A potential difference arises along the stacking direction of the electrodes in the layer containing the orientation polarized organic material. Therefore, at the interface between the donor and acceptor layers, when a charge separation state is formed by thermal excitation, charge transfer can be promoted through the layer containing the orientation polarized organic material. In this way, the power generation efficiency can be stabilized.

[0027] In particular, when the second electrode is formed in accordance with the tenth invention, it is formed on the surface of the acceptor layer under reduced pressure. Therefore, the variation of the work function of the second electrode can be suppressed. Accordingly, it is possible to achieve greater stability in power generation efficiency.

Implementation Method

[0029] Hereinafter, an example of a thermoelectric element, power generation device, electronic device, power generation method, and thermoelectric element manufacturing method according to an embodiment of the present invention will be described with reference to the drawings. Furthermore, in each drawing, the height direction of each electrode in the stack is designated as the first direction Z, a plane direction intersecting the first direction Z (e.g., orthogonal) is designated as the second direction X, and another plane direction intersecting both the first direction Z and the second direction X (e.g., orthogonal) is designated as the third direction Y. Moreover, the configurations in each drawing are shown schematically for illustrative purposes; differences may exist even if they differ from the drawings, such as the size of each configuration or the size comparison within each configuration.

[0030] (First embodiment: thermoelectric element 1, power generation device 100) FIG1 is a schematic cross-sectional view showing an example of thermoelectric element 1 and power generation device 100 in this embodiment.

[0031] As shown in FIG1(a), the power generation device 100 includes a thermoelectric element 1, a first wiring 101, and a second wiring 102. The thermoelectric element 1 converts heat energy into electrical energy. The power generation device 100, which includes such a thermoelectric element 1, is mounted or installed on, for example, a heat source (not shown), and outputs the electrical energy generated by the thermoelectric element 1 to a load R via the first wiring 101 and the second wiring 102, based on the heat energy of the heat source. One end of the load R is electrically connected to the first wiring 101, and the other end is electrically connected to the second wiring 102. The load R represents, for example, an electrical machine. The load R drives, for example, the power generation device 100, using either a main power source or an auxiliary power source.

[0032] Examples of heat sources for the thermoelectric element 1 include electronic devices such as CPUs (Central Processing Units), electronic components, light-emitting elements such as LEDs (Light Emitting Diodes), automobile engines, factory production equipment, the human body, sunlight, and ambient temperature. For example, electronic devices, electronic components, light-emitting elements, engines, and production equipment are artificial heat sources. The human body, sunlight, and ambient temperature are natural heat sources. The power generation device 100 equipped with the thermoelectric element 1 can be installed inside mobile machines such as IoT (Internet of Things) devices, wearable devices, and self-contained sensor terminals, as a replacement or auxiliary for batteries. Moreover, the power generation device 100 can also be applied to larger devices such as solar power generation.

[0033] The thermoelectric element 1 converts heat energy emitted by, for example, an artificial heat source or heat energy held by a natural heat source into electrical energy to generate an electric current. The thermoelectric element 1 can be installed not only within the power generation device 100, but also inside the mobile device or the self-contained sensor terminal. In this case, the thermoelectric element 1 can serve as a replacement or auxiliary component for the battery of the mobile device or the self-contained sensor terminal.

[0034] The thermoelectric element 1, as shown in FIG1, includes a first electrode 11, a second electrode 12, a donor layer 21, and an acceptor layer 22. The thermoelectric element 1 may also include, for example, a substrate 51.

[0035] The first electrode 11 and the second electrode 12 are arranged facing each other. The donor layer 21 and the acceptor layer 22 are disposed between the first electrode 11 and the second electrode 12.

[0036] The donor layer 21, as shown in FIG2(a), has HOMO (Highest Occupied Molecular Orbital) 21H and LUMO (Lowest Unoccupied Molecular Orbital) 21L. The acceptor layer 22 has HOMO 22H and LUMO 22L that are different from those of the donor layer 21. For example, HOMO 21H represents a value higher than LUMO 22. In addition, if the donor layer 21 and the acceptor layer 22 comprise multiple layers, the layers adjacent to each other have the aforementioned HOMO 21H, 22H, and LUMO 21L, 22L.

[0037] When thermoelectric element 1 is supplied with thermal energy, as shown in, for example, FIG2(b), electrons in HOMO21H migrate to LUMO22L in the adjacent acceptor layer 22, generating holes in HOMO21H (function A in FIG2(b)). Thus, a charge transfer complex (CT) is formed. Furthermore, the holes move to the first electrode 11 via the donor layer 21, and the electrons move to the second electrode 12 via the acceptor layer 22, thereby enabling the thermoelectric element 1 to generate electricity.

[0038] Here, the thermal energy used for power generation that does not require a temperature difference between electrodes is weaker than the thermal energy used for power generation that requires a temperature difference, or the light energy used for power generation such as solar power. Therefore, there is a risk that the charge transfer formed by the migration of electrons may not reach each electrode 11, 12, which the inventors have identified as a major cause of unstable power generation efficiency.

