JP2018039971A - Semiconductor nanoparticles, method of producing semiconductor nanoparticles, and light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ternary or quaternary semiconductor nanoparticle that enables the band-edge emission and has a less toxic composition.SOLUTION: A semiconductor nanoparticle is provided that contains Ag, In, and S and has an average particle size of 50 nm or less. The ratio of the number of atoms of Ag to the total number of atoms of Ag and In is 0.320 or more and 0.385 or less, and the ratio of the number of atoms of S to the total number of atoms of Ag and In is 1.20 or more and 1.45 or less. The semiconductor nanoparticle is adapted to emit light having an emission lifetime of 200 ns or less upon being irradiated with light having a wavelength in a range of 350 nm to 500 nm.SELECTED DRAWING: None

Description

  The present invention relates to semiconductor nanoparticles, a method for producing the same, and a light-emitting device using the semiconductor nanoparticles.

  As a white light emitting device used for a backlight of a liquid crystal display device, a device using light emission of a quantum dot (also called a semiconductor quantum dot) has been proposed. Semiconductor fine particles are known to exhibit a quantum size effect when their particle size is, for example, 10 nm or less, and such nanoparticles are called quantum dots. The quantum size effect is a phenomenon in which the valence band and conduction band, which are considered continuous in bulk particles, become discrete when the particle size is nano-sized, and the band gap energy changes according to the particle size. Point to.

  Since the quantum dot absorbs light and emits light corresponding to its band gap energy, it can be used as a wavelength conversion material in a light emitting device. For example, Patent Documents 1 and 2 propose light-emitting devices using quantum dots. Specifically, a part of the light emitted from the LED chip is absorbed by the quantum dots, light of another color is emitted, and the light emitted from the quantum dots and the LED chip that is not absorbed by the quantum dots It has been proposed to obtain white light by mixing with the above light. In these patent documents, it is proposed to use quantum dots of Group 12 to Group 16 such as CdSe and CdTe, and Group 14 to Group 16 such as PbS and PbSe.

JP 2012-212862 A JP 2010-177656 A

  One advantage of using quantum dots in a light emitting device is that light having a wavelength corresponding to the band gap is obtained as a peak having a relatively narrow half-value width. Among the quantum dots proposed as wavelength converting substances, light having a wavelength corresponding to the band gap, that is, those in which band edge emission has been confirmed, are binary elements represented by Group 12 to Group 14 such as CdSe. It is a quantum dot made of a series semiconductor. However, band edge emission has not been confirmed for ternary quantum dots, particularly those belonging to Group 11-Group 13-Group 16.

  The light emitted from the group 11-group 13-group 16 quantum dots originates from the surface of the particle, internal defect levels, or donor-acceptor pair recombination, so the emission peak is broad. It has a wide half-value width and a long light emission lifetime. Such light emission is not particularly suitable for a light-emitting device used in a liquid crystal display device. This is because a light-emitting device used in a liquid crystal display device is required to emit light with a narrow half-value width having peak wavelengths corresponding to the three primary colors (RGB) in order to ensure high color reproducibility. Therefore, ternary quantum dots have not been put into practical use even though they can have a low toxicity composition.

  An object of the embodiment of the present invention is to provide a semiconductor nanoparticle having a configuration capable of obtaining band edge emission from a ternary quantum dot that can have a low toxicity composition, and a method for producing the same.

An embodiment according to the present invention is a method for producing semiconductor nanoparticles by reacting an Ag salt, an In salt, and a compound serving as a source of S in an organic solvent,
(A) preparing an Ag salt, an In salt, a compound serving as a source of S, and an organic solvent;
(B) the Ag salt, the In salt, and the S source so that the ratio of the number of Ag atoms to the total number of Ag and In atoms is 0.33 or more and 0.42 or less; A compound to be formed in the organic solvent to produce semiconductor nanoparticles,
A method for producing semiconductor nanoparticles containing

Another embodiment according to the present invention is to prepare a dispersion in which semiconductor nanoparticles produced by the method for producing semiconductor nanoparticles according to the above embodiment are dispersed in a solvent,
A compound containing a group 13 element and a group 16 element or a compound containing a group 16 element are added to the dispersion to substantially add the group 13 element and the group to the surface of the semiconductor nanoparticle. It is a manufacturing method of a core-shell type semiconductor nanoparticle including forming a semiconductor layer composed of a group 16 element.

Still another embodiment according to the present invention is a semiconductor nanoparticle containing Ag, In, and S having an average particle size of 50 nm or less,
The ratio of the number of Ag atoms to the total number of Ag and In atoms is 0.320 or more and 0.385 or less,
The ratio of the number of S atoms to the total number of Ag and In atoms is 1.20 or more and 1.45 or less,
When light having a wavelength in the range of 350 to 500 nm is irradiated, it emits light having an emission lifetime of 200 ns or less.
Semiconductor nanoparticles.

Yet another embodiment according to the present invention is a core-shell type semiconductor nanoparticle comprising a core and a shell that covers the surface of the core and heterojunction with the core,
The core includes Ag, In, and S, the ratio of the number of Ag atoms to the total number of Ag and In atoms is not less than 0.320 and not more than 0.385, and S relative to the total number of Ag and In atoms The ratio of the number of atoms of the semiconductor is 1.20 or more and 1.45 or less,
The shell is a semiconductor substantially composed of a Group 13 element and a Group 16 element;
In the emission spectrum obtained when light having a wavelength in the range of 350 to 500 nm is irradiated, an emission peak having a peak wavelength in the range of 550 nm to 650 nm and a half width of 80 nm or less is observed.
Core-shell type semiconductor nanoparticles.

  Yet another embodiment of the present invention is a light emitting device including a light conversion member and a semiconductor light emitting element, wherein the light conversion member includes the semiconductor nanoparticles of the embodiment according to the present invention. is there.

  The semiconductor nanoparticles of the embodiment according to the present invention are made of a semiconductor containing Ag, In, and S, which are elements of Group 11, Group 13, and Group 16, respectively, with respect to the total number of Ag and In atoms. The ratio of the number of Ag atoms and the ratio of the number of S atoms to the total number of Ag and In atoms are within a specific range, respectively, and emission having a short emission lifetime, that is, band edge emission is obtained. Yes. The semiconductor nanoparticles can have a composition that does not contain Cd and Pb, which are considered to be highly toxic, and can also be applied to products that prohibit the use of Cd and the like. Therefore, the semiconductor nanoparticles can be suitably used as a wavelength conversion substance for a light-emitting device used in a liquid crystal display device or the like, or as a biomolecule marker. Furthermore, according to the method for producing semiconductor nanoparticles described above, it is possible to relatively easily produce ternary semiconductor nanoparticles that give band edge emission.

2 is an XRD pattern of semiconductor nanoparticles of Example 2. FIG. It is an absorption spectrum of the semiconductor nanoparticle of Examples 1-3. It is an emission spectrum of the semiconductor nanoparticle of Examples 1-3. It is an absorption spectrum of the semiconductor nanoparticle of Example 4 and Comparative Examples 1-2. It is an emission spectrum of the semiconductor nanoparticle of Example 4 and Comparative Examples 1-2. 6 is an emission / absorption spectrum of a core (primary semiconductor nanoparticles) produced in Example 5. 6 is an emission / absorption spectrum of core-shell type semiconductor nanoparticles prepared in Example 5. 6 is a HAADF image of core-shell type semiconductor nanoparticles prepared in Example 5. FIG. 6 is a HAADF image of the core (primary semiconductor nanoparticles) produced in Example 5. FIG.

  Hereinafter, embodiments will be described in detail. However, this invention is not limited to the form shown below. In addition, the matters described in the embodiments and the modifications thereof can be applied to other embodiments and modifications unless otherwise specified.

(First embodiment: semiconductor nanoparticles)
As a first embodiment, semiconductor nanoparticles containing Ag, In and S will be described.
The semiconductor nanoparticles of this embodiment are semiconductor nanoparticles containing Ag, In, and S and having an average particle size of 50 nm or less. The crystal structure of the semiconductor nanoparticles may be at least one selected from the group consisting of tetragonal, hexagonal, and orthorhombic.

Semiconductor nanoparticles containing the above-mentioned specific elements and having a crystal structure of tetragonal, hexagonal or orthorhombic are generally introduced in the literature, etc., as expressed by the composition formula of AgInS ₂ Has been. Note that a semiconductor represented by the composition formula of AgInS ₂ and having a hexagonal crystal structure is a wurtzite type, and a semiconductor having a tetragonal crystal structure is a chalcopyrite type. The crystal structure is identified, for example, by measuring an XRD pattern obtained by X-ray diffraction (XRD). Specifically, the XRD pattern obtained from the semiconductor nanoparticles is compared with the XRD pattern known as that of the semiconductor nanoparticles represented by the composition of AgInS ₂ or the XRD pattern obtained by performing simulations from crystal structure parameters. To do. If there is a known pattern and a simulation pattern that match the semiconductor nanoparticle pattern, the crystal structure of the semiconductor nanoparticle can be said to be the crystal structure of the matching known or simulated pattern.

  In the aggregate of nanoparticles, nanoparticles having different crystal structures may be mixed. In that case, in the XRD pattern, peaks derived from a plurality of crystal structures are observed.

In order to obtain a semiconductor represented by the composition formula of AgInS ₂ , the ratio (preparation ratio) of the compounds serving as the Ag source, the In source, and the S source is selected so as to satisfy the stoichiometric composition. It is common to synthesize. The inventors of the present invention have found that when a semiconductor composed of Ag, In, and S or a semiconductor containing these elements has a composition deviating from the stoichiometric composition ratio, band edge emission can be obtained. investigated. As a result, the preparation ratio of each element source is selected so that the ratio of the number of Ag atoms to the total number of Ag and In atoms is 0.33 or more and 0.42 or less, as will be described later. It was found that semiconductor nanoparticles capable of emitting light at the band edge, although having a non-stoichiometric composition, can be obtained.

  In the semiconductor nanoparticles of this embodiment, the ratio of the number of Ag atoms to the total number of Ag and In atoms (Ag / Ag + In) is 0.320 or more and 0.385 or less, and the total number of Ag and In atoms is The ratio of the number of S atoms to (S / Ag + In) is 1.20 or more and 1.45 or less. That Ag / Ag + In is 0.320 or more and 0.385 or less means that In is contained at a ratio higher than the stoichiometric composition ratio. Moreover, that S / Ag + In is 1.20 or more and 1.45 or less means that S is contained in a proportion higher than the stoichiometric composition ratio. When Ag, In, and S are contained according to the stoichiometric composition, Ag / Ag + In becomes 0.5 and S / Ag + In becomes 1.

