Photoelectric conversion device and flying object

Abstract

To provide a solar cells are desired to effectively utilize light in the ultraviolet region.SOLUTION: The present invention provides a photoelectric conversion device including: a tandem-type photoelectric conversion element in which a first photoelectric conversion part that converts light energy of incident light into an electric energy, and a second photoelectric conversion part disposed on a light receiving surface side of the first photoelectric conversion part are stacked; and a wavelength conversion part disposed on a light receiving surface side of the second photoelectric conversion part. The wavelength conversion part includes a wavelength conversion material that converts a wavelength less than 400 nm into an absorption wavelength of the second photoelectric conversion part. The present invention provides a flying object, comprising: a photoelectric conversion device; and a propulsive force generation device that utilizes electrical energy generated by the photoelectric conversion device to generate a propulsive force.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] The present invention relates to a photoelectric conversion device and an aircraft. [Background technology]

[0002] Patent Documents 1 to 6 disclose solar cells provided with a wavelength conversion layer containing one or more wavelength conversion materials. [Prior art document] [Patent documents] [Patent Document 1] Japanese Patent Application Publication No. 07-142752 [Patent Document 2] JP 2016-145295 A [Patent Document 3] JP 2019-215451 A [Patent Document 4] JP 2019-050381 A [Patent Document 5] JP 2022-056319 A [Patent Document 6] JP 2013-069728 A Summary of the Invention [Problem to be solved by the invention]

[0003] It is desirable for solar cells to effectively utilize light in the ultraviolet region. [Means for solving the problem]

[0004] In a first aspect of the present invention, there is provided a photoelectric conversion device. The photoelectric conversion device may include a tandem photoelectric conversion element in which a first photoelectric conversion unit that converts the optical energy of incident light into electrical energy and a second photoelectric conversion unit disposed on the light-receiving surface side of the first photoelectric conversion unit are stacked. The photoelectric conversion device may include a wavelength conversion unit disposed on the light-receiving surface side of the second photoelectric conversion unit. The wavelength conversion unit may include a wavelength conversion material that converts wavelengths shorter than 400 nm to the absorption wavelength of the second photoelectric conversion unit.

[0005] In the photoelectric conversion device, the wavelength conversion section may convert a wavelength of less than 400 nm into a wavelength of 400 nm or more.

[0006] In any of the photoelectric conversion devices described above, the wavelength conversion section may convert the wavelength of light having a wavelength of less than 400 nm into a wavelength within the absorption wavelength range of the second photoelectric conversion section.

[0007] In any of the above photovoltaic devices, the photovoltaic element may include at least two of a silicon-based photovoltaic element, a III-V-based photovoltaic element, a perovskite-type photovoltaic element, a CIS solar cell, a CIGS solar cell, a dye-sensitized photovoltaic element, an organic thin-film photovoltaic element, or a cuprous oxide solar cell.

[0008] In any of the photoelectric conversion devices described above, an upper limit value of the absorption wavelength range of the second photoelectric conversion section may be lower than an upper limit value of the absorption wavelength range of the first photoelectric conversion section.

[0009] In any of the above photoelectric conversion devices, the photoelectric conversion element may have a two-terminal structure.

[0010] In any of the above photoelectric conversion devices, the photoelectric conversion element may have a four-terminal structure or a three-terminal structure.

[0011] In any of the photoelectric conversion devices described above, the wavelength conversion material may include at least one of an organic dye, a rare earth complex, an inorganic crystal or glass doped with a luminescent ion, inorganic phosphor nanoparticles, quantum dots, and oxide phosphor nanoparticles.

[0012] In any of the above photoelectric conversion devices, the wavelength conversion section may include a first wavelength conversion layer disposed on at least the light-receiving surface side of the second photoelectric conversion section and configured to convert the wavelength of light in a predetermined first wavelength region. The wavelength conversion section may include a second wavelength conversion layer disposed on the light-receiving surface side of the first wavelength conversion layer and configured to convert the wavelength of light in a predetermined second wavelength region. An upper limit value of the first wavelength region may be different from an upper limit value of the second wavelength region. A lower limit value of the first wavelength region may be different from a lower limit value of the second wavelength region.

[0013] In any of the photoelectric conversion devices described above, the first wavelength range may include a wavelength range of 100 nm or more and 400 nm or less, and the second wavelength range may include a wavelength range of 100 nm or more and 400 nm or less.

[0014] In any of the photoelectric conversion devices described above, the first wavelength range may include a wavelength range of 200 nm or more and 400 nm or less, and the second wavelength range may include a wavelength range of 200 nm or more and 400 nm or less.

[0015] Any of the above photoelectric conversion devices may include a sealing layer that seals the photoelectric conversion element. Any of the above photoelectric conversion devices may include a surface protection layer disposed on a light-receiving surface side of the sealing layer. The sealing layer and the surface protection layer may function as the wavelength conversion section.

[0016] Any of the above photoelectric conversion devices may include a sealing layer that seals the photoelectric conversion element. Any of the above photoelectric conversion devices may include a surface protection layer disposed on a light-receiving surface side of the sealing layer. The surface protection layer may function as the wavelength conversion section and include a plurality of wavelength conversion layers.

[0017] In any of the photoelectric conversion devices described above, the photovoltaic element of the second photoelectric conversion section may be thinner than the photovoltaic element of the first photoelectric conversion section.

[0018] In a second aspect of the present invention, there is provided an aircraft. The aircraft may include any of the photoelectric conversion devices according to the first aspect. The aircraft may include a thrust generating device that generates thrust using the electrical energy generated by the photoelectric conversion device.

[0019] The above summary of the invention does not list all of the necessary features of the present invention, and subcombinations of these features may also constitute inventions. [Brief explanation of the drawings]

[0020] [Figure 1]1 shows a schematic diagram of an example of the system configuration of an aircraft 100. [Figure 2A] 2 shows an example of the internal configuration of a photoelectric conversion device 200. [Figure 2B] 1 shows a modified example of the photoelectric conversion device 200. [Figure 3A] 1 shows a modified example of the photoelectric conversion device 200. [Figure 3B] 1 shows a modified example of the photoelectric conversion device 200. [Figure 3C] 1 shows a modified example of the photoelectric conversion device 200. [Figure 4] An example of the EQE characteristics of a photoelectric conversion device 200 having a two-terminal structure is shown. [Figure 5] An example of the EQE characteristics of a photoelectric conversion device 200 having another two-terminal structure is shown. DETAILED DESCRIPTION OF THE INVENTION

[0021] The light energy of some wavelengths of light incident on a solar cell may not be converted into electrical energy and may not be utilized. For example, even if light in the ultraviolet region is incident on a solar cell, it may not be converted by the photoelectric conversion element, and the light energy of the ultraviolet region may not be fully utilized. According to the exemplary embodiments disclosed in this specification, the wavelength of the incident light is converted into the absorption wavelength of the photoelectric conversion element and utilized, thereby increasing the amount of power generation and enabling more energy to be utilized effectively.

[0022] In aircraft flying in the stratosphere using solar energy, the amount of energy generated by existing solar cells may limit the flight area and / or service quality. The intensity of ultraviolet light in the stratosphere is comparable to that in space, causing the performance of solar cells to deteriorate more quickly than on Earth. Cutting ultraviolet light to ensure durability means that energy in that wavelength range cannot be utilized. According to the exemplary embodiments disclosed herein, by converting and utilizing the wavelength of incident light, it is possible to increase the amount of power generated and provide more energy to the aircraft while ensuring the durability of the aircraft.

[0023] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0024] (Overview of the flying vehicle 100) 1 shows a schematic diagram of an example of the system configuration of an aircraft 100. In this embodiment, the aircraft 100 includes a power generation system 110, a power control circuit 120, a power storage device 130, a thrust generating device 140, a sensor 150, and a control device 160. The power generation system 110 of this example includes a photoelectric conversion device 200.

[0025] The flying object 100 flies using electrical energy generated by the power generation system 110. In this embodiment, the electrical energy generated by the power generation system 110 may be stored in the power storage device 130. The flying object 100 may fly using the electrical energy stored in the power storage device 130. Examples of the flying object 100 include an airplane, an airship or balloon, a balloon, a helicopter, and a drone.

