JP2016178167A - Photoelectrode and manufacturing method therefor, and solar battery and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a photoelectrode having a light absorption layer including a perovskite compound; a method for manufacturing such a photoelectrode, which need not include a sintering step as a requisite; a solar battery using such a photoelectrode; and a method for manufacturing such a solar battery.SOLUTION: A method for manufacturing a photoelectrode 9 having a conductive base material 8, an underlying layer 3 laminated on the base material 8, and a light absorption layer 7 including an organic inorganic perovskite compound and formed on the surface of the underlying layer 3 and in the underlying layer, or at least in the underlying layer comprises: a step of forming the underlying layer 3 by blowing, against the base material 8, at least any one kind of fine particles of N-type semiconductor fine particles and insulator fine particles, which have the organic inorganic perovskite compound deposited thereto. It is preferred that the organic inorganic perovskite compound is a compound expressed by the following composition formula (I): ABX(I) [where A represents an organic cation, B represents a metal ion, and X represents a halogen ion].SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a photoelectrode that does not require a baking treatment, a photoelectrode manufactured by the manufacturing method, a method for manufacturing a solar cell using the photoelectrode, and a solar cell manufactured by the manufacturing method.

  Organic-inorganic hybrid perovskite compounds have attracted attention as sensitizers that can replace the dyes of dye-sensitized solar cells. A solid solar cell using an organic hole transport layer of bifluorene-type low molecular weight sprio-OMeTAD formed on the surface of a crystal layer (perovskite compound layer) made of this perovskite compound shows 10.9% photoelectric conversion efficiency. Has been reported (see Non-Patent Document 1). Starting with this report, further improvements in photoelectric conversion efficiency have been reported one after another (see Non-Patent Document 2), and development for practical use is becoming active. In order to put it to practical use, it is required not only to improve the photoelectric conversion efficiency but also to reduce the manufacturing cost.

“Efficient Hybrid Solar Cells Based on Meso-Superstructured Organometal Halide Perovskites” Science, 2012, 338, p643-. “Solvent engineering for high-performance inorganic-organic hybrid perovskite solar cells” Nature Materials 2014, 13, p897-.

  Conventionally, a porous film obtained by applying a paste containing titania fine particles and a binder resin onto a conductive glass substrate and firing this coating film has been used as a base for the perovskite compound layer. However, since the baking process at about 500 ° C. for 30 to 60 minutes is a factor that increases the manufacturing cost, it is required to form the porous film at a low temperature and in a short time.

  The present invention has been made in view of the above circumstances, and does not require a firing step, a method for producing a photoelectrode having a light absorption layer containing a perovskite compound, a photoelectrode, and a solar cell using the photoelectrode It is an object to provide a manufacturing method and a solar cell.

[1] A base material having conductivity, a base layer laminated on the base material, and a light absorption layer containing an organic / inorganic perovskite compound formed at least inside the surface and the inside of the base layer. A photoelectrode having a step of forming the underlayer by spraying at least one of N-type semiconductor fine particles and insulator fine particles to which the organic / inorganic perovskite compound is attached to the base material Manufacturing method.
[2] The method for producing a photoelectrode according to the above [1], wherein the N-type semiconductor fine particles are fine particles composed of at least one selected from ZnO, TiO ₂ and SnO.
[3] The method for producing a photoelectrode according to the above [1], wherein the insulating fine particles are fine particles comprising at least one selected from Al ₂ O ₃ , ZrO ₂ and MgO.
[4] The method for producing a photoelectrode according to any one of [1] to [3], wherein the N-type semiconductor fine particles and the insulating fine particles have an average particle diameter of 10 nm to 70 nm.
[5] The method for producing a photoelectrode according to any one of [1] to [4], wherein the organic-inorganic perovskite compound is represented by the following composition formula (I).
ABX ₃ (I)
[Wherein, A represents an organic cation, B represents a metal ion, and X represents a halogen ion. ]
[6] A photoelectrode manufactured by the method according to any one of [1] to [5].
[7] A method for producing a solar cell comprising the photoelectrode according to [6] and a counter electrode, wherein the photoelectrode is produced by the method according to any one of [1] to [5]. And a step of disposing the counter electrode on the surface of the light absorption layer of the photoelectrode.
[8] A method for manufacturing a solar cell comprising the photoelectrode according to [6], a hole transport layer, and a counter electrode, wherein the method is any one of [1] to [5]. Obtaining the photoelectrode by the method, forming the hole transport layer on the light absorption layer of the photoelectrode, and disposing the counter electrode on the hole transport layer. A method for manufacturing a solar cell.
[9] The method for manufacturing a solar cell according to [8], wherein the hole transport layer is formed on a surface of the light absorption layer, and the counter electrode is disposed on the surface of the hole transport layer.
[10] A solar cell comprising the photoelectrode according to [6] above and a counter electrode.
[11] A solar cell manufactured by the method according to any one of [7] to [9].

  According to the method for manufacturing a photoelectrode and a solar cell according to the present invention, since the base layer of the light absorption layer containing the perovskite compound can be formed at room temperature without firing, the manufacturing cost can be reduced. Furthermore, since a resin film with low heat resistance can be applied as a base material for forming the base layer, a film-type solar cell applicable to a wide variety of installation forms and various uses can be manufactured at low cost.

It is the cross-sectional schematic diagram which showed an example of the laminated structure of the photoelectrode concerning this invention. It is a schematic block diagram of the film forming apparatus applicable to the manufacturing method of the photoelectrode concerning this invention.

  Hereinafter, the present invention will be described with reference to the drawings based on preferred embodiments, but the present invention is not limited to such embodiments. In the present specification, “film” and “layer” are not distinguished unless otherwise specified.

<< Photoelectrode >>
The first embodiment of the photoelectrode of the present invention is a photoelectrode 9 shown in FIG. The photoelectrode 9 includes a conductive substrate 1, a block layer 2 laminated on the surface of the substrate 1, an underlayer 3 laminated on the surface of the block layer 2 on the substrate 1, And a light absorption layer 7 containing an organic / inorganic perovskite compound formed at least inside the surface and the inside.
In the present specification, the organic / inorganic perovskite compound is simply referred to as “perovskite compound”.

