JP2016174151A - Solar battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar battery with a high photoelectric conversion efficiency.SOLUTION: A solar battery 1 comprises: a negative electrode 2; a positive electrode 3; and a photoelectric conversion layer 4 disposed between the negative electrode 2 and the positive electrode 3. The photoelectric conversion layer 4 includes an organic inorganic perovskite compound expressed by the following general formula: R-M-X(where R represents an organic molecule, M represents a metal atom, and X represents a halogen atom or a chalcogen atom). In the solar battery, a resin layer 5 is disposed on one of the negative electrode 2 or the positive electrode 3; an inorganic layer 6 is disposed on the resin layer 5; the resin layer 5 has a surface which is wavy in geometry; and the ratio of an average length of a crest of the wave to its valley floor to its wavelength in a section of the resin layer 5 is 0.003-0.06.SELECTED DRAWING: Figure 2

Description

The present invention relates to a solar cell with high photoelectric conversion efficiency.

Conventionally, a photoelectric conversion element including a stacked body in which an N-type semiconductor layer and a P-type semiconductor layer are arranged between opposing electrodes has been developed. In such a photoelectric conversion element, photocarriers are generated by photoexcitation, and an electric field is generated by electrons moving through an N-type semiconductor and holes moving through a P-type semiconductor.

Currently, most of the photoelectric conversion elements in practical use are inorganic solar cells manufactured using an inorganic semiconductor such as silicon. However, since inorganic solar cells are expensive to manufacture and difficult to enlarge, and the range of use is limited, organic solar cells manufactured using organic semiconductors instead of inorganic semiconductors, inorganic semiconductors and organic semiconductors An organic solar cell or the like manufactured by using a semiconductor in combination has attracted attention (for example, see Patent Document 1).

In an organic solar cell, it is common to seal the cathode side or anode side of a laminate in which an N-type semiconductor layer and a P-type semiconductor layer are arranged between opposing electrodes with a resin layer (for example, non- Patent Document 1). However, sufficient durability cannot be obtained only by sealing such a resin layer, and further improvement in durability is required.
Moreover, in an organic solar cell, it is a subject that generally photoelectric conversion efficiency is low compared with an inorganic solar cell, and the further improvement of photoelectric conversion efficiency is calculated | required.

JP 2006-344794 A

Proc. of SPIE Vol. 7416 74160K-1

An object of this invention is to provide the solar cell with high photoelectric conversion efficiency.

The present invention is a solar cell having a cathode, an anode, and a photoelectric conversion layer disposed between the cathode and the anode, wherein the photoelectric conversion layer has the general formula R-M-X ₃ (provided that , R is an organic molecule, M is a metal atom, and X is a halogen atom or a chalcogen atom.) And a resin layer is disposed on either the cathode or the anode. The inorganic layer is disposed on the resin layer, the surface of the resin layer is wavy, and the ratio of the average length from the peak to the bottom of the wavelength in the cross section of the resin layer is 0.003 to 0.06. It is a certain solar cell.
The present invention is described in detail below.

The present inventors have examined the use of an organic / inorganic perovskite compound for the photoelectric conversion layer in a solar cell having a cathode, an anode, and a photoelectric conversion layer disposed between the cathode and the anode. By using the organic inorganic perovskite compound, high photoelectric conversion efficiency can be expected. In addition, the present inventors perform sealing by disposing a resin layer on either the cathode or the anode and disposing an inorganic layer on the resin layer, thereby improving the durability of the solar cell. We considered making it.
As a result, it was found that when the inorganic layer was disposed on the resin layer by a method such as sputtering, and further heated, fine surface irregularities (waves) were generated in the resin layer. The present inventors have found that the photoelectric conversion efficiency can be improved by adjusting the ratio of the average length from the peak to the valley bottom to the wavelength in such a wave shape, and have completed the present invention. . The reason why the photoelectric conversion efficiency is increased is that light incident on the solar cell is less likely to be reflected on the surface of the resin layer, and more light can be kept inside the solar cell (inside the photoelectric conversion layer). It is done.

The solar cell of this invention has a cathode, an anode, and the photoelectric converting layer arrange | positioned between the said cathode and the said anode.
In this specification, the term “layer” means not only a layer having a clear boundary but also a layer having a concentration gradient in which contained elements gradually change. In addition, the elemental analysis of a layer can be performed by performing the FE-TEM / EDS ray analysis measurement of the cross section of a solar cell, and confirming the element distribution of a specific element etc., for example. In addition, in this specification, a layer means not only a flat thin film-like layer but also a layer that can form a complicated and complicated structure together with other layers.

The materials for the cathode and the anode are not particularly limited, and conventionally known materials can be used. The anode is often a patterned electrode.
Examples of the cathode material include FTO (fluorine-doped tin oxide), 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 etc. are mentioned. Examples of anode materials include metals such as gold, conductive materials such as CuI, ITO (indium tin oxide), SnO ₂ , AZO (aluminum zinc oxide), IZO (indium zinc oxide), and GZO (gallium zinc oxide). Conductive transparent materials, conductive transparent polymers, and the like. These materials may be used alone or in combination of two or more.