The reason why the semiconductor nanoparticles of the present embodiment give relatively strong band edge emission is not clear, but for example, In and S form In ₂ S ₃ , which may have some influence. Inferred. However, this inference does not limit the invention described in the claims.

  In this embodiment, Ag / Ag + In is 0.320 or more and 0.385 or less, particularly 0.350 or more and 0.382 or less, and S / Ag + In is 1.20 or more and 1.45 or less. It is 25 or more and 1.40 or less. When Ag / Ag + In and S / Ag + In are within these ranges, it is easy to obtain band edge light emission or to obtain band edge light emission having a larger light emission intensity.

  The chemical composition of the semiconductor nanoparticles can be identified, for example, by energy dispersive X-ray analysis or fluorescent X-ray analysis (XRF). Ag / Ag + In and S / Ag + In are calculated based on the chemical composition measured by any of these methods.

  The nanoparticles of the first embodiment may consist essentially of Ag, In and S only. Here, the term “substantially” is used in consideration of the fact that elements other than Ag, In, and S are inevitably included due to contamination of impurities and the like. Alternatively, the nanoparticles of the first embodiment may contain other elements as long as Ag / Ag + In and S / Ag + In are within the above ranges.

  The semiconductor nanoparticles of this embodiment have an average particle size of 50 nm or less. The average particle diameter may be, for example, in the range of 1 nm to 20 nm, in particular in the range of 1 nm to 10 nm. When the average particle size exceeds 50 nm, it becomes difficult to obtain the quantum size effect, and it becomes difficult to obtain band edge emission.

  The average particle diameter of the nanoparticles may be determined from, for example, a TEM image taken using a transmission electron microscope (TEM). Specifically, it is a line segment connecting two arbitrary points on the outer periphery of the particle observed in the TEM image, and indicates the longest line segment passing through the center of the particle.

  However, when the particles have a rod-like shape, the length of the minor axis is regarded as the particle size. Here, the rod-shaped particles are observed as quadrangular shapes including a rectangular shape (the cross section has a circle, ellipse, or polygonal shape), an elliptical shape, or a polygonal shape (for example, a shape like a pencil). The ratio of the length of the long axis to the length of the short axis is greater than 1.2. For rod-shaped particles, the length of the long axis is the longest of the line segments connecting any two points on the outer periphery of the particle in the case of an elliptical shape, and in the case of a rectangular or polygonal shape The longest of the line segments connecting any two points on the outer periphery of the particle and parallel to the longest side among the sides defining the outer periphery. The length of the short axis refers to the longest segment that is orthogonal to the segment that defines the length of the major axis among the segments connecting any two points on the outer periphery.

The average particle diameter is measured for all measurable nanoparticles observed in a 50,000-fold to 150,000-fold TEM image, and is the arithmetic average of the particle diameters. Here, “measurable” particles are those in which the entire particles can be observed in a TEM image. Accordingly, a part of the TEM image is not included in the imaging range, and particles that are “cut” are not measurable.
When a total of 100 or more nanoparticles are included in one TEM image, the average particle diameter is obtained using one TEM image. When the number of nanoparticles included in one TEM image is small, the imaging location is changed to further obtain a TEM image, and the particle size is measured for 100 or more particles included in two or more TEM images. .

  The semiconductor nanoparticles of the present embodiment can emit band edge emission due to Ag / Ag + In and S / Ag + In being in the above ranges. Specifically, when the semiconductor nanoparticles of this embodiment are irradiated with light having a wavelength in the range of 350 nm to 500 nm, the semiconductor nanoparticles have a longer wavelength than the irradiated light and have a light emission lifetime of 200 ns or less. Can emit light. In addition, light emission with an emission lifetime of 200 ns or less is preferably observed with a half-value width of 150 nm or less in the emission spectrum provided by the semiconductor nanoparticles.

The light emission lifetime is determined according to the following procedure. First, semiconductor nanoparticles are irradiated with excitation light to emit light, and the decay (afterglow) of light having a wavelength in the vicinity of the peak of the emission spectrum, for example, a wavelength within the range of (peak wavelength ± 50 nm), over time. Measure changes. The change with time is measured from the point of time when the irradiation of the excitation light is stopped. The attenuation curve obtained is generally a combination of a plurality of attenuation curves derived from relaxation processes such as light emission and heat. Therefore, in the present embodiment, it is assumed that three components (that is, three attenuation curves) are included, and the parameter is set so that the attenuation curve can be expressed by the following equation when the emission intensity is I (t). Perform fitting. Parameter fitting is performed using dedicated software.
I (t) = A ₁ exp (−t / τ ₁ ) + A ₂ exp (−t / τ ₂ ) + A ₃ exp (−t / τ ₃ )

In the above formula, τ ₁ , τ ₂ , and τ ₃ of each component are the time required for the light intensity to decay to 1 / e (36.8%) of the initial stage, which corresponds to the emission lifetime of each component. To do. Τ ₁ , τ ₂ , and τ ₃ are set in order from the shortest emission lifetime. A ₁ , A ₂ and A ₃ are contribution rates of the respective components. In the present embodiment, when a component having the largest integral value of a curve represented by A _x exp (−t / τ _x ) is used as a main component, τ of the main component is used as light (the above-mentioned light emission lifetime measured). The emission lifetime of light having a wavelength near the peak). And it is guessed that the light emission whose light emission lifetime is 200 ns or less is band edge light emission. In specifying the principal component, A _x × τ _x obtained by integrating the value of t of A _x exp (−t / τ _x ) from 0 to infinity is compared, and this value is the largest. Is the main component.

  In this embodiment, assuming that the emission attenuation curve includes three, four, or five components, the difference between the attenuation curve drawn by the equation obtained by performing the parameter fitting and the actual attenuation curve is as follows. , Not much changed. For this reason, in the present embodiment, when obtaining τ of the main component, it is assumed that the number of components included in the emission attenuation curve is 3, thereby avoiding complicated parameter fitting.

  The emission spectrum of the semiconductor nanoparticles of the present embodiment is obtained when light having a specific wavelength selected from the range of 350 nm to 1100 nm is irradiated. For example, in the case of nanoparticles having a tetragonal crystal structure, Ag / Ag + In of 0.361 and S / Ag + In of 1.30 (corresponding to Example 2 described later), irradiation with light having a wavelength of 365 nm, As shown by a dotted line in FIG. 3, an emission spectrum in which an emission peak derived from band edge emission is observed in the vicinity of 590 nm can be obtained.

  The semiconductor nanoparticles of the present embodiment may provide other light emission, for example, defect light emission, together with band edge light emission. Defect emission generally has a long emission lifetime, has a broad spectrum, and has a peak at a longer wavelength than band edge emission. When both band edge emission and defect emission are obtained, it is preferable that the intensity of band edge emission is greater than the intensity of defect emission.

  The band edge emission emitted from the semiconductor nanoparticles of the present embodiment can be changed in its peak position by changing the shape and / or average particle size, particularly the average particle size, of the semiconductor nanoparticles. For example, if the average particle size of the semiconductor nanoparticles is made smaller, the band gap energy becomes larger due to the quantum size effect, and the peak wavelength of the band edge emission can be shifted to the short wavelength side.

  The absorption spectrum of the semiconductor nanoparticles of this embodiment can be obtained by irradiating light having a wavelength selected from a predetermined range. For example, in the case of a nanoparticle having a tetragonal crystal structure, Ag / Ag + In of 0.361 and S / Ag + In of 1.30 (corresponding to Example 2 described later), light with a wavelength of 190 nm to 1100 nm is irradiated. Then, an absorption spectrum as shown by a solid line in FIG. 2 can be obtained. FIG. 2 shows an absorption spectrum having a wavelength of about 190 nm to 1100 nm and a wavelength range of about 350 nm to 750 nm.

  The semiconductor nanoparticles of this embodiment also preferably have an absorption spectrum that exhibits an exciton peak. The exciton peak is a peak obtained by exciton generation, and the fact that it is expressed in the absorption spectrum means that the particle has a small particle size distribution and is suitable for band edge emission with few crystal defects. . As the exciton peak becomes steeper, it means that more particles with a uniform crystal size and fewer crystal defects are contained in the aggregate of semiconductor nanoparticles. Therefore, the half-value width of light emission becomes narrower, and the light emission efficiency is improved. is expected. In the absorption spectrum of the semiconductor nanoparticles of the present embodiment, the exciton peak is observed within a range of 350 nm to 650 nm, for example.

  The surface of the semiconductor nanoparticles of this embodiment may be modified with an arbitrary compound. A compound that modifies the surface of the nanoparticle is also called a surface modifier. The surface modifier is, for example, for stabilizing the nanoparticles to prevent aggregation or growth of the nanoparticles and / or for improving the dispersibility of the nanoparticles in the solvent.

  In this embodiment, the surface modifier is, for example, a nitrogen-containing compound having a hydrocarbon group having 4 to 20 carbon atoms, a sulfur-containing compound having a hydrocarbon group having 4 to 20 carbon atoms, or a hydrocarbon having 4 to 20 carbon atoms. It may be an oxygen-containing compound having a group. Examples of the hydrocarbon group having 4 to 20 carbon atoms include saturated aliphatic carbonization such as n-butyl group, isobutyl group, n-pentyl group, n-hexyl group, octyl group, decyl group, dodecyl group, hexadecyl group and octadecyl group. An unsaturated aliphatic hydrocarbon group such as an oleyl group; an alicyclic hydrocarbon group such as a cyclopentyl group or a cyclohexyl group; an aromatic hydrocarbon group such as a phenyl group, a benzyl group, a naphthyl group, or a naphthylmethyl group; Of these, saturated aliphatic hydrocarbon groups and unsaturated aliphatic hydrocarbon groups are preferred. Examples of nitrogen-containing compounds include amines and amides, examples of sulfur-containing compounds include thiols, and examples of oxygen-containing compounds include fatty acids.

  As the surface modifier, a nitrogen-containing compound having a hydrocarbon group having 4 to 20 carbon atoms is preferable. Such nitrogen-containing compounds include, for example, alkylamines such as n-butylamine, isobutylamine, n-pentylamine, n-hexylamine, octylamine, decylamine, dodecylamine, hexadecylamine, octadecylamine, and alkenylamines such as oleylamine. It is.

