JP2016178290A - Solar battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar battery capable of exhibiting a high photoelectric conversion efficiency.SOLUTION: A solar battery comprises: an electrode; a counter electrode; and a photoelectric conversion layer disposed between the electrode and the counter electrode. The photoelectric conversion layer has an organic inorganic perovskite compound expressed by the general formula, R-M-X(where R represents an organic molecule, M represents a metal atom, and X represents a halogen atom or chalcogen atom), and a part including at least one element selected from a group consisting of elements of Groups 2 and 11 of the periodic table, cesium, yttrium, osmium, rhodium, manganese, antimony, titanium and lanthanum.SELECTED DRAWING: Figure 1

Description

The present invention relates to a solar cell that can exhibit 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 increase in size, and the range of use is limited, organic solar cells manufactured using organic semiconductors instead of inorganic semiconductors are attracting attention. .

In organic solar cells, fullerene is almost always used. Fullerenes are known to work mainly as N-type semiconductors. For example, Patent Document 1 describes a semiconductor heterojunction film formed using an organic compound that becomes a P-type semiconductor and fullerenes. However, in organic solar cells manufactured using fullerenes, it is known that the cause of deterioration is fullerenes (see, for example, Non-Patent Document 1), and materials that replace fullerenes are required.

Therefore, in recent years, a photoelectric conversion material having a perovskite structure using lead, tin, or the like as a central metal, which is called an organic-inorganic hybrid semiconductor, has been discovered and shown to have high photoelectric conversion efficiency (for example, Non-Patent Document 2). .

JP 2006-344794 A

Reese et al. , Adv. Funct. Mater. , 20, 3476-3483 (2010) M.M. M.M. Lee et al. , Science, 338, 643-647 (2012)

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

The present invention provides a solar cell having electrodes, a counter electrode, and a photoelectric conversion layer disposed between the electrode and the counter electrode, the photoelectric conversion layer has the general formula R-M-X ₃ (Wherein R is an organic molecule, M is a metal atom, X is a halogen atom or a chalcogen atom), a group 2 element of the periodic table, a group 11 element of the periodic table, cesium, yttrium, It is a solar cell having a portion containing one or more elements selected from the group consisting of osmium, rhodium, manganese, antimony, titanium, and lanthanum.
The present invention is described in detail below.

The present inventors use a specific organic-inorganic perovskite compound for a photoelectric conversion layer in a solar cell having an electrode, a counter electrode, and a photoelectric conversion layer disposed between the electrode and the counter electrode. investigated. By using the organic / inorganic perovskite compound, an improvement in the photoelectric conversion efficiency of the solar cell can be expected.
However, in the solar cell in which the photoelectric conversion layer contains an organic-inorganic perovskite compound, further improvement in photoelectric conversion efficiency has been a problem. On the other hand, the present inventors made a photoelectric conversion layer from an organic-inorganic perovskite compound, a periodic table group 2 element, a periodic table group 11 element, cesium, yttrium, osmium, rhodium, manganese, antimony, titanium, and lanthanum. It has been found that photoelectric conversion efficiency can be drastically improved by having a portion containing one or more elements selected from the group consisting of the following (hereinafter also referred to as “organic inorganic perovskite compound portion”). The present invention has been completed.

The solar cell of this invention has an electrode, a counter electrode, and the photoelectric converting layer arrange | positioned between the said electrode and the said counter electrode.
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 material of the said electrode and the said counter electrode is not specifically limited, A conventionally well-known material can be used. The counter electrode is often a patterned electrode.
Examples of electrode materials include FTO (fluorine-doped tin oxide), gold, silver, titanium, 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 and the like can be mentioned. Examples of the counter electrode material include metals such as gold, CuI, ITO (indium tin oxide), SnO ₂ , AZO (aluminum zinc oxide), IZO (indium zinc oxide), GZO (gallium zinc oxide), and ATO. Examples thereof include conductive transparent materials such as (antimony-doped tin oxide), conductive transparent polymers, and the like. These materials may be used alone or in combination of two or more. Further, the electrode and the counter electrode may be a cathode or an anode, respectively.

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). It has a perovskite compound site.
By using the organic-inorganic perovskite compound for the photoelectric conversion layer, the photoelectric conversion efficiency of the solar cell can be improved.

