JP6430437B2 - Aggregation - Google Patents

Description

  The present invention relates to an assembly, a method for producing the same, and use thereof.

In recent years, organic inorganic metal halides have attracted attention for various applications. In particular, application of this material as a light emitting material has been proposed. For example, Non-Patent Document 1 describes that a compound comprising a methylammonium cation, a lead cation (Pb ²⁺ ), and a halogen anion is used as a light emitting material.

In Non-Patent Document 2, particles having a size of about 4 nm to 12 nm made of cesium cation (Cs ⁺ ), lead cation (Pb ²⁺ ), and bromine (Br) anion are used as the light emitting material. Is described. Further, this particle was heated to a temperature of 140 ° C. to 200 ° C., mixed with a mixed solution of octadecene in which lead halide was dissolved, oleic acid, and oleylamine, with a cesium oleate solution having a molar ratio of Pb: It can be prepared by a method of pouring so that Cs: Br = 10: 1: 20, and a crystal structure that shares the apex of an octahedron in which a halogen cation is six-coordinated to a lead cation is formed preferentially. Is disclosed.

ACS NANO 2015, 9, 4533. Nano Lett. 2015, 15, 3692.

  However, the compounds described in Non-Patent Document 1 and Non-Patent Document 2 do not have sufficient durability against light emission, and development of materials that are more excellent in light emission durability is required.

  This invention is made | formed in view of the subject which said prior art has, and aims at providing the aggregate | assembly which is excellent in light emission durability, and its manufacturing method.

  As a result of intensive studies and experiments to solve the above-described problems of the prior art, the present inventors have obtained the above problem by forming an aggregate of particles containing a predetermined cation and a predetermined anion and having a predetermined crystal structure. Has been found to be able to be solved, and the present invention has been completed.

That is, the present invention is as follows.
[1]
An assembly of crystalline particles comprising a cation and an anion,
10 mol% or more and 95 mol% or less of the cation is a Group 14 element cation,
5 to 90 mol% of the cation is a counter cation, wherein the counter cation includes an organic molecular cation in which the sum of carbon and nitrogen constituting one molecule is 3 to 20;
30 mol% or more and 100 mol% or less of the anion is a group 17 element anion,
The crystalline particles have an octahedral structure in which the Group 17 element anion is six-coordinated to the Group 14 cation;
The crystalline particles include crystalline particles (A) having a crystal structure in which at least a part of the octahedral structure is face-sharing,
The aggregate | assembly whose average particle diameter of the said crystalline particle is 0.1 nm or more and 200 nm or less.
[2]
The aggregate according to [1], wherein the crystalline particles include a plurality of crystal phases.
[3]
The aggregate according to [1] or [2], wherein the crystalline particle includes a crystalline particle (B) having a crystal structure in which at least a part of the octahedral structure shares a vertex.
[4]
The aggregate according to any one of [1] to [3], wherein the crystalline particles (A) include crystalline particles (C) having a hexagonal crystal structure.
[5]
The aggregate according to any one of [1] to [4], wherein 20 mol% or more and 85 mol% or less of the cation is a Group 14 element cation.
[6]
The aggregate according to any one of [1] to [5], wherein the group 14 element cation is a Sn cation or a Pb cation.
[7]
The aggregate according to any one of [1] to [6], wherein 10 mol% or more and 80 mol% or less of the cation is a counter cation.
[8]
The aggregate according to any one of [1] to [7], wherein the sum of carbon and nitrogen constituting one molecule of the organic molecular cation is 3 or more and 11 or less.
[9]
The aggregate according to any one of [1] to [8], wherein the organic molecular cation is a formamidine cation.
[10]
The aggregate according to any one of [1] to [9], wherein 55 mol% or more and 100 mol% or less of the anion is at least one selected from the group consisting of a chlorine anion, a bromine anion, and an iodine anion.
[11]
The aggregate according to any one of [1] to [10], wherein the Group 17 element anion includes at least one selected from the group consisting of a chlorine anion, a bromine anion, and an iodine anion.
[12]
The aggregate according to any one of [1] to [11], wherein the particle diameter is 1 nm or more and 100 nm or less.
[13]
[1] to [12] A method for producing an aggregate according to any one of
A method for producing an aggregate, comprising a step of crystal formation and / or crystal growth at 0 ° C. or higher and 50 ° C. or lower.
[14]
[1] to [12] A method for producing an aggregate according to any one of
Adding a solution containing a salt of an organic base and a hydrogen halide, a Group 14 element halide, and a first solvent to the second solvent;
The first solvent is a good solvent for the salt and the Group 14 element halide;
The method for producing an aggregate, wherein the second solvent is a poor solvent for the salt and the Group 14 element halide.
[15]
Use of the aggregate according to any one of [1] to [12] as a luminescent material.
[16]
Use of the aggregate according to any one of [1] to [12] as a thin film precursor.