[0039] In this embodiment, at least one of the donor layer 21 and the acceptor layer 22 in the thermoelectric element 1 contains an organic material representing orientation polarization. In this case, a potential difference occurs in the layer containing the organic material representing orientation polarization along the stacking direction (first direction Z) of each electrode 11, 12. Therefore, at the interface between the donor layer 21 and the acceptor layer 22, when a charge-transfer complex is formed by thermal excitation of electrons, charge transfer can be promoted through the layer containing the organic material representing orientation polarization (effect B in FIG. 2(b)). In this way, the power generation efficiency can be stabilized.

[0040] Furthermore, when a layer containing an organic compound representing orientation polarization is formed, for example, it exhibits spontaneous orientation polarization (spontaneous polarization) and has the characteristic of maintaining surface potential. Materials used as organic compounds representing orientation polarization include, for example, copper phthalocyanine (CuPc), BCP (Bathocuproine), and fluorinated copper phthalocyanine (F16CuPc). In addition to the above, materials used include, for example, 4,4'-bis[N-(naphthyl)-N-phenyl-amino]biphenyl (α-NPD), 2,2',2''-(1,3,5-benzyl alcohol)-tris(1-phenyl-1-H-benzimidazole) (TPBi), bis(2-methyl-8-hydroxyquinoline) (p-hydroxy)aluminum (BAlq), 1,3-bis[(4-t-tert-butylphenyl)-1,3,4-oxadiazole]phenylene (OXD-7), and tris(8-hydroxyquinoline)aluminum (Alq3). Tris(2-phenylpyridine)iridium(III) (Ir(ppy)3), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-N3,N3,N6,N6-tetraphenyl-9H-carbazole-3,6,diamine (DACT-II), bis[2-(2-pyridyl-N)phenyl-C](2,4-pentanedione-O2,O4)iridium(III) (Ir(ppy)2(acac)), (4s,6s)-2,4,5,6-tetra(9 H-Carbazole-9-yl)isophthalonitrile (4CzIPN), 1,3-bis[2-(2,2'-bipyridin-6-yl)-1,3,4-oxadiazol-5-yl]benzene (Bpy-OXD), 4,6-bis(3,5-di(pyridin-3-yl)phenyl)-2-methylpyrimidine (B3PyMPM), 4,5-di(9H-carbazole-9-yl)phthalonitrile (2CzPN), 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyl) Materials such as tris(7-propyl-8-hydroxyquinoline)aluminum (Al(7-prq)3), tris(5-chloro-8-hydroxyquinoline)aluminum (Al(q-Cl)3), tris(8-hydroxyquinoline)-gallium (Gaq3), bis(8-hydroxyquinoline)zinc (Znq2), and 3,4,5,6-tetra-9H-carbazole-9-yl-1,2-phenylenedione (4CzPN) can be used depending on the application.

[0041] Even if the layer containing the organic material representing orientation polarization contains only one type of material, for example, it is possible to maintain the surface potential characteristic of the material more easily than in the case of materials that disperse, for example, particles.

[0042] The following is a detailed explanation of each component.

[0043] <First Electrode 11, Second Electrode 12> The first electrode 11 and the second electrode 12 are disposed at intervals along, for example, a first direction Z. The first electrode 11 is configured to be in contact with, for example, a substrate 51.

[0044] Even if the first electrode 11 and the second electrode 12 are configured to be connected to, for example, the same substrate 51. In this case, the first electrode 11 and the second electrode 12 are configured to be spaced apart along the second direction X or the third direction Y.

[0045] Even if each electrode 11, 12 extends in, for example, the second direction X and the third direction Y, a plurality of electrodes may be provided. For example, even if a second electrode 12 is provided facing each other at a different position from each of the plurality of first electrodes 11. Furthermore, even if a first electrode 11 is provided facing each other at a different position from each of the plurality of second electrodes 12.

[0046] The thickness of the first electrode 11 and the second electrode 12 is, for example, more than 1 nm and less than 1 μm. The thickness of the first electrode 11 and the second electrode 12 is, for example, more than 1 nm and less than 50 nm.

[0047] Even if the first electrode 11 and the second electrode 12 have different work functions, for example, the work function of the first electrode 11 is higher than that of the second electrode 12. In this case, an electric field can be formed between the electrodes based on the difference in the amount of thermionic electrons generated from each electrode 11, 12. In this way, charge transfer between the electrodes can be further promoted. In this way, it is possible to achieve a more stable power generation efficiency.

[0048] Furthermore, the "work function" represents the minimum energy required to extract an electron from a solid in a vacuum, representing the difference between the vacuum level and the Fermi level. In each embodiment, the work function is explained with the lower side being higher than the upper side in the electronic states shown in Figure 2(a). For example, a material with a lower work function than a material with a higher work function indicates a tendency for electrons to escape more easily. In addition to the Kelvin method, the work function can also be measured using well-known methods such as ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), or Auger electron spectroscopy (AES).

