JP6487409B2 - Compound - Google Patents

Description

  The present invention relates to compounds, processes for their preparation and their use.

In recent years, organic inorganic metal halides have attracted attention in various applications such as solar cell applications. In Non-Patent Document 1, the composition ratio is CH (NH ₂ ), which is composed of formamidinium cation (CH (NH ₂ ) ₂ ⁺ ), lead cation (Pb ²⁺ ) and iodine anion (I ⁻ ) as organic ammonium. (CH (NH ₂ ) ₂ ) PbI _{3 where 2} : Pb: I = 1: 1: 3 has a large yellow band gap (CH (NH ₂ ) ₂ ) PbI when manufactured at a heating temperature of about 100 ° C. It is described that it becomes ₃ compounds.

In Non-Patent Document 2, the (CH (NH ₂ ) ₂ ) PbI ₃ compound is heated at 170 ° C. or more to give a black (CH (NH ₂ ) ₂ ) PbI ₃ compound having an absorption edge of about 820 nm. It is described. Incidentally, formamidinium cation, what is known as a lead cations and halogen anions only compound composed of are disclosed in Non-Patent Document 1 and Non-Patent Document _{2, (CH (NH 2)} 2) PbI ₃ only.

  On the other hand, organic lead halides are known to have a layered structure by containing a bulky ammonium cation having a carbon number of greater than 3 and non-patent document 3 discloses normal butyl ammonium cation (: BA , Carbon number 4), methyl ammonium cation (: MA), lead cation, iodine anion, BA: MA: Pb: I = 2: 1: 2: 7, 2: 2: 3: 10, 2: It is disclosed that a compound of a four-component system (three cations, one anion) having a ratio of 3: 4: 13 can be produced at a heating temperature of about 100.degree. Further, Non-Patent Document 3 describes that having a layered structure has an advantage that it can be made with a compound such as a flat thin film having a high coverage even with a relatively simple manufacturing method.

J. Phys. Chem. Lett. 2015, 6, 1249. J. Phys. Chem. C 2014, 118, 16458. J. Am. Chem. Soc. 2015, 137, 7843.

  However, the compound described in Non-Patent Document 1 is desired to have a short wavelength at the absorption edge and a smaller band gap. For example, in order to use longer wavelength light, which is often contained in sunlight, and improve light absorption characteristics, development of a material having a smaller band gap is required.

  The compound described in Non-patent Document 2 generates photoexcited carriers when used at room temperature, for example, when a voltage is applied, for a material that is a high temperature stable phase that requires high temperature to produce At the time, etc., there may occur a change in the compound accompanied by a change in physical properties such as a phase transition. From the viewpoint of operational stability, development of a compound that can be produced at lower temperatures is required.

  It is desirable that the compound has a layered structure in order to not only have the above-mentioned superiority but also have excellent uniformity of performance. However, in the techniques described in Non-Patent Document 1 and Non-Patent Document 2, there is a problem that the organic ammonium cation is only formamidium cation, that is, the layer structure can not be formed due to the ionic radius being too small. is there. Although the compound described in Non-Patent Document 3 has a layered structure, it becomes easier to manufacture, and distribution of the composition is less likely to occur when the area is enlarged, and in order to be more excellent in uniformity of performance, the compound It is desirable that the number of types of cations and anions that make up the majority be smaller. In particular, in view of the large ion radius and difficulty in diffusion, it is desirable that the total of two cations constituting the compound is less than the compound described in Non-Patent Document 3 in most of the cations constituting the compound.

  The present invention has been made in view of the problems of the above-mentioned prior art, and provides a compound excellent in uniformity of performance, excellent in light absorption characteristics, and excellent in operation stability, a method of manufacturing the same, and a method of use thereof The purpose is to

  As a result of intensive research and experiments to solve the problems of the prior art, the present inventors have found that the problems can be solved by using a predetermined cation and a predetermined anion as a compound having a predetermined composition. The present invention has been completed.

