WO2017085831A1

WO2017085831A1 - Luminescent object and production process therefor

Info

Publication number: WO2017085831A1
Application number: PCT/JP2015/082541
Authority: WO
Inventors: 望月　誠
Original assignee: コニカミノルタ株式会社
Priority date: 2015-11-19
Filing date: 2015-11-19
Publication date: 2017-05-26

Abstract

The purpose of the present invention is to provide a luminescent object including carbon-dot-containing particles which has a high quantum yield, evenness of fluorescence intensity, and a long luminescence life and which emits fluorescence having a high color purity. In order to achieve the purpose, a luminescent object is configured so as to include carbon-dot-containing particles which each comprise one or more carbon dots and an insulating material which covers the carbon dots, the carbon dots having a coefficient of variation in particle diameter of 20% or less.

Description

Luminescent body and manufacturing method thereof

The present invention relates to a light emitter and a method for manufacturing the same.

Conventionally, it is known that a fluorescent material excited by light of a specific wavelength is used for a wavelength conversion layer of various lighting devices, a labeled probe for fluorescently labeling a specific biological substance, or the like. As such a fluorescent material, an organic dye is generally used. However, organic dyes have low light resistance, and have problems such as deterioration due to irradiation with excitation light over a long period of time and reduction in fluorescence intensity.

On the other hand, it has been studied to use quantum dots, which are inorganic semiconductor materials, as fluorescent materials. Quantum dots are excellent in light resistance and have an advantage that the fluorescence intensity is hardly lowered even when irradiated with excitation light for a long period of time. However, among such quantum dots, those exhibiting a high quantum yield often contain cadmium and indium, and there have been problems in terms of influence on the living body and consideration for the environment.

Therefore, the use of carbon phosphors such as carbon nanoparticles (carbon dots) and graphene nanosheets as a phosphor material is also being studied. The carbon phosphor does not contain cadmium, indium or the like, and hardly affects the living body or the environment. The carbon phosphor also has an advantage of high light resistance. However, carbon phosphors may not have sufficient emission lifetime and quantum yield, and these improvements have been demanded.

Here, Patent Document 1 discloses forming a layer made of an insulator on the surface of the graphene sheet as a method for increasing the quantum yield of the graphene nanosheet which is a carbon phosphor. On the other hand, in Non-Patent Document 1, as a method for efficiently producing carbon dots, a carbon compound is injected into pores of porous silica having pores, and the carbon compound is sintered in the pores of porous silica. It has been shown to tie. According to the manufacturing method of Non-Patent Document 1, a light emitter in which carbon dots are accommodated in the pores of porous silica can be obtained.

JP 2013-023670 A

According to the technique of the above-mentioned Patent Document 1, it is assumed that the emission lifetime and the quantum yield can be somewhat increased because the insulator suppresses the excitation electrons from flowing out of the graphene sheet to some extent. However, in the technique of Patent Document 1, the insulator is easily peeled off at the end of the graphene sheet, and it has been difficult to sufficiently increase the light emission lifetime and the quantum yield. Moreover, in the technique of patent document 1, it is difficult to make uniform the size of the graphene sheet which each light-emitting body (laminated body of a graphene sheet) contains. Therefore, the fluorescence intensity emitted from each light emitter tends to vary. In addition, since the color purity of the fluorescence obtained from the illuminant is low, there is a problem that its use is limited.

On the other hand, in the luminous body in which carbon dots are accommodated in the pores of porous silica obtained by the technique of Non-Patent Document 1, many surfaces of carbon dots are exposed from porous silica that is an insulator. As a result, there has been a problem that the light emission lifetime and the quantum yield are not sufficiently increased.

The present invention has been made in view of the above problems. That is, an object of the present invention is to provide a light emitter including a carbon dot inclusion body having a high quantum yield, uniform fluorescence intensity, high color purity of emitted fluorescence, and a long emission lifetime.

That is, the first of the present invention is the following light emitter.
[1] A light emitting body including a carbon dot inclusion body having carbon dots and an insulator covering the carbon dots, and a variation coefficient of a particle size of the carbon dots is 20% or less.
[2] The carbon dot inclusion body is a carbon dot single inclusion particle in which the carbon dot is covered with the insulator, and the light emitter is in a powder form or a slurry form. Luminous body.
[3] The carbon dot inclusion body is a carbon dot multiple inclusion body in which two or more carbon dots are coated with the insulator, and the luminous body is in a powder form, a slurry form, or a bulk form. 1].

[4] The luminous body according to any one of [1] to [3], wherein a ratio (b / a) between a short diameter a and a long diameter b of the carbon dots is in a range of 1.0 to 1.5. .
[5] The light emitter according to any one of [1] to [4], wherein the carbon dots and the insulator are chemically bonded at an interface between the carbon dots and the insulator.
[6] The light emitter according to [5], wherein the chemical bond is an amide bond.
[7] The light emitter according to any one of [1] to [6], wherein the insulator includes a metalloxane bond.

The second of the present invention lies in the following method for producing a light emitter.
[8] The method for producing a luminescent material according to any one of [1] to [7], wherein the carbon dots are obtained by sintering a carbon compound in the pores of mesoporous silica; Covering the carbon dots with the insulator.

The carbon dot inclusion body included in the light emitter of the present invention has a high quantum yield and a uniform fluorescence intensity. Moreover, the color purity of the fluorescence emitted from the carbon dots contained in each carbon dot inclusion body is high, and the emission lifetime is also long. Therefore, the light emitter of the present invention can be applied to various uses such as a fluorescent probe and a material for a wavelength conversion layer of an illumination device.

FIGS. 1A to 1C are schematic views each showing a structure of a carbon dot inclusion body as a light emitter or a carbon dot inclusion body included in the light emitter according to an embodiment of the present invention. FIG. 2 is an image diagram of an embodiment of a fluorescent probe to which a carbon dot inclusion body included in a light emitter is applied. FIG. 3 is a schematic cross-sectional view of an embodiment of an LED device in which a carbon dot inclusion body included in a light emitter is applied to a wavelength conversion layer. 4A is a schematic diagram for explaining the configuration of the projection display device, and FIG. 4B is a projection display device in which the carbon dot inclusions included in the light emitter are applied to the light adjustment layer. It is a front view of one embodiment of the color wheel for use. FIGS. 5A to 5D are schematic cross-sectional views of an embodiment of a backlight device in which carbon dot inclusions included in a light emitter are applied to a wavelength conversion layer. FIG. 6 is a schematic cross-sectional view of an embodiment of a photoelectric conversion device in which a carbon dot inclusion body included in a light emitter is applied to a wavelength conversion layer.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the invention. In the present application, “˜” representing a numerical range is used in a sense including numerical values described before and after the numerical value as a lower limit value and an upper limit value.

1. Luminescent body The luminous body according to the embodiment of the present invention includes a carbon dot inclusion body in which one or a plurality of carbon dots having a variation value of a particle size of a certain value or less are covered with an insulator. In this specification, “the carbon dot is covered with an insulator” means that the carbon dot is included in the insulator in a state of being in close contact with the insulator, and the carbon dot inclusion body has a carbon dot on the surface thereof. Means substantially unexposed. “The carbon dots are not substantially exposed” means that the carbon dots are not exposed at all, or the exposure is suppressed to the extent that the outflow of excited electrons from the carbon dot surface is sufficiently suppressed. This means that the exposure of carbon dots is at most 30% or less, preferably 20% or less, more preferably 10% or less. The degree of exposure can be measured by a BET adsorption method or the like.

As described above, in a light-emitting body in which an insulator is stacked on a known graphene nanosheet, stress is easily applied to the edge portion of the graphene nanosheet when the insulator is stacked. Therefore, the insulator is easily peeled from the edge portion side. And the excitation electron flows out from the part which the insulator peeled, and there exists a subject that the quantum yield and light emission lifetime of a light-emitting body are hard to fully increase. Moreover, in the said light-emitting body (lamination | stacking body of a graphene sheet), it is difficult to equalize the size of the graphene sheet which each light-emitting body contains, and variation is easy to produce in the fluorescence intensity which each light-emitting body emits. In addition, since the size of the graphene sheet included in each light emitter varies, the chromaticity of the fluorescence emitted from each light emitter varies, and the peak of the obtained fluorescence spectrum tends to be broad. When such a light emitter is applied to, for example, a fluorescent probe, it is difficult to grasp the amount of the target substance based on the fluorescence intensity. In addition, the signal / noise ratio tends to be low, and high-precision measurement is difficult. On the other hand, when such a light emitter is used for a wavelength conversion layer or the like of a lighting device, chromaticity variation and luminance variation are likely to occur in the light emitting surface of the lighting device.

In addition, in the phosphor that contains carbon dots in the pores of the porous silica described in the above-mentioned non-patent document, the carbon dots are held in such a state that they are detached from the pores when vibration is applied. It is presumed that the carbon dot surface is exposed from the porous silica and is not in close contact with the porous silica in many regions. For this reason, excited electrons easily flow out from the carbon dot surface, and it is difficult to sufficiently increase the quantum yield and light emission lifetime of the light emitter.

On the other hand, in the carbon dot inclusion body included in the light emitter of the present embodiment, the carbon dots are covered with an insulator, and the outflow of excited electrons of the carbon dots is sufficiently suppressed. Therefore, according to the carbon dot inclusion body, a high quantum yield and a long emission lifetime can be obtained. Further, the carbon dots included in each carbon dot inclusion body have a small particle size variation, and there is little variation in the intensity and chromaticity of the fluorescence emitted by each carbon dot.

In addition, in the carbon dot inclusions included in the light emitter of the present embodiment, by controlling the number of carbon dots included in each carbon dot inclusion, the fluorescence intensity emitted by each carbon dot inclusion can be adjusted to the intended intensity. it can. Therefore, it becomes easy to make the fluorescence intensity of each carbon dot inclusion body uniform. For this reason, the light emitter of this embodiment can be used in a wide range of applications, and is particularly useful as a material for a fluorescent probe, a wavelength conversion layer of various lighting devices, and the like.

The carbon dot inclusion body may be in the form of particles or a bulk such as a sheet as described later. Further, the light emitter may be composed only of the carbon dot inclusions described above, or may contain other components such as a dispersion medium in addition to the carbon dot inclusions. That is, the light emitter of the present embodiment can take various embodiments such as powder, bulk, or slurry. Hereinafter, the carbon dot inclusion body will be described, and then other components that the light emitter may contain will be described.