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, imidazoline, carbazole, methylcarboxyamine, ethylcarboxyamine, propylcarboxyamine, butyl Rubokishiamin, pentyl carboxyamine, hexyl carboxyamine, formamidinium, guanidine, aniline, pyridine and these ions (e.g., 3 _{NH 3)} such as methyl ammonium (CH) and the like or phenethyl ammonium and the like. Of these, methylamine, ethylamine, propylamine, propylcarboxyamine, butylcarboxyamine, pentylcarboxyamine, formamidinium, guanidine and their ions are preferred, and methylamine, ethylamine, pentylcarboxyamine, formamidinium, guanidine and These ions are more preferred. Among them, methylamine, formaminidium, and these ions are particularly preferable because high photoelectric conversion efficiency can be obtained.

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. Among these, lead or tin is preferable from the viewpoint of overlapping of electron orbits. 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.
If 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. Moreover, if the said organic inorganic perovskite compound is a crystalline semiconductor, the photoelectric conversion efficiency fall (photodegradation) by continuing irradiating light to a solar cell, especially the photodegradation resulting from the fall of a short circuit current will be suppressed.

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%. If 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. Moreover, if the said crystallinity is 30% or more, the photoelectric conversion efficiency fall (photodegradation) by continuing irradiating light to a solar cell, especially the photodegradation resulting from the fall of a short circuit current will be suppressed. A more preferred lower limit of the crystallinity is 50%, and a more preferred lower limit is 70%.
Examples of a method for increasing the crystallinity of the organic / inorganic perovskite compound include thermal annealing (heat treatment), irradiation with intense light such as a laser, and plasma irradiation.

When performing the thermal annealing (heat treatment), the temperature for heating the organic / inorganic perovskite compound is not particularly limited, but is preferably 100 ° C. or higher and lower than 250 ° C. When the heating temperature is 100 ° C. or higher, the crystallinity of the organic / inorganic perovskite compound can be sufficiently increased. If the said heating temperature is less than 250 degreeC, it can heat-process, without thermally degrading the said organic-inorganic perovskite compound. A more preferable heating temperature is 120 ° C. or higher and 230 ° C. or lower. The heating time is not particularly limited, but is preferably 3 minutes or longer and 2 hours or shorter. When the heating time is 3 minutes or longer, the crystallinity of the organic-inorganic perovskite compound can be sufficiently increased. If the heating time is within 2 hours, the organic inorganic perovskite compound can be heat-treated without causing thermal degradation.
These heating operations are preferably performed in a vacuum or under an inert gas, and the dew point temperature is preferably 10 ° C or lower, more preferably 7.5 ° C or lower, and further preferably 5 ° C or lower.

The organic-inorganic perovskite compound portion contains at least one element selected from the group consisting of Group 2 elements of the periodic table, Group 11 elements of the periodic table, cesium, yttrium, osmium, rhodium, manganese, antimony, titanium, and lanthanum. .
When the organic / inorganic perovskite compound portion contains these elements, the photoelectric conversion efficiency of the solar cell can be improved.
As the at least one element selected from the group consisting of Group 2 elements of the periodic table, Group 11 elements of the periodic table, cesium, yttrium, osmium, rhodium, manganese, antimony, titanium and lanthanum, specifically, for example, barium, Examples include strontium, calcium, silver, copper, cesium, yttrium, osmium, rhodium, manganese, antimony, titanium, and lanthanum. From the viewpoint of further improving the photoelectric conversion efficiency, one or more elements selected from the group consisting of barium, strontium, calcium, silver, copper, cesium, manganese and lanthanum are preferable. Further, from the viewpoint of suppressing a decrease in photoelectric conversion efficiency (photodegradation) due to continuous irradiation with light, one or more elements selected from the group consisting of calcium, strontium, silver, copper, manganese and lanthanum are more preferable. One or more elements selected from the group consisting of calcium, strontium, silver and copper are particularly preferred.

The ratio (mol%) of the content of at least one element selected from the group consisting of the above-mentioned periodic table group 2 element, periodic table group 11 element, cesium, yttrium, osmium, rhodium, manganese, antimony, titanium and lanthanum is Although not particularly limited, a preferable lower limit with respect to 100 mol% of the metal element (M represented by R-M—X ₃ ) in the organic / inorganic perovskite compound is 0.01 mol%, and a preferable upper limit is 20 mol%. When the content ratio (mol%) is 0.01 mol% or more, the photoelectric conversion efficiency is lowered (photodegradation) by continuing to irradiate the solar cell with light, particularly the short-circuit current density and the fill factor are lowered. The resulting light degradation is suppressed. When the content ratio (mol%) is 20 mol% or less, it is possible to suppress a decrease in initial conversion efficiency due to the presence of the element. A more preferable lower limit of the content ratio (mol%) is 0.1 mol%, and a more preferable upper limit is 10 mol%.