That is, the present invention is as follows.
[1]
A compound containing a cation and an anion,
10 mol% or more and 49 mol% or less of the cations are Group 14 element cations,
51 mol% or more and 90 mol% or less of the cation is a counter cation, wherein 91 mol% or more and 100 mol% or less of the counter cation is a single kind having 1 or more and 2 or less carbon atoms and nitrogen An organic molecular cation having a number of 2 or more and 4 or less,
30 mol% or more and 100 mol% or less of the anions are Group 17 element anions,
The compound, wherein the maximum interplanar spacing in the crystal structure of the compound is 8 Å or more and 30 Å or less.
[2]
The compound according to [1], wherein 95 mole% or more and 100 mole% or less of the counter cation is the organic molecule cation.
[3]
The compound according to [1] or [2], wherein the nitrogen number of the organic molecule cation is 2 or more and 3 or less.
[4]
The compound in any one of [1]-[3] whose carbon number of the said organic molecule cation is one.
[5]
The compound in any one of [1]-[4] in which the said organic molecule cation contains an ammonium group and / or an amine group.
[6]
The compound in any one of [1]-[5] that the said organic molecular cation contains a formamidium cation.
[7]
The compound in any one of [1]-[6] which is 55 to 85 mol% of counter cations among the said cations.
[8]
The compound in any one of [1]-[7] whose 15 mol% or more and 45 mol% or less are group 14 element cations among the said cations.
[9]
The compound in any one of [1]-[8] whose said group 14 element cation is a tin cation and / or a lead cation.
[10]
The compound in any one of [1]-[9] whose 55 mol% or more and 100 mol% or less are group 17 element anions among the said anions.
[11]
The compound according to any one of [1] to [10], wherein the anion of the Group 17 element is at least one selected from the group consisting of a chloride anion, a bromide anion and an iodide anion.
[12]
The compound is a compound represented by (CH (NH ₂ ) ₂ ) ₂ PbX ₄ (wherein X is at least one selected from the group consisting of Cl, Br or I), [1] -The compound as described in any one of-[11].
[13]
The compound is a compound represented by (CH (NH ₂ ) ₂ ) ₃ PbX ₅ (wherein X is at least one selected from the group consisting of Cl, Br or I), [1] -The compound as described in any one of-[11].
[14]
The compound in any one of [1]-[13] whose crystal structure of the said compound is a perovskite structure.
[15]
The compound in any one of [1]-[14] whose form is particle | grains.
[16]
The compound in any one of [1]-[14] whose form is a thin film.
[17]
It is a composition used as a precursor of the compound in any one of [1]-[16],
An aprotic polar organic solvent, the group 14 element cation, the organic molecule cation, and the group 17 element anion,
The content of the Group 14 element cation in the composition is 0.05 mol / L or more and 3.0 mol / L or less, and the content of the organic molecular cation is 0.05 mol / L or more. The composition, which is 0 mol / L or less and the content of the group 17 element anion is 0.05 mol / L or more and 10.0 mol / L or less.
[18]
The composition according to [17], wherein the ratio of the organic molecular cation to the group 14 element cation (organic molecule cation / group 14 element cation) contained in the composition is 1.1 or more and 4 or less.
[19]
A method for producing a compound according to any one of [1] to [16], wherein
The manufacturing method of a compound including the process of heating the composition as described in [17] or [18] at the temperature of 0 degreeC or more and 160 degrees C or less.
[20]
Use of the compound according to any one of [1] to [16] as a semiconductor material.
[21]
Use of the compound according to any one of [1] to [16] as a solar cell material.
[22]
Use of the compound according to any one of [1] to [16] as a light absorbing layer of a solar cell.
[23]
Use of the compound according to any one of [1] to [16] as a light sensor.
[24]
Use of the compound according to any one of [1] to [16] as a light emitting material.
[25]
(CH (NH ₂ ) ₂ ) PbX ₃ (wherein X is at least one selected from the group consisting of Cl, Br and I), which has a perovskite structure, of the compound according to any one of [1] to [16] Use as a precursor of

  The compound according to the present invention is excellent in the uniformity of the performance, the light absorption property and the operation stability.

  Hereinafter, modes for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The following present embodiment is an example for describing the present invention, and is not intended to limit the present invention to the following contents. The present invention can be implemented with various modifications within the scope of the gist.

(Compound)
The compound of the present embodiment is a compound containing a cation and an anion, and 10 mol% or more and 49 mol% or less of the cation is a 14th element cation, and 51 mol% or more and 90 mol% or less of the cation Is a counter cation, wherein 91 mol% or more and 100 mol% or less of the counter cations are a single kind of organic molecular cation having 1 or more and 2 or less and 2 or more and 4 or less nitrogen numbers. 30 mol% or more and 100 mol% or less of the anions are Group 17 element anions, and the maximum interplanar spacing in the crystal structure of the compound is 8 Å or more and 30 Å or less. Since it is comprised in this way, the compound of this embodiment is excellent in the uniformity of performance, excellent in a light absorption characteristic, and excellent in operation stability.
In the present specification, “excellent in uniformity of performance” means a layered structure, and the main counter cation constituting the compound is a single kind having 1 to 2 carbon atoms and nitrogen It means that the number is limited to an organic molecular cation having 2 or more and 4 or less.
The phrase “having a layered structure” means that the maximum interplanar spacing is 8 Å or more and 30 Å or less, and the “limited to a single type of main counter cation” means that the organic molecular cation is a pair. It means that it is 91 mol% or more of the cations, that is, all the counter cations excluding the impurities are the organic molecule cations and the like.
The term "excellent in light absorption characteristics" means that the absorption edge of the material is 460 nm or more and 1000 nm or less.
Further, “excellent in operation stability” means that it can be prepared at 0 ° C. or more and 160 ° C. or less.

  As described above, in the compound of the present embodiment, 10 mol% or more and 49 mol% or less of the cations are group 14 element cations. Such a configuration is important from the viewpoint of forming a layered structure, the viewpoint of improving the light absorption characteristics, and the viewpoint of improving the operation stability. From the viewpoint of being advantageous for light absorption characteristics and being advantageous for crystallization of the compound, the content of the group 14 element cation is preferably 15 mol% or more, more preferably 20 mol%, and still more preferably 25 mol%. Moreover, from a viewpoint that many counter cations can be contained, 45 mol% or less is preferable and, as for content of a 14th group element cation, 40% or less is more preferable.

Examples of the group 14 element cation include, but are not limited to, Si ⁴⁺ , Ge ²⁺ , Ge ⁴⁺ , Sn ²⁺ , Sn ⁴⁺ , and Pb ²⁺ . From the viewpoint of being advantageous to the formation of the octahedral structure with the anion of the Group 17 element, and from the viewpoint of widening the density of states of each of the Group 14 element cation and the anion by increasing the covalent bondability Therefore, divalent cations are preferable, and specifically, Ge ²⁺ , Sn ²⁺ , Pb ^{2+ and the} like are preferable. In addition, from the viewpoint of being relatively stable to oxidation, Sn ²⁺ and Pb ²⁺ are more preferable, and Pb ²⁺ is more preferable. As described above, in the present embodiment, it is particularly preferable that the Group 14 element cation contains at least one of a tin cation and a lead cation.

