JP7518658B2 - Photoelectric conversion element - Google Patents

Description

The present invention relates to a photoelectric conversion element.

In recent years, as energy demand has increased, attention has been focused on off-grid energy management in addition to energy supply from power plants. Furthermore, with the rise of mobile devices such as smartphones, an IoT society in which everything around us is connected to the Internet has been advocated, and the way energy is used is becoming more and more diverse. To realize such a society, it is important to supply electricity in unconventional ways, and there is a demand for environmental harvesting devices that extract electricity from light, heat, vibrations, etc. In particular, photovoltaic devices that use light as an energy source (power generation devices that use sunlight or indoor light) are able to obtain a relatively high output, and research, development, and commercialization are being actively conducted around the world.

Dye-sensitized solar cells (hereinafter sometimes abbreviated as "DSC"), organic thin-film solar cells (hereinafter sometimes abbreviated as "OPV"), and perovskite crystal-sensitized solar cells (hereinafter sometimes abbreviated as "PSC") are attracting attention as next-generation photovoltaic devices. DSC, OPV, and PSC are power generation devices that are unlikely to lose output even in places that are traditionally considered unsuitable for photovoltaic power generation, such as in the shade or on walls. For this reason, DSC, OPV, and PSC are expected to be used not only on the roofs of houses as in the past, but also in indoor and semi-outdoor environments.

For example, Non-Patent Document 1 reports that under 200 lux fluorescent lighting, a DSC generates more electricity than an amorphous silicon solar cell.
On the other hand, light resistance is an issue for practical use of solar cells such as DSC, OPV, and PSC. In DSC and PSC, the dye and charge transport layer are generally composed of organic materials. In OPV, the P/N semiconductor layer is generally composed of organic materials. Therefore, the above solar cells are said to have low light resistance against ultraviolet light.

Even when the solar cell is used indoors, if the solar cell is placed near a window, it is unavoidable for the solar cell to be exposed to sunlight, and therefore there is a demand for improving the light resistance of the solar cell.
In view of this, for example, Patent Document 1 proposes a DSC with excellent durability in which an ultraviolet-shielding coating is formed on the base material constituting the photoelectrode.
Moreover, Patent Document 2 proposes a DSC with excellent durability by mixing an ultraviolet absorbing material into a resin substrate.
On the other hand, Patent Documents 3 and 4 propose DSCs in which a wavelength conversion material that converts ultraviolet light into visible light is laminated on the substrate side to improve both light resistance and power generation efficiency.

Patent No. 4865171 JP 2005-346999 A JP 2001-185242 A JP 2007-265629 A

"Improving the durability of indoor dye-sensitized solar cells", Takashi Sekiguchi, Shingo Kobe, Michihiko Tani, Tomohiro Kitagaki, Koichi Takahama, Panasonic Electric Works Technical Report (Vol. 56, No. 4), pp. 87-92

However, as a result of intensive research by the present inventors, it was found that even when ultraviolet light (e.g., light having a wavelength of 400 nm or less) is blocked, when high-intensity light (e.g., 0.1 SUN or 10 mW/ ^cm2 or more) is irradiated to the DSC, the DSC deteriorates. The reason for this is not clear, but is thought to be as follows. That is, when the DSC absorbs high-intensity light, the dye changes to an oxidized state. At this time, if the electrons generated in the dye can quickly pass through the inside of the DSC and the external circuit, the dye is smoothly reduced to a neutral state. However, if the passage of the electrons is slow, for example, when the conductive base material, the semiconductor layer, the charge transport layer, and the external circuit do not have sufficient electron transport capacity, it is thought that the reduction of the dye does not proceed smoothly and the dye is decomposed or separated from the semiconductor layer.

The present invention has been made in consideration of the above circumstances, and aims to provide a photoelectric conversion element that suppresses degradation due to ultraviolet rays and high-intensity light.

The present invention has the following aspects.
[1] A photoelectric conversion element comprising: a photoelectrode having a semiconductor layer; a counter electrode facing and spaced apart from the photoelectrode; a charge transfer body positioned between the photoelectrode and the counter electrode; and a light control layer provided on the light incident surface side of the photoelectrode.
[2] The photoelectric conversion element according to [1], wherein the light control layer contains a light absorbing material.
[3] The photoelectric conversion element according to [1], wherein the light control layer contains a light reflecting material.
[4] The photoelectric conversion element according to [1], wherein the light control layer contains a light diffusing material.
[5] The photoelectric conversion element according to [1], wherein the light control layer contains a photochromic material.
[6] The photoelectric conversion element according to [5], wherein the photochromic material has a light absorption peak in a region of 400 nm or less in a decolorized state and a light absorption peak in a region of 400 nm or more in a colored state.
[7] The photoelectric conversion element according to [1], wherein the light control layer contains an electrochromic material.
[8] The photoelectric conversion element according to [7], wherein the electrochromic material has a light absorption peak in a region of 400 nm or less in a decolorized state and a light absorption peak in a region of 400 nm or more in a colored state.
[9] The photoelectric conversion element according to [1], wherein the light control layer contains a thermochromic material.
[10] The photoelectric conversion element according to [9], wherein the thermochromic material has a light absorption peak in a region of 400 nm or less in a decolorized state and a light absorption peak in a region of 400 nm or more in a colored state.
[11] The photoelectric conversion element according to any one of [1] to [10], which is an organic solar cell or a solar cell having a perovskite crystal.

The present invention provides a photoelectric conversion element that suppresses degradation due to ultraviolet light and high-intensity light.

1 is a cross-sectional view of a photoelectric conversion element according to one embodiment of the present invention. 1 is a schematic diagram of a manufacturing apparatus for a photoelectric conversion element according to an embodiment of the present invention.

The following describes an embodiment of the photoelectric conversion element according to the present invention with reference to the drawings. Note that the drawings used in the following description show enlarged views of characteristic parts for the sake of convenience, and the dimensional ratios of each component may differ from the actual ones. Furthermore, the materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited to them, and may be modified as appropriate without departing from the spirit of the invention.