  As the surface modifier, a sulfur-containing compound having a hydrocarbon group having 4 to 20 carbon atoms is preferable. Such sulfur-containing compounds are, for example, n-butanethiol, isobutanethiol, n-pentanethiol, n-hexanethiol, octanethiol, decanethiol, dodecanethiol, hexadecanethiol, octadecanethiol, and the like.

  Two or more different surface modifiers may be used in combination. For example, one compound selected from the nitrogen-containing compounds exemplified above (for example, oleylamine) and one compound selected from the sulfur-containing compounds exemplified above (for example, dodecanethiol) may be used in combination. .

(Second Embodiment: Method for Producing Semiconductor Nanoparticles)
Next, as a second embodiment, a method for manufacturing the semiconductor nanoparticles of the first embodiment will be described. The production method of the present embodiment is a method of producing semiconductor nanoparticles by reacting an Ag salt, an In salt, and a compound serving as a source of S in an organic solvent,
(A) preparing an Ag salt, an In salt, a compound serving as a source of S, and an organic solvent;
(B) an Ag salt, an In salt, and a compound serving as a source of S so that the ratio of the number of Ag atoms to the total number of Ag and In atoms is 0.33 or more and 0.42 or less; In the organic solvent to produce semiconductor nanoparticles,
The manufacturing method of the semiconductor nanoparticle containing this. In this production method, the Ag salt, the In salt, and the S salt are adjusted so that the ratio of the number of Ag atoms to the total number of Ag and In atoms (Ag / Ag + In) is 0.33 or more and 0.42 or less. A compound serving as a supply source of is put in an organic solvent. By supplying the source of each element so that Ag / Ag + In falls within the above range, Ag—In—S semiconductor nanoparticles having Ag / Ag + In within the range described in the first embodiment are obtained. be able to. That is, the manufacturing method of the present embodiment is characterized in that semiconductor nanoparticles are generated by using a specific ratio that does not match the stoichiometric composition ratio of the supply source of each element.

<First Semiconductor Nanoparticle Generation Method>
The production of the semiconductor nanoparticles is, for example, a complex obtained by mixing a salt of Ag, a salt of In, a compound serving as a supply source of S, and a compound capable of forming a complex with S as a coordination element, The complex may be made by a method including heat treatment. As for the salt of Ag and the salt of In, the kind is not specifically limited, Any of organic acid salt and inorganic acid salt may be sufficient. Specifically, the salt may be any of nitrate, acetate, sulfate, hydrochloride, and sulfonate, and is preferably an organic acid salt such as acetate. This is because the organic acid salt has high solubility in an organic solvent and facilitates the reaction to proceed more uniformly.

  Examples of compounds used as a supply source of S used in this production method include β-dithiones such as 2,4-pentanedithione; 1,2-bis (trifluoromethyl) ethylene-1,2-dithiol, and the like. Dithiols; diethyldithiocarbamate; thiourea.

  The complex is obtained by mixing a salt of Ag, a salt of In, and a compound that is a source of S. The complex is formed by mixing an Ag salt, an In salt, and a compound serving as a source of S into water or an organic solvent (particularly, an organic solvent having a high polarity such as ethanol, methanol, acetone). May be implemented.

  The organic solvent can be the surface modifier itself or can include a surface modifier. The surface modifier is as described in relation to the first embodiment. In particular, the organic solvent includes at least one solvent selected from thiols having a hydrocarbon group having 4 to 20 carbon atoms and at least one solvent selected from amines having a hydrocarbon group having 4 to 20 carbon atoms. It is preferable to use an organic solvent consisting of or a combination thereof.

  In production procedures involving complex formation, the solvent is selected such that the complex is formed. For example, when water or an organic solvent cannot dissolve the Ag salt, the In salt, and the compound serving as the source of S, the complex is not formed or the complex is hardly formed. However, even when the organic solvent cannot dissolve the Ag salt, the In salt, and the compound serving as the source of S, depending on the combination of the compounds serving as the source of each element, the following “second semiconductor nanoparticles” As will be described in the section “Generation Method”, semiconductor nanoparticles may be generated without the compound serving as the source of S functioning as a ligand.

  Here, the ratio of the number of Ag atoms to the total number of Ag and In atoms (Ag / Ag + In) is 0.33 or more and 0.42 or less in the Ag salt, the In salt, and the compound serving as the source of S. Is used in such an amount. Further, it is preferable to use the compound serving as the supply source of S in such an amount that the ratio of the number of S atoms to the total number of Ag and In atoms (S / Ag + In) is 0.95 or more and 1.20 or less. . By using a compound serving as a supply source of each element so as to satisfy these conditions, it is possible to generate semiconductor nanoparticles that easily give band-edge light emission or have high intensity of band-edge light emission.

  Ag / Ag + In is more preferably 0.38 or more and 0.42 or less, and particularly 0.40. Further, S / Ag + In is more preferably 0.95 or more and 1.10 or less, and particularly 1.00.

  Next, the obtained complex is heat-treated to form semiconductor nanoparticles. The heat treatment of the complex is carried out by using a surface modifier or a solvent containing a surface modifier and adding a salt and a compound serving as a source of S, followed by heat treatment to form a complex, heat treatment and surface modification. May be carried out in a manner that is carried out continuously or simultaneously.

  The heat treatment is preferably performed at a temperature of 230 ° C. or higher and 260 ° C. or lower for 3 minutes or longer. The heating time is more preferably 5 minutes or more, even more preferably 8 minutes or more, and most preferably 10 minutes or more. A more preferable heating temperature is 245 ° C. or more and 255 ° C. or less, and may be particularly 250 ° C. The heating time is, for example, 60 minutes or less, particularly 30 minutes or less. The heating time may be 10 minutes.

Alternatively, the heat treatment may be performed by heating at a temperature of 30 ° C. or higher and 190 ° C. or lower for 1 minute or longer and 15 minutes or lower and then heating at a temperature of 230 ° C. or higher and 260 ° C. or lower for 3 minutes or longer. . In the case where the heat treatment is performed in two stages, it is easy to obtain semiconductor nanoparticles having higher band edge emission intensity. In this case, the heating temperature in the first stage is more preferably 45 ° C. to 155 ° C., even more preferably 145 ° C. to 155 ° C., and particularly 150 ° C. The heating time of the first stage is more preferably 8 minutes or more and 13 minutes or less, still more preferably 9 minutes or more and 11 minutes or less, and particularly 10 minutes. The heating time of the second stage is more preferably 5 minutes or more, even more preferably 8 minutes or more, and most preferably 10 minutes or more. The heating temperature in the second stage is more preferably 245 ° C. or more and 255 ° C. or less, and particularly 250 ° C. The heating time of the second stage is, for example, 60 minutes or less, particularly 30 minutes or less. The heating time may be 10 minutes.
By carrying out the heat treatment in two stages, semiconductor nanoparticles having a relatively high band edge emission intensity can be produced with good reproducibility.

<Method for generating second semiconductor nanoparticles>
The semiconductor nanoparticles may be produced by a method in which an Ag salt, an In salt, and a compound serving as a source of S are added to an organic solvent at a time, and then the organic solvent is heated. According to this method, it is possible to synthesize nanoparticles with a single pod with high reproducibility by a simple operation.
Alternatively, the organic solvent is reacted with an Ag salt to form a complex, and then the organic solvent is reacted with an In salt to form a complex. And the resulting reaction product may be produced by crystal growth. In this case, the heating is carried out at the stage of reacting with the compound serving as the supply source of S.
The salt of Ag and the salt of In are as described in relation to the production method (formation method of the first semiconductor nanoparticles) including the formation of the complex.

  The organic solvent is, for example, an amine having a hydrocarbon group having 4 to 20 carbon atoms, particularly an alkylamine or alkenylamine having 4 to 20 carbon atoms, a thiol having a hydrocarbon group having 4 to 20 carbon atoms, particularly 4 carbon atoms. Alkyl thiol or alkenyl thiol having -20, phosphine having a hydrocarbon group having 4 to 20 carbon atoms, particularly alkyl phosphine or alkenyl phosphine having 4 to 20 carbon atoms. These organic solvents ultimately modify the surface of the resulting semiconductor nanoparticles. These organic solvents may be used in combination of two or more, and in particular, at least one solvent selected from thiols having a hydrocarbon group having 4 to 20 carbon atoms and amines having a hydrocarbon group having 4 to 20 carbon atoms. A mixed solvent in combination with at least one solvent selected from may be used. These organic solvents may also be used as a mixture with other organic solvents.

  In the second generation method, the compound serving as the supply source of S is, for example, sulfur, thiourea, thioacetamide, or alkylthiol.

  Even when this generation method is adopted, the ratio of the number of Ag atoms to the total number of Ag and In atoms (Ag / Ag + In) is 0.33 in the Ag salt, In salt, and S source compound. The amount used is 0.42 or less. Further, it is preferable to use the compound serving as the supply source of S in such an amount that the ratio of the number of S atoms to the total number of Ag and In atoms (S / Ag + In) is 0.95 or more and 1.20 or less. . By using a compound serving as a supply source of each element so as to satisfy these conditions, semiconductor nanoparticles that easily give band-end emission can be generated.

  Ag / Ag + In is more preferably 0.38 or more and 0.42 or less, and particularly 0.40. Further, S / Ag + In is more preferably 0.95 or more and 1.10 or less, and particularly 1.00.

  Moreover, it is preferable to implement heat processing for 3 minutes or more at the temperature of 230 degreeC or more and 260 degrees C or less. The heating time is more preferably 5 minutes or more, even more preferably 8 minutes or more, and most preferably 10 minutes or more. A more preferable heating temperature is 245 ° C. or more and 255 ° C. or less, and may be 250 ° C. in particular. The heating time is, for example, 60 minutes or less, particularly 30 minutes or less. The heating time may be 10 minutes.

Alternatively, the heat treatment may be performed by heating at a temperature of 30 ° C. to 190 ° C. for 1 minute to 15 minutes and then heating at a temperature of 230 ° C. to 260 ° C. for 3 minutes or more. In the case where the heat treatment is performed in two stages, it is easy to obtain semiconductor nanoparticles having higher band edge emission intensity. In this case, the heating temperature in the first stage is more preferably 45 ° C. to 155 ° C., even more preferably 145 ° C. to 155 ° C., and particularly 150 ° C. The heating time of the first stage is more preferably 8 minutes or more and 13 minutes or less, still more preferably 9 minutes or more and 11 minutes or less, and particularly 10 minutes. The heating time of the second stage is more preferably 5 minutes or more, even more preferably 8 minutes or more, and most preferably 10 minutes or more. The heating temperature in the second stage is more preferably 245 ° C. or more and 255 ° C. or less, and particularly 250 ° C. The heating time of the second stage is, for example, 60 minutes or less, particularly 30 minutes or less. The heating time may be 10 minutes.
By carrying out the heat treatment in two stages, semiconductor nanoparticles having a relatively high band edge emission intensity can be produced with good reproducibility.

