JP6765658B2 - A pressed molded product containing particles of a metal composite anion compound and its use, and a method for producing the pressed molded product. - Google Patents

Description

The present invention relates to a pressed molded product containing particles of a metal composite anion compound, its use, and a method for producing the pressed molded product. The pressed molded product is used, for example, for converting solar energy into electrical energy or chemical energy, specifically, a photocatalyst, a photoelectrode, or solar energy that obtains hydrogen as chemical energy by photodecomposing water. It is useful as a material for constituting an optical electrode (solar cell, optical sensor, etc.) that converts the energy into electric energy.

Typical metal compounds represented by bismuth composite anion compounds (BiXY (X = Group 16 element anion, Y = Group 17 element anion)) are
(1) It has a band gap that can respond to visible light.
(2) The band gap can be adjusted by the halogen composition constituting the material.
(3) May have excellent semiconductor properties,
For these reasons, it is attracting attention as a promising photoelectrode material for photoenergy conversion.

When a dense thin film made of a bismuth composite anion compound is formed directly from a raw material solution (including a mode of fixing it on a substrate at the same time as formation), the heating temperature required for crystallization is the decomposition temperature of the material. It is not easy because it is very close.

On the other hand, the particles of the material can be prepared relatively easily, and when the particles are fixed on the base material, it is possible to have a high degree of freedom in morphology.

Scientific Repots 2016, 6, 32664.

However, as suggested in Non-Patent Document 1, in a thin film formed from particles of a typical metal compound as a raw material, the intergranular resistance between the particles in the thin film is large and the charge transfer efficiency is lowered, so that the performance of electrodes and the like is improved. The problem is that it interferes with the above.

Therefore, development of a measure for reducing the grain boundary resistance of a molded product made from particles, which can be prepared relatively easily and has a high degree of morphological freedom when fixed on a substrate. Is desired.

The present invention has been completed in order to solve the problems of the prior art, and provides a measure for reducing the grain boundary resistance between particles when a molded product is formed from particles of a typical metal compound as a raw material. The main purpose is.

As a result of diligent research to achieve the above object, the present inventors have conducted press-molding of a pressed raw material containing particles of a specific metal composite anion compound to produce a pressed molded product between particles. We have found that the binding between particles can be promoted and the intergranular resistance between particles can be effectively reduced, and the present invention has been completed.

That is, the present invention relates to a pressed molded product containing particles of the following metal composite anion compound, its use, and a method for producing the pressed molded product.
1. 1. The following general formula (1) composed of cation A, anion X and anion Y:
AXY (1)
A pressed molded product containing particles of a metal composite anion compound represented by.
(1) 96 to 100 mol% of the cation A is a Group 15 elemental cation.
(2) The anion X is a group 16 element anion, and the amount thereof is 35 to 65 mol% of the total amount of the anion.
(3) The anion Y is a Group 17 elemental anion, and the amount thereof is 35 to 65 mol% of the total amount of the anion.
(4) The crystallite diameter of the particles is 28 nm or more,
(5) The difference in thickness in the width range of 10 μm in the cross section of the pressed molded product in the pressing direction is within 1 μm.
A pressed molded product characterized by this.
2. Item 2. The pressure-molded article according to Item 1, wherein the amount of the organic molecular cation in the cation A is less than 4 mol%.
3. 3. Item 3. The pressed molded product according to Item 1 or 2, wherein 98 to 100 mol% of the cation A is a Group 15 elemental cation.
4. Item 3. The pressed molded product according to any one of Items 1 to 3, wherein the Group 15 elemental cation is a bismuth cation.
5. Item 2. The pressed molded product according to any one of Items 1 to 4, wherein the amount of the anion X is 40 to 60 mol% of the total amount of the anion.
6. Item 2. The pressed molded product according to any one of Items 1 to 5, wherein the Group 16 element anion is an anion of an element from the third period of the periodic table.
7. Item 2. The pressed molded product according to any one of Items 1 to 6, wherein the Group 16 element anion is a sulfur anion.
8. Item 2. The pressed molded product according to any one of Items 1 to 7, wherein the amount of the anion Y is 40 to 60 mol% of the total amount of the anion.
9. Item 2. The pressed molded product according to any one of Items 1 to 8, wherein the group 17 element anion is an anion of an element from the 4th period of the periodic table.
10. Item 2. The pressed molded product according to any one of Items 1 to 9, wherein the Group 17 element anion is a bromine anion or an iodine anion.
11. Item 2. The pressed molded product according to any one of Items 1 to 5, 8 to 10, wherein the metal composite anion compound is BiOI.
12. Item 2. The pressed molded product according to any one of Items 1 to 10, wherein the metal composite anion compound is BiSBr or BiSI.
13. Item 2. The pressed molded product according to any one of Items 1 to 12, wherein the crystal structure of the particles is orthorhombic.
14. Item 12. The pressed molded product according to Item 12, wherein the crystal structure of the particles is PDF: 00-043-0652.
15. Item 12. The pressed molded product according to Item 14, wherein the orientation ratio (110) / (002) between the (110) crystal plane and the (002) crystal plane of the metal composite anion compound is 2.0 or more.
16. Item 12. The pressed molded product according to Item 12, wherein the crystal structure of the particles is PDF: 01-075-1811.
17. Item 16. The pressed molded product according to Item 16, wherein the orientation ratio (110) / (121) of the (110) crystal plane to the (121) crystal plane of the metal composite anion compound is 1.0 or more.
18. Item 2. The pressed molded product according to Item 11, wherein the crystal structure of the particles is PDF: 00-010-0445.
19. Item 2. The pressed molded product according to Item 18, wherein the orientation ratio (110) / (200) between the (110) crystal plane and the (200) crystal plane of the metal composite anion compound is 15 or more.
20. Item 2. The pressed molded product according to any one of Items 1 to 19, wherein the crystal phase of the particles is a single crystal phase.
21. The pressed molded product according to any one of Items 1 to 20, which is in the form of a thin film.
22. Item 2. The pressed molded product according to Item 21, wherein the thin film has a film thickness of 0.5 to 10.0 μm.
23. The pressed molded product according to any one of Items 1 to 22, which is an n-type semiconductor.
24. Item 2. The pressed molded product according to any one of Items 1 to 23 above, which is in contact with a conductive material.
25. Item 2. The pressure-molded article according to Item 24, wherein the conductive material is a metal.
26. Item 2. The pressure-molded article according to Item 25, wherein the conductive material is copper or molybdenum.
27. Item 2. The pressed molded product according to any one of Items 1 to 23 above, which is in contact with a p-type semiconductor.
28. Item 2. The pressed molded product according to Item 27, wherein the p-type semiconductor is an inorganic material.
29. Item 27. The press-molded product according to Item 27, wherein the p-type semiconductor is copper halide, copper sulfide, copper oxide or molybdenum oxide.
30. Item 2. The pressed molded product according to Item 27, wherein the p-type semiconductor is an organic semiconductor.
31. Use of the pressed molded product according to any one of Items 1 to 30 above as a semiconductor material.
32. Use of the pressed molded product according to any one of Items 1 to 30 above as a solar cell material.
33. Use of the pressed molded product according to any one of Items 1 to 30 above as a light absorption layer of a solar cell.
34. Use of the pressed molded product according to any one of Items 1 to 30 above as an optical sensor.
35. Use of the pressed molded product according to any one of Items 1 to 30 above as a light emitting material.
36. The following general formula (1) composed of cation A, anion X and anion Y:
AXY (1)
A method for producing a pressed molded product by press molding a pressed raw material containing particles of a metal composite anion compound represented by.
(1) 96 to 100 mol% of the cation A is a Group 15 elemental cation.
(2) The anion X is a group 16 element anion, and the amount thereof is 35 to 65 mol% of the total amount of the anion.
(3) The anion Y is a Group 17 elemental anion, and the amount thereof is 35 to 65 mol% of the total amount of the anion.
(4) The pressing molding is performed by applying a pressing pressure of 0.1 MPa to 20 MPa for 1 second to 20 hours in an atmospheric pressure of 0.01 Pa to 2 MPa under a temperature condition of 0 to 300 ° C.
A method for producing a pressed molded product.
37. Item 3. The production method according to Item 36, which is the method for producing a pressed molded product according to any one of Items 1 to 30.
38. Item 3. The manufacturing method according to Item 36 or 37, wherein the pressing molding is performed in a state where the pressed raw material is sandwiched between inorganic plate materials.
39. The production method according to any one of Items 36 to 38 above, wherein the temperature condition is 20 to 200 ° C.
40. Item 6. The production method according to any one of Items 36 to 39, wherein the pressing pressure is 0.6 MPa to 10 MPa.
41. The production method according to any one of Items 36 to 40 above, wherein the time for applying the pressing pressure is 10 seconds to 10 hours.
42. The production method according to any one of Items 36 to 41 above, wherein the pressure molding is performed so as to form a thin film.