  In the photoelectrode 9, the conductive substrate 1 and the block layer 2 are collectively referred to as a base material 8. When either one of the conductive substrate 1 and the block layer 2 is not arranged, the remaining other arranged is the base material 8. In the photoelectrode 9, the base layer 3 is disposed on the surface of the substrate 8.

  The underlayer 3 of the photoelectrode 9 is a porous film, and a perovskite compound is contained inside the porous film. Further, an upper layer 4 made of a perovskite compound is laminated on the surface of the porous film. The porous film (underlayer 3) containing the perovskite compound supported by the porous structure and the perovskite compound layer (upper layer 4) composed of the perovskite compound located above the underlayer 3 are combined to absorb light. Called layer 7.

  In the photoelectrode 9, the upper layer 4 is not an essential component, and the light absorption layer 7 may be formed only of the underlayer 3 containing crystals of a perovskite compound.

  The underlayer 3 may be a non-porous dense film instead of the porous film. Even in this case, the perovskite compound is contained in the dense film.

  In the photoelectrode 9, the block layer 2 is not essential, but the block layer 2 is preferably disposed between the conductive substrate 1 and the light absorption layer 7. By disposing the block layer 2, it is possible to prevent the conductive substrate 1 and the light absorption layer 7 from being in direct contact with each other and improve the photoelectric conversion efficiency. The block layer 2 is preferably a dense layer made of an N-type semiconductor.

The perovskite compound layer included in the light absorption layer 7 has a crystal structure and exhibits light absorption by band gap excitation in the same manner as a typical compound semiconductor. In the crystal composed of CH ₃ NH ₃ PbI ₃ known as a perovskite compound, PbI ₂ is responsible for visible light absorption, and compared with the sensitizing dye of the dye-sensitized solar cell, the extinction coefficient per unit thickness (cm ^{− 1} ) is known to be one digit higher.

  The photoelectrode 9 constitutes the solar cell 10 shown in FIG. 1, the hole transport layer 5 is formed on the surface of the upper layer 4 of the photoelectrode 9, and the counter electrode 6 is disposed on the surface of the hole transport layer 5. ing. When the upper layer 4 is not disposed, the hole transport layer 5 or the counter electrode 6 is formed on the surface of the base layer 3. Details of the hole transport layer 5 and the counter electrode 6 will be described later.

  Suitable materials, thicknesses, and the like of each configuration of the photoelectrode 9 according to the present invention will be exemplified in the following description of the manufacturing method.

<< Photoelectrode Manufacturing Method >>
As a first embodiment of the method for producing a photoelectrode of the present invention, a method for producing the photoelectrode 9 illustrated in FIG. 1 will be described.
<Preparation of substrate 1>
The kind in particular of the board | substrate 1 which comprises the base material 8 is not restrict | limited, For example, the transparent substrate used for the photoelectrode of the conventional solar cell is mentioned. Examples of the transparent substrate include substrates made of glass or synthetic resin, synthetic resin films, and the like. The substrate 1 includes a flexible film having flexibility.

  In the manufacturing method of this embodiment in which the underlayer 3 is formed by spraying at least one of N-type semiconductor fine particles and insulator fine particles, high-temperature baking is not essential, and the underlayer 3 can be formed at room temperature. Therefore, a substrate having a glass transition temperature of less than 200 ° C., for example, a synthetic resin substrate, a film, or the like can be applied as the substrate 1. Therefore, since many kinds of substrates can be used as compared with the conventional one, it is possible to manufacture solar cells having various perovskite compounds according to a wider range of purposes and applications than conventional ones.

  When the material of the substrate 1 is glass, examples of the glass include known glasses such as soda lime glass, borosilicate glass, quartz glass, borosilicate glass, Vycor glass, alkali-free glass, blue plate glass, and white plate glass. Can be mentioned.

  When the material of the substrate 1 is a synthetic resin, examples of the synthetic resin include polyacrylic resin, polycarbonate resin, polyester resin, polyimide resin, polystyrene resin, polyvinyl chloride resin, and polyamide resin. Among these, polyester resins, particularly polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) are preferable from the viewpoint of manufacturing a thin, light and flexible solar cell.

The surface of the substrate 1 is preferably coated with a metal oxide constituting the transparent conductive layer. This coating can impart conductivity to the surface of the substrate 1 without impairing the transparency. As the metal oxide, a compound used for a transparent conductive layer of a known solar cell can be applied. For example, tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), zinc oxide, tin oxide, antimony dope Examples thereof include tin oxide (ATO), indium oxide / zinc oxide (IZO), and gallium oxide / zinc oxide (GZO).
The transparent conductive layer made of the metal oxide may be a single layer or a plurality of layers.

The substrate 1 used in the present embodiment can be manufactured by a conventional method, and a commercially available product may be used.
The thickness and material of the substrate 1 are not particularly limited, and examples thereof include a glass substrate having a thickness of 1 mm to 10 mm and a resin film having a thickness of 0.01 mm to 3 mm.
The thickness of the transparent conductive layer provided on the surface of the substrate 1 is not particularly limited as long as desired conductivity can be obtained, and examples thereof include about 1 nm to 10 μm.

<Formation of block layer 2>
In order to prevent the loss of electromotive force due to direct contact between the transparent conductive layer on the surface of the substrate 1 and the perovskite compound constituting the light absorption layer 7, the surface of the transparent conductive layer of the substrate 1 is made of an N-type semiconductor. It is preferable to dispose the block layer 2. In order to prevent the above loss, it is preferable to dispose the non-porous dense block layer 2.