  The aggregate according to the present invention is excellent in light emission durability.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The following embodiments are examples for explaining the present invention, and are 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.

  The aggregate according to the present embodiment is an aggregate of crystalline particles containing a cation and an anion, wherein 10 mol% or more and 95 mol% or less of the cation is a Group 14 element cation, and 5 mol of the cation. % To 90 mol% is a counter cation, wherein the counter cation includes an organic molecular cation in which the sum of carbon and nitrogen constituting one molecule is 3 to 20, and 30 mol% or more of the anion. 100 mol% or less is a Group 17 element anion, the crystalline particle has an octahedral structure in which the Group 17 element anion is six-coordinated to the Group 14 cation, and the crystalline particle is Crystalline particles (A) having a crystal structure in which at least a part of the octahedral structure is face-sharing are included, and the average particle diameter of the crystalline particles is 0.1 nm to 200 nm. Since it is comprised in this way, the aggregate | assembly which concerns on this embodiment is excellent in light emission durability.

(Crystalline particles)
The crystalline particle in this embodiment contains a cation and an anion. Moreover, in this embodiment, 10 mol% or more and 95 mol% or less of the said cation are Group 14 element cations with respect to the total amount (100 mol%) of the cation contained in the said crystalline particle. From the viewpoint of being advantageous for light absorption properties and / or having a higher density of states for forming a valence band and a conduction band, the group 14 element cation is preferably 20 mol% or more, more preferably 30 mol%, More preferred is mol%. Increasing the extinction coefficient is advantageous for the aggregate to efficiently absorb the irradiated light, and increasing the density of states is advantageous for increasing the extinction coefficient. Also, from the viewpoint of forming a crystal structure in which the octahedral structure composed of the cation and the anion can contain a large amount of counter cations and is face-sharing, it is preferably 85 mol% or less, and 75% The following is more preferable, and 65 mol% or less is more preferable. The amount of the group 14 element cation with respect to the cation can be obtained as a value obtained by analyzing the aggregate by ICP or the like, as described in Examples below.

The group 14 cation is not particularly limited, and examples thereof include Si ⁴⁺ , Ge ²⁺ , Ge ⁴⁺ , Sn ²⁺ , Sn ⁴⁺ , and Pb ²⁺ . In this embodiment, from the viewpoint of advantageous for the formation of an octahedral structure of the Group 14 cation and the Group 17 element anion, by increasing the covalent bond between the Group 14 cation and the anion, A divalent cation is preferable from the viewpoint of increasing the density of states, and specifically, Ge ²⁺ , Sn ²⁺ , Pb ^{2+ and the} like are preferable. Furthermore, from the viewpoint of being relatively stable against oxidation, Sn ²⁺ and Pb ²⁺ are more preferable, and Pb ²⁺ is more preferable.

  Among the cations contained in the crystalline particles in the present embodiment, 5 mol% or more and 90 mol% or less of cations other than the group 14 element and the cations after the third period (also referred to as “counter cation” in the present specification) ) Is included. By including a counter cation, the arrangement of the group 14 element cations can be controlled. By controlling the arrangement of the group 14 element cations, thermal relaxation of the photoexcited carriers is further suppressed, which tends to be advantageous for light emission and generation of photovoltaic power. From the viewpoint of being advantageous for the arrangement of the Group 14 element cations, the counter cation contained in the crystalline particles is preferably 10 mol% or more, more preferably 20 mol% or more, and further preferably 30 mol% or more. Further, from the viewpoint of containing a large amount of the Group 14 element cation, it is preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 60 mol% or less. The amount of the counter cation with respect to the cation can be obtained as a value obtained by analyzing the aggregate by ICP or the like, as described in Examples described later.