[0026] The power generation system 110 generates electric power using a photoelectric conversion device 200. The power generation system 110 of this example supplies the generated electric power to the power storage device 130 and / or the propulsion generating device 140 via a power control circuit 120. The photoelectric conversion device 200 generates electric power by converting the optical energy of incident light into electrical energy. The photoelectric conversion device 200 may have one or more solar power generation modules. The photoelectric conversion device 200 may be used in the stratosphere, or on the earth's surface, including on land or sea.

[0027] The power storage device 130 may store electrical energy. For example, the power storage device 130 stores electrical energy generated by the power generation system 110. The power storage device 130 may also release the stored electrical energy. For example, the power storage device 130 supplies power to the electric motor 142. The power storage device 130 may include a secondary battery.

[0028] The power control circuit 120 controls the output of power generated by the power generation system 110. The power control circuit 120 may control the input and output of power of the power storage device 130. In one embodiment, the power control circuit 120 supplies the power generated by the power generation system 110 to the power storage device 130 and / or the electric motor 142. The power control circuit 120 may supply the power stored in the power storage device 130 to the electric motor 142. The power control circuit 120 may control the input and / or output of the power based on commands from the control device 160. The power control circuit 120 may include, for example, one or more switching elements that operate based on control signals from the control device 160. The power control circuit 120 may include one or more power conversion devices that operate based on control signals from the control device 160.

[0029] The thrust generating device 140 generates thrust using the electric energy generated by the photoelectric conversion device 200. The thrust generating device 140 may include an electric motor 142 and a propeller 144. The thrust generating device 140 may include multiple electric motors 142 and multiple propellers 144.

[0030] The electric motor 142 receives electrical energy from the power generation system 110 and / or the power storage device 130 via the power control circuit 120. The electric motor 142 uses the electrical energy received from the power generation system 110 and / or the power storage device 130 to rotate the propeller 144. In this way, the electric motor 142 can generate propulsion force for the aircraft 100 using the electrical energy generated by the power generation system 110.

[0031] The sensor 150 measures various physical quantities related to the position and attitude of the flying object 100. Examples of sensors for measuring various physical quantities related to the position and attitude of the flying object 100 include a GPS signal receiver, an acceleration sensor, an angular acceleration sensor, and a gyro sensor. The sensor 150 may measure various physical quantities related to the state of the power generation system 110 and / or the power storage device 130. Examples of sensors for measuring various physical quantities related to the state of the power generation system 110 and / or the power storage device 130 include a temperature sensor, a current sensor, and a voltage sensor.

[0032] The control device 160 controls the air vehicle 100. The control device 160 may control the power output of the power generation system 110 by controlling the power control circuit 120. For example, the control device 160 controls the output power, output current, output voltage, etc. of the power generation system 110. The control device 160 may control the input / output of power to the power storage device 130 by controlling the power control circuit 120. For example, the control device 160 controls the output power, output current, output voltage, input power, input current, input voltage, etc. of the power storage device 130. In this way, the control device 160 can control the position and attitude of the air vehicle 100. The control device 160 may control the position and attitude of the air vehicle 100 by controlling the power control circuit 120 based on the output from the sensor 150.

[0033] The photoelectric conversion device 200 of this example has a photoelectric conversion element 300 and a wavelength conversion section 400. In addition to the photoelectric conversion element 300 and the wavelength conversion section 400, the photoelectric conversion device 200 may have other components such as a sealing layer. The specific structure of the photoelectric conversion device 200 will be described later. Note that, although the photoelectric conversion device 200 of this example has been described as being mounted on the aircraft 100, this is not limiting. The photoelectric conversion device 200 may be mounted on a moving object such as an automobile, bicycle, train, or ship. The photoelectric conversion device 200 may be used while fixed to the ground or a structure. The power generated by the photoelectric conversion device 200 may be stored in any power storage device.

[0034] The photoelectric conversion element 300 converts the optical energy of incident light into electrical energy. The photoelectric conversion element 300 may convert optical energy into electrical energy using the photovoltaic effect. The photoelectric conversion element 300 may include a silicon-based photovoltaic element, a III-V-based photovoltaic element, a perovskite-type photovoltaic element, a CIS solar cell, a CIGS solar cell, a dye-sensitized photovoltaic element, an organic thin-film photovoltaic element, or a cuprous oxide solar cell. The photoelectric conversion element 300 may have a tandem structure in which multiple photoelectric conversion elements are stacked. In one example, the photoelectric conversion element 300 has a tandem structure selected from at least two of a silicon-based photovoltaic element, a III-V-based photovoltaic element, a perovskite-type photovoltaic element, a CIS solar cell, a CIGS solar cell, a dye-sensitized photovoltaic element, an organic thin-film photovoltaic element, or a cuprous oxide solar cell.

[0035] The conversion efficiency of a photoelectric conversion element depends on the wavelength of the incident light. For example, a silicon-based photoelectric conversion element can convert light in the wavelength range from visible light to near-infrared light relatively efficiently, but may not be able to efficiently convert light in the wavelength range corresponding to ultraviolet light. The photoelectric conversion element 300 may have multiple photoelectric conversion elements with different conversion efficiencies. In this specification, when a numerical range is expressed as "A to B," this expression means A or more and B or less.

[0036] The wavelength conversion section 400 converts light incident on the photoelectric conversion device 200 into light of a predetermined wavelength. The wavelength conversion section 400 may emit light of a wavelength at which the conversion efficiency by the photoelectric conversion element 300 is relatively good. The wavelength conversion section 400 may convert a wavelength of less than 400 nm into an absorption wavelength of the photoelectric conversion element 300. The wavelength conversion section 400 may convert a wavelength of 100 nm or more and less than 400 nm into an absorption wavelength of the photoelectric conversion element 300, a wavelength of 200 nm or more and less than 400 nm into an absorption wavelength of the photoelectric conversion element 300, or a wavelength of 300 nm or more and less than 400 nm into an absorption wavelength of the photoelectric conversion element 300.

[0037] The wavelength conversion section 400 may also convert light with a wavelength of 400 nm or more to a wavelength absorbed by the photoelectric conversion element 300. The wavelength conversion section 400 may convert a wavelength of 100 nm or more and 500 nm or less to a wavelength absorbed by the photoelectric conversion element 300, a wavelength of 200 nm or more and 500 nm or less to a wavelength absorbed by the photoelectric conversion element 300, or a wavelength of 300 nm or more and 500 nm or less to a wavelength absorbed by the photoelectric conversion element 300. When the photoelectric conversion element 300 has multiple photoelectric conversion elements, the absorption wavelength of the photoelectric conversion element 300 may be a wavelength that can be absorbed by any of the photoelectric conversion elements.

[0038] The wavelength converting section 400 may contain one or more materials having an excitation band in the wavelength range of 100 to 500 nm and an emission peak in the wavelength range of 380 to 780 nm. The wavelength converting section 400 may contain two or more wavelength converting materials. The wavelength converting section 400 may contain a material that emits blue light (wavelength 440 to 480 nm), a material that emits green light (wavelength 500 to 540 nm), a material that emits yellow light (wavelength 540 to 595 nm), or a material that emits red light (wavelength 600 to 700 nm).

[0039] Examples of wavelength converting materials for the wavelength converting unit 400 include organic dyes, rare earth complexes, inorganic crystals or glasses doped with luminescent ions, inorganic phosphor nanoparticles, quantum dots, and oxide phosphor nanoparticles. Quantum dots may be semiconductor particles with a size that exhibits a quantum confinement effect. The wavelength converting material for the wavelength converting unit 400 may include at least one of an inorganic phosphor and an organic phosphor.

[0040] Examples of organic fluorescent materials include organic dyes and luminescent rare earth complexes, and examples of luminescent rare earth complexes include lanthanide complexes such as Eu(III) complexes.

[0041] The inorganic phosphor may be at least one selected from the group consisting of oxide phosphors, nitride phosphors, oxynitride phosphors, chloride phosphors, oxychloride phosphors, sulfide phosphors, halide phosphors, aluminate phosphors, halophosphate chloride phosphors, and silica-based phosphors. Silica-based phosphors are phosphors in which silica is used as the main component of the matrix of the fluorescent light-emitting material, and examples of silica-based phosphors include composite oxides containing particulate silica and a europium compound. The silica-based phosphor may also contain aluminum and europium.

