JP2006335873A - Fluorescent substance obtained by dispersing semiconductor nano particles in inorganic matrix - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inorganic matrix fluorescent substance achieving excellent temporal stability, chemical stability, heat resistance, mechanical characteristics and the like while keeping the high luminous efficiency of nano particles in the matrix; and to provide an optical device such as a lighting device and a display device by using the fluorescent substance. <P>SOLUTION: The fluorescent substance is obtained by dispersing semiconductor nano particles having ≥25% luminous efficiency in the inorganic matrix so that the concentration may be ≥10<SP>-5</SP>mol/l, and has ≥500 MPa Vickers hardness and ≥1.7 specific gravity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a phosphor in which semiconductor nanoparticles are dispersed in an inorganic matrix and a method for producing the same.

  Today, phosphors are widely used as lighting and display materials to support everyday life. As this phosphor, an inorganic matrix in which transition element ions (transition metal ions and rare earth ions) are dispersed has long been used.

On the other hand, in recent years, it has been found that semiconductor nanoparticles devised by a production method exhibit high efficiency light emission. The semiconductor nanoparticles are typically II-VI group compounds such as cadmium selenide, cadmium telluride, cadmium sulfide, and zinc selenide, and have a diameter of about 2 to 5 nanometers. These semiconductor nanoparticles are attracting attention as a new type of fluorescent material because the emission decay time is short and the emission wavelength can be controlled by the particle size.

  Such semiconductor nanoparticles have a large surface ratio due to their small particle size. The surface usually has a large number of defects, which cause non-radiation deactivation. For this reason, the surface inactivation treatment is performed by various methods. For this inactivation, an organic surfactant containing sulfur such as thiol or zinc sulfide is used.

  As a method for producing the semiconductor nanoparticles, a method using a surfactant in an aqueous solution is well known. (Non-Patent Document 1). However, the semiconductor nanoparticles produced by the aqueous solution method are unstable in the aqueous solution and are not suitable for industrial application.

  For this reason, a method for fixing semiconductor nanoparticles to a polymer made of an organic substance has been reported (Non-Patent Document 2). However, the polymer used as a matrix has insufficient light resistance, heat resistance, chemical resistance, etc., and also allows water and oxygen to pass through little by little, so that the immobilized nanoparticles gradually deteriorate. was there.

In order to overcome such drawbacks of the polymer, research on dispersing semiconductor nanoparticles in a glass matrix using a sol-gel method is in progress. In this method, a surfactant (such as thioglycolic acid (TGA)) is used to improve the dispersibility of nanoparticles in water, and organoalkoxysilane ( For example, the formula: M (OR ¹ ) _4-n R ² _n , wherein M is Si, R ¹ is a lower alkyl group, R ² is an organic group such as an aminoalkyl group, n is 1, 2 or 3) Are preferably used.

Specifically, for example, Patent Document 1 discloses 3-aminopropyltrimethoxysilane (APS).
) And 3-mercaptopropyltrimethoxysilane (MPS) and other organoalkoxysilanes using a sol-gel method, 5 × 10 ⁻⁴ to 1 × 10 ⁻² mol of cadmium telluride nanoparticles are contained in a solid matrix containing silicon. It is described that a phosphor having a luminous efficiency of 3% or more can be produced at a concentration of 1 / liter.

Patent Document 2 discloses that a concentration of 2 × 10 ⁻⁶ to 2 × 10 ⁻⁴ mol / liter of semiconductor nanoparticles having a luminous efficiency of 20% or more in a matrix formed by a sol-gel method using APS or the like. And phosphors dispersed therein are described.

Similarly, in Non-Patent Documents 3 and 4, the dispersibility of the nanoparticles in the matrix is increased by mixing organoalkoxysilane (APS, MPS, etc.).

  In this way, semiconductor nanoparticles are uniformly dispersed in the glass matrix by a sol-gel reaction using semiconductor nanoparticles, surfactants, organoalkoxysilanes, etc., thereby preventing deterioration of the nanoparticles and improving stability over time. It is possible.

  However, this phosphor has a glass property and a polymer property, and the heat resistance and chemical resistance have not necessarily reached the level required for the phosphor. Accordingly, when considering further stability over time, chemical stability, heat resistance, mechanical properties, etc. of the phosphor, it is advantageous that the glass matrix contains as little organic matter as possible.