[0049] Furthermore, even in "HOMO" and "LOMO", which are the same as the work function, the lower side of the electronic states shown in Figure 2(a) is higher than the upper side. Furthermore, HOMO and LUMO can be measured using well-known measurement methods. For example, in addition to the aforementioned spectroscopic methods, HOMO can be measured using well-known methods such as photoemission yield spectroscopy (PYS). Furthermore, LUMO can be calculated, for example, using measurement or absorption spectra using inverse photoelectron spectroscopy (IPES).

[0050] In addition, the "work function", "HOMO" and "LOMO" shown in this description can be either measured values ​​for each component of the thermoelectric element 1 or well-known values ​​measured for materials.

[0051] The materials used for the first electrode 11 and the second electrode 12 are conductive materials. For example, the same material can be used for both the first electrode 11 and the second electrode 12, and in this case, different work functions are acceptable.

[0052] As for the materials of each electrode 11 and 12, in addition to materials composed of a single element such as iron, aluminum, or copper, alloys composed of two or more elements may also be used. As for the materials of each electrode 11 and 12, non-metallic conductive materials may also be used. Examples of non-metallic conductive materials include carbon-based materials such as silicon (Si: for example, p-type Si or n-type Si) and graphite.

[0053] In particular, well-known conductive materials that do not transmit light can be used as the materials for each electrode 11 and 12. Therefore, power generation caused by light penetrating each electrode 11 and 12 can be prevented. Accordingly, deviations in power generation caused by factors other than heat can be suppressed. In addition, the term "light" refers to light in the wavelength range used, for example, in solar power generation, and specifically to light in the wavelength range of, for example, 200 nm to 800 nm.

[0054] <Donor layer 21, acceptor layer 22> The donor layer 21 and acceptor layer 22 are sandwiched between each of the electrodes 11 and 12 and are configured to be connected to each other. The donor layer 21 and acceptor layer 22 comprise at least one layer. The donor layer 21 is connected to the first electrode 11 and spaced apart from the second electrode 12. The acceptor layer 22 is connected to the second electrode 12 and spaced apart from the first electrode 11. That is, the above-mentioned components 11, 12, 21, and 22 are stacked in the order of the first electrode 11, the donor layer 21, the acceptor layer 22, and the second electrode 12.

[0055] The donor layer 21 and the acceptor layer 22 are the same as, for example, each of the electrodes 11 and 12, extending in the second direction X and the third direction Y. The shape of the donor layer 21 and the acceptor layer 22 is the same as, for example, each of the electrodes 11 and 12.

[0056] The thickness of the donor layer 21 and the acceptor layer 22 is, for example, more than 1 nm and less than 1 μm. The thickness of the donor layer 21 and the acceptor layer 22 is, for example, more than 1 nm and less than 50 nm.

[0057] The donor layer 21 and acceptor layer 22 are formed of solid. Therefore, there is no need to provide support parts or the like to maintain the distance (gap) between the electrodes 11 and 12. In the case of using electrodes 11 and 12 with different work functions, columnar or frame-shaped support parts are sometimes formed, and the gaps are filled with solvents or the like. In this case, with the deviation in the formation of the support parts, the deviation in the gap between the opposing surfaces of the electrodes 11 and 12 will occur, resulting in a decrease in power generation efficiency. In this case, by providing the donor layer 21 and acceptor layer 22 formed of solid within the gap, the deviation in the gap between the opposing surfaces of the electrodes 11 and 12 can be eliminated. In this way, the power generation efficiency can be further stabilized.

[0058] As the donor layer 21, a material suitable for moving holes to the first electrode 11 is used. As the donor layer 21, a material containing an organic substance representing the above-mentioned orientation polarization is used, and α-NPD or mCP is particularly preferred on the surface in contact with the acceptor layer 22.

[0059] As the donor layer 21, in addition to the above-mentioned materials containing organic compounds representing orientation polarization, organic materials such as N,N'-diphenyl-N,N'-(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD), 9-[3,5-bis(2-dibenzothiophene)phenyl]-9H-carbazole (Tris-PCz), pentacene, 4,4',4''-tris[(3-methylphenyl)phenylamino]triphenylamine (m-MTDATA), 2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine (T2T), 1,1-bis[(di-4-triamino)phenyl]cyclohexane (TAPC), 2,2',7,7'-tetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (Spiro-OMeTAD) are used. As the donor layer 21, in addition to p-type semiconductors such as ITO, ZnO, and Zn-Si-O, materials containing doped materials such as MoOx, V2O5, and WO3 can also be used.