[0042] As an inorganic phosphor that has an excitation band in the ultraviolet to near ultraviolet wavelength range of 300 to 440 nm and emits blue light, (Sr,Ba)MgAl 10 O 17 :EU 2+ , (Sr,Ba)3MgSi2O8:Eu 2+ Examples of inorganic phosphors that have an excitation band in the ultraviolet to near ultraviolet wavelength range of 300 to 440 nm and emit green light include SrAl2O4:Eu 2+ , SrBaSiO4:Eu 2+ , Y3(Al,Gd)5O 12 :Ce 3+ , SrSiON:Eu 2+ , BaMgAl 10 O 17 :EU 2+ ,Mn 2+ , Ba2MgSi2O7:Eu 2+ , Ba2SiO4:Eu 2+ , Ba2Li2Si2O7:Eu 2+ , BaAl2O4:Eu 2+ Examples of inorganic phosphors that have an excitation band in the ultraviolet to near ultraviolet wavelength range of 300 to 440 nm and emit yellow light include La3Si6N 11 :Ce 3+ Examples of inorganic phosphors that have an excitation band in the ultraviolet to near ultraviolet wavelength range of 300 to 440 nm and emit red light include MgSr3Si2O8:Eu 2+ ,Mn 2+ , Ca2MgSi2O7:Eu 2+ ,Mn 2+ Examples include:

[0043] As an inorganic phosphor that has an excitation band in the blue region of wavelength 440 to 480 nm and emits green light, SrAl2O4:Eu 2+ , SrBaSiO4:Eu 2+ , Y3(Al,Gd)5O 12 :Ce 3+ , SrSiON:Eu 2+ , β-SiAlON:Eu 2+ Examples of inorganic phosphors that have an excitation band in the blue region of wavelengths of 440 to 480 nm and emit yellow light include Y3(Al,Gd)5O 12 :Ce 3+ , Sr2SiO4:Eu 2+ Examples of inorganic phosphors that have an excitation band in the blue region of wavelengths of 440 to 480 nm and emit red light include CaAlSiN3:Eu 2+ , CaSiN3:Eu 2+ , (Ca,Sr)2Si5N8:Eu 2+ , α-SiAlON:Eu 2+ Examples include:

[0044] (Outline of photoelectric conversion device 200) 2A schematically illustrates an example of the internal configuration of a photoelectric conversion device 200. The photoelectric conversion device 200 of this example has a front surface 202 and a back surface 204. The photoelectric conversion device 200 includes, for example, a front surface protective layer 210, a sealing layer 220, a back surface protective layer 230, and a photoelectric conversion element 300. The photoelectric conversion element 300 of this example has a front surface 302, a back surface 304, and a side surface 306.

[0045] The photoelectric conversion element 300 has a light-receiving surface electrode 310, a photovoltaic element 320, a back surface electrode 330, a negative electrode terminal 362, and a positive electrode terminal 364. The photoelectric conversion element 300 in this example has a two-terminal structure with the negative electrode terminal 362 and the positive electrode terminal 364, but may have a three-terminal structure or a four-terminal structure.

[0046] The photovoltaic element 320 includes a first photoelectric conversion section 321 and a second photoelectric conversion section 322. The photovoltaic element 320 of this example has a tandem structure in which the first photoelectric conversion section 321 and the second photoelectric conversion section 322 are stacked. The first photoelectric conversion section 321 and the second photoelectric conversion section 322 may be different types of photovoltaic elements.

[0047] The first photoelectric conversion unit 321 converts the optical energy of incident light into electrical energy. The first photoelectric conversion unit 321 may be any of a silicon-based photovoltaic element, a III-V-based photovoltaic element, a perovskite-type photovoltaic element, a CIS solar cell, a CIGS solar cell, a dye-sensitized photovoltaic element, an organic thin-film photovoltaic element, and a cuprous oxide solar cell. In one example, the first photoelectric conversion unit 321 is a silicon-based photovoltaic element. The first photoelectric conversion unit 321 may include an n-type semiconductor layer and a p-type semiconductor layer. The silicon-based photovoltaic element may be a photovoltaic element using single crystal silicon or a photovoltaic element using polycrystalline silicon.

[0048] The second photoelectric conversion unit 322 converts the optical energy of incident light into electrical energy. The second photoelectric conversion unit 322 is disposed on the light-receiving surface side of the first photoelectric conversion unit 321. That is, the second photoelectric conversion unit 322 may receive light that enters the photoelectric conversion device 200 before the first photoelectric conversion unit 321. The second photoelectric conversion unit 322 may have an n-type semiconductor layer and a p-type semiconductor layer. The second photoelectric conversion unit 322 may be any of a silicon-based photovoltaic element, a III-V-based photovoltaic element, a perovskite-type photovoltaic element, a CIS solar cell, a CIGS solar cell, a dye-sensitized photovoltaic element, an organic thin-film photovoltaic element, and a cuprous oxide solar cell. The second photoelectric conversion unit 322 may be a perovskite-type photovoltaic element or a cuprous oxide solar cell. In one example, the second photoelectric conversion unit 322 is a perovskite-type photovoltaic element. The perovskite photovoltaic element may include an n-type semiconductor layer, a perovskite layer, and a p-type semiconductor layer.

[0049] Any combination of the first photoelectric conversion section 321 and the second photoelectric conversion section 322 may be used. In one example, the first photoelectric conversion section 321 is a silicon-based photovoltaic element, and the second photoelectric conversion section 322 is a perovskite-type photovoltaic element. Alternatively, the first photoelectric conversion section 321 may be a CIGS solar cell, and the second photoelectric conversion section 322 may be a perovskite-type photovoltaic element.

[0050] The first photoelectric conversion section 321 and the second photoelectric conversion section 322 may have different absorption wavelength ranges. The first photoelectric conversion section 321 and the second photoelectric conversion section 322 may have absorption wavelength ranges with different upper and / or lower limits. The upper limit of the absorption wavelength range of the second photoelectric conversion section 322 may be lower than the upper limit of the absorption wavelength range of the first photoelectric conversion section 321. The lower limit of the absorption wavelength range of the second photoelectric conversion section 322 may be lower than the lower limit of the absorption wavelength range of the first photoelectric conversion section 321. In the photoelectric conversion element 300, incident light may be absorbed first by the second photoelectric conversion section 322, and the unabsorbed light may be absorbed by the first photoelectric conversion section 321.

[0051] The light-receiving surface electrode 310 is disposed on the light-receiving surface side of the photovoltaic element 320. The light-receiving surface electrode 310 may be electrically connected to the n-type semiconductor layer of the second photoelectric conversion section 322. The light-receiving surface electrode 310 may be a comb-shaped electrode having finger regions and busbar regions. The light-receiving surface electrode 310 may have a transparent electrode material such as ITO (indium tin oxide) or FTO (fluorine-doped tin oxide).

[0052] The back electrode 330 is disposed on the side opposite to the light-receiving surface side of the photovoltaic element 320. The back electrode 330 may be electrically connected to the p-type semiconductor layer of the first photoelectric conversion section 321. The back electrode 330 may have a different material from the light-receiving surface electrode 310.

[0053] The negative electrode terminal 362 is electrically connected to the light-receiving surface electrode 310. The positive electrode terminal 364 is electrically connected to the back surface electrode 330.

[0054] The encapsulation layer 220 encapsulates the photoelectric conversion element 300. The encapsulation layer 220 protects the photoelectric conversion element 300 from, for example, oxygen and moisture. The encapsulation layer 220 may encapsulate a portion of the photoelectric conversion element 300, or may encapsulate the entire photoelectric conversion element 300. The encapsulation layer 220 may be arranged to cover at least a portion of the surface 302 of the photoelectric conversion element 300. The encapsulation layer 220 may be arranged to cover at least a portion of the side surface 306 of the photoelectric conversion element 300.

[0055] The encapsulating layer 220 in this example encapsulates the entire photoelectric conversion element 300. In this case, a portion of the encapsulating layer 220 is disposed between the front surface 302 of the photoelectric conversion element 300 and the front surface protection layer 210. Similarly, a portion of the encapsulating layer 220 may be disposed between the rear surface 304 of the photoelectric conversion element 300 and the rear surface protection layer 230. The encapsulating layer 220 may cover the entire side surface 306 of the photoelectric conversion element 300.

[0056] The sealing layer 220 in this example includes a wavelength converting material 225. The sealing layer 220 may be a film or coating made of the wavelength converting material 225, or may be a film or coating containing the wavelength converting material 225 and a resin material. The sealing layer 220 in this example functions as the wavelength converting section 400. The wavelength converting material 225 may include at least one of an organic dye, a rare earth complex, an inorganic crystal or glass doped with a luminescent ion, inorganic phosphor nanoparticles, quantum dots, and oxide phosphor nanoparticles.