The pressed molded product of the present invention is a pressed molded product of a pressed raw material containing particles of a specific metal composite anion compound, and in addition to being easy to prepare the raw material particles, the pressed molded product is bonded between the particles. Is promoted, so that the intergranular resistance between the particles contained in the pressed molded product is effectively reduced. The reduction of the intergranular resistance between the particles brings about, for example, an improvement in the transfer characteristics of photoexcited electrons and an improvement in photoelectrochemical characteristics when the pressed molded product is used as a semiconductor material.

Such a pressed molded product of the present invention is, for example, in the form of a thin film, and is used for converting solar energy into electrical energy or chemical energy in a mode of contacting with a conductive material, a p-type semiconductor, or the like, if necessary. Specifically, it is useful as a material for constituting photocatalysts and photoelectrodes that obtain hydrogen as chemical energy by photodecomposing water, and photoelectrodes (solar cells, optical sensors, etc.) that convert solar energy into electrical energy. Is. In addition, it can be applied to magnetic materials and optical materials.

It is a top surface SEM image of a BiSI electrode (before hot press (HP) treatment). It is a cross-sectional SEM image of a BiSI electrode (before HP treatment). It is a top surface SEM image of a BiSI electrode (after HP treatment). It is a cross-sectional SEM image of a BiSI electrode (after HP treatment). It is a figure which shows the photoelectrochemical property before and after HP treatment of a BiSI electrode. It is a top surface SEM image of a BiSBr electrode (before HP treatment). It is a cross-sectional SEM image of a BiSBr electrode (before HP treatment). It is a top surface SEM image of a BiSBr electrode (after HP treatment). It is a cross-sectional SEM image of a BiSBr electrode (after HP treatment). It is a figure which shows the photoelectrochemical property before and after HP treatment of a BiSBr electrode. It is a top surface SEM image of a BiOI electrode (before HP treatment). It is a cross-sectional SEM image of a BiOI electrode (before HP treatment). It is a top surface SEM image of a BiOI electrode (after HP treatment). It is a cross-sectional SEM image of a BiOI electrode (after HP treatment). It is a figure which shows typically the relationship between the direction of light irradiation and the diffusion distance of an electron to a substrate in the measurement of a photoelectrochemical property. It is a figure which shows the direction of light irradiation of a BiSI electrode (before and after HP treatment) and the relationship between before and after HP treatment, and the reduction rate of a photoelectrochemical property. It is a figure which shows the direction of light irradiation of a BiSBr electrode (before and after HP treatment), and the relationship between before and after HP treatment, and the reduction rate of a photoelectrochemical property. It is a figure which shows the direction of light irradiation of a BiOI electrode (before and after HP treatment) and the relationship between before and after HP treatment, and the reduction rate of a photoelectrochemical property. It is a schematic diagram which shows the crystal structure of BiOX (however, X of FIG. 19 shows a group 17 element anion. Source: Scientific Repots 2016, 6, 32664.). It is a top photograph of the BISI pressed molded product transferred to the back surface of the copper plate. It is an SEM image of the upper surface of the BISI pressed molded product transferred to the back surface of the copper plate. It is a top photograph of the BISI pressed molded product transferred to the back surface of the molybdenum plate. It is an SEM image of the upper surface of the BISI pressed molded product transferred to the back surface of the molybdenum plate. It is a top surface SEM image of a BISI pressed molded product transferred to the back surface of a CuOx-Cu plate.

1. 1. Press-molded article of the present invention The press-molded article of the present invention is composed of the following general formula (1): anion A, anion X and anion Y:
AXY (1)
A pressed molded product containing particles of a metal composite anion compound represented by.
(1) 96 to 100 mol% of the cation A is a Group 15 elemental cation.
(2) The anion X is a group 16 elemental anion, and the amount thereof is 35 to 65 mol% of the total amount of the anion.
(3) The anion Y is a Group 17 elemental anion, and the amount thereof is 35 to 65 mol% of the total amount of the anion.
(4) The crystallite diameter of the particles is 28 nm or more,
(5) The difference in thickness in the width range of 10 μm in the cross section of the pressed molded product in the pressing direction is within 1 μm.
It is characterized by that.

The pressed molded product of the present invention having the above characteristics is a pressed molded product of a pressed raw material containing particles of a specific metal composite anion compound. In addition to being easy to prepare the raw material particles, the pressed molded product is a particle. Since the binding between the particles is promoted, the intergranular resistance between the particles contained in the pressed compact is effectively reduced. The reduction of the intergranular resistance between the particles brings about, for example, an improvement in the transfer characteristics of photoexcited electrons and an improvement in photoelectrochemical characteristics when the pressed molded product is used as a semiconductor material.

The above-mentioned "improvement of photoelectrochemical properties" can be evaluated by, for example, an increase in the photocurrent density at the time of light irradiation in the potential-current curve in the electrolytic solution described later. Further, "improvement of transfer characteristics of photoexcited electrons" means, for example, a case where a pressed molded product described later is fixed on a transparent electrode and light is irradiated from the transparent electrode side and a case where light is irradiated from the pressed molded product side. It can be evaluated from the comparison of photoelectrochemical properties. It is preferable to observe a decrease in grain boundary resistance from the improvement of photoelectrochemical properties or transfer characteristics of photoexcited electrons, and a decrease in grain boundary resistance is observed from the improvement of photoelectrochemical properties and transfer characteristics of photoexcited electrons. Is even more preferable. Further, the above-mentioned "reduction of grain boundary resistance between particles" is observed, for example, in the case of an electrode composed of a thin film, the effect of the macroscale range from the vicinity of the substrate to the surface of the material on the opposite bank and the effect mainly in the vicinity of the substrate. It means both micro-scale and so on.

Although the inventors do not want to be bound by theory, it is presumed that the above-mentioned "decrease in grain boundary resistance" is caused by, for example, the following mechanism.

That is, AXY (96 to 100 mol% of cation A is a group 15 element cation, anion X is a group 16 element anion, the amount is 35 to 65 mol% of the total amount of anions, and anion Y is the 17th. Packing of particles in a press-molded product by press-molding a pressed raw material containing particles of a metal composite anion compound represented by a group element anion, the amount of which is 35 to 65 mol% of the total amount of anions). It is presumed that (for example, the density of particles in a unit volume) is improved, the crystal structure of the particles is changed (for example, the crystal orientation is changed), and the like, and as a result, the intergranular resistance between the particles is reduced.