By the way, Non-Patent Document 5 reports that ultrafine particles are dispersed in a glass matrix by a sol-gel method using tetraalkoxysilane containing no organic group in the molecule. However, this method has the drawback that the means of the sol-gel method are limited because the ultrafine particles are not water-soluble, and only a gel-like material can be obtained. Furthermore, since the luminous efficiency of the nanoparticles in the obtained phosphor is low, it is far from practical use.

As described above, there is a strong demand for inorganic matrix phosphors that can achieve higher aging stability, chemical stability, heat resistance, mechanical properties, etc. while maintaining high luminous efficiency of nanoparticles in the matrix. It was.
International Publication No. 2004/000971 Pamphlet International Publication No. 2004/065296 Pamphlet Gao et al., Journal of Physical Chemistry, B, 102, 8360, 1998 Bavendy et al., Advanced Materials, Vol. 12, p. 1103 (2000) Chang et al., Advanced Materials, 16, 2092, 2004 Nan et al., Angelevante Chemie International Edition, 43, 5393 pages, 2004 Selvan et al., Advanced Materials, 13, 985 pages (2001)

  The main object of the present invention is to provide an inorganic matrix phosphor capable of achieving excellent temporal stability, chemical stability, heat resistance, mechanical strength, etc. while maintaining high luminous efficiency of nanoparticles in the matrix. In addition, an optical device such as an illumination device or a display device using the same is supplied.

  As a result of intensive research to achieve the above-mentioned object, the present inventor introduced water-dispersible nanoparticles into a glass matrix under a predetermined condition using tetraalkoxysilane having no organic group in the molecule. The present inventors have found that the obtained phosphor has high luminous efficiency and excellent temporal stability, chemical stability, heat resistance, mechanical properties, and the like.

Specifically, since the alcohol used for the sol-gel reaction is a typical poor solvent for nanoparticles, an attempt was made to proceed with the sol-gel reaction by removing alcohol as much as possible when introducing the nanoparticles. In addition, an attempt was made to appropriately select pH, temperature, rate of solution addition, and the like during the sol-gel reaction. As a result, it has become possible to uniformly disperse the glass in the glass while shortening the gel time and substantially maintaining the luminous efficiency of the nanoparticles in the aqueous solution. And this glass phosphor
It was found to be harder, higher in specific gravity and superior in chemical resistance than those using conventional organoalkoxysilanes. As a result of further research based on this finding, the present invention has been completed.

  That is, this invention provides the following inorganic matrix fluorescent substance and its manufacturing method.

  Item 1. A phosphor in which semiconductor nanoparticles with a luminous efficiency of 25% or more are dispersed in an inorganic matrix.

Item 2. Item 2. The phosphor according to Item 1, wherein the semiconductor nanoparticles are dispersed in an inorganic matrix at a concentration of 10 ⁻⁵ mol / liter or more.

  Item 3. Item 3. The phosphor according to Item 1 or 2, wherein the Vickers hardness is 500 MPa or more.

  Item 4. Item 4. The phosphor according to Item 1, 2, or 3 having a specific gravity of 1.7 or more.

  Item 5. Item 5. The phosphor according to any one of Items 1 to 4, wherein the inorganic matrix is produced by a sol-gel method using a metal alkoxide.

  Item 6. Item 6. The phosphor according to Item 5, wherein the metal alkoxide is at least one selected from the group consisting of tetraalkoxysilane, tetraalkoxyzirconium, tetraalkoxytitanium and trialkoxyaluminum.

  Item 7. Item 7. The phosphor according to any one of Items 1 to 6, wherein the semiconductor nanoparticles are at least one selected from the group consisting of cadmium selenide, cadmium telluride, cadmium sulfide, and zinc selenide.

  Item 8. Item 8. A light emitting device comprising the phosphor according to any one of items 1 to 7.

  Item 9. Item 9. The light emitting device according to Item 8, comprising a cooling device or a heat radiation material for maintaining the temperature of the glass phosphor at 50 ° C or lower.

  Item 10. A method for producing a phosphor in which semiconductor nanoparticles having a luminous efficiency of 25% or more are dispersed in an inorganic matrix, wherein (1) a metal alkoxide, alcohol, water and acid are mixed to obtain a hydrolyzed solution of metal alkoxide, (2) After removing most of the alcohol from the hydrolysis solution, and (3) further adjusting the pH to 5.5 to 8.5, (4) a dispersion of semiconductor nanoparticles having a luminous efficiency of 25% or more, and And then curing the phosphor.