[0057] The thickness of the sealing layer 220 may be 20 μm or more and 400 μm or less. The thickness of the sealing layer 220 may be 20 μm or more and 100 μm or less. This reduces the mass of the photovoltaic device 200. The thickness of the sealing layer 220 is set so that the mass of the sealing layer 220 is 800 g / m 2 The thickness of the sealing layer 220 may be determined such that the mass of the surface protection layer 210 and the sealing layer 220 is 1000 g / m 2 The thickness of the sealing layer 220 may be determined so that the mass of the photovoltaic device 200 is 1200 g / m 2 The thickness of the sealing layer 220 may be determined so that the mass of the photovoltaic device 200 is 500 g / m2 The mass of the photovoltaic conversion device 200 may be determined as follows: The mass of the photovoltaic conversion device 200 may be the mass per installation area of the photovoltaic conversion device 200, or may be the mass per area of the solar power generation panel.

[0058] The wavelength conversion section 400 may have one or more wavelength conversion layers WL. The wavelength conversion layer WL may be provided at any position in the photoelectric conversion device 200. The wavelength conversion layer WL may be a layer on the light-receiving surface side of the photoelectric conversion element 300. The wavelength conversion layer WL may be disposed on the light-receiving surface side of the second photoelectric conversion section 322. The wavelength conversion section 400 may include at least one of the sealing layer 220 or the surface protection layer 210. The wavelength conversion layer WL may be a layer other than the sealing layer 220 and the surface protection layer 210.

[0059] The wavelength conversion layer WL converts the wavelength of light by, for example, down-conversion, up-conversion, or nonlinear optical effects. An up-conversion material that converts the wavelength of light by using the up-conversion phenomenon is excited, for example, with light or electromagnetic waves of a specific wavelength and emits light with a wavelength shorter than the wavelength of the light or electromagnetic waves. A down-conversion material that converts the wavelength of light by using the down-conversion phenomenon is excited, for example, with light or electromagnetic waves of a specific wavelength and emits light with a wavelength longer than the wavelength of the light or electromagnetic waves.

[0060] The wavelength conversion layer WL may emit light of a wavelength that is converted relatively efficiently by the photoelectric conversion element 300. In particular, the wavelength conversion layer WL may emit light of a wavelength that is converted relatively efficiently by the second photoelectric conversion section 322. For example, the wavelength conversion layer WL may convert a wavelength less than 400 nm to a wavelength absorbed by the second photoelectric conversion section 322. The wavelength conversion layer WL may convert a wavelength less than 400 nm to a wavelength equal to or greater than 400 nm. The wavelength conversion layer WL may convert a wavelength less than 400 nm into a wavelength within the absorption wavelength range of the second photoelectric conversion section 322. "Conversion into the absorption wavelength range of the second photoelectric conversion section 322" may mean that the wavelength range of light after conversion by the wavelength conversion layer WL is included in the absorption wavelength range of the second photoelectric conversion section 322.

[0061] Here, the content of the wavelength converting material 225 in the sealing layer 220 may be 10% by mass or less, or may be 1 to 8% by mass. When the content of the wavelength converting material 225 is within the above numerical range, for example, even if the thickness of the sealing layer 220 is 20 μm or more and 100 μm or less, it is possible to convert a sufficient amount of ultraviolet light into visible light or near-infrared light to improve the conversion efficiency of the photoelectric conversion element 300. This can improve, for example, the conversion efficiency on the ground by 2% or more. Also, the conversion efficiency in a stratospheric environment can improve by 4% or more.

[0062] The content of the wavelength converting material 225 may be determined in consideration of the transmittance of the sealing layer 220 to ultraviolet light. The content of the wavelength converting material 225 is determined, for example, so that the transmittance of the sealing layer 220 to light having a wavelength of 250 nm to 1600 nm is 90% or more. The content of the wavelength converting material 225 may be determined so that the transmittance of the sealing layer 220 to light having a wavelength of 250 nm to 1600 nm is 80% or more. The above transmittance is measured, for example, by an ultraviolet-visible-near-infrared spectrophotometer. The sealing layer 220 may be an example of a layer containing the wavelength converting material 225. In one embodiment, the transmittance of the sealing layer 220 to ultraviolet light is 80% or more, and the transmittance of the surface protection layer 210 to ultraviolet light is 90% or more. In another embodiment, the transmittance of the sealing layer 220 to ultraviolet light is 90% or more, and the transmittance of the surface protection layer 210 to ultraviolet light is 90% or more.

[0063] The surface protective layer 210 is disposed on the light-receiving surface side of the sealing layer 220. That is, the surface protective layer 210 is disposed closer to the light-incident side than the sealing layer 220. The surface protective layer 210 protects the sealing layer 220 from the external environment. The surface protective layer 210 may protect the sealing layer 220 from oxygen. The surface protective layer 210 may protect the sealing layer 220 from temperature changes or low temperatures. The surface protective layer 210 may protect the sealing layer 220 from impacts due to changes in air pressure, wind pressure, and the like. The surface protective layer 210 may be disposed in contact with the light-incident surface of the sealing layer 220. Another layer may be interposed between the surface protective layer 210 and the sealing layer 220. In the photovoltaic conversion device 200 of this example, light is incident on the surface protective layer 210 and the sealing layer 220 in that order.

[0064] The thickness of the surface protective layer 210 may be 20 μm or more and 200 μm or less. The thickness of the surface protective layer 210 may be 20 μm or more and 50 μm or less. By reducing the thickness of the surface protective layer 210, the mass of the photovoltaic device 200 is reduced. The thickness of the surface protective layer 210 is set so that the mass of the surface protective layer 210 is 500 g / m 2 The thickness of the surface protection layer 210 may be determined such that the mass of the surface protection layer 210 and the sealing layer 220 is 800 g / m 2 The thickness of the surface protection layer 210 may be determined so that the mass of the photovoltaic device 200 is 1200 g / m 2 The thickness of the surface protection layer 210 may be determined so that the mass of the photovoltaic device 200 is 500 g / m 2 The mass of the photovoltaic conversion device 200 may be determined as follows: The mass of the photovoltaic conversion device 200 may be the mass per installation area of the photovoltaic conversion device 200, or may be the mass per area of the solar power generation panel.

[0065] The back surface protection layer 230 is disposed on one of the two surfaces of the sealing layer 220 opposite the surface on which the front surface protection layer 210 is disposed. The two surfaces of the sealing layer 220 may be surfaces that are approximately perpendicular to the thickness direction of the sealing layer 220. The back surface protection layer 230 is disposed between the sealing layer 220 and the wing surface 20 of the aircraft 100.

[0066] The back surface protective layer 230 may be disposed in contact with the surface of the sealing layer 220 facing the blade surface 20. Another layer may be interposed between the back surface protective layer 230 and the sealing layer 220. The back surface protective layer 230 in this example is disposed in contact with the blade surface 20. However, another layer may be interposed between the back surface protective layer 230 and the blade surface 20.

[0067] The back surface protective layer 230 may bond the photoelectric conversion device 200 and the wing surface 20 of the aircraft 100. There are no particular limitations on the material and shape of the back surface protective layer 230. Examples of the back surface protective layer 230 include an adhesive, an adhesive layer containing an adhesive and a resin material, a pressure-sensitive adhesive, and an adhesive layer containing a pressure-sensitive adhesive and a resin material.

[0068] The photoelectric conversion device 200 converts light in a wavelength region where the conversion efficiency by the photoelectric conversion element 300 is relatively low into light in a wavelength region where the conversion efficiency by the photoelectric conversion element 300 is relatively high. The photoelectric conversion element 300 of this example converts incident light into light in a wavelength region where the conversion efficiency by the second photoelectric conversion section 322 is relatively high. This allows the photoelectric conversion device 200 to efficiently convert the optical energy of the incident light into electrical energy. As a result, the amount of power generation per unit mass of the photoelectric conversion device 200 is improved.

[0069] Here, in the stratospheric environment, where the amount of ultraviolet light is greater than in terrestrial environments, the photoelectric conversion device 200 can utilize ultraviolet light that would otherwise be unused, thereby further improving the amount of power generation per unit mass. Therefore, by installing the photoelectric conversion device 200 in an aircraft 100 that flies in the stratosphere, the flight distance, flight time, and / or latitude range of the aircraft 100 can be increased. By improving the power generation efficiency, the photoelectric conversion device 200 increases the energy available to the aircraft 100, allowing weight to be allocated to other components such as the power storage device 130. This allows the aircraft 100 to be equipped with high-performance devices that consume a lot of power.

