JP2023101351A - Solar battery - Google Patents

Abstract

To provide a solar battery having improved durability.SOLUTION: A solar battery comprises a support member 10, a photoelectric conversion element 20, a water vapor concentration adjustment material 50, and an encapsulation member 30. The photoelectric conversion element 20 and the water vapor concentration adjustment material 50 are encapsulated by the support member 10 and the encapsulation member 20. The photoelectric conversion element 20 includes a perovskite compound. The photoelectric conversion element 20 may comprise a first electrode, a photoelectric conversion layer, and a second electrode in this order, for example, or may comprise the first electrode, the photoelectric conversion layer, a hole transport layer, and the second electrode in this order.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to solar cells.

In recent years, perovskite-type crystals represented by the compositional formula ABX ₃ (A is a monovalent cation, B is a divalent cation, and X is a halogen anion) and similar structures (hereinafter referred to as "perovskite compounds") have been developed. Research and development of perovskite solar cells, which are used as photoelectric conversion materials, are underway. Various efforts have been made to improve the photoelectric conversion efficiency and durability of perovskite solar cells.

Non-Patent Document 1 reports that atmospheric water vapor reacts with perovskite compounds. This reaction forms substances that do not contribute to power generation, such as lead iodide, methylammonium iodide, or hydrated compounds, on the surface and grain boundaries of the perovskite compound.

Non-Patent Document 2 discloses that water is coordinated near the main chain of a π-conjugated polymer, which is a hole transport material, to improve the conductivity of the polymer.

WO 2005/010000 discloses a perovskite solar cell with a given concentration of oxygen and water.

JP 2017-103450 A

Q. Sun, et al., Advanced Energy Materials, July 2017, Vol. 7, p. 1700977. Taka. T, Synthetic Metals, January 1993, Vol. 57, p. 5014.

An object of the present disclosure is to provide a solar cell with improved durability.

The solar cell of the present disclosure is
a support member;
a photoelectric conversion element;
a water vapor concentration adjusting material;
a sealing member;
with
The photoelectric conversion element and the water vapor concentration adjusting material are sealed by the supporting member and the sealing member,
The photoelectric conversion element contains a perovskite compound.

The present disclosure provides solar cells with improved durability.

FIG. 1 is a cross-sectional view schematically showing a first structural example of the solar cell of the first embodiment. FIG. 2 is a cross-sectional view schematically showing a second configuration example of the solar cell of the first embodiment. FIG. 3 is a cross-sectional view schematically showing a third configuration example of the solar cell of the first embodiment. FIG. 4 is a cross-sectional view schematically showing a fourth configuration example of the solar cell of the first embodiment. FIG. 5 is a cross-sectional view schematically showing a fifth configuration example of the solar cell of the first embodiment. FIG. 6 is a cross-sectional view schematically showing a sixth configuration example of the solar cell of the first embodiment. FIG. 7 is a cross-sectional view schematically showing an example of the photoelectric conversion element 20 in the solar cell according to the embodiment of the present disclosure. FIG. 8 is a cross-sectional view schematically showing the solar cell of the second embodiment.

<Knowledge on which this disclosure is based>
As reported in Non-Patent Document 1, a lead-containing perovskite compound reacts with water to deposit lead iodide, methylammonium iodide, or a hydrated compound on the surface and grain boundaries of the perovskite compound. Substances are formed that do not contribute to power generation. Since the substance has a high insulating property, movement of photo-generated carriers is inhibited. As a result, there is a problem that the characteristics of the perovskite solar cell are degraded.

Therefore, perovskite solar cells are generally used in a nitrogen atmosphere in which there is as little water as possible (for example, the water vapor concentration is 0.1 ppm or less in volume fraction).

As used herein, water vapor concentration and oxygen concentration refer to volume fraction concentrations.

WO 2005/010000 discloses a perovskite solar cell with a given concentration of oxygen and water. It is disclosed that the heat resistance of the solar cell is improved by controlling the oxygen concentration in the sealed space to 5% or more and the moisture concentration (volume fraction) to 300 ppm or less.

On the other hand, in Non-Patent Document 1, in addition to the deterioration of solar cell characteristics due to water vapor, the influence of oxygen on solar cells is reported. Specifically, in Non-Patent Document 1, the standardized photoelectric conversion efficiency after a light irradiation test of a perovskite solar cell is based on the case where the oxygen concentration around the solar cell is 0%, and the oxygen concentration is from 1% to It is disclosed to decrease monotonically as it increases up to 20%. Non-Patent Document 1 reports that the light resistance is thus lowered at an oxygen concentration of 5%. Therefore, it is expected that it is difficult to achieve both thermal stability and light stability in the oxygen concentration range of 5% or more.

Non-Patent Document 2 discloses that water is coordinated near the main chain of a π-conjugated polymer, which is a hole transport material, to improve the conductivity of the polymer. However, there has been no report that water vapor improves the thermal stability and light stability, and the presence of water vapor has been regarded as a factor in reducing the durability.

As described above, there has been no report that the presence of water vapor contributes to improving the photostability and thermal stability, which are important in actual use.

The inventors of the present invention have conducted a detailed investigation of the water vapor concentration threshold value (that is, the value at which the effect on durability is significant). We have found that there is an optimal range. Specifically, in a state where the oxygen concentration in the sealed space is suppressed to 2 ppm or less, and the water vapor concentration in the sealed space is in the range of 100 ppm or more and 5000 ppm or less, the photoelectric conversion efficiency after the light irradiation test and the heat resistance test photoelectric conversion efficiency is improved. Furthermore, it was found that the photoelectric conversion efficiency after the light irradiation test and the photoelectric conversion efficiency after the heat resistance test are further improved when the water vapor concentration in the sealed space is in the range of 100 ppm or more and 1000 ppm or less. Therefore, the photostability and thermal stability of the solar cell can be compatible when the water vapor concentration in the sealed space is in the range of 100 ppm or more and 5000 ppm or less, and the water vapor concentration in the sealed space is 100 ppm or more and 1000 ppm or less. can be improved if it is in the range of

In view of these prior arts, the present inventors have found a solar cell structure for adjusting the water vapor concentration in the region in contact with the photoelectric conversion element to a low concentration. Specifically, the photoelectric conversion element is shielded from the outside air by the sealing member, and the water vapor concentration adjusting material is provided in the sealed space. With this structure, the water vapor concentration in the region in contact with the photoelectric conversion element is controlled by the water vapor concentration adjusting material so that it becomes optimal (for example, 100 ppm or more and 5000 ppm or less, or 100 ppm or more and 1000 ppm or less) during the actual operation period. Battery durability is improved.

The solar cell of the present disclosure will be described below with reference to the drawings. In the drawing, the wiring from the photoelectric conversion element, the frame supporting the module, and the terminal box are omitted.

(First embodiment)
The solar cell of the first embodiment will be described below.

A solar cell according to a first embodiment of the present disclosure includes a support member, a photoelectric conversion element, a water vapor concentration adjusting material, and a sealing member. The photoelectric conversion element and water vapor concentration adjusting material are sealed with a support member and a sealing member. A photoelectric conversion element contains a perovskite compound.

Since the solar cell of the first embodiment has the sealing member, external air does not enter the sealed space. In addition, due to the function of the water vapor concentration adjusting material, the water vapor concentration in the region in contact with the photoelectric conversion element can be set to a low concentration range suitable for perovskite solar cells. As a result, it is possible to suppress the reaction of moisture with the perovskite compound. Furthermore, the conductivity of the hole-transporting layer can be improved by coordinating moisture to the hole-transporting material. Thereby, the conductivity of the solar cell can be improved. As a result, holes can be extracted efficiently, and recombination at the interface is less likely to occur. Therefore, when the photoelectric conversion element includes a hole transport layer, the durability of the solar cell can be further improved by the above configuration.