(1) Carbon Dot Inclusion Body As described above, the carbon dot inclusion body included in the light emitter of the present embodiment includes carbon dots and an insulator that covers the carbon dots. A schematic diagram of the carbon dot inclusion is shown in FIG. The carbon dot inclusion body 3 may be a carbon dot single inclusion particle 3a in which only one carbon dot 1 is included in an insulator 2 as shown in FIG. When the carbon dot inclusion is the carbon dot single inclusion particle 3a, the carbon dot inclusion 3 has a core-shell structure in which the carbon dot is a core and the insulator is a shell. On the other hand, as shown in FIG. 1B, the carbon dot inclusion body is a carbon dot multiple inclusion body 3b in which a plurality (three in FIG. 1B) of carbon dots 1 are included in an insulator 2. There may be. In this case, the shape of the carbon dot inclusion body is not limited to a particle shape, and may be a bulk shape such as a sheet shape as shown in FIG.

-Carbon dot Carbon dot should just be the particle | grains mainly comprised from carbon, and is not restrict | limited in particular. The carbon dots may be, for example, fine particles made of graphene oxide (graphene oxide) in which carbon atoms are bonded by sp ² bonds and arranged in the same plane. Strictly speaking, graphite with a single layer structure should be defined as graphene, but in this specification, graphite with a multilayer structure is also included in the concept of graphene.

The carbon dots may be obtained by reducing graphene oxide fine particles. Examples of the reduction treatment of graphene oxide fine particles include heat treatment, light irradiation, treatment with a reducing agent, exposure to a reducing atmosphere, and the like. Further, the carbon dots may be those obtained by introducing a hydroxyl group, a carboxy group, or an epoxy group on the surface of the graphene oxide fine particles, or an acid anhydride that is a dehydrated body of two adjacent carboxy groups. In particular, when the carbon dot has a carboxy group on its surface, it becomes easy to chemically bond with an insulator described later, and the quantum yield is likely to increase. The method for introducing a hydroxyl group or a carboxy group is not particularly limited. For example, a desired functional group can be introduced by appropriately selecting a carbon compound for preparing a carbon dot. Further, the hydroxyl group, the carboxy group, the epoxy group, the acid anhydride group, and the like are preferably introduced in a range where the amount of oxygen contained in the carbon dot is 2 to 50% by mass with respect to the mass of the carbon dot. . The amount of oxygen with respect to the mass of the carbon dots is more preferably 2 to 47% by mass, and further preferably 5 to 47% by mass. If the carbon dot contains the above-mentioned range, hydroxyl group or carboxy group, these are likely to chemically bond at the interface between the insulator and graphene oxide fine particles (carbon dots) described later, and the quantum yield is likely to increase.

The oxygen content can be specified by XPS (X-ray photoelectron spectroscopy) or energy dispersive X-ray analysis combining SEM (scanning electron microscope) and TEM (transmission electron microscope). .

Further, the carbon dots may have both a graphene structure part having high crystallinity derived from graphite and an amorphous structure part. When the carbon dot includes an amorphous structure portion, the quantum yield is likely to be higher than that in the case where the light emitter is formed only of the graphene structure portion having high crystallinity. Carbon dots with high crystallinity have a graphene layer and a graphene layer laminated densely, and it is considered that the quantum yield is reduced due to a loss resulting from a new path of electron transfer between layers. The presence or absence of the amorphous structure portion can be determined from the presence or absence of lattice fringes in the image observed with a transmission microscope (hereinafter also referred to as “TEM”), the peak height of the Raman spectrum, and the like.

Here, the carbon dot of the present embodiment has a variation coefficient of particle size (hereinafter also referred to as “CV value”) of 20% or less, preferably 15% or less, and more preferably 10% or less. The CV value is a numerical value representing variation in statistics, and is represented by the following formula.
CV value [%] = (σ / D) × 100
In the above formula, σ represents a standard deviation, and D represents an average particle diameter of carbon dots. In this specification, the particle size of the carbon dots is a value obtained by image observation by TEM, and the standard deviation and average particle size are obtained when 100 particles randomly selected by image observation by TEM are observed. Value. In addition, when the carbon dots are not spherical, the “particle diameter” in the coefficient of variation of the particle diameter refers to the long diameter of the particles. The major axis of the particles can be determined by the method described later. Here, the smaller the CV value, the higher the uniformity of the particle size. When the CV value of the carbon dots is 20% or less, the intensity of the fluorescence emitted by each carbon dot is less varied, and its color Purity is also likely to increase.

The shape of the carbon dots is not particularly limited, but the ratio (b / a) of the major axis (b) to the minor axis (a) of the particles (hereinafter also referred to as “aspect ratio”) is 1.0 to 1.5. Preferably, it is in the range of 1.0 to 1.4, more preferably in the range of 1.0 to 1.3. When the aspect ratio is in the above range, when the insulator is formed around the carbon dots, the insulator is hardly distorted, and the insulator is difficult to peel off from the carbon dot surface.

The above aspect ratio can be measured as follows, but is not limited to this method. First, a dispersion liquid in which carbon dots are dispersed in a dispersion medium is prepared, and the dispersion liquid is dropped on a slide glass and dried. Thereby, a carbon dot can be fixed so that a Z-axis direction may become a short axis. Subsequently, an image is observed from the X-axis / Y-axis surfaces of the carbon dot particles by TEM to obtain the major diameter (b) of the carbon dots. And about this sample, a short axis (a) is calculated | required by observing using AFM (atomic force microscope). Then, from these values, the minor axis (a) / major axis (b) is calculated and used as the aspect ratio.

Here, the short diameter (a) and the long diameter (b) of the carbon dot are not particularly limited as long as the carbon dot is excited by light of a specific wavelength and emits fluorescence, but the long diameter ( b) is preferably from 0.5 to 30.0 nm, more preferably from 2.0 to 10.0 nm. On the other hand, the minor axis (a) is preferably 0.4 to 25.0 nm, and more preferably 1.0 to 10.0 nm.

-Insulator The type of insulator covering the carbon dots is not particularly limited as long as it can transmit the fluorescence emitted by the carbon dots and is made of a material having a higher band gap than the carbon dots. The insulator material may be, for example, an organic resin, an inorganic compound, or a composite material thereof. If the carbon dots are covered with an insulator having a band gap higher than that of the carbon dots, the excited electrons of the carbon dots hardly flow out to the outside, and the quantum yield can be increased. In general, when the fluorescent substance is at a high concentration, the molecules interact with each other and concentration quenching is likely to occur. However, in the carbon dot inclusion body included in the phosphor of this embodiment, the carbon dots are isolated from each other by an insulator. Therefore, the carbon dots do not interact with each other, and concentration quenching hardly occurs. Furthermore, it is possible to obtain an effect that particles are hardly aggregated by covering the carbon dots with an insulator.

Examples of insulator materials include epsilon caprolactam, acrylic acid polymer, cellulose resin, polyvinyl resin, polyurethane resin, acrylic resin, polyester resin, silicone resin, polyethylene glycol or polyethylene oxide, polyimide resin, polycarbonate resin, Polyamide resins, melamine resins, metalloxane compounds having a metalloxane skeleton, and the like are included. Only one of these may be included in the insulator, or two or more thereof may be included. These may be combined.

Here, the insulator material preferably has a group capable of bonding with a functional group on the surface of the carbon dot. If the functional group present on the surface of the carbon dot is freely movable, when the carbon dot is excited, the excitation energy is easily converted into rotational energy or vibration energy, and energy loss is likely to occur. That is, the quantum yield tends to decrease. On the other hand, if they are chemically bonded at the interface between the insulator and the carbon dots, energy loss is unlikely to occur, and a high quantum yield is easily obtained.

Examples of materials that can be chemically bonded to the functional group on the carbon dot surface include materials having a hydroxyl group, a mercapto group, or an amino group. Hydroxyl groups and mercapto groups react with carboxy groups present on the surface of carbon dots to form ester bonds. The amino group reacts with a carboxy group present on the carbon dot surface to form an amide bond. The amino group reacts with an acid anhydride group which is a dehydrated carboxy group present on the surface of the carbon dot to form an imide bond. The quantum yield is particularly likely to increase when an amide bond or an imide bond is included at the interface between the insulator and the carbon dots. Therefore, it is preferable that the insulator contains a compound having an amino group in its structure, such as a melamine resin or a cured product of an amino group-containing silane coupling agent.

It is also preferable that the insulator contains a metalloxane compound. When a metalloxane bond is included in the component constituting the insulator, the strength of the insulator is easily increased, and the wet heat resistance of the carbon dot inclusion body is easily increased. In addition, since the metalloxane bond is rigid, a functional group that becomes the emission center of the carbon dot can be immobilized. As a result, energy loss due to rotation and vibration of the functional group serving as the emission center is suppressed, and the quantum yield is improved. In addition, a metalloxane type compound will not be restrict | limited especially if it has a metalloxane bond, For example, it can be set as the hardened | cured material of various metal alkoxides. Further, the type of metal contained in the metalloxane bond is not particularly limited, but Si, Al, Zn, Ti, and Zr are preferable from the viewpoints of light transmittance, strength, wet heat resistance, and the like of the insulator.

The amount of the insulator included in the carbon dot inclusion body is not particularly limited as long as it can be included so that the carbon dots are not substantially exposed. For example, in the carbon dot single inclusion particle in which the insulator contains only one carbon dot, the mass of the insulator is preferably 10 to 100,000 parts by mass with respect to the mass of the carbon dots (100 parts by mass). More preferably, it is ˜10,000 parts by mass. On the other hand, in the case of a plurality of carbon dot inclusions including a plurality of carbon dots, the mass of the insulator is 20 to 200,000 parts by mass with respect to the total amount (100 parts by mass) of carbon dots contained in each of the carbon dot inclusions. It is preferably 100 to 20000 parts by mass. When the amount of the insulator in the carbon dot inclusion is equal to or more than the lower limit value, the carbon dots are difficult to be exposed on the surface of the carbon dot inclusion. On the other hand, when the amount of the insulator is less than or equal to the upper limit value, the light transmittance and the like of the insulator are improved, and the fluorescence emitted by the carbon dots is easily taken out of the carbon dot inclusion body.

-Shape of carbon dot inclusion body The shape of the carbon dot inclusion body is appropriately selected according to its use and the number of carbon dots included in the carbon dot inclusion body.