  The compound in the present embodiment is a cation other than the group 14 element cation and the element cation of three or more cycles among the contained cations (also referred to as “counter cation” in the present specification). Is included. Such a configuration is important from the viewpoint of forming a layered structure, the viewpoint of improving the light absorption characteristics, and the viewpoint of improving the operation stability. From the viewpoint of being advantageous to the arrangement of the Group 14 element cation, 55 mol% or more is preferable, and 60 mol% or more is more preferable. Further, from the viewpoint of being able to contain a large amount of the Group 14 element cation, 85 mol% or less is preferable, 80 mol% or less is more preferable, and 75 mol% or less is more preferable.

  In the present embodiment, 91 mol% to 100 mol% of the counter cation is a single kind of organic molecular cation having 1 to 2 carbon atoms and 2 to 4 nitrogen atoms. By being configured in this manner, the compound is excellent in the uniformity of the performance. In particular, increasing the proportion of organic cations having a relatively low carbon number and a high nitrogen number is advantageous for the formation of conjugation, thus strengthening the bond that forms the organic molecular cation, and the cation of the positively charged site It is advantageous to strengthen the sex and to be advantageous to the organic molecular cation itself and the thermal stability of the compound. From the viewpoint of excellent uniformity of performance, the organic cation is preferably 95 mol% or more and 100 mol% or less, more preferably 98 mol% or more and 100 mol% or less, and more preferably 99 mol% or more and 100 mol% or less. The following are more preferable. On the other hand, from the viewpoint of easy purification of the raw material, the content of the organic molecule cation is preferably 99.999 mol% or less, more preferably 99.99 mol% or less, and still more preferably 99.9 mol% or less. The number of carbon atoms constituting the organic molecule cation is preferably 1 from the viewpoint of strengthening the bond forming the organic molecule cation and the cation enhancement of the positively charged site. In addition, the number of nitrogen contained in the counter cation is preferably 2 or more and 3 or less, and most preferably 2 from the viewpoint of being advantageous for the formation of the crystal structure of the compound. The organic molecule cation preferably has an ammonium group and / or an amine group from the viewpoint of being advantageous for the formation of the compound. Specific examples of the organic molecular cation include, but are not limited to, formamidinium cation, acetamidinium cation, guanidinium cation, and isomers thereof, and the like, for forming a crystal structure of the compound. From the viewpoint of being advantageous, formamidinium cations and guanidinium cations are preferred, and formamidinium cations are most preferred.

  In the present embodiment, inorganic cations can be included in the counter cations of the compound. The inorganic cations include metal cluster cations and single element cations, and are preferably single element cations from the viewpoint of easy production. For example, the single-element cation contained in the counter cation can contain 1 mol% or more of the counter cations constituting the compound from the viewpoint of being advantageous to heat resistance and from the viewpoint of being able to relieve distortion of the perovskite structure. . From the viewpoint of being advantageous to the formation of the perovskite structure, any element selected from the group consisting of Group 1 elements, Group 2 elements, and Group 3 elements is preferable, and is selected from the group consisting of Group 1 elements Is more preferable. Specifically, lithium, potassium, sodium, rubidium, cesium, magnesium, calcium, strontium, barium, scandium, lanthanum, cerium, scandium and the like can be mentioned, and lithium, potassium, sodium from the viewpoint of formation of the perovskite structure Rubidium, cesium and the like are preferable, rubidium and cesium are more preferable, and cesium is most preferable.

  The number of types of cation of the compound is preferably small from the viewpoint of excellent uniformity of performance. For example, it is most preferable that the compound is constituted of only two kinds of the group 14 cation of one kind of all cations and one kind of counter cation in total.

It is preferable that the anion which comprises a compound contains 30 mol% or more and 100 mol% or less of the anion of a group 17 element with respect to the total amount of the anion contained from a viewpoint which is advantageous to crystallinity improvement. From the viewpoint of being advantageous to the improvement of crystallinity, it is more preferable to contain 55 mol% or more and 100 mol% or less, further preferably 70 mol% or more and 100 mol% or less, and contained 80 mol% or more and 100 mol% or less More preferable. Specific Group 17 elements are not particularly limited, and include, for example, iodine, bromine, chlorine, fluorine and the like, and iodine, bromine and chlorine are preferable from the viewpoint of being advantageous in reducing the band gap, More preferred are iodine and bromine, and more preferred is iodine. Further, it may contain a molecular anion, and a specific molecular anion is not particularly limited, and examples thereof include a molecular anion containing carbon and nitrogen, an inorganic molecular anion, and the like. Specifically, cyanide anion, cyanate anion, thiocyanate anion, selenocyanate anion, BF ₄ ^- anion, PF ₆ ^- anion, CF ₃ COO ^- anion and the like can be mentioned.