For example, a change in the packing of particles in a pressed molded product is observed by a change in crystal orientation and a change in the morphology of the molded product before and after pressing. Specifically, the change in the form of the molded product is a flattening of the surface subjected to the pressure molding treatment, a cross-sectional view of the molded product, or the like, and can be observed with an electron microscope (for example, SEM or the like). Further, the change in the crystal structure can be evaluated by XRD or the like, and the change in the orientation can be evaluated from the ratio of the diffraction peaks on a specific orientation plane ((001) plane, (200) plane, etc.). it can.

Such a pressed molded product of the present invention is, for example, in the form of a thin film, and is used for converting solar energy into electrical energy or chemical energy in a mode of contacting with a conductive material, a p-type semiconductor, or the like, if necessary. Specifically, it is useful as a material for constituting photocatalysts and photoelectrodes that obtain hydrogen as chemical energy by photodecomposing water, and photoelectrodes (solar cells, optical sensors, etc.) that convert solar energy into electrical energy. Is. In addition, it can be applied to magnetic materials and optical materials.

The particles of the metal composite anion compound contained in the pressed molded product of the present invention are composed of the following general formula (1): anion A, anion X and anion Y:
AXY (1)
It is a compound indicated by.

96 to 100 mol% of the cation A is a Group 15 elemental cation, and the content of the Group 15 elemental cation is preferably 98 to 100 mol%, more preferably 99 to 100 mol%. The Group 15 element cation is not limited, and examples thereof include bismuth (Bi) cation and antimony (Sb) cation, and bismuth cation is preferable among them. Since the bismuth cation has a low melting point and low hardness among the group 15 element cations, it is considered that the bismuth cation easily promotes the binding between particles by pressure molding and easily reduces the intergranular resistance between the particles, especially to the human body. It is also preferable from the viewpoint of less harm.

The cation A may contain an organic molecular cation in addition to the group 15 elemental cation, but the content of the organic molecular cation is preferably less than 4 mol% from the viewpoint of stability such as heat resistance. Among them, 3 mol% or less is preferable, 1 mol% or less is more preferable, 0.1 mol% or less is further preferable, and 0.01 mol% or less is most preferable. The organic molecular cation content can be measured by, for example, TG-MAS.

The anion X is a group 16 elemental anion, and the amount thereof is 35 to 65 mol% of the total amount of the anion. Among them, the amount of anion X is preferably 40 to 60 mol% of the total amount of anions.

The group 16 element anion is not limited, and examples thereof include an oxygen (O) anion, a sulfur (S) anion, a selenium (Se) anion, and a tellurium (Te) anion. Among these, since it has a high covalent bond and has a relatively large ionic radius, it is easy to promote the binding between particles by pressure molding, and it is easy to reduce the intergranular resistance between particles. It is preferably an anion of the element after 3 cycles. For example, sulfur anion, selenium anion, tellurium anion and the like are preferable, and among them, sulfur anion and selenium anion are more preferable, and sulfur anion is most preferable from the viewpoint of less harm to the human body.

The anion Y is a group 17 elemental anion, and the amount thereof is 35 to 65 mol% of the total amount of the anion. Among them, the amount of anion Y is preferably 40 to 60 mol% of the total amount of anions.

The group 17 element anion is not limited, but is preferably an anion of an element from the 4th period onward in the periodic table of the new IUPAC, and examples thereof include a bromine (Br) anion and an iodine (I) anion. Of these, iodine anion is more preferable.

The crystallite diameter of the particles of the metal composite anion compound may be 28 nm or more. From the viewpoint of being advantageous in reducing defects in the extruded product, the crystallite diameter of the particles of the metal composite anion compound is preferably 40 nm or more. Further, from the viewpoint of being advantageous in forming an extruded molded product precisely, it is preferably 1 μm or less, and more preferably 500 nm or less.

The crystal structure of the particles is preferably orthorhombic, and is preferably any of PDF: 00-043-0652, 01-075-1811, 00-010-0445. Further, the crystal phase of the particles is preferably a single crystal phase.

More specifically, when the crystal structure of the particles is PDF: 00-043-0652, the orientation ratio of the (110) crystal plane to the (002) crystal plane of the metal composite anion compound (110) / (002). Is preferably 2.0 or more, more preferably 2.2 or more, and even more preferably 2.4 or more. In the case of the above PDF: 01-075-1811, the orientation ratio (110) / (121) of the metal composite anion compound between the (110) crystal plane and the (121) crystal plane is preferably 1.0 or more. .. Further, in the case of the above PDF: 00-010-0445, the orientation ratio (110) / (200) between the (110) crystal plane and the (200) crystal plane of the metal composite anion compound is preferably 15 or more. , 18 or more is more preferable, and 20 or more is further preferable. In the case of PDF: 00-043-0652, BiSI is representative, in the case of PDF: 01-075-1811, BiSBr is applicable, and in the case of PDF: 00-010-0445, BiOI is representative. However, it is not limited to these.

Among the above, PDF: 00-043-0652 or 01-075-1811 is preferable from the viewpoint that it is advantageous that the ab-axis orientation is strengthened by pressure molding. By increasing the ab-axis orientation, for example, when the conductive material and the pressed molded product of the present invention are in contact with each other, the conductivity of the A cation and the group 16 element anion in the pressed molded product by the unit. It is easier to form connections to the sex material, and electron transfer within the Bi-16 group element anion unit may be more advantageous than electron transfer from the Bi-16 group element anion unit to the halogen anion. Due to the property, the diffusion of electrons and holes into the conductive material becomes advantageous, the grain boundary resistance between the particles is reduced, and / or the efficiency of taking out electrons is improved. Specifically, it has the effect of improving the photoelectrochemical properties and / or the transfer characteristics of photoexcited electrons.

Among the above, PDF: 00-010-0445 is preferable from the viewpoint that it is advantageous that the c-axis orientation is strengthened by press molding. The stronger c-axis orientation of the PDF: 00-010-0445 material is advantageous for making the packing of the pressed compact more dense, and thus is advantageous for improving the movement characteristics of photoexcited electrons. Further, when the pressed molded product is provided on the base material, the units of the A cation and the X anion in the pressed molded product are likely to be continuously present in the horizontal direction with the base material, so that the unit with the base material is easily present. It is advantageous for the diffusion of electrons and / or holes in the horizontal direction. Therefore, it becomes excellent in confinement of electrons and / or holes, and can be suitably used as a light emitting material or the like.

Specific examples of the metal composite anion compound include at least one such as BiOI, BiSI, BiSeI, BiOBr, BiSBr, BiSeBr, BiOCl, BiSCl, and BiSeCl. Among these, at least one of BiOI, BiSI, BiOBr, BiSBr and the like is preferable, and at least one of BiSI and BiSBr is most preferable. The particles of these metal composite anion compounds can be synthesized, for example, by a known spray pyrolysis method, vapor phase growth method, solvothermal method in an aqueous solvent or an organic solvent, or the like.

The particle size of the metal composite anion compound is not limited, but the average particle size is preferably 0.01 to 10 μm, more preferably 0.1 to 1 μm. The average particle size in the present specification is a value measured by observation by SEM.

The surface of the pressed molded product of the present invention is preferably flattened, and the difference in thickness in the width range of 10 μm in the cross section of the pressed molded product in the pressing direction is within 1 μm. Among these, the difference in thickness is preferably 500 nm or less, more preferably 200 nm or less, and even more preferably 100 nm or less. The difference in thickness in the present specification is a value measured by SEM observation.

The form of the press-molded product of the present invention is not limited as long as it is obtained by press-molding a raw material (pressed raw material) containing particles of a predetermined metal composite anion compound, but it is applied to various uses such as a photoelectrode. Considering this, the form of a thin film is preferable. The film thickness of the thin film is preferably 0.5 to 10.0 μm, and more preferably 0.9 to 8.0 μm. The film thickness of the thin film in the present specification is a value measured by cross-sectional SEM observation.