The shape of the carbon dot-inclusive particles in which only one carbon dot is covered with an insulator is not particularly limited, but is preferably substantially spherical. The average particle size of the carbon dot-containing particles is preferably 1 to 100 nm, and more preferably 2 to 50 nm. When the average particle diameter of the carbon dot single inclusion particles is within the above range, the carbon dot single inclusion particles can be easily applied to various uses such as a fluorescent probe. The method for measuring the average particle size of the carbon dot-inclusive particles can be the same as the method for measuring the average particle size of the carbon dots described above.

Also, in the carbon dot single inclusion particles, it is preferable that there is little variation in the particle size, and the CV value is preferably 30% or less, and more preferably 20% or less. The calculation method of the CV value of the carbon dot single inclusion particle may be the same as the calculation method of the CV value of the carbon dot described above.

On the other hand, the shape of the carbon dot inclusion body in which a plurality of carbon dots are covered with an insulator is not particularly limited. The carbon dot multiple inclusion body may be in the form of particles, for example, but may be in the form of a bulk such as a sheet. When the carbon dot multiple inclusions are in the form of particles, each carbon dot multiple inclusion preferably includes 2 to 100 carbon dots, more preferably 5 to 80 carbon dots, and preferably 10 to 50 carbon dots. Further preferred. When the number of carbon dots contained in a plurality of carbon dot inclusions is within the above range, the particle size can be sufficiently reduced, and the carbon dot inclusions can be easily applied to various applications. The number of carbon dots included in each carbon dot multiple inclusion body may vary, but is preferably substantially uniform. Thereby, the fluorescence intensity which each carbon dot multiple inclusion body emits can be arrange | equalized, and it becomes possible to apply a light-emitting body (carbon dot inclusion body) to various uses.

In addition, when the carbon dot multiple inclusion body is in the form of particles, the shape is not particularly limited, but is preferably substantially spherical. At this time, the average particle diameter of the carbon dot multiple inclusions is preferably 2 to 500 nm, and more preferably 10 to 100 nm. When the average particle diameter of the carbon dot multiple inclusions is within the above range, these can be easily applied to various uses such as a fluorescent probe. The measuring method of the average particle diameter of the carbon dot multiple inclusion body can be the same as the measuring method of the average particle diameter of the carbon dots described above.

Further, when the carbon dot multiple inclusion body is in the form of particles, it is preferable that the variation in the particle diameter is small, and the CV value is preferably 40% or less, and preferably 30% or less. The calculation method of the CV value of the carbon dot multiple inclusion body may be the same as the calculation method of the CV value of the carbon dots described above.

On the other hand, when the carbon dot plural inclusions are in a bulk shape such as a sheet shape, the number of carbon dots included in the carbon dot plural inclusions is appropriately selected according to the size, thickness, and shape of the carbon dot plural inclusions. Moreover, the shape of the carbon dot multiple inclusion body is also appropriately selected according to the application.

(2) Others The light emitter may contain components other than carbon dot inclusions as necessary. Examples of other components include a dispersion medium. When the luminous body is a slurry in which carbon dot inclusions are dispersed in a dispersion medium, the carbon dot inclusions can be easily applied to various substrates.

The dispersion medium for dispersing the carbon dot inclusion body is not particularly limited as long as it is a solvent capable of sufficiently dispersing the carbon dot inclusion body. The dispersion medium is not particularly limited as long as it is compatible with the insulator on the surface of the carbon dot inclusion body and can be uniformly dispersed. For example, water, high polarity solvent, amphiphilic solvent, low polarity It can be a solvent. The amount is appropriately selected according to the use of the light emitter.

2. Manufacturing method of luminous body The above-described luminous body can be manufactured by performing a process of preparing carbon dots and a process of covering the carbon dots with an insulator. The manufacturing method of a light-emitting body may include other steps as necessary.

(1) Carbon dot preparation process In the manufacturing method of a light-emitting body, first, carbon dots having a CV value of 20% or less are prepared. The method for preparing carbon dots having a CV value of 20% or less is not particularly limited. For example, carbon dots may be prepared by a known method and classified to make the CV value 20% or less. Alternatively, carbon dots having a uniform particle size may be prepared by a hot injection method or a carbon dot synthesis method using a template. Among these, a carbon dot synthesis method using a template is particularly preferable from the viewpoint that carbon dots having a uniform particle size are easily obtained and that production efficiency is high. Hereinafter, although an example of the carbon dot synthesis method using a template is shown, the preparation method of a carbon dot is not restricted to the method concerned.

In the carbon dot synthesis method using a template, first, a template having a uniform pore system is prepared. The material of the mold is not particularly limited, but is preferably a mold made of mesoporous silica or zeolite from the viewpoint of heat resistance and the like. In particular, a mold made of mesoporous silica, which is porous silica having nano-sized pores, is preferable from the viewpoint that the pore size can be controlled. A template made of sub-nano-sized porous silica shown in Non-Patent Document 1 may be used.

A mold made of mesoporous silica can be produced as follows. First, a surfactant, a silica source such as tetraethoxysilane (hereinafter also referred to as “TEOS”), and an acid or base catalyst are mixed. Then, the silica source is subjected to a sol-gel reaction in a state where the surfactant forms micelles, that is, in a state where the silica source is adsorbed around the surfactant. Next, by firing this, the surfactant is thermally decomposed to obtain mesoporous silica having uniform pores. The pore diameter of mesoporous silica can be easily controlled by changing the alkyl chain length of the surfactant.

Further, mesoporous silica can also be prepared by a method described in, for example, International Publication No. 2011/108649. Further, commercially available mesoporous silica may be applied. Examples of commercially available mesoporous silica include meso pure series manufactured by Mitsubishi Chemical and reagent grade mesoporous silica manufactured by Sigma-Aldrich.

Carbon dots are obtained by filling the mold with a carbon compound and sintering the carbon compound in this state. The carbon compound is not particularly limited as long as it can be introduced into the pores of the mesoporous silica and is carbonized by sintering to become carbon dots. Examples of such carbon compounds include carboxylic acids such as citric acid, tartaric acid, oxalic acid and melitonic acid; monosaccharides such as glucose, fructose and mannose; polysaccharides such as glycogen, dextrin and cellulose; lysine, leucine and methionine. Amino acids; resins such as acrylic resins, epoxy resins, polycarbonate resins; and the like. Among these, the carbon compound is preferably a carboxylic acid, and particularly preferably citric acid, from the viewpoint of appropriately containing oxygen in the molecule and having a carboxy group.

Further, the method for introducing the carbon compound into the above-described template (mesoporous silica pores) is not particularly limited. When the carbon compound is in a solid state, a method can be used in which the template is immersed in an aqueous solution in which the carbon compound is dispersed in water. Further, when the carbon compound is in a liquid state, a method can be used in which the template is immersed in the carbon compound or an aqueous solution of the carbon hydrogen compound. Furthermore, when the carbon compound is in a gaseous state, a method can be used in which the template is allowed to stand in an atmosphere containing the raw material carbon compound and the carbon compound is allowed to enter the template. Among these methods, a method of immersing the template in an aqueous solution of a solid or liquid carbon compound is particularly preferable. According to the said method, the particle size distribution of the carbon dot obtained can be adjusted with the density | concentration of the carbon compound in aqueous solution. For example, when the concentration of the carbon compound is reduced, carbon dots having a small CV value are easily obtained.

In addition, after introducing the carbon compound into the mold, before the carbon compound is sintered, excess carbon compound attached to the mold surface may be removed. Examples of the method for removing excess carbon compounds include a method of washing the template with a lower aliphatic alcohol such as ethanol or methanol.

After that, by sintering the carbon compound inside the mold, the carbon compound is carbonized to form carbon dots. The temperature and time during sintering are appropriately selected according to the type and amount of the carbon compound. The sintering temperature is usually preferably 200 ° C. or higher, more preferably 200 to 500 ° C., and further preferably 250 to 400 ° C. Further, during sintering (carbonization), the temperature is raised from room temperature to a predetermined sintering temperature, and the temperature is maintained for a certain period of time. It is possible to adjust the ratio. Specifically, the aspect ratio can be reduced by decreasing (slowing) the rate of temperature increase during temperature increase.

In addition, the sintering (carbonization) time is usually preferably about 0.5 to 20 hours, more preferably 2 to 5 hours. The atmosphere at the time of sintering is particularly preferably an air atmosphere containing oxygen atoms. However, the atmosphere is not particularly limited as long as it is an atmosphere partially containing oxygen, and oxygen gas is added to an atmosphere of nitrogen gas or rare gas. The introduced atmosphere may be used.

Then, the carbon dots sintered in the mold are taken out from the mold by applying vibration by ultrasonic treatment or the like. Then, you may classify the carbon dot taken out from the casting_mold | template as needed.

(2) Carbon dot coating step with an insulator The carbon dot obtained in the above step is coated with an insulator. The method for coating the carbon dots with the insulator is not particularly limited, and is appropriately selected according to the type of the insulator and the shape of the desired carbon dot inclusion body.

In the case of granular carbon dot inclusions, (i) carbon dots are placed in the pores of a porous bead made of an insulator (inorganic material or organic resin). And then sealing the pores of the porous bead with the same material as the porous bead, (ii) adding carbon dots to the precursor of the insulator, and then adding the carbon dots to the precursor of the insulator And (iii) a method of preparing carbon dots using a mold made of an insulator and filling the pores of the mold with the same material as the mold. . In addition, (iv) a method in which resin beads having pores in the interior are swollen and carbon dots are taken in, or (v) a method in which alternate adsorption of polyions is used to adsorb carbon dots can be applied. .

Among these, the method (ii) or (iii) is preferable from the viewpoint that the number of carbon dots in the insulator can be easily controlled, and that the carbon dots can be easily covered completely. In particular, according to the method (ii), the particle size of the carbon dot inclusion body can be easily adjusted.

When the carbon dot inclusion body is obtained by the method (i), the porous beads and the carbon dots made of an insulator (inorganic material or organic resin) are stirred in a solvent, etc., in the pores of the porous beads. Carbon dots can be placed. Further, the number of carbon dots arranged in each porous bead is adjusted by the number of pores of the porous bead. Then, by filling the pores of the porous beads with an inorganic material or organic resin that constitutes the porous beads, or a precursor thereof, the carbon dots are coated with an insulator by curing the filler. An inclusion body is obtained.

The method of filling the porous beads with an inorganic material, an organic resin, or a precursor thereof is not particularly limited, and may be injected with a syringe or the like. Alternatively, the porous beads may be dispersed in a solution containing an inorganic material, an organic resin, or a precursor thereof, and filled in the pores of the porous beads. The method for curing the porous material after filling the pores of the porous beads with an inorganic material or an organic resin, or a precursor thereof is appropriately selected according to the type of the inorganic material, the organic resin, or the precursor, One example is heating.