[0060] As the acceptor layer 22, a material suitable for moving electrons to the second electrode 12 is used. As the acceptor layer 22, the aforementioned material containing an organic compound representing orientation polarization is used, and in particular, TPBi, OXD-7, Alq3, Al(7-prq)3, Gaq3, BCP, Bpy-OXD, or B3PyMPM are preferred on the surface in contact with the donor layer 21.

[0061] As the acceptor layer 22, in addition to materials containing organic compounds representing the aforementioned orientation polarization, organic materials such as 3,4,9,10-perylenetetracarboxylic acid benzimidazole (PTCBI), C60, C70, phenanthroline (BPhen), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzobenzene (HAT-CN), and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinone dimethylane (F4TCNQ) can be used. As the acceptor layer 22, in addition to using n-type semiconductors such as CuSnI, materials containing doped materials such as Cs2CO3, Li, Mg, and Ca can also be used.

[0062] For example, the LUMO22L of the acceptor layer 22 is between the HOMO21H and LUMO21L of the donor layer 21, and the HOMO22H of the acceptor layer 22 is higher than the HOMO21H of the donor layer 21. In this case, at the interface between the donor layer 21 and the acceptor layer 22, the formation of a charge-transfer complex caused by thermal excitation of electrons can be promoted.

[0063] For example, the work function of the first electrode 11 is between HOMO21H and LUMO21L of the donor layer 21, while the work function of the second electrode 12 is lower than that of LUMO22L of the acceptor layer 22. In this case, energy barriers between the components that hinder charge transfer can be reduced. That is, it promotes the movement of holes toward the first electrode 11 while simultaneously promoting the movement of electrons toward the second electrode 12. In this way, it is possible to improve power generation efficiency.

[0064] For example, the acceptor layer 22 may include a hybrid layer. A hybrid layer refers to a layer formed by mixing two types of materials in contact with the donor layer 21. In this case, for example, the acceptor layer 22 may include a transport layer disposed between the hybrid layer and the second electrode 12.

[0065] Two types of materials are used in the hybrid layer: a material used in, for example, the donor layer 21, and a material used in the transport layer. In this case, portions corresponding to the aforementioned HOMO 21H, 22H and LUMO 21L, 22L can be formed within the hybrid layer. Therefore, the range of charge transfer complexes that can be formed can be expanded, and an improvement in power generation efficiency can be sought.

[0066] <Substrate 51> Substrate 51 is connected to, for example, the first electrode 11 and spaced apart from the second electrode 12, the donor layer 21 and the acceptor layer 22. Substrate 51 fixes the first electrode 11. Substrate 51 may include, for example, a first substrate 51a and a second substrate 51b. In this case, for example as shown in FIG1(b), the first substrate 51a is connected to the first electrode 11 and the second substrate 51b is connected to the second electrode 12.

[0067] The thickness of the substrate 51 is, for example, more than 1 μm and less than 10 mm, and can be arbitrary if the first electrode 11 can be fixed.

[0068] As the substrate 51, a plate-shaped material having, for example, insulating properties can be used, and well-known materials such as silicon, quartz, and pyrex (registered trademark) can be used. The substrate 51 can also be made of, for example, a thin film material, and well-known thin film materials such as PET (polyethylene terephthalate), PC (polycarbonate), and polyimide can also be used.

[0069] As the substrate 51, a conductive material can be used, such as iron, aluminum, copper, or an alloy of aluminum and copper. Furthermore, as the substrate 51, in addition to conductive semiconductors such as Si and GaN, a conductive polymer or similar material can also be used. When a conductive material is used for the substrate 51, wiring for connecting to the first electrode 11 is not required.

[0070] In particular, the substrate 51 can be made of a well-known insulating material that does not transmit light, or a well-known conductive material. Therefore, power generation caused by light penetrating the substrate 51 can be prevented. Accordingly, deviations in power generation caused by factors other than heat can be suppressed.

[0071] (First Embodiment: Method for Manufacturing Thermoelectric Element 1) Next, an example of a method for manufacturing thermoelectric element 1 in this embodiment will be described. Figure 3 is a flowchart showing an example of a method for manufacturing thermoelectric element 1 in this embodiment.

[0072] The manufacturing method of thermoelectric element 1 includes a first electrode forming process S110, a donor layer forming process S120, an acceptor layer forming process S130, and a second electrode forming process S140.

[0073] <First Electrode Formation Process S110> The first electrode formation process S110 forms the first electrode 11. In the first electrode formation process S110, the first electrode 11 is formed on a substrate 51, for example, as shown in FIG. 1(a). At this time, the first electrode 11 is formed after, for example, cleaning and baking the substrate 51. The first electrode 11 is formed by sputtering or vacuum evaporation under a reduced pressure environment, for example.

[0074] <Donor Layer Formation Process S120> The donor layer formation process S120 involves forming a donor layer 21 comprising at least one layer on the surface of the first electrode 11. The donor layer 21 comprises a layer formed, for example, using an organic material indicating orientation polarization. The donor layer 21 is formed, for example, by sputtering or vacuum evaporation under reduced pressure.