<Method for producing third semiconductor nanoparticles>
The semiconductor nanoparticles may be generated by a so-called hot injection method. In the hot injection method, a compound that is a source of each element (for example, a salt of Ag, a salt of In, and a compound that is a source of S) is supplied to a solvent heated to a temperature in the range of 100 ° C. to 300 ° C. This is a method for producing semiconductor nanoparticles in which a liquid (also referred to as a precursor solution) in which is dissolved or dispersed is introduced in a relatively short time (for example, on the order of milliseconds) to generate many crystal nuclei at the beginning of the reaction.

  Alternatively, in the hot injection method, a compound serving as a supply source of some elements may be dissolved or dispersed in an organic solvent in advance, and after heating this, a precursor solution of other elements may be added. . If the solvent is a surface modifier or a solvent containing a surface modifier, the surface modification can be performed simultaneously. The surface modifier is as described in relation to the first embodiment.

  Also in the hot injection method, the compound that is the source of each element that is finally added to the solvent has a ratio of the number of Ag atoms to the total number of Ag and In atoms (Ag / Ag + In) of 0.33 or more and 0 .42 or less is used. Further, it is preferable to use the compound serving as the supply source of S in such an amount that the ratio of the number of S atoms to the total number of Ag and In atoms (S / Ag + In) is 0.95 or more and 1.20 or less. . By using a compound serving as a supply source of each element so as to satisfy these conditions, it is possible to generate semiconductor nanoparticles that easily give band-end emission or have high intensity of band-end emission.

  Ag / Ag + In is more preferably 0.38 or more and 0.42 or less, and particularly 0.40. Further, S / Ag + In is more preferably 0.95 or more and 1.10 or less, and particularly 1.00.

  The method for producing semiconductor nanoparticles is not limited to the above. Any method may be used as long as the amount of the compound used as the supply source of each element is selected so that Ag / Ag + In is 0.33 or more and 0.42 or less.

  Regardless of which production method is employed, the semiconductor nanoparticles are produced in an inert atmosphere, particularly in an argon atmosphere or a nitrogen atmosphere. This is to reduce or prevent oxide by-product and semiconductor nanoparticle surface oxidation.

  In any production method, when the heat treatment is performed, the rate of temperature rise until reaching a predetermined heating temperature (for example, a temperature maintained for a certain period of time) may be, for example, 1 ° C./min to 50 ° C./min. Moreover, after heat processing, you may cool so that it may become predetermined | prescribed temperature, for example with the temperature-fall rate of 1 to 100 degree-C / min. Or you may implement the cooling after heat processing by leaving a heat source as off and cooling.

  In any production method, after the production of the semiconductor nanoparticles is completed, the obtained semiconductor nanoparticles may be separated from the organic solvent after the treatment, and further purified as necessary. Separation is performed, for example, by centrifuging an organic solvent containing nanoparticles after completion of production and taking out a supernatant liquid containing nanoparticles. Purification includes, for example, adding an organic solvent to the supernatant and centrifuging to remove the semiconductor nanoparticles as a precipitate. The precipitate may be removed itself or may be removed by removing the supernatant. The removed precipitate may be dried by, for example, vacuum degassing or natural drying, or a combination of vacuum degassing and natural drying. Natural drying may be carried out, for example, by leaving it in the atmosphere at room temperature and normal pressure. In that case, it may be left for 20 hours or longer, for example, about 30 hours.

  Alternatively, the removed precipitate may be dissolved in an organic solvent. Purification (addition of alcohol and centrifugation) may be performed multiple times as necessary. As alcohol used for purification, lower alcohols such as methanol, ethanol and n-propanol may be used. When the precipitate is dissolved in an organic solvent, chloroform, toluene, cyclohexane, hexane, pentane, octane, or the like may be used as the organic solvent.

In the semiconductor nanoparticles thus obtained, the ratio of the number of Ag atoms to the total number of Ag and In atoms is such that the Ag and In atoms in the salt of Ag and the salt of In introduced into the organic solvent. It tends to be obtained as smaller than the ratio of the number of Ag atoms to the total number. Therefore, according to the manufacturing method of the present embodiment, semiconductor nanoparticles containing Ag, In, and S, for example, the ratio of the number of Ag atoms to the total number of Ag and In atoms is 0.320 or more. Semiconductor nanoparticles having a ratio of the number of S atoms to the total number of Ag and In atoms of 1.20 or more and 1.45 or less can be produced. The semiconductor nanoparticles can emit light having a light emission lifetime of 200 ns or less when irradiated with light having a wavelength in the range of 350 to 500 nm.
Further, when the organic solvent contains the surface modifier itself or the surface modifier, semiconductor nanoparticles with a modified surface can be obtained.

(Third embodiment: core-shell type semiconductor nanoparticles)
As a third embodiment, a core-shell type semiconductor nanoparticle including a core and a shell that covers the surface of the core and heterojunction with the core will be described.
In the present embodiment, the core is the semiconductor nanoparticle described as the first embodiment. Therefore, detailed description thereof is omitted.

  The shell is a semiconductor substantially composed of a Group 13 element and a Group 16 element. The semiconductor constituting the shell may be a semiconductor having a larger band gap energy than the semiconductor constituting the core. Group 13 elements include B, Al, Ga, In, and Tl, and Group 16 elements include O, S, Se, Te, and Po.

  When the semiconductor nanoparticle (core) of the first embodiment is covered with a semiconductor (shell) substantially consisting of a group 13 element and a group 16 element, the ratio of band edge emission as compared to the case without the shell Can be further increased, and the ratio of light emission other than band edge light emission (particularly, defect light emission) can be further reduced. This is presumed to be because the surface defect site of the core disappears when the core is covered with the shell. In the present embodiment, when the shell has a larger band gap energy than the core, it is presumed that the band edge emission ratio is increased by forming an energy barrier.

The shell may include a combination of Ga and S as a combination of a Group 13 element and a Group 16 element. The combination of Ga and S is preferably used because the band gap energy is larger. The combination of Ga and S may be in the form of gallium sulfide. In this embodiment, the gallium sulfide constituting the shell does not have to be of stoichiometric composition (Ga ₂ S ₃ ). In this sense, gallium sulfide is expressed by the formula GaS _x (x is not limited to an integer) in this specification. It may be expressed by an arbitrary number, for example, 0.8 to 1.5).

  The shell may be amorphous. Whether or not an amorphous (amorphous) shell is formed can be confirmed by observing the core-shell type semiconductor nanoparticles of the present embodiment with HAADF-STEM. Specifically, a portion having a regular pattern (for example, a striped pattern or a dot pattern) is observed in the center, and a portion not observed as having a regular pattern around it is observed in the HAADF-STEM. Is done. According to HAADF-STEM, those having a regular structure such as a crystalline substance are observed as an image having a regular pattern, and those having no regular structure such as an amorphous substance are: It is not observed as an image having a regular pattern. Therefore, when the shell is amorphous, the shell is observed as a portion that is clearly different from the core (having a crystal structure such as tetragonal system as described above) that is observed as an image having a regular pattern. be able to.

  Further, when the core is made of Ag, In, and S and the shell is made of GaS, Ga is an element lighter than Ag and In. Therefore, in the image obtained by HAADF-STEM, the shell is darker than the core. Tend to be observed.

  The surface of the shell may be modified with any compound. If the surface of the shell is the exposed surface of the core-shell type semiconductor nanoparticles, the surface can be modified to stabilize the nanoparticles and prevent aggregation or growth of the semiconductor nanoparticles, and / or Dispersibility of the semiconductor nanoparticles in the solvent can be improved. Since the compounds applicable as the surface modifier are as described in the first embodiment, the description thereof is omitted here.

  The core-shell type semiconductor nanoparticles may have an average particle size of 50 nm or less, for example. The average particle diameter may be, for example, in the range of 1 nm to 20 nm, in particular in the range of 1 nm to 10 nm. The method for obtaining the particle diameter and the average particle diameter is as described in the first embodiment.

  In the core-shell type semiconductor nanoparticles, the core may have an average particle diameter of, for example, 10 nm or less, particularly 8 nm or less. The average particle size of the core may be in the range of 2 nm to 10 nm, in particular in the range of 2 nm to 8 nm, more particularly in the range of 2 nm to 6 nm, or in the range of 4 nm to 10 nm, 5 nm to 8 nm. When the average particle size of the core is too large, it is difficult to obtain the quantum size effect, and it becomes difficult to obtain band edge emission.

  The shell may have a thickness of 0.1 nm or more. The thickness of the shell may be in the range of 0.1 nm to 50 nm, in particular in the range of 0.1 nm to 20 nm, more particularly in the range of 0.2 nm to 10 nm. Alternatively, the thickness of the shell may be in the range of 0.1 nm to 3 nm, in particular in the range of 0.3 nm to 3 nm. When the thickness of the shell is too small, the effect of the shell covering the core is not sufficiently obtained, and it becomes difficult to obtain band edge light emission.

  The average particle diameter of the core and the thickness of the shell may be obtained by observing the core-shell type semiconductor nanoparticles with, for example, HAADF-STEM. In particular, when the shell is amorphous, the thickness of the shell that can be easily observed as a portion different from the core can be easily determined by HAADF-STEM. In that case, the particle size of the core can be determined according to the method described above for the semiconductor nanoparticles. If the shell thickness is not constant, the smallest thickness is taken as the shell thickness of the particle.

  Alternatively, the average particle diameter of the core may be measured in advance before coating with the shell. Then, the thickness of the shell may be determined by measuring the average particle size of the core-shell structured semiconductor nanoparticles and determining the difference between the average particle size and the previously measured average particle size of the core.

  The core-shell type semiconductor nanoparticles of the present embodiment are the semiconductor nanoparticles described in the first embodiment, and Ag / Ag + In and S / Ag + In are in a specific range in the core. Edge light emission can be emitted. Specifically, in an emission spectrum obtained when light having a wavelength in the range of 350 to 500 nm is irradiated, the peak wavelength is in the range of 550 nm to 650 nm, and the half width is 80 nm or less, particularly 50 nm or less. A certain emission peak is observed at 25 ° C. The lower limit of the full width at half maximum may be, for example, 20 nm, and particularly 10 nm.