[Photoelectric conversion element]
As shown in FIG. 1, a photoelectric conversion element 1 to which the present invention is applied has a photoelectrode 10 , a counter electrode 20 , a charge transfer body 30 , a sealing material 40 , a conductive material 50 , and a light control layer 60 .
The photoelectrode 10 and the counter electrode 20 face each other with a gap therebetween.
The charge transfer body 30 is located between the photoelectrode 10 and the counter electrode 20 .
The sealing material 40 is located between the photoelectrode 10 and the counter electrode 20 to seal the charge transfer body 30 .
The charge transfer body 30 exists in a region surrounded by the photoelectrode 10, the counter electrode 20, and the sealing material 40. The charge transfer body 30 contacts both the photoelectrode 10 and the counter electrode 20.
The conductive material 50 is located between the photoelectrode 10 and the counter electrode 20 and enables electrical continuity between the photoelectrode 10 and the counter electrode 20 .
The light control layer 60 is provided on the light incident surface 10 a side of the photoelectrode 10 (the surface opposite to the counter electrode 20 ).

In the photoelectric conversion element 1 of this embodiment, the light control layer 60 includes a light absorbing material, a light reflecting material, a light diffusing material, a photochromic material, an electrochromic material, or a thermochromic material.
The light control layer 60 is preferably formed from a material having a wavelength range with a transmittance of 90% or less in the emission wavelength range of sunlight or white light emitting diodes, fluorescent lamps, etc. (e.g., a wavelength range of 400 nm to 800 nm), more preferably formed from a material having a wavelength range with a transmittance of 70% or less, even more preferably formed from a material having a wavelength range with a transmittance of 50% or less, and most preferably formed from a material having a wavelength range with a transmittance of 20% or less.

When the light control layer 60 includes a light absorbing material, the light control layer 60 is composed of only the light absorbing material, or the light control layer 60 includes the light absorbing material as part of its constituent members. When the light control layer 60 includes a light absorbing material, the light control layer 60 functions as a light-reducing layer that reduces the amount of light incident on the light incident surface 10a of the photoelectrode 10. In other words, the light control layer 60 absorbs light that is about to be incident on the light incident surface 10a of the photoelectrode 10, thereby reducing the amount of light that is incident on the light incident surface 10a of the photoelectrode 10.

The light absorbing material is not particularly limited, but examples thereof include a light absorbing type neutral density (ND) filter for adjusting the amount of light, and an optical filter.
Examples of light-absorbing ND filters include filters having a resin substrate such as polyethylene terephthalate or a glass substrate to which a light-absorbing material has been added, and filters having multiple layers of dielectric films or metal films formed on the substrate.
Examples of optical filters include filters in which a light-absorbing material (functional dye) is added to a resin substrate such as polyethylene terephthalate or a glass substrate, filters in which a film made of a light-absorbing material (functional dye) is formed on the substrate, etc. Examples of functional dyes include coumarin derivatives, phthalocyanine derivatives, porphyrin derivatives, perylene derivatives, cyanine derivatives, and squarium derivatives.

When the light control layer 60 includes a light reflecting material, the light control layer 60 is composed of only the light reflecting material, or the light control layer 60 includes the light reflecting material as part of its constituent members. When the light control layer 60 includes a light reflecting material, the light control layer 60 functions as a light-reducing layer.

The light reflecting material is not particularly limited, but examples thereof include a light reflecting type neutral density (ND) filter for adjusting the amount of light, and a reflective film.
Examples of light reflection type ND filters include filters in which a metal film is formed on a resin substrate such as polyethylene terephthalate or a glass substrate. Examples of materials for the metal film include metals with a large refractive index. Examples of such metals include nickel, chromium, aluminum, gold, silver, and copper.
Examples of the reflective film include filters in which fine particles with a high refractive index are added to a resin substrate such as polyethylene terephthalate or a glass substrate. Materials for the fine particles are not particularly limited, but examples include inorganic fine particles such as silicon oxide and titanium oxide, and organic fine particles made of acrylic resin, etc., from the viewpoint of refractive index. The particle diameter of the fine particles is not particularly limited, but is preferably 400 nm or more, for example, from the viewpoint of effectively reflecting light.

When the light control layer 60 includes a light diffusing material, the light control layer 60 is composed of only a light diffusing material, or the light control layer 60 includes a light diffusing material as part of its constituent members. When the light control layer 60 includes a light diffusing material, the light control layer 60 functions as a light-reducing layer.

Examples of light diffusing materials include light diffusing films, light diffusing glass, light diffusing curtains, light diffusing paper screens, and mesh screen doors.
Examples of the light diffusion film include a resin substrate such as polyethylene terephthalate, or a film in which fine particles with a high refractive index are added to a glass substrate. The material of the fine particles is not particularly limited, but from the viewpoint of refractive index, for example, inorganic fine particles such as silicon oxide or titanium oxide, or organic fine particles made of acrylic resin, etc. are included. The particle diameter of the fine particles is not particularly limited, but from the viewpoint of effective reflection of light, for example, it is preferably 400 nm or more.
Examples of light-diffusing glass include ground glass, frosted glass, and figured glass.

When the light control layer 60 contains a photochromic material, the light control layer 60 is composed of only the photochromic material, or the light control layer 60 contains the photochromic material as part of its constituent members. When the light control layer 60 contains a photochromic material, the light control layer 60 functions as a dimming layer that adjusts the wavelength of light incident on the light incident surface 10a of the photoelectrode 10. In other words, the light control layer 60 changes color when struck by light that is about to enter the light incident surface 10a of the photoelectrode 10, and selects the wavelength of light that is incident on the light incident surface 10a of the photoelectrode 10.