When obtaining carbon dot inclusions by the method (ii), an insulator precursor (inorganic material or organic resin precursor) and carbon dots are mixed and a shearing force is applied. Thereby, a carbon dot can be coat | covered with the precursor of an insulator. In addition, you may add a solvent as needed. The method for applying the shearing force is not particularly limited, and may be, for example, a stirring process, an ultrasonic process, a process using a bead mill, a process repeatedly passing through a narrow channel, a process using a rotating disk, or the like. And the carbon dot inclusion body by which the carbon dot was coat | covered with the insulator is obtained by hardening the precursor of an insulator. The method for curing the insulator precursor is appropriately selected according to the type of the insulator precursor, and heating is an example.

The functional group of the insulator precursor and the functional group on the surface of the carbon dot may be chemically reacted simultaneously with the coating of the carbon dots with the insulator precursor. Thereby, the carbon dot inclusion body in which these are chemically bonded at the interface between the carbon dots and the insulator is obtained. Such a chemical reaction can be performed by the method described in JP-A-2015-108572.

When carbon dot inclusions are obtained by the method (iii), carbon dots are produced in a mold such as mesoporous silica as described in the carbon dot preparation method. And the inorganic material which comprises a casting_mold | template, or its precursor is filled into the pore of the said casting_mold | template, and this is hardened. Thereby, the carbon dot inclusion body by which the carbon dot was coat | covered with the insulator is obtained. The method for filling the inorganic material constituting the template or its precursor into the pores of the template is not particularly limited, and can be the same method as in the above (i). Further, in the method of closing the pores of the template, the template itself may be heated and melted if the fluorescence characteristics of the carbon dots do not deteriorate.

When obtaining carbon dot inclusions by the method (iv), prepare resin beads having pores inside. The method for preparing the resin beads is not particularly limited and may be a known method. And it can be set as the method of making the said resin bead swell by heating, moistening, etc., and taking in a carbon dot.

When carbon dot inclusions are obtained by the method (v), for example, when carbon dots having a polar group such as a carboxy group on the surface are dispersed in water, they are negatively charged. On the other hand, an insulator having a positively chargeable polar group is dispersed in a solvent and positively charged. When these are mixed, the insulator is adsorbed around the carbon dots, so that a carbon dot inclusion body in which the carbon dots are included in the insulator is obtained. The combination of the carbon dots and the insulator is not particularly limited as long as it is a combination of positive and negative at the time of charging. A carbon dot that is positively charged and a negatively charged insulator may be used. .

On the other hand, when the carbon dot inclusion body is made into a bulk shape, the carbon dot inclusion body can be produced by the same method as in the above (ii).

(3) Other In addition, the manufacturing method of the light-emitting body mentioned above is a process which dries the carbon dot inclusion body obtained by the said process as needed, a carbon dot inclusion body, and a solvent, And the like.

3. Use of luminous body In the carbon dot inclusion body included in the luminous body of the present embodiment, the quantum yield of carbon dots is very high. Further, the intensity of the fluorescence emitted by each carbon dot is uniform. Furthermore, the chromaticity of the fluorescence emitted by each carbon dot has little variation and the light emission life is long. Therefore, the light emitter of the present embodiment can be applied to various uses.

Hereinafter, the case where the carbon dot inclusions contained in the luminescent material are used as materials for fluorescent probes, LED devices, projection display wheels, backlight devices, and photoelectric conversion devices will be described. Applications of the luminescent material of the present invention Is not limited to these.

(1) Fluorescent Probe In the present embodiment, the carbon dot inclusion body included in the above-described luminescent material is applied to a fluorescent probe for fluorescently labeling a target biomolecule. As shown in the image diagram of FIG. 2, the fluorescent probe 4 has an antibody for specifically binding to a target biomolecule (antigen) 5 and a carbon dot inclusion body 3 bound to the antibody. Can do.

When a fluorescent probe is administered to a living cell or biological tissue having a target biomolecule, the fluorescent probe specifically binds to or specifically adsorbs to the target biomolecule. Then, when excitation light (radiation) having a predetermined wavelength is irradiated to the position where the fluorescent probe is administered, the carbon dots included in the fluorescent probe are excited to emit fluorescence having a predetermined wavelength. Therefore, by detecting the fluorescence, it is possible to detect the position of the target biomolecule and grasp the detection amount. In particular, by controlling the number of carbon dots contained in each carbon dot inclusion and adjusting the fluorescence intensity emitted by each carbon dot inclusion to the intended intensity, the fluorescence intensity of each carbon dot inclusion can be made uniform. Thus, the accuracy of quantitative measurement can be improved.

Such a fluorescent probe can be obtained by covalently bonding (for example, an amide bond) a functional group on the surface of the carbon dot inclusion body and a functional group of the target-directing molecule (antibody). A targeting molecule is a molecule having a function of specifically binding to a specific tissue or cell. The kind of target-directed molecule is not particularly limited, and is appropriately selected according to the target substance. Examples of targeting molecules include the following:

(I) When the target is various marker proteins or peptides that are specifically expressed in diseased tissues or cells such as cancer, the target-directed molecule is an antibody against them (for example, HER2 antibody, cancer-specific antibody, blood vessel Endothelial cell-specific antibody, tissue-specific antibody, phosphorylated protein antibody, etc.) or an affinity substance thereof, folic acid, transferrin, transferrin-binding peptide and the like.
(Ii) When the target is a sugar chain, the target-directing molecule can be a protein (for example, lectin) having binding properties with the sugar chain.
(Iii) Other target-directing molecules include, for example, cell membrane affinity substances, viral cell recognition sites, lipophilic tracers, virus particles having no replication function, and organelle affinity substances (eg, DNA, mitochondria, cytoskeleton) Molecule, Golgi apparatus, lysosome, endosome, autophagosome, etc.).

As described above, in the illuminant used in this embodiment, the fluorescence intensity of the carbon dots included in each carbon dot inclusion body is uniform, and the color purity thereof is high. Therefore, the amount of target biomolecules can be accurately determined by using, for example, carbon dot single inclusion particles containing only one carbon dot, or multiple inclusions of carbon dots in which the number of carbon dots contained is evenly arranged in a fluorescent probe. It becomes possible to measure. Moreover, since the color purity of the fluorescence emitted from the carbon dots is high, the signal / noise ratio when the fluorescence spectrum is measured can be sufficiently increased. Therefore, it is possible to specify the position and amount of the target biomolecule with high accuracy.

(2) LED device This embodiment is an LED device using the carbon dot inclusions included in the above-described light emitter as a material for forming the wavelength conversion layer of the LED device. A schematic cross-sectional view of the LED device of the present embodiment is shown in FIG. The LED device 50 includes a substrate 10, an LED element 20 disposed on the substrate 10, and a wavelength conversion layer 30 that covers the LED element 20. In the LED device 50, a part of light emitted from the LED element 20 is converted into light having a specific wavelength by the wavelength conversion layer 30, so that the color of light emitted from the LED device 50 is set to a desired color. For example, when the LED element 20 emits blue light (light of about 420 nm to 485 nm), the wavelength conversion layer 30 includes a carbon dot inclusion body that emits yellow fluorescence when excited by the blue light, thereby transmitting the wavelength conversion layer 30. The resulting light is white.

The wavelength of the light emitted from the LED element 20 is not particularly limited as long as it is a wavelength that can excite the carbon dots, and can be blue light, near ultraviolet light, or the like. Further, the color of the fluorescence emitted by the carbon dots is not particularly limited, and may be any color such as red, green, blue, and yellow. The combination of the color of light emitted from the LED element 20 and the color of fluorescence emitted from the carbon dots is appropriately selected according to the use of the LED device 50 and the like. Further, the wavelength conversion layer 30 may include only one type of carbon dot inclusion body, or may include two or more types.

Here, the wavelength conversion layer 30 can be a layer in which carbon dot inclusions are bound by a binder. The binder is not particularly limited as long as it has light transmittance and can sufficiently bind the carbon dot inclusion body, and may be made of an inorganic material or a resin. Good. The binder can be a transparent resin such as an epoxy resin or a silicone resin, or a translucent ceramic such as polysiloxane.

Such a wavelength conversion layer 30 can be obtained by applying the above-described phosphor and a composition containing the binder or its precursor by a known method and curing the composition. The composition for forming the wavelength conversion layer 30 may contain a solvent as necessary. In addition, for the formation of the wavelength conversion layer 30, it is preferable to apply a light emitting body in the form of powder or slurry. By using a powder-like or slurry-like illuminant, the carbon dot inclusions can be uniformly dispersed in the wavelength conversion layer 30.

As described above, in the illuminant used in this embodiment, the intensity and chromaticity of the fluorescence emitted by each carbon dot can be made uniform. Accordingly, by including such carbon dot single inclusion particles containing only one carbon dot or a plurality of carbon dot inclusion bodies in which the number of carbon dots contained is evenly arranged in the wavelength conversion layer, the light is emitted from the LED device. Light color and brightness are likely to be uniform. In addition, since the color purity of the fluorescence emitted by each carbon dot is high, the effect that the chromaticity of the light emitted from the LED device easily falls within a desired range is also obtained.

(3) Color wheel for projection display device In this embodiment, the carbon dot inclusions included in the above-described light emitter are used for the light adjustment layer of a color wheel for projection display device (hereinafter also referred to as “color wheel”). Used as a material. A schematic diagram of a projection display device incorporating a color wheel is shown in FIG. The projection display device 120 includes at least a light source 110, a color wheel 100, and a projection optical system 114. The light emitted from the light source 110 is collected by the lens 111 and the like, and is applied to the color wheel 100 described above. At this time, light from the light source is diffused or wavelength-converted by a light adjustment layer (not shown) of the color wheel 100. The light transmitted through the color wheel 100 is guided to the projection optical system 114 via the lens 112, the mirror 113, and the like, and is projected by the projection optical system 114 to display an image on the screen. The carbon dot inclusions included in the above-described light emitter are materials for color wheels of such a projection display device, more specifically, as materials for converting light from the light source 110 into light of other wavelengths. Can be included in the color wheel.

As shown in FIG. 4B, the color wheel 100 of the projection display device has a structure in which a substrate 101 and a light adjustment layer 102 including a carbon dot inclusion body are laminated. The color wheel 100 is installed between the light source 110 and the projection optical system 114 in the projection display device, and diffuses the light from the light source 110 or converts the light from the light source 110 into light of another specific wavelength. It performs the function to do.