  Moreover, the core-shell type semiconductor nanoparticle of this embodiment can emit the said band light emission in a big ratio because the said specific core is coat | covered with the said specific shell. Specifically, the core-shell type semiconductor nanoparticles of the present embodiment can give an emission spectrum such that the intensity of band edge emission normalized by the intensity of defect emission is, for example, 5 to 300, particularly 20 to 150. it can. The core-shell type semiconductor nanoparticles of this embodiment preferably do not emit light derived from defect emission.

  The emission lifetime of the band edge emission emitted by the core-shell type semiconductor nanoparticles of the present embodiment tends to be longer than that of the semiconductor nanoparticles not coated with the shell (that is, the semiconductor nanoparticles of the first embodiment). In some cases, it may exceed 200 ns. This is presumably because the relaxation process of non-radiative deactivation of the excited electrons is reduced due to the coating with the shell, and the lifetime of the excited electrons at the band edge level is increased. The core-shell nanoparticle of the present embodiment is considered to give band edge emission as long as the half-value width is 80 nm or less even if the emission lifetime exceeds 200 ns.

(Fourth embodiment: manufacturing method of core-shell type semiconductor nanoparticles)
Next, as a fourth embodiment, a method for producing the core-shell type semiconductor nanoparticles of the third embodiment will be described. The manufacturing method of the semiconductor nanoparticles as the core is as described in the second embodiment.

  When coating the core semiconductor nanoparticles (hereinafter referred to as “primary semiconductor nanoparticles” for the sake of convenience, the core before coating with the shell) with the shell, the dispersion is prepared by dispersing this in an appropriate solvent. Then, a semiconductor layer serving as a shell is formed in the dispersion. In the liquid in which the primary semiconductor nanoparticles are dispersed, since no scattered light is generated, the dispersion liquid is generally obtained as transparent (colored or colorless). The solvent in which the primary semiconductor nanoparticles are dispersed is not particularly limited, and may be any organic solvent (particularly a highly polar organic solvent such as ethanol) as in the case of producing the primary semiconductor nanoparticles. The organic solvent may be a surface modifier or a solution containing the surface modifier. For example, the organic solvent may be at least one selected from nitrogen-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms, or selected from sulfur-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms. At least one, or at least one selected from nitrogen-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms and at least one selected from sulfur-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms It may be a combination. Specific organic solvents include oleylamine, n-tetradecylamine, dodecanethiol, or combinations thereof.

  The dispersion of primary semiconductor nanoparticles may be prepared such that the ratio of the particles in the dispersion is, for example, 0.02% by mass to 1% by mass, particularly 0.1% by mass to 0.6% by mass. . If the proportion of particles in the dispersion is too small, it becomes difficult to recover the product by the coagulation / precipitation process with a poor solvent. If the proportion is too large, the Ostwald ripening of the material constituting the core, the proportion of fusion due to collision increases, The diameter distribution tends to be wide.

The semiconductor layer to be the shell is formed by adding a compound containing a Group 13 element and a group 16 element alone or a compound containing a Group 16 element to the dispersion.
A compound containing a Group 13 element serves as a Group 13 element source, and examples thereof include organic salts, inorganic salts, and organometallic compounds of Group 13 elements. Specifically, examples of the compound containing a Group 13 element include nitrates, acetates, sulfates, hydrochlorides, sulfonates, and acetylacetonato complexes, preferably organic salts such as acetates, or organic metals. A compound. This is because organic salts and organometallic compounds have high solubility in organic solvents, and the reaction is more likely to proceed more uniformly.

  A single group 16 element or a compound containing a group 16 element is a group 16 element source. For example, when sulfur (S) is used as a constituent element of the shell as a group 16 element, a simple sulfur such as high-purity sulfur can be used, or n-butanethiol, isobutanethiol, n-pentanethiol , N-hexanethiol, octanethiol, decanethiol, dodecanethiol, hexadecanethiol, octadecanethiol and other thiols, disulfide such as dibenzylsulfide, sulfur-containing compounds such as thiourea and thiocarbonyl compounds can be used.

  When oxygen (O) is used as a constituent element of the shell as the Group 16 element, alcohol, ether, carboxylic acid, ketone, or N oxide compound may be used as the Group 16 element source. When selenium (Se) is used as a constituent element of the shell as a group 16 element, selenium alone, selenide phosphine oxide, organic selenium compound (dibenzyl diselenide or diphenyl diselenide), hydride, etc. A compound may be used as a Group 16 element source. When tellurium (Te) is used as a constituent element of the shell as the Group 16 element, tellurium alone, tellurium phosphine oxide, or hydride may be used as the Group 16 element source.

  The method for adding the group 13 element source and the group 16 element source to the dispersion is not particularly limited. For example, a mixed solution in which a group 13 element source and a group 16 element source are dispersed or dissolved in an organic solvent is prepared, and this mixed solution may be added to the dispersion little by little, for example, by dropping. In this case, the mixture may be added at a rate of 0.1 mL / hour to 10 mL / hour, in particular 1 mL / hour to 5 mL / hour. Moreover, you may add a liquid mixture to the heated dispersion liquid. Specifically, for example, the temperature of the dispersion is raised so that the peak temperature becomes 200 ° C. to 300 ° C., and after reaching the peak temperature, the mixture is added little by little while maintaining the peak temperature. Thereafter, the shell layer may be formed by a method of lowering the temperature (slow injection method). The peak temperature may be maintained as necessary even after the addition of the mixed solution is completed.

  If the peak temperature is too low, the surface modifier that modifies the primary semiconductor nanoparticles will not be sufficiently removed, or the chemical reaction for shell formation will not proceed sufficiently. May be insufficiently formed. If the peak temperature is too high, the primary semiconductor nanoparticles may be altered, and band edge emission may not be obtained even if a shell is formed. The time for maintaining the peak temperature may be 1 minute to 300 minutes in total from the start of the addition of the mixed solution, particularly 10 minutes to 60 minutes. The retention time of the peak temperature is selected in relation to the peak temperature, with a longer retention time when the peak temperature is lower and a shorter retention time when the peak temperature is higher, a good shell layer Is easily formed. The temperature increase rate and the temperature decrease rate are not particularly limited, and the temperature decrease may be performed by, for example, holding the peak temperature for a predetermined time and then allowing the heating source (for example, an electric heater) to be turned off and allowing to cool.

  Alternatively, the group 13 element source and the group 16 element source may be added directly to the dispersion directly. Then, the semiconductor layer as a shell may be formed on the surface of the primary semiconductor nanoparticles by heating the dispersion liquid to which the Group 13 element source and Group 16 element source are added (heating up method). Specifically, the dispersion added with the group 13 element source and the group 16 element source is gradually heated, for example, so that the peak temperature becomes 200 ° C. to 300 ° C., and the peak temperature is 1 After holding for 300 minutes, the heat may be gradually lowered. The rate of temperature increase may be, for example, 1 ° C./min to 50 ° C./min, and the rate of temperature decrease may be, for example, 1 ° C./min to 100 ° C./min. Alternatively, the temperature may be heated to a predetermined peak temperature without particularly controlling the temperature rising rate, or the temperature may be lowered at a constant rate, and the heating source may be turned off and allowed to cool. Good. The problem when the peak temperature is too low or too high is as described in the method of adding the above mixed solution.

  According to the heating-up method, core-shell type semiconductor nanoparticles that give stronger band edge emission tend to be obtained as compared with the case where the shell is formed by the slow injection method.

Regardless of which method is used to add the Group 13 element source and the Group 16 element source, the charging ratio of both corresponds to the stoichiometric composition ratio of the compound semiconductor composed of the Group 13 element and the Group 16 element. It is preferable. For example, when a Ga source is used as the Group 13 element source and an S source is used as the Group 16 element source, the charging ratio is 1: 1.5 (Ga: S) corresponding to the composition formula of Ga ₂ S _3. ) Is preferable. However, the charging ratio does not necessarily have to be the stoichiometric composition ratio. When the raw material is charged in an excess amount than the target shell generation amount, for example, the group 16 element source is determined from the stoichiometric composition ratio. For example, the charging ratio may be 1: 1 (Group 13: Group 16).

Further, the preparation amount is selected in consideration of the amount of primary semiconductor nanoparticles contained in the dispersion so that a shell having a desired thickness is formed on the primary semiconductor nanoparticles present in the dispersion. For example, a compound semiconductor having a stoichiometric composition composed of a group 13 element and a group 16 element is generated in an amount of 0.01 mmol to 10 mmol, particularly 0.1 mmol to 1 mmol, with respect to 10 nmol of the substance amount as particles of the primary semiconductor nanoparticles. As described above, the charged amounts of the Group 13 element source and the Group 16 element source may be determined. However, the substance amount as a particle is a molar amount when one particle is regarded as a huge molecule, and the number of nanoparticles contained in the dispersion is expressed by the Avogadro number (N _A = 6.022 × Equal to the value divided by 10 ²³ ).

  When the shell is formed by the heating-up method, if the holding time is increased (for example, 40 minutes or more, particularly 50 minutes or more, the upper limit is, for example, 60 minutes or less), the band edge emission is strong and the band edge emission ratio is large. Core-shell type semiconductor nanoparticles (having a large band edge emission / defect emission intensity ratio) are easily obtained. However, if the holding time is too long, the intensity of the band edge emission tends to decrease, and in some cases, light emission may be hardly obtained. Further, as the holding time is increased, the peak of band-end emission emitted from the obtained semiconductor nanoparticles tends to shift to the short wavelength side, and the half-value width of band-end emission tends to increase.

  In this way, a shell is formed to form core-shell type semiconductor nanoparticles. The obtained core-shell semiconductor nanoparticles may be separated from the solvent, and may be further purified and dried as necessary. The separation, purification, and drying methods are as described in the second embodiment, and thus detailed description thereof is omitted here.