Examples of photochromic materials include a resin substrate such as polyethylene terephthalate or a glass substrate to which a photochromic material is added, and a film of a photochromic material formed on a resin substrate such as polyethylene terephthalate or a glass substrate.
Examples of photochromic materials include inorganic materials and organic materials (pigments).
Examples of inorganic materials include silver halide and tungsten oxide.
Examples of organic materials include T-type dyes (dyes whose color change process occurs not only by light but also by heat) and P-type dyes (dyes whose color change process occurs only by light). Examples of T-type dyes include azobenzene derivatives, spiropyran derivatives, and spirooxazine derivatives. Examples of P-type dyes include diarylethene derivatives.
For example, the photochromic material preferably has a light absorption peak in the region of 400 nm or less in the decolorized state, and a light absorption peak in the region of 400 nm or more in the colored state. When the photochromic material changes from the colored state to the decolorized state, it is more preferable that the absorption edge of the light absorption peak is 1000 nm or less. The photochromic material changes from the colored state to the decolorized state by absorbing light of 400 nm or less. The change from the colored state to the decolorized state occurs when the photochromic material absorbs light of 400 nm or more, or in the case of a T-type dye, the colored state to the decolorized state is also changed by heat.

When the light control layer 60 contains an electrochromic material, the light control layer 60 is composed only of the electrochromic material, or the light control layer 60 contains the electrochromic material as part of its constituent members. When the light control layer 60 contains an electrochromic material, the light control layer 60 functions as a dimming layer.

Examples of electrochromic materials include a resin substrate such as polyethylene terephthalate or a glass substrate to which an electrochromic material is added, and a film of an electrochromic material formed on a resin substrate such as polyethylene terephthalate or a glass substrate.
Examples of electrochromic materials include inorganic materials and organic materials.
Examples of inorganic materials include oxide semiconductors such as molybdenum oxide and tungsten oxide.
Examples of organic materials include viologen derivatives, polythiophene derivatives, polyaniline derivatives, and polypyrrole derivatives.
For example, the electrochromic material preferably has a light absorption peak in a region of 400 nm or less in a decolorized state and a light absorption peak in a region of 400 nm or more in a colored state. When the electrochromic material is in a colored state, the absorption edge of the light absorption peak is more preferably 1000 nm or less. The electrochromic material changes from a decolorized state to a colored state by applying a voltage from the outside and causing an oxidation reaction or a reduction reaction. The electrochromic material also changes from a colored state to a decolorized state by applying a voltage from the outside and causing a reduction reaction or an oxidation reaction.
In this embodiment, as the external voltage, electricity generated by the photoelectric conversion element 1 may be directly used, or electricity generated by the photoelectric conversion element 1 may be temporarily stored in a storage battery and used. Also, electricity obtained from a backup battery such as a primary battery may be used.

When the light control layer 60 contains a thermochromic material, the light control layer 60 is composed only of a thermochromic material, or the light control layer 60 contains a thermochromic material as part of its constituent members. When the light control layer 60 contains a thermochromic material, the light control layer 60 functions as a light control layer.

Examples of thermochromic materials include a resin substrate such as polyethylene terephthalate or a glass substrate to which a thermochromic material is added, and a resin substrate such as polyethylene terephthalate or a glass substrate to which a film made of a thermochromic material is formed.
Examples of thermochromic materials include liquid crystal materials and dye-based materials.
Examples of the liquid crystal material include cholesterol derivatives and cyanobiphenyls.
The dye-based material may be, for example, a leuco dye.
The thermochromic material preferably has a light absorption peak in the region of 400 nm or less in the decolorized state and a light absorption peak in the region of 400 nm or more in the colored state. When the thermochromic material is in the colored state, the absorption edge of the light absorption peak is more preferably 1000 nm or less.
The thermochromic material changes from a decolorized state to a colored state when, for example, the temperature of the light control layer 60 becomes 50° C. or higher under irradiation with sunlight. Also, when the temperature of the light control layer 60 becomes 50° C. or lower in an environment where no sunlight is irradiated, the thermochromic material changes from a colored state to a decolorized state.

The thickness of the light control layer 60 is adjusted as appropriate depending on the configuration of the light control layer 60, but is preferably, for example, 50 μm or more and 50 mm or less.

The intensity of the light transmitted through the light control layer 60 is preferably 90 mW/ ^cm2 or less, more preferably 70 mW/ ^cm2 or less, even more preferably 50 mW/ ^cm2 or less, and most preferably ²⁰ mW/cm2 or less. The intensity of the light transmitted through the light control layer 60 is preferably 0.01 mW/ ^cm2 or more, and more preferably 0.04 mW/ ^cm2 or more.
If the intensity of the light transmitted through the light control layer 60 is 90 mW/ ^cm2 or less, deterioration due to ultraviolet rays and high-intensity light can be suppressed, and the amount of power generated by the photoelectric conversion element 1 can be maintained for a long period of time.
If the intensity of the light passing through the light control layer 60 is 0.01 mW/cm ² or more, the photoelectric conversion element 1 can generate electricity for driving a device such as a sensor.

The photoelectrode 10 includes a photoelectrode support 12 , a photoelectrode conductive layer 14 , and an inorganic semiconductor layer 16 .
In a plane parallel to the surface of the photoelectrode support 12, the direction in which the conductive material 50 extends is defined as a P1 direction, and the direction perpendicular to the P1 direction is defined as a P2 direction.

The photoelectrode conductive layer 14 is located on the photoelectrode support 12. The inorganic semiconductor layer 16 is located on the photoelectrode conductive layer 14. That is, the photoelectrode support 12, the photoelectrode conductive layer 14, and the inorganic semiconductor layer 16 are located in this order.
The inorganic semiconductor layer 16 is in contact with the charge transfer body 30. The inorganic semiconductor layer 16 covers a part of the photoelectrode conductive layer 14. Outside the inorganic semiconductor layer 16, a part of the photoelectrode conductive layer 14 is in contact with the charge transfer body 30. The inorganic semiconductor layer 16 carries a sensitizing dye.
In addition, in the region where the charge transfer body 30 is present, the inorganic semiconductor layer 16 may cover the entire surface of the photoelectrode conductive layer 14 .