The water vapor concentration in the region in contact with the photoelectric conversion element may be 100 ppm or more and 5000 ppm or less. As a result, both the photostability and thermal stability of the solar cell can be achieved, and the durability can be improved. The water vapor concentration in the region in contact with the photoelectric conversion element may be 100 ppm or more and 1000 ppm or less. This can further improve the durability of the solar cell.

Hereinafter, the solar cell of the first embodiment will be described more specifically using first to sixth configuration examples. In addition, the solar cell of the first embodiment is not limited to the solar cells of the following first to sixth configuration examples.

FIG. 1 is a cross-sectional view schematically showing a first structural example of the solar cell of the first embodiment.

The solar cell 100 includes a supporting member 10 , a photoelectric conversion element 20 , a sealing member 30 and a water vapor concentration adjusting material 50 . As shown in FIG. 1 , a sealing space 40 may be formed by being surrounded by the support member 10 and the sealing member 30 . The photoelectric conversion element 20 and the water vapor concentration adjusting material 50 are arranged inside the sealed space 40 . The photoelectric conversion element 20 is supported by the supporting member 10 . A means for supporting the water vapor concentration adjusting material 50 in the sealed space 40 is not particularly limited. For example, the sealed space 40 is filled with a filler not shown in FIG. may be supported within A material that can be used as a filler will be described later. Further, the water vapor concentration adjusting material 50 may be fixed to the wall surface of the support member 10 or the sealing member 30 facing the sealing space 40 using some fixing member not shown in FIG.

The photoelectric conversion element 20 and the water vapor concentration adjusting material 50 are sealed with the supporting member 10 and the sealing member 30 .

The photoelectric conversion element 20 contains a perovskite compound.

The photoelectric conversion element 20 may be in contact with the support member 10 .

As shown in FIG. 1 , the water vapor concentration adjusting material 50 does not have to be in contact with the photoelectric conversion element 20 .

FIG. 2 is a cross-sectional view schematically showing a second configuration example of the solar cell of the first embodiment.

The solar cell 110 includes a supporting member 10 , a photoelectric conversion element 20 , a sealing member 30 and a water vapor concentration adjusting material 50 . As shown in FIG. 2 , a sealing space 40 may be formed surrounded by the support member 10 and the sealing member 30 . The photoelectric conversion element 20 is supported by the supporting member 10 . The photoelectric conversion element 20 and the water vapor concentration adjusting material 50 are arranged inside the sealed space 40 . The water vapor concentration adjusting material 50 partially covers the surface of the sealing member 30 facing the sealing space 40 .

As shown in FIG. 2 , the water vapor concentration adjusting material 50 may be in contact with the surface of the sealing member 30 facing the supporting member 10 . The water vapor concentration adjusting material 50 may be fixed to the inner wall of the sealing member 30, for example. The water vapor concentration adjusting material 50 may be in contact with the sealing member 30 so as to face the photoelectric conversion element 20 across a space.

The water vapor concentration adjusting material 50 may be formed by applying it to the sealing member 30 in manufacturing the solar cell, or may be formed by reforming a part of the inner wall of the sealing member 30 . Modification of the inner wall of the sealing member 30 includes, for example, making the surface of the sealing member 30 porous by a combination of heat treatment and chemical treatment. Such porosification can be performed when the sealing member 30 is made of, for example, glass.

FIG. 3 is a cross-sectional view schematically showing a third configuration example of the solar cell of the first embodiment.

The solar cell 120 includes a supporting member 10 , a photoelectric conversion element 20 , a sealing member 30 and a water vapor concentration adjusting material 50 . As shown in FIG. 3 , a sealing space 40 may be formed surrounded by the support member 10 and the sealing member 30 . The photoelectric conversion element 20 is supported by the supporting member 10 . The photoelectric conversion element 20 and the water vapor concentration adjusting material 50 are arranged inside the sealed space 40 . The water vapor concentration adjusting material 50 covers the entire surface of the sealing member 30 facing the sealing space 40 .

As shown in FIG. 3 , the water vapor concentration adjusting material 50 may cover the inner wall of the sealing member 30 .

The water vapor concentration adjusting material 50 may cover at least part of the surface of the photoelectric conversion element 20 . By covering at least part of the surface of the photoelectric conversion element 20 with the water vapor concentration adjusting material 50 , movement of water between the sealing space 40 and the photoelectric conversion element 20 can be delayed.

In the solar cells shown in FIGS. 1 to 3 , the water vapor concentration adjusting material 50 is not in contact with the photoelectric conversion elements 20 , but the water vapor concentration adjusting material 50 may be in contact with the photoelectric conversion elements 20 .

By the water vapor concentration adjusting material 50 being in contact with the photoelectric conversion element 20 , movement of water between the sealing space 40 and the photoelectric conversion element 20 can be delayed.

FIG. 4 is a cross-sectional view schematically showing a fourth configuration example of the solar cell of the first embodiment.

Solar cell 130 includes support member 10 , photoelectric conversion element 20 , sealing member 30 , and water vapor concentration adjusting material 50 . As shown in FIG. 4 , a sealing space 40 may be formed surrounded by the support member 10 and the sealing member 30 . The photoelectric conversion element 20 is supported by the supporting member 10 . The photoelectric conversion element 20 and the water vapor concentration adjusting material 50 are arranged inside the sealed space 40 . The water vapor concentration adjusting material 50 covers the surface of the photoelectric conversion element 20 excluding the surface in contact with the supporting member 10 .

As shown in FIG. 4 , the water vapor concentration adjusting material 50 may cover the entire photoelectric conversion elements 20 arranged on the support member 10 . That is, the photoelectric conversion element 20 may have one principal surface in contact with the support member 10 and the other principal surface and side surfaces covered with the water vapor concentration adjusting material 50 . Thereby, the photoelectric conversion element 20 does not come into contact with the sealing space 40 .

The water vapor concentration adjusting material 50 may be formed by applying it onto the photoelectric conversion element 20 in manufacturing the solar cell.

One main surface of the photoelectric conversion element 20 may be in contact with the support member 10 , and the other main surface and at least a part of the side surface may be covered with the water vapor concentration adjusting material 50 .

FIG. 5 is a cross-sectional view schematically showing a fifth configuration example of the solar cell of the first embodiment.

The water vapor concentration adjusting material 50 may cover at least part of the surface of the photoelectric conversion element 20 . At least part of the photoelectric conversion element 20 may be in contact with the sealing space 40 . In the solar cell 140 shown in FIG. 5, one main surface of the photoelectric conversion element 20 is in contact with the supporting member 10, and the other main surface and one side surface are covered with the water vapor concentration adjusting material 50. The other side surface of conversion element 20 is in contact with sealed space 40 .

When the water vapor concentration adjusting material 50 covers at least part of the surface of the photoelectric conversion element 20, the thickness of the water vapor concentration adjusting material 50 may be 0.1 μm or more and 10000 μm or less. The thickness of the water vapor concentration adjusting material 50 in this case is the minimum value of the distance from the surface of the water vapor concentration adjusting material 50 to the surface in contact with the photoelectric conversion element 20 .

When the water vapor concentration adjusting material 50 covers at least part of the surface of the photoelectric conversion element 20, the volume ratio of the water vapor concentration adjusting material 50 to the volume of the photoelectric conversion element 20 may be 10% or more and 20000% or less. It may be 20% or more and 10000% or less. When the water vapor concentration adjusting material 50 does not cover the surface of the photoelectric conversion element 20, the volume ratio of the water vapor concentration adjusting material 50 to the volume of the photoelectric conversion element 20 may be 10% or more and 1000000% or less, or 20%. It may be 500000% or more and 500000% or less.