  In the present embodiment, the counter cation includes an organic molecular cation in which the sum of carbon and nitrogen constituting one molecule is 3 or more and 20 or less. Including an organic molecular cation is important from the viewpoint of making the crystalline particles more flexible and from the viewpoint of facilitating crystallization. In this specification, an organic molecule refers to a molecule containing carbon as a constituent element. Further, the sum of carbon and nitrogen constituting one organic molecular cation being 3 or more is a viewpoint of improving at least one of heat resistance and oxidation resistance as compared with the case where the sum is 2 or less, and / or Alternatively, it is important from the viewpoint of improving durability against light emission. In addition, when the sum of carbon and nitrogen constituting one organic molecular cation is 20 or less, the viewpoint of carrier mobility in the crystal and the electronic state of the group 14 element cation are more delocalized. Important from the point of view.

  The organic molecular cation contained in the counter cation constituting the crystalline particles is advantageous in that it is advantageous for the carrier movement in the crystal and the delocalization of the electronic state of the group 17 element cation. The sum of carbon and nitrogen constituting the molecule is preferably 11 or less, and more preferably 8 or less. From the viewpoint of making the crystalline particles more flexible, the number of carbon atoms constituting one molecule is preferably 1 or more. The number of carbon atoms constituting one molecule is preferably 10 or less, and preferably 5 or less, from the viewpoint of advantageous for moving carriers in crystals and delocalizing the electronic state of group 14 element cations. Further preferred. Moreover, the number of nitrogen atoms constituting one molecule is preferably 2 or more from the viewpoint that the cationic property of the organic molecular cation can be further increased and the effective ion radius can be increased. From the viewpoint of being advantageous for delocalizing the electronic state of the crystal, the number of nitrogen constituting one molecule is preferably 20 or less, and more preferably 5 or less. In addition, an organic molecule having high symmetry and / or having a conjugated unsaturated bond is preferable from the viewpoint of not distorting the crystal structure of the composition.

  From the viewpoint of imparting flexibility to the crystalline particles and facilitating crystallization, the organic molecular cation contained in the counter cation is preferably 30 mol% or more, more preferably 50% or more, and even more preferably 80% or more. The amount of the organic molecular cation relative to the counter cation can be obtained as a value obtained by analyzing the aggregate by ICP or the like, as described in the examples described later.

  Specific examples of the counter cation including an organic molecule in which the sum of carbon and nitrogen constituting one molecule is 3 or more and 20 or less are not limited to the following, but include ethyl ammonium cation, propyl ammonium cation, butyl ammonium cation, penta Ammonium cation, hexaammonium cation, dimethylammonium cation, diethylammonium cation, dipropylammonium cation, trimethylammonium cation, triethylammonium cation, formamidine cation, acetamidine cation, guanidine cation, imidazole cation, aniline cation, and isomers thereof Etc. The larger the molecular size, the more advantageous the durability such as heat resistance, oxidation resistance, and durability against light emission, from the viewpoint of durability such as butyl ammonium cation, penta ammonium cation, hexa ammonium cation, dimethyl ammonium cation, diethyl ammonium cation, dipropyl. Ammonium cation, trimethylammonium cation, triethylammonium cation, formamidine cation, acetamidine cation, guanidine cation, imidazole cation, aniline cation, and their isomers are preferred. From the viewpoint of being advantageous for durability such as heat resistance, oxidation resistance, and durability against light emission, formamidine cation, acetamidine cation, guanidine Thion, imidazole cation, aniline cation, and isomers thereof are more preferable, and the smaller the effective ionic radius, the more preferable are formamidine cation, acetamidine cation, and guanidine cation from the viewpoint of densely arranging group 14 element cations. A formamidine cation is even more preferable.

  In this embodiment, the crystalline particles contain a Group 17 element anion of 30 mol% or more and 100 mol% or less with respect to the total amount (100 mol%) of anions contained in the crystalline particles. It is important to contain 30 mol% or more from the viewpoint of containing more Group 17 element anions and increasing the ionic bondability between cations and anions in the crystalline particles, which is advantageous for crystal formation. From the viewpoint of increasing the ionic bondability of the crystal, the Group 17 element anion is preferably contained in an amount of 55 mol% or more, more preferably 75% or more. Specific group 17 elements are not particularly limited, but examples include iodine, bromine, chlorine, fluorine, etc., and iodine, bromine, and chlorine are preferable from the viewpoint of being advantageous for common bonding properties. Bromine is more preferred from the viewpoint of being advantageous. The amount of the Group 17 element anion with respect to the anion can be obtained as a value obtained by analyzing the aggregate by ICP or the like, as described in Examples described later.