The photoelectric conversion layer includes an organic inorganic perovskite compound represented by the general formula R-M-X ₃ (where R is an organic molecule, M is a metal atom, and X is a halogen atom or a chalcogen atom). The solar cell in which the photoelectric conversion layer includes the organic / inorganic perovskite compound is also referred to as an organic / inorganic hybrid solar cell.
By using the organic-inorganic perovskite compound for the photoelectric conversion layer, the photoelectric conversion efficiency of the solar cell can be improved. In addition, since the organic / inorganic perovskite compound has low moisture resistance, when the organic / inorganic perovskite compound is used in the photoelectric conversion layer, either the above-described cathode or the above-mentioned anode is used to improve the durability of the solar cell. On the other hand, it becomes more effective to dispose a resin layer and an inorganic layer as described later.

The R is an organic molecule, and is preferably represented by C ₁ N _m H _n (l, m, and n are all positive integers).
Specifically, R is, for example, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, trimethylamine, triethylamine, tripropyl. Amine, tributylamine, tripentylamine, trihexylamine, ethylmethylamine, methylpropylamine, butylmethylamine, methylpentylamine, hexylmethylamine, ethylpropylamine, ethylbutylamine, imidazole, azole, pyrrole, aziridine, azirine, Azetidine, azeto, azole, imidazoline, carbazole and their ions (eg, methylammonium (CH ₃ NH ₃ )) and fluorine And enethylammonium. Of these, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine and their ions and phenethylammonium are preferred, and methylamine, ethylamine, propylamine and these ions are more preferred.

M is a metal atom, for example, lead, tin, zinc, titanium, antimony, bismuth, nickel, iron, cobalt, silver, copper, gallium, germanium, magnesium, calcium, indium, aluminum, manganese, chromium, molybdenum, Europium etc. are mentioned. These metal atoms may be used independently and 2 or more types may be used together.

X is a halogen atom or a chalcogen atom, and examples thereof include chlorine, bromine, iodine, sulfur, and selenium. These halogen atoms or chalcogen atoms may be used alone or in combination of two or more. Among these, the halogen atom is preferable because the organic / inorganic perovskite compound becomes soluble in an organic solvent and can be applied to an inexpensive printing method by containing halogen in the structure. Furthermore, iodine is more preferable because the energy band gap of the organic-inorganic perovskite compound becomes narrow.

The organic / inorganic perovskite compound preferably has a cubic structure in which a metal atom M is disposed at the body center, an organic molecule R is disposed at each vertex, and a halogen atom or a chalcogen atom X is disposed at the face center.
FIG. 1 shows an example of a crystal structure of an organic / inorganic perovskite compound having a cubic structure in which a metal atom M is arranged at the body center, an organic molecule R is arranged at each vertex, and a halogen atom or a chalcogen atom X is arranged at the face center. It is a schematic diagram. Although details are not clear, since the orientation of the octahedron in the crystal lattice can be easily changed by having the structure described above, the mobility of electrons in the organic-inorganic perovskite compound is increased, and the photoelectric properties of the solar cell are increased. It is estimated that the conversion efficiency is improved.

The organic / inorganic perovskite compound is preferably a crystalline semiconductor. The crystalline semiconductor means a semiconductor capable of measuring the X-ray scattering intensity distribution and detecting a scattering peak. When the organic / inorganic perovskite compound is a crystalline semiconductor, the mobility of electrons in the organic / inorganic perovskite compound is increased, and the photoelectric conversion efficiency of the solar cell is improved.

In addition, the degree of crystallization can be evaluated as an index of crystallization. The degree of crystallinity is determined by separating the crystalline-derived scattering peak detected by the X-ray scattering intensity distribution measurement and the halo derived from the amorphous part by fitting, obtaining the respective intensity integrals, Can be obtained by calculating the ratio.
A preferable lower limit of the crystallinity of the organic-inorganic perovskite compound is 30%. When the crystallinity is 30% or more, the mobility of electrons in the organic / inorganic perovskite compound is increased, and the photoelectric conversion efficiency of the solar cell is improved. A more preferred lower limit of the crystallinity is 50%, and a more preferred lower limit is 70%.
Examples of the method for increasing the crystallinity of the organic / inorganic perovskite compound include thermal annealing, irradiation with intense light such as laser, and plasma irradiation.

When the photoelectric conversion layer contains the organic / inorganic perovskite compound, the photoelectric conversion layer further includes an organic semiconductor or an inorganic semiconductor in addition to the organic / inorganic perovskite compound as long as the effect of the present invention is not impaired. May be included. Note that the organic semiconductor or inorganic semiconductor referred to here may serve as an electron transport layer or a hole transport layer described later.
Examples of the organic semiconductor include compounds having a thiophene skeleton such as poly (3-alkylthiophene). In addition, for example, conductive polymers having a polyparaphenylene vinylene skeleton, a polyvinyl carbazole skeleton, a polyaniline skeleton, a polyacetylene skeleton, and the like can be given. Further, for example, compounds having a porphyrin skeleton such as a phthalocyanine skeleton, a naphthalocyanine skeleton, a pentacene skeleton, or a benzoporphyrin skeleton, a spirobifluorene skeleton, etc., and carbon-containing materials such as carbon nanotubes, graphene, and fullerene that may be surface-modified Also mentioned.

Examples of the inorganic semiconductor include titanium oxide, zinc oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, zinc sulfide, CuSCN, Cu ₂ O, CuI, MoO ₃ , V ₂ O ₅ , WO ₃ , _{MoS 2, MoSe 2, Cu 2} S , and the like.