The sealing member 30 may consist of two or more different members. FIG. 6 is a cross-sectional view schematically showing a sixth configuration example of the solar cell of the first embodiment. The solar cell 150 shown in FIG. 6 differs from the solar cell 100 in that the sealing member 30 consists of a sealing member first portion 30a and a sealing member second portion 30b. The sealing member 30 may include a first portion 30a and a second portion 30b.

The first portion 30a and the second portion 30b may have different properties and may comprise materials with different compositions. For example, the second portion 30b may have a function like an adhesive that adheres the first portion 30a and the support member 10 together.

The first portion 30a is arranged, for example, so as to face the support member 10 with a gap therebetween. The first portion 30a may be a plate-like member.

The second portion 30b is arranged, for example, between the support member 10 and the first portion 30a arranged to face the support member 10 with a gap therebetween.

One of the upper end and the lower end of the second portion 30b may be in contact with the peripheral edge of the support member 10, and the other may be in contact with the peripheral edge of the first portion 30a. As shown in FIG. 6, the second portion 30b is provided in a frame shape so as to surround the photoelectric conversion element 20 and the water vapor concentration adjusting material 50, and the first portion 30a is connected to the support member via the second portion 30b. 10 may be provided. Thereby, the sealing space 40 surrounded by the support member 10, the first portion 30a, and the second portion 30b is formed, and the photoelectric conversion element 20 and the water vapor concentration adjusting material 50 can be sealed.

Each component of the solar cell of the present disclosure will be specifically described below.

(Support member 10)
The support member 10 plays a role of supporting the photoelectric conversion element 20 .

Support member 10 may be formed from a transparent material. As the support member 10, for example, a glass substrate or a plastic substrate can be used. The plastic substrate may be, for example, a plastic film. Further, when the second electrode 27 constituting the photoelectric conversion element 20 has translucency, the material of the support member 10 may be a material that does not have translucency. For example, as the material of the support member 10, metal, ceramics, or a resin material with low translucency can be used.

(Photoelectric conversion element 20)
The photoelectric conversion element 20 contains a perovskite compound. The photoelectric conversion element 20 may include a first electrode, a photoelectric conversion layer, and a second electrode in this order. The photoelectric conversion layer contains a perovskite compound.

The photoelectric conversion element 20 may further include an electron transport layer between the first electrode and the photoelectric conversion layer, and further include a hole transport layer between the photoelectric conversion layer and the second electrode. good too. The photoelectric conversion element 20 may include a first electrode, an electron transport layer, a photoelectric conversion layer, a hole transport layer, and a second electrode in this order. A porous layer may be further provided between the electron transport layer and the photoelectric conversion layer.

FIG. 7 is a cross-sectional view schematically showing an example of the photoelectric conversion element 20 in the solar cell according to the embodiment of the present disclosure.

The photoelectric conversion element 20 includes, for example, a substrate 21, a first electrode 22, an electron transport layer 23, a porous layer 24, a photoelectric conversion layer 25, a hole transport layer 26, and a second electrode 27 in this order.

When the photoelectric conversion element 20 is irradiated with light, the photoelectric conversion layer 25 absorbs the light and generates excited electrons and holes. The excited electrons move to the first electrode 22 through the electron transport layer 23 . On the other hand, holes generated in the photoelectric conversion layer 25 move to the second electrode 27 via the hole transport layer 26 . Thereby, the photoelectric conversion element 20 can extract current from the first electrode 22 as the negative electrode and the second electrode 27 as the positive electrode.

The photoelectric conversion element 20 can be produced, for example, by the following method.

First, the first electrode 22 is formed on the surface of the substrate 21 by chemical vapor deposition, sputtering, or the like. Next, the electron transport layer 23 is formed by a chemical vapor deposition method, a sputtering method, a solution coating method, or the like. Next, the porous layer 24 is formed by a coating method or the like. Next, a photoelectric conversion layer 25 is formed. The photoelectric conversion layer 25 may be formed by, for example, a coating method using a solution, a printing method, or a vapor deposition method. Further, for example, a perovskite compound cut into a predetermined thickness may be used as the photoelectric conversion layer 25 and disposed on the porous layer 24 . Next, a hole transport layer 26 is formed on the photoelectric conversion layer 25 by chemical vapor deposition, sputtering, solution coating, or the like. Next, a second electrode 27 is formed on the hole transport layer 26 by chemical vapor deposition, sputtering, solution coating, or the like. As described above, the photoelectric conversion element 20 is obtained.

Each component of the photoelectric conversion element 20 will be specifically described below.

(substrate 21)
Substrate 21 is an additional component.

The substrate 21 plays a role of holding each layer of the photoelectric conversion element 20 .

Substrate 21 may be formed from a transparent material. As the substrate 21, for example, a glass substrate or a plastic substrate can be used. The plastic substrate may be, for example, a plastic film. Further, when the second electrode 27 has translucency, the material of the substrate 21 may be a material that does not have translucency. For example, the material of the substrate 21 can be metal, ceramics, or a resin material with low translucency.

If the first electrode 22 has sufficient strength, each layer can be held by the first electrode 22, so the substrate 21 may not be provided. In this case, the size of the first electrode 22 may be larger than that of the other layers in order to facilitate the sealing of the photoelectric conversion element 20 .

In the solar cell according to the embodiment of the present disclosure, substrate 21 may not be provided when photoelectric conversion element 20 is arranged on support member 10 . In other words, the support member 10 may function as the substrate 21 .

(First electrode 22)
The first electrode 22 has conductivity.

When the photoelectric conversion element 20 does not include the electron transport layer 23 , the first electrode 22 is made of a material that does not form an ohmic contact with the photoelectric conversion layer 25 . Furthermore, the first electrode 22 has a property of blocking holes from the photoelectric conversion layer 25 . The property of blocking holes from the photoelectric conversion layer 25 is a property of allowing only electrons generated in the photoelectric conversion layer 25 to pass through and not allowing holes to pass through. A material having such properties is a material whose Fermi energy is higher than the energy at the top of the valence band of the photoelectric conversion layer 25 . The above material may be a material having a higher Fermi energy than the photoelectric conversion layer 25 . A specific material is aluminum.

When the photoelectric conversion element 20 includes the electron transport layer 23 between the first electrode 22 and the photoelectric conversion layer 25, the first electrode 22 does not block holes from the photoelectric conversion layer 25. good. That is, the material of the first electrode 22 may be a material that forms ohmic contact with the photoelectric conversion layer 25 .

The first electrode 22 has translucency. For example, it transmits light in the visible region to the near-infrared region. The first electrode 22 is made of, for example, a transparent and conductive material. The first electrode 22 can be formed using metal oxide and/or metal nitride, for example. Examples of such materials include titanium oxide doped with at least one selected from the group consisting of lithium, magnesium, niobium, and fluorine, and doped with at least one selected from the group consisting of tin and silicon. gallium oxide, gallium nitride doped with at least one selected from the group consisting of silicon and oxygen, tin oxide doped with at least one selected from the group consisting of antimony and fluorine, boron, aluminum, gallium, and zinc oxide doped with at least one selected from the group consisting of indium, indium-tin composite oxides, or composites thereof.

The first electrode 22 may be formed by using a non-transparent material and providing a light-transmitting pattern. The pattern through which light is transmitted includes, for example, a linear pattern, a wavy line pattern, a lattice pattern, or a punching metal pattern in which a large number of fine through-holes are regularly or irregularly arranged. When the first electrode 22 has these patterns, light can pass through portions where no electrode material is present. Non-transparent electrode materials can include, for example, platinum, gold, silver, copper, aluminum, rhodium, indium, titanium, iron, nickel, tin, zinc, or alloys containing any of these. A conductive carbon material can also be used.

The light transmittance of the first electrode 22 may be, for example, 50% or more, or may be 80% or more. The wavelength of light to be transmitted depends on the absorption wavelength of the photoelectric conversion layer 25 .