Although only one type of light adjustment layer may be formed on the color wheel 100, a plurality of types of light adjustment layers 102a to 102c are formed on one color wheel 100 as shown in FIG. 4B. May be. For example, when the light from the light source of the projection display device is ultraviolet light, the light adjustment layer 102a including the carbon dot inclusion that emits blue light by receiving the ultraviolet light, and emits green light by receiving the ultraviolet light. By using a color wheel 100 or the like that includes a light adjustment layer 102b that includes carbon dot inclusions and a light adjustment layer 102c that includes carbon dot inclusions that receive ultraviolet light and emit red light, the light source is only one type. Even so, the three primary colors of light can be reproduced. Note that the type of the light adjustment layer 102 included in the color wheel 100, the region where the light adjustment layer 102 is formed, and the like, the type of the projection display device 120, the wavelength of light emitted from the light source 110, and the projection display device. It is appropriately selected according to the structure and the like.

Here, the light adjustment layer 102 may be a layer in which carbon dot inclusions are bound by a binder. The binder included in the light adjustment layer 102 can be the same as the binder included in the wavelength conversion layer of the LED device described above. Moreover, the formation method of the light adjustment layer 102 can also be made to be the same as the formation method of the wavelength conversion layer of the LED device. Note that it is preferable to apply a light-emitting body in the form of powder or slurry to the formation of the light adjustment layer 102. By using a light emitting body in the form of powder or slurry, the carbon dot inclusions can be uniformly dispersed in the light adjustment layer 102.

As described above, in the illuminant used in this embodiment, the intensity and chromaticity of the fluorescence emitted by each carbon dot can be made uniform. Therefore, by including such a carbon dot single inclusion particle containing only one carbon dot or a plurality of carbon dot inclusion bodies in which the number of carbon dots contained is evenly arranged in the light adjustment layer, the projection display device can The brightness of the emitted light is likely to be uniform, and color unevenness is less likely to occur. Moreover, since the color purity of the fluorescence emitted from each carbon dot is high, the color reproducibility of the image projected from the projection display device is good.

In the above description, the case where the color wheel is a transmissive color wheel has been described as an example. However, the carbon dot inclusion body included in the light emitter described above can also be applied to the reflective color wheel.

(4) Backlight Device In this embodiment, the carbon dot inclusions included in the above-described light emitter are used in a backlight device mounted on various displays and the like, specifically, the wavelength of the backlight device. It is also used as a material for the conversion layer. Examples of the backlight device of this embodiment are shown in FIGS. The backlight device 200 is a planar light emitting device provided on the back surface of a liquid crystal panel (not shown), for example, and irradiates the liquid crystal panel with light. The carbon dot inclusions included in the above-described light emitter are for converting a part of light from the light source 202 into light of other wavelengths, more specifically, a material for the wavelength conversion layer of such a backlight device. It can be applied to any material. In the backlight device 200, the light emitted from the light source 202 is converted by the wavelength conversion layer 201, so that light of a desired color can be irradiated onto the liquid crystal panel.

The configuration of the backlight device 200 is appropriately selected according to its use. For example, as illustrated in FIG. 5A, a configuration including a light source 202 and a wavelength conversion layer 201 disposed on the side of the light source 202 can be employed. Further, for example, as shown in FIG. 5B and FIG. 5C, a light guide 203 for diffusing light emitted from the light source 202 or light converted in wavelength by the wavelength conversion layer 201 is provided. It can also be configured. In this case, light emitted from the light source 202 or the wavelength conversion layer 201 is diffused by the light guide 203. Further, as shown in FIG. 5D, the light source 202 (202a, 202b, 202c) and the wavelength conversion layer 201 may be arranged with a gap therebetween.

Here, the wavelength conversion layer 201 can be a layer in which carbon dot inclusions are bound by a binder. The binder is not particularly limited as long as it has optical transparency and can sufficiently bind the carbon dot inclusion body. Such a binder can be the same as the binder included in the wavelength conversion layer of the LED device described above. Further, the method for forming the wavelength conversion layer 201 of the backlight device 200 can be the same as the method for forming the wavelength conversion layer of the LED device. In forming the wavelength conversion layer 201 of the backlight device 200, it is preferable to apply a powder or slurry-like light emitter. By using a powder-like or slurry-like illuminant, carbon dot inclusions can be uniformly dispersed in the wavelength conversion layer 201.

Moreover, in the light emitter of the present embodiment, the intensity and chromaticity of the fluorescence emitted by each carbon dot can be made uniform. Therefore, by including such carbon dot single inclusion particles containing only one carbon dot or a plurality of carbon dot inclusions with a uniform number of carbon dots contained in the wavelength conversion layer, the light is emitted from the backlight device. The color and brightness of the light is likely to be uniform. Moreover, since the color purity of the fluorescence emitted from each carbon dot is high, the effect that the chromaticity of the light emitted from the backlight device easily falls within a desired range is also obtained.

(5) Photoelectric Conversion Device This embodiment is a photoelectric conversion device using the carbon dot inclusion body included in the above-described light emitter in the wavelength conversion layer of the photoelectric conversion layer. FIG. 6 illustrates an example of a photoelectric conversion device. The photoelectric conversion device 300 has a structure in which an electrode layer 302, a P-type semiconductor layer 303, an N-type semiconductor layer 304, a transparent electrode layer 305, and a wavelength conversion layer 310 are stacked on a substrate 301. The light emitter (carbon dot inclusion body) can be used as a material for forming the wavelength conversion layer 310. More specifically, a material for converting light entering the photoelectric conversion layer into light having a desired wavelength can be used.

In a general photoelectric conversion device, only light of a specific wavelength contained in sunlight can be used for photoelectric conversion. Therefore, by including a carbon dot inclusion body in the wavelength conversion layer 310 of the photoelectric conversion device 300, the power generation efficiency of the photoelectric conversion device 300 can be improved. For example, fluorescence is obtained by exciting carbon dots in the carbon dot inclusion body with light having a wavelength not used for photoelectric conversion. As a result, the amount of light having a wavelength that can be used for photoelectric conversion increases, and the power generation efficiency of the photoelectric conversion device 300 is likely to increase.

Here, the wavelength conversion layer 310 included in the photoelectric conversion device 300 can be a layer in which carbon dot inclusions are bound by a binder. The binder is not particularly limited as long as it has optical transparency and can sufficiently bind the carbon dot inclusion body. Such a binder can be the same as the binder included in the wavelength conversion layer of the LED device described above. Moreover, the formation method of the wavelength conversion layer 310 of the photoelectric conversion apparatus 300 can also be made to be the same as the formation method of the wavelength conversion layer of the LED device. Note that it is preferable to apply a light emitting body in the form of powder or slurry in the formation of the wavelength conversion layer 310 of the photoelectric conversion device 300. By using a powder-form or slurry-form illuminant, the carbon dot inclusions can be uniformly dispersed in the wavelength conversion layer 310.

Hereinafter, specific examples of the present invention will be described. However, the scope of the present invention is not limited by this. In addition, although the display of "part" is used in an Example, unless otherwise indicated, "part by mass" is represented.

1. Production of mesoporous silica Mesoporous silica as a template was produced by the following method. Further, the pore diameter of mesoporous silica was measured as follows.

(Method for evaluating the pore size of mesoporous silica)
First, the pore size distribution of mesoporous silica was derived by the BET adsorption method using the phenomenon that the pressure changes according to the pore size when the nitrogen gas adsorbed in the pores is condensed. The peak value of the pore size distribution at this time was defined as the pore size. BELSORP-MR6 (manufactured by Microtrack Bell) was used for BET adsorption measurement.

(1) Production of C8 mesoporous silica Tetraethoxysilane (TEOS), hydrochloric acid aqueous solution (pH 1.0), and n-octyltrimethylammonium bromide were mixed at a molar ratio of 1: 5: 1, and the mixture was stirred at 60 ° C. for 24 hours. The gel was obtained by standing. The obtained gel was isolated, dried at 60 ° C. for 24 hours, and then sintered at 600 ° C. for 3 hours to obtain mesoporous silica having a pore diameter of about 1.2 nm. In the present specification, the numerical value corresponding to “n” of “Cn mesoporous silica” represents the chain length of the hydrocarbon group of the surfactant used in producing the template silica, and the pore size of the template It becomes an index of size.

(2) Production of C12 mesoporous silica Mesoporous silica was produced in the same manner as (1) C8 mesoporous silica except that dodecyltrimethylammonium bromide was used instead of n-octyltrimethylammonium bromide. The pore diameter of the obtained mesoporous silica was about 2.0 nm.

(3) Production of C16 mesoporous silica Mesoporous silica was produced in the same manner as (1) C8 mesoporous silica except that hexadecyltrimethylammonium bromide was used instead of n-octyltrimethylammonium bromide. The pore diameter of the obtained mesoporous silica was about 2.8 nm.

(4) Production of C18 mesoporous silica Mesoporous silica was produced in the same manner as (1) C8 mesoporous silica except that octadecyltrimethylammonium chloride was used instead of octyltrimethylammonium chloride. The pore diameter of the obtained mesoporous silica was about 3.2 nm.

2. Preparation of carbon dot dispersion A carbon dot dispersion was prepared by the following method. In addition, the CV value, average particle diameter, and aspect ratio (minor axis / major axis ratio) of the obtained carbon dots were confirmed by the following method.

(Particle size and CV value)
The average particle size of the carbon dots was confirmed by a TEM image (JEM-2100 Plus manufactured by JEOL) and calculated based on the particle size (major axis) of 100 randomly selected carbon dots. Moreover, the standard deviation was calculated | required from these particle size data, and CV value was computed from the following formula | equation.
CV value [%] = (σ / D) × 100
In the above formula, σ represents a standard deviation, and D represents an average particle diameter.

(How to check the aspect ratio of carbon dots)
The carbon dot dispersion liquid was dropped on a slide glass and dried to fix the carbon dots so that the Z-axis direction had a short diameter. Subsequently, an image was observed from the X-axis / Y-axis surfaces of the carbon dot particles using TEM (JEM-2500SE, manufactured by JEOL), and the major axis was obtained. Subsequently, the short diameter of the carbon dots was determined using AFM (Dimension Icon, manufactured by BRUKER) of the same sample. The aspect ratio of the carbon dots was determined from the ratio of the major axis and the minor axis. Here, the same measurement was performed 10 times for the samples of each example and comparative example, and the maximum value and the minimum value of the aspect ratio were confirmed.