The method of containing at least one element selected from the group consisting of the above periodic table group 2 element, periodic table group 11 element, cesium, yttrium, osmium, rhodium, manganese, antimony, titanium and lanthanum is not particularly limited, For example, the method of mixing the halide of the said element with the solution used when forming the layer of an organic inorganic perovskite compound is mentioned.

The photoelectric conversion layer may further contain an organic semiconductor or an inorganic semiconductor in addition to the organic / inorganic perovskite compound as long as the effects of the present invention are not impaired. 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 electrode 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 (buffer 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 site and an organic / inorganic perovskite compound are combined, a more complex composite film (a more complicated structure) is obtained, and the photoelectric conversion efficiency is improved. In order to increase the thickness, 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 material for a hole transport layer may be laminated between the photoelectric conversion layer and the counter electrode.
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 compounds having a thiophene skeleton such as poly (3-alkylthiophene). In addition, for example, conductive polymers having a triphenylamine skeleton, 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, a benzoporphyrin skeleton, a spirobifluorene skeleton, etc., molybdenum oxide, vanadium oxide, tungsten oxide, nickel oxide, copper oxide, tin oxide, sulfide Examples thereof include molybdenum, tungsten sulfide, copper sulfide, tin sulfide, etc., fluoro group-containing phosphonic acid, carbonyl group-containing phosphonic acid, copper compounds such as CuSCN and CuI, and carbon-containing materials such as carbon nanotubes and graphene.

A part of the material for the hole transport layer may be immersed in the photoelectric conversion layer, or may be disposed in a thin film on the photoelectric conversion layer. As for the thickness when the material of the hole transport layer is present in a thin film, the preferable lower limit 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 metal substrate, a transparent plastic substrate, etc. are mentioned.

The solar cell of the present invention has a laminate (that is, disposed as necessary) having an electrode, a counter electrode, and a photoelectric conversion layer disposed between the electrode and the counter electrode as described above. The electrode, the electron transport layer, the photoelectric conversion layer, and the hole transport layer and the counter electrode, if necessary, formed on the substrate, are sealed with a sealing material. It is preferable. The photoelectric conversion efficiency of a solar cell can be improved because the said laminated body is sealed with the sealing material. Here, it is preferable that the sealing material covers the entire laminated body so as to close an end portion thereof. The sealing material is not particularly limited as long as it has a barrier property, and examples thereof include a thermosetting resin, a thermoplastic resin, and an inorganic material.

Examples of the thermosetting resin and thermoplastic resin include epoxy resin, acrylic resin, silicon resin, phenol resin, melamine resin, urea resin, butyl rubber, polyester, polyurethane, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl alcohol, poly Examples include vinyl acetate, ABS resin, polybutadiene, polyamide, polycarbonate, polyimide, polyisobutylene and the like.

The preferable lower limit of the thickness of the sealing material is 100 nm, and the preferable upper limit is 100000 nm. A more preferable lower limit of the thickness is 500 nm, a more preferable upper limit is 50000 nm, a still more preferable lower limit is 1000 nm, and a still more preferable upper limit is 20000 nm.

Examples of the inorganic material include 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 sealing material, oxides, nitrides, or oxynitrides of metal elements containing both metal elements of Zn and Sn are preferable.

Among the sealing materials, the method for sealing the laminate with the thermosetting resin and the thermoplastic resin is not particularly limited, for example, a method for sealing the laminate with a sheet-like sealing material, A method in which a sealing material solution in which a sealing material is dissolved in an organic solvent is applied to the laminate, a liquid monomer serving as a sealing material is applied to the laminate, and then the liquid monomer is crosslinked or polymerized by heat or UV. And a method of cooling after sealing the sealing material by applying heat.

Among the sealing materials, a vacuum deposition method, a sputtering method, a gas phase reaction method (CVD), and an ion plating method are preferable as a method of covering the stacked body with the inorganic material. Of these, the sputtering method is 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 made of an inorganic material can be formed by using a metal target and oxygen gas or nitrogen gas as raw materials and depositing the raw material on the laminate to form a film.
The sealing material may be a combination of the thermosetting resin and thermoplastic resin and the inorganic material.

In the solar cell of the present invention, the sealing material may be further covered with other materials such as a glass plate, a resin film, a resin film coated with an inorganic material, and a metal foil. That is, the solar cell of the present invention may have a configuration in which the laminate and the other materials are sealed, filled, or bonded with the sealing material. Thereby, even if there is a pinhole in the sealing material, water vapor can be sufficiently blocked, and the durability of the solar cell can be further improved.