In the pressed molded product of the present invention, it is particularly preferable that the particles of the metal composite anion compound are BiSI or BiSBr from the viewpoint that it is advantageous that the ab axis orientation is strengthened by the pressed molding. By increasing the ab-axis orientation, for example, when the conductive material and the pressed compact of the present invention are in contact with each other, the conductive material is formed by a unit of a bismuth cation and a sulfur anion in the pressed compact. It is possible that the electron transfer within the Bi-16 group element anion unit is more advantageous than the electron transfer from the Bi-16 group element anion unit to the halogen anion. , The diffusion of electrons and holes toward the substrate becomes advantageous, the grain boundary resistance between particles is reduced, and / or the efficiency of taking out electrons is improved. Specifically, it has the effect of improving the photoelectrochemical properties and / or the transfer characteristics of photoexcited electrons.

BiOI is preferable from the viewpoint that it is advantageous to increase the c-axis orientation by pressing molding. The stronger c-axis orientation of the BiOI material is advantageous for making the packing of the pressed compact more dense, and thus is advantageous for improving the movement characteristics of photoexcited electrons. Further, when the pressure-molded product is provided on the base material, the unit of the bismuth cation and the oxygen anion in the pressure-molded product tends to be continuously present in the horizontal direction with the base material. It is advantageous for the diffusion of electrons or holes in the horizontal direction.

The application of the pressed molded product of the present invention is not limited, but since the binding of the metal composite anion compound between the particles is promoted in the pressed molded product, the intergranular resistance between the particles contained in the pressed molded product is increased. It has been effectively reduced. Therefore, it is preferable to use it as a semiconductor material (n-type semiconductor). Examples of the semiconductor material include a material having an energy difference between the upper end of the valence band and the lower end of the conduction band.

The pressed molded product of the present invention can also be used for other purposes. Specifically, it is a material that conducts electrons, holes, or ions, a material that utilizes the generation of photoexcited carriers by light absorption, a material that utilizes light emission due to its recombination, and the like, and more specifically, the sun. Materials for battery materials, light absorption layers of solar cells, photosensors, photocatalysts, etc., as well as light emitting materials, ion conductive materials, conductive materials, piezoelectric elements, power devices and the like. The ion refers to a cation or anion constituting each material. Among these uses, the pressed molded product of the present invention is preferably a compound for the light absorption layer of a solar cell from the viewpoint that the energy of photons contained in sunlight can be utilized. Further, from the viewpoint that light of a specific wavelength can be used, it is preferable to use it as an optical sensor.

Since the pressed molded product of the present invention has excellent light absorption characteristics, it is preferable to apply it as a solar cell (particularly, a solar cell using the pressed molded product of the present invention in the light absorption layer), and further, a photocurrent By improving at least one of the density, open circuit voltage, and fill factor, the solar conversion efficiency can be further improved.

The pressed molded product of the present invention is preferably in contact with an electron transporting material (so-called conductive material) from the viewpoint of excellent anisotropy of carrier movement. The electron transporting material referred to here is a semiconductor or the like in which the effective mass of electrons is smaller than that of holes, and is a material or the like that is advantageous for transporting electrons. When the pressed molded product of the present invention is a thin film, it is preferable that the electron transporting material in contact is also a thin film from the viewpoint that increasing the contact area is advantageous for the movement of electrons.

Examples of the electron transport material include an organic substance and an inorganic substance. However, the electron transport material preferably contains an inorganic substance from the viewpoint of increasing the strength combined with the pressed molded product of the present invention due to its high strength. From the viewpoint that the physical properties can be adjusted relatively easily, the metal compound is more preferable. From the viewpoint of being relatively easy to manufacture and store in the atmosphere, the electron transport material is more preferably a metal oxide.

Specific examples of the metal oxide include, but are not limited to, titanium oxide, niobium oxide, tungsten oxide, tin oxide, aluminum oxide, silicon oxide, magnesium oxide, copper oxide, molybdenum oxide, and the like. Titanium oxide and niobium oxide are preferable from the viewpoint of small effective mass, titanium oxide is preferable from the viewpoint of abundant materials and low cost, and copper oxide and molybdenum oxide are preferable from the viewpoint of being able to be densely laminated with a metal composite anion compound. .. From the viewpoint of reducing defects such as pinholes in the electron transport material, it is preferable that the electron transport material is subjected to a treatment of adsorbing and reacting the precursor material. Specifically, it is preferable to perform a treatment (TiCl ₄ treatment) of adsorbing the titanium chloride species on the electron transport material and then hydrolyzing it to bind titanium oxide.

The pressed molded product of the present invention is preferably in contact with a hole transport material (so-called p-type semiconductor) from the viewpoint of excellent anisotropy of carrier movement. The hole transporting material referred to here is a semiconductor or the like in which the effective mass of holes is smaller than that of electrons, and is a material or the like that is advantageous for transporting holes. When the pressed molded product of the present invention is a thin film, it is preferable that the hole transporting material in contact is also a thin film from the viewpoint that increasing the contact area is advantageous for the movement of electrons. The hole transport material may contain an organic substance or an inorganic substance. However, from the viewpoint that the soft material makes it difficult to form film defects due to bending, the hole transport material preferably contains an organic substance, and is an organic substance. Specific examples include aggregates of organic molecules and organic polymers. More specifically, Spiro-OMeTAD, P3HT, PTAA, TPD, NPD, TCTA, etc. can be mentioned, and Spiro- can be increased in carrier density, can be advantageous for hole transport, and can increase electromotive voltage. OMeTAD is preferred. As the Spiro-OMeTAD, one that has been doped by mixing LiTFSI or an oxidizing material is preferable from the viewpoint of excellent conductivity.

2. Method for Producing Pressed Mold of the Present Invention The method for producing a pressed molded product of the present invention is composed of the following general formula (1):
AXY (1)
A method for producing a pressed molded product by press molding a pressed raw material containing particles of a metal composite anion compound represented by.
(1) 96 to 100 mol% of the cation A is a Group 15 elemental cation.
(2) The anion X is a group 16 element anion, and the amount thereof is 35 to 65 mol% of the total amount of the anion.
(3) The anion Y is a Group 17 elemental anion, and the amount thereof is 35 to 65 mol% of the total amount of the anion.
(4) The pressing molding is performed by applying a pressing pressure of 0.1 MPa to 20 MPa for 1 second to 20 hours in an atmospheric pressure of 0.01 Pa to 2 MPa under a temperature condition of 0 to 300 ° C.
It is characterized by that.

In the method for producing a pressed molded product of the present invention, particles of the metal composite anion compound represented by the above-mentioned general formula (1) are used as a raw material (pressed raw material), and the specific particles specified in (4) above are used. It is characterized in that it is pressed and molded under pressing conditions. Since the description of the particles of the metal composite anion compound is the same as described above, it is omitted here.

The pressing condition in the method for producing a pressed molded product of the present invention is to apply a pressing pressure of 0.1 MPa to 20 MPa for 1 second to 20 hours in an atmospheric pressure of 0.01 Pa to 2 MPa under a temperature condition of 0 to 300 ° C. Any material may be used as long as the material to be pressed is pressed and molded.

Among them, the temperature condition is preferably 20 to 200 ° C., the atmospheric pressure condition is preferably 0.1 Pa to 1 MPa, and the atmospheric pressure is more preferable. The pressing pressure condition is preferably 0.6 to 10 MPa, more preferably 2 to 8 MPa. The time condition for applying the pressing pressure is preferably 10 seconds to 10 hours, more preferably 1 minute or more and 5 hours or less. The atmospheric pressure is described as an absolute pressure. In the present invention, the temperature condition can be particularly low from 0 to 300 ° C. to a relatively low temperature (up to about 50 ° C.), so that on a flexible base material such as a plastic base material, which should avoid high temperature treatment It can also be applied to the application of forming a pressure molded product.