The thickness of the first electrode 22 may be 1 nm or more and 1000 nm or less.

(Electron transport layer 23)
The electron transport layer 23 is arranged, for example, between the photoelectric conversion layer 25 and the first electrode 22 . By providing the electron transport layer 23 , electrons generated in the photoelectric conversion layer 25 can be efficiently transferred to the first electrode 22 . As a result, the photoelectric conversion efficiency of the photoelectric conversion element 20 can be improved because the current can be efficiently extracted.

The electron transport layer 23 is arranged, for example, between the photoelectric conversion layer 25 and the first electrode 22 . By providing the electron transport layer 23 , electrons generated in the photoelectric conversion layer 25 can be efficiently transferred to the first electrode 22 . As a result, the photoelectric conversion efficiency of the photoelectric conversion element 20 can be improved because the current can be efficiently extracted.

The electron transport layer 23 contains an electron transport material. An electron transport material is a material that transports electrons. The electron transport material can be a semiconductor. The electron transport layer 23 may be made of a semiconductor with a bandgap of 3.0 eV or more. Visible light and infrared light can be transmitted to the photoelectric conversion layer 25 by forming the electron transport layer 23 with a semiconductor having a bandgap of 3.0 eV or more.

Examples of electron transport materials are inorganic n-type semiconductors.

As the inorganic n-type semiconductor, for example, oxides of metal elements, nitrides of metal elements, and perovskite oxides can be used. Examples of oxides of metal elements include Cd, Zn, In, Pb, Mo, W, Sb, Bi, Cu, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, Si, and Cr oxides can be used. More specific examples include _TiO2 or _SnO2 . Nitrides of metal elements include, for example, GaN. Examples of perovskite oxides are _SrTiO3 or C
_aTiO3 .

The electron transport layer 23 may be made of a substance with a bandgap greater than 6.0 eV. Substances with a bandgap greater than 6.0 eV include alkali metal or alkaline earth metal halides such as lithium fluoride and calcium fluoride, alkali metal oxides such as magnesium oxide, or silicon dioxide. . In this case, the thickness of the electron transport layer 23 may be, for example, 10 nm or less in order to ensure the electron transport property of the electron transport layer 23 .

The electron transport layer 23 may include multiple layers of different materials.

The photoelectric conversion element 20 may not have the electron transport layer 23 .

(Porous layer 24)
The porous layer 24 is arranged, for example, between the electron transport layer 23 and the photoelectric conversion layer 25 .

The provision of the porous layer 24 facilitates the formation of the photoelectric conversion layer 25 . The material of the photoelectric conversion layer 25 intrudes into the voids of the porous layer 24 , and the porous layer 24 becomes a scaffold for the photoelectric conversion layer 25 . Therefore, it is difficult for the material of the photoelectric conversion layer 25 to repel or aggregate on the surface of the porous layer 24 . Therefore, the photoelectric conversion layer 25 can be easily formed as a uniform film.

The effect of increasing the optical path length of light passing through the photoelectric conversion layer 25 is also expected due to the scattering of light by the porous layer 24 . As the optical path length increases, the amount of electrons and holes generated in the photoelectric conversion layer 25 is expected to increase.

The porous layer 24 is formed on the electron transport layer 23 by, for example, a coating method. If the photoelectric conversion device 20 does not have the electron transport layer 23 , the porous layer 24 is formed on the first electrode 22 .

The porous layer 24 contains a porous body. The porous body contains voids.

The porous body is formed, for example, by a series of insulating or semiconducting particles. Examples of insulating particles are aluminum oxide particles or silicon oxide particles. Examples of semiconductor particles are inorganic semiconductor particles. Examples of inorganic semiconductors are metal oxides, perovskite oxides of metallic elements, metal sulfides or metal chalcogenides. Examples of metal oxides include Cd, Zn, In, Pb, Mo, W, Sb, Bi, Cu, Hg, Ti, Ag, Mn, Fe, V, Sn, Zr, Sr, Ga, Si, or Cr. It is an oxide. A more specific example of a metal oxide is _TiO2 . Examples of perovskite oxides of metallic elements are SrTiO ₃ or CaTiO ₃ . Examples of metal sulfides are CdS, ZnS, _In2S3 , PbS, _Mo2S , _WS2 , _S
b2S3 , _Bi2S3 , _ZnCdS2 , _{or Cu2S .} Examples of metal chalcogenides are CsSe, _In2Se3 , _WSe2 , HgS, PbSe, or _CdTe .

The thickness of the porous layer 24 may be 0.01 μm or more and 10 μm or less, or may be 0.05 μm or more and 1 μm or less.

As for the surface roughness of the porous layer 24, the surface roughness coefficient given by effective area/projected area may be 10 or more, or 100 or more. The projected area is the area of the shadow behind an object when it is illuminated directly from the front. Effective area is the actual surface area of an object. The effective area can be calculated from the volume determined from the projected area and thickness of the object, and the specific surface area and bulk density of the material forming the object. The specific surface area is measured, for example, by a nitrogen adsorption method.

Voids in the porous layer 24 are connected from the portion in contact with the photoelectric conversion layer 25 to the portion in contact with the electron transport layer 23 . That is, the voids of the porous layer 24 are connected from one main surface of the porous layer 24 to the other main surface. Thereby, the material of the photoelectric conversion layer 25 can fill the voids of the porous layer 24 and reach the surface of the electron transport layer 23 . Therefore, even if the porous layer 24 is provided, the photoelectric conversion layer 25 and the electron transport layer 23 are in direct contact with each other, so electrons can be transferred.

(Photoelectric conversion layer 25)
Photoelectric conversion layer 25 contains a perovskite compound.

A perovskite compound may be represented by the compositional formula ABX ₃ . where A is a monovalent cation, B is a divalent cation, and X is a monovalent anion.

Examples of monovalent cations A are organic cations or alkali metal cations.

Examples of organic cations are methylammonium cation ( _CH3NH3 ^{+ )} , formamidinium cation (HC( _NH2 ) _{2+ )} , ethylammonium cation ( _{CH3CH2NH3 +} ⁾ _.
, or the guanidinium cation (CH ₆ N ₃ ⁺ ).

Examples of alkali metal cations are potassium cations (K ⁺ ), cesium cations (Cs ⁺ ) or rubidium cations (Rb ⁺ ).

Examples of divalent cations B are lead cations (Pb ²⁺ ) or tin cations (Sn ²⁺ ).

Examples of monovalent anions X are halogen anions.

Each of the A, B, and X sites may be occupied by multiple types of ions.

The thickness of the photoelectric conversion layer 25 may be 50 nm or more and 10 μm or less.

The photoelectric conversion layer 25 can be formed using a coating method using a solution, a printing method, a vapor deposition method, or the like. The photoelectric conversion layer 25 may be formed by cutting out and arranging a perovskite compound.

The photoelectric conversion layer 25 may mainly contain a perovskite compound represented by the composition formula _ABX3 . Here, "the photoelectric conversion layer 25 mainly contains a perovskite compound represented by the composition formula _ABX3 " means that the photoelectric conversion layer ₂₅ contains 90% by mass or more of the perovskite compound represented by the composition formula ABX3. is. The photoelectric conversion layer 25 has a composition formula ABX ₃
may contain 95% by mass or more of the perovskite compound represented by The photoelectric conversion layer 25 may consist of a perovskite compound represented by the composition formula _ABX3 . The photoelectric conversion layer 25 may contain a perovskite compound represented by the composition formula ABX ₃ and may contain defects or impurities.

The photoelectric conversion layer 25 may further contain other compounds different from the perovskite compound represented by the composition formula ABX ₃ . Other different compounds include, for example, compounds having a Ruddlesden-Popper type layered perovskite structure.