  In the present embodiment, the crystal structure of at least some of the crystalline particles contained in the aggregate has an octahedral structure in which the Group 17 element anion is six-coordinated to the Group 14 element cation. Furthermore, the crystalline particles in the present embodiment include crystalline particles (A) having a crystal structure in which at least a part of the octahedral structure is shared. In the present embodiment, the octahedral structure is shared so that durability, particularly durability against light emission, is improved. From the viewpoint of being particularly effective in improving durability against light emission, the crystalline particles (A) having a crystal structure in which the octahedral structure is shared include crystalline particles (C) having a hexagonal crystal structure. It is preferable. The aggregate can include particles of other crystalline phases. Examples of the other crystal phase include a crystal structure sharing the apex of the octahedral structure. That is, the crystalline particles in the present embodiment can include crystalline particles (B) having a crystal structure in which at least a part of the octahedral structure has a shared apex. These crystal structures can be evaluated by crystal structure analysis by X-ray diffraction or a lattice image of a transmission electron microscope image. The mixing ratio of the crystalline particles (C) and the crystalline particles (B) is the diffraction peak derived from the (0001) plane of the crystalline particles (C) in the XRD pattern of the aggregate, and the crystalline particles (B The ratio of the peak intensity with respect to the diffraction peak derived from the (110) plane of (110) plane (crystalline particles (B) / crystalline particles (C)) is preferably 1 or more, and more preferably 10 or more. Further, the ratio of the peak intensities (crystalline particles (B) / crystalline particles (C)) is preferably 200 or less, and more preferably 50 or less. For the crystalline particles (A), particularly the crystalline particles (C), for example, a step of dissolving a substance containing a predetermined cation and an anion described later together in a solvent to obtain a solution, Crystalline particles (A) and crystalline particles (C) tend to be preferably produced by a production method including a step of adding to a poor solvent at 0 ° C. or lower, and further tend to be in the range of the above blending ratio. is there.

  The band gap of the crystalline particles contained in the aggregate is preferably large from the viewpoint of energy efficiency with respect to the emission wavelength with respect to the absorption wavelength. Specifically, 2.1 eV or more is preferable, and 2.3 eV or more is more preferable. It is preferable that the aggregate has a plurality of crystal phases having different band gaps from the viewpoint that the emission wavelength becomes wide and the light can be easily understood visually. Specifically, a crystalline particle having an octahedral structure in which the Group 17 element anion is six-coordinated to the Group 14 element cation, and at least a part of the octahedral structure is shared. It is preferable that both (A) and crystalline particles (B) having a crystal structure in which at least a part of the octahedral structure has a shared apex are included. In order for the aggregate to include both the crystalline particles (A) and the crystalline particles (B), for example, it is preferable to adjust the temperature so that the temperature at the time of forming the crystals is not too high or too low. Specifically, it is preferable to produce the aggregate at a reaction temperature of 0 ° C. or higher and 50 ° C. or lower.

(Aggregation)
The aggregate in the present embodiment is composed of a plurality of particles including crystalline particles. The number of particles contained in the aggregate is not particularly limited, but typically includes aggregates containing 1000 or more crystalline particles. The number of particles can be measured by various known methods, such as observation with a transmission electron microscope (TEM). The average interparticle distance in the aggregate is calculated from the observation by TEM, the concentration of the crystalline particles existing in the space from the absorption coefficient, the mass, etc., and the concentration, the density of the crystalline particles, and the volume of the space. Although it can confirm by calculating the distance between average particle | grains and it does not specifically limit, Typically, it is about 1-2000 mm. The average particle diameter of the crystalline particles constituting the aggregate is from 0.1 nm to 200 nm. From the viewpoint of being less affected by surface energy, advantageous for suppressing aggregation, and advantageous for reducing the band gap, it is preferably 0.5 nm or more, and more preferably 1 nm or more. Further, from the viewpoint of increasing the band gap and from the viewpoint of improving the emission quantum yield, 100 nm or less is preferable, 50 nm or less is more preferable, and 30 nm or less is more preferable. The average particle diameter can be measured by the method described in the examples described later. For example, the supernatant is separated and recovered by centrifugation performed under a condition such as 7000 rpm with respect to the solution containing the aggregate, and excess by filter paper. The above range can be controlled by a method of removing large particles.

  The form of the particles may be a sphere, a cube, a rectangular parallelepiped, a rod, a plate, or the like. From the viewpoint of reducing the surface energy, a cube, a cuboid, a plate, or a rod is preferable, and a cube or a cuboid is more preferable. The aggregate in the present embodiment can include particles having different forms with respect to the form of the particles. For example, spherical, cubic and rectangular parallelepiped particles can coexist. The morphology of the particles can be confirmed by observation with a TEM.