The photoelectrode support 12 is optically transparent. The photoelectrode support 12 is a glass plate, a resin plate, a film or a sheet (resin plates, films and sheets are sometimes collectively referred to as resin plates, etc.), etc.

When the photoelectrode support 12 is a glass plate, the material is soda-lime glass, quartz glass, borosilicate glass, Vycor glass, alkali-free glass, blue plate glass, white plate glass, etc.

When the photoelectrode support 12 is a resin plate or the like, the material is polyacrylic, polycarbonate, polyester, polyimide, polystyrene, polyvinyl chloride, polyamide, etc.

The light control layer 60 may also serve as the photoelectrode support 12. For example, frosted glass may be used as the light control layer 60, and an indium tin oxide (ITO) film or the like may be formed on one surface of the glass as the photoelectrode conductive layer 14. The light control layer 60 may be placed on the photoelectrode support 12 via a transparent adhesive layer (OCA, etc.), or may be formed directly on the photoelectrode support 12 by a method such as coating or vapor deposition. The light control layer 60 and the photoelectrode support 12 may be spaced apart. The distance between them is not particularly limited, but can be set arbitrarily, for example, within the range of 0.1 cm to 10 cm.

The photoelectrode conductive layer 14 is present over the entire surface of the photoelectrode support 12 on the counter electrode 20 side.
The photoelectrode conductive layer 14 is not particularly limited as long as it has conductivity. The photoelectrode conductive layer 14 is a conventionally known conductive layer for dye-sensitized solar cells. When the photoelectrode 10 forms the light incident surface, the photoelectrode conductive layer 14 has light transparency. That is, the photoelectrode conductive layer 14 is preferably a so-called transparent conductive layer.
Examples of materials for the photoelectrode conductive layer 14 include metals such as gold, platinum, silver, copper, chromium, tungsten, aluminum, magnesium, titanium, nickel, manganese, zinc, iron, and alloys thereof; conductive transparent inorganic materials such as fluorine-doped tin oxide (FTO), sodium, sodium-potassium alloy, lithium, magnesium, aluminum, magnesium-silver mixture, magnesium-indium mixture, aluminum-lithium alloy, Al/Al ₂ O ₃ mixture, Al/LiF mixture, CuI, indium tin oxide (ITO), SnO ₂ , aluminum zinc oxide (AZO), indium zinc oxide (IZO), and gallium zinc oxide (GZO); conductive transparent polymers, etc. These materials may be used alone or in combination of two or more.

The thickness of the photoelectrode conductive layer 14 is appropriately determined depending on the material constituting the photoelectrode conductive layer 14. When the photoelectrode conductive layer 14 is a metal, the thickness of the photoelectrode conductive layer 14 is preferably 10 nm or more and 50 nm or less. When the photoelectrode conductive layer 14 is a conductive transparent inorganic material or a conductive transparent polymer, the thickness of the photoelectrode conductive layer 14 is preferably 50 nm or more and 500 μm or less.
The thickness of the photoelectrode conductive layer 14 is the average value of measurements taken at any ten points in an image of a cross section perpendicular to the surface of the photoelectrode support 12 .

The inorganic semiconductor layer 16 may be made of any semiconductor material that is capable of adsorbing a sensitizing dye.
Examples of the semiconductor material include oxides such as titanium oxide, zinc oxide, indium oxide, tin oxide, and gallium oxide; oxides such as tin sulfide, indium sulfide, zinc sulfide, cuprous oxide, molybdenum trioxide, vanadium pentaoxide, and tungsten oxide; copper(I) thiocyanate, copper iodide, molybdenum disulfide, molybdenum diselenide, and copper(I) sulfide.
The inorganic semiconductor layer 16 may be a dense layer or a porous layer. From the viewpoint of further improving the photoelectric conversion efficiency of the photoelectric conversion element 1, the inorganic semiconductor layer 16 is preferably a porous layer.
The thickness of the inorganic semiconductor layer 16 is preferably 500 nm or more and 100 μm or less. The thickness of the inorganic semiconductor layer 16 is the average value of measurements at any ten points in an image of a cross section perpendicular to the surface of the photoelectrode support 12.

The sensitizing dye is composed of an organic dye or a metal complex dye. Examples of organic dyes include various organic dyes such as coumarin-based, polyene-based, cyanine-based, hemicyanine-based, and thiophene-based dyes. Examples of metal complex dyes include ruthenium complexes.

The counter electrode 20 has a counter electrode support 22 and a counter electrode conductive layer 24. The counter electrode conductive layer 24 is located on the counter electrode support 22.
The photoelectrode 10 and the counter electrode 20 face each other with the inorganic semiconductor layer 16 and the counter electrode conductive layer 24 facing each other.

The counter electrode support 22 is a glass plate, a resin plate, a film or a sheet (resin plates, films and sheets are sometimes collectively referred to as resin plates, etc.), etc.

When the counter electrode support 22 is a glass plate, the material is soda-lime glass, quartz glass, borosilicate glass, Vycor glass, alkali-free glass, blue plate glass, white plate glass, etc.

When the counter electrode support 22 is a resin plate or the like, the material is polyacrylic, polycarbonate, polyester, polyimide, polystyrene, polyvinyl chloride, polyamide, etc.

The material of the counter electrode conductive layer 24 is, like the material of the photoelectrode conductive layer 14, a metal, a conductive transparent inorganic material, a conductive transparent polymer, or the like. The counter electrode conductive layer 24 and the photoelectrode conductive layer 14 may be the same or different. When the counter electrode 20 forms the light incidence surface, the counter electrode conductive layer 24 has light transparency. In this case, the counter electrode conductive layer 24 is preferably a so-called transparent conductive layer.
The preferred thickness of counter electrode conductive layer 24 is similar to the preferred thickness of photoelectrode conductive layer 14. The thickness of counter electrode conductive layer 24 may be the same as or different from the thickness of photoelectrode conductive layer 14.