[0070] The photovoltaic device 200 of this example can improve the durability of the photovoltaic element 300 and other layers by providing the wavelength conversion unit 400. Therefore, the photovoltaic device 200 can use a photovoltaic element that is relatively susceptible to ultraviolet light, such as a perovskite-type photovoltaic element. In this way, the photovoltaic device 200 of this example can improve durability to ultraviolet light while improving power generation efficiency.

[0071] When the photoelectric conversion element 300 has multiple photovoltaic elements, current matching between the multiple photovoltaic elements may be required. The photoelectric conversion device 200 of this example can match the current between the multiple photovoltaic elements by adjusting the wavelength conversion characteristics of the wavelength conversion layer WL in consideration of the characteristics of the photoelectric conversion elements 300. The photoelectric conversion device 200 may also match the current between the multiple photovoltaic elements by adjusting the wavelength conversion characteristics of the wavelength conversion layer WL in consideration of the solar spectrum of the environment in which it is used. The photoelectric conversion device 200 can further improve the conversion efficiency by improving the current matching of the photoelectric conversion elements 300.

[0072] For example, the structure of the photoelectric conversion device 200 is determined by taking into consideration the wavelength conversion characteristics of the wavelength conversion layer WL, the conversion efficiencies for each wavelength range of the first photoelectric conversion section 321 and the second photoelectric conversion section 322, the environment in which the photoelectric conversion device 200 is used, and other factors. The wavelength conversion material of the wavelength conversion layer WL may be determined by taking into consideration the current matching of the photoelectric conversion element 300, and the type, particle size, particle shape, sensitivity, and concentration of the wavelength conversion material may be adjusted. The wavelength conversion material of the wavelength conversion layer WL may be determined by taking into consideration the reflectance, transmittance, refractive index, conversion wavelength range, conversion efficiency, and other factors. Converting the wavelength in the wavelength conversion layer WL increases the amount of current generated in the second photoelectric conversion section 322, preventing a deterioration in the current matching of the photoelectric conversion element 300. This further improves the conversion efficiency of the photoelectric conversion device 200.

[0073] Furthermore, the type and thickness of the surface protection layer 210 may be adjusted, and the type and thickness of the sealing layer 220 may be adjusted, taking into consideration the current matching of the photoelectric conversion element 300. The surface protection layer 210 and the sealing layer 220 may be determined in consideration of the reflectance, transmittance, refractive index, compatibility with the wavelength conversion material, or the like.

[0074] When the second photoelectric conversion section 322 has a higher conversion efficiency at a wavelength relatively shorter than that of the first photoelectric conversion section 321, the wavelength conversion section 400 may convert light incident on the photoelectric conversion device 200 to the absorption wavelength of the second photoelectric conversion section 322. This makes it possible to narrow the wavelength conversion width and improve the wavelength conversion efficiency compared to conversion to the absorption wavelength of the first photoelectric conversion section 321.

[0075] (Composition of Surface Protection Layer 210) The surface protection layer 210 may contain a resin material. Examples of the resin material for the surface protection layer 210 include at least one selected from the group consisting of polyethylene (PE), ultra-high molecular weight polyethylene (U-PE), polymethyl methacrylic (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), fluorine-based resin, polyimide (PI), unsaturated polyester (UP), epoxy resin (EP), and silicone resin (SI). The molecular weight of the ultra-high molecular weight polyethylene (U-PE) may be approximately 1,000,000 to 7,000,000. Examples of the fluorine-based resin include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), perfluoroethylene propene copolymer (FEP), perfluoroalkoxyalkane (PFA), ethylene tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), ethylene chlorotrifluoroethylene copolymer (ECTFE), and polyvinyl fluoride (PVF).

[0076] Perfluoroalkoxyalkane (PFA) is sometimes called tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin. Perfluoroethylenepropene copolymer (FEP) is sometimes called tetrafluoroethylene-ethylene copolymer resin. Ethylene chlorotrifluoroethylene copolymer (ECTFE) is sometimes called trifluorochloroethylene-ethylene copolymer resin.

[0077] (Optical Properties of Surface Protection Layer 210) The surface protection layer 210 preferably has a refractive index similar to that of air or the atmosphere. For example, the surface protection layer 210 has a refractive index similar to that of air or the atmosphere in a stratospheric environment. Examples of the surface protection layer 210 include glass with a refractive index of approximately 1.45 to 1.46 and resin with a refractive index of approximately 1.42. An example of a resin with a refractive index of approximately 1.42 is ethylene-tetrafluoroethylene resin (ETFE resin).

[0078] The surface protective layer 210 may be substantially transparent to ultraviolet light. The transmittance of the surface protective layer 210 to light having a wavelength of 200 nm to 450 nm may be 90% or more, or may be 95% or more. The transmittance is measured, for example, by an ultraviolet-visible-near-infrared spectrophotometer.

[0079] The surface protective layer 210 may be substantially transparent to visible light and / or near-infrared light. The transmittance of the surface protective layer 210 to light having a wavelength of 380 nm to 780 nm may be 90% or more, and may be 95% or more. The surface protective layer 210 to light having a wavelength of 800 nm to 1600 nm may be 90% or more, and may be 95% or more. The above transmittance is measured, for example, by an ultraviolet-visible-near-infrared spectrophotometer.

[0080] (Physical Properties of Surface Protection Layer 210) The surface protection layer 210 may be made of a material that has a durability of approximately six months to two years in a stratospheric environment test. Examples of temperatures in the stratospheric environment are -88°C to 50°C. Examples of atmospheric pressure in the stratospheric environment are 2 kPa to 101.3 kPa. Examples of average atmospheric pressure in the stratospheric environment are 5 kPa or less. Examples of humidity in the stratospheric environment are 0% RH to ground humidity. Examples of ultraviolet rays irradiated in the stratospheric environment are UV-A, UV-B, and UV-C. Examples of ozone concentrations in the stratospheric environment are 2 ppm to 8 ppm. Water may be present in the stratospheric environment.

[0081] The surface protection layer 210 may have flexibility to the extent that it can be arranged along the wing surface shape of an aircraft flying in a stratospheric environment. The surface protection layer 210 may have flexibility to the extent that it can accommodate deflection and / or vibrations that occur when the aircraft flies in a stratospheric environment.

[0082] (Composition of sealing layer 220) In this embodiment, the sealing layer 220 includes a resin material (not shown) and a wavelength converting material 225. The resin material of the sealing layer 220 and the resin material of the surface protection layer 210 may be different in type and / or composition.

[0083] Various materials known as encapsulants for solar cells may be used as the resin material for the encapsulation layer 220. Examples of the resin material for the encapsulation layer 220 include at least one selected from ethylene-vinyl acetate copolymer resin (EVA), polyolefin elastomer (POE), silicone resin (SI), and ionomer resin.

[0084] (Optical Properties of Sealing Layer 220) The sealing layer 220 may have a refractive index greater than that of the surface protection layer 210. This reduces reflection loss. An example of the material for the sealing layer 220 is a resin with a refractive index of approximately 1.5 to 1.6. An example of a resin with a refractive index of approximately 1.5 to 1.6 is ethylene-vinyl acetate copolymer resin (EVA resin).

[0085] The sealing layer 220 may be substantially transparent to ultraviolet light. The transmittance of the sealing layer 220 to light having a wavelength of 200 nm to 450 nm may be 80% or more. The transmittance is measured, for example, by an ultraviolet-visible-near-infrared spectrophotometer.

[0086] The sealing layer 220 may be substantially transparent to visible light and / or near-infrared light. The transmittance of the sealing layer 220 to light having a wavelength of 380 nm to 780 nm may be 80% or more. The transmittance of the sealing layer 220 to light having a wavelength of 800 nm to 1600 nm may be 80% or more. The transmittance is measured, for example, by an ultraviolet-visible-near-infrared spectrophotometer.

[0087] 2B shows a modified example of the photoelectric conversion device 200. The photoelectric conversion device 200 of this example differs from the photoelectric conversion device 200 of FIG. 2A in that the surface protection layer 210 functions as the wavelength conversion section 400. In this example, differences from the photoelectric conversion device 200 of FIG. 2A will be particularly described, and other aspects may be the same as those of the photoelectric conversion device 200 of FIG. 2A. The sealing layer 220 of this example does not need to function as the wavelength conversion section 400.