  The aggregate in the present embodiment can include non-crystalline particles as well as crystalline particles. For example, amorphous particles include amorphous lead halides, salts of organic bases such as amines and acids, and the like. The crystalline particles may be single phase single crystals or particles composed of a plurality of phases.

  It is preferable that the aggregate emits light having a wide wavelength from the viewpoint that light emitted from the aggregate can be easily understood by light having a wide emission wavelength. Specifically, the emission wavelength width is preferably 90 nm or more, and more preferably 120 nm or more.

(Production method of assembly)
Although it does not specifically limit as a manufacturing method of the aggregate | assembly of this embodiment, For example, it can pass through a predetermined | prescribed process using the raw material mentioned later. As a preferable method for producing an aggregate in the present embodiment, an aspect including a step of crystal formation and / or crystal growth at 0 ° C. or more and 50 ° C. or less can be mentioned. And a step of adding a solution containing a salt of an organic base and a hydrogen halide, a Group 14 element halide, and a first solvent to the second solvent, wherein the first solvent comprises: It is also preferable that the salt and the Group 14 element halide are good solvents, and the second solvent is a poor solvent for the salt and the Group 14 element halides.

  As a raw material of the aggregate of the present embodiment, a substance containing a cation element constituting the particles forming the aggregate and a substance containing an anion element constituting it are preferable. In particular, the group 14 element cation can be obtained by including a step of dissolving a substance containing a predetermined cation and an anion together in a solvent to obtain a solution, and a step of adding this solution to a poor solvent at 0 ° C. to 50 ° C. The group 17 element anion is preferable from the viewpoint of having an octahedral structure in which six anions are coordinated, and a structure in which at least a part of the octahedral structure is shared. The reason is not limited to a specific mechanism, but is presumed as follows. That is, any one of the raw material concentration, the temperature, the reaction rate, the solvation, the adsorption state of the ligand, etc., in the reaction field in a very short time (several n seconds to several seconds) for crystal nucleation or crystal growth Alternatively, it is presumed that a crystal structure in which at least a part of the octahedral structure is shared can be formed by the concerted effect of these plural conditions. In particular, in the case of producing an aggregate by a method including the above-described steps, it can be said that the aggregate satisfying the predetermined configuration of the present embodiment can be prepared because it can be said to be a preferable condition from the above viewpoint.

  Regarding the above raw materials, specifically, metal halides, ammonia compounds, salts of organic bases and hydrogen halides are preferably used as raw materials, and the thermal stability of the raw materials and the viewpoint that production is relatively easy Therefore, it is more preferable to use a metal halide. The halogen species constituting the metal halide is preferably a Group 17 element in the periodic table of the new IPAC, and specifically, fluorine, chlorine, bromine, iodine and the like are preferable. Iodine, bromine, and chlorine are preferable and bromine is more preferable from the viewpoint that the smaller the ionic bondability, the more advantageous for bond dissociation.

  Specific examples of the salt of base and hydrogen halide include, but are not limited to, ethylamine / hydrogen iodide, ethylamine / hydrobromide, ethylamine / hydrochloride, propylamine / hydrogen iodide, propyl Amine, hydrobromide, propylamine, hydrochloride, butylamine, hydroiodide, butylamine, hydrobromide, butylamine, hydrochloride, pentaamine, hydroiodide, pentaamine, hydrobromide, pentaamine, Hydrogen chloride, hexaamine / hydrogen iodide, hexaamine / hydrobromide, hexaamine / hydrogen chloride, ammonia / hydrogen iodide, dimethylamine / hydrogen iodide, dimethylamine / hydrobromide, dimethylamine / Hydrogen chloride, diethylamine / hydrogen iodide, diethylamine / hydrobromide, diethylamine / chloride Elementary salt, dipropylamine / hydrogen iodide, dipropylamine / hydrobromide, dipropylamine / hydrochloride, trimethylamine / hydrogen iodide, trimethylamine / hydrobromide, trimethylamine / hydrochloride, triethylamine・ Hydroiodide salt, triethylamine / hydrobromide, triethylamine / hydrochloride, formamidine / hydrochloride, formamidine / hydroiodide, formamidine / hydrobromide, acetamidine / hydrochloride, aceto Amidine / hydrogen iodide, acetamidine / hydrobromide, guanidine / hydrochloride, guanidine / hydroiodide, guanidine / hydrobromide, imidazole / hydrochloride, imidazole / hydroiodide, imidazole / Hydrobromide, aniline / hydrobromide, aniline / hydrochloride, etc. And more specifically, formamidine-hydrochloride salt, formamidine-hydroiodide, and the like formamidine-hydrobromide.