The maximum interplanar spacing in the crystal structure of the compound of this embodiment is 8 Å or more and 30 Å or less. With such a crystal structure, the uniformity of the performance is excellent. From the viewpoint of being more excellent in uniformity of performance, the maximum interplanar spacing in the crystal structure of the compound is preferably 10 Å or more, and more preferably 12 Å or more. Further, from the viewpoint of making the absorption edge a long wavelength and reducing the band gap, 20 Å or less is preferable, and 15 Å or less is more preferable. The maximum interplanar spacing in the crystal structure of the compound can be measured by the method described in the examples described later. In addition, for example, the maximum interplanar spacing in the crystal structure of the compound can be adjusted to the above range by adopting a method for producing a preferable compound described later.
The compound is advantageous in diffusion of carriers such as electrons and holes, and advantageous in reducing the band gap, and for prolonging the life of excited carriers (electrons, holes and the like) by light and the like. From the viewpoint of being advantageous, it is preferable to have a perovskite structure. The compound having a perovskite structure is composed of cations of A site and B site and an anion of X site. Examples of such compounds may be general formula include A ₂ BX _4, in this example, for example the cation of the A site is ^{_{CH (NH 2) 2 +,}} B site cations in Pb ²⁺ , the anion of X site I ^- to correspond as respectively. The cation at the B site is six-coordinated to the anion at the X site to form a symmetric or asymmetric octahedron, and this octahedron structure is vertex-shared with a planar structure or a three-dimensional structure. There is.
The crystal structure or crystallite diameter can be evaluated by X-ray crystal structure analysis or a lattice image of a transmission electron microscope image. Specifically, it can be evaluated based on the method described in the examples described later. In addition, the above-mentioned crystal structure can be obtained, for example, according to the method for producing a preferable compound described later. As a method of evaluating whether it is a perovskite structure, for example, a diffraction peak of 2θ = 14 to 15 °, which is a diffraction angle of an XRD derived from the spacing shared by the apex of the octahedral structure by Pb ²⁺ cation and I ⁻ cation, etc. It can be determined from

  The band gap of the compound is preferably small from the viewpoint of being able to use visible light of a long wavelength, which is often contained in sunlight and the like. In particular, the use of long wavelength light is important for the use of sunlight. Specifically, 2.6 eV or less is preferable, 2.5 eV or less is more preferable, and 2.4 eV or less is more preferable. On the other hand, from the viewpoint of reducing the electromotive force of photoexcited carriers, the band gap is preferably 1.0 eV or more, more preferably 1.2 eV or more, and still more preferably 1.4 eV or more.

  The absorption edge of the compound is preferably a long wavelength from the viewpoint of being able to use visible light of a long wavelength contained in a large amount of sunlight or the like. In particular, the use of long wavelength light is important for the use of sunlight. Specifically, 460 nm or more is preferable, 480 nm or more is more preferable, 500 nm or more is more preferable, and 530 nm or more is most preferable.

  The compound of the present embodiment can take various forms, but is preferably in the form of particles or a thin film from the viewpoint of easy handling and the viewpoint of being advantageous to the laminated structure.

(Method for producing compound)
Although it does not specifically limit as a manufacturing method of the compound of this embodiment, For example, it can pass through a predetermined | prescribed process using the predetermined | prescribed raw material mentioned later. The raw material of the compound of the present embodiment is not particularly limited as long as it is a substance containing an element constituting the compound, and various substances can be used as the raw material. In particular, from the viewpoint of being able to obtain a compound in the low temperature phase and obtaining a compound excellent in operation stability, it is a composition to be a precursor of the compound of the present embodiment, and is a composition having a predetermined concentration and molar ratio It is preferable to include the step of preparing a composition containing the anion, and it is more preferable to include the step of heating the composition at a relatively low temperature. More specifically, the composition comprises an aprotic polar organic solvent, the group 14 element cation, the organic molecule cation, and the group 17 element anion, in the composition The content of the cation of the Group 14 element is 0.05 mol / L or more and 3.0 mol / L or less, and the content of the organic molecular cation is 0.05 mol / L or more and 3.0 mol / L or less The content of the Group 17 element anion is preferably 0.05 mol / L or more and 10.0 mol / L or less. Further, the ratio of the organic molecular cation to the Group 14 element cation (organic molecular cation / Group 14 element cation) contained in the composition is more preferably 1.1 or more and 4 or less.
Moreover, it is more preferable that the manufacturing method of the compound of this embodiment includes the process of heating the above-mentioned composition at 0 degreeC or more and 160 degrees C or less. In order to include a layered structure of 8 Å to 30 Å in the crystal structure of the compound, it is important that the precursor contains the cation and the anion at a predetermined concentration and molar ratio. According to the said predetermined precursor, it can manufacture by including the process of heating this compound at 0 degreeC or more and 160 degrees C or less. That is, the operation stability is excellent.

  In addition to the above, metal halides can be used as raw materials for producing the compound of the present embodiment. Specific examples of the metal halide include, but are not limited to, lead chloride, lead bromide, lead iodide and the like, which are advantageous for the formation of the obtained compound of the present embodiment, and the band gap is reduced. From the viewpoint of being advantageous, lead bromide and lead iodide are preferred, and lead iodide is more preferred.

A salt preferably used as a raw material of the compound of the present embodiment can be obtained from a predetermined acid and a base, and the acid is a hydrogen halide or the like, and the base has 1 or more and 2 or less and 2 or more nitrogen atoms. The salt etc. which are components derived from the organic amine which is four or less are mentioned.
In addition, as the component derived from the organic amine, the formation of the crystal structure of the compound of the present embodiment to be obtained becomes easy, and the carbon number of the organic amine is 1 from the viewpoint of excellent uniformity of performance. The nitrogen number of the organic amine is more preferably 2 or more and 3 or less, and most preferably 2 or more.

  Specific examples of salts of the above bases and hydrogen halides include, but are not limited to, formamidine hydrogen chloride, formamidine hydrogen iodide, formamidine hydrobromide, acetamidine hydrogen chloride And acetamidine hydroiodide, acetamidine hydrobromide, guanidine hydrochloride, guanidine hydroiodide, guanidine hydrobromide, and the like, which facilitates the formation of the compound. From the viewpoint, formamidine hydrochloride, formamidine hydroiodide, formamidine hydrobromide are preferable.