In the case where the photoelectric conversion layer includes the organic-inorganic perovskite compound and the organic semiconductor or the inorganic semiconductor, the photoelectric conversion layer is a laminated body in which a thin-film organic semiconductor or an inorganic semiconductor portion and a thin-film organic-inorganic perovskite compound portion are stacked. Alternatively, a composite film in which an organic semiconductor or inorganic semiconductor part and an organic / inorganic perovskite compound part are combined may be used. A laminated body is preferable in that the production method is simple, and a composite film is preferable in that the charge separation efficiency in the organic semiconductor or the inorganic semiconductor can be improved.

The preferable lower limit of the thickness of the thin-film organic / inorganic perovskite compound site is 5 nm, and the preferable upper limit is 5000 nm. If the thickness is 5 nm or more, light can be sufficiently absorbed, and the photoelectric conversion efficiency is increased. If the said thickness is 5000 nm or less, since it can suppress that the area | region which cannot carry out charge separation generate | occur | produces, it will lead to the improvement of photoelectric conversion efficiency. The more preferable lower limit of the thickness is 10 nm, the more preferable upper limit is 1000 nm, the still more preferable lower limit is 20 nm, and the still more preferable upper limit is 500 nm.

When the photoelectric conversion layer is a composite film in which an organic semiconductor or an inorganic semiconductor part and an organic / inorganic perovskite compound part are combined, a preferable lower limit of the thickness of the composite film is 30 nm, and a preferable upper limit is 3000 nm. If the thickness is 30 nm or more, light can be sufficiently absorbed, and the photoelectric conversion efficiency is increased. If the said thickness is 3000 nm or less, since it becomes easy to reach | attain an electrode, a photoelectric conversion efficiency becomes high. The more preferable lower limit of the thickness is 40 nm, the more preferable upper limit is 2000 nm, the still more preferable lower limit is 50 nm, and the still more preferable upper limit is 1000 nm.

In the solar cell of the present invention, an electron transport layer may be disposed between the cathode and the photoelectric conversion layer.
The material of the electron transport layer is not particularly limited. For example, N-type conductive polymer, N-type low molecular organic semiconductor, N-type metal oxide, N-type metal sulfide, alkali metal halide, alkali metal, surface activity Specific examples include, for example, cyano group-containing polyphenylene vinylene, boron-containing polymer, bathocuproine, bathophenanthrene, hydroxyquinolinato aluminum, oxadiazole compound, benzimidazole compound, naphthalene tetracarboxylic acid compound, perylene derivative, Examples include phosphine oxide compounds, phosphine sulfide compounds, fluoro group-containing phthalocyanines, titanium oxide, zinc oxide, indium oxide, tin oxide, gallium oxide, tin sulfide, indium sulfide, and zinc sulfide.

The electron transport layer may consist of only a thin film electron transport layer, but preferably includes a porous electron transport layer. In particular, when the photoelectric conversion layer is a composite film in which an organic semiconductor or an inorganic semiconductor part and an organic / inorganic perovskite compound part are combined, a more complex composite film (a more complicated and complicated structure) is obtained. In order to increase efficiency, it is preferable that the composite film is formed on the porous electron transport layer.

The preferable lower limit of the thickness of the electron transport layer is 1 nm, and the preferable upper limit is 2000 nm. If the thickness is 1 nm or more, holes can be sufficiently blocked. If the said thickness is 2000 nm or less, it will become difficult to become resistance at the time of electron transport, and photoelectric conversion efficiency will become high. The more preferable lower limit of the thickness of the electron transport layer is 3 nm, and the more preferable upper limit is 1000 nm.

In the solar cell of the present invention, a hole transport layer may be disposed between the anode and the photoelectric conversion layer.
The material of the hole transport layer is not particularly limited, and examples thereof include a P-type conductive polymer, a P-type low molecular organic semiconductor, a P-type metal oxide, a P-type metal sulfide, and a surfactant. Examples include polystyrene sulfonate adduct of polyethylenedioxythiophene, carboxyl group-containing polythiophene, phthalocyanine, porphyrin, molybdenum oxide, vanadium oxide, tungsten oxide, nickel oxide, copper oxide, tin oxide, molybdenum sulfide, tungsten sulfide, copper sulfide. , Tin sulfide and the like, fluoro group-containing phosphonic acid, carbonyl group-containing phosphonic acid, copper compounds such as CuSCN and CuI, surface-modified carbon nanotubes, carbon-containing materials such as graphene, and the like.

The preferable lower limit of the thickness of the hole transport layer is 1 nm, and the preferable upper limit is 2000 nm. If the thickness is 1 nm or more, electrons can be sufficiently blocked. If the said thickness is 2000 nm or less, it will become difficult to become resistance at the time of hole transport, and a photoelectric conversion efficiency will become high. The more preferable lower limit of the thickness is 3 nm, the more preferable upper limit is 1000 nm, the still more preferable lower limit is 5 nm, and the still more preferable upper limit is 500 nm.

The solar cell of the present invention may further have a substrate or the like. The said board | substrate is not specifically limited, For example, transparent glass substrates, such as soda-lime glass and an alkali free glass, a ceramic substrate, a transparent plastic substrate, etc. are mentioned.