[0075] <Acceptor Layer Formation Process S130> The acceptor layer formation process S130 involves forming an acceptor layer 22 comprising at least one layer on the surface of the donor layer 21. The acceptor layer 22 comprises a layer formed, for example, using an organic material representing orientation polarization. The acceptor layer 22 is formed, for example, under reduced pressure by sputtering or vacuum evaporation.

[0076] <Second Electrode Formation Process S140> The second electrode formation process S140 involves forming a second electrode 12 on the surface of the acceptor layer 22. The second electrode 12 is formed using a material having, for example, a lower work function than the first electrode 11. The second electrode 12 is formed, for example, under reduced pressure by sputtering or vacuum evaporation.

[0077] By implementing the above-described engineering works, the thermoelectric element 1 in this embodiment is formed. In addition, by forming, for example, the wiring 101, 102, etc. shown in FIG1(a), the power generation device 100 in this embodiment is formed.

[0078] In addition, although the above describes the case in which the first electrode forming process S110, the donor layer forming process S120, the acceptor layer forming process S130 and the second electrode forming process S140 are performed in the order of, for example, the second electrode forming process S140, the acceptor layer forming process S130, the donor layer forming process S120 and the first electrode forming process S110.

[0079] In this case, in the second electrode formation process S140, a second electrode 12 is formed on, for example, the substrate 51. Then, in the acceptor layer formation process S130, an acceptor layer 22 is formed on, for example, the surface of the second electrode 12. Then, in the donor layer formation process S120, a donor layer 21 is formed on, for example, the surface of the acceptor layer 22. Then, in the first electrode formation process S110, a first electrode 11 is formed on the surface of the donor layer 21.

[0080] (First Embodiment: Modification of Thermoelectric Element 1) Next, a modification of the thermoelectric element 1 in this embodiment will be described. The difference between the above embodiment and the modification is that the acceptor layer 22 includes two or more layers. Furthermore, details identical to those described above will be omitted.

[0081] The acceptor layer 22 may include, for example, a first acceptor layer 22a and a second acceptor layer 22b, as shown in FIG. 4(a), or may include, for example, an electron transport layer 22c. At least any one of the first acceptor layer 22a, the second acceptor layer 22b, and the electron transport layer 22c contains an organic material representing orientation polarization. In this case, electrons generated at the interface between the donor layer 21 and the acceptor layer 22 can move smoothly toward the second electrode 12.

[0082] The first acceptor layer 22a is connected to the donor layer 21. The second acceptor layer 22b is disposed between the first acceptor layer 22a and the second electrode 12. The electron transport layer 22c is disposed between the second acceptor layer 22b and the second electrode 12.

[0083] The LUMO 22L of the first acceptor layer 22a is higher than, for example, the LUMO of the second acceptor layer 22b. In this case, after the formation of the charge-transfer complex, electrons migrate from the first acceptor layer 22a to the second acceptor layer 22b by utilizing thermal energy, thereby increasing the energy of the electrons. Accordingly, it is possible to increase the output voltage. In particular, by including an organic material representing orientation polarization in the first acceptor layer 22a, it is possible to promote the movement of electrons in the acceptor layer 22 and increase the energy of the electrons.

[0084] In addition to the above, for example, the LUMO of the second acceptor layer 22b is higher than that of the electron transport layer 22c, which can further promote electron movement. Furthermore, by including organic materials representing orientation polarization in the donor layer 21, the first acceptor layer 22a and the electron transport layer 22c, the increase in output voltage and the decrease in power generation efficiency can be suppressed.

[0085] Additionally, as shown in FIG4(b), the donor layer 21 may include a first donor layer 21a and a second acceptor layer 21b, or it may include, for example, a hole transport layer 21c. At least any one of the first acceptor layer 21a, the second acceptor layer 21b, and the hole transport layer 21c may contain an organic material representing orientation polarization. Even in this case, holes occurring at the interface between the donor layer 21 and the acceptor layer 22 can be smoothly moved toward the first electrode 11.

[0086] (First Embodiment: Modification of the Manufacturing Method of Thermoelectric Element 1) Next, a modification of the manufacturing method of thermoelectric element 1 in this embodiment will be described.

[0087] In this modified example, the acceptor layer formation process S130 includes the process of forming the first acceptor layer 22a and the second acceptor layer 22b, and may also include the process of forming, for example, an electron transport layer 22c. The first acceptor layer 22a is formed on the surface of the donor layer 21. The second acceptor layer 22b is formed on the surface of the first acceptor layer 22a. The electron transport layer 22c is formed on the surface of the second acceptor layer 22b. Furthermore, the second electrode formation process S140 includes forming a second electrode 12 on the surface of the electron transport layer 22c. In this case, as described above, it is possible to promote the movement of electrons in the acceptor layer 22 and increase the energy of the electrons.