[0088] The surface protection layer 210 includes a wavelength converting material 215 for converting the wavelength of light. The wavelength converting material 215 may include a material similar to the inorganic phosphor or organic phosphor described in relation to the wavelength converting unit 400. The surface protection layer 210 may be a film or coating made of the wavelength converting material 215, or may be a film or coating containing the wavelength converting material 215 and a resin material.

[0089] The content of the wavelength converting material 215 in the surface protective layer 210 may be 10% by mass or less, or may be 1 to 8% by mass. When the content of the wavelength converting material 215 is within the above numerical range, for example, even if the thickness of the surface protective layer 210 is 20 μm or more and 50 μm or less, a sufficient amount of ultraviolet light can be converted into visible light or near-infrared light to improve the conversion efficiency of the photoelectric conversion element 300.

[0090] The content of the wavelength converting material 215 may be determined in consideration of the transmittance of the surface protective layer 210 to ultraviolet light. The content of the wavelength converting material 215 may be determined so that the transmittance of the surface protective layer 210 to ultraviolet light is 90% or more. The content of the wavelength converting material 215 may be determined so that the transmittance of the surface protective layer 210 to light with a wavelength of 250 nm to 1600 nm is 90% or more, for example. The transmittance is measured, for example, by an ultraviolet-visible-near-infrared spectrophotometer.

[0091] 3A shows a modified example of photoelectric conversion device 200. Photoelectric conversion device 200 of this example differs from photoelectric conversion device 200 of FIGS. 2A and 2B in that both surface protection layer 210 and sealing layer 220 function as wavelength conversion section 400. In this example, differences from photoelectric conversion device 200 of FIGS. 2A and / or 2B will be particularly described, and other aspects may be the same as photoelectric conversion device 200 of FIGS. 2A and / or 2B.

[0092] The sealing layer 220 includes a wavelength conversion material 225. The sealing layer 220 is disposed on at least the light-receiving surface side of the second photoelectric conversion section 322 and is an example of a first wavelength conversion layer WL1 that converts the wavelength of light in a predetermined first wavelength region. The first wavelength conversion layer WL1 is an example of a wavelength conversion layer WL. The first wavelength conversion layer WL1 may be provided on a side surface side of the second photoelectric conversion section 322, or on a back surface side opposite the light-receiving surface of the second photoelectric conversion section 322.

[0093] The first wavelength conversion layer WL1 emits fluorescence upon being excited by or absorbing light in the first wavelength region. The first wavelength conversion layer WL1 may be excited by light incident on the photoelectric conversion device 200 and / or light emitted by the second wavelength conversion layer WL2, and emit light having a specific wavelength. The first wavelength conversion layer WL1 may be excited by light in the first wavelength region, and emit light having a longer wavelength than the excitation light. The first wavelength region may include a wavelength region of 100 nm or more and 400 nm or less, or may include a wavelength region of 200 nm or more and 400 nm or less.

[0094] The surface protective layer 210 includes a wavelength converting material 215. The surface protective layer 210 is disposed on the light receiving surface side of the first wavelength conversion layer WL1 and is an example of a second wavelength conversion layer WL2 that converts the wavelength of light in a predetermined second wavelength region. That is, the second wavelength conversion layer WL2 receives incident light before the first wavelength conversion layer WL1. The second wavelength conversion layer WL2 is an example of a wavelength conversion layer WL.

[0095] The second wavelength conversion layer WL2 emits fluorescence upon being excited by or absorbing light in the second wavelength region. The second wavelength conversion layer WL2 may be excited by light incident on the photoelectric conversion device 200 and emit light having a specific wavelength. The second wavelength conversion layer WL2 may be excited by light in the second wavelength region and emit light with a longer wavelength than the excitation light. The second wavelength region may include a wavelength region of 100 nm or more and 400 nm or less, or may include a wavelength region of 200 nm or more and 400 nm or less.

[0096] The second wavelength conversion layer WL2 may be a down-conversion material. In this example, light incident on the photoelectric conversion device 200 is incident on the second wavelength conversion layer WL2, the first wavelength conversion layer WL1, and the photoelectric conversion element 300 in that order. The second wavelength conversion layer WL2 converts the wavelength of light in the second wavelength region to a longer wavelength, thereby suppressing ultraviolet-induced deterioration of not only the photoelectric conversion element 300 but also the first wavelength conversion layer WL1.

[0097] In one example, the upper limit of the first wavelength region may be different from the upper limit of the second wavelength region and / or the lower limit of the first wavelength region may be different from the lower limit of the second wavelength region. That is, the upper limit of the wavelength region converted by the encapsulating layer 220 may be different from the upper limit of the wavelength region converted by the surface protective layer 210, and the lower limit of the wavelength region converted by the encapsulating layer 220 may be different from the lower limit of the wavelength region converted by the surface protective layer 210.

[0098] The wavelength converting material 215 and the wavelength converting material 225 may include at least one wavelength converting material exemplified as the wavelength converting material of the wavelength converting section 400. The wavelength converting material 215 and the wavelength converting material 225 may be the same material or different materials. In this example, the wavelength converting material 215 is a material different from the wavelength converting material 225.

[0099] The second wavelength conversion layer WL2 may emit light with a wavelength included in the excitation band of the first wavelength conversion layer WL1. This allows the light emitted by the second wavelength conversion layer WL2 to be further wavelength converted by the first wavelength conversion layer WL1. By converting the wavelength of the light incident on the photoelectric conversion device 200 in multiple steps, the wavelength conversion width can be made smaller than when the wavelength is converted in a single step, thereby improving the wavelength conversion efficiency.

[0100] The first wavelength conversion layer WL1 and the second wavelength conversion layer WL2 may each contain an inorganic phosphor or an organic phosphor. Inorganic phosphors may be more durable in stratospheric environments than organic phosphors. Inorganic phosphors may be more weather-resistant and / or more durable against ultraviolet light than organic phosphors. Therefore, using an inorganic phosphor for the wavelength conversion layer WL2 can improve the durability of the photoelectric conversion device 200. Furthermore, when the wavelength conversion layer WL2 converts light in the ultraviolet range into light with a longer wavelength than the light in the ultraviolet range, the amount of ultraviolet light to which the first wavelength conversion layer WL1 is exposed is reduced, so the first wavelength conversion layer WL1 may be made of an organic phosphor.

[0101] For example, both the wavelength converting material 215 and the wavelength converting material 225 are inorganic phosphors. The wavelength converting material 215 may be an inorganic phosphor and the wavelength converting material 225 may be an organic phosphor. Alternatively, the wavelength converting material 215 may be an organic phosphor and the wavelength converting material 225 may be an inorganic phosphor.

[0102] The maximum excitation wavelength of the first wavelength conversion layer WL1 may be different from the maximum excitation wavelength of the second wavelength conversion layer WL2. The maximum fluorescence wavelength of the first wavelength conversion layer WL1 may be different from the maximum fluorescence wavelength of the second wavelength conversion layer WL2. The first wavelength conversion layer WL1 may convert the wavelength of light that is longer than the wavelength of light that is converted by the second wavelength conversion layer WL2. For example, the wavelength conversion material 225 has an excitation band that is longer than the wavelength of the wavelength conversion material 215. Conversely, the first wavelength conversion layer WL1 may convert the wavelength of light that is shorter than the wavelength of light that is converted by the second wavelength conversion layer WL2. For example, the wavelength conversion material 225 has an excitation band that is shorter than the wavelength of the wavelength conversion material 215.

[0103] The photovoltaic conversion device 200 of this example has wavelength conversion materials in multiple physically different layers. Two or more wavelength conversion materials with different conversion properties and / or compositions may be arranged in multiple physically different layers. In this case, wavelength conversion is easier without reducing light transmittance than when all wavelength conversion materials contained in the photovoltaic conversion device 200 are added to a single layer. This also makes it easier to avoid a decrease in the light wavelength conversion effect that accompanies a decrease in light transmittance. As a result, the photovoltaic conversion device 200 of this example can efficiently convert the wavelength of light and improve power generation efficiency.

[0104] Furthermore, by using two or more wavelength converting materials, it becomes easier to convert a wider range of light wavelengths than when using a single type of wavelength converting material. For example, by using two or more wavelength converting materials, the photovoltaic conversion device 200 can increase the proportion of light in the ultraviolet region included in the incident light that is converted to light in the visible region. As a result, the power generation efficiency of the photovoltaic conversion device 200 improves, and the amount of power generated per unit mass increases.