In the solar cell of the present invention, a resin layer is disposed on either the cathode or the anode, and an inorganic layer is disposed on the resin layer.
The resin layer has a wavy surface. Specifically, the ratio of the average length from the top to the bottom of the wavelength in the cross section of the resin layer is 0.003 to 0.06. When the ratio of the average length from the peak to the valley with respect to the wavelength is within the above range, the photoelectric conversion efficiency can be improved. The reason why the photoelectric conversion efficiency is increased is that light incident on the solar cell is less likely to be reflected on the surface of the resin layer, and more light can be kept inside the solar cell (inside the photoelectric conversion layer). It is done. In addition, since the gloss ratio of the surface of the solar cell can be suppressed by the ratio of the average length from the peak to the valley bottom with respect to the wavelength being within the above range, the light incident on the solar cell is reflected on the surface of the solar cell. The solar cell of the present invention is suitable when it is not desired to reflect the light (for example, when it is desired to suppress glare).

If the ratio of the average length from the peak to the valley with respect to the wavelength is 0.003 or more, the light incident on the solar cell is less likely to be reflected on the surface of the resin layer, and more light is absorbed inside the solar cell (photoelectric The inside of the conversion layer), and the photoelectric conversion efficiency of the solar cell is improved. If the ratio of the average length from the peak to the valley with respect to the wavelength is 0.06 or less, peeling of the inorganic layer or cracks due to the surface of the resin layer being wavy is suppressed, and the solar cell Improves durability. The preferable lower limit of the ratio of the average length from the peak to the valley with respect to the wavelength is 0.006, the more preferable lower limit is 0.01, the preferable upper limit is 0.04, and the more preferable upper limit is 0.02.
In addition, that the surface of the said resin layer is corrugated means that ratio of the average length from the peak to the valley bottom with respect to the said wavelength is in the said range. The ratio of the average length from the peak to the valley with respect to the wavelength is determined by using a 500 μm square section (arbitrary) of the resin layer by using an atomic force microscope (AFM) (for example, VN-8000 manufactured by Keyence Corporation). , Measured in accordance with JIS-R1683-2007, and can be calculated by calculating the wavy wavelength in the cross section (arbitrary) of the resin layer and the average length from the wavy peak to the bottom of the valley.

The specific value of the wavelength is not particularly limited as long as the ratio of the average length from the peak to the valley to the wavelength can be adjusted within the above range, but the preferable lower limit is 1 μm, the preferable upper limit is 70 μm, and the more preferable lower limit is The upper limit is preferably 10 μm and 50 μm.
The specific value of the average length from the peak to the valley bottom is not particularly limited as long as the ratio of the average length from the peak to the valley to the wavelength can be adjusted within the above range, but the preferable lower limit is 0.3 μm, and the preferable upper limit. Is 2 μm, a more preferable lower limit is 0.5 μm, and a more preferable upper limit is 1 μm.

There is no particular limitation on a method for forming a wave shape (fine surface irregularities) on the surface of the resin layer, and an inorganic layer may be disposed on the resin layer and further heated. For example, an inorganic layer may be formed on the resin layer. And a method in which the sample formed with is put in a dry oven at 70 ° C. and heated for 1 hour.
As a method for adjusting the ratio of the average length from the top to the bottom of the wavelength within the above range, for example, on the resin layer by adjusting the glass transition temperature and the linear expansion coefficient of the resin layer, for example, sputtering. A method of adjusting the degree of undulation formed in the resin layer when the inorganic layer is disposed by heating and further heating, and the linear expansion of the resin layer and the inorganic layer by adjusting the film thickness of the resin layer A method of relaxing the difference in coefficients and controlling the stress in the in-plane direction, a method of adjusting sputtering conditions when an inorganic layer is disposed on the resin layer by, for example, a sputtering method, and a thermosetting resin constituting the resin layer And a method of controlling the amount of curing shrinkage during thermal curing. By selecting the thickness of the resin layer and the type of the inorganic layer, the ratio of the average length from the peak to the valley with respect to the wavelength can be adjusted within the above range.

The preferable lower limit of the glass transition temperature of the resin layer is −60 ° C., the more preferable lower limit is 0 ° C., the still more preferable lower limit is 60 ° C., the preferable upper limit is 150 ° C., and the more preferable upper limit is 70 ° C. By adjusting the glass transition temperature of the resin layer, an inorganic layer is disposed on the resin layer by, for example, a sputtering method, and it is easy to adjust the wavy degree formed in the resin layer when further heated.
In addition, the said glass transition temperature should be measured on tension conditions (25-125 degreeC, 20 degree-C / min) using a dynamic viscoelasticity measuring apparatus (For example, DVA-200 etc. by IT measurement control company etc.). Can do. When the resin constituting the resin layer is a thermosetting resin or a photocurable resin, the glass transition temperature means a glass transition temperature after curing of the thermosetting resin or the photocurable resin.

The resin constituting the resin layer is not particularly limited as long as the ratio of the average length from the peak to the valley with respect to the wavelength can be adjusted within the above range, and may be a thermoplastic resin, a thermosetting resin, or a photocurable resin. Examples of the thermoplastic resin include butyl rubber, polyester, polyurethane, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl alcohol, polyvinyl acetate, ABS resin, polybutadiene, polyamide, polycarbonate, polyimide, polyisobutylene, and cycloolefin resin. Can be mentioned. As said thermosetting resin, an epoxy resin, an acrylic resin, a silicone resin, a phenol resin, a melamine resin, a urea resin etc. are mentioned, for example. As said photocurable resin, an epoxy resin, an acrylic resin, a vinyl resin, an ene-thiol resin etc. are mentioned, for example.