(Hole transport layer 26)
The hole transport layer 26 is arranged, for example, between the photoelectric conversion layer 25 and the second electrode 27 . By providing the hole transport layer 26 , holes generated in the photoelectric conversion layer 25 can be efficiently transferred to the second electrode 27 . As a result, the photoelectric conversion efficiency of the photoelectric conversion element 20 can be improved because the current can be efficiently extracted.

Hole transport layer 26 contains a hole transport material. A hole-transporting material is a material that transports holes. Hole-transporting materials can be organic or inorganic semiconductors.

Hole transport layer 26 may include an organic semiconductor. The organic semiconductor forms a good interface with the photoelectric conversion layer 25, and can suppress an increase in interface defects during bonding. As a result, the photoelectric conversion efficiency and durability of the solar cell can be improved.

Organic semiconductor constituents include triphenylamine, triallylamine, phenylbenzidine, phenylenevinylene, tetrathiafulvalene, vinylnaphthalene, vinylcarbazole, thiophene, aniline, pyrrole, carbazole, triptycene, fluorene, azulene, pyrene, pentacene, and perylene. , acridine, or phthalocyanine.

Examples of typical organic semiconductors used as hole transport materials include 2,2′,7,7′-tetrakis-(N,N-di-p-methoxyphenylamine)9,9′-spirobifluorene, poly[bis( 4-phenyl)(2,4,6-trimethylphenyl)amine] (hereinafter sometimes abbreviated as "PTAA"), poly(3-hexylthiophene-2,5-diyl), poly(3,4-ethylenedioxythiophene) , copper phthalocyanine.

Inorganic semiconductors used as hole transport materials are p-type semiconductors. Examples of inorganic semiconductors are _Cu2O , _CuGaO2 , CuSCN, _CuI , _NiOx , _MoOx , _V2O5 , or carbon materials such as graphene oxide. where x>0.

Hole transport layer 26 may include multiple layers of different materials. for example,
A plurality of layers may be laminated so that the ionization potential of the hole transport layer 26 becomes smaller in order than the ionization potential of the photoelectric conversion layer 25 . This improves the hole transport properties.

The thickness of the hole transport layer 26 may be 1 nm or more and 1000 nm or less, or may be 10 nm or more and 50 nm or less. Within this range, a sufficient hole transport property can be exhibited and a low resistance can be maintained, so that photovoltaic power generation can be performed with high efficiency.

The hole transport layer 26 can be formed using a coating method, a printing method, a vapor deposition method, or the like. This is similar to the photoelectric conversion layer 25 . Examples of application methods are doctor blading, bar coating, spraying, dip coating or spin coating. An example of a printing method is screen printing. If desired, a plurality of materials may be mixed to form the hole transport layer 26 and then pressed or fired. When the material of the hole transport layer 26 is an organic low-molecular substance or an inorganic semiconductor, the hole transport layer 26 can also be produced by a vacuum deposition method.

The hole transport layer 26 may contain at least one selected from the group consisting of a supporting electrolyte, a solvent, and a dopant as an additive. The supporting electrolyte and solvent have the effect of stabilizing the holes in the hole transport layer 26 . Dopants have the effect of increasing the number of holes in hole transport layer 26 .

Examples of supporting electrolytes are ammonium salts, alkaline earth metal salts or transition metal salts. Examples of ammonium salts are tetrabutylammonium perchlorate, tetraethylammonium hexafluorophosphate, imidazolium salts or pyridinium salts. Examples of alkali metal salts are lithium perchlorate or potassium boron tetrafluoride. An example of an alkaline earth metal salt is bis(trifluoromethanesulfonyl)imide calcium(II). Examples of transition metal salts are bis(trifluoromethanesulfonyl)imidozinc(II) or tris[4-tert-butyl-2-(1H-pyrazol-1-yl)pyridine]cobalt(III) tris(trifluoromethanesulfonyl) be.

Examples of dopants are fluorine-containing aromatic boron compounds such as tris(pentafluorophenyl)borane.

The solvent contained in the hole transport layer 26 may have excellent ionic conductivity. The solvent may be an aqueous solvent or an organic solvent. To make the solute more stable, the solvent contained in the hole transport layer 26 may be an organic solvent. Specific examples include heterocyclic solvents such as tert-butylpyridine, pyridine, and n-methylpyrrolidone.

As the solvent, the ionic liquid may be used alone, or may be used by being mixed with other kinds of solvents. Ionic liquids are desirable because of their low volatility and high flame retardancy.

Examples of ionic liquids are imidazolium-based, such as 1-ethyl-3-methylimidazolium tetracyanoborate, pyridine-based, cycloaliphatic amine-based, aliphatic amine-based, or azonium amine-based.

(Second electrode 27)
The second electrode 27 has conductivity.

When the photoelectric conversion element 20 does not include the hole transport layer 26 , the second electrode 27 is the photoelectric conversion layer 25
is made of a material that does not form an ohmic contact with Furthermore, the second electrode 27 has a property of blocking electrons from the photoelectric conversion layer 25 . Here, the property of blocking electrons from the photoelectric conversion layer 25 means the property of allowing only holes generated in the photoelectric conversion layer 25 to pass therethrough and not allowing electrons to pass therethrough. A material having such properties is a material whose Fermi energy is lower than the energy at the bottom of the conduction band of the photoelectric conversion layer 25 . The above materials may be materials having a Fermi energy lower than the Fermi energy of the photoelectric conversion layer 25 . Specific materials include platinum, gold, or carbon materials such as graphene.

When the photoelectric conversion element 20 includes the hole transport layer 26 , the second electrode 27 does not have to block electrons from the photoelectric conversion layer 25 . That is, the material of the second electrode 27 may be a material that forms ohmic contact with the photoelectric conversion layer 25 . Therefore, the second electrode 27 can be formed to have translucency.

Of the first electrode 22 and the second electrode 27, at least the electrode on the light incident side should be translucent. Therefore, one of the first electrode 22 and the second electrode 27 does not have to be translucent. In other words, one of the first electrode 22 and the second electrode 27 may not use a light-transmitting material, or may not have a pattern including openings that transmit light.

(middle layer)
The photoelectric conversion element 20 may further include an intermediate layer. The intermediate layer is arranged, for example, between the electron transport layer 23 and the photoelectric conversion layer 25 . When the photoelectric conversion element 20 comprises the porous layer 24 , the intermediate layer is arranged between the porous layer 24 and the photoelectric conversion layer 25 , for example.

The intermediate layer includes fullerene (C ₆₀ ), a C ₆₀ derivative, or a self-assembled monolayer with C ₆₀ (hereinafter also referred to as “C60SAM”). The intermediate layer may be a carboxylic acid compound, a phosphoric acid compound, or a silicic acid compound.

Since the intermediate layer efficiently collects electrons, resistance losses in transporting electrons to the electron transport layer 23 are reduced. Therefore, by providing the intermediate layer, electrons generated in the photoelectric conversion layer 25 can be efficiently transferred to the electron transport layer 23 or the second electrode 27 . As a result, the photoelectric conversion efficiency of the photoelectric conversion element 20 can be improved because the current can be efficiently extracted.

Examples of C ₆₀ derivatives are [6,6]-Phenyl C ₆₁ butyric acid methyl ester or [6,6]-Phenyl-C ₆₁ butyric acid butyl ester.

An example of C60SAM is 4-(1′,5′-Dihydro-1′-methyl-2′H-[5,6]fullereno-C ₆₀ -Ih-[1,9-c]pyrrol-2′-yl ) benzoic acid, (1,2-Methanofullerene C ₆₀ )-61-carboxylic acid, or C ₆₀ Pyrrolidine tris-acid.

The intermediate layer can be formed using a coating method using a solution, a dipping method, a printing method, a vapor deposition method, or the like.