[0105] Solar cells placed on the ground may include an encapsulation layer that protects the solar cell from oxygen and moisture, and a surface protection layer that protects the encapsulation layer from the external environment. The encapsulation layer may have a thickness of several hundred μm, and the surface protection layer may have a thickness of several mm. In contrast, according to this embodiment, the second wavelength conversion layer WL2 has a thickness of, for example, 20 μm or more and 50 μm or less. The first wavelength conversion layer WL1 has a thickness of, for example, 20 μm or more and 100 μm or less, or a thickness of less than 0.1 μm. This allows for a tensile strength of, for example, 500 g / m 2 The following photoelectric conversion device 200 can be provided. Therefore, by mounting the photoelectric conversion device 200 of this example on an aircraft 100 flying in the stratosphere, the flight distance, flight time, and / or flight latitude range of the aircraft 100 can be increased.

[0106] Here, of the one or more wavelength conversion layers WL, the wavelength conversion layer WL that is farthest from the photoelectric conversion element 300 on the light receiving surface side of the second photoelectric conversion section 322 may contain an organic phosphor. The photoelectric conversion element 300 of this example may contain an organic phosphor in the second wavelength conversion layer WL2. For example, in an aircraft 100 equipped with a low-durability element such as a perovskite-type photovoltaic element, an organic phosphor may be used as the second wavelength conversion layer WL2 because the aircraft 100 returns to the ground for maintenance to accommodate the low-durability element.

[0107] Fig. 3B shows a modified example of photoelectric conversion device 200. Photoelectric conversion device 200 of this example differs from photoelectric conversion device 200 of Fig. 3A in that it includes photoelectric conversion elements 300 with a four-terminal structure. In this example, differences from photoelectric conversion device 200 of Fig. 3A will be particularly described, and other aspects may be the same as photoelectric conversion device 200 of Fig. 3A.

[0108] The photoelectric conversion element 300 has four electrodes: a light-receiving surface electrode 310, a back surface electrode 330, a light-receiving surface electrode 312, and a back surface electrode 332. The photoelectric conversion element 300 has four terminals: a negative electrode terminal 362, a positive electrode terminal 364, a negative electrode terminal 366, and a positive electrode terminal 368. The negative electrode terminal 362, the positive electrode terminal 364, the negative electrode terminal 366, and the positive electrode terminal 368 are electrically connected to the light-receiving surface electrode 310, the back surface electrode 330, the light-receiving surface electrode 312, and the back surface electrode 332, respectively.

[0109] The light-receiving surface electrode 310 is disposed on the light-receiving surface side of the second photoelectric conversion section 322. The back surface electrode 330 is disposed on the side opposite the light-receiving surface of the second photoelectric conversion section 322. The light-receiving surface electrode 312 is disposed on the light-receiving surface side of the first photoelectric conversion section 321. The back surface electrode 332 is disposed on the side opposite the light-receiving surface of the first photoelectric conversion section 321. The light-receiving surface electrode 310, the back surface electrode 330, and the light-receiving surface electrode 312 may be transparent electrodes.

[0110] The intermediate layer 340 is disposed between the back electrode 330 and the light-receiving surface electrode 312. The intermediate layer 340 may be transparent to the wavelength absorbed by the first photoelectric conversion section 321. The intermediate layer 340 may be conductive. The intermediate layer 340 may reflect a portion of incident light to the second photoelectric conversion section 322.

[0111] In the four-terminal and three-terminal structures, current matching is not required within the photoelectric conversion element 300, but current matching may be performed in an external circuit of the photoelectric conversion element 300. Therefore, even in the four-terminal and three-terminal structures, the photoelectric conversion device 200 can simplify and reduce the size of the external circuit of the photoelectric conversion element 300 by performing current matching within the photoelectric conversion element 300. For example, the photoelectric conversion device 200 can reduce the size and weight of the power generation system 110 and / or the power control circuit 120 by reducing the size and weight of the converter coils and the like.

[0112] 3C shows a modified example of the photoelectric conversion device 200. The photoelectric conversion device 200 of this example differs from the photoelectric conversion device 200 of FIG. 2B in that the surface protection layer 210 has a plurality of wavelength conversion layers WL. In this example, differences from the photoelectric conversion device 200 of FIG. 2B will be particularly described, and other aspects may be the same as those of the photoelectric conversion device 200 of FIG. 2B. The photoelectric conversion device 200 of this example includes a photoelectric conversion element 300 with a three-terminal structure.

[0113] The surface protective layer 210 functions as the wavelength converting section 400 and has multiple wavelength conversion layers WL. In this example, the surface protective layer 210 has a wavelength converting material 215 and a wavelength converting material 217. In this example, the surface protective layer 210 has a first wavelength conversion layer WL1 containing the wavelength converting material 215 and a second wavelength conversion layer WL2 containing the wavelength converting material 217. The second wavelength conversion layer WL2 may be disposed closer to the light receiving surface than the first wavelength conversion layer WL1. In this example, the surface protective layer 210 has two wavelength conversion layers WL, but may have three or more wavelength conversion layers WL.

[0114] In one example, the second wavelength conversion layer WL2 on the light-receiving surface side of the surface protection layer 210 converts ultraviolet light into light with a longer wavelength. This reduces the amount of ultraviolet light to which layers below the second wavelength conversion layer WL2 are exposed. This improves the durability of layers below the second wavelength conversion layer WL2, such as the first wavelength conversion layer WL1.

[0115] The first wavelength conversion layer WL1 and the second wavelength conversion layer WL2 may each contain an inorganic phosphor or an organic phosphor. For example, the wavelength conversion material 215 and the wavelength conversion material 217 are both inorganic phosphors. The wavelength conversion material 217 may be an inorganic phosphor and the wavelength conversion material 215 may be an organic phosphor. Alternatively, the wavelength conversion material 217 may be an organic phosphor and the wavelength conversion material 215 may be an inorganic phosphor.

[0116] In the photoelectric conversion device 200 of this example, the surface protection layer 210 functions as the wavelength conversion section 400 , but the sealing layer 220 may also function as the wavelength conversion section 400 .

[0117] The photoelectric conversion element 300 of this example has a three-terminal structure including a negative terminal 362, a third terminal 363, and a positive terminal 364, but may also have a two-terminal structure or a four-terminal structure. The third terminal 363 is electrically connected to a third electrode 350 provided between the first photoelectric conversion section 321 and the second photoelectric conversion section 322.

[0118] The photoelectric conversion device 200 of this example can simplify and miniaturize the configuration of the external circuit of the photoelectric conversion element 300 by matching the currents of the first photoelectric conversion section 321 and the second photoelectric conversion section 322 inside the photoelectric conversion element 300. This allows the photoelectric conversion device 200 of this example to improve the amount of power generation per unit mass.

[0119] In any of the embodiments disclosed herein, the photoelectric conversion device 200 may include a light confinement structure for efficiently confining light within the photoelectric conversion device 200. For example, the photoelectric conversion device 200 has a fine uneven structure on the surface on the light incident side (sometimes referred to as the outside). The light confinement structure may be configured to confine light in a wavelength range corresponding to ultraviolet light. This allows efficient wavelength conversion of the ultraviolet light. As a result, the power generation efficiency of the photoelectric conversion device 200 is improved. The light confinement structure may be configured to confine light in a wavelength range in which the photoelectric conversion element 300 has a relatively high conversion efficiency. This improves the power generation efficiency of the photoelectric conversion device 200.

[0120] The photovoltaic device 200 may also include other layers such as a coating layer. The photovoltaic device 200 may be a monofacial solar power generation module or a bifacial solar power generation module.

[0121] 4 shows an example of the EQE characteristics of a photoelectric conversion device 200 having a two-terminal structure. The vertical axis represents EQE (%), and the horizontal axis represents wavelength (nm). EQE represents the external quantum efficiency, which is the ratio of extracted charges to the number of irradiated photons.

[0122] Graph G322w / o shows the distribution of the EQE of the second photoelectric conversion unit 322. Graph G322w shows that the EQE of the second photoelectric conversion unit 322 is increased compared to graph G322w / o by providing a wavelength conversion layer WL to convert wavelengths shorter than 400 nm into the absorption wavelength range of the second photoelectric conversion unit 322. In this example, the EQE of the second photoelectric conversion unit 322 is improved around 450 nm.