The resin layer preferably has high sputter resistance in order to adjust the ratio of the average length from the peak to the valley to the wavelength within the above range. From this viewpoint, the resin layer contains a resin having an alicyclic skeleton. It is preferable to do. The alicyclic skeleton is not particularly limited, and examples thereof include skeletons such as norbornene, isobornene, adamantane, cyclohexane, dicyclopentadiene, dicyclohexane, and cyclopentane. These skeletons may be used alone or in combination of two or more. Among these, in order to adjust the ratio of the average length from the peak to the valley bottom with respect to the wavelength within the above range, a norbornene skeleton and an isobornene skeleton are preferable.

The resin having an alicyclic skeleton is not particularly limited as long as it has an alicyclic skeleton, and may be a thermoplastic resin, a thermosetting resin, or a photocurable resin. It may be. These resins having an alicyclic skeleton may be used alone or in combination of two or more.
Further, the resin having the alicyclic skeleton may be a resin obtained by forming a resin having a reactive functional group and then crosslinking the reactive functional group.

Examples of the resin having an alicyclic skeleton include norbornene resin (TOPAS 8007S-04, manufactured by Polyplastics), isobornyl acrylate resin (TS-147, manufactured by Shin-Nakamura Chemical Co., Ltd.), and the like.

In the resin layer, the resin having the alicyclic skeleton may be mixed with a resin not having the alicyclic skeleton.

The preferable lower limit of the thickness of the resin layer is 100 nm, and the preferable upper limit is 100000 nm. If the thickness is 100 nm or more, the resin layer can sufficiently cover either the cathode or the anode. When the thickness is 100000 nm or less, water vapor entering from the side surface of the resin layer can be sufficiently blocked. The more preferable lower limit of the thickness is 500 nm, the more preferable upper limit is 50000 nm, the still more preferable lower limit is 1000 nm, and the still more preferable upper limit is 2000 nm.

In the solar cell of the present invention, an inorganic layer is disposed on the resin layer. Thereby, since the said inorganic layer has water vapor | steam barrier property and it can suppress that a water | moisture content osmose | permeates the said resin layer, durability of a solar cell can be improved.
In the solar cell of the present invention, an inorganic layer may be disposed between either the cathode or the anode and the resin layer. Also in this case, since the said inorganic layer has water vapor | steam barrier property and it can suppress that a water | moisture content osmose | permeates inside a solar cell, durability of a solar cell can be improved more.

The inorganic layer preferably contains a metal oxide, a metal nitride, or a metal oxynitride. The metal oxide, metal nitride or metal oxynitride is not particularly limited as long as it has a water vapor barrier property. For example, Si, Al, Zn, Sn, In, Ti, Mg, Zr, Ni, Ta , W, Cu, or an oxide, nitride, or oxynitride of an alloy containing two or more of these. Among these, in order to impart water vapor barrier property and flexibility to the inorganic layer, an oxide, nitride or oxynitride of a metal element containing both metal elements of Zn and Sn is preferable.

Among these, the metal oxide, metal nitride, or metal oxynitride is particularly preferably a metal oxide represented by the general formula Zn _a Sn _b O _c . By using the metal oxide represented by the general formula Zn _a Sn _b O _c for the inorganic layer, the metal oxide contains tin (Sn) atoms, and thus gives the inorganic layer appropriate flexibility. Even when the thickness of the inorganic layer is increased, the stress is reduced, so that peeling of the inorganic layer, the electrode, the semiconductor layer, and the like can be suppressed. Thereby, the water vapor | steam barrier property of the said inorganic layer can be improved, and the durability of a solar cell can be improved more.

In the metal oxide represented by the above general formula Zn _a Sn _b O _c , it is preferable that the ratio Xs (wt%) of Sn to the sum of Zn and Sn satisfies 70>Xs> 0.
The element ratio of zinc (Zn), tin (Sn), and oxygen (O) contained in the metal oxide represented by the general formula Zn _a Sn _b O _c in the inorganic layer is determined by X-ray photoelectron spectroscopy ( It can be measured using an XPS) surface analyzer (for example, ESCALAB-200R manufactured by VG Scientific).

The inorganic layer, when containing a metal oxide represented by the general formula _Zn a _Sn b _{O c,} preferably further contains silicon (Si) and / or aluminum (Al).
By adding silicon (Si) and / or aluminum (Al) to the inorganic layer, the transparency of the inorganic layer can be increased and the photoelectric conversion efficiency of the solar cell can be improved.

The preferable lower limit of the thickness of the inorganic layer is 30 nm, and the preferable upper limit is 3000 nm. When the thickness is 30 nm or more, the inorganic layer can have a sufficient water vapor barrier property, and the durability of the solar cell is improved. When the thickness is 3000 nm or less, even if the thickness of the inorganic layer is increased, the generated stress is small, and thus the peeling of the inorganic layer, the electrode, the semiconductor layer, and the like can be suppressed. The more preferable lower limit of the thickness is 50 nm, the more preferable upper limit is 1000 nm, the still more preferable lower limit is 100 nm, and the still more preferable upper limit is 500 nm.
The thickness of the inorganic layer can be measured using an optical interference film thickness measuring device (for example, FE-3000 manufactured by Otsuka Electronics Co., Ltd.).

FIG. 2 is a cross-sectional view schematically showing an example of the solar cell of the present invention.
A solar cell 1 shown in FIG. 2 has a cathode 2, an anode 3, and a photoelectric conversion layer 4 disposed between the cathode 2 and the anode 3 on a substrate 7, and a resin layer 5 on the anode 3. Are arranged, and the inorganic layer 6 is arranged on the resin layer 5. In the solar cell 1 shown in FIG. 2, the anode 3 is a patterned electrode.