  The assembly of this embodiment is preferably produced using a solution in which a substance containing a predetermined cation and an anion is dissolved in a solvent. When crystalline particles are produced and aggregates are prepared by dissolving a predetermined cation and anion in separate solutions and mixing them, an octahedral structure in which the Group 17 element anion is six-coordinated to the Group 14 element cation is obtained. The solvent contains a predetermined cation and an anion from the viewpoint of being disadvantageous in forming a surface-shared structure, from the viewpoint of generating a large amount of impurities, and / or from the viewpoint of remaining a large amount of raw materials in the solution. Both substances are preferably produced using a dissolved solution.

  The predetermined cation and anion contained in the solution are preferably contained in a composition close to the stoichiometry of the target product. For example, formamidine cation, lead (Pb) cation, and bromine (Br) anion are preferably contained in the solution at 1: 1: 3.

  The solvent is preferably an aprotic organic solvent from the viewpoint of being advantageous for dissolving the Group 14 element halide as a raw material. Specifically, dimethylformamide (hereinafter referred to as DMF), dimethyl sulfoxide, γ-butyrolactone and the like are preferable, and DMF and γ-butyrolactone are more preferable from the viewpoint of excellent precipitation of the particles. Examples of the poor solvent for the Group 14 element halide include, but are not limited to, dimethyl ether, diethyl ether, chlorobenzene, toluene, and the like.

  From the viewpoint of reducing the particle size contained in the aggregate, the solution preferably contains a crystal growth inhibitor. Although it does not specifically limit as a crystal growth inhibitor, For example, carboxylic acid etc. are mentioned, Specifically, the carbon number which comprises 6 or more and 30 or less is mentioned, More specifically, the following is mentioned. Although not limited thereto, for example, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, oleic acid and the like can be mentioned, and octadecanoic acid and oleic acid are preferable.

  The solvent preferably contains a ligand from the viewpoint of preventing particle aggregation and crystal growth. Specific examples include organic amines and phosphines. Specific examples include organic amines having 6 to 30 carbon atoms and phosphines, and more specific examples include trioctylphosphine, octylamine, and oleylamine.

  In this embodiment, it is preferable to produce an aggregate by reacting a solution obtained by dissolving the raw material in a good solvent of the raw material with a poor solvent of the raw material. The poor solvent is preferably a nonpolar solvent from the viewpoint of preventing aggregation of the particle aggregating agent and the particles adsorbed with the ligand. Specific examples include, but are not limited to, toluene, chlorobenzene, hexane, and the like.

  The temperature for crystal formation and / or crystal growth contained in the aggregate, for example, the temperature at which the solution in which the raw material is dissolved in the solvent is reacted with a poor solvent is preferably 0 ° C. or higher and 50 ° C. or lower. From the viewpoint of avoiding an excessive increase in the viscosity of the solution, 0 ° C. or higher is preferable. In addition, from the viewpoint of easily forming a structure in which the group 14 element cation has an octahedral structure in which the group 17 element anion is six-coordinated and at least a part of the octahedral structure is shared. It is preferably at most 0 ° C, more preferably at most 40 ° C, further preferably at most 30 ° C.

  Aggregates obtained by reacting a solution obtained by dissolving the raw material in a good solvent for the raw material with a poor solvent for the raw material form a denser thin film from the viewpoint of increasing the emission quantum yield by performing a separation operation. From the viewpoint of being able to. Examples of the separation operation include centrifugation and filtration.

(Use of aggregate)
The aggregate in the present embodiment is not limited to a specific application and can be used in various applications. For example, it can be used as a light emitting material, an optical sensor, or the like. From the viewpoint of excellent durability against light emission, use as a light emitting material is preferable. Moreover, it can utilize also as a material for setting it as a different form, for example, utilization as a precursor of a thin film etc. are mentioned.

  Hereinafter, the present embodiment will be described more specifically with specific examples and comparative examples. However, the present embodiment is not limited to these examples and comparative examples unless they exceed the gist thereof. Absent. The physical properties, reaction conditions, and product identification in Examples and Comparative Examples described later were measured and set by the following methods.