(Light emitting device)
Next, as another embodiment according to the present invention, the semiconductor nanoparticles described above, that is, the semiconductor nanoparticles of the first embodiment, the method of the second embodiment (first to third semiconductor nanoparticles) The core-shell type semiconductor nanoparticles manufactured by the method of the fourth embodiment, or the core-shell type semiconductor nanoparticles manufactured by the method of the fourth embodiment (hereinafter collectively referred to as these) A light-emitting device using “semiconductor nanoparticles of the present disclosure” or “nanoparticles of the present disclosure”) will be described.
The light-emitting device which is embodiment of this invention is a light-emitting device containing a light conversion member and a semiconductor light-emitting element, Comprising: The semiconductor nanoparticle of this indication is included in a light conversion member. According to this light emitting device, for example, a part of the light emitted from the semiconductor light emitting element is absorbed by the semiconductor nanoparticles of the present disclosure, and light having a longer wavelength is emitted. And the light from the semiconductor nanoparticle of this indication and the remainder of light emission from a semiconductor light emitting element are mixed, and the mixed light can be utilized as light emission of a light emitting device.

Specifically, a semiconductor light emitting element that emits blue-violet light or blue light having a peak wavelength of about 400 nm to 490 nm is used, and semiconductor nanoparticles of the present disclosure absorb blue light and emit yellow light (for example, If the average particle diameter of the semiconductor nanoparticles in the first embodiment is in the range of 4.0 to 5.0 nm, a light emitting device that emits white light can be obtained. Alternatively, as the semiconductor nanoparticles of the present disclosure, a white light emitting device can be obtained by using two types of semiconductor nanoparticles that absorb blue light and emit green light and those that absorb blue light and emit red light. it can.
Alternatively, using a semiconductor light emitting device that emits ultraviolet light having a peak wavelength of 400 nm or less, and absorbing three ultraviolet rays to emit blue light, green light, and red light, respectively, and using three types of semiconductor nanoparticles of the present disclosure, A white light emitting device can be obtained. In this case, it is desirable that all the light from the light emitting element is absorbed and converted by the semiconductor nanoparticles of the present disclosure so that ultraviolet rays emitted from the light emitting element do not leak to the outside.

Alternatively, when emitting blue-green light having a peak wavelength of about 490 nm to 510 nm and using the semiconductor nanoparticles that absorb blue-green light and emit red light as the semiconductor nanoparticles of the present disclosure, white light is emitted. You can get a device.
Alternatively, if a semiconductor light emitting device that emits red light having a wavelength of 700 nm to 780 nm is used, and a semiconductor nanoparticle of the present disclosure that absorbs red light and emits near infrared light, the near infrared light is emitted. A light emitting device can also be obtained.

The semiconductor nanoparticles of the present disclosure may be used in combination with other semiconductor quantum dots, or may be used in combination with phosphors that are not other quantum dots (for example, organic phosphors or inorganic phosphors). The other semiconductor quantum dots are, for example, the binary semiconductor quantum dots described in the background art section. As a phosphor that is not a quantum dot, a garnet phosphor such as an aluminum garnet can be used. Examples of garnet phosphors include yttrium / aluminum / garnet phosphors activated with cerium and lutetium / aluminum / garnet phosphors activated with cerium. Nitrogen-containing calcium aluminosilicate phosphors activated with europium and / or chromium, silicate phosphors activated with europium, β-SiAlON phosphors, nitride phosphors such as CASN or SCASN, Rare earth nitride phosphors such as LnSi ₃ N11 or LnSiAlON, BaSi ₂ O ₂ N ₂ : Eu or Ba ₃ Si ₆ O ₁₂ N ₂ : Eu oxynitride phosphors such as CaS, SrGa ₂ S ₄ -based, SrAl ₂ O ₄ -based, ZnS-based sulfide phosphors, chlorosilicate phosphors, SrLiAl ₃ N ₄ : Eu phosphors, SrMg ₃ SiN ₄ : Eu phosphors, activated with manganese A K ₂ SiF ₆ : Mn phosphor or the like as the fluoride complex phosphor can be used.

  In the light emitting device, the light conversion member including the semiconductor nanoparticles of the present disclosure may be, for example, a sheet or a plate-like member, or may be a member having a three-dimensional shape. An example of a member having a three-dimensional shape is a surface-mounted light emitting diode, in which a semiconductor light emitting element is disposed on the bottom surface of a concave portion formed in a package, and the concave portion is used to seal the light emitting element. It is a sealing member formed by filling a resin.

Alternatively, another example of the light conversion member is a resin formed so as to surround the upper surface and the side surface of the semiconductor light emitting element with a substantially uniform thickness when the semiconductor light emitting element is disposed on a flat substrate. It is a member.
Alternatively, still another example of the light conversion member is a case where a resin member including a reflective material is filled around the semiconductor light emitting element so that the upper end of the semiconductor light emitting element is flush with the semiconductor light emitting element. It is a resin member formed in a flat plate shape with a predetermined thickness on the upper part of the resin member including the semiconductor light emitting element and the reflector.

The light conversion member may be in contact with the semiconductor light emitting element or may be provided apart from the semiconductor light emitting element. Specifically, the light conversion member may be a pellet-shaped member, a sheet member, a plate-shaped member, or a rod-shaped member disposed away from the semiconductor light-emitting element, or a member provided in contact with the semiconductor light-emitting element, for example, , A sealing member, a coating member (a member that covers a light emitting element provided separately from the mold member), or a mold member (for example, a member having a lens shape).
In addition, in the light emitting device, when two or more types of semiconductor nanoparticles of the present disclosure that emit light of different wavelengths are used, the two or more types of semiconductor nanoparticles of the present disclosure are mixed in one light conversion member. Alternatively, two or more light conversion members including only one type of quantum dot may be used in combination. In this case, the two or more types of light conversion members may have a laminated structure, or may be arranged as a dot or stripe pattern on a plane.

An LED chip is mentioned as a semiconductor light emitting element. The LED chip may include one or more semiconductor layers selected from the group consisting of GaN, GaAs, InGaN, AlInGaP, GaP, SiC, ZnO, and the like. Violet light, the semiconductor light emitting element which emits blue light, or ultraviolet light, is preferably represented in the general formula _{In X Al Y Ga 1-X} -Y N (0 ≦ X, 0 ≦ Y, X + Y <1) It is preferable that a GaN-based compound is provided as a semiconductor layer.

The light emitting device of this embodiment is preferably incorporated in a liquid crystal display device as a light source. Since the band edge emission by the semiconductor nanoparticles of the present disclosure has a short emission lifetime, a light emitting device using this is suitable as a light source for a liquid crystal display device that requires a relatively fast response speed. In addition, the semiconductor nanoparticles of the present disclosure can exhibit an emission peak with a small half width as band edge emission. Thus, in a light emitting device:
-Blue light having a peak wavelength in the range of 420 nm to 490 nm is obtained by the blue semiconductor light emitting device, and green having a peak wavelength in the range of 510 nm to 550 nm, preferably 530 nm to 540 nm, by the semiconductor nanoparticles of the present disclosure. To obtain light and red light with a peak wavelength in the range of 600 nm to 680 nm, preferably 630 to 650 nm; or
-In a light-emitting device, ultraviolet light having a peak wavelength of 400 nm or less is obtained by a semiconductor light-emitting element, and blue light having a peak wavelength in the range of 430 to 470 nm, preferably 440 to 460 nm, preferably having a peak wavelength by the semiconductor nanoparticles of the present disclosure. By obtaining green light of 510 nm to 550 nm, preferably 530 to 540 nm, and red light having a peak wavelength in the range of 600 to 680 nm, preferably 630 to 650 nm, the color can be obtained without using a dark color filter. A liquid crystal display device with good reproducibility can be obtained. The light emitting device of the present embodiment is used as, for example, a direct type backlight or an edge type backlight.

  Or the sheet | seat, plate-shaped member, or rod which consists of resin or glass etc. containing the semiconductor nanoparticle of this indication may be integrated in the liquid crystal display device as a light conversion member independent of the light emitting device.

(Examples 1-3)
0.10 mmol of silver acetate (AgOAc), 0.15 mmol of indium acetate (In (OAc) ₃ ), and 0.25 mmol of thiourea were added to 0.10 cm ³ of 1-dodecanethiol and 2.90 cm ³ of oleylamine. It poured into the liquid mixture and disperse | distributed. Regarding silver acetate and indium acetate, Ag / Ag + In was 0.4 in all examples. The dispersion was placed in a test tube together with a stirrer and replaced with nitrogen, and then heat treatment was performed under the conditions shown in Table 1 while stirring the contents in the test tube in a nitrogen atmosphere.

  All heat treatments were performed at a predetermined temperature for 10 minutes. After the heat treatment, the resulting suspension was allowed to cool and then centrifuged (radius 146 mm, 4000 rpm, 5 minutes) to take out the supernatant solution. Methanol was added thereto until precipitation of the nanoparticles, and centrifugation (radius 146 mm, 4000 rpm, 5 minutes) was performed to precipitate the nanoparticles. The precipitate was taken out and dissolved in chloroform, and the following measurement was performed.

The XRD pattern of the semiconductor nanoparticles obtained in Example 2 was measured and compared with tetragonal (chalcopyrite type) AgInS ₂ and orthorhombic AgInS ₂ . The measured XRD pattern is shown in FIG. From the XRD pattern, it was found that the crystal structure of the semiconductor nanoparticles of Example 2 was almost the same as that of tetragonal AgInS ₂ . The XRD pattern was measured using a powder X-ray diffractometer (trade name SmartLab) manufactured by Rigaku (same in the following experimental examples).

  Moreover, while observing the shape of the obtained semiconductor nanoparticle using a transmission electron microscope (TEM, Hitachi High-Technologies Corporation make, brand name H-7650), the average particle diameter is 80,000 to 200,000 times. It measured from the TEM image of. Here, a commercially available copper grid with an elastic carbon support film (Oken Corporation) was used as the TEM grid. The shape of the obtained particles was spherical or polygonal.

The average particle size is the particle size for all the nanoparticles included in the TEM image except for those that can be measured, i.e., all particles that have a broken image at the edge of the image. The measurement was performed and the arithmetic average was obtained. When the number of nanoparticles contained in one TEM image is less than 100, another TEM image is measured, the particle size of the particles contained in the TEM image is measured, and the arithmetic average is 100 or more particles. I asked for it.
The average particle size of the semiconductor nanoparticles of each example was as follows.
Example 1: 4.1 nm
Example 2: 4.6 nm
Example 3: 5.1 nm

Next, for the obtained semiconductor nanoparticles, when the total number of Ag, In and S atoms contained in the semiconductor nanoparticles is set to 100 using an energy dispersive X-ray analyzer (Horiba, EMAX Energy) Then, the ratio of each atom was determined. The results are shown in Table 1.
Specifically, the measurement using the energy dispersive X-ray analyzer was performed according to the following procedure (the same applies to the following experimental examples).
The prepared nanoparticle dispersion solution was dropped on a carbon tape fixed to a sample stage and dried. From the spectrum observed with the energy dispersive X-ray analyzer, each component was quantified based on the intensity of the signal using signals derived from Ag, In, and S. Five points were measured while changing the measurement location, and the average value was taken as the result.