  The compound of the present embodiment can also be produced by a method using no solvent or a method using a solvent. As a method which does not use a solvent, although not limited to the following, for example, a vapor deposition method, a solid phase method and the like can be mentioned. From the viewpoint of producing a compound having a uniform composition, the compound of the present embodiment is produced by a method using a solvent, that is, a method of crystallization by removing the solvent from a solution in which the raw material is dissolved in the solvent. Is preferred. That is, the method for producing a compound according to this embodiment comprises the steps of: dissolving a substance containing the predetermined cation and anion described above in an aprotic organic solvent to obtain a solution; and removing the solvent from the solution Preferably,. In the above, from the viewpoint of being advantageous for the dissolution of the Group 14 element halide, which is a preferable raw material of the compound of the present embodiment, an aprotic organic solvent is used as the solvent. Specifically, dimethylformamide (hereinafter referred to as DMF), dimethylsulfoxide (hereinafter referred to as DMSO), γ-butyrolactone and the like are preferable, and from the viewpoint of excellent dissolution of the Group 14 element halide, DMF and DMSO are preferable. More preferable.

  It is preferable to include the process of preparing the composition used as the precursor of this compound using the said raw material. Specifically, the composition includes an aprotic polar organic solvent, the group 14 element cation, the organic molecule cation, and the group 17 element anion, and the composition in the composition The content of the cation of the Group 14 element is 0.05 mol / L or more and 3.0 mol / L or less, and the content of the organic molecular cation is 0.05 mol / L or more and 3.0 mol / L or less And the content of the Group 17 element anion is 0.05 mol / L or more and 10.0 mol / L or less. Since the composition is excellent in the solubility of the raw material in the solvent by satisfying the above conditions, it is possible to alleviate the necessity of controlling the production conditions and to improve the uniformity of the compound to be produced. From the viewpoint of excellent uniformity of the performance of the compound, excellent light absorption characteristics, and excellent operation stability, the cation of Group 14 element contained in the composition is 0.2 mol / L or more and 2.0 mol / L or more. The following is more preferable, 0.5 mol / L or more and 1.5 mol / L or less is more preferable, and the organic molecular cation is 0.2 mol / L or more and 2.0 mol / L or less is more preferable 0.5 More preferably, mol / L to 1.5 mol / L, more preferably 0.5 mol / L to 7.0 mol / L of the group 17 element anion, and 1.0 mol / L to 4.0. Mole / L or less is more preferable. Further, from the viewpoint of excellent solubility of the raw material and the viewpoint of being advantageous for the formation of the compound, the aprotic organic solvent is preferably γ-butyrolactone, DMF, DMSO or the like.

  The ratio of organic molecular cation to Group 14 element cation contained in the composition (organic molecule cation / group 14 element cation) from the viewpoint of excellent uniformity of performance, excellent light absorption characteristics, and excellent operation stability. Is more preferably 1.2 or more and 4 or less, and still more preferably 1.3 or more and 3 or less.

  Particularly preferred is a method of producing a compound by further carrying out the step of removing the solvent from the solution prepared as described above. The step of removing the solvent from the solution is not particularly limited, but examples thereof include a step of evaporating and removing the solvent by heating, and a step of removing the solvent which is a good solvent by contacting or mixing with a poor solvent.

  It is preferable that the heating temperature of the said precursor is 0 degreeC or more and 160 degrees C or less from a viewpoint which is excellent in operation | movement stability. From the viewpoint of being advantageous to the reaction rate, the heating temperature is more preferably 20 ° C. or more, and still more preferably 40 ° C. or more. From the viewpoint of excellent operation stability, 140 ° C. or less is more preferable, and 120 ° C. or less is more preferable.

  Immobilization of raw materials for producing the compound, for example, a method of producing the compound in the form of a thin film is not limited to the following, but may be a spin coating method, a spray method, a liquid phase reaction method or the like using a solution. The spin coating method is preferred from the viewpoint of reducing the risk of solution ignition and / or easy preparation of the preparation method. In addition, from the viewpoint of removing excess solvent and promoting nucleation, it is preferable to form crystals using a poor solvent. Poor solvents include dimethyl ether, diethyl ether, chlorobenzene, toluene and the like.

  The atmosphere for producing the compound is not particularly limited. For example, although the atmosphere can be prepared in the air or in an inert atmosphere, it is preferable to prepare in the air from the viewpoint of easier preparation.

(Use)
The compound of the present embodiment can be used as a semiconductor material. Examples of the semiconductor material in the present embodiment include materials having an energy difference between the upper end of the valence band and the lower end of the conduction band.

  The compounds can also be used for other applications. Specifically, materials that conduct electrons or holes or ions, materials that use the generation of photoexcited carriers by light absorption, materials that use light emission due to their recombination, etc. They are for battery materials, for light absorbing layers of solar cells, for light sensors, for photocatalysts, light emitting materials, ion conductive materials, conductive materials, piezoelectric elements, power devices and the like. The ion in this embodiment refers to the cation or anion which comprises this material. It is preferable that it is a compound for light absorption layers of a solar cell from a viewpoint which can absorb the light of the wavelength contained in sunlight. In addition, since the binding energy of excitons is increased by the layered structure, it is preferable to use as a light emitting material from the viewpoint of being advantageous for light emission. Furthermore, from the viewpoint of being able to use light of a specific wavelength, it is preferable to use it as an optical sensor.

  Since the compound of the present embodiment has excellent light absorption properties, it is preferably applied to a solar battery cell containing the compound, a solar cell containing the compound in the special light absorption layer, and further, photocurrent density, open Voltage and / or fill factor can be improved. Furthermore, it is possible to improve the solar light conversion efficiency in combination with the light absorption characteristics of the compound and the improvement of each parameter as the solar battery cell.