(Cation content and anion content)
The group 14 cation amount, the organic molecule cation amount, and the halogen anion amount contained in the aggregate were determined by measuring the aggregate in the supernatant liquid obtained by performing centrifugation described later with SEM-EDX (SEM: SU-70, It was determined by evaluation using Hitachi, Ltd., EDX: EMAX X-max, manufactured by Horiba Ltd.

(Crystal structure, crystal phase)
A crystal structure of the crystalline particles constituting the aggregate, and an octahedral structure in which the group 17 element anion is six-coordinated to the group 14 element cation, and at least a part of the octahedral structure is shared. The existence of a structure (hereinafter referred to as a surface-shared phase) was evaluated from an X-ray diffraction (XRD) pattern measured using an X-ray diffractometer (D8, manufactured by Bruker).

(Average particle size, particle morphology)
The particle size and particle morphology of the crystalline particles constituting the aggregate were determined by measuring at an acceleration voltage of 200 kV using a transmission electron microscope (H-9000NAR, manufactured by Hitachi High-Technologies). The average particle size was calculated from the average value of the particle sizes obtained by the above method for any five or more particles.

(Peak emission wavelength, emission wavelength range)
Luminescence measurement was carried out using a luminescence measuring device (C9920-02, manufactured by Hamamatsu Photonics Co., Ltd.) for a liquid whose concentration was adjusted by diluting with toluene so that the absorbance at the peak top of the solution containing the aggregate was 0.1. The emission peak wavelength and the emission wavelength range were respectively determined from the peak wavelength of the emission spectrum when excited at an excitation wavelength of 350 nm in the atmosphere and the difference between the emission rising wavelength and the falling wavelength.

(Luminescence decay rate)
The luminescence decay rate is measured using the solution containing the aggregate prepared at the above concentration and the luminescence measurement device, and the first measurement value and the fifth measurement value are used for the following quantum yield. The emission decay rate was calculated from the following equation. After the third measurement, the solution was bubbled with dry nitrogen gas for 10 minutes. It shows that durability with respect to light emission is so high that a light emission attenuation factor is small.
(Quantum yield) = (Total number of photons emitted from the solution) / (Number of photons absorbed in the solution)
(Luminescence decay rate) = 1 − ((Quantum yield at the fifth measurement) / (Quantum yield at the first measurement))

(Mixing ratio)
The blending ratio ((B) / (C)) of the crystalline particles (B) and the crystalline particles (C) of the aggregate is the hexagonal (0001) plane of the crystalline particles (C) in the XRD pattern. It was determined from the intensity ratio of the diffraction peak derived from the diffraction peak and the diffraction peak derived from the (110) plane of the crystalline particle (B).

  As shown below, the assembly which concerns on Example 1 and Comparative Examples 1-2 was prepared, and the physical property was evaluated.

(Example 1)
Formamidine hydrobromide (CH ₄ N ₂ .HBr) and lead bromide (PbBr ₂ ) dissolved in DMF to a concentration of 0.04 mol / L was added to 0.5 mL of 0.5 mL of oleic acid and 20 μL. A solution (solution 1) to which n-octylamine was added was prepared. That is, a raw material solution in which a counter cation source of crystalline particles, a group 14 cation and a group 17 anion source were mixed was prepared. 2 mL of Solution 1 in nitrogen at 10 ° C. was added dropwise to 10 mL of toluene at a rate of 1 mL / min, and the resulting solution was diluted to 50 mL with toluene and centrifuged at 7000 rpm, and the supernatant containing the aggregate ( Luminescence measurement was performed using solution 2). Moreover, 0.5 mL acetone was added to this solution 2, and the crystal structure of the precipitate obtained by centrifuging was evaluated by XRD. A hexagonal crystal structure was observed in which the octahedron of Pb cation and Br anion shared at 2θ = 12 °. The results are shown in Table 1.

<Comparative Example 1>
An assembly solution was prepared and evaluated using a solution (solution 3) using methylamine hydrobromide instead of the formamidine hydrobromide of solution 1. From the XRD pattern, a crystal structure in which the octahedrons of the Pb cation and the Br anion were shared was not observed. The results are shown in Table 1.