[0088] In this embodiment, at least one of the donor layer 21 and the acceptor layer 22 contains an organic material representing orientation polarization. A potential difference arises along the stacking direction (e.g., the first direction Z) of each electrode 11, 12 in the layer containing the orientation polarized organic material. Therefore, at the interface between the donor layer 21 and the acceptor layer 22, when a charge-transfer complex is formed by thermal excitation of electrons, charge transfer can be promoted through the layer containing the orientation polarized organic material. In this way, the power generation efficiency can be stabilized.

[0089] Furthermore, in this embodiment, the work function of the first electrode 11 is higher than that of the second electrode 12. Therefore, an electric field can be formed between the electrodes based on the difference in the amount of hot electrons generated from each electrode 11, 12. In this way, charge transfer between the electrodes can be further promoted.

[0090] Furthermore, in this embodiment, the donor layer 21 and the acceptor layer 22 are solid. Therefore, there is no need to provide supports or other means to maintain the distance (gap) between the electrodes 11 and 12 that have a work function difference, and the deviation in gap caused by the forming accuracy of the supports can be eliminated. In this way, it is possible to achieve more stable power generation efficiency.

[0091] Furthermore, in this embodiment, the LUMO 22L of the acceptor layer 22 is between the HOMO 21H and LUMO 21L of the donor layer 21, and the HOMO 22H of the acceptor layer 22 is higher than that of the donor layer 21. Therefore, a charge separation state caused by thermal excitation can be easily formed at the interface between the donor layer 21 and the acceptor layer 22. In this way, the power generation efficiency can be easily stabilized.

[0092] Furthermore, in this embodiment, the acceptor layer 22 includes a first acceptor layer 22a, a second acceptor layer 22b, and an electron transport layer 22c. Therefore, electrons generated at the interface between the donor layer 21 and the acceptor layer 22 can move smoothly toward the second electrode 12. In this way, the decrease in power generation efficiency can be suppressed.

[0093] Furthermore, in this embodiment, the second electrode formation process S140 is formed on the surface of the acceptor layer 22 under reduced pressure. Therefore, fluctuations in the work function of the second electrode 12 can be suppressed. Accordingly, more stable power generation efficiency can be achieved.

[0094] (Second Embodiment: Thermoelectric Element 1) Next, an example of the thermoelectric element 1 in the second embodiment will be described. The difference between the above embodiment and the second embodiment is that it has a shielding portion 61. In addition, the description of contents that are the same as those described above will be omitted.

[0095] The shielding portion 61 is provided on the side of the stacked donor layer 21 and acceptor layer 22, as shown in FIG5. The shielding portion 61 surrounds, for example, the donor layer 21 and the acceptor layer 22, and may be divided into, for example, two or more portions.

[0096] The shielding part 61 is made of an insulating material, such as a well-known insulating resin, like a fluorine-based insulating resin. By providing the shielding part 61, the durability of the thermoelectric element 1 can be improved.

[0097] Furthermore, a well-known insulating material that does not transmit light can be used as the material for the shielding portion 61. Therefore, power generation caused by light incident from the side of the thermoelectric element 1 can be prevented. In this way, deviations in power generation caused by factors other than heat can be suppressed. In particular, the shielding portion 61 can enhance the light shielding effect by being configured to be in contact with each of the electrodes 11, 12.

[0098] (Third Embodiment: Electronic Machine 500) <Electronic Machine 500> The above-mentioned thermoelectric element 1 and power generation device 100 can be mounted on, for example, an electronic machine. Hereinafter, several embodiments of the electronic machine will be described.

[0099] Figures 6(a) to 6(d) are schematic block diagrams showing examples of an electronic device 500 having a thermoelectric element 1. Figures 6(e) to 6(h) are schematic block diagrams showing examples of an electronic device 500 having a power generation device 100 including a thermoelectric element 1.

[0100] As shown in FIG6(a), the electronic machine 500 (electronic product) includes an electronic component 501 (electronic assembly), a main power supply 502, and an auxiliary power supply 503. The electronic machine 500 and the electronic component 501 are respectively electrical machines (electronic devices).

[0101] Electronic component 501 is driven by the main power supply 502. Examples of electronic component 501 include, for example, a CPU, a motor, a sensor terminal, and lighting. In the case where electronic component 501 is, for example, a CPU, the electronic machine 500 includes an electronic machine that can be controlled by a built-in host (CPU). In the case where electronic component 501 includes at least one of, for example, a motor, a sensor terminal, and lighting, the electronic machine 500 includes an electronic machine that can be controlled by an external host or a person.

[0102] The main power supply 502 is, for example, a battery. The battery may also include a rechargeable battery. The positive terminal (+) of the main power supply 502 is electrically connected to the Vcc terminal (Vcc) of the electronic component 501. The negative terminal (-) of the main power supply 502 is electrically connected to the GND terminal (GND) of the electronic component 501.