Although the press molding can be performed using a known press machine (for example, a known hot press machine), it is preferable to perform the press molding with the material to be pressed sandwiched between the inorganic plate materials. For example, in the case of producing electrodes and the like, the pressed raw material is deposited on an inorganic plate material such as an FTO base material by a known method such as an electrophoresis method, a paste (slurry) coating drying method, or a screen printing method. An embodiment in which an inorganic plate material such as a quartz plate is further placed on the plate material and the pressed raw material is sandwiched between the inorganic plate materials is press-molded.

In addition, in the case of forming the pressure-molded product on the FTO base material at the time of pressure-molding, an inorganic plate material such as a quartz plate may be placed and the pressure-molded raw material may be pressure-molded. A specific metal plate (a metal plate that can be a conductive material) such as a copper plate (which may contain copper oxide) or a molybdenum plate (which may contain molybdenum oxide) is sandwiched between the metal plate and the quartz plate and pressed together. , Or a specific metal plate (a metal plate that can be a conductive material) such as a copper plate (which may contain copper oxide) or a molybdenum plate (which may contain molybdenum oxide) as an inorganic plate material without installing a quartz plate or the like. The pressed molded product can be transferred to the metal plate by contacting the pressed raw material, and a laminate of the pressed molded product of the present invention and the conductive material can be simultaneously produced by pressure molding and transfer. Therefore, as the inorganic plate material in the present specification, it is possible to simultaneously produce a laminate of an inorganic plate material such as a quartz plate as a pressing means only and a pressed molded product by transfer during pressing, which can be a pressing means and a conductive material. Both metal plates (copper plate, molybdenum plate, etc.) are included.

Further, it is possible to form a semiconductor material, for example, copper oxide, copper sulfide, or molybdenum oxide such as a p-type semiconductor material, which is in close contact with the pressed molded product during the transfer, which is advantageous for charge separation by heterojunction. be able to. From the viewpoint of being able to transfer the pressed molded product precisely, a copper plate (which may contain copper oxide) and a molybdenum plate (which may contain molybdenum oxide) are preferable, and a copper plate (which may contain copper oxide) is most preferable. Further, in this transfer, from the viewpoint of being able to transfer precisely, the metal composite anion compound is preferably BiSI, BiSBr, BiOI, more preferably BiSI, BiSBr, and most preferably BiSI.

By press-molding while sandwiched between inorganic plate materials in this way, binding between particles can be promoted and grain boundary resistance between particles can be effectively reduced, and the press-molded product is used as, for example, a semiconductor material. In this case, effects such as improvement of the transfer characteristics of photoexcited electrons and improvement of photoelectrochemical characteristics can be obtained. On the other hand, in the case of press molding while sandwiched between resin sheets such as Teflon (registered trademark) sheet, which has a lower hardness than the metal composite anion compound, the metal composite anion compound is simultaneously removed when the resin sheet is removed after the press molding. It is not preferable because the particles may peel off. Therefore, it is preferable that the inorganic plate material has a hardness higher than that of the metal composite anion compound and is not flexible in itself. Further, in the present invention, by press-molding with a quartz plate or the like, the particles adhere to the FTO base material or the like as compared with the case where the particles of the metal composite anion compound are deposited on the FTO base material or the like by electrophoresis or the like. It can also enhance sex.

In the press molding, the press molding conditions may be appropriately adjusted according to the form of the press molded product obtained by the press molding, and the final press molding can have a high degree of freedom in form. For example, when the pressed molded product is applied to an application such as an electrode, it is preferable to perform the pressed molding so as to form a thin film. In that case, the pressure-molded product (thin film) may be pressure-molded so that the film thickness is about 0.5 to 10.0 μm, particularly 0.9 to 8.0 μm.

Hereinafter, the present invention will be specifically described with reference to test examples, but the present invention is not limited to the test examples.

The metal composite anion compound (BiOI particles, BiSBr particles and BiSI particles) used in the examples was prepared by the following procedure.
<BiOI particles>
3 mmol of Bi (NO ₃ ) · 5H ₂ O was dissolved in 2.5 mL of CH ₃ COOH.

Was also dissolved and _CH 3 COONa of NaI and 6mmol of 3mmol of _{H 2} O 37.5 mL. Both solutions were then mixed and stirred for 20 minutes.

Then, solvent removal by centrifugation and washing with water were repeated three times.

As a result, single-phase BiOI particles were prepared. According to XRD, the average particle diameter of the BiOI particles was 0.2 μm, and the crystallite diameter of the particles was 56 nm.
<BiSI particles>
0.99 ° C. In _{H 2} S stream of 60 mL / min for the BiOI particles were sulfide over 1 hour. As a result, single-phase BiSI particles were prepared. The average particle size of the BiSI particles was 0.2 μm, and the crystallite diameter of the particles was 70 nm.
<BiSBr particles>
3 mmol of Bi (NO ₃ ) · 5H ₂ O was dissolved in 2.5 mL of CH ₃ COOH.

Further, 3 mmol of NaBr and 6 mmol of CH ₃ COONa were dissolved in 37.5 mL of H ₂ O. Both solutions were then mixed and stirred for 20 minutes.

Then, solvent removal by centrifugation and washing with water were repeated three times. As a result, BiOBr particles were prepared.

0.99 ° C. In _{H 2} S stream of 60 mL / min for the BiOBr particles were sulfide over 1 hour. As a result, single-phase BiSBr particles were prepared. The average particle size of the BiSBr particles was 0.2 μm, and the crystallite diameter of the particles was 78 nm.

Test Example 1 (Preparation of BiSI / FTO electrode and evaluation of its characteristics)
(Preparation of BiSI / FTO electrode (before hot press (HP) treatment))
An Asahi Glass FTO substrate (25 mm × 25 mm × 2 mm) was prepared.

Then, a suspension in which a 2-propanol solution of 10 mg / ml BiSI particles was suspended by sonication was prepared.

Then, 200 ml of the above suspension was added dropwise to the FTO substrate and dried. This dropping and drying treatment was repeated 3 times.

The particles were then removed with a dry cotton swab to ensure an exposed portion of the FTO substrate (9 mm x 25 mm). In addition, the portion from which the particles had been removed was wiped off with a cotton swab containing dilute hydrochloric acid.

Next, a BiSI / FTO electrode (before HP treatment) was prepared by heating on a hot plate at 50 ° C. for 20 minutes.

The upper surface SEM image of the BiSI / FTO electrode (before HP treatment) is shown in FIG. A cross-sectional SEM image of the electrode is shown in FIG.
(Preparation of BiSI / FTO electrode (after HP treatment))
Next, a quartz plate (25 mm × 25 mm × 2 mm) was placed on the BiSI / FTO electrode (before HP treatment), and the temperature was 50 ° C., atmospheric pressure atmospheric pressure, pressing pressure 5 MPa, and pressing time using a hot press device (manufactured by SINTO). Press molding was performed under the condition of 20 minutes. As a result, a BiSI / FTO electrode (after HP treatment) was produced.