A catalyst layer 26 may be located on the counter electrode conductive layer 24. A plurality of catalyst layers 26 are provided spaced apart from each other on the surface of the counter electrode conductive layer 24 facing the photoelectrode 10. The catalyst layer 26 is in contact with the charge transfer body 30. Outside the catalyst layer 26, a portion of the counter electrode conductive layer 24 is in contact with the charge transfer body 30.
Examples of materials for the catalyst layer 26 include PEDOT, platinum, ITO, polyaniline, and carbon.
The thickness of the catalyst layer 26 is preferably 2 nm to 500 μm. The thickness of the catalyst layer 26 is the average value of measurements at any ten points in an image of a cross section perpendicular to the surface of the photoelectrode support 12.

The charge transfer body 30 is an electrolytic solution or a gel electrolyte, or a solid P-type semiconductor. The charge transfer body 30 contacts the inorganic semiconductor layer 16, the photoelectrode conductive layer 14, the catalyst layer 26, and the counter electrode conductive layer 24. The charge transfer body 30 has a redox pair capable of supplying electrons to the sensitizing dye.
The electrolyte has a dispersion medium (hereinafter sometimes referred to as "electrolyte dispersion medium") and a redox pair dispersed in the electrolyte dispersion medium. A gel electrolyte is an electrolyte made into a gel state. A method for producing a gel electrolyte is, for example, to add a gelling agent or a thickener to the electrolyte to make it into a gel state. The charge transfer body 30 of the gel electrolyte can increase the durability of the photoelectric conversion element 1.

The electrolyte dispersion medium is a non-aqueous solvent, an ionic liquid, etc. The non-aqueous solvent is acetonitrile, propionitrile, etc. The ionic liquid is dimethylpropylimidazolium iodide, butylmethylimidazolium iodide, etc.
A redox couple is a combination of a supporting electrolyte and a halogen molecule.
The supporting electrolyte is an iodide such as a metal iodide, such as lithium iodide, sodium iodide, or potassium iodide; an iodide salt such as tetraalkylammonium iodide, pyridinium iodide, or imidazolium iodide; or a bromine compound such as a metal bromide, such as sodium bromide, or potassium bromide; or a bromine salt such as tetraalkylammonium bromide, pyridinium bromide, or imidazolium bromide.
The halogen molecules include iodine molecules, bromine molecules, and the like.
As a combination of a supporting electrolyte and a halogen molecule, a combination of an iodide and an iodine molecule, and a combination of a bromine compound and a bromine molecule are preferable.

Examples of solid-state hole P-type semiconductors include inorganic semiconductors such as copper iodide and copper sulfide, and organic semiconductors such as spiro-OMeTAD and polythiophene derivatives.

The sealant 40 is located between the photoelectrode 10 and the counter electrode 20. Both ends of the sealant 40 in the thickness direction are bonded to the photoelectrode 10 and the counter electrode 20, respectively. The sealant 40 seals the charge transfer body 30.
In this embodiment, both ends of the sealing material 40 in the thickness direction are joined to the photoelectrode conductive layer 14 and the counter electrode conductive layer 24, respectively.
The sealing material 40 may be any sealing material capable of sealing the charge transfer body 30, and may be a conventionally known sealing material such as a photocurable resin or a thermosetting resin.
The thickness of the sealing material 40 is preferably 10 μm or more and 200 μm or less. The thickness of the sealing material 40 is the average value of measurements at any ten points in an image of a cross section perpendicular to the surface of the photoelectrode support 12.

The conductive material 50 is located between the photoelectrode 10 and the counter electrode 20. The conductive material 50 contacts both the photoelectrode 10 and the counter electrode 20. The sealing material 40 is located between the conductive material 50 and the charge transfer body 30. In the P2 direction, both sides of the conductive material 50 are adjacent to the sealing material 40. It is preferable that the conductive material 50 and the sealing material 40 contact each other.
The conductive material 50 contains conductive particles and an adhesive.

The conductive particles may be particles that are themselves conductive, such as metal particles, or may be composite particles whose surface layer is a conductive metal layer.
Specific examples include metal particles made of metals such as gold, silver, copper, chromium, titanium, platinum, nickel, tin, zinc, lead, tungsten, iron, and aluminum; particles made of compounds containing these metals; particles made of conductive resins; carbon-based particles such as carbon black; and composite particles such as particles made of resin particles coated with a conductive metal such as electroless nickel can also be used.
The shape of the conductive particles is not particularly limited as long as it serves as the spacer. Examples of the shape include spherical, elliptical, cubic, and polygonal shapes. From the viewpoint of having the largest encapsulation volume and low resistance, the conductive particles are preferably spherical.
The average particle size of the conductive particles is preferably 5 μm or more and 500 μm or less, and more preferably 10 μm or more and 500 μm or less.
The average particle size of the conductive particles is the average of the measurements of any 10 particles in the image of the conductive material. If the conductive particles are not spherical, the area of the conductive particles in the image of the conductive material is measured, and the diameter of a circle having the same area is taken as the diameter of the conductive particle to calculate the average of the 10 particles.

Examples of the adhesive include a resin material containing at least one of a thermoplastic resin, a thermosetting resin, and an ultraviolet-curable resin, or a cured product thereof. The adhesive may be the same material as the sealing material 40.
Examples of the resin material include vinyl acetate resin emulsion adhesives, ethylene-vinyl acetate copolymer resins, EVA (ethylene-vinyl acetate-vinyl chloride terpolymer) emulsion adhesives, α-olefin (isobutene-maleic anhydride resin) adhesives, acrylic resin emulsion adhesives, styrene-butadiene rubber latex adhesives, vinyl acetate resin solvent adhesives, acrylic resin solvent adhesives, vinyl chloride resin solvent adhesives, chloroprene rubber solvent adhesives, chloroprene rubber solvent mastic adhesives, nitrile rubber solvent adhesives, recycled rubber solvent styrene-butadiene rubber (SBR) solvent adhesives, urethane resin adhesives, silicone resin adhesives, modified silicone resin adhesives, epoxy-modified silicone resin adhesives, acrylic resin (second generation of acrylic Examples of adhesives include SGA (Sodium GaAs) adhesives, starch-based adhesives, polymer cement mortar, epoxy resin mortar, silylated urethane resin-based adhesives, and hot melt adhesives.