Examples of the N-type semiconductor constituting the block layer 2 include oxide semiconductors excellent in electron conductivity such as ZnO, TiO ₂ , SnO, IGZO, SrTiO ₃ , and the like. Among these, TiO ₂ is particularly preferable because of its excellent electron conductivity.
There may be one type of N-type semiconductor constituting the block layer 2 or a plurality of types.

The number of layers of the block layer 2 may be one, or two or more.
Although the total thickness of the block layer 2 is not specifically limited, For example, about 1 nm-1 micrometer are mentioned. When the thickness is 1 nm or more, the effect of preventing the loss is sufficiently obtained, and when the thickness is 1 μm or less, the internal resistance can be kept low.

  The formation method of the block layer 2 is not specifically limited, The well-known method which can form the dense layer which consists of N type semiconductor by desired thickness on the surface of the transparent conductive layer of the board | substrate 1 is applicable. For example, known methods such as a sputtering method, a vapor deposition method, and a sol-gel method in which a dispersion liquid containing an N-type semiconductor precursor is applied.

Examples of N-type semiconductor precursors include titanium tetrachloride (TiCl ₄ ), peroxotitanic acid (PTA), titanium alkoxide such as titanium ethoxide and titanium isopropoxide (TTIP), zinc alkoxide, alkoxysilane, and zirconium. Examples thereof include metal alkoxides such as alkoxides.

<Formation of underlayer 3>
1st embodiment of the manufacturing method of the photoelectrode of this invention is formed in at least inside among the base material 8 which has electroconductivity, the base layer 3 laminated | stacked on the base material 8, and the surface of the base layer 3, and the inside. And a photoabsorptive layer 7 containing the organic-inorganic perovskite compound (hereinafter sometimes referred to simply as a perovskite compound), wherein the N-type semiconductor fine particles and the perovskite to which the perovskite compound is attached There is a step of forming the underlayer 3 containing the perovskite compound inside by spraying at least one of the insulating fine particles to which the compound is adhered onto the substrate 8. The base material 8 includes the conductive substrate 1 and the block layer 2 described above.

  In the manufacturing method of the present embodiment, at least one of N-type semiconductor fine particles and insulator fine particles to which a perovskite compound is attached is sprayed onto the base material 8 to join the base material 8 and the fine particles, and the fine particles are joined together. And forming a base layer 3.

  The method of spraying the fine particles onto the base material 8 is not particularly limited, and a conventional powder spraying method can be applied. For example, the aerosol deposition method (AD method) in which the fine particles are accelerated by a carrier gas, the fine particles by electrostatic force. Examples include an accelerated electrostatic fine particle coating method (electrostatic spray method), a cold spray method, and the like. Among these methods, the AD method is preferable because it is easy to adjust the speed of the fine particles to be sprayed, and it is easy to adjust the strength and layer thickness of the underlying layer 3 to be formed.

  The AD method is a method in which fine particles are accelerated to a subsonic to supersonic speed by a carrier gas such as nitrogen and sprayed onto a substrate to form a film made of fine particles on the substrate surface. The fine particles that have been sprayed collide with the fine particles that have been bonded to the surface of the substrate, thereby forming a film in which the fine particles are bonded. In the collision between the fine particles, a temperature rise that causes the fine particles to melt hardly occurs. Moreover, since the formed porous film has sufficient strength and electron conductivity as an electrode of a solar cell, a sintering step after film formation is not essential. However, sintering (firing) may be performed as necessary.

  By appropriately adjusting the speed of the fine particles to be sprayed, the film forming rate and the porosity of the film can be adjusted. Usually, the higher the spray rate, the higher the film-forming rate and the lower the membrane porosity. Accordingly, when the underlayer 3 is formed, the underlayer 3 can be formed by arbitrarily selecting the film structure of the porous film or the dense film by adjusting the spraying speed of the fine particles.

  As a method of adjusting the spraying speed, for example, the opening diameter of the spray nozzle (the diameter of the opening or the length of one side of the opening) can be adjusted. As the opening diameter is increased, the spraying speed can be decreased. As the opening diameter is decreased, the spraying speed can be increased. For example, by spraying fine particles (small-sized fine particles or large-sized fine particles) conveyed by nitrogen gas through a nozzle opening having an opening diameter of 1 mm or less, acceleration can be achieved to 10 to 1000 m / s, for example. The spraying speed of the fine particles is not particularly limited and is appropriately set according to the material of the base material.

The type of the N-type semiconductor constituting the N-type semiconductor fine particles is not particularly limited, and a known inorganic semiconductor can be applied. For example, an inorganic semiconductor that can be formed into fine particles having a particle diameter of about 10 nm to 100 μm is available. preferable. Examples of such an inorganic semiconductor include an oxide semiconductor that constitutes a photoelectrode of a conventional dye-sensitized solar cell. Specific examples include oxide semiconductors excellent in electronic conductivity such as titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO, SnO ₂ ), IGZO, strontium titanate (SrTiO ₃ ), and the like. . In some cases, a compound semiconductor such as Si, Cd, or ZnS doped with a pentavalent element may be used. Of these, titanium oxide is particularly preferable because of its excellent electron conductivity.
As the inorganic semiconductor, one kind of inorganic semiconductor may be used, or two or more kinds of inorganic semiconductors may be used in combination.

In general, titanium oxide (titania) used industrially is roughly classified into anatase type and rutile type, and brookite type and amorphous titanium oxide are also known.
When titanium oxide is used as the N-type semiconductor, any of the above types of titanium oxide may be used, and titanium oxide in which a plurality of types are mixed may be used.

The kind of insulator constituting the insulator fine particles is not particularly limited, and a known inorganic insulator can be applied. For example, an inorganic insulator that can be formed into fine particles having a particle diameter of about 10 nm to 100 μm is available. preferable. Examples of such an inorganic insulator include an oxide that constitutes an insulating layer of a conventional semiconductor device. Specific examples include zirconium dioxide, silicon dioxide, aluminum oxide (AlO, Al ₂ O ₃ ), magnesium oxide (MgO), nickel oxide (NiO), and the like. Of these, aluminum (III) (Al ₂ O ₃ ) is particularly preferable because of its excellent dispersibility.
As the inorganic insulator, one kind of inorganic insulator may be used, or two or more kinds of inorganic insulators may be used in combination.