The upper surface SEM image of the BiSI / FTO electrode (after HP treatment) is shown in FIG. A cross-sectional SEM image of the electrode is shown in FIG.
(Crystal structure of BiSI / FTO electrode (before and after HP treatment))
As a result of XRD measurement of the electrodes before and after the HP treatment, the crystallite diameter of BiSI was 70 nm, which was the same as that of the particles. Further, it was shown that the diffraction peak ratio of the (110) plane / (002) plane was increased from 1.9 to 2.4 by the HP treatment, and the orientation was ab-axis.
(Photoelectrochemical characteristics of BiSI / FTO electrodes (before and after HP treatment))
Next, the photoelectrochemical properties of the BiSI / FTO electrodes (before and after HP treatment) were examined under the conditions shown below.
-Electrolytic solution: 0.1 M NaI / acetonitrile-Scanning speed: 50 mV / s
・ Electrode area: 4 cm ²
-Light source: Solar simulator (100 mW / cm ² ) Intermittent irradiation every ^second The measurement results of photoelectrochemical characteristics are shown in FIG.
(Dependence of photoelectrochemical properties of BiSI / FTO electrodes (before and after HP treatment) on the light irradiation direction)
When investigating the photoelectrochemical properties, as schematically shown in FIG. 15, a large amount of light is absorbed in the vicinity of the side irradiated with light. Therefore, when light is irradiated from the BiSI side (Front Side), the light is emitted from the substrate side. Compared with the case of light irradiation (Back Side), the diffusion distance of many photoexcited electrons generated to the substrate is increased. That is, when light is irradiated from the Front Side, the photoelectrochemical properties are deteriorated.

Therefore, by comparing the reduction rates after the HP treatment, it is possible to evaluate the effect of the HP treatment on the movement characteristics of the photoexcited electrons. That is, if the reduction rate decreases before and after the HP treatment, it means that the electrons are transferred more efficiently in the material, and the movement characteristics of the photoexcited electrons are improved by the HP treatment. Can be evaluated as.

The measurement results of the light irradiation direction dependence of the photoelectrochemical properties are shown in FIG. 16 and Table 1 below.
(Consideration)
As is clear from the results of FIGS. 1 and 3, BiSI particles are deposited on the FTO electrode while maintaining their particle shape before the HP treatment, but after the HP treatment, one of the deposits (pressed raw material). The part was flattened, and in the flattened part, BiSI particles were bound to each other to the extent that the grain boundaries of the particles could not be seen in the SEM image. In addition, it was confirmed by EDX measurement that the composition of the flattened portion did not change as compared with that before flattening. Further, as is clear from the results of FIGS. 2 and 4, BiSI particles are coarsely deposited on the FTO substrate before the HP treatment (the film thickness of the sedimentary layer is 5 to 10 μm), but after the HP treatment, the sedimentary layer is deposited. Flattened and the film thickness decreased to 3 to 4 μm. From FIG. 4, it was found that the difference in thickness in the width range of 10 μm in the cross section of the pressed molded product in the pressing direction was within 1 μm. In addition, the results of XRD showed that the HP treatment resulted in ab-axis orientation, and the Bi-S unit in BiSI was oriented so as to be easily bonded to the substrate.

As is clear from the measurement results of the photoelectrochemical properties when the electrodes before and after the HP treatment in FIG. 5 are irradiated with light from the substrate side, the BiSI / FTO electrodes (after the HP treatment) are the same as the BiSI / FTO electrodes (before the HP treatment). In comparison, it has been clearly shown that the photoanode current increases (eg, about 3-4 times at 0.3 V vs. Ag / AgCl) and is flattened while promoting the binding between particles by HP treatment. It was found that the intergranular resistance between particles could be effectively reduced.

Further, according to the measurement result of the light irradiation direction dependence of the photoelectrochemical characteristics of FIG. 16, as shown in Table 1 below, the photocurrent density ratio increased about twice before and after the HP treatment, and the HP treatment It was found that the movement characteristics of the photoexcited electrons were improved.

Test Example 2 (Preparation of BiSBr / FTO electrode and evaluation of its characteristics)
In Test Example 1, a BiSBr / FTO electrode (before HP treatment) and a BiSBr / FTO electrode (after HP treatment) were prepared in the same manner as in Test Example 1 except that the BiSI particles were replaced with BiSBr particles.

As a result of XRD measurement of the electrodes before and after the HP treatment, the crystallite diameter of BiSBr was 78 nm, which was the same as that of the particles. Further, it was shown that the diffraction peak ratio of the (110) plane / (121) plane was increased from 0.9 to 1.0 by the HP treatment, and the orientation was ab-axis.

The upper surface SEM image of the BiSBr / FTO electrode (before HP treatment) is shown in FIG. A cross-sectional SEM image of the electrode is shown in FIG.

The upper surface SEM image of the BiSBr / FTO electrode (after HP treatment) is shown in FIG. A cross-sectional SEM image of the electrode is shown in FIG.

In addition, the photoelectrochemical properties of the BiSBr / FTO electrode (before and after HP treatment) were examined in the same manner as in Test Example 1. The measurement result is shown in FIG.

Further, as in Test Example 1, the dependence of the photoelectrochemical properties of the BiSBr / FTO electrode (before and after HP treatment) on the light irradiation direction was investigated. The measurement results are shown in FIG. 17 and Table 2 below.
(Consideration)
As is clear from the results of FIGS. 6 and 8, BiSBr particles are deposited on the FTO electrode while maintaining their particle shape before the HP treatment, but after the HP treatment, one of the deposits (material to be pressed). The portion was flattened, and in the flattened portion, BiSBr particles were bound to each other to the extent that the grain boundaries of the particles could not be seen in the SEM image. In addition, it was confirmed by EDX measurement that the composition of the flattened portion did not change as compared with that before flattening. Further, as is clear from the results of FIGS. 7 and 9, BiSBr particles are coarsely deposited on the FTO substrate before the HP treatment (the film thickness of the deposited layer is 4 to 6 μm), but after the HP treatment, the deposited layer is deposited. Flattened and the film thickness decreased to 2 to 3 μm. From FIG. 9, it was found that the difference in thickness in the width range of 10 μm in the cross section of the pressed molded product in the pressing direction was within 1 μm. In addition, the XRD results showed that the HP treatment resulted in ab-axis orientation, and the Bi-S unit in BiSBr was oriented so that it could be easily bonded to the substrate.

As is clear from the measurement results of the photoelectrochemical properties when the electrodes before and after the HP treatment in FIG. 10 are irradiated with light from the substrate side, the BiSBr / FTO electrodes (after the HP treatment) are the BiSBr / FTO electrodes (before the HP treatment). In comparison, it has been clearly shown that the photoanode current increases (eg, about twice at 0.3 V vs. Ag / AgCl) and can be flattened while promoting the binding between particles by HP treatment. It was found that the intergranular resistance between particles could be effectively reduced.

Further, according to the measurement result of the light irradiation direction dependence of the photoelectrochemical characteristics of FIG. 17, as shown in Table 2 below, the photocurrent density ratio increased about twice before and after the HP treatment, and the HP treatment It was found that the movement characteristics of the photoexcited electrons were improved.

Test Example 3 (Preparation of BiOI / FTO electrode and evaluation of its characteristics)
In Test Example 1, a BiOI / FTO electrode (before HP treatment) and a BiOI / FTO electrode (after HP treatment) were produced in the same manner as in Test Example 1 except that the BiSI particles were replaced with BiOI particles.

As a result of XRD measurement of the electrodes before and after the HP treatment, the crystallite diameter of BiOI was 56 nm, which was the same as that of the particles. Further, it was shown that the diffraction peak ratio of the (001) plane / (200) plane was increased from 11 to 21 by the HP treatment, and the c-axis orientation was obtained.

The upper surface SEM image of the BiOI / FTO electrode (before HP treatment) is shown in FIG. A cross-sectional SEM image of the electrode is shown in FIG.

The upper surface SEM image of the BiOI / FTO electrode (after HP treatment) is shown in FIG. A cross-sectional SEM image of the electrode is shown in FIG.

Moreover, the photoelectrochemical characteristics of the BiOI / FTO electrode (before and after HP treatment) were examined in the same manner as in Test Example 1 (not shown).