In the photoelectric conversion element 20 , the main surface of the first electrode 22 may face the support member 10 or the main surface of the second electrode 27 may face the support member 10 .

(sealing member 30)
The sealing member 30 seals the photoelectric conversion element 20 and the water vapor concentration adjusting material 50 together with the supporting member 10 . This can prevent gas such as water vapor from entering the sealed space 40 from the outside air during the actual operation period.

The sealing member 30 may contain at least one selected from the group consisting of glass, metal, ceramic, and resin.

The sealing member 30 may contain at least one selected from the group consisting of glass and resin. The sealing member 30 may be made of at least one selected from the group consisting of glass and resin. Glass has a low water vapor transmission coefficient. For example, the water vapor transmission coefficient is 3.05×10 ⁻¹⁸ cm ³ ·cm/(cm ² ·s·cmHg) or less, more preferably 3.05×10 ⁻¹⁹ cm ³ ·cm/ (cm ² ·s·cmHg) or less. A resin having a low water vapor permeability coefficient is used. Here, when the resin constituting the sealing member 30 has poor water vapor barrier properties, a gas barrier layer having a water vapor permeability coefficient of 3.05×10 ⁻¹⁸ cm ³ cm/(cm ² s cmHg) or less is used. , may be formed in the sealing member 30 made of resin. This can suppress permeation of water vapor from the outside into the sealed space 40 .

The support member 10 and the sealing member 30 may be made of the same material. The material may be glass.

When the sealing member 30 includes a sealing member first portion 30a and a sealing member second portion 30b, the first portion 30a is arranged to face the support member 10 with a gap therebetween, and the second portion The portion 30b may be arranged as an adhesive member between the support member 10 and the first portion 30a.

The first portion 30a may be a plate-like member.

In the case where the photoelectric conversion element 20 performs photoelectric conversion by absorbing light incident from the support member 10 side, the first portion 30a only needs to have a gas barrier property equivalent to that of a glass substrate, and has light transmittance. You don't have to. In this case, examples of the first portion 30a are a metal plate, a glass substrate, a ceramic plate, or a plastic substrate.

When the photoelectric conversion element 20 performs photoelectric conversion by absorbing light incident from the side opposite to the support member 10, the first portion 30a may have transparency to sunlight. In this case, an example of the material of the first portion 30a is a transparent substrate such as a glass substrate or a plastic substrate.

The second portion 30b may have gas barrier properties and high adhesion to both the support member 10 and the first portion 30a.

Examples of materials for the second portion 30b are resin materials such as epoxy resin, acrylic resin, or isoprene-isobutene copolymer resin.

The second portion 30b may contain a material that can be used for the water vapor concentration adjusting material 50, which will be described later, in order to reduce the water vapor transmission coefficient. When the second portion 30b contains, for example, a material having excellent water vapor adsorption ability among the materials that can be used for the water vapor concentration adjusting material 50, it is possible to effectively suppress the intrusion of outside air.

The sealed space 40 may contain at least one selected from the group consisting of an oxygen getter material and a filler. That is, the solar cell of the present disclosure further includes at least one selected from the group consisting of an oxygen getter material (or oxygen adsorbent) and a filler, and at least one selected from the group consisting of an oxygen getter material and a filler. One may be sealed by the support member 10 and the sealing member 30 . Thereby, the durability of the solar cell can be improved.

The oxygen getter material can suppress a rapid increase in oxygen concentration in the sealed space 40 due to deterioration of the sealing member 30 and damage to the solar cell. Therefore, the oxygen concentration in the region in contact with the photoelectric conversion element 20 can be kept low, and the durability of the solar cell can be improved.

The filler can improve the mechanical strength (in particular, impact resistance) of the solar cell.

Examples of fillers include resin materials such as ethylene-vinyl acetate copolymer resins, silicone resins, polyvinyl butyral resins, polyolefin resins, ionomer resins, and polyimide resins.

(Water vapor concentration adjusting material 50)
The water vapor concentration adjusting material 50 is sealed together with the photoelectric conversion element 20 by the supporting member 10 and the sealing member 30 . The water vapor concentration adjusting material 50 is arranged inside the sealed space 40 . The water vapor concentration adjusting material 50 can bring the water vapor concentration in the region in contact with the photoelectric conversion element 20 into a low concentration range suitable for perovskite solar cells. The water vapor concentration adjusting material 50, for example, absorbs or releases water vapor to bring the water vapor concentration of the water vapor concentration adjusting material 50 into a low concentration range suitable for perovskite solar cells. The water vapor concentration adjusting material 50, for example, absorbs or releases water vapor to bring the water vapor concentration in the sealed space 40 into a low concentration range suitable for perovskite solar cells.

The water vapor concentration adjusting material 50 includes, for example, a material having water adsorption/desorption capability. The water vapor concentration adjusting material 50 may contain a material having relatively high water adsorption/desorption capacity.

The water vapor concentration adjusting material 50 may contain at least one selected from the group consisting of inorganic materials and organic materials. The inorganic material may be an oxide. In this disclosure, organic materials include organic-inorganic hybrid materials such as porous coordination polymers.

Some oxides and organic materials have the function of adsorbing and desorbing water vapor. By using a material having a function of adsorbing and desorbing water vapor as the water vapor concentration adjusting material 50, the water vapor concentration in the sealed space can be set to a low concentration range suitable for perovskite solar cells.

Inorganic materials include aluminum oxide, cerium oxide, calcium oxide, magnesium oxide, iron oxide, phosphorus oxide, calcium chloride, zinc chloride, sodium sulfate, calcium sulfate, magnesium sulfate, magnesium perchlorate, potassium carbonate, sodium hydroxide, water. At least one selected from the group consisting of potassium oxide, molecular sieves, zeolites, porous carbon, porous silica, porous ceramics (eg, alumina gel), and metals may be included.

The inorganic material may contain at least one selected from the group consisting of cerium oxide, calcium oxide, iron oxide, zeolite, porous silica, porous carbon, porous ceramics, and metals. These materials have a relatively high ability to adsorb and desorb moisture.

The organic material may include at least one selected from the group consisting of porous coordination polymers (ie, organometallic structures), crown ethers, cyclodextrins, and resins. These materials have a relatively high ability to adsorb and desorb moisture.

The water vapor concentration adjusting material 50 includes aluminum oxide, cerium oxide, calcium oxide, magnesium oxide, iron oxide, phosphorus oxide, calcium chloride, zinc chloride, sodium sulfate, calcium sulfate, magnesium sulfate, magnesium perchlorate, potassium carbonate, and hydroxide. Sodium, potassium hydroxide, molecular sieves, zeolite, porous carbon, porous silica, porous ceramics, and metals. It may contain at least one selected from the group consisting of resins.

The water vapor concentration adjusting material 50 may contain at least one selected from the group consisting of porous coordination polymer, crown ether, and cyclodextrin, and the sealing member 30 may contain from the group consisting of glass and resin. At least one selected may be included.

The water vapor concentration adjusting material 50 may contain a water adsorbent.

The water vapor concentration adjusting material 50 may be a filler containing a water adsorbent. Examples of water sorbents are aluminum oxide, cerium oxide, calcium oxide, magnesium oxide, iron oxide, phosphorus oxide, calcium chloride, zinc chloride, sodium sulfate, calcium sulfate, magnesium sulfate, magnesium perchlorate, potassium carbonate, hydroxide Dehydrating agents such as sodium, potassium hydroxide, and metals; inorganic porous materials such as molecular sieves, zeolites, porous carbons, porous silicas, and porous ceramics (e.g., alumina gels); Organic materials such as molecules (ie, organometallic structures), crown ethers, and cyclodextrins. The material listed as a filler that the sealed space 40 may contain may be mixed with a water adsorbent.