  As the fine particles to be sprayed to form the underlayer 3, one or more types of N-type semiconductor fine particles and one or more types of insulator fine particles may be used in combination.

The average particle diameter r of the fine particles is preferably 1 nm ≦ r <200 nm, more preferably 10 nm ≦ r ≦ 70 nm, and further preferably 10 nm ≦ r ≦ 30 nm.
The larger the value is above the lower limit of the above range, the easier it is to insert the perovskite compound sufficiently into the pores constituting the porous structure of the underlayer 3. The smaller the value is below the upper limit of the above range, the more the interface between the perovskite compound and the N-type semiconductor fine particles increases, the photoelectrons can be easily taken out, and the underlayer 3 and the hole transport layer 5 come into contact with each other to lose the electromotive force. Can be prevented.

  The average particle diameter r of the fine particles can be obtained as an average value of particle diameters measured by observing a plurality of fine particles with an electron microscope. In this case, the larger the number of fine particles to be measured, the better. For example, 10 to 50 particles may be measured and the arithmetic average thereof may be obtained. Or it can also determine as a peak value of the particle diameter (volume average diameter) distribution obtained by the measurement of the laser diffraction type particle size distribution measuring apparatus. If the measurement sample of the same fine particles is measured by the above two methods and the measured values are different from each other, whether or not they are included in the above average particle diameter range based on the values obtained by observation with an electron microscope. judge.

  The method for measuring the average particle size of the fine particles is not limited to the two types of methods (electron microscope observation or laser diffraction particle size distribution measurement), and may be measured by other known methods. Even if the particle diameter measured by other known methods is outside the above-mentioned preferred range, the fine particle is not limited to the present embodiment as long as it is measured by the above two methods and falls within the above-mentioned particle diameter range. Fine particles having a suitable particle size in

  As a method for attaching the perovskite compound to the fine particles, a raw material to which the perovskite compound crystallized is adhered by immersing the fine particles in a raw material solution in which a perovskite compound or a precursor of the perovskite compound is dissolved and further drying the solvent. The method of obtaining particle | grains is mentioned. Details of the perovskite compound will be described later.

  The amount of the perovskite compound attached to the fine particles is not particularly limited. For example, about 50 to 100% of the fine particle surface is about 1 to 20% of the diameter of the fine particles, for example, a thickness of about 0.1 nm to 20 nm. Can be attached.

  The underlayer 3 is preferably formed as a porous film having pores into which a perovskite compound can be inserted later. By inserting the perovskite compound into the porous film of the underlayer 3 later, the amount of the perovskite compound contained in the porous film increases, so that the light absorption efficiency can be further increased and the photoelectric conversion efficiency can be further improved. Can do.

The average pore diameter of the porous film constituting the underlayer 3 is preferably 1 nm to 100 nm or more, more preferably 5 nm to 80 nm, and still more preferably 10 nm to 50 nm.
When it is at least the lower limit of the above range, the perovskite compound can be sufficiently inserted into the pores. The intensity | strength of a porous membrane can be raised as it is below the upper limit of the said range.
The average pore diameter can be measured by a known gas adsorption test or mercury intrusion test.

The porous or non-porous thickness as the underlayer 3 is not particularly limited, and is preferably 10 nm to 10 μm, preferably 50 nm to 1 μm, and more preferably 100 nm to 0.5 μm, for example.
When it is at least the lower limit of the above range, a scaffold suitable for crystallization of the perovskite compound constituting the upper layer 4 is obtained. Furthermore, a large number of perovskite compounds can be inserted into the pores of the porous film, so that the light absorption efficiency can be further increased and the photoelectric conversion efficiency can be further improved.
If it is not more than the upper limit of the above range, the efficiency with which the photoelectrons generated in the light absorption layer 7 reach the conductive substrate 8 via the underlayer 3 is increased, and the photoelectric conversion efficiency can be further improved.

<Formation of the light absorption layer 7>
In the photoelectrode 9, a light absorption layer 7 comprising a porous film (underlayer 3) containing a perovskite compound and an upper layer 4 formed on the surface of the porous film contains crystals of the perovskite compound. When the crystal of the perovskite compound absorbs light, photoelectrons and holes are generated in the crystal. Photoelectrons move to the working electrode (positive electrode) formed by the substrate 1, and holes move to the counter electrode (negative electrode) formed by the counter electrode 6 via the hole transport layer 5.

The perovskite compound used in the present embodiment is not particularly limited as long as it can generate an electromotive force by light absorption, and a known perovskite compound is applicable. Among these, perovskite-type crystals can be formed, and the following composition formula (1) having an organic component and an inorganic component in a single compound:
ABX ₃ (1)
The perovskite compound represented by these is preferable.

  In the composition formula (1), A represents an organic cation, B represents a metal cation, and X represents a halogen ion. In the perovskite crystal structure, the B site can take octahedral coordination with the X site. It is considered that the metal cation at the B site and the atomic orbital of the halogen ion at the X site are mixed to form a valence band and a conduction band related to photoelectric conversion.

The metal constituting the metal cation represented by B in the composition formula (1) is not particularly limited, and examples thereof include Cu, Ni, Mn, Fe, Co, Pd, Ge, Sn, Pb, and Eu. Among these, Pb and Sn are preferable because they can easily form a highly conductive band by hybridization with the atomic orbitals of halogen ions at the X site.
The metal cation constituting the B site may be one type or two or more types.

The halogen constituting the halogen ion represented by X in the composition formula (1) is not particularly limited, and examples thereof include F, Cl, Br, and I. Among these, Cl, Br, and I are preferable because they can easily form a highly conductive band by a hybrid orbital with a metal cation at the B site.
There may be one kind of halogen ion constituting the X site, or two or more kinds.