Further, as in Test Example 1, the dependence of the photoelectrochemical properties of the BiOI / FTO electrode (before and after HP treatment) on the light irradiation direction was investigated. The measurement results are shown in FIG. 18 and Table 3 below.
(Consideration)
As is clear from the results of FIGS. 11 and 13, the BiOI particles are deposited on the FTO electrode while maintaining their particle shape before the HP treatment, but after the HP treatment, one of the deposits (pressed raw material). The part was flattened, and in the flattened part, the BiOI particles were bound to the extent that the grain boundaries of the particles could not be seen in the SEM image. In addition, it was confirmed by EDX measurement that the composition of the flattened portion did not change as compared with that before flattening. Further, as is clear from the results of FIGS. 12 and 14, the BiOI particles are coarsely deposited on the FTO substrate before the HP treatment (the film thickness of the deposited layer is 4 to 7 μm), but after the HP treatment, the deposited layer is deposited. Flattened and the film thickness decreased to 4 to 5 μm. From FIG. 14, it was found that the difference in thickness in the width range of 10 μm in the cross section of the pressed molded product in the pressing direction was within 1 μm. In addition, the XRD results showed that the HP treatment resulted in a c-axis orientation, and the Bi-O unit in BiSBr was oriented so that it could easily spread horizontally on the substrate.

The photoelectrochemical properties of the BiOI / FTO electrodes (before and after HP treatment) were examined, but no significant difference was observed before and after HP treatment (not shown). However, according to the measurement result of the light irradiation direction dependence of the photoelectrochemical characteristics in FIG. 18, as shown in Table 3 below, the photocurrent density ratio increased about twice before and after the HP treatment, and the HP treatment It was found that the movement characteristics of the photoexcited electrons were improved.

(Comparison and consideration of Test Examples 1 to 3)
Since the decrease in grain boundary resistance in the test examples can be evaluated from the improvement in the photoelectrochemical properties and / or the transfer characteristics of the photoexcited electrons, all of Test Examples 1 to 3 show the effect of reducing the grain boundary resistance. There is. Among them, in BiSI and BiSBr of Test Examples 1 and 2, improvement in photoelectrochemical characteristics and improvement in transfer characteristics of photoexcited electrons were observed, but in BiOI of Test Example 3, only improvement in transfer characteristics of photoexcited electrons was observed. Was noticeably observed.

It is considered that the evaluation of the transfer characteristics of photoexcited electrons in the test example mainly reflects the transfer characteristics of macroscale photoexcited electrons from the vicinity of the substrate to the surface of the material on the opposite bank of the thin film constituting the electrode. Therefore, in Test Examples 1 to 3, it is considered that the movement characteristics of the macroscale photoexcited electrons were improved because the packing of the particles was improved, as observed from SEM and the like, and this was observed.

On the other hand, in the evaluation of photoelectrochemical properties, since light is irradiated from the substrate side, many photons are absorbed near the substrate of each metal composite anion compound, reflecting the relatively microscale physical properties near the substrate. It is possible that it will be done. And, this relatively microscale property may be greatly influenced by the tight binding of the material, the orientation of the material, and the like. In Test Examples 1 and 2, it was found that the materials were tightly bound by the HP treatment, and the electron transfer on the microscale became more advantageous, which improved the photoelectrochemical properties. It can be considered as one of the reasons. From the viewpoint of material orientation, in Test Examples 1 and 2, the ab-axis orientation was obtained by the HP treatment, and the Bi-16 group element anion unit was oriented so as to easily form a bond on the substrate. On the other hand, in Test Example 3, the orientation was c-axis, and the Bi-16 group element anion was easily oriented horizontally on the substrate. Electron transfer within the Bi-16 group elemental anion unit may be more advantageous than electron transfer from the Bi-16 group element anion unit to the halogen anion, and therefore HP treatment is performed. Therefore, it is considered that the improvement of photoelectrochemical properties was observed in Test Examples 1 and 2 in which the orientation was ab-axis. For reference, FIG. 19 shows the crystal structure of BiOX (where X in FIG. 19 indicates a Group 17 elemental anion). Further, at this time, in Test Example 3 having a c-axis orientation, it is advantageous to confine electrons and / holes, and it is suggested that it can be suitably used as a light emitting material.

Test Example 4 (Production of a solar cell using a BiSI pressed molded product as a light absorption layer and evaluation of its characteristics)
An Asahi Glass FTO substrate (25 mm × 25 mm × 2 mm) was prepared.

Then, a suspension in which a 2-propanol solution of 10 mg / ml BiSI particles was suspended by sonication was prepared.

Then, 200 ml of the above suspension was added dropwise to the FTO substrate and dried. This dropping and drying treatment was repeated 3 times. As a result, a BiSI sedimentary layer was formed.

Next, after heating with a hot plate at 50 ° C. for 20 minutes, a quartz plate (25 mm × 25 mm × 2 mm) was placed on the BiSI deposition layer, and the temperature was 120 ° C., atmospheric pressure atmospheric pressure, and pressing with a hot press device (manufactured by SINTO). Press molding was performed under the conditions of a pressure of 5 MPa and a pressing time of 20 minutes. As a result, a light absorption layer (thickness 3 to 4 μm) made of a BiSI pressed molded product was formed on the FTO substrate.

Next, an organic polymer (Spiro-OMeTAD) was formed on the light absorption layer as a hole transport layer (thickness 0.2 μm) by spin coating, and then an Au electrode (thickness 0.) was deposited on the hole transport layer. A solar cell was produced by forming 1 μm).

The solar cell produced was examined for solar conversion efficiency under the conditions shown below.
・ Irradiation light intensity: Solar simulator (100mW / cm ² )
・ Electrode area: 0.12 cm ²
The solar conversion efficiency was about 1 × 10 ^-4 % (J = 0.13mAcm- ² , Voc = 0.002V, FF = 0.25).

Therefore, it can be seen that the pressed molded product in the present embodiment functions as a light absorbing layer of a solar cell material, particularly a solar cell, and can be applied as a solar conversion material.

Test Example 5 (Transfer of BiSI pressed molded product by HP treatment to metal plate)
(Test Example 5-1. Transfer to copper plate)
A BiSI / FTO electrode (before HP treatment) was prepared according to the procedure of Test Example 1.

Next, after sandwiching a copper plate (25 mm × 25 mm × 0.3 mm) on the BiSI / FTO electrode (before HP treatment), a quartz plate (25 mm × 25 mm × 2 mm) is installed and placed in a hot press device (manufactured by SINTO). Press molding (HP treatment) was performed under the conditions of a temperature of 50 ° C., an atmospheric pressure of atmospheric pressure, a pressing pressure of 5 MPa, and a pressing time of 20 minutes.

The copper plate was peeled off after the HP treatment. The left figure of FIG. 20 is a photograph showing the state of the surface of the FTO substrate after the copper plate is peeled off, and the right figure is a photograph showing the state of the back surface of the copper plate after the peeling. From the figure on the right, it can be seen that the dense BiSI pressed molded product is transferred to the back surface of the copper plate.

The top SEM observation image of the transferred BiSI pressed molded product is shown in FIG. From FIG. 21, it can be seen that the surface of the transferred BiSI pressed molded product is almost the same as the form of the FTO substrate (that is, almost no BiSI pressed molded product remains on the FTO substrate). It is presumed that the reason why the dense BiSI pressed molded product was transferred to the back surface of the copper plate in this way is that at least one intermediate layer such as CuI, CuSx, or BiCuxSy was formed between the copper plate and the BiSI pressed molded product. Will be done.
(Test Example 5-2. Transfer to molybdenum plate)
The molybdenum plate was peeled off after press molding (after HP treatment) in the same manner as in Test Example 5-1 except that the copper plate was changed to a molybdenum plate in Test Example 5-1. The left figure of FIG. 22 is a photograph showing the state of the surface of the FTO substrate after the molybdenum plate is peeled off, and the right figure is a photograph showing the state of the back surface of the molybdenum plate after the peeling. From the figure on the right, it can be seen that the dense BiSI pressed molded product is transferred to the back surface of the molybdenum plate.