[0103] The auxiliary power supply 503 is a thermoelectric element 1. The thermoelectric element 1 includes at least one of the aforementioned thermoelectric elements 1. In the electronic device 500, the auxiliary power supply 503 is used in conjunction with, for example, the main power supply 502 to assist the power supply of the main power supply 502, or to serve as backup power for the main power supply 502 when the capacitor of the main power supply 502 is depleted. In the case of a battery that the main power supply 502 can charge, the auxiliary power supply 503 can also be used to charge the battery.

[0104] As shown in FIG6(b), the main power supply 502 can be provided as thermoelectric element 1. The electronic device 500 shown in FIG6(b) includes thermoelectric element 1 used as main power supply 502 and electronic components 501 that can be driven by thermoelectric element 1. The thermoelectric element 1 is an independent power source (e.g., grid-off power source). Therefore, the electronic device 500 can be, for example, a self-contained type (independent type). Moreover, the thermoelectric element 1 is an environmental power generation type (energy harvesting type). The electronic device 500 shown in FIG6(b) does not require battery replacement.

[0105] As shown in FIG6(c), the electronic component 501 may also include a thermoelectric element 1. The anode of the thermoelectric element 1 is electrically connected to, for example, the GND wiring of a circuit board (not shown). The cathode of the thermoelectric element 1 is electrically connected to, for example, the Vcc wiring of a circuit board (not shown). In this case, the thermoelectric element 1 can be used as, for example, an auxiliary power supply 503 for the electronic component 501.

[0106] As shown in FIG6(d), when the electronic component 501 has a thermoelectric element 1, the thermoelectric element 1 can be used as, for example, the main power supply 502 of the electronic component 501.

[0107] As shown in Figures 6(e) to 6(h), the electronic device 500 may also be equipped with a power generation device 100. The power generation device 100 includes a thermoelectric element 1 as a source of electrical energy.

[0108] The embodiment shown in FIG. 6(d) includes a thermoelectric element 1 whose electronic component 501 is used as a main power source 502. Similarly, the embodiment shown in FIG. 6(h) includes a power generation device 100 whose electronic component 501 is used as a main power source. In these embodiments, the electronic component 501 has an independent power source. Therefore, the electronic component 501 can be configured as, for example, a self-contained type. The self-contained electronic component 501 can be effectively used in, for example, electronic machines that include multiple electronic components, and at least one electronic component is separate from the other electronic components. An example of such an electronic machine 500 is a sensor. The sensor includes a sensor terminal (slave) and a controller (master) located remotely from the sensor terminal. Both the sensor terminal and the controller are electronic components 501. If the sensor terminal includes a thermoelectric element 1 or a power generation device 100, it becomes a self-contained sensor terminal and does not require wired power supply. Since the thermoelectric element 1 or the power generation device 100 is an ambient power generation type, battery replacement is not required. A sensor terminal can be considered as one of the electronic devices 500. In addition to sensors, sensor terminals considered as electronic devices 500 further include, for example, IoT wireless tags.

[0109] In the embodiments shown in Figures 6(a) to 6(h), the common feature is that the electronic machine 500 includes a thermoelectric element 1 that converts thermal energy into electrical energy, and an electronic component 501 that can use the thermoelectric element 1 to drive it by a power source.

[0110] The electronic device 500 can be an autonomous type with its own power supply. Examples of autonomous electronic devices include robots. Furthermore, the electronic component 501, which includes a thermoelectric element 1 or a power generation device 100, can also be an autonomous type with its own power supply. Examples of autonomous electronic components include motion sensor terminals. [Example]

[0111] Next, an embodiment related to the thermoelectric element 1 in the above-described embodiment will be described. In this embodiment, the time-dependent change in the current output from the element is measured.

[0112] In this embodiment, as Example 1, the current is measured using a thermoelectric element containing a layer of organic material representing orientation polarization, and as Comparative Example 1, the current is measured using a thermoelectric element not containing a layer of organic material representing orientation polarization.

[0113] In Example 1, a measuring element is formed using the manufacturing method based on the thermoelectric element 1 described above. ITO is used as the first electrode, and Al is used as the second electrode. Between the electrodes, a CuPC donor layer, a first acceptor layer using F16CuPc, a second acceptor layer using C60, and an electron transport layer using BCP are stacked. The distance between the electrodes is set to 100 nm.

[0114] In Comparative Example 1, the same elements as those in Comparative Example 1 of the second embodiment described in Japanese Patent No. 6845521 were formed. Pt was used as the first electrode, and Al was used as the second electrode. Toluene, in which Au nanoparticles were dispersed, was filled between the electrodes. The distance between the electrodes was set to 10 μm.