In addition, as described above, a highly viscous adhesive can be used as the adhesive, so long as it has the function of maintaining the electrodes facing each other with a predetermined distance between them. Examples of highly viscous adhesives include, but are not limited to, rubber-based, acrylic-based, silicone-based, and urethane-based adhesives. Specific examples include natural rubber, acrylic acid ester copolymers, silicone rubber, and urethane resins.

The conductive material 50 may contain an auxiliary conductive material in addition to the conductive particles and adhesive. The auxiliary conductive material is a small-diameter material that does not act as a spacer between the photoelectrode 10 and the counter electrode 20. When the auxiliary conductive material is present in the gaps between the conductive particles, conduction between the electrodes is more easily achieved.
The auxiliary conductive material may be any material that is conductive and does not impair the conductivity of the conductive particles, and may be in the form of particles or fibers having a smaller diameter than the conductive particles.
Examples of materials for the auxiliary conductive substance include metals such as gold, silver, copper, chromium, titanium, platinum, nickel, tin, zinc, lead, tungsten, iron, and aluminum, compounds containing these metals, conductive resins, and carbon materials such as carbon black. The auxiliary conductive substance may be made of the same material as the conductive particles.
When the auxiliary conductive material is particulate, the average particle size is preferably 80% or less of the average particle size of the conductive particles, more preferably 50% or less, and even more preferably 30% or less, in that the auxiliary conductive material is likely to exist in the gaps between the conductive particles.
The method for measuring the average particle size of the auxiliary conductive material is the same as the method for measuring the average particle size of the conductive particles.
When the auxiliary conductive material is a conductive fiber, the average fiber diameter is preferably 45% or less, more preferably 30% or less, and even more preferably 15% or less of the average particle diameter of the conductive particles.
The fiber length of the conductive fibers is preferably adjusted appropriately so as not to impair the conductivity of the conductive particles. For example, the average aspect ratio, expressed as fiber length/fiber diameter, is preferably 2 or more and 500 or less.
The average fiber diameter of the auxiliary conductive material is the average value of 10 arbitrary measured values in the image of the conductive material.

The conductive paste containing the conductive particles, adhesive, and optionally an auxiliary conductive material is solidified to form the conductive material 50. The conductive paste may contain an auxiliary medium to maintain the dispersion state of the conductive particles and adhesive, as necessary. Examples of the auxiliary medium include, but are not limited to, water, ester-based solvents (e.g., ethyl acetate), alcohol-based solvents, ketone-based solvents, ester-based solvents (e.g., tetrahydrofuran), hydrocarbon-based solvents (e.g., hexane), and aromatic solvents.

In FIG. 1 , which shows the photoelectric conversion element 1 in a plan view, a first insulating portion (insulating portion) or a second insulating portion (insulating portion) having a generally strip-like shape is present in the region where the photoelectrode conductive layer 14, the counter electrode conductive layer 24, and the sealing material 40 overlap.
The first insulating portion is a cut portion that penetrates the photoelectrode conductive layer 14. The first insulating portion divides the photoelectrode conductive layer 14 and electrically insulates it.
The second insulating portion is a cut portion that penetrates the counter electrode conductive layer 24. The second insulating portion divides the counter electrode conductive layer 24 and electrically insulates it.
In the P2 direction, the first insulating portions and the second insulating portions are alternately present.

The photoelectric conversion element 1 having such a configuration is preferably an organic solar cell or a solar cell having perovskite crystals.

According to the photoelectric conversion element 1 of this embodiment, by providing a light control layer 60 on the light incident surface 10a side of the photoelectrode 10, it is possible to reduce the amount of light incident on the light incident surface 10a of the photoelectrode 10 and adjust the wavelength of the light incident on the light incident surface 10a of the photoelectrode 10, thereby suppressing deterioration due to ultraviolet rays and high-intensity light. Therefore, the photoelectric conversion element 1 of this embodiment can maintain the amount of power generation for a long period of time.

[Method of manufacturing photoelectric conversion element]
The photoelectric conversion element of this embodiment can be manufactured, for example, by the following method.
The method for manufacturing the photoelectric conversion element of this embodiment is a method for continuously manufacturing the photoelectric conversion element 1 having the configuration shown in Fig. 1 by providing a sealant 40, a conductive material 50 and a charge transfer body 30 on the photoelectrode 10 while transporting the photoelectrode 10 in the P1 direction using a manufacturing apparatus 100 illustrated in Fig. 2, and bonding the photoelectrode 10 and the counter electrode 20 while transporting the counter electrode 20 in the P1 direction. The conductive material 50 is formed, for example, by applying a conductive paste.

First, using an apparatus employing a roll-to-roll system (not shown), the photoelectrode support 12 is continuously transported in a predetermined direction while the photoelectrode conductive layer 14 is formed on the surface of the photoelectrode support 12 by a known sputtering method, printing method, or the like. Next, the inorganic semiconductor layer 16 is formed at a predetermined position of the photoelectrode conductive layer 14 by a known aerosol deposition method (AD method). Next, a sensitizing dye is adsorbed to the inorganic semiconductor layer 16 by a known method to obtain the photoelectrode 10. The photoelectrode 10 is wound into a roll with the inorganic semiconductor layer 16 facing outward.
After the photoelectrode conductive layer 14 is formed, the photoelectrode conductive layer 14 may be temporarily wound into a roll before the inorganic semiconductor layer 16 is formed. Alternatively, after the photoelectrode 10 is formed, the next step may be carried out without being wound.