The compound of the present embodiment can also be a precursor of (CH (NH ₂ ) ₂ ) PbI ₃ having a perovskite structure. For example, by heating the compound of the present embodiment at 165 ° C. or more and 250 ° C. or less and 1 minute or more and 5 hours or less, (CH (NH ₂ ) ₂ ) PbI ₃ having a perovskite structure with few impurities such as PbI ₂ is produced. can do. The heating temperature is preferably 175 ° C. or more, more preferably 185 ° C. or more, from the viewpoint of improving the reaction rate of phase transition, and preferably 220 ° C. or less from the viewpoint of controlling excessive decomposition of components constituting the compound. 200 degrees C or less is more preferable. The heating time is preferably 5 minutes or more, more preferably 10 minutes or more, from the viewpoint of sufficiently advancing the phase transition, and preferably 2 hours or less from the viewpoint of controlling excessive decomposition of the components constituting the compound. 1 hour or less is more preferable.

(Constitution)
It is preferable that the compound of the present embodiment is in contact with the electron transporting material from the viewpoint of being excellent in carrier transfer anisotropy. 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 advantageous for the transport of electrons. When the compound is a thin film, it is preferable that the electron transporting material in contact is also a thin film, from the viewpoint of increasing the contact area to be advantageous for the movement of electrons. The electron transporting material includes an embodiment containing an organic substance or an inorganic substance, but the electron transporting material preferably contains an inorganic substance from the viewpoint that the strength combined with the compound is high because the strength is high; From the viewpoint of relative ease, metal compounds are more preferable. It is more preferable that the electron transporting material is a metal oxide from the viewpoint of being relatively easy to manufacture and store in the atmosphere. 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 and the like, and from the viewpoint of a small effective mass of electrons Titanium oxide and niobium oxide are preferable, and titanium oxide is particularly preferable from the viewpoint of being abundant in materials and inexpensive. From the viewpoint of reducing defects such as pinholes of the electron transporting material, it is preferable to subject the electron transporting material to a process of adsorbing and reacting a precursor material. Specifically, it is preferable to apply a treatment (hereinafter referred to as a TiCl ₄ treatment) to adsorb titanium chloride species onto an electron transport material and then hydrolyze it to bind titanium oxide.

  The compound of the present embodiment is preferably in contact with the hole transport material from the viewpoint of being able to have carrier transfer anisotropy. The hole transport material referred to here is a semiconductor or the like in which the effective mass of the hole is smaller than that of the electron, and is a material or the like advantageous for the transport of the hole. When the compound is a thin film, it is preferable that the hole transporting material in contact is also a thin film, from the viewpoint of increasing the contact area to be advantageous for the movement of electrons. The hole transport material may include an organic substance or an inorganic substance, but the hole transport material preferably contains an organic substance from the viewpoint of making it difficult to form a film defect due to bending when the material is soft. Specific examples include aggregates of organic molecules and organic polymers. More specifically, Spiro-OMeTAD, poly (3-hexylthiophene-2,5-diyl) (: P3HT), poly [bis (4-phenyl) (2,4,6-trimethylphenyl) amine] (: PTAA), N, N-bis (3-methylphenyl) -N, N-diphenylbenzidine (: TPD), N, N-di [(1-naphthyl) -N, N-diphenyl] -1,1-biphenyl ) -4,4-diamine (: NPD), tris (4-carbazoyl-9-ylphenyl) amine (: TCTA), poly (9-vinylcarbazole) (: PVK), 4,4-bis (N-carbazolyl) And the like, and it is advantageous to form an ohmic contact with a p-type material, since the HOMO level is relatively deep. The carrier density can be increased, it can be advantageous for hole transport and, from the viewpoint of increasing the electromotive force, Spiro-OMeTAD are preferred. Spiro-OMeTAD is preferably doped with LiTFSI or an oxidizing agent, for example, from the viewpoint of excellent conductivity.

  Hereinafter, the present embodiment will be more specifically described by citing specific examples and comparative examples, but the present embodiment is not limited at all by these examples and comparative examples as long as the gist thereof is not exceeded. Absent. Physical properties, reaction conditions, and identification of products in Examples and Comparative Examples described later were measured and set by the methods described below.

(Cation content and anion content)
The amount of the group 14 cation, the amount of the counter cation and the amount of the halogen anion contained in the compound are evaluated by SEM-EDX (SEM: SU-70, manufactured by Hitachi, EDX: EMAX X-max, manufactured by Horiba, Ltd.) for the sample. It asked by doing.

(Crystal structure)
The crystal structures of thin film and powder samples were evaluated from X-ray diffraction (XRD) patterns measured using an X-ray diffractometer (D8, manufactured by Bruker). In particular, it has a perovskite structure, I ^- octahedra 2 [Theta] = 14 to 15 ° attributed to diffraction peaks derived from corner-sharing structure according Pb ²⁺ of 6-coordinated to (d = 6 .3 to 5.9 Å) were evaluated. The maximum d value in the crystal structure (the maximum interplanar spacing in the crystal structure of the compound) was calculated from the d value of the diffraction peak of the lowest angle in the XRD pattern.

(Band gap)
The absorbance measured as described below for the thin film prepared in each example is taken as the ordinate, and the intersection of the tangent of the attenuation curve and the baseline of the graph with the wavelength taken as the abscissa is taken as the absorption edge of this material The band gap energy was calculated from the following equation from the wavelength of the end.
(Band gap energy) = 1240 / (wavelength of absorption edge)
The absorbance of the thin film was measured using a spectrophotometer U4100 (manufactured by Hitachi, Ltd.) at a scanning speed of 300 nm / min.

(Solar cell characteristics evaluation)
The solar cell characteristic evaluation of the produced cell was evaluated by the following apparatus and evaluation method.