The water vapor concentration adjusting material 50 may contain a material that does not decompose or volatilize due to heat and light. As a result, the function of adjusting the water vapor concentration can be maintained under actual usage conditions of the solar cell.

The water vapor concentration adjusting material 50 may adjust the water vapor concentration in the sealed space 40 by releasing pre-adsorbed moisture into the sealed space 40 after the solar cell is assembled. For example, water vapor may be released into the sealed space 40 by desorbing moisture that has been adsorbed by the water vapor concentration adjusting material 50 in advance by heating. The water vapor concentration adjusting material 50 may absorb an amount of water such that the water vapor concentration in the sealed space 40 is 100 ppm or more and 5000 ppm or less. The water vapor concentration adjusting material 50 may adsorb an amount of water such that the water vapor concentration in the sealed space 40 is 100 ppm or more and 1000 ppm or less.

The water vapor concentration adjusting material 50 may adjust the water vapor concentration in the sealed space 40 by adsorbing moisture in the sealed space 40 .

In order to control the amount of water vapor desorbed from the water vapor concentration adjusting material 50 or to control the water vapor concentration in the water vapor concentration adjusting material 50, the water vapor concentration adjusting material 50 is composed of a plurality of water adsorbents or moisture getter materials. may contain For the moisture getter material, for example, a material having an adsorption/desorption isotherm different from that of other materials used for the water vapor concentration adjusting material 50 may be used. In this way, a plurality of materials having different adsorption and desorption isotherms are used in combination, so that the water vapor concentration adjusting material 50 can adjust the water vapor concentration in the region where the photoelectric conversion element 20 is in contact with the photoelectric conversion element 20 to a desired range. It becomes possible to design the concentration adjusting material 50 .

The solar cell according to the first embodiment may include a plurality of water vapor concentration adjusting materials 50 in order to adjust the water vapor concentration in the sealed space 40, that is, the water vapor concentration in the region in contact with the photoelectric conversion element 20. The solar cell according to the first embodiment includes a plurality of water vapor concentration adjusting materials 50 containing different materials.
may include

The water vapor concentration in the sealed space 40 may be 100 ppm or more and 5000 ppm or less. This can suppress the perovskite compound from reacting with moisture. Furthermore, the conductivity of the hole-transporting layer can be improved by coordinating moisture to the hole-transporting material. Therefore, the conductivity of the solar cell can be improved. As a result, holes can be extracted efficiently, and recombination at the interface is less likely to occur. As described above, the durability of the solar cell can be improved.

The water vapor concentration in the sealed space 40 may be, for example, 100 ppm or more and 1000 ppm or less. This can further improve the durability of the solar cell.

The water vapor concentration in the water vapor concentration adjusting material 50 may be 100 ppm or more and 5000 ppm or less. As a result, when the photoelectric conversion element 20 is in contact with the water vapor concentration adjusting material 50, the water vapor concentration in the region in contact with the photoelectric conversion element 20 is 100 ppm or more and 5000 ppm or less. Therefore, durability of the solar cell can be improved.

The water vapor concentration in the water vapor concentration adjusting material 50 can be measured by time-of-flight secondary ion mass spectrometry (TOF-SIMS), thermal desorption spectrometry (TDS), or the like. That is, when the photoelectric conversion element 20 and the water vapor concentration adjusting material 50 are in contact with each other, the water vapor concentration in the region in contact with the photoelectric conversion element 20 is obtained by measuring the water vapor concentration in the water vapor concentration adjusting material 50 by the method described above. be done.

The water vapor concentration in the water vapor concentration adjusting material 50 may be 100 ppm or more and 1000 ppm or less. As a result, when the photoelectric conversion element 20 is in contact with the water vapor concentration adjusting material 50, the water vapor concentration in the region in contact with the photoelectric conversion element 20 is 100 ppm or more and 1000 ppm or less. Therefore, the durability of the solar cell can be further improved.

The material, number, size, position, and pre-adsorption of the water vapor concentration adjusting material 50 are such that the water vapor concentration in the sealed space 40 is in a low concentration range suitable for perovskite solar cells during the actual operation period of the solar cell. The amount of water and the like may be adjusted as appropriate. For example, from the water desorption capacity of the material used for the water vapor concentration adjusting material 50, the size of the solar cell, the volume of the sealed space 40, and the operating environment of the solar cell, the amount of water contained in the water vapor concentration adjusting material 50 and the water vapor concentration The number and size of the adjustment materials 50 are designed.

The maximum amount of water vapor adsorbed by the water vapor concentration adjusting material 50 is, for example, 10 cm ³ /g or more.
000 cm ³ /g or less.

The specific surface area of the water vapor concentration adjusting material 50 may be, for example, 10 m ² /g or more and 2000 m ² /g or less.

The pore diameter of the water vapor concentration adjusting material 50 may be, for example, 0.1 nm or more and 100 nm or less. When the water vapor concentration adjusting material 50 covers the photoelectric conversion element 20, a material from which water vapor is difficult to desorb, for example, a material containing more (for example, more than 50%) pore diameters of 0.1 nm or more and 2 nm or less may be used. good. On the other hand, when the water vapor concentration adjusting material 50 does not cover the photoelectric conversion element 20, a material that easily adsorbs and desorbs water vapor so as to easily adjust the water vapor concentration to an equilibrium state with the sealing space 40 or the filler, For example, a material with a wide pore size distribution (eg, 0.1 nm or more and 100 nm or less) may be used.

The water vapor concentration in the sealed space 40 can be measured using an atmospheric pressure ionization mass spectrometer, gas chromatography, or the like. As a specific example, for example, using an atmospheric pressure ionization mass spectrometer (API-TDS600, manufactured by Japan API Co., Ltd.), the sample package (i.e., solar cell) is destroyed in a destruction chamber under a purified argon gas atmosphere, and the package The gas component inside the package (that is, the gas component inside the sealed space 40) is detected, and the gas component inside the package is quantitatively measured using a separately prepared calibration curve. Thereby, the gas component in the sealed space 40 can be measured. The gas in the sealed space 40 can be collected by extracting the gas in the sealed space 40 with a syringe instead of breaking the sample package in the breaking chamber as described above.

Here, as an example, the gas contained in the sealing space 40 of the solar cell is allowed to flow out into a closed space such as the destruction chamber, and the concentration of water vapor in the discharged gas is measured by an atmospheric pressure ionization mass spectrometer. I will explain how. For example, solar cells are placed in a chamber filled with an inert gas such as argon or krypton. By breaking the solar cell in the chamber, the gas contained within the sealed space 40 of the solar cell is released. Next, the gas in the chamber is quantitatively analyzed with an atmospheric pressure ionization mass spectrometer. The water vapor concentration can be determined by quantifying all the components in the gas in the chamber and calculating the percentage of water vapor in the total amount. Gases other than water vapor contained within the sealed space include inert gases such as oxygen, nitrogen and noble gases, and carbon dioxide. If the sealed space 40 contains the same kind of inert gas as the inert gas that fills the chamber used for gas analysis, it may be difficult to accurately analyze the gas. Therefore, when the type of gas contained in the sealed space 40 is unknown, two identical solar cells are prepared, and different types of inert gas are used as the inert gas to fill the chamber. Each battery is analyzed for gas according to the procedure described above. By comparing the two analysis results, the composition of the gas contained within the sealed space 40 can be determined.

(Second embodiment)
The solar cell of the second embodiment will be described below. Matters described in the first embodiment may be omitted as appropriate.

In the solar cell of the second embodiment, the inside of the sealed space surrounded by the supporting member and the sealing member is filled with the photoelectric conversion element and the water vapor concentration adjusting material.

According to the above configuration, it is possible to increase the strength of the solar cell while adjusting the water vapor concentration in the region in contact with the photoelectric conversion element.