The organic group constituting the organic cation represented by A in the composition formula (1) is not particularly limited, and examples thereof include alkylammonium derivatives and formamidinium derivatives.
The organic cation constituting the A site may be one type or two or more types.

  Examples of the organic cation formed by the alkyl ammonium derivative include carbon such as methyl ammonium, dimethyl ammonium, trimethyl ammonium, ethyl ammonium, propyl ammonium, isopropyl ammonium, tert-butyl ammonium, pentyl ammonium, hexyl ammonium, octyl ammonium, and phenyl ammonium. Examples include primary or secondary ammonium having an alkyl group of 1 to 6. Of these, methylammonium, which can easily obtain a perovskite crystal, is preferable.

  Examples of the organic cation formed by the formamidinium derivative include formamidinium, methylformamidinium, dimethylformamidinium, trimethylformamidinium, and tetramethylformamidinium. Of these, formamidinium is preferred because a perovskite crystal can be easily obtained.

As a suitable perovskite compound represented by the composition formula (1), for example, CH ₃ NH ₃ PbI ₃ , CH ₃ NH ₃ PbI _3-h Cl _h (h represents 0 to ₃ ), CH ₃ NH ₃ PbI _{The following} composition formula (2) such as _3-j Br _j (j represents 0 to 3):
RNH ₃ PbX ₃ (2)
The alkylamino lead halide represented by these is mentioned. In the composition formula (2), R represents an alkyl group, and X represents a halogen ion. Since the perovskite compound having this composition formula has a wide absorption wavelength range and can absorb a wide wavelength range of sunlight, excellent photoelectric conversion efficiency can be obtained.

  The alkyl group represented by R in the composition formula (2) is preferably a linear, branched or cyclic saturated or unsaturated alkyl group having 1 to 6 carbon atoms. It is more preferably a chain saturated alkyl group, and further preferably a methyl group, an ethyl group, or an n-propyl group. With these suitable alkyl groups, perovskite crystals can be easily obtained.

  The perovskite compound constituting the light absorption layer 7 is attached in advance to the raw material fine particles constituting the underlayer 3. After forming the underlayer 3, as a method for adding the perovskite compound to the inside or the surface of the underlayer 3, a raw material solution in which the perovskite compound or a perovskite compound precursor is dissolved is applied to the surface of the underlayer 3, and the solvent is added. A method of adding a perovskite crystal by drying is mentioned.

  The reaction in which the perovskite compound is formed from the precursor can occur at room temperature, but may be heated to promote this reaction. Moreover, you may anneal a perovskite type crystal | crystallization at about 80-150 degreeC from a viewpoint of improving photoelectric conversion efficiency. Furthermore, you may heat or sinter at the temperature exceeding 150 degreeC as needed.

  At least a part of the raw material solution applied to the underlayer 3 penetrates into the porous film of the underlayer 3, and crystallization proceeds with drying of the solvent, and perovskite crystals are formed in the porous film. In addition, by applying a sufficient amount of the raw material solution, the raw material solution that has not penetrated into the porous film forms perovskite crystals on the surface of the porous film together with the drying of the solvent, and consists of perovskite crystals. The upper layer 4 is formed. The perovskite crystal constituting the upper layer 4 and the perovskite crystal in the underlayer 3 are integrally formed, and the light absorption layer 7 is integrally formed.

  Examples of the precursor contained in the raw material solution include a halide (BX) containing the B site metal ion and the X site halogen ion, the A site organic cation, and the X site halogen ion. A halide (AX) containing. A single raw material solution containing halide (AX) and halide (BX) may be applied to the underlayer 3, or two raw material solutions each containing halide individually may be applied in turn to the underlayer 3. You may apply to.

  The solvent of the raw material solution is not particularly limited as long as it dissolves the raw material and does not impair the underlayer 3. For example, ester, ketone, ether, alcohol, glycol ether, amide, nitrile, carbonate, halogenated hydrocarbon , Hydrocarbons, sulfones, sulfoxides and the like.

  As an example, a halogenated alkylamine and a lead halide are dissolved in a mixed solvent of γ-butyrolactone (GBL) and dimethyl sulfoxide (DMSO), and the solution is applied to the underlayer 3 and dried, whereby the composition formula (2 The perovskite type crystal which consists of the perovskite compound represented by this is obtained. Furthermore, as described in Non-Patent Document 2, after applying a solvent miscible with GBL or DMSO, such as toluene or chloroform, on the perovskite crystal, annealing is performed at about 100 ° C. You may add the process to do. This additional treatment may improve crystal stability and increase photoelectric conversion efficiency.

  The concentration of the raw material in the raw material solution is not particularly limited, and is preferably a concentration that is sufficiently dissolved and exhibits a viscosity that allows the raw material solution to penetrate into the porous membrane.

  The amount of the raw material solution applied to the underlayer 3 is not particularly limited. For example, the raw material solution penetrates all or at least a part of the porous film and has an upper layer having a thickness of about 1 nm to 1 μm on the surface of the porous film. A coating amount such that 4 is formed is preferable.

The method for applying the raw material solution to the underlayer 3 is not particularly limited, and known methods such as a gravure coating method, a bar coating method, a printing method, a spray method, a spin coating method, a dip method, and a die coating method can be applied.
Application | coating of the said raw material solution with respect to the base layer 3 may be completed by 1 time, and you may repeat application | coating after the 2nd time after drying. The application amount after the second time may be the same as or different from the first application amount.

The method for drying the raw material solution applied to the underlayer 3 is not particularly limited, and known methods such as natural drying, reduced pressure drying, and hot air drying can be applied.
The drying temperature of the raw material solution applied to the underlayer 3 may be a temperature at which the crystallization of the perovskite compound proceeds sufficiently, and examples thereof include a range of 4 to 40 ° C.

  By the manufacturing method of the present embodiment described above, a photoelectrode 9 including the base material 8 made of the conductive substrate 1 and the block layer 2 and the light absorption layer 7 made of the base layer 3 and the upper layer 4 is obtained. . The explanation of the film forming method by the AD method will be supplemented below.