(1) Preparation of carbon dot dispersion liquid 1 (carbon dot dispersion liquid having a particle diameter of 1.8 nm) by a template method 10 g of the above-mentioned C12 mesoporous silica was immersed in 1M citric acid aqueous solution and left for 24 hours. Subsequently, using a Kiriyama glass filter, excess citric acid aqueous solution was removed to obtain C12 mesoporous silica in which the citric acid aqueous solution was soaked in the pores. Then, C12 mesoporous silica impregnated with an aqueous citric acid solution was sintered at 400 ° C. for 3 hours to produce carbon dots in the pores of mesoporous silica. Subsequently, 10 mL of ethanol (EtOH) was added to mesoporous silica encapsulating carbon dots and subjected to ultrasonic treatment for 1 hour, so that the CV value was 15%, the particle size was 1.8 nm, and the aspect ratio was 1.0 to 1.4. A carbon dot dispersion liquid 1 in which a certain carbon dot was dispersed in EtOH was obtained.

(2) Preparation of carbon dot dispersion 2 (carbon dot dispersion having a particle size of 1.0 nm) by a template method Except that C8 mesoporous silica was used instead of C12 mesoporous silica, the same as the preparation of carbon dot dispersion 1 A carbon dot dispersion was prepared to obtain a carbon dot dispersion 2 in which carbon dots having a CV value of 10%, a particle size of 1.0 nm, and an aspect ratio of 1.0 to 1.3 were dispersed in EtOH.

(3) Preparation of carbon dot dispersion liquid 3 (carbon dot dispersion liquid having a particle size of 2.6 nm) by a template method Except for using C16 mesoporous silica instead of C12 mesoporous silica, the same as the preparation of carbon dot dispersion liquid 1 A carbon dot dispersion was prepared to obtain a carbon dot dispersion 3 in which carbon dots having a CV value of 20%, a particle size of 2.6 nm, and an aspect ratio of 1.0 to 1.5 were dispersed in EtOH.

(4) Preparation of carbon dot dispersion liquid 4 (carbon dot dispersion liquid having a particle size of 3.0 nm) by a template method Except that C18 mesoporous silica was used instead of C12 mesoporous silica, the same as the preparation of carbon dot dispersion liquid 1 A carbon dot dispersion was prepared to obtain a carbon dot dispersion 4 in which carbon dots having a CV value of 25%, a particle size of 3.0 nm, and an aspect ratio of 1.0 to 1.6 were dispersed in EtOH.

3. Preparation of Carbon Dot Dispersion with Adjusted CV Value (1) Preparation of Carbon Dot Dispersion A with CV Value of 10% (Aspect Ratio 1.0 to 1.3) Carbon Dot Dispersion 2 (with a particle size of 1.0 nm) Since the CV value of the carbon dots in the carbon dot dispersion liquid is 10%, the carbon dot dispersion liquid 2 was used as it was as the carbon dot dispersion liquid A (CV value 10%).

(2) Preparation of carbon dot dispersion B having a CV value of 15% (aspect ratio: 1.0 to 1.4) CV of carbon dots in carbon dot dispersion 1 (carbon dot dispersion having a particle size of 1.8 nm) Since the value was 15%, the carbon dot dispersion liquid 1 was used as it was as the carbon dot dispersion liquid B (CV value 15%).

(3) Preparation of carbon dot dispersion C having a CV value of 20% (aspect ratio 1.0 to 1.5) CV of carbon dots in carbon dot dispersion 3 (carbon dot dispersion having a particle size of 2.6 nm) Since the value was 20%, the carbon dot dispersion liquid 3 was used as it was as the carbon dot dispersion liquid C (CV value 20%).

(4) Preparation of carbon dot dispersion D having a CV value of 25% (aspect ratio: 1.0 to 1.6) CV of carbon dots in carbon dot dispersion 4 (carbon dot dispersion having a particle size of 3.0 nm) Since the value was 25%, the carbon dot dispersion liquid 4 was used as it was as a carbon dot dispersion liquid D (CV value 25%).

(5) Preparation of carbon dot dispersion E having a CV value of 30% (aspect ratio 1.0 to 1.6) Carbon dot dispersion 2 (carbon dot dispersion with a particle size of 1.0 nm) / carbon dot dispersion 1 (Carbon dot dispersion liquid with a particle diameter of 1.8 nm) / carbon dot dispersion liquid 4 (carbon dot dispersion liquid with a particle diameter of 3.0 nm) are mixed at a volume ratio of 0.5: 9.0: 0.5. Carbon dot dispersion E (CV value 30%, aspect ratio 1.0 to 1.6) was obtained.

(6) Preparation of carbon dot dispersion F having a CV value of 40% (aspect ratio 1.0 to 1.6) Carbon dot dispersion 2 (carbon dot dispersion with a particle size of 1.0 nm) / carbon dot dispersion 1 (Carbon dot dispersion liquid with a particle diameter of 1.8 nm) / carbon dot dispersion liquid 4 (carbon dot dispersion liquid with a particle diameter of 3.0 nm) are mixed at a volume ratio of 1.0: 8.0: 1.0. Carbon dot dispersion F (CV value 40%, aspect ratio 1.0 to 1.6) was obtained.

(7) Preparation of carbon dot dispersion G having a CV value of 30% (aspect ratio 1.3 to 2.0) by hydrothermal method 1 g of citric acid and 10 mL of water are mixed and used for an autoclave made of Teflon (registered trademark) Transferred to a container. Subsequently, a Teflon (registered trademark) autoclave container was sealed in a metal autoclave and treated at 200 ° C. for 5 hours to produce a carbon dot dispersion G (CV value 30%, aspect ratio 1.3 to 2.0). did.

4). Production of carbon dot inclusion body (1) Production of luminous body 1 (Example 1)
5 parts of the above carbon dot dispersion A (carbon dot dispersion having a CV value of 10% according to the template method), 10 parts of methyl methacrylate, 5 parts of anionic emulsifier Eleminol MON-7 (manufactured by Sanyo Chemical), and polymerization initiator Hydrogen peroxide water (0.1 part), water (500 parts), and toluene (500 parts) were mixed and stirred at 40 ° C. for 10 minutes to effect emulsion polymerization of methyl methacrylate. Subsequently, the product was filtered and the surface was washed with EtOH. Subsequently, by drying in vacuum for 10 hours, carbon dots having a CV value of 10% and an aspect ratio of 1.0 to 1.3 each containing carbon dot single inclusion particles encapsulated with an insulator are used for powdery light emission Body 1 was obtained.

(2) Production of luminous body 2 (Example 2)
Except for using carbon dot dispersion B (carbon dot dispersion having a CV value of 15% according to the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% according to the template method), the light emitter 1. A powder-form light-emitting body including the carbon dot single inclusion particles in which carbon dots having a CV value of 15% and an aspect ratio of 1.0 to 1.4 are encapsulated with an insulator, respectively, by performing the same process as in the production of No. 1 2 was obtained.

(3) Production of luminous body 3 (Example 3)
Except for using carbon dot dispersion C (carbon dot dispersion having a CV value of 20% by the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% by the template method), the light emitter 1. A powder-form light-emitting body comprising the same carbon dot-encapsulated particles in which carbon dots having a CV value of 20% and an aspect ratio of 1.0 to 1.5 are encapsulated with an insulator, respectively, by performing the same process as in the production of 1. 3 was obtained.

(4) Production of luminous body 4 (Example 4)
Mix 5 parts of carbon dot dispersion A (carbon dot dispersion with 10% CV value by template method) and 0.5 part of 3- (2-aminoethylamino) propyldimethoxymethylsilane, and react at 220 ° C. for 10 minutes. I let you. Subsequently, a powder-form light-emitting body including carbon dot single inclusion particles in which carbon dots having a CV value of 10% and an aspect ratio of 1.0 to 1.3 are included in an insulator by vacuum drying for 10 hours. 4 was obtained.

(5) Production of luminous body 5 (Example 5)
Except for using carbon dot dispersion B (carbon dot dispersion having a CV value of 15% according to the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% according to the template method), the light emitter 4 is a powder-like light-emitting body that includes the same carbon dot-encapsulated particles in which carbon dots having a CV value of 15% and an aspect ratio of 1.0 to 1.4 are each encapsulated with an insulator. 5 was obtained.

(6) Production of luminous body 6 (Example 6)
Except for using carbon dot dispersion C (carbon dot dispersion having a CV value of 20% by the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% by the template method), the light emitter 4 is a powder-like light-emitting body that includes the same carbon dot-encapsulated particles in which carbon dots having a CV value of 20% and an aspect ratio of 1.0 to 1.5 are each encapsulated with an insulator. 6 was obtained.

(7) Production of luminous body 7 (Example 7)
50 parts of EtOH was added to 0.1 part of the powdery illuminant 4 and dispersed with a disperser (Starburst Mini, manufactured by Sugino Machine Co.) to obtain a slurry-like illuminant 7.

(8) Production of luminous body 8 (Example 8)
50 parts of EtOH was added to 0.1 part of the powdery illuminant 5 and dispersed with a disperser (Starburst Mini, manufactured by Sugino Machine Co., Ltd.) to obtain a slurry illuminant 8.

(9) Production of luminous body 9 (Example 9)
50 parts of EtOH was added to 0.1 part of the powdery light emitter 6 and dispersed with a disperser (Starburst Mini, manufactured by Sugino Machine Co., Ltd.) to obtain a slurry light emitter 9.

(10) Production of luminous body 10 (Example 10)
1 g of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% according to the mold method) and 22.5 mL of water were mixed and heated at 70 ° C. for 20 minutes using a hot stirrer. To this dispersion, 0.5 g of Nicalac MX-035 (manufactured by Nippon Carbide Industries, Ltd., melamine resin) was added, and the mixture was further heated and stirred for 5 minutes. Further, 100 μL of formic acid was added, and the mixture was stirred with heating at 60 ° C. for 20 minutes, and then allowed to cool to room temperature. After allowing to cool, the reaction mixture was placed in a centrifuge tube and centrifuged at 12000 rpm for 20 minutes in a centrifuge to remove the supernatant. Then, the precipitate was redispersed in 1 mL of pure water to obtain a dispersion of resin particles. The obtained dispersion was put in an autoclave, heated at a rate of temperature increase of 10 ° C./min, held at 100 ° C. for 10 minutes, and then cooled at a rate of temperature decrease of 10 ° C./min. Then, by drying in vacuum for 10 hours, a powder-form light-emitting body containing carbon dot single inclusion particles in which carbon dots having a CV value of 10% and an aspect ratio of 1.0 to 1.3 are each included in an insulator 10 was obtained.