FIG. 8 is a cross-sectional view schematically showing the solar cell of the second embodiment.

In solar cell 200 , the inside of the sealed space surrounded by supporting member 10 and sealing member 30 is filled with photoelectric conversion element 20 and water vapor concentration adjusting material 50 . The water vapor concentration adjusting material 50 is in contact with the surface of the photoelectric conversion element 20 . That is, the solar cell 200 corresponds to the configuration in which the sealing space 40 in the solar cell of the first embodiment is filled with the water vapor concentration adjusting material 50 .

The inside of the sealed space surrounded by the support member 10 and the sealing member 30 may be completely filled with the photoelectric conversion elements 20 and the water vapor concentration adjusting material 50, and there may be no gaps inside the sealed space.

The water vapor concentration adjusting material 50 in the solar cell of the second embodiment may be a filler containing a water adsorbent.

The water adsorbent adsorbs and/or desorbs water vapor within the filler to adjust the water vapor concentration within the filler. That is, the water vapor concentration in the water vapor concentration adjusting material 50 filling the sealed space is adjusted. For example, the water vapor concentration is set to 100 ppm or more and 5000 ppm or less, or 100 ppm or more and 1000 ppm or less. As a result, the water vapor concentration in the region in contact with the surface of the photoelectric conversion element 20 in contact with the water vapor concentration adjusting material 50 can be set to a low concentration range suitable for perovskite solar cells.

Examples of water sorbents are aluminum oxide, cerium oxide, calcium oxide, magnesium oxide, iron oxide, phosphorus oxide, calcium chloride, zinc chloride, sodium sulfate, calcium sulfate, magnesium sulfate, magnesium perchlorate, potassium carbonate, hydroxide Dehydrating agents such as sodium, potassium hydroxide, and metals; inorganic porous materials such as molecular sieves, zeolites, porous carbons, porous silicas, and porous ceramics (e.g., alumina gels); Organic materials such as molecules (ie, organometallic structures), crown ethers, and cyclodextrins.

When the inside of the region surrounded by the support member 10 and the sealing member 30 is filled with the photoelectric conversion element 20 and the water vapor concentration adjusting material 50, the volume ratio of the water vapor concentration adjusting material 50 to the volume of the photoelectric conversion element 20 is , 10% or more and 20000% or less, or 20% or more and 10000% or less.

(Method for manufacturing solar cell)
A method for manufacturing the battery of the present disclosure will be described. As an example, a method for manufacturing the solar cell 150 shown in FIG. 6 will be described below.

First, the support member 10 is prepared. For example, a glass substrate is prepared. The glass substrate also functions as a substrate of the photoelectric conversion element 20 .

Next, the photoelectric conversion element 20 is produced on the glass substrate. First, the first electrode 22 is formed on the glass substrate. For example, the first electrode 22 is produced by forming a layer of indium-tin composite oxide on the substrate by sputtering.

An electron transport layer 23 is formed on the first electrode 22 . For example, the electron transport layer 23 is formed by forming a titanium oxide layer on the first electrode 22 by sputtering.

Next, a porous layer 24 may be formed on the electron transport layer 23 . For example, the porous layer 24 is formed by forming a layer of titanium oxide having a mesoporous structure on the electron transport layer 23 by coating.

Next, a photoelectric conversion layer 25 is formed. For example, it may be formed by applying a raw material solution of a photoelectric conversion material.

Next, a hole transport layer 26 is formed. For example, it may be formed by applying a raw material solution of the hole transport material. The raw material solution is, for example, PTAA dissolved in toluene.

Next, a second electrode 27 is formed on the hole transport layer 26 . For example, the second electrode 27 may be formed by depositing an Au film by vacuum evaporation.

Thus, the photoelectric conversion element 20 is produced on the glass substrate that is the support member 10 .

Next, the photoelectric conversion element 20 is sealed. First, a cover glass is prepared as the first portion 30a of the sealing member. A water vapor concentration adjusting material 50 is formed on a part of the cover glass by coating, for example. The water vapor concentration adjusting material 50 may be fixed with an adhesive.

Then, for example, in a glove box in which the oxygen concentration and water vapor concentration are adjusted to 0.1 ppm or less, the cover glass on which the water vapor concentration adjusting material 50 is formed and the UV curable resin as the second part 30b of the sealing member are used. Then, the photoelectric conversion element 20 is sealed. At this time, the photoelectric conversion element 20 and the water vapor concentration adjusting material 50 formed on the cover glass are sealed by the cover glass, the UV curable resin, and the glass substrate of the support member 10 . Thus, the solar cell 150 is obtained.

The manufacturing method and order of the solar cells are not limited to the above examples. In the manufacturing method described above, in the photoelectric conversion element 20 , the main surface of the first electrode 22 faces the support member 10 , but the main surface of the second electrode 27 may face the support member 10 .

INDUSTRIAL APPLICABILITY According to the present disclosure, the water vapor concentration in a region in contact with a photoelectric conversion element can be set to a low concentration range suitable for perovskite solar cells, thereby significantly improving the durability of the solar cells. It can be said that the possibility is extremely high.

REFERENCE SIGNS LIST 10 support member 20 photoelectric conversion element 21 substrate 22 first electrode 23 electron transport layer 24 porous layer 25 photoelectric conversion layer 26 hole transport layer 27 second electrode 30 sealing member 30a first portion of sealing member 30b sealing member 40 sealed space 50 water vapor concentration adjusting material 100, 110, 120, 130, 140, 150, 200 solar cell

Claims (12)

a support member;
a photoelectric conversion element;
a water vapor concentration adjusting material;
a sealing member;
with
The photoelectric conversion element and the water vapor concentration adjusting material are sealed by the supporting member and the sealing member,
The photoelectric conversion element contains a perovskite compound,
solar cell. the water vapor concentration adjusting material is in contact with the photoelectric conversion element;
The solar cell according to claim 1. The inside of the sealed space surrounded by the support member and the sealing member is
filled with the photoelectric conversion element and the water vapor concentration adjusting material,
The solar cell according to claim 1 or 2. The water vapor concentration adjusting material contains at least one selected from the group consisting of inorganic materials and organic materials.
The solar cell according to any one of claims 1 to 3. The inorganic materials include aluminum oxide, cerium oxide, calcium oxide, magnesium oxide, iron oxide, phosphorus oxide, calcium chloride, zinc chloride, sodium sulfate, calcium sulfate, magnesium sulfate, magnesium perchlorate, potassium carbonate, sodium hydroxide, at least one selected from the group consisting of potassium hydroxide, molecular sieves, zeolites, porous carbon, porous silica, porous ceramics, and metals;
The solar cell according to claim 4. The organic material comprises at least one selected from the group consisting of porous coordination polymers, crown ethers, cyclodextrins, and resins.
The solar cell according to claim 4. The solar cell according to any one of claims 1 to 6, wherein said sealing member contains at least one selected from the group consisting of glass and resin. The photoelectric conversion element comprises a first electrode, a photoelectric conversion layer, and a second electrode in this order,
The solar cell according to any one of claims 1 to 7. further comprising at least one selected from the group consisting of an oxygen getter material and a filler;
at least one selected from the group consisting of the oxygen getter material and the filler is sealed by the support member and the sealing member;
The solar cell according to any one of claims 1 to 8. The water vapor concentration in the region in contact with the photoelectric conversion element is 100 ppm or more and 5000 ppm or less.
The solar cell according to any one of claims 1-9. The water vapor concentration in the water vapor concentration adjusting material is 100 ppm or more and 5000 ppm or less.
The solar cell according to claim 10. The water vapor concentration in the sealed space surrounded by the support member and the sealing member is 100 ppm or more and 5000 ppm or less.
The solar cell according to claim 10 or 11.

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