<< Film formation method by AD method >>
FIG. 2 is a configuration diagram of a film forming apparatus 60 applicable to the present embodiment. However, the film forming apparatus used in the film forming method of the present embodiment is not limited to the configuration shown in FIG.

<Film forming device>
The film forming apparatus 60 includes a gas cylinder 55, a transfer pipe 56, a nozzle 52, a base 63, and a film forming chamber 51. The gas cylinder 55 is filled with a carrier gas for accelerating the fine particles 54 and spraying the fine particles 54 on the base material 53. One end of a transfer pipe 56 is connected to the gas cylinder 55. The carrier gas supplied from the gas cylinder 55 is supplied to the carrier pipe 56. The transport pipe 56 is provided with a mass flow controller 57, an aerosol generator 58, and a disintegrator 59 and a classifier 61 that can appropriately adjust the dispersion degree of the fine particles 54 in the transport gas, in order from the front side. Yes. The mass flow controller 57 adjusts the flow rate of the carrier gas supplied from the gas cylinder 55 to the carrier pipe 56. The fine particles 54 loaded in the aerosol generator 58 are dispersed in the carrier gas supplied from the mass flow controller 57 and conveyed to the crusher 59 and the classifier 61.

  The nozzle 52 is disposed such that an opening (not shown) faces the base material 53 on the base 63. The other end of the transport pipe 56 is connected to the nozzle 52. The carrier gas containing the fine particles 54 is injected to the base material 53 from the opening of the nozzle 52. The base material 53 is placed on the upper surface 72 of the base 63 so that one surface 73 of the base material 53 comes into contact therewith. Further, the other surface 71 (film forming surface) of the substrate 53 faces the opening of the nozzle 52. The fine particles 54 injected together with the carrier gas from the nozzle 52 collide with the film forming surface, and a composite film made of the fine particles 54 is formed. A vacuum pump 62 is connected to the film forming chamber 51 provided for film formation in a reduced pressure atmosphere, and the inside of the film forming chamber 51 is depressurized as necessary.

《Solar cell》
As shown in FIG. 1, the first embodiment of the solar cell of the present invention includes the above-described photoelectrode 9, hole transport layer 5, and counter electrode 6. Examples of the hole transport layer 5 and the counter electrode 6 of the present embodiment include a hole transport layer and a counter electrode used in conventional solar cells.

  Photoelectrons and holes generated in the perovskite compound that has absorbed light in the photoelectrode 9 diffuse in the light absorption layer 7. The holes are received by the counter electrode 6 through the hole transport layer 5 or directly if the hole transport layer 5 is not present, and move to the counter electrode (positive electrode) formed by the counter electrode 6. On the other hand, photoelectrons are received by the underlayer 3 or the block layer 2 and move to the working electrode (negative electrode) formed by the conductive substrate 1.

  In the solar cell 10, the hole transport layer 5 is not essential, but is preferably disposed on the surface of the light absorption layer 7. By arranging the hole transport layer 5 on the surface of the light absorption layer 7, preferably on the surface of the upper layer 4, the generation of reverse current is suppressed and the holes generated in the light absorption layer 7 are easily transported to the counter electrode. And the photoelectric conversion efficiency and voltage can be increased.

<< Solar Cell Manufacturing Method >>
1st embodiment of the manufacturing method of the solar cell of this invention is a manufacturing method of the solar cell provided with the photoelectrode and the counter electrode, Comprising: The process of obtaining the above-mentioned photoelectrode 9, The organic inorganic of the photoelectrode 9 And disposing a counter electrode 6 on the surface of the light absorption layer 7 containing a perovskite compound. The formation method of the counter electrode 6 is not specifically limited, For example, the method demonstrated later is mentioned.

  2nd embodiment of the manufacturing method of the solar cell of this invention is a manufacturing method of the solar cell provided with the photoelectrode and the counter electrode, Comprising: The process of obtaining the above-mentioned photoelectrode 9, The organic inorganic of the photoelectrode 9 A method for manufacturing a solar cell, comprising: a step of forming a hole transport layer 5 on a light absorption layer 7 containing a perovskite compound; and a step of disposing a counter electrode 6 on the hole transport layer 5. The formation method of the positive hole transport layer 5 is not specifically limited, For example, the method demonstrated later is mentioned.

  In the present embodiment, an arbitrary conductive layer may be inserted between the light absorption layer 7 and the hole transport layer 5. Further, an arbitrary conductive layer may be inserted between the hole transport layer 5 and the counter electrode 6. From the viewpoint of increasing the photoelectric conversion efficiency by reducing the internal resistance of the solar cell 10, it is preferable to form the hole transport layer 5 on the surface of the light absorption layer 7 and dispose the counter electrode 6 on the surface of the hole transport layer 5. .

<Formation of hole transport layer 5>
The material of the hole transport layer 5 is not particularly limited, and may be an organic material or an inorganic material. For example, a known material for the hole transport layer of a solar cell can be applied.
Examples of the organic material include Spiro-OMeTAD.
(2,2 ', 7,7'-tetrakis (N, N-di-p-methoxyphenilamine) -9,9'-spirobifluorene),
P3HT (Poly (3-hexylthiophene)), PTAA (polytriarylamine), etc. are mentioned.
Examples of the inorganic material include copper compounds such as CuI, CuSCN, CuO, and Cu ₂ O and nickel compounds such as NiO.

The formation method of the hole transport layer 5 is not particularly limited, and a known method can be applied. For example, the above material is dissolved or dispersed in a solvent that does not dissolve the perovskite crystal, and is applied to the surface of the light absorption layer 7. And a method of obtaining the hole transport layer 5 by drying.
By the above method, for example, the hole transport layer 5 having a thickness of 1 nm to 1000 nm can be formed.
When the thickness of the hole transport layer 5 is 1 nm or more, leakage current can be prevented by preventing contact between the light absorption layer 7 and the counter electrode 6.
When the thickness of the hole transport layer 5 is 1000 nm or less, holes can be sufficiently transported to the counter electrode 6.