<Comparative Example 2>
A solution (solution 4) was prepared by dissolving cesium carbonate in a solution obtained by mixing oleic acid and octadecene at a volume ratio of 1:16 at 150 ° C. in nitrogen so as to be 0.017 mol / L. A solution (solution 5) in which lead bromide was dissolved to a concentration of 0.027M in a solution in which oleic acid, oleylamine, and octadecene were mixed at a volume ratio of 1: 1: 30 was prepared. That is, a raw material solution serving as a counter cation source for the crystalline particles and a raw material solution serving as a group 14 cation and a group 17 anion source were prepared separately. To 13 mL of the solution 5 heated to 140 ° C., 0.8 mL of the solution 4 heated to 50 ° C. was dropped, and then ice-cooled. It took 30 seconds from addition of solution 4 to ice cooling. Evaluation was performed in the same manner as in Example 1 using a solution diluted with toluene as the ice-cooled solution. The results are shown in Table 1.

  From the comparison of the XRD results of Example 1 and Comparative Examples 1 and 2, the assembly prepared according to the preferred preparation conditions of this embodiment has the predetermined composition of this embodiment, and is composed of eight Pb cations and Br anions. It was found that the face pieces have a crystal structure with face-sharing.

  Both the samples of Example 1 and Comparative Examples 1 and 2 showed luminescence, indicating that they can be used as luminescent materials. When the emission wavelength was compared between Example 1 and Comparative Examples 1 and 2, it was found that by satisfying the predetermined configuration of the present embodiment, the emission peak was at a short wavelength and the emission wavelength range was widened.

  When the light emission attenuation rate of Example 1 and Comparative Examples 1 and 2 was evaluated, the light emission was not attenuated in Example 1, but was greatly attenuated in Comparative Examples 1 and 2. From this result, it was shown that an assembly having high durability against light emission can be obtained by satisfying the predetermined configuration of the present embodiment.

Claims (13)

An assembly of crystalline particles comprising a cation and an anion,
10 mol% or more and 95 mol% or less of the cation is a Group 14 element cation,
5 to 90 mol% of the cation is a counter cation, wherein the counter cation includes an organic molecular cation in which the sum of carbon and nitrogen constituting one molecule is 3 to 20;
30 mol% or more and 100 mol% or less of the anion is a group 17 element anion,
The crystalline particles have an octahedral structure in which the Group 17 element anion is six-coordinated to the Group 14 cation;
The crystalline particles include crystalline particles (A) having a crystal structure in which at least a part of the octahedral structure is face-sharing,
The average particle diameter of the crystalline particles is 0.1 nm or more and 200 nm or less,
The Group 14 element cation is a Sn cation or a Pb cation;
The organic molecular cation is a formamidine cation,
The assembly wherein the group 17 element anion includes at least one selected from the group consisting of a chlorine anion, a bromine anion and an iodine anion.   The aggregate according to claim 1, wherein the crystalline particles include a plurality of crystal phases.   The aggregate according to claim 1 or 2, wherein the crystalline particles include crystalline particles (B) having a crystal structure in which at least a part of the octahedral structure has a shared apex.   The aggregate according to any one of claims 1 to 3, wherein the crystalline particles (A) include crystalline particles (C) having a hexagonal crystal structure.   The aggregate according to any one of claims 1 to 4, wherein 20 mol% or more and 85 mol% or less of the cation is a Group 14 element cation. The aggregate according to any one of claims 1 to 5 , wherein 10 to 80 mol% of the cation is a counter cation. The aggregate according to any one of claims 1 to 6 , wherein a sum of carbon and nitrogen constituting one molecule of the organic molecular cation is 3 or more and 11 or less. The aggregate according to any one of claims 1 to 7 , wherein 55 mol% or more and 100 mol% or less of the anion is at least one selected from the group consisting of a chlorine anion, a bromine anion, and an iodine anion. The aggregate according to any one of claims 1 to 8 , wherein the particle diameter is 1 nm or more and 100 nm or less. A method of manufacturing a assembly according to any one of claims 1 to 9
A method for producing an aggregate, comprising a step of crystal formation and / or crystal growth at 0 ° C. or higher and 50 ° C. or lower. It is a manufacturing method of the aggregate according to any one of claims 1 to 9 ,
Adding a solution containing a salt of an organic base and a hydrogen halide, a Group 14 element halide, and a first solvent to the second solvent;
The first solvent is a good solvent for the salt and the Group 14 element halide;
The method for producing an aggregate, wherein the second solvent is a poor solvent for the salt and the Group 14 element halide. Use of the aggregate according to any one of claims 1 to 9 as a luminescent material. Use of the aggregate according to any one of claims 1 to 9 as a thin film precursor.