The method for producing the solar cell of the present invention is not particularly limited. For example, after forming the cathode, the photoelectric conversion layer, and the anode in this order on the substrate, the resin layer is disposed on the anode, Method of sealing by disposing the inorganic layer on the resin layer, forming the anode, the photoelectric conversion layer, and the cathode in this order on the substrate, and then disposing the resin layer on the cathode And the method of sealing by arrange | positioning the said inorganic layer on the said resin layer, etc. are mentioned.

The method for forming the photoelectric conversion layer is not particularly limited, and examples thereof include a vacuum deposition method, a sputtering method, a gas phase reaction method (CVD), an electrochemical deposition method, and a printing method. Especially, the solar cell which can exhibit high photoelectric conversion efficiency can be simply formed in a large area by employ | adopting the printing method. Examples of the printing method include a spin coating method and a casting method, and examples of a method using the printing method include a roll-to-roll method.

The method of disposing the resin layer on the cathode or the anode is not particularly limited. For example, a method of sealing the cathode or the anode using a sheet-like resin layer, a resin constituting the resin layer A method in which a resin solution dissolved in an organic solvent is applied on the cathode or the anode, a liquid monomer to be a resin layer is applied on the cathode or the anode, and then the liquid monomer is polymerized by heat or UV. Examples thereof include a method, a method in which the resin layer is melted by applying heat, and then cooled.

As a method for disposing the inorganic layer on the resin layer, a vacuum deposition method, a sputtering method, a gas phase reaction method (CVD), or an ion plating method is preferable. Among these, the sputtering method is more preferable for forming a dense layer, and the DC magnetron sputtering method is more preferable among the sputtering methods. In the sputtering method, an inorganic layer can be formed by using a metal target and oxygen gas or nitrogen gas as raw materials and depositing the raw material on the resin layer to form a film.

According to the present invention, a solar cell with high photoelectric conversion efficiency can be provided.

It is a schematic diagram which shows an example of the crystal structure of an organic inorganic perovskite compound. It is sectional drawing which shows typically an example of the solar cell of this invention.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
(1) Fabrication of laminate in which cathode / electron transport layer / photoelectric conversion layer / anode are laminated On a glass substrate, an FTO film having a thickness of 1000 nm is formed as a cathode, and pure water, acetone, and methanol are used in this order. After ultrasonic cleaning for 10 minutes, it was dried.
A titanium isopropoxide ethanol solution adjusted to 2% was applied on the surface of the FTO film by a spin coating method, followed by baking at 400 ° C. for 10 minutes to form a thin-film electron transport layer having a thickness of 20 nm. Further, a titanium oxide paste containing polyisobutyl methacrylate as an organic binder and titanium oxide (a mixture of an average particle size of 10 nm and 30 nm) is applied onto the thin film electron transport layer by a spin coat method, and then heated to 500 ° C. Was fired for 10 minutes to form a porous electron transport layer having a thickness of 500 nm.
Next, CH ₃ NH ₃ I and PbCl ₂ were dissolved at a molar ratio of 3: 1 using N, N-dimethylformamide (DMF) as a solvent as a solution for forming an organic inorganic perovskite compound, and the total of CH ₃ NH ₃ I and PbCl ₂ The weight concentration was adjusted to 20%. This solution was laminated on the electron transport layer by spin coating. Further, a 1 wt% chlorobenzene solution of Poly (4-butylphenyl-diphenyl-amine) (manufactured by 1-Material) was laminated as a hole transport layer on the organic / inorganic perovskite compound site to a thickness of 50 nm by a spin coating method, and a photoelectric conversion layer Formed.
On the photoelectric conversion layer, an ITO film having a thickness of 100 nm was formed as an anode by vacuum deposition to obtain a laminate in which a cathode / electron transport layer / photoelectric conversion layer / anode were laminated.

(2) Formation of resin layer TOPAS8007S-04 (norbornene resin, Polyplastics Co., Ltd.) as a resin constituting the resin layer is formed on the anode of the laminate in which the obtained cathode / electron transport layer / photoelectric conversion layer / anode is laminated. 10% cyclohexane solution was applied by a doctor blade, and the organic solvent was dried to form a resin layer having a thickness of 10 μm.

(3) Formation of inorganic layer A sample on which a resin layer has been formed is attached to a substrate holder of a sputtering apparatus, a ZnSn alloy (Zn: Sn = 95: 5 wt%) target is applied to the cathode A of the sputtering apparatus, and Si is applied to the cathode B. A target was attached. The film forming chamber of the sputtering apparatus was evacuated by a vacuum pump, and the pressure was reduced to 5.0 × 10 ⁻⁴ Pa. Thereafter, sputtering was performed under the conditions shown in film formation condition A, and a ZnSnO (Si) thin film was formed as an inorganic layer on the resin layer to a thickness of 100 nm.
(Film formation condition A)
Argon gas flow rate: 50 sccm, oxygen gas flow rate: 50 sccm
Power output: Cathode A = 500W, Cathode B = 1500W

(4) Formation of fine surface irregularities The sample on which the inorganic layer was formed was put in a dry oven at 70 ° C. and heated for 1 hour to form fine surface irregularities to obtain a solar cell.