Separately, using an apparatus employing a roll-to-roll system (not shown), the counter electrode support 22 is continuously transported in a predetermined direction while the counter electrode conductive layer 24 is formed on the surface of the counter electrode support 22 by a known sputtering method, printing method, or the like. Next, a catalyst layer 26 is formed at a predetermined position on the counter electrode conductive layer 24 by a known sputtering method, printing method, or the like to obtain the counter electrode 20. The counter electrode 20 is wound into a roll with the catalyst layer 26 facing inward.
After the counter electrode conductive layer 24 is formed, the electrode may be temporarily wound into a roll before the catalyst layer 26 is formed. Alternatively, after the counter electrode 20 is formed, the electrode may be subjected to the next step without being wound.

Next, as shown in FIG. 2, the roll-shaped photoelectrode 10 and the counter electrode 20 are placed in the manufacturing apparatus 100 .
While the photoelectrode 10 is being fed and transported in the P3 direction, a first insulating portion (not shown) is formed using an insulating portion forming device (not shown). Examples of the insulating portion forming device include a processing device equipped with a die-cut roll and a laser processing device.

Next, a sealing material is applied to the photoelectrode 10 during transportation using a sealing material application device 101 to form an uncured sealing material 40 .
Next, a conductive paste is applied using a conductive material application device 102 to form an uncured conductive material 50. Next, an electrolyte is applied using an electrolyte application device 103 to form a charge transfer body 30.

Meanwhile, while the counter electrode 20 is being fed and transported in the P4 direction, a second insulating portion (not shown) is formed using an insulating portion forming device (not shown). The insulating portion forming device is the same as described above.

Next, the photoelectrode 10 on which the charge transfer body 30 has been formed and the counter electrode 20 on which the second insulating portion has been formed are introduced in an overlapping state between a pair of pressing rolls 111 and 112. The pressing rolls 111 and 112 press the photoelectrode 10 and the counter electrode 20 passing between them against each other.
Next, immediately after passing through the pressing rolls 111 and 112, the uncured sealing material 40 and conductive material 50 are cured using a curing device (not shown), and the sealing material 40 and conductive material 50 are bonded to the photoelectrode 10, and the sealing material 40 and conductive material 50 are bonded to the counter electrode 20. For example, when the uncured sealing material 40 is a photocurable resin, the sealing material 40 is cured by irradiating ultraviolet rays using a UV lamp as a curing device. When the uncured conductive material 50 is a thermosetting resin, the conductive material 50 is cured by heating. In this way, the photoelectrode 10 and the counter electrode 20 are bonded to each other via the sealing material 40 and conductive material 50.

Next, a fusion portion forming device including an ultrasonic application unit 115 that applies ultrasonic vibrations and a base 116 facing the ultrasonic application unit 115 is used to form a fusion portion at a predetermined position.
The tip of the ultrasonic wave application part 115 and the tip of the base 116 each have a plurality of projections and recesses. The projections and recesses of both have shapes that mesh with each other. The distance between the ultrasonic wave application part 115 and the base 116 is variable.
The tip of the ultrasonic wave applying part 115 and the tip of the base 116 are brought into contact with the laminated counter electrode 20 and photoelectrode 10, respectively, to reduce the distance between the ultrasonic wave applying part 115 and the base 116. When pressure is applied while ultrasonic vibration is applied in this manner, vibration energy is transmitted to structures such as the photoelectrode support 12, the counter electrode support 22, and the sealant 40 present between them, generating frictional heat, and structures with low melting points melt and flow. In addition, if a rigid body such as a metal is present in the structure, the rigid body is destroyed by the ultrasonic vibration, and if the particle size of the destroyed particles is relatively small, it will diffuse (move).
As a result, structures such as the sealant 40 that were present between the photoelectrode support 12 and the counter electrode support 22 are pushed out to the area adjacent to the fused portion, forming a fused portion where the photoelectrode support 12 and the counter electrode support 22 are fused together.

Next, the light control layer 60 is provided by bonding the light control layer 60 to the light incident surface 10a of the photoelectrode 10 via a transparent adhesive layer.

The photoelectric conversion element 1 can be manufactured through the above steps. After this, the long photoelectric conversion element 1 can be cut along the length direction (P2 direction) of the fused portion so as to separate one fused portion, and a photoelectric conversion element of the size actually used can be cut out.

The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Example 1]
(Fabrication of photoelectric conversion element)
Using the materials shown below, a photoelectric conversion element shown in FIG. 1 was produced according to the method for producing a photoelectric conversion element shown in the above embodiment.
Photoelectrode support and counterelectrode support: material PEN.
Photoelectrode conductive layer and counterelectrode conductive layer: material ITO.
Inorganic semiconductor layer: a porous layer (film thickness 10 μm) made of titanium oxide (primary particle diameter 15 nm).
Sensitizing dye: Ruthenium-based dye (commonly known as N719).
Catalyst layer: platinum (film thickness 10 nm).
・Charge transfer body: Electrolyte.
・Encapsulant: UV curable resin.
Conductive paste: A mixture of adhesive (ultraviolet-curable resin) and conductive particles (Micropearl (registered trademark) AU-250 with gold-plated surface).
Light control layer: ND filter (absorption type ND filter manufactured by HOYA, optical density OD=0.3, thickness 2.5 mm, transmittance 50%).

(Lightfastness Evaluation)
The initial power generation amount of the photoelectric conversion element was measured under 200 lux, and then the element was stored for 500 hours in a 1SUN light resistance tester (xenon accelerated weather resistance tester, product name: Q-SUN Xe-3, manufactured by Sanyo Trading Co., Ltd.).
After 500 hours had elapsed, the amount of power generated by the photoelectric conversion element was measured again under 200 Lux.
The amount of electricity generated by the photoelectric conversion element was measured as follows.
The photoelectric conversion element was adjusted to be irradiated with 200 Lux of light using a surface-emitting white LED device and a colorimeter: CL-200A (manufactured by Konica Minolta Japan, Inc.) Under light irradiation, a voltage was applied to the photoelectric conversion element using a source meter (manufactured by Keithley Instruments, Inc.), and the amount of power generation was calculated from the amount of current generated.
The results are shown in Table 1.