Absorption and emission spectra were measured for the semiconductor nanoparticles obtained in Examples 1 to 3. The results are shown in FIG. 2 (absorption spectrum, Example 1: solid line, Example 2: one-dot chain line, Example 3: dotted line) and FIG. 3 (emission spectrum, Example 1: solid line, Example 2: one-dot chain line, Example). 3: Dotted line) The absorption spectrum was measured using a diode array type spectrophotometer (manufactured by Agilent Technologies, trade name Agilent 8453A) at a wavelength of 190 nm to 1100 nm. The emission spectrum was measured at an excitation wavelength of 365 nm using a multichannel spectrometer (trade name PMA11, manufactured by Hamamatsu Photonics). The wavelength and half width of the steep emission peak observed in the emission spectrum of each example are as follows.
Example 1: Around 590 nm, full width at half maximum 42 nm
Example 2: Near 590 nm, half-value width 50 nm
Example 3: Near 590 nm, half width 55 nm

The emission lifetime is measured by using a fluorescence lifetime measuring apparatus (trade name: Quantaurus-Tau) manufactured by Hamamatsu Photonics Co., Ltd., by irradiating the obtained semiconductor nanoparticles with light having a wavelength of 470 nm as excitation light. Light having different wavelengths was emitted, and an emission attenuation curve near the peak wavelength of the steep emission peak was obtained. The obtained attenuation curve was divided into three components by parameter fitting using fluorescence lifetime measurement / analysis software U11487-01 manufactured by Hamamatsu Photonics Co., Ltd. As a result, τ ₁ , τ ₂ , and τ ₃ and the contribution ratios (A ₁ , A _2, and A ₃ ) of each component are as shown in Table 3 below.

The emission lifetime (τ2: 25.9 ns) of the main component of Example 2 is comparable to the lifetime (30 to 60 ns) of CdSe nanoparticles in which band edge emission is confirmed, and this emission is due to the band edge. I found out.
In Example 1, the intensity of the band edge emission was lower than the intensity of other emission (including defect emission) observed on the longer wavelength side than the band edge emission. This is considered to be due to the fact that in Example 1, the temperature of the first stage heat treatment was lower than that in Example 2.
In the absorption spectra of Examples 2 and 3, an exciton peak was observed around 550 nm.

(Example 4, Comparative Examples 1 and 2)
Silver acetate (AgOAc) and indium acetate (In (OAc) ₃ ), Ag / Ag + In becomes 0.3 (Comparative Example 1), 0.4 (Example 4), and 0.5 (Comparative Example 2), respectively. And the total amount of the two metal salts was measured to be 0.25 mmol. Silver acetate (AgOAc), indium acetate (In (OAc) ₃ ), and 0.25 mmol of thiourea are charged into a mixture of 0.10 cm ³ of oleylamine and 2.90 cm ³ of 1-dodecanethiol and dispersed. It was. About silver acetate and indium acetate, after putting a dispersion liquid into a test tube with a stirring bar and performing nitrogen substitution, it heated at 150 degreeC for 10 minutes, stirring the contents in a test tube in nitrogen atmosphere ( First stage heat treatment) and further heated at 250 ° C. for 10 minutes (second stage heat treatment).

After the heat treatment, the obtained suspension was allowed to cool and then centrifuged (radius 146 mm, 4000 rpm, 5 minutes).
For Comparative Example 1, after washing the precipitate with methanol, chloroform was added to the precipitate and subjected to centrifugation (radius 146 mm, 4000 rpm, 15 minutes), the supernatant was collected, and the following measurements were performed.
For Example 4 and Comparative Example 2, the supernatant solution was taken out. Methanol was added thereto until precipitation of the nanoparticles, and centrifugation (radius 146 mm, 4000 rpm, 5 minutes) was performed to precipitate the nanoparticles. The precipitate was taken out and dissolved in chloroform, and the following measurement was performed.
In addition, although Example 4 was manufactured on the same conditions as Example 2, since it manufactured separately from Example 2, in average particle diameter etc., it is a little different from Example 2. FIG.

  Moreover, while observing the shape of the obtained semiconductor nanoparticles, the average particle size was measured. The shape of the obtained particles was spherical or polygonal. The average particle size of Comparative Example 1 was 10.4 nm, the average particle size of Example 4 was 4.3 nm, and the average particle size of Comparative Example 2 was 3.8 nm.

  Next, with respect to the obtained semiconductor nanoparticles, when the total number of atoms of Ag, In and S contained in the semiconductor nanoparticles is set to 100 using a fluorescent X-ray analyzer (trade name EDXL300, manufactured by Rigaku Corporation) Then, the ratio of each atom was determined. The results are shown in Table 4.

  The absorption and emission spectra of the semiconductor nanoparticles obtained in Comparative Examples 1 and 2 and Example 4 were measured. The results are shown in FIG. 4 (absorption spectrum, Example 4: solid line, comparative example 1: dotted line, comparative example 2: one-dot chain line) and FIG. 5 (emission spectrum, Example 4: solid line, comparative example 1: dotted line, comparative example 2). : One-dot chain line). The absorption spectrum and emission spectrum were measured using the apparatus and method described in Examples 1-3.

As shown in FIG. 5, in the emission spectra of Comparative Examples 1 and 2, although a small peak was observed around a wavelength of 580 nm corresponding to the peak wavelength of the band edge emission in Example 4, the intensity was extremely small. .
In the absorption spectrum of Comparative Example 1, an exciton peak was observed near 570 nm, and in the absorption spectrum of Comparative Example 2, an exciton peak was observed near 530 nm.

(Example 5)
<1> Production of Core (Primary Semiconductor Nanoparticles) Silver acetate (AgOAc) and indium acetate (In (OAc) ₃ ) have an Ag / Ag + In of 0.4, and the total amount of the two metal salts is 0.00. Weighed out to 25 mmol. Silver acetate (AgOAc), indium acetate (In (OAc) ₃ ), and 0.25 mmol of thiourea are charged into a mixture of 0.10 cm ³ of oleylamine and 2.90 cm ³ of 1-dodecanethiol and dispersed. It was. About silver acetate and indium acetate, after putting a dispersion liquid into a test tube with a stirring bar and performing nitrogen substitution, it heated at 150 degreeC for 10 minutes, stirring the contents in a test tube in nitrogen atmosphere ( First stage heat treatment) and further heated at 250 ° C. for 10 minutes (second stage heat treatment).

  After the heat treatment, the obtained suspension was allowed to cool and then centrifuged (radius 146 mm, 4000 rpm, 5 minutes). Thereafter, the supernatant solution was taken out. Methanol was added thereto until precipitation of the nanoparticles, and centrifugation (radius 146 mm, 4000 rpm, 5 minutes) was performed to precipitate the nanoparticles. Ethanol was added to the precipitate and stirred, and then centrifuged again (radius 146 mm, 4000 rpm, 5 minutes) to precipitate the nanoparticles. The precipitate was taken out and dissolved in chloroform, and the following measurement was performed.

  While observing the shape of the obtained semiconductor nanoparticles, the average particle size was measured. The shape of the obtained particles was spherical or polygonal. The average particle size was 4.6 nm.

  Next, with respect to the obtained semiconductor nanoparticles, when the total number of atoms of Ag, In and S contained in the semiconductor nanoparticles is set to 100 using a fluorescent X-ray analyzer (trade name EDXL300, manufactured by Rigaku Corporation) Then, the ratio of each atom was determined. The results are shown in Table 5.

  Absorption and emission spectra were measured for the obtained semiconductor nanoparticles. The methods for measuring the absorption spectrum and the emission spectrum are the same as those in Examples 1 to 3. The result is shown in FIG. As shown in FIG. 6, in the emission spectrum of the semiconductor nanoparticles, a steep emission peak with a half-width of 50 nm having a peak wavelength around 580 nm is observed, and a broad emission with a peak wavelength around 705 nm. A peak was observed.

  The light emission lifetime was measured by the same method as used in Example 2. The results are shown in Table 6.

  The emission lifetime (τ2: 39.3 ns) of the main component of the semiconductor nanoparticles is comparable to the lifetime (30 to 60 ns) of CdSe nanoparticles that have been confirmed to emit band edges. I found out that

<2> Production of core-shell type semiconductor nanoparticles (formation of shell)
The semiconductor nanoparticles produced in the above <1> were used as cores (primary semiconductor nanoparticles), and a shell was formed on the surface thereof.
Specifically, among the primary semiconductor nanoparticles prepared in <1>, 1.0 × 10 ⁻⁵ mmol (10 nmol) as a nanoparticle and a gallium acetylacetonate (Ga (acac) ₃ ) 5 and .33 × 10 ^-5 mmol, thiourea 5.33 × 10 ^-5 mmol, and oleylamine 2.9 cm ^3, and 1-dodecanethiol 0.1 cm ^3, placed in a test tube, 60 at 300 ° C. After holding for a minute, the heating source was turned off and the mixture was allowed to cool. Thereafter, the mixture was centrifuged (radius 146 mm, 4000 rpm, 5 minutes) to precipitate the nanoparticles. The supernatant was discarded, methanol was added to the precipitate and stirred, and then centrifuged again (radius 146 mm, 4000 rpm, 5 minutes) to precipitate the nanoparticles. The precipitate was taken out, ethanol was added, and the mixture was stirred and centrifuged again (radius 146 mm, 4000 rpm, 5 minutes) to precipitate the nanoparticles. The precipitate was taken out and dissolved in chloroform, and the following measurement was performed.

  While observing the shape of the obtained core-shell type semiconductor nanoparticles, the average particle size was measured. The shape of the obtained particles was spherical or polygonal. The average particle size was 6.5 nm. From the difference between the average particle size and the previously measured average particle size of the core, the average thickness of the shell was about 0.95 nm.

  The obtained core-shell type semiconductor nanoparticles were measured for absorption and emission spectra. The methods for measuring the absorption spectrum and the emission spectrum are the same as those in Examples 1 to 3. The result is shown in FIG. As shown in FIG. 7, in the emission spectrum of the semiconductor nanoparticles, a steep emission peak (band edge emission) with a half-value width of 49 nm having a peak wavelength near 580 nm was observed. Further, the intensity of the broad emission peak (defect emission) having a wavelength around 710 nm was extremely small. The band edge emission intensity normalized by the defect emission intensity was 18. From this result, it was found that coating with a specific shell is effective for increasing the ratio of band edge emission.