(5) Measurement of glass transition temperature of resin layer A 10% cyclohexane solution of TOPAS8007S-04 (norbornene resin, manufactured by Polyplastics), which is a cyclic olefin polymer as a resin constituting the resin layer, is formed on a release PET film. The sample was obtained by applying with a doctor blade, drying the organic solvent to form a resin layer having a thickness of 500 μm, and then peeling off. The glass transition temperature of the resin layer was measured under tensile conditions (25 to 125 ° C., 20 ° C./min) using a dynamic viscoelasticity measuring apparatus (DVA-200 manufactured by IT Measurement Control Co., Ltd.).

(6) Calculation of ratio of average length from top to bottom of wavelength with respect to wavelength in cross section of resin layer 500 μm square section (arbitrary) of resin layer, atomic force microscope (AFM) (VN-8000 manufactured by Keyence Corporation, etc.) ) To determine the wavy wavelength (a) in the cross section (arbitrary) of the resin layer and the average length (b) from the wavy peak to the bottom of the valley, using JIS-R1683-2007. . The ratio (b / a) was calculated from the obtained wavelength (a) and the average length (b) from the peak to the valley bottom.

(Examples 2 to 13, Comparative Examples 1 to 3)
Table 1 shows the type of photoelectric conversion layer, the resin constituting the resin layer, the glass transition temperature of the resin layer, the film thickness, the ratio of the average length from the peak to the valley to the wavelength in the cross section of the resin layer, the type of inorganic layer, etc. A solar cell was obtained in the same manner as in Example 1 except that the changes were made as shown.

(Example 2)
In “(2) Formation of resin layer”, TOPAS 9506F which is a cyclic olefin polymer as a resin constituting the resin layer is formed on the anode of the laminate in which the obtained cathode / electron transport layer / photoelectric conversion layer / anode is laminated. A solar cell was obtained in the same manner as in Example 1 except that a 10% cyclohexane solution of -04 (norbornene resin, manufactured by Polyplastics Co., Ltd.) was applied by a doctor blade and the organic solvent was dried to form a resin layer having a thickness of 3 μm. Got.

(Example 3)
In “(2) Formation of resin layer”, TOPAS 9506F which is a cyclic olefin polymer as a resin constituting the resin layer is formed on the anode of the laminate in which the obtained cathode / electron transport layer / photoelectric conversion layer / anode is laminated. A solar cell was obtained in the same manner as in Example 1 except that a 10% cyclohexane solution of -04 (norbornene resin, manufactured by Polyplastics) was applied with a doctor blade and the organic solvent was dried to form a resin layer having a thickness of 50 μm. Got.

Example 4
In “(2) Formation of resin layer”, TOPAS 9506F which is a cyclic olefin polymer as a resin constituting the resin layer is formed on the anode of the laminate in which the obtained cathode / electron transport layer / photoelectric conversion layer / anode is laminated. A solar cell was obtained in the same manner as in Example 1 except that a 10% cyclohexane solution of -04 (norbornene resin, manufactured by Polyplastics Co., Ltd.) was applied with a doctor blade and the organic solvent was dried to form a resin layer having a thickness of 100 μm. Got.

(Example 5)
In “(2) Formation of resin layer”, 4 mol% of a peroxide (Park Mill D, Park Mill D, as a curing agent) was formed on the anode of the laminate in which the obtained cathode / electron transport layer / photoelectric conversion layer / anode was laminated. A 10% cyclohexane solution of TS-147 (isobornyl acrylate resin, Shin-Nakamura Chemical Co., Ltd.), which is a thermosetting resin as a resin constituting the resin layer, is applied by a doctor blade, and 100 A solar cell was obtained in the same manner as in Example 1 except that a resin layer having a thickness of 10 μm was formed by heating at 10 ° C. for 10 minutes.

(Example 6)
In “(2) Formation of resin layer”, 4 mol% of a peroxide (Park Mill D, Park Mill D, as a curing agent) was formed on the anode of the laminate obtained by laminating the obtained cathode / electron transport layer / photoelectric conversion layer / anode. A 10% cyclohexane solution of TS-147 (isobornyl acrylate resin, Shin-Nakamura Chemical Co., Ltd.), which is a thermosetting resin as a resin constituting the resin layer, is applied by a doctor blade, and 100 A solar cell was obtained in the same manner as in Example 1, except that the resin layer having a thickness of 50 μm was formed by heating at 10 ° C. for 10 minutes.

(Example 7)
In “(2) Formation of resin layer”, 4 mol% of a peroxide (Park Mill D, Park Mill D, as a curing agent) was formed on the anode of the laminate in which the obtained cathode / electron transport layer / photoelectric conversion layer / anode was laminated. A 10% cyclohexane solution of TS-147 (isobornyl acrylate resin, Shin-Nakamura Chemical Co., Ltd.), which is a thermosetting resin as a resin constituting the resin layer, is applied by a doctor blade, and 100 A solar cell was obtained in the same manner as in Example 1 except that the resin layer having a thickness of 100 μm was formed by heating at 10 ° C. for 10 minutes.

(Example 8)
In “(2) Formation of resin layer”, OPPANOL, which is a polyisobutylene polymer as a resin constituting the resin layer, is formed on the anode of the laminate in which the obtained cathode / electron transport layer / photoelectric conversion layer / anode is laminated. In the same manner as in Example 1, except that a 10% cyclohexane solution of B-50 (polyisobutylene resin, manufactured by BASF) was applied with a doctor blade and the organic solvent was dried to form a resin layer having a thickness of 5 μm. A battery was obtained.