[Example 2]
The photoelectric conversion element of Example 2 was prepared in the same manner as in Example 1, except that a light-reflecting ND filter (product name: ND204B, manufactured by Thorlabs, optical density OD = 0.4, thickness 2.5 mm, transmittance 40%) was used as the light control layer.
The light resistance of the obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 3]
A photoelectric conversion element of Example 3 was produced in the same manner as in Example 1, except that a light reflective film (product name: IJ5000, manufactured by 3M, thickness 0.1 mm, transmittance 5%) was used as the light control layer.
The light resistance of the obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 4]
The photoelectric conversion element of Example 4 was prepared in the same manner as in Example 1, except that a light diffusing glass (ground glass) (fuse-type diffuser, product name: FS50C502, manufactured by Shibuya Optical Co., Ltd., thickness 2 mm, transmittance 30%) was used as the light control layer.
The light resistance of the obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 5]
An electric conversion element of Example 5 was produced in the same manner as in Example 1, except that a light diffusion film (manufactured by 3M, thickness 0.06 mm, transmittance 60%) was used as the light control layer.
The light resistance of the obtained electric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 6]
The photoelectric conversion element of Example 6 was prepared in the same manner as in Example 1, except that a photochromic material (photochromic ceramic window film (65%), manufactured by TintDept, decolorized state transmittance = 65%, changes to colored state with light of 380 nm or less, colored state transmittance = 45%, changes to decolorized state with light of 450 nm or more, thickness 0.1 mm) was used as the light control layer.
The light resistance of the obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.
During the measurement of power generation characteristics with a white LED, the light control layer was in a decolorized state because light of 380 nm or less was not irradiated. During the accelerated test with the light resistance tester, the light control layer was in a colored state because light of 380 nm or less was irradiated. When the power generation characteristics were measured again with a white LED, the light control layer returned to the decolorized state because light of 380 nm or less was not irradiated.

[Example 7]
The photoelectric conversion element of Example 7 was produced in the same manner as in Example 1, except that an electrochromic material (electrochromic film, manufactured by TintDept, transmittance in a decolorized state = 80%, transmittance in a colored state = 5%, thickness 0.2 mm) was used as the light control layer.
The light resistance of the obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.
The power generation characteristics were measured with a white LED in a colorless state without applying a voltage to the light control layer, and a voltage (2 V) was applied to the light control layer during the accelerated test to make it in a colored state. After 500 hours of the accelerated test, a reverse voltage (-2 V) was applied to the light control layer to change it to a colorless state, and the power generation characteristics were measured again under the white LED.

[Example 8]
The photoelectric conversion element of Example 8 was prepared in the same manner as in Example 1, except that a thermochromic material (thermochromic glass, manufactured by Nippon Sheet Glass Co., Ltd., transmittance in a bleached state = 63%, transmittance in a colored state = 13%) was used as the light control layer.
During the measurement of the power generation characteristics with a white LED, the light control layer was below 50° C., and therefore the light control layer was in a decolorized state. During the accelerated test with the light resistance tester, the light control layer was heated to above 50° C. by light irradiation, and was in a colored state. When the power generation characteristics were measured again with a white LED, the light control layer was below 50° C., and therefore the light control layer returned to the decolorized state.

[Comparative Example]
A photoelectric conversion element of the comparative example was produced in the same manner as in Example 1, except that no light control layer was provided.
The light resistance of the obtained photoelectric conversion element was evaluated in the same manner as in Example 1. The results are shown in Table 1.

From the results in Table 1, it was found that the photoelectric conversion elements of Examples 1 to 8 exhibited high retention rates. Moreover, it was found that Examples 6 to 8 not only exhibited high retention rates, but also high initial power generation amounts.
On the other hand, it was found that the photoelectric conversion element of the comparative example had a high initial power generation amount but a low maintenance rate.

The photoelectric conversion element of the present invention can reduce the amount of light incident on the light incident surface of the photoelectrode and adjust the wavelength of light incident on the light incident surface of the photoelectrode by providing a light control layer on the light incident surface side of the photoelectrode. Therefore, the photoelectric conversion element of the present invention can suppress deterioration due to ultraviolet rays and high-intensity light. Therefore, the photoelectric conversion element of this embodiment can maintain the amount of power generation for a long period of time.

Reference Signs List 1 Photoelectric conversion element 10 Photoelectrode 12 Photoelectrode support 14 Photoelectrode conductive layer 20 Counter electrode 22 Counter electrode support 24 Counter electrode conductive layer 30 Charge transfer body 40 Sealing material 50 Conductive material 60 Light control layer

Claims (4)

a photoelectrode, a counter electrode facing the photoelectrode at a distance, a charge transfer body positioned between the photoelectrode and the counter electrode, and a light control layer provided on a light incident surface side of the photoelectrode ;
The light control layer includes a photochromic material,
The photoelectric conversion element , wherein the photochromic material has a light absorption peak in a region of 400 nm or less in a decolorized state, and has a light absorption peak in a region of 400 nm or more in a colored state . a photoelectrode, a counter electrode facing the photoelectrode at a distance, a charge transfer body positioned between the photoelectrode and the counter electrode, and a light control layer provided on a light incident surface side of the photoelectrode;
The light control layer includes an electrochromic material.
A photoelectric conversion element, wherein the electrochromic material has a light absorption peak in a region of 400 nm or less in a decolorized state, and has a light absorption peak in a region of 400 nm or more in a colored state. a photoelectrode, a counter electrode facing the photoelectrode at a distance, a charge transfer body positioned between the photoelectrode and the counter electrode, and a light control layer provided on a light incident surface side of the photoelectrode;
The photoelectric conversion element , wherein the light control layer contains a thermochromic material. 4. The photoelectric conversion element according to claim 3 , wherein the thermochromic material has a light absorption peak in a region of 400 nm or less in a decolorized state, and has a light absorption peak in a region of 400 nm or more in a colored state.

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