<Formation of counter electrode 6>
When the surface of the hole transport layer 5 or the hole transport layer 5 is not provided, the method of forming the counter electrode 6 on the surface of the light absorption layer 7 is not particularly limited. For example, a counter electrode of a conventional solar cell is used. A known film forming method such as sputtering or vapor deposition can be applied.

  The material which comprises the counter electrode 6 is not specifically limited, For example, any 1 or more types of metal selected from the group which consists of gold | metal | money, silver, copper, aluminum, tungsten, nickel, and chromium is suitable.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited by these examples.

[Example 1]
A conductive glass substrate having an FTO film made of fluorine-doped SnO ₂ formed on the surface of the glass substrate was used. A solution of titanium diisopropoxide bis (acetylacetonate) dissolved in isopropanol (manufactured by Sigma-Aldrich) was sprayed on the surface of the FTO film by a known spray pyrolysis method to form a block layer made of titania having a thickness of 30 nm. Formed.

A raw material solution of N, N-dimethylformamide (DMF) containing 0.9 M concentration of lead iodide (PbI ₂ ) and 0.9 M concentration of methylammonium iodide (CH ₃ NH ₃ I) was prepared. In this raw material solution, anatase-type TiO ₂ particles having an average particle diameter of about 15 nm (manufactured by Nippon Aerosil Co., Ltd .; trade name: P15) were immersed, stirred gently for 15 minutes, and then taken out and dried to obtain a composition formula ( Raw material fine particles having organic-inorganic hybrid perovskite crystals composed of a perovskite compound represented by CH ₃ NH ₃ PbI ₃ ) adhered to the surface were obtained.

  By the aerosol deposition method (AD method), the above raw material fine particles were sprayed on the surface of the block layer to form a porous layer having a thickness of 300 nm composed of titania fine particles with perovskite crystals adhering to the surface in 1 minute.

  A chlorobenzene solution containing 0.07M spiro-OMeTAD was applied to the surface of the perovskite crystal layer by spin coating to form a 200 nm thick hole transport layer made of spiro-OMeTAD.

  A counter electrode having a thickness of 50 nm made of gold (Au) was formed on the surface of the hole transport layer by a known vapor deposition method.

  The structure shown in FIG. 1 in which conductive substrate 1 / blocking layer 2 / porous layer 3 containing a perovskite compound / hole transport layer 5 / counter electrode 6 are sequentially laminated by the above method (excluding the upper layer 4). ) Was obtained.

[Examples 2 to 10]
A photoelectrode and a solar cell were produced in the same manner as in Example 1 except that the fine particles comprising the N-type semiconductor or insulator shown in Table 1 (φ is the average particle size) were used as the fine particles constituting the raw material fine particles. .

[Examples 11 to 12]
By the same AD method as in Example 1, the above raw material fine particles were sprayed on the surface of the block layer to form a porous layer having a thickness of 300 nm composed of titania fine particles with perovskite crystals adhering to the surface in one minute.
Subsequently, N, N-dimethylformamide (DMF) containing 0.9 M concentration of lead iodide (PbI ₂ ) was applied onto the porous layer by spin coating, followed by drying at 70 ° C. for 30 minutes. Then, after being immersed in an isopropanol solution containing 0.04 M concentration of methylammonium iodide (CH ₃ NH ₃ I) for 20 seconds and then taken out, it was subjected to a drying treatment at 100 ° C. for 30 minutes, whereby the composition formula (CH ₃ An organic-inorganic hybrid perovskite crystal composed of a perovskite compound represented by NH ₃ PbI ₃ ) was inserted into the pores of the porous film and also formed on the surface of the porous film.

  As shown in FIG. 1, the conductive substrate 1 / block layer 2 / porous layer 3 containing a perovskite compound / perovskite crystal layer / hole transport layer 5 / counter electrode 6 as the upper layer 4 are sequentially laminated by the above method. A solar cell 10 of Example 1 having a structure was obtained.

[Comparative Example 1]
As in Example 1, a 30 nm thick block layer made of titania was formed on the surface of the FTO substrate.
Next, a dispersion obtained by dispersing anatase TiO ₂ particles having an average particle size of about 15 nm (manufactured by Nippon Aerosil Co., Ltd .; trade name: P15) in isopropanol was applied onto the block layer by a spin coating method and dried. The formed coating film was baked at 500 ° C. for 60 minutes to form a porous layer made of titania fine particles having a thickness of 300 nm.
Subsequently, N, N-dimethylformamide (DMF) containing 0.9 M concentration of lead iodide (PbI ₂ ) was applied onto the porous layer by spin coating, followed by drying at 70 ° C. for 30 minutes. Then, after being immersed in an isopropanol solution containing 0.04 M concentration of methylammonium iodide (CH ₃ NH ₃ I) for 20 seconds and then taken out, it was subjected to a drying treatment at 100 ° C. for 30 minutes, whereby the composition formula (CH ₃ An organic-inorganic hybrid perovskite crystal layer made of a perovskite compound represented by NH ₃ PbI ₃ ) was formed on the surface and inside of the porous film.
Further, a hole transport layer and a counter electrode were formed in this order by the same method as in Example 1.

  As shown in FIG. 1, the conductive substrate 1 / block layer 2 / porous layer 3 containing a perovskite compound / perovskite crystal layer / hole transport layer 5 / counter electrode 6 as the upper layer 4 are sequentially laminated by the above method. A solar cell 10 of Example 1 having a structure was obtained.

[Comparative Examples 2 to 4]
A photoelectrode and a solar cell were produced in the same manner as in Comparative Example 1 except that the fine particles comprising the N-type semiconductor or insulator shown in Table 1 (φ is the average particle size) were used as the fine particles forming the porous layer. .