The method for producing the solar cell of the present invention is not particularly limited, and for example, the electrode, the electron transport layer, the photoelectric conversion layer, if necessary, on the substrate disposed as necessary. Examples include a method of forming the hole transport layer and the counter electrode in this order to produce the laminate, and then sealing the laminate with the sealing material.

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.

ADVANTAGE OF THE INVENTION According to this invention, the solar cell which can exhibit 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.

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) Preparation of coating solution containing titanium 10 mmol of titanium powder was precisely weighed and placed in a beaker, 40 g of hydrogen peroxide solution was added, and 10 g of ammonia solution was further added. After cooling this with water for 2 hours, 30 mmol of L-lactic acid was added and heated for one day on a hot plate set at 80 ° C., and 10 ml of distilled water was added thereto to prepare a coating solution containing titanium.
(2) Fabrication of solar cell An FTO film having a thickness of 1000 nm was formed as an electrode (cathode) on a glass substrate, ultrasonically cleaned using pure water, acetone, and methanol in this order for 10 minutes each and then dried.
A coating solution containing titanium was applied by a spin coating method at a rotation speed of 1500 rpm. After the application, it was baked at 550 ° C. for 10 minutes in the atmosphere to form an electron transport layer.
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 300 nm. Subsequently, lead iodide as a metal halide compound was dissolved in N, N-dimethylformamide (DMF) to prepare a 1M solution. Further, in order to add copper, the lead iodide in the DMF solution has a concentration of 0.01M (copper content (additive concentration in the table) = 1 mol% with respect to 100 mol% of lead). Copper chloride was dissolved as an additive, and this was formed on the porous electron transport layer by spin coating. Further, methylammonium iodide as an amine compound was dissolved in 2-propanol to prepare a 1M solution. A layer containing CH ₃ NH ₃ PbI ₃ which is an organic / inorganic perovskite compound is formed by immersing a sample in which the above lead iodide (including an additive) is formed in this solution, thereby forming an organic / inorganic perovskite compound. A site was formed. After immersion, the obtained sample was heat-treated at 80 ° C. for 30 minutes. 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, a gold film having a thickness of 100 nm was formed as a counter electrode (anode) by vacuum deposition, and a laminate was manufactured. On the obtained laminate, aluminum foil in which 10 μm of polyisobutylene resin (OPPANOL100 manufactured by BASF) as a sealing material was laminated at 100 ° C. was laminated to obtain a solar cell.

(Examples 2 to 16)
A solar cell was obtained in the same manner as in Example 1 except that the additive was changed to the compound / addition amount shown in Table 1 and the hole transport layer was changed to that shown in Table 1.

(Examples 17 and 18)
As a solution for forming an organic / inorganic perovskite compound, CH ₃ NH ₃ I and PbI ₂ were dissolved in a molar ratio of 1: 1 using N, N-dimethylformamide (DMF) as a solvent on the porous electron transport layer of Example 1. , Pb concentration was adjusted to 1M. Further, in order to add strontium or titanium, the concentration of 0.01M (the content of strontium or titanium (in the table, additive concentration) = 1 mol% with respect to 100 mol% of lead) was added to the prepared solution. Thus, strontium chloride or titanium iodide was dissolved as an additive, and this was formed on the porous electron transport layer by a spin coating method to form an organic / inorganic perovskite compound site. 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, a gold film having a thickness of 100 nm was formed as a counter electrode (anode) by vacuum deposition, and a laminate was manufactured. On the obtained laminate, aluminum foil in which 10 μm of polyisobutylene resin (OPPANOL100 manufactured by BASF) as a sealing material was laminated at 100 ° C. was laminated to obtain a solar cell.

(Example 19)
As a solution for forming an organic / inorganic perovskite compound, CH ₃ NH ₃ I and PbCl ₂ were dissolved in a molar ratio of 3: 1 on the porous electron transport layer of Example 1 using N, N-dimethylformamide (DMF) as a solvent. , Pb concentration was adjusted to 1M. Further, in order to add strontium, the additive was added to the prepared solution so as to have a concentration of 0.01M (the content of strontium (additive concentration in the table) = 1 mol% with respect to 100 mol% of lead). As a result, strontium chloride was dissolved and formed on the porous electron transport layer by a spin coating method to form an organic / inorganic perovskite compound site. 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, a gold film having a thickness of 100 nm was formed as a counter electrode (anode) by vacuum deposition, and a laminate was manufactured. On the obtained laminate, aluminum foil in which 10 μm of polyisobutylene resin (OPPANOL100 manufactured by BASF) as a sealing material was laminated at 100 ° C. was laminated to obtain a solar cell.