Example 9
In “(2) Formation of resin layer”, OPPANOL, which is a polyisobutylene polymer as a resin constituting the resin layer, is formed on the anode of the laminate in which the obtained cathode / electron transport layer / photoelectric conversion layer / anode is laminated. In the same manner as in Example 1, except that a 10% cyclohexane solution of B-50 (polyisobutylene resin, manufactured by BASF) was applied with a doctor blade and the organic solvent was dried to form a resin layer having a thickness of 10 μm. A battery was obtained.

(Example 10)
In “(2) Formation of resin layer”, OPPANOL, which is a polyisobutylene polymer as a resin constituting the resin layer, is formed on the anode of the laminate in which the obtained cathode / electron transport layer / photoelectric conversion layer / anode is laminated. In the same manner as in Example 1, except that a 10% cyclohexane solution of B-50 (polyisobutylene resin, manufactured by BASF) was applied with a doctor blade and the organic solvent was dried to form a resin layer having a thickness of 50 μm. A battery was obtained.

(Example 11)
In “(2) Formation of resin layer”, OPPANOL, which is a polyisobutylene polymer as a resin constituting the resin layer, is formed on the anode of the laminate in which the obtained cathode / electron transport layer / photoelectric conversion layer / anode is laminated. A 10% cyclohexane solution of a 1: 1 mixture of B-50 (polyisobutylene resin, manufactured by BASF) and TOPAS 9506F-04 (norbornene resin, manufactured by Polyplastics) was applied with a doctor blade, and the organic solvent was dried to a thickness of 50 μm. A solar cell was obtained in the same manner as in Example 1 except that the resin layer was formed.

(Example 12)
In “(3) Formation of inorganic layer”, a solar cell was obtained in the same manner as in Example 3, except that an SiO ₂ thin film was formed to a thickness of 100 nm by sputtering on the resin layer.

(Example 13)
In “(3) Formation of inorganic layer”, a solar cell was obtained in the same manner as in Example 3 except that an ITO thin film was formed to a thickness of 100 nm by sputtering on the resin layer.

(Comparative Example 1)
In “(2) Formation of resin layer”, TOPAS8007S which is a cyclic olefin polymer as a resin constituting the resin layer is formed on the anode of the laminate in which the obtained cathode / electron transport layer / photoelectric conversion layer / anode is laminated. A solar cell was obtained in the same manner as in Example 1 except that a 10% cyclohexane solution of -04 (norbornene resin, manufactured by Polyplastics Co., Ltd.) was applied with a doctor blade and the organic solvent was dried to form a resin layer having a thickness of 300 μm. Got.

(Comparative Example 2)
In “(2) Formation of resin layer”, 4 mol% of a peroxide (Park Mill D, Park Mill D, as a curing agent) was formed on the anode of the laminate in which the obtained cathode / electron transport layer / photoelectric conversion layer / anode was laminated. A 10% cyclohexane solution of TS-147 (isobornyl acrylate resin, Shin-Nakamura Chemical Co., Ltd.), which is a thermosetting resin as a resin constituting the resin layer, is applied by a doctor blade, and 100 A solar cell was obtained in the same manner as in Example 1 except that a resin layer having a thickness of 300 μm was formed by heating at 10 ° C. for 10 minutes.

(Comparative Example 3)
In “(2) Formation of resin layer”, TOPAS6017S which is a cyclic olefin polymer as a resin constituting the resin layer is formed on the anode of the laminate in which the obtained cathode / electron transport layer / photoelectric conversion layer / anode is laminated. A solar cell was obtained in the same manner as in Example 1 except that a 10% cyclohexane solution of -04 (norbornene resin, manufactured by Polyplastics Co., Ltd.) was applied with a doctor blade and the organic solvent was dried to form a resin layer having a thickness of 5 μm. Got.

<Evaluation>
The following evaluation was performed about the solar cell obtained by the Example and the comparative example. The results are shown in Table 1.

(1) Photoelectric conversion efficiency A power source (manufactured by KEITHLEY, 236 model) is connected between the electrodes of the solar cell, and the photoelectric conversion efficiency is measured by using a solar simulation (manufactured by Yamashita Denso Co., Ltd.) having an intensity of 100 mW / cm ^2. The obtained photoelectric conversion efficiency was defined as the initial conversion efficiency. The solar cell obtained in Comparative Example 1 was normalized based on the initial conversion efficiency.
A: Normalized value is 1.1 or more B: Normalized value is 1.0 or more and less than 1.1 x: A normalized value is less than 1.0

According to the present invention, a solar cell with high photoelectric conversion efficiency can be provided.

1 Solar cell 2 Cathode 3 Anode (patterned electrode)
4 Photoelectric conversion layer 5 Resin layer 6 Inorganic layer 7 Substrate

Claims (1)

A solar cell having a cathode, an anode, and a photoelectric conversion layer disposed between the cathode and the anode,
The photoelectric conversion layer includes an organic / inorganic perovskite compound represented by a general formula R-M-X ₃ (where R is an organic molecule, M is a metal atom, and X is a halogen atom or a chalcogen atom).
A resin layer is disposed on either the cathode or the anode,
An inorganic layer is disposed on the resin layer,
The resin layer has a wavy surface, and a ratio of an average length from a peak to a valley at a wavelength in a cross section of the resin layer is 0.003 to 0.06.

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