[apparatus]
(Simulated sunlight)
The pseudo-sunlight was used by adjusting the irradiation amount to 100 mW / cm.sup.- ² with a photodiode using a solar simulator (MP-160, manufactured by Eko Seiki Co., Ltd.). The irradiation area to the irradiation cell was 0.02 cm ⁻² in any cell.
(DC power supply)
The voltage application to the cell, the evaluation of the photocurrent value, and the sweep operation of the applied voltage were performed using a source meter (6242, manufactured by ADCMT).

[Evaluation method]
(Short circuit current density)
The short-circuit current does not apply a voltage to the manufactured cell, but the photocurrent density which flows when the pseudo-sunlight is irradiated, in one sheet, in the three independent electrode structures manufactured later, Calculated from the average value.

(Open voltage)
The open circuit voltage is the average value of the voltage applied to the cell at which the current value becomes 0 when irradiated with the pseudo-sunlight in the three independent electrode structures manufactured later in one sheet. Calculated.

(Fill factor)
The fill factor (hereinafter also referred to as “F. F.”) shorts the value (maximum actual power) at which the power is maximized when the applied voltage is swept while irradiating the pseudo-sunlight. It calculated | required from the following formula which divided by the value which integrated current density and open circuit voltage.
(F.F.) = (Real power maximum value) / ((short circuit current density) × (open circuit voltage))
With respect to this value, the average value of three independent electrode structures manufactured later in one sheet was taken as the fill factor in the example.

(Solar energy conversion efficiency)
The solar energy conversion efficiency (hereinafter also referred to as conversion efficiency) was determined from the following equation.
(Conversion efficiency) = (actual power maximum value (mW cm ^-2 )) / 100mW cm ^-2
About this value, the value of the average in three independent electrode structures produced later among 1 sheet was made into the conversion efficiency in the Example.

(Light sensor function)
The photo sensor function is that when the produced cell is irradiated with pseudo-sunlight (100 mW / cm ^-2 ), a photovoltaic power is generated and the photovoltaic power When it did not generate | occur | produce, it evaluated as "x" as what does not have an optical sensor function, respectively.

(impurities)
In the XRD pattern of the sample prepared in the example, when a diffraction peak derived from a compound other than the perovskite structure having an intensity of 20% or more exists with respect to the intensity of the diffraction peak at 2θ = 14 to 15 ° derived from the perovskite The samples were evaluated as “×” because the amount of impurities was large, and as “○” when they were not present, as the amount of impurities was small.

  As shown below, the thin films according to Examples 1 to 5 and Comparative Example 1 were prepared, and their physical properties were evaluated.

Example 1
A solution (solution 1) was prepared by dissolving formamidine hydroiodide and lead iodide at 1.33 M and 1.0 M, respectively. Solution 1 was dropped on a quartz plate at room temperature in a nitrogen atmosphere, and a thin film obtained by spin coating at 3000 rpm for 30 seconds was heated at 100 ° C. for 30 minutes. The results of evaluating the samples are shown in Table 1.

(Example 2)
A solution (solution 2) dissolved in DMSO such that formamidine hydroiodide salt and lead iodide are respectively 1.5 M and 1.0 M instead of solution 1 of Example 1 is used. , Prepared and evaluated as in Example 1. The results of evaluating the samples are shown in Table 1.

(Example 3)
A solution (solution 3) dissolved in DMSO so that formamidine hydroiodide salt and lead iodide are respectively 2.0 M and 1.0 M instead of solution 1 of Example 1 is used , Prepared and evaluated as in Example 1. The results of evaluating the samples are shown in Table 1.

(Example 4)
A solution (solution 4) dissolved in DMSO so that formamidine hydrogen iodide salt and lead iodide are respectively 2.5 M and 1.0 M instead of solution 1 of Example 1 is used , Prepared and evaluated as in Example 1. The results of evaluating the samples are shown in Table 1.

(Example 5)
A solution (solution 5) dissolved in DMSO so that formamidine hydroiodide and lead iodide become 3.0 M and 1.0 M, respectively, instead of solution 1 in Example 1 is used. , Prepared and evaluated as in Example 1. The results of evaluating the samples are shown in Table 1.

(Comparative example 1)
The same method as in Example 1 was used except that a solution (solution 6) in which DMSO was dissolved so that formamidine hydroiodide salt and lead iodide each become 1 M instead of solution 1 in Example 1 was used. Prepared and evaluated. The results of evaluating the samples are shown in Table 1.

  From the results of Examples 1 to 5, it is understood that all of the compounds obtained have a crystal structure with a maximum d value of 8 Å or more and a small number of cations having a band gap, and the uniformity of the performance is excellent. It has been shown that it is excellent in light absorption characteristics and excellent in operation stability, and can be suitably used as a semiconductor material such as a solar cell material, an optical sensor, a light emitting material and the like.

  From comparison of the results of Examples 1 to 5 and Comparative Example 1, by making the constituent cations and anions into a predetermined molar ratio, the maximum d value can be made to have a crystal structure of 8 Å or more, and the uniformity of performance can be obtained. It was shown that it became excellent. Moreover, it was shown that this maximum d value becomes larger by setting it as the molar ratio of Examples 1-4.

  From the comparison of the results of Examples 1 to 5 and Comparative Example 1, it was shown that the absorption edge has a long wavelength and the band gap is reduced by setting the constituent cations and anions to a predetermined molar ratio. In particular, it was shown that the band gap can be reduced by decreasing the molar ratio of the counter cation and increasing the molar ratio of the Group 14 cation within the range of the present embodiment.