[0123] In response to an increase in the EQE in the second photoelectric conversion section 322, the photoelectric conversion device 200 may adjust the absorption wavelength range of the first photoelectric conversion section 321 and / or the second photoelectric conversion section 322 so as to maintain current consistency.

[0124] The photoelectric conversion device 200 may be adjusted so that the absorption edge E322 on the long-wavelength side of the absorption wavelength range of the second photoelectric conversion section 322 is shifted toward a shorter wavelength. The absorption edge E322 may be adjusted by changing the band gap of the second photoelectric conversion section 322. Graph G322w shows that the absorption edge E322 on the long-wavelength side is adjusted to be shifted toward a shorter wavelength side than that of graph G322w / o.

[0125] Graph G321w / o shows the distribution of the EQE of the first photoelectric conversion section 321. Graph G321w shows the distribution of the EQE of the first photoelectric conversion section 321 adjusted to match the current with that of the second photoelectric conversion section 322 when a wavelength conversion layer WL is provided.

[0126] The photoelectric conversion device 200 may adjust the absorption wavelength range of the first photoelectric conversion section 321 so that it absorbs light with a shorter wavelength. In one example, the photoelectric conversion device 200 adjusts the absorption edge E321 on the short-wavelength side of the absorption wavelength range of the first photoelectric conversion section 321 so that it shifts toward the shorter wavelength side. The absorption edge E321 may be adjusted by changing the band gap of the first photoelectric conversion section 321. Graph G321w shows that the absorption edge E321 on the shorter-wavelength side has been adjusted to shift toward the shorter wavelength side compared to graph G321w / o.

[0127] In this way, when the wavelength conversion layer WL is provided and the EQE of the second photoelectric conversion section 322 increases, the photoelectric conversion device 200 adjusts the EQE of the first photoelectric conversion section 321 to increase and to be approximately equal to the EQE of the second photoelectric conversion section 322, thereby improving current matching.

[0128] 5 shows an example of the EQE characteristics of a photoelectric conversion device 200 having another two-terminal structure. The photoelectric conversion device 200 of this example has a tandem structure in which a first photoelectric conversion section 321 and a second photoelectric conversion section 322 are stacked. The first photoelectric conversion section 321 of this example has a silicon-based photovoltaic element, and the second photoelectric conversion section 322 has a perovskite-type photovoltaic element. The photoelectric conversion device 200 of this example is provided with a wavelength conversion layer WL to convert wavelengths shorter than 400 nm into the absorption wavelength range of the second photoelectric conversion section 322.

[0129] Graph G321w shows the distribution of the EQE of the first photoelectric conversion section 321. Graph G322w shows the distribution of the EQE of the second photoelectric conversion section 322. Region R1 indicates the region where the EQE of the second photoelectric conversion section 322 is increased by converting light with wavelengths less than 400 nm into the absorption wavelength range of the second photoelectric conversion section 322 using the wavelength conversion layer WL. As described with reference to FIG. 4 , the photoelectric conversion device 200 may be adjusted so that the absorption edge E321 on the short-wavelength side of the absorption wavelength range of the first photoelectric conversion section 321 is shifted toward shorter wavelengths, and the absorption edge E322 on the long-wavelength side of the absorption wavelength range of the second photoelectric conversion section 322 is shifted toward shorter wavelengths. This allows the photoelectric conversion device 200 to improve current matching and conversion efficiency.

[0130] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0131] It should be noted that the order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and that the processes can be performed in any order unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that the processes must be performed in this order. [Explanation of symbols]

[0132] 20 Wing surface, 100 Aircraft, 110 Power generation system, 120 Power control circuit, 130 Power storage device, 140 Propulsion generating device, 142 Electric motor, 144 Propeller, 150 Sensor, 160 Control device, 200 Photoelectric conversion device, 202 Surface, 204 Back surface, 210 Surface protection layer, 215 Wavelength conversion material, 217 Wavelength conversion material, 220 Sealing layer, 225 Wavelength conversion material, 230 Back surface protection layer , 300... photoelectric conversion element, 302... front surface, 304... rear surface, 306... side surface, 310... light-receiving surface electrode, 312... light-receiving surface electrode, 320... photovoltaic element, 321... first photoelectric conversion section, 322... second photoelectric conversion section, 330... rear surface electrode, 332... rear surface electrode, 340... intermediate layer, 350... third electrode, 362... negative electrode terminal, 363... third terminal, 364... positive electrode terminal, 366... negative electrode terminal, 368... positive electrode terminal, 400... wavelength conversion section

Claims

1. a tandem photoelectric conversion element in which a first photoelectric conversion unit that converts optical energy of incident light into electrical energy and a second photoelectric conversion unit that is disposed on the light-receiving surface side of the first photoelectric conversion unit are stacked; a wavelength conversion unit disposed on the light receiving surface side of the second photoelectric conversion unit; Equipped with The wavelength converting portion includes a wavelength converting material that converts a wavelength of less than 400 nm into an absorption wavelength of the second photoelectric conversion portion. Photoelectric conversion device.

2. The wavelength conversion unit converts wavelengths of less than 400 nm into wavelengths of 400 nm or more. The photoelectric conversion device according to claim 1 .

3. The wavelength conversion unit converts the wavelength of light having a wavelength of less than 400 nm into a wavelength within the absorption wavelength range of the second photoelectric conversion unit. The photoelectric conversion device according to claim 1 .

4. The photoelectric conversion element includes at least two of a silicon-based photovoltaic element, a III-V-based photovoltaic element, a perovskite-type photovoltaic element, a CIS solar cell, a CIGS solar cell, a dye-sensitized photovoltaic element, an organic thin-film photovoltaic element, or a cuprous oxide solar cell. The photoelectric conversion device according to claim 1 .

5. The upper limit of the absorption wavelength range of the second photoelectric conversion section is lower than the upper limit of the absorption wavelength range of the first photoelectric conversion section. The photoelectric conversion device according to claim 1 .

6. The photoelectric conversion element has a two-terminal structure. The photoelectric conversion device according to claim 1 .

7. The photoelectric conversion element has a four-terminal structure or a three-terminal structure. The photoelectric conversion device according to claim 1 .

8. The wavelength conversion material includes at least one of an organic dye, a rare earth complex, an inorganic crystal or glass doped with a luminescent ion, inorganic phosphor nanoparticles, quantum dots, and oxide phosphor nanoparticles. The photoelectric conversion device according to claim 1 .

9. The wavelength converting unit is a first wavelength conversion layer disposed on at least the light receiving surface side of the second photoelectric conversion unit and configured to convert the wavelength of light in a predetermined first wavelength region; a second wavelength conversion layer disposed on the light receiving surface side of the first wavelength conversion layer and configured to convert the wavelength of light in a predetermined second wavelength region; and an upper limit value of the first wavelength range is different from an upper limit value of the second wavelength range, and / or a lower limit value of the first wavelength range is different from a lower limit value of the second wavelength range; The photoelectric conversion device according to claim 1 .

10. the first wavelength range includes a wavelength range of 100 nm or more and 400 nm or less, The second wavelength range includes a wavelength range of 100 nm or more and 400 nm or less. The photoelectric conversion device according to claim 9 .

11. the first wavelength range includes a wavelength range of 200 nm or more and 400 nm or less, The second wavelength range includes a wavelength range of 200 nm or more and 400 nm or less. The photoelectric conversion device according to claim 9 .

12. a sealing layer that seals the photoelectric conversion element; a surface protection layer disposed on the light-receiving surface side of the sealing layer; Equipped with The sealing layer and the surface protection layer function as the wavelength conversion portion. The photoelectric conversion device according to claim 1 .

13. a sealing layer that seals the photoelectric conversion element; a surface protection layer disposed on the light-receiving surface side of the sealing layer; Equipped with The surface protection layer functions as the wavelength conversion section and has a plurality of wavelength conversion layers. The photoelectric conversion device according to claim 1 .

14. The thickness of the photovoltaic element of the second photoelectric conversion portion is thinner than the thickness of the photovoltaic element of the first photoelectric conversion portion. The photoelectric conversion device according to claim 1 .

15. 15. The photoelectric conversion device according to claim 1, for use in the stratosphere.

16. The photoelectric conversion device according to any one of claims 1 to 14, a thrust generating device that generates thrust using the electrical energy generated by the photoelectric conversion device; An aircraft equipped with:

Images