  The light emission lifetime was measured by the same method as used in Example 2. The results are shown in Table 7.

  It was confirmed that the emission lifetime (τ3: 248 ns) of the main component of the core-shell type semiconductor nanoparticles is longer than that of the core. In addition, a component (τ2, A2) having an emission lifetime of 51.9 ns was observed with the same intensity as the main component. This emission lifetime is the same as the fluorescence lifetime (30 ns to 60 ns) of the component having the largest contribution ratio with the fluorescence emitted by CdSe (nanoparticles) whose band edge emission is confirmed.

  The obtained core-shell type semiconductor nanoparticles were observed with HAADF-STEM (manufactured by JEOL, trade name JEM-ARM200F Cold). A HAADF image is shown in FIG. In the HAADF image, a crystalline core having a regular pattern and a shell not having a regular pattern located around the crystalline core were observed, and the shell was observed to be amorphous in this particle.

  For comparison, FIG. 9 shows a HAADF image of the semiconductor nanoparticles (core) obtained in <1>. In the HAADF image shown in FIG. 9, only crystalline particles having a regular pattern were observed, and no region having a regular pattern was observed in the periphery thereof.

  About the obtained core-shell type semiconductor nanoparticles, in the HAADF image, a central region observed as a crystalline core having a regular pattern and a peripheral region observed as a shell having no regular pattern The atomic percentages of S (sulfur) and Ga (gallium) contained were analyzed by an energy dispersive X-ray analysis (EDS) apparatus (trade name EMAX Energy, manufactured by Horiba, Ltd.). The atomic percentage of S and Ga is a ratio when the total number of Ag, In, Ga and S atoms is 100%. The analysis results are shown in Table 8.

As shown in Table 8, more Ga and S were detected at the periphery than at the center. From this result, it was confirmed that the obtained particles had a core-shell structure in which GaS _x was segregated on the surface of the particles from the point of elemental composition.

  The embodiment according to the present invention is a semiconductor nanoparticle capable of emitting a band edge, and can be used as a wavelength conversion substance of a light emitting device or as a biomolecule marker.

<Method for generating second semiconductor nanoparticles>
The semiconductor nanoparticles may be produced by a method in which an Ag salt, an In salt, and a compound serving as a source of S are added to an organic solvent at a time, and then the organic solvent is heated. According to this method, it can be synthesized reproducibly nanoparticles Wanpo' up by a simple operation.
Alternatively, the organic solvent is reacted with an Ag salt to form a complex, and then the organic solvent is reacted with an In salt to form a complex. And the resulting reaction product may be produced by crystal growth. In this case, the heating is carried out at the stage of reacting with the compound serving as the supply source of S.
The salt of Ag and the salt of In are as described in relation to the production method (formation method of the first semiconductor nanoparticles) including the formation of the complex.

Moreover, the core-shell type semiconductor nanoparticles of the present embodiment can emit the band edge emission at a large rate by covering the specific core with the specific shell. Specifically, the core-shell type semiconductor nanoparticles of the present embodiment can give an emission spectrum such that the intensity of band edge emission normalized by the intensity of defect emission is, for example, 5 to 300, particularly 20 to 150. it can. The core-shell type semiconductor nanoparticles of this embodiment preferably do not emit light derived from defect emission.

When the core semiconductor nanoparticles (hereinafter referred to as “primary semiconductor nanoparticles” for the sake of convenience) are coated with a shell, a dispersion in which this is dispersed in an appropriate solvent is prepared. It was manufactured, to form a semiconductor layer made of a shell in the dispersion. In the liquid in which the primary semiconductor nanoparticles are dispersed, since no scattered light is generated, the dispersion liquid is generally obtained as transparent (colored or colorless). The solvent in which the primary semiconductor nanoparticles are dispersed is not particularly limited, and may be any organic solvent (particularly a highly polar organic solvent such as ethanol) as in the case of producing the primary semiconductor nanoparticles. The organic solvent may be a surface modifier or a solution containing the surface modifier. For example, the organic solvent may be at least one selected from nitrogen-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms, or selected from sulfur-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms. At least one, or at least one selected from nitrogen-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms and at least one selected from sulfur-containing compounds having a hydrocarbon group having 4 to 20 carbon atoms It may be a combination. Specific organic solvents include oleylamine, n-tetradecylamine, dodecanethiol, or combinations thereof.

A single group 16 element or a compound containing a group 16 element is a group 16 element source. For example, when sulfur (S) is used as a constituent element of the shell as a group 16 element, a simple sulfur such as high-purity sulfur can be used, or n-butanethiol, isobutanethiol, n-pentanethiol , n- hexane thiol, octane thiol, decane thiol, dodecane thiol, hexadecane thiol, thiol such as octadecane thiol, can be used disulfides such as dibenzyl disulfide, thiourea, sulfur containing compounds such as thiocarbonyl compound.

Next, for the obtained semiconductor nanoparticles, when the total number of Ag, In and S atoms contained in the semiconductor nanoparticles is set to 100 using an energy dispersive X-ray analyzer (Horiba, EMAX Energy) Then, the ratio of each atom was determined. The results are shown in Table 2 .
Specifically, the measurement using the energy dispersive X-ray analyzer was performed according to the following procedure (the same applies to the following experimental examples).
The prepared nanoparticle dispersion solution was dropped on a carbon tape fixed to a sample stage and dried. From the spectrum observed with the energy dispersive X-ray analyzer, each component was quantified based on the intensity of the signal using signals derived from Ag, In, and S. Five points were measured while changing the measurement location, and the average value was taken as the result.

Claims (15)

A method for producing semiconductor nanoparticles by reacting an Ag salt, an In salt, and a compound serving as a source of S in an organic solvent,
(A) preparing an Ag salt, an In salt, a compound serving as a source of S, and an organic solvent;
(B) the Ag salt, the In salt, and the S source so that the ratio of the number of Ag atoms to the total number of Ag and In atoms is 0.33 or more and 0.42 or less; A compound to be formed in the organic solvent to produce semiconductor nanoparticles,
The manufacturing method of the semiconductor nanoparticle containing this.   In (b), the organic solvent containing the Ag salt, the In salt, and the compound serving as the source of S is heated at a temperature of 230 ° C. to 260 ° C. for 3 minutes or more. The method for producing semiconductor nanoparticles according to claim 1, further comprising producing semiconductor nanoparticles. In the above (b), the organic solvent containing the Ag salt, the In salt, and the compound serving as the source of S is heated at a temperature of 30 ° C. to 190 ° C. for 1 minute to 15 minutes. After heating
The method for producing semiconductor nanoparticles according to claim 1, further comprising producing semiconductor nanoparticles by heating at a temperature of 230 ° C or higher and 260 ° C or lower for 3 minutes or more.   In (b), the compound serving as the supply source of S is added to the organic solvent so that the ratio of the number of S atoms to the total number of Ag and In atoms is 0.95 or more and 1.20 or less. The manufacturing method of the semiconductor nanoparticle of any one of Claims 1-3 to introduce | transduce.   In the generated semiconductor nanoparticles, the ratio of the number of Ag atoms to the total number of Ag and In atoms is such that the Ag salt and the In salt added to the organic solvent are Ag and In. The manufacturing method of the semiconductor nanoparticle of any one of Claims 1-4 smaller than the ratio of the number of Ag atoms with respect to the sum total of the number of atoms.   The organic solvent includes at least one solvent selected from thiols having a hydrocarbon group having 4 to 20 carbon atoms and at least one solvent selected from amines having a hydrocarbon group having 4 to 20 carbon atoms. The method for producing semiconductor nanoparticles according to any one of claims 1 to 5, which is a mixed solvent. (C) After the step (b), the organic solvent containing the generated semiconductor nanoparticles is subjected to centrifugation to obtain a supernatant after centrifugation. (D) An organic solvent is added to the supernatant. The method for producing semiconductor nanoparticles according to any one of claims 1 to 6, further comprising taking out the semiconductor nanoparticles as a precipitate by centrifugation. Preparing a dispersion in which the semiconductor nanoparticles produced by the method according to any one of claims 1 to 7 are dispersed in a solvent;
A compound containing a group 13 element and a group 16 element or a compound containing a group 16 element are added to the dispersion to substantially add the group 13 element and the group to the surface of the semiconductor nanoparticle. A method for producing core-shell type semiconductor nanoparticles, comprising forming a semiconductor layer comprising a group 16 element.   The method for producing core-shell semiconductor nanoparticles according to claim 8, wherein Ga is contained as the Group 13 element and S is contained as the Group 16 element. A semiconductor nanoparticle containing Ag, In, and S having an average particle size of 50 nm or less,
The ratio of the number of Ag atoms to the total number of Ag and In atoms is 0.320 or more and 0.385 or less,
The ratio of the number of S atoms to the total number of Ag and In atoms is 1.20 or more and 1.45 or less,
When light having a wavelength in the range of 350 to 500 nm is irradiated, it emits light having an emission lifetime of 200 ns or less.
Semiconductor nanoparticles. A core-shell type semiconductor nanoparticle comprising a core and a shell that covers the surface of the core and heterojunction with the core,
The core includes Ag, In, and S, the ratio of the number of Ag atoms to the total number of Ag and In atoms is not less than 0.320 and not more than 0.385, and S relative to the total number of Ag and In atoms The ratio of the number of atoms of the semiconductor is 1.20 or more and 1.45 or less,
The shell is a semiconductor substantially composed of a Group 13 element and a Group 16 element;
In the emission spectrum obtained when light having a wavelength in the range of 350 to 500 nm is irradiated, an emission peak having a peak wavelength in the range of 550 nm to 650 nm and a half width of 80 nm or less is observed.
Core-shell type semiconductor nanoparticles.   The core-shell type semiconductor nanoparticle according to claim 11, comprising Ga as the Group 13 element and S as the Group 16 element.   A light emitting device including a light conversion member and a semiconductor light emitting element, wherein the light conversion member includes the semiconductor nanoparticles according to claim 10.   A light emitting device including a light conversion member and a semiconductor light emitting element, wherein the light conversion member includes the core-shell type semiconductor nanoparticles according to claim 11 or 12.   The light emitting device according to claim 13 or 14, wherein the semiconductor light emitting element is an LED chip.