The top SEM observation image of the transferred BiSI pressed molded product is shown in FIG. From FIG. 23, it can be seen that the surface of the transferred BiSI pressed molded product largely conforms to the form of the FTO substrate (that is, the BiSI pressed molded product hardly remains on the FTO substrate).
(Test Example 5-3. Transfer to CuOx-Cu plate)
The CuOx-Cu plate was peeled off after pressure molding (after HP treatment) in the same manner as in Test Example 5-1 except that the copper plate was changed to a CuOx-Cu plate in Test Example 5-1. The CuOx-Cu plate is obtained by heating the copper plate used in Test Example 5-1 in the air at 300 ° C. for 30 minutes to form an oxide film (CuOx) on the surface of the copper plate.

The top SEM observation image of the transferred BiSI pressed molded product is shown in FIG. From FIG. 24, it can be seen that the surface of the transferred BiSI pressed molded product is almost the same as the form of the FTO substrate (that is, almost no BiSI pressed molded product remains on the FTO substrate).

Incidentally, CuOx was found to be Cu ₂ O by XRD analysis. It was also found that the oxide film (Cu ₂ O) of the Cu ₂ O-Cu plate was maintained before and after the HP treatment. The reason why the dense BiSI pressed molded product was transferred to the back surface of the copper plate in this way is that at least one intermediate layer such as CuI, CuSx, or BiCuxSy was formed between the CuOx-Cu plate and the BiSI pressed molded product. It is speculated.

Claims (33)

The following general formula (1) composed of cation A, anion X and anion Y:
AXY (1)
A pressed molded product containing particles of a metal composite anion compound represented by.
(1) 96 to 100 mol% of the cation A is a Group 15 elemental cation.
(2) The anion X is a group 16 element anion and an anion of an element after the third period of the periodic table , and the amount thereof is 35 to 65 mol% of the total amount of the anion.
(3) The anion Y is a Group 17 elemental anion, and the amount thereof is 35 to 65 mol% of the total amount of the anion.
(4) The crystallite diameter of the particles is 28 nm or more,
(5) in the pressing direction of the cross section of the pressing molding state, and are within 1μm difference in thickness in the range of width 10 [mu] m,
(6) The crystal structure of the metal composite anion compound of the pressed molded product is PDF: 00-043-0652 and / or PDF: 01-075-1811, and in the case of the PDF: 00-043-0652, the above. The orientation ratio (110) / (002) between the (110) crystal plane and the (002) crystal plane of the metal composite anion compound is 2.0 or more, and in the case of the PDF: 01-075-1811, the metal composite The orientation ratio (110) / (121) of the anion compound between the (110) crystal plane and the (121) crystal plane is 1.0 or more.
A pressed molded product characterized by this. The pressed molded product according to claim 1, wherein the amount of the organic molecular cation in the cation A is less than 4 mol%. The pressed molded article according to claim 1 or 2, wherein 98 to 100 mol% of the cation A is a Group 15 elemental cation. The pressed molded article according to any one of claims 1 to 3, wherein the Group 15 elemental cation is a bismuth cation. The pressed molded article according to any one of claims 1 to 4, wherein the amount of the anion X is 40 to 60 mol% of the total amount of the anion. The pressed molded product according to any one of claims 1 to 5 , wherein the group 16 element anion is a sulfur anion. The pressed molded article according to any one of claims 1 to 6 , wherein the amount of the anion Y is 40 to 60 mol% of the total amount of the anion. The pressed molded product according to any one of claims 1 to 7 , wherein the group 17 element anion is an anion of an element from the 4th period of the periodic table. The pressed molded article according to any one of claims 1 to 8 , wherein the group 17 element anion is a bromine anion or an iodine anion. The pressed molded article according to any one of claims 1 to 9 , wherein the metal composite anion compound is BiSBr or BiSI. The pressed molded product according to any one of claims 1 to 10 , wherein the crystal structure of the particles is orthorhombic. The pressed molded article according to any one of claims 1 to 11 , wherein the crystal phase of the particles is a single crystal phase. The pressed molded product according to any one of claims 1 to 12 , which is in the form of a thin film. The pressed molded product according to claim 13 , wherein the thin film has a film thickness of 0.5 to 10.0 μm. The pressed molded product according to any one of claims 1 to 14 , which is an n-type semiconductor. The pressed molded article according to any one of claims 1 to 15 , which is in contact with a conductive material. The pressure-molded article according to claim 16 , wherein the conductive material is a metal. The pressure-molded article according to claim 17 , wherein the conductive material is copper or molybdenum. The pressed molded product according to any one of claims 1 to 15 , which is in contact with a p-type semiconductor. The pressed molded product according to claim 19 , wherein the p-type semiconductor is an inorganic material. The pressed molded product according to claim 19 , wherein the p-type semiconductor is copper halide, copper sulfide, copper oxide or molybdenum oxide. The pressed molded product according to claim 19 , wherein the p-type semiconductor is an organic semiconductor. Use of the pressed molded product according to any one of claims 1 to 22 as a semiconductor material. Use of the pressed molded product according to any one of claims 1 to 22 as a solar cell material. Use of the pressed molded product according to any one of claims 1 to 22 as a light absorption layer of a solar cell. Use of the pressed molded product according to any one of claims 1 to 22 as an optical sensor. Use of the pressed molded product according to any one of claims 1 to 22 as a light emitting material. The following general formula (1) composed of cation A, anion X and anion Y:
AXY (1)
This is a method for producing a pressed molded product by press-molding a pressed raw material containing particles of a metal composite anion compound represented by the above in a state of being sandwiched between inorganic plate materials .
(1) 96 to 100 mol% of the cation A is a Group 15 elemental cation.
(2) The anion X is a group 16 element anion and an anion of an element after the third period of the periodic table , and the amount thereof is 35 to 65 mol% of the total amount of the anion.
(3) The anion Y is a Group 17 elemental anion, and the amount thereof is 35 to 65 mol% of the total amount of the anion.
(4) The metal by performing the press molding by applying a pressing pressure of 0.1 MPa to 20 MPa for 1 second to 20 hours in an atmospheric pressure of 0.01 Pa to 2 MPa under a temperature condition of 0 to 300 ° C. The crystal structure of the composite anion compound is PDF: 00-043-0652 and / or PDF: 01-075-1811, and in the case of the PDF: 00-043-0652, the (110) crystal plane of the metal composite anion compound. And (002) crystal plane orientation ratio (110) / (002) is 2.0 or more, and in the case of the PDF: 01-075-1811, the (110) crystal plane and (110) crystal plane of the metal composite anion compound 121) Obtain the pressed molded product having an orientation ratio (110) / (121) with respect to the crystal plane of 1.0 or more.
A method for producing a pressed molded product. The manufacturing method according to claim 28 , which is the method for manufacturing a pressed molded product according to any one of claims 1 to 22 . The production method according to claim 28 or 29 , wherein the temperature condition is 20 to 200 ° C. The production method according to any one of claims 28 to 30 , wherein the pressing pressure is 0.6 MPa to 10 MPa. The manufacturing method according to any one of claims 28 to 31 , wherein the time for applying the pressing pressure is 10 seconds to 10 hours. The production method according to any one of claims 28 to 32 , wherein the pressure molding is performed so as to form a thin film.