[Comparative Examples 5 to 8]
Comparative Examples 2 to 4 except that the fine particles comprising the N-type semiconductor or insulator shown in Table 1 (φ is the average particle size) were used as the fine particles forming the porous layer, and the firing temperature was changed to 150 ° C. A photoelectrode and a solar cell were prepared in the same manner as described above.

  In order to evaluate the current-voltage characteristics of the produced solar cell, the short circuit current Isc, the open circuit voltage Voc, the fill factor FF, and the photoelectric conversion efficiency Eff were measured using a solar simulator (AM1.5). The results are shown in Table 2.

  In the above results, Example 1 and Comparative Example 1 and Comparative Example 5, Example 2 and Comparative Example 2 and Comparative Example 6, Example 7 and Comparative Example 3 and Comparative Example 7 and Example using the same raw material fine particles In the test group of any combination of No. 8 and Comparative Example 4 and Comparative Example 8, the example in which the raw material fine particles to which the perovskite crystals were attached was used and the porous film (underlayer) was formed by the AD method was used. The photoelectric conversion efficiency was excellent.

  In Examples 1 to 12, the formation site of the perovskite crystal is the surface of the raw material fine particles before film formation. Thus, it is one of the reasons why the power generation performance of the photoelectrode of the example is improved by having a perovskite crystal that is crystallized in a different formation field from the surface of the porous film made of conventional fired fine particles. It is thought that.

  Further, in Examples 11 to 12 which are particularly excellent in photoelectric conversion efficiency, the formation field of the perovskite crystal added later is a porous film (underlayer) to which the perovskite crystal already formed by the AD method is attached. It is presumed that this porous film exhibited some preferable action that is difficult to obtain from a porous film obtained by conventional baking as a crystal formation field of a perovskite compound.

  In addition, when Examples 1 to 10 and Examples 11 to 12 are compared, a perovskite crystal is inserted later into the porous film that is the underlayer, and the perovskite crystal is also formed on the surface of the porous film. Examples 11-12 in which the upper layer formed is superior in photoelectric conversion efficiency. One reason for this is that the total amount of perovskite crystals has increased.

Since the underlayer can be formed at room temperature in the method for producing a photoelectrode of the present invention, the substrate having low heat resistance, which could not be used in the conventional method for forming a film that requires a baking step, is used. Can also be formed. Furthermore, since the underlayer can be formed in a short time (for example, 1 minute) according to the AD method, mass production by a roll-to-roll method is possible using a resin sheet as a base material.
In addition, in the case of forming a film by the conventional spin coating method and low temperature baking (Comparative Examples 5 to 8), it is possible to use a substrate having a relatively low heat resistance, but there is a problem that power generation performance is deteriorated and a large amount There is a problem that a relatively long baking time is unsuitable for production.

  The configurations and combinations thereof in the embodiments described above are examples, and the addition, omission, replacement, and other modifications of the configurations can be made without departing from the spirit of the present invention. Further, the present invention is not limited by each embodiment, and is limited only by the scope of the claims.

  The method for producing a photoelectrode of the present invention is widely applicable in the field of solar cells.

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Block layer, 3 ... Underlayer, 4 ... Upper layer, 5 ... Hole transport layer, 6 ... Counter electrode, 7 ... Light absorption layer, 8 ... Base material, 9 ... Photoelectrode, 10 ... Sun Battery: 51 ... Film forming chamber, 52 ... Nozzle, 53 ... Base material, 54 ... Composite fine particle, 55 ... Cylinder, 56 ... Transport pipe, 57 ... Mass flow controller, 58 ... Aerosol generator, 59 ... Crusher, 60 DESCRIPTION OF SYMBOLS ... Film forming apparatus, 61 ... Classifier, 62 ... Vacuum pump, 63 ... Base, 71 ... Film forming surface, 72 ... Mounting surface (upper surface) of base, 73 ... Surface opposite to film forming surface

Claims (11)

A photoelectrode comprising a base material having conductivity, a base layer laminated on the base material, and a light absorption layer containing an organic / inorganic perovskite compound formed at least inside the surface and the inside of the base layer A manufacturing method of
A method for producing a photoelectrode comprising a step of forming the underlayer by spraying at least one of N-type semiconductor fine particles and insulator fine particles to which the organic / inorganic perovskite compound is adhered to the base material. _{2. The} method for producing a photoelectrode according to claim 1, wherein the N-type semiconductor fine particles are fine particles comprising at least one selected from ZnO, TiO ₂ and SnO. The method for producing a photoelectrode according to claim 1, wherein the insulating fine particles are fine particles comprising at least one selected from Al ₂ O ₃ , ZrO ₂ and MgO.   The method for producing a photoelectrode according to any one of claims 1 to 3, wherein an average particle diameter of the N-type semiconductor fine particles and the insulating fine particles is 10 nm to 70 nm. The method for producing a photoelectrode according to any one of claims 1 to 4, wherein the organic / inorganic perovskite compound is represented by the following composition formula (I).
ABX ₃ (I)
[Wherein, A represents an organic cation, B represents a metal ion, and X represents a halogen ion. ]   The photoelectrode manufactured by the method as described in any one of Claims 1-5. A method for producing a solar cell comprising the photoelectrode according to claim 6 and a counter electrode,
Obtaining the photoelectrode by the method according to any one of claims 1 to 5,
Disposing the counter electrode on the surface of the light absorption layer of the photoelectrode. A method for producing a solar cell comprising the photoelectrode according to claim 6, a hole transport layer, and a counter electrode,
Obtaining the photoelectrode by the method according to any one of claims 1 to 5,
Forming the hole transport layer on the light absorption layer of the photoelectrode;
And disposing the counter electrode on the hole transport layer.   The method for manufacturing a solar cell according to claim 8, wherein the hole transport layer is formed on a surface of the light absorption layer, and the counter electrode is disposed on the surface of the hole transport layer.   A solar cell comprising the photoelectrode according to claim 6 and a counter electrode.   The solar cell manufactured by the method as described in any one of Claims 7-9.

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