(Example 6)
Instead of the quartz plate of Example 3, on the FTO surface of a glass on which 25 mm square FTO (fluorine-doped tin oxide) is deposited, a 50 nm dense layer of TiO ₂ as an electron transport material and further a particle diameter of 30 nm Using a substrate (TiO ₂ / FTO glass) on which TiO ₂ particles are deposited and a porous film layer with a film thickness of 800 nm which has been treated with TiCl ₄ is deposited, solution 3 is dropped on the substrate, and spins for 30 seconds at 3000 rpm The thin film obtained by coating is heated at 100 ° C. for 30 minutes, and after cooling to room temperature, 0.0059 mmol of spiro-OMETAD, 0.0317 mol of LiTFSI, 0.0058 mmol of Co (4-t-Butylpyridinyl-2-yl) 1H-pyrazole) 3TFSI solution of 0.195 mmol of t-butylpyridine in chlorobenzene Dropwise 7), it was spin-coated at 4000 rpm, and dried for 30 minutes at 70 ° C.. A cell was obtained by vacuum evaporation of gold from above on the surface at equal intervals and in three places at an area of 0.15 mm ² and a film thickness of 100 nm. The results of evaluation of this cell under pseudo-sunlight irradiation are shown in Table 2.

(Comparative example 2)
The same operation was performed except that Solution 6 was used instead of Solution 3 of Example 6. The results are shown in Table 2.

  From the results of Example 6, it was shown that the compound in the present embodiment can be suitably used as a solar cell material such as a light absorption layer and a light sensor. In particular, it is shown that the solar cell material is remarkably excellent in the short circuit current density and the fill factor as the solar cell material because the light absorption characteristics are excellent and the performance uniformity is excellent by satisfying the present embodiment.

(Example 7)
The sample prepared in Example 3 was heated at 185 ° C. for 30 minutes in a nitrogen atmosphere to obtain a sample. The results are shown in Table 3.

(Comparative example 3)
The procedure of Example 7 was repeated except that the sample of Comparative Example 1 was used instead of the sample prepared in Example 3. The results are shown in Table 3.

  Comparing Example 7 and Comparative Example 3, by heating the compound of this embodiment at a high temperature such as 185 ° C., a compound having a perovskite structure having an absorption edge at a long wavelength of about 820 nm can be prepared with less impurities. It has been shown to be advantageous. That is, it was shown that the compound of the present embodiment is a compound having a perovskite structure and can be suitably used as a precursor of high purity.

Claims (16)

A thin film form of a compound containing a cation and an anion,
10 mol% or more and 49 mol% or less of the cations are Group 14 element cations,
51 mol% or more and 90 mol% or less of the cation is a counter cation, wherein 91 mol% or more and 100 mol% or less of the counter cation is a single kind having 1 or more and 2 or less carbon atoms and nitrogen An organic molecular cation having a number of 2 or more and 4 or less,
30 mol% or more and 100 mol% or less of the anions are Group 17 element anions,
The largest surface spacing in the crystal structure of the compound is 8 Å or more and 30 Å or less,
The nitrogen number of the organic molecule cation is two,
The Group 14 element cation contains lead cation,
The organic molecular cation comprises formamidinium cation,
The Group 17 element anion comprises an iodide anion,
Thin film form of the compound.   The thin film form of the compound according to claim 1, wherein 95 mol% or more and 100 mol% or less of the counter cation is the organic molecular cation.   The thin film form of the compound according to claim 1 or 2, wherein 55 mol% or more and 85 mol% or less of the cations are counter cations.   The thin film form of the compound according to any one of claims 1 to 3, wherein 15 mol% or more and 45 mol% or less of the cations is a 14th element cation.   The thin film form of the compound according to any one of claims 1 to 4, wherein 55 mol% or more and 100 mol% or less of the anion is a Group 17 element anion. Wherein the compound is _{(CH (NH 2) 2)} 2 PbX 4 ( wherein, X is I.) Is a compound represented by the thin form of a compound according to any one of claims 1 to 5 . Wherein the compound is _{(CH (NH 2) 2)} 3 PbX 5 ( wherein, X is I.) Is a compound represented by the thin form of a compound according to any one of claims 1 to 5 .   The thin film form of the compound according to any one of claims 1 to 7, wherein the crystal structure of the compound is a perovskite structure. A method for producing a thin film form of the compound according to any one of claims 1 to 8, comprising
Heating the composition containing the aprotic polar organic solvent, the group 14 element cation, the organic molecule cation, and the group 17 element anion at a temperature of 0 ° C. or more and 160 ° C. or less,
The content of the group 14 element cation in the composition is 0.05 mol / L to 3.0 mol / L, and the content of the organic molecular cation is 0.05 mol / L to 3.0 The manufacturing method of the thin film form of a compound which is mol / L or less and whose content of the said 17th group element anion is 0.05 mol / L or more and 10.0 mol / L or less.   The thin film of the compound according to claim 9, wherein the ratio of the organic molecular cation to the group 14 element cation (organic molecule cation / group 14 element cation) contained in the composition is 1.1 or more and 4 or less. Form of production method.   Use of the compound according to any one of claims 1 to 8 as a semiconductor material in thin film form.   The use as a solar cell material of the thin film form of the compound of any one of Claims 1-8.   Use of the compound according to any one of claims 1 to 8 as a light absorbing layer in a thin film form of a solar cell.   Use of the compound according to any one of claims 1 to 8 as a thin film form of an optical sensor.   Use of the compound according to any one of claims 1 to 8 as a luminescent material in the form of a thin film. A thin film form of a compound according to claim 6, having a perovskite structure _{(CH (NH 2) 2)} PbX 3 ( wherein, X is I.) Used as precursors.