(11) Production of luminous body 11 (Example 11)
Except for using carbon dot dispersion B (carbon dot dispersion having a CV value of 15% according to the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% according to the template method), the light emitter 10 is a powdery luminescent material that includes the same carbon dot-encapsulated particles in which carbon dots having a CV value of 15% and an aspect ratio of 1.0 to 1.4 are each encapsulated with an insulator. 11 was obtained.

(12) Production of luminous body 12 (Example 12)
Except for using carbon dot dispersion C (carbon dot dispersion having a CV value of 20% by the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% by the template method), the light emitter 10 is a powdery luminescent material that includes the same carbon dot-encapsulated particles in which carbon dots having a CV value of 20% and an aspect ratio of 1.0 to 1.5 are each encapsulated with an insulator. 12 was obtained.

(13) Production of luminous body 13 (Comparative Example 1)
Except for using carbon dot dispersion G (carbon dot dispersion with 30% CV value by hydrothermal method) instead of carbon dot dispersion A (carbon dot dispersion with 10% CV value by template method), light emission The same process as the production of the body 1 is carried out, and the light emission in the form of a powder including carbon dots each having a CV value of 30% and an aspect ratio of 1.3 to 2.0 including carbon dot single inclusion particles encapsulated by an insulator. Body 13 was obtained.

(14) Production of luminous body 14 (Comparative Example 2)
Graphite oxide (0.1 g) was dispersed in 5 mL of a 0.2 mol / L urea aqueous solution. The obtained aqueous solution was heated in a sealed container at 150 ° C. for 10 hours. After heating, it was thoroughly washed to separate the nitrogen-containing graphene nanosheet. Next, 10 mg of polyacrylic acid (coating material) was dissolved in 5 mL of an aqueous dispersion in which 0.1 mg of nitrogen-containing graphene nanosheets were dispersed. The obtained solution was dried to obtain a nitrogen-containing graphene nanosheet / polyacrylic acid composite (light emitter 14) having a CV value of 40 and an aspect ratio of 4.0 to 50.0.

(15) Production of luminous body 15 (Comparative Example 3)
Carbon dot dispersion liquid A (carbon dot dispersion liquid with a CV value of 10% according to the mold method) is vacuum-dried to obtain a carbon dot powder having a CV value of 10%, a particle size of 2 nm, and an aspect ratio of 1.0 to 1.3 (light emitting body). 15) was obtained.

(16) Production of luminous body 16 (Example 13)
Except that the amount of the carbon dot dispersion A (carbon dot dispersion having a CV value of 10% according to the template method) was 50 parts in the production of the light emitter 1, the same process as that of the light emitter 1 was performed, and the CV value was 10%. A powdery light-emitting body 16 including a plurality of carbon dot inclusions in which an average of 10 carbon dots having an aspect ratio of 1.0 to 1.3 was included with an insulator was obtained.

(17) Production of luminous body 17 (Example 14)
Except for using carbon dot dispersion B (carbon dot dispersion having a CV value of 15% according to the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% according to the template method), the light emitter A process similar to that of No. 16 is performed, and includes a plurality of carbon dot inclusions in which an average of 10 carbon dots each having a CV value of 15% and an aspect ratio of 1.0 to 1.4 are included in an insulator. The light-emitting body 17 was obtained.

(18) Production of luminous body 18 (Example 15)
Except for using carbon dot dispersion C (carbon dot dispersion having a CV value of 20% by the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% by the template method), the light emitter A process similar to that of No. 16 is performed, and includes a plurality of carbon dot inclusions in which an average of 10 carbon dots having a CV value of 20% and an aspect ratio of 1.0 to 1.5 are included with an insulator. The light emitter 18 was obtained.

(19) Production of luminous body 19 (Example 16)
50 parts of carbon dot dispersion A (carbon dot dispersion with a CV value of 10% according to the template method), 5 parts of 3- (2-aminoethylamino) propyldimethoxymethylsilane, and 1 part of tetraethylorthosilicate were mixed. The reaction was carried out at 30 ° C. for 30 minutes. Subsequently, it is vacuum-dried for 10 hours, and contains a plurality of carbon dot inclusions each containing an average of 10 carbon dots having a CV value of 10% and an aspect ratio of 1.0 to 1.3. The light emitter 19 was obtained.

(20) Production of luminous body 20 (Example 17)
Except for using carbon dot dispersion B (carbon dot dispersion having a CV value of 15% according to the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% according to the template method), the light emitter A process similar to that of No. 19 is performed, and includes a plurality of carbon dot inclusions in which an average of 10 carbon dots having a CV value of 15% and an aspect ratio of 1.0 to 1.4 are included with an insulator. The luminous body 20 was obtained.

(21) Production of luminous body 21 (Example 18)
Except for using carbon dot dispersion C (carbon dot dispersion having a CV value of 20% by the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% by the template method), the light emitter 19 in the same manner as the production of No. 19, including a plurality of carbon dot inclusions in which an average of 10 carbon dots having a CV value of 20% and an aspect ratio of 1.0 to 1.5 are included with an insulator. The light emitter 21 was obtained.

(22) Production of luminous body 22 (Example 19)
50 parts of carbon dot dispersion A (carbon dot dispersion with a CV value of 10% according to the template method), 5 parts of 3- (2-aminoethylamino) propyldimethoxymethylsilane, and 1 part of tetraethylorthosilicate were mixed. The reaction was carried out at 30 ° C. for 30 minutes. Subsequently, by adding 10 parts of EtOH and stirring, a plurality of carbon dot inclusion bodies in which an average of 10 carbon dots having a CV value of 10% and an aspect ratio of 1.0 to 1.3 are included in an insulator are obtained. A powdery light emitter 22 was obtained.

(23) Production of luminous body 23 (Example 20)
Except for using carbon dot dispersion B (carbon dot dispersion having a CV value of 15% according to the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% according to the template method), the light emitter 22 including a plurality of carbon dot inclusion bodies in which an average of 10 carbon dots having a CV value of 15% and an aspect ratio of 1.0 to 1.4 are included in an insulator. The luminous body 23 was obtained.

(24) Production of luminous body 24 (Example 21)
Except for using carbon dot dispersion C (carbon dot dispersion having a CV value of 20% by the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% by the template method), the light emitter 22 in the form of a powder containing a plurality of carbon dot inclusions in which an average of 10 carbon dots each having a CV value of 20% and an aspect ratio of 1.0 to 1.5 are included in an insulator. The luminous body 24 was obtained.

(25) Production of luminous body 25 (Example 22)
Mix 50 parts of carbon dot dispersion A (carbon dot dispersion with a CV value of 10% according to the template method), 5 parts of 3- (2-aminoethylamino) propyldimethoxymethylsilane, and 1 part of tetraethylorthosilicate, and add Teflon. Poured into a (registered trademark) container. Subsequently, by reacting at 100 ° C. for 10 minutes, 150 ° C. for 10 minutes, and 220 ° C. for 30 minutes and taking out from the Teflon (registered trademark) container, carbon dots having a CV value of 10% and an aspect ratio of 1.0 to 1.3 are obtained. A plurality of light emitters 25 encapsulated with an insulator (sheet-like light emitters including carbon dot inclusions (0.5 μm thick)) were obtained.

(26) Production of luminous body 26 (Example 23)
Except for using carbon dot dispersion B (carbon dot dispersion having a CV value of 15% according to the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% according to the template method), the light emitter 25, a luminous body 26 (sheet-like shape including carbon dot inclusions) in which a plurality of carbon dots having a CV value of 15% and an aspect ratio of 1.0 to 1.4 are encapsulated with an insulator. A light emitter (0.5 μm thick) was obtained.

(27) Production of luminous body 27 (Example 24)
Except for using carbon dot dispersion C (carbon dot dispersion having a CV value of 20% by the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% by the template method), the light emitter The light emitting body 27 (sheet-like shape including the carbon dot inclusion body) in which a plurality of carbon dots having a CV value of 20% and an aspect ratio of 1.0 to 1.5 and including an insulator are included is performed in the same manner as the manufacture of No. 25. A light emitter (0.5 μm thick) was obtained.

(28) Production of luminous body 28 (Example 25)
A carbon dot inclusion was prepared in the same manner as the light emitter 10, except that the amount of the carbon dot dispersion liquid A (carbon dot dispersion liquid having a CV value of 10% according to the template method) was 50 g in the production of the light emitter 10, and the CV value was obtained. A powdery light-emitting body 28 including a plurality of carbon dots containing 10% of carbon dots having an average of 10% and an aspect ratio of 1.0 to 1.3 in an insulator was obtained.

(29) Production of luminous body 29 (Example 26)
Except for using carbon dot dispersion B (carbon dot dispersion having a CV value of 15% according to the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% according to the template method), the light emitter The same process as the production of No. 28 is performed, and a powder form including a plurality of carbon dot inclusion bodies in which an average of 10 carbon dots having a CV value of 15% and an aspect ratio of 1.0 to 1.4 is included with an insulator. The light emitting body 29 was obtained.

(30) Production of luminous body 30 (Example 27)
Except for using carbon dot dispersion C (carbon dot dispersion having a CV value of 20% by the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% by the template method), the light emitter The same process as the production of No. 28 is performed, and a powder form including a plurality of carbon dot inclusions each including an average of 10 carbon dots having a CV value of 20% and an aspect ratio of 1.0 to 1.5 and including an insulator. The light emitting body 30 was obtained.

(31) Production of luminous body 31 (Comparative Example 4)
Except for using carbon dot dispersion liquid G (carbon dot dispersion liquid with a CV value of 30% by hydrothermal method) instead of carbon dot dispersion liquid A (carbon dot dispersion liquid with a CV value of 10% according to the template method). The same process as that of No. 16 is performed, and a powder form including a plurality of carbon dot inclusion bodies in which an average of 10 carbon dots each having a CV value of 30% and an aspect ratio of 1.3 to 2.0 are included with an insulator. The phosphor 31 was obtained.