[0115]

[0116] Table 1 shows the results of the current measured at room temperature of the component formed under the above conditions. In this embodiment, the change in current over time is set as the evaluation object. In Table 1, the current at the reference time (t0: 40 seconds from the start of measurement) excluding the initial measurement is used as the reference, and the currents at t1=60 seconds, t2=80 seconds, and t3=100 seconds are expressed as relative values.

[0117] As shown in Table 1, in Comparative Example 1, it was found that there was a tendency for the current value to decrease over time. In contrast, in Example 1, it was found that the tendency for the current value to decrease over time was suppressed compared to Comparative Example 1. Therefore, when using the element of Example 1, a stable power generation efficiency can be obtained. Furthermore, even in the thermoelectric element 1 of the above-described embodiment having the same configuration as Example 1, a stable power generation efficiency can also be obtained.

[0118] Although several embodiments of the present invention have been described, these embodiments are merely illustrative and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made as long as they do not depart from the spirit of the invention. These embodiments or their variations are included within the scope or spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents. [Simplified Explanation of the Diagram]

[0028] [Fig. 1(a) and Fig. 1(b)] are schematic cross-sectional views showing an example of a thermoelectric element and a power generation device in the first embodiment. [Fig. 2(a) and Fig. 2(b)] are schematic diagrams showing an example of the electronic state of each component of the thermoelectric element. [Fig. 3] is a flowchart showing an example of a manufacturing method of the thermoelectric element in the first embodiment. [Fig. 4(a) and Fig. 4(b)] are schematic cross-sectional views showing a modified example of the thermoelectric element in the first embodiment. [Fig. 5] is a schematic cross-sectional view showing an example of a thermoelectric element in the second embodiment. [Fig. 6(a) to Fig. 6(d)] are schematic block diagrams showing an example of an electronic machine equipped with a thermoelectric element, and [Fig. 6(e) to Fig. 6(h)] are schematic block diagrams showing an example of an electronic machine equipped with a power generation device including a thermoelectric element.

Claims

1. A thermoelectric element that does not require a temperature difference between electrodes, comprising: a first electrode; a second electrode disposed spaced apart from the first electrode; a donor layer comprising at least one layer disposed between the first electrode and the second electrode; and an acceptor layer comprising at least one layer disposed between the donor layer and the second electrode, wherein at least one of the donor layer and the acceptor layer comprises an organic material representing orientation polarization.

2. The thermoelectric element of claim 1, wherein the work function of the first electrode is higher than the work function of the second electrode.

3. The thermoelectric element of claim 2, wherein the donor layer and the acceptor layer are solid.

4. The thermoelectric element of any one of claims 1 to 3, wherein the LUMO (Lowest Unoccupied Molecular Orbital) of the acceptor layer is between the HOMO (Highest Occupied Molecular Orbital) and the LUMO of the donor layer, and the HOMO of the acceptor layer is higher than the HOMO of the donor layer.

5. A thermoelectric element according to any one of claims 1 to 3, wherein the acceptor layer comprises: a first acceptor layer in contact with the donor layer; a second acceptor layer disposed between the first acceptor layer and the second electrode; and an electron transport layer disposed between the second acceptor layer and the second electrode, wherein at least one of the first acceptor layer, the second acceptor layer and the electron transport layer comprises an organic material representing orientation polarization.

6. The thermoelectric element of any one of claims 1 to 3, wherein the acceptor layer comprises a hybrid layer in contact with the donor layer, thereby mixing the two types of materials.

7. A power generation device comprising: the thermoelectric element described in claim 1; a first wiring electrically connected to the first electrode; and a second wiring electrically connected to the second electrode.

8. An electronic machine comprising: the thermoelectric element described in claim 1; and electronic components that drive the thermoelectric element by using a power source.

9. A method for manufacturing a thermoelectric element that does not require a temperature difference between electrodes, comprising: a first electrode forming process for forming a first electrode; a donor layer forming process for forming a donor layer comprising at least one layer; an acceptor layer forming process for forming an acceptor layer comprising at least one layer; and a second electrode forming process for forming a second electrode, wherein at least one of the donor layer and the acceptor layer comprises an organic material representing orientation polarization.

10. The method for manufacturing a thermoelectric element as claimed in claim 9, wherein the donor layer formation process is to form the donor layer on the surface of the first electrode, the acceptor layer formation process is to form the acceptor layer on the surface of the donor layer, the second electrode formation process is to form the second electrode on the surface of the acceptor layer under reduced pressure, and the work function of the first electrode is higher than that of the second electrode.

11. A method for manufacturing a thermoelectric element as claimed in claim 9 or 10, wherein the acceptor layer forming process comprises: forming a first acceptor layer on the surface of the donor layer; forming a second acceptor layer on the surface of the first acceptor layer; and forming an electron transport layer on the surface of the second acceptor layer, wherein the second electrode forming process comprises forming the second electrode on the surface of the electron transport layer, and at least any one of the first acceptor layer, the second acceptor layer, and the electron transport layer comprises an organic material representing orientation polarization.

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