(Example 20)
A solar cell was obtained in the same manner as in Example 1 except that the laminate was not sealed with a sealing material.

(Comparative Example 1)
A solar cell was obtained in the same manner as in Example 1 except that no additive was used when preparing the organic / inorganic perovskite compound forming solution.

(Comparative Example 2)
A solar cell was obtained in the same manner as in Example 3 except that no additive was used when preparing the organic / inorganic perovskite compound forming solution.

(Comparative Example 3-7)
A solar cell was obtained in the same manner as in Example 1 except that the types and concentrations of additives used in preparing the organic / inorganic perovskite compound forming solution were changed as shown in Table 1.

(Comparative Example 8)
A solar cell was obtained in the same manner as in Example 17 except that no additive was used when preparing the organic / inorganic perovskite compound forming solution.

(Comparative Example 9)
A solar cell was obtained in the same manner as in Example 19 except that no additive was used in preparing the organic / inorganic perovskite compound forming solution.

<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) Initial conversion efficiency A power source (manufactured by KEITHLEY, model 236) is connected between the electrodes of the solar cell, and light with an intensity of 100 mW / cm ² is irradiated using solar simulation (manufactured by Yamashita Denso Co., Ltd.). It was measured. In Examples 1-16 and 20 and Comparative Example 2-7, when the conversion efficiency of Comparative Example 1 was normalized to 1, the case of 1.1 or more was ◯, 1 or more, and less than 1.1. The case where it was less than 1 was marked as x, and in Examples 17-18, when the conversion efficiency of Comparative Example 8 was normalized to 1, the case where it was 1.1 or more was rated as ◯ 1, 1 or more The case where it was less than 1.1, the case where it was less than 1, and the case where it was less than 1, and x, when the conversion efficiency of Comparative Example 9 was normalized to 1 for Example 19, it was 1.1 or more. A case where it was 1 or more and less than 1.1 was evaluated as a case where it was less than 1 or less than 1.
(2) Photodegradation test A power source (manufactured by KEITHLEY, model 236) was connected between the electrodes of the solar cell, and light having an intensity of 100 mW / cm ² was irradiated using a solar simulation (manufactured by Yamashita Denso). The photoelectric conversion efficiency immediately after starting light irradiation and the photoelectric conversion efficiency after continuing light irradiation for 1 hour were measured, respectively. The photoelectric conversion efficiency after 1 hour of light irradiation / the value of the photoelectric conversion efficiency immediately after the start of light irradiation is obtained, and the value is 0.9 or more, ◯◯, 0.8 or more, 0 The case where it was less than 0.9, ◯, 0.6 or more, and the case where it was less than 0.8, was given as ◯, and the case where it was less than 0.6, as x.

ADVANTAGE OF THE INVENTION According to this invention, the solar cell which can exhibit high photoelectric conversion efficiency can be provided.

Claims (5)

A solar cell having an electrode, a counter electrode, and a photoelectric conversion layer disposed between the electrode and the counter electrode,
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), and a periodic table. A sun having a part containing at least one element selected from the group consisting of Group 2 elements, Group 11 elements of the periodic table, cesium, yttrium, osmium, rhodium, manganese, antimony, titanium and lanthanum battery. The proportion of the content of at least one element selected from the group consisting of Group 2 elements of the periodic table, Group 11 elements of the periodic table, cesium, yttrium, osmium, rhodium, manganese, antimony, titanium and lanthanum is an organic / inorganic perovskite compound The solar cell according to claim 1, wherein the content is 0.01 mol% or more and 20 mol% or less with respect to 100 mol% of the metal element therein. One or more elements selected from the group consisting of group 2 elements of the periodic table, group 11 elements of the periodic table, cesium, yttrium, osmium, rhodium, manganese, antimony, titanium and lanthanum are calcium, strontium, silver, copper, manganese The solar cell according to claim 1, wherein the solar cell is one or more elements selected from the group consisting of lanthanum and lanthanum. One or more elements selected from the group consisting of group 2 elements of the periodic table, group 11 elements of the periodic table, cesium, yttrium, osmium, rhodium, manganese, antimony, titanium and lanthanum are composed of calcium, strontium, silver and copper The solar cell according to claim 3, wherein the solar cell is one or more elements selected from the group. A laminated body having an electrode, a counter electrode, and a photoelectric conversion layer disposed between the electrode and the counter electrode is sealed with a sealing material. 3. The solar cell according to 3 or 4.

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