(32) Production of luminous body 32 (Comparative Example 5)
1 g of graphite oxide was dispersed in 50 mL of 0.2 mol / L urea aqueous solution. The obtained aqueous solution was heated in a sealed container at 150 ° C. for 10 hours. After heating, it was thoroughly washed to separate the nitrogen-containing graphene nanosheet. Next, 10 mg of polyacrylic acid (coating material) was dissolved in 5 mL of an aqueous dispersion in which 0.1 mg of nitrogen-containing graphene nanosheets were dispersed. The obtained solution was dried to obtain a nitrogen-containing graphene nanosheet / polyacrylic acid composite (light emitter 32) having a CV value of 40% and an aspect ratio of 4.0 to 50.0.

(33) Production of luminous body 33 (Comparative Example 6)
Except for using carbon dot dispersion E (carbon dot dispersion having a CV value of 30% according to the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% according to the template method), the light emitter 22 In the same manner as in the above, a powder-form containing a plurality of carbon dot inclusions in which an average of 10 carbon dots having a CV value of 30% and an aspect ratio of 1.0 to 1.6 are included with an insulator. The luminous body 33 was obtained.

(34) Production of luminous body 34 (Comparative Example 7)
Except for using carbon dot dispersion F (carbon dot dispersion having a CV value of 40% according to the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% according to the template method), the light emitter 22 In the same manner as the above, a powder-form containing a plurality of carbon dot inclusions each including an average of 10 carbon dots having a CV value of 40% and an aspect ratio of 1.0 to 1.6. The luminous body 34 was obtained.

(35) Production of luminous body 35 (Comparative Example 8)
Except for using carbon dot dispersion E (carbon dot dispersion having a CV value of 30% according to the template method) instead of carbon dot dispersion A (carbon dot dispersion having a CV value of 10% according to the template method), the light emitter 25 The light emitting body 35 (sheet (0. 0) comprising carbon dot inclusions) in which a plurality of carbon dots having a CV value of 30% and an aspect ratio of 1.0 to 1.6 are encapsulated with an insulator is performed. 5 μm thickness)).

(36) Production of luminous body 36 (Comparative Example 9)
Except for using carbon dot dispersion liquid F (carbon dot dispersion liquid with a CV value of 40% according to the template method) instead of the carbon dot dispersion liquid A (carbon dot dispersion liquid with a CV value of 10% according to the mold method), the luminous body 25 The light emitting body 36 (sheet-like light emission including the carbon dot inclusion body) in which a plurality of carbon dots having a CV value of 40% and an aspect ratio of 1.0 to 1.6 are encapsulated with an insulator is performed by performing the same process as in the above. Body (0.5 μm thick) was obtained.

(37) Production of luminous body 37 (Comparative Example 10)
10 g of C8 mesoporous silica was immersed in a 1M aqueous citric acid solution and left for 24 hours. Subsequently, using a Kiriyama glass filter, excess citric acid aqueous solution was removed, and C8 mesoporous silica in which the citric acid aqueous solution was soaked in the pore diameter was obtained. Subsequently, the C8 mesoporous silica impregnated with the citric acid aqueous solution is sintered at 400 ° C. for 3 hours, and includes a plurality of carbon dot inclusions in which carbon dots are arranged in the pores of the mesoporous silica, and the powdery light emitting body 37. Got. Note that the CV value and aspect ratio of the carbon dots of the illuminant 37 were considered to be the same as the carbon dot values in the carbon dot dispersion 2 prepared using C8 mesoporous silica, as in this experimental example.

5). Evaluation About the light-emitting body produced by the said Example and comparative example, the fluorescence intensity dispersion | variation between carbon dot inclusion bodies, a quantum yield, and wet heat tolerance were evaluated with the following method, respectively. In addition, the in-plane chromaticity variation was also evaluated for the sheet-like illuminant including a plurality of carbon dot inclusions. The results are shown in Tables 1 and 2.

(Fluorescence intensity variation between carbon dot inclusions)
Based on the average brightness when 20 carbon dot inclusions were photographed with a fluorescence microscope, the deviation from the reference brightness was evaluated according to the following criteria.
The brightness variation of all carbon dot inclusions falls within the average value of ± 2% ... ◎
The brightness variation of all carbon dot inclusions falls within the average value of ± 4%.
The brightness variation of all carbon dot inclusions falls within the average value of ± 6%.
The brightness variation of all carbon dot inclusions does not fall below the average value ± 6%.

(In-plane chromaticity variation)
The in-plane chromaticity variation of the sheet (bulk body) sample was determined by measuring light emission when the blue LED was used as a backlight from the back surface of the sheet (bulk body). The measuring device was a spectral radiance meter (CS-1000A, manufactured by Konica Minolta Sensing). The chromaticity is defined by a point where a straight line connecting a certain point and the origin intersects the plane x + y + z = 1 in the CIE-XYZ color system in which the color space is expressed in the XYZ coordinate system. Therefore, the chromaticity (x value and y value) at 10 locations was measured (z was omitted) for the light emission from the bulk body, and the standard deviations of the x value and the y value were obtained. And the average value of the standard deviation of x value and the standard deviation of y value was calculated, and the average value was evaluated according to the following criteria. If the standard deviation is small, it can be said that the chromaticity variation is small. If the standard deviation is less than 0.03, there is no chromaticity variation and there is no practical problem. The criteria are shown below.
Standard deviation is less than 0.02 ...
The standard deviation is 0.02 or more and less than 0.03 ...
The standard deviation is 0.03 or more and less than 0.04 ... △
Standard deviation is 0.04 or more.

(Fluorescence quantum yield evaluation)
For each phosphor, fluorescence quantum yield measurement was performed with an absolute PL quantum yield measuring apparatus (Quantaurus-QY C11347-01; manufactured by Hamamatsu Photonics). And the measured value was evaluated on the following reference | standard.
Quantum yield 60% or more ... ◎
Quantum yield 40% or more and less than 60%
Quantum yield 20% or more and less than 40% ・・・ △
Quantum yield less than 20%

(Wet heat resistance evaluation)
Each luminous body was stored in a constant temperature and humidity chamber at 85 ° C. and 85% Rh for 168 hours. At this time, the decrease width of the fluorescence intensity after storage relative to the fluorescence intensity (initial value) before storage was calculated and evaluated according to the following criteria. The fluorescence intensity of the illuminant was measured with a fluorometer.
Less than 10% decrease from the beginning ... ◎
Decrease from the beginning is 10% or more and less than 15%.
Decrease from initial is 15% or more and less than 20% ・・・ △
More than 20% decrease from the beginning ... ×

As shown in Table 1, each of the light emitters 1 to 12 including carbon dot single inclusion particles in which one carbon dot having a CV value (coefficient of variation) of 20% or less is coated with an insulator is included. There was little variation in fluorescence intensity between particles. Moreover, in these carbon dot single inclusion particle | grains, since the carbon dot was coat | covered with the insulator, the quantum yield was high and also the heat-and-moisture tolerance was excellent. On the other hand, when the CV value was increased, the variation in fluorescence intensity between the carbon dot single inclusion particles was likely to be increased (light emitters 13 and 14). Further, when the carbon dots were not covered with an insulator, the quantum yield was low and the wet heat resistance was low (light emitter 15).

Also, when the insulator was an aminosilane coupling agent or melamine resin, the quantum yield was likely to increase (light emitters 4 to 12). In the luminous body, an amide bond is formed at the interface between the carbon dots of the carbon dot-only inclusion particles and the insulator. Therefore, it is presumed that the functional group on the carbon dot surface was fixed and it was difficult for energy loss to occur. Further, when the component constituting the insulator contains a siloxane bond, the resistance to wet heat by the insulator is increased (for example, the light emitters 4 to 6).

Further, as shown in Table 2, even in the light emitters 13 to 30 including a plurality of carbon dot inclusion bodies in which a plurality of carbon dots having a CV value (coefficient of variation) of 20% or less are coated with an insulator, carbon dot single inclusions are included. There was little variation in fluorescence intensity between bodies. Moreover, in these carbon dot multiple inclusion bodies, since the carbon dot was coat | covered with the insulator, the quantum yield was high and also wet heat tolerance was excellent. On the other hand, when the CV value increases, the variation in fluorescence intensity among the carbon dot inclusion bodies tends to increase (light emitters 31 to 36). Further, when the carbon dots were not covered with an insulator, the quantum yield was low and the wet heat resistance was low (light emitting body 37).

The carbon dot inclusion body included in the light emitter of the present invention has a high quantum yield and a uniform fluorescence intensity. In addition, the chromaticity of the fluorescence emitted by the carbon dots included in each carbon dot inclusion is small, and the light emission life is long. Therefore, the light emitter of the present invention can be applied to various uses such as a fluorescent probe and an illumination device.

DESCRIPTION OF SYMBOLS 1 Carbon dot 2 Insulator 3 Carbon dot inclusion 3a Carbon dot single inclusion particle 3b Carbon dot multiple inclusion 10 Substrate 20 LED element 30 Wavelength conversion layer 50 LED device 100 Color wheel 101 Substrate 102 Light adjustment layer 110

Light source

111, 112 Lens DESCRIPTION OF SYMBOLS 113 Mirror 114 Projection optical system 120 Projection type display apparatus 200 Backlight apparatus 201 Wavelength conversion layer 202 Light source 203 Light guide body 300 Photoelectric conversion apparatus 301 Substrate 302 Electrode layer 303 P type semiconductor layer 304 N type semiconductor layer 305 Transparent electrode layer 310 Wavelength Conversion layer

Claims

A carbon dot inclusion body having carbon dots and an insulator covering the carbon dots,
The luminous body whose coefficient of variation of the particle size of the carbon dot is 20% or less.
The carbon dot inclusion body is a carbon dot single inclusion particle in which the one carbon dot is covered with the insulator,
The luminous body is in the form of powder or slurry,
The light emitter according to claim 1.
The carbon dot inclusion body is a carbon dot multiple inclusion body in which two or more carbon dots are coated with the insulator,
The luminous body is powdery, slurryy, or bulky,
The light emitter according to claim 1.
The ratio (b / a) between the short diameter a and the long diameter b of the carbon dots is in the range of 1.0 to 1.5.
The light emitter according to any one of claims 1 to 3.
The carbon dots and the insulator are chemically bonded at the interface between the carbon dots and the insulator.
The light emitter according to any one of claims 1 to 4.
The chemical bond is an amide bond;
The light emitter according to claim 5.
The insulator includes a metalloxane bond;
The light emitter according to any one of claims 1 to 6.
A method for producing a light emitter according to any one of claims 1 to 7,
A step of sintering a carbon compound in the pores of mesoporous silica to obtain the carbon dots;
Coating the carbon dots with the insulator;
including,
A method for manufacturing a luminous body.