  Item 11. Furthermore, the phosphor after curing in the above (4) is subjected to a heat treatment, The method for producing a phosphor according to Item 10.

As used herein, “emission efficiency of semiconductor nanoparticles in solution” is the ratio of the number of photons (Φ _PL ) emitted as photoluminescence to the number of photons (Φ _A ) absorbed. It is defined as (Φ _PL / Φ _A ). This luminous efficiency is a value that is used as standard in this technical field, and is synonymous with “internal quantum yield”. Luminous efficiency is calculated by using a dye molecule having a known luminous efficiency and comparing the absorbance at the excitation light wavelength and the emission intensity in the dye molecule solution and the measurement object. At the time of measurement, comparison is usually made by matching the absorbance at the excitation wavelength of the dye molecule solution and the measurement object. (See, for example, previously reported methods, Dawson et al., Journal of Physical Chemistry, 72, 3251 (1968)).

In the present specification, “the luminous efficiency of the semiconductor nanoparticles in the phosphor” refers to the photon number (Φ _A ) of excitation light absorbed by the semiconductor nanoparticles in the phosphor. is defined as the ratio (Φ _PL / Φ _a) of photons emitted as photoluminescence from nanoparticles (photons) number ([Phi _PL). Specifically, a glass cell containing a dye molecule solution with known absorbance and luminous efficiency, and a glass serving as a measurement object having the same thickness are prepared, and the absorbance in the dye molecule solution and the measurement object is determined. It is a value calculated by comparing the emission intensity. The same principle is used when the phosphor is powder or when scattering is large. However, in this case, the amount of light absorption is measured by measuring the scattering intensity of excitation light when a white scatterer (magnesium oxide or the like) is attached to the surface of the integrating sphere and when the sample is attached. The light emission intensity from the sample is measured and calculated.

More specifically, in the present invention, 0.5 M of quinine is used as a dye having a known luminous efficiency.
A sulfuric acid aqueous solution (luminous efficiency 54.6%) is used. Fluorescence intensity is measured by packing several kinds of quinine solutions in several cells with different thicknesses. From the results, the luminous efficiency of phosphors (glass plates) with multiple thicknesses in which nanoparticles are dispersed at an arbitrary concentration is measured. The method of deriving was adopted. It is necessary to correct the luminous efficiency of the phosphor using the refractive index. When the refractive index of the phosphor of the present invention was measured by ellipsometry, a value of 1.35 to 1.36 was obtained in the emission wavelength range of 500 to 600 nanometers. On the other hand, it is clear from the Chemical Handbook, Fundamental II, page 553 (Revised 3rd edition, Maruzen Co., Ltd.) in the Chemical Handbook, Fundamental II, that the refractive index of the aqueous solution compared with the dye is 1.33 in the same wavelength range. . Thus, since the refractive index values of the two are very close, the phosphor of the present invention does not require correction by the refractive index.

The present invention is described in detail below.
I. Semiconductor nanoparticles As the semiconductor nanoparticles of the present invention, fluorescent semiconductor nanoparticles having water dispersibility are preferably used. Specific examples include II-VI group compound semiconductors that exhibit direct transition and emit light in the visible region. For example, cadmium sulfide, zinc selenide, cadmium selenide, zinc telluride, cadmium telluride and the like can be exemplified, and cadmium telluride or zinc selenide is preferable. The semiconductor nanoparticles of the present invention are present in a stabilized state in an aqueous solution containing a surfactant.

  As a manufacturing method of a semiconductor nanoparticle, it can manufacture according to the said patent document 1 and 2, for example.

Specifically, a group II-VI semiconductor can be obtained by introducing a group VI element compound into an alkaline aqueous solution in which a water-soluble compound containing a group II element and a surfactant are dissolved in an inert atmosphere. it can. A gaseous group VI element compound can also be used.

  As the water-soluble compound containing a Group II element, a perchlorate is preferable. For example, when the Group II element is cadmium, cadmium perchlorate can be used. The concentration of the water-soluble compound containing a group II element in the aqueous solution is usually about 0.001 to 0.05 mol / liter, more preferably about 0.01 to 0.02 mol / liter, particularly 0.013 to 0.018. It is preferably about mol / liter.

As the surfactant, those having a thiol group which is a hydrophobic group and a hydrophilic group are preferable. Examples of the hydrophilic group include an anionic group such as a carboxyl group, a cationic group such as an amino group, and a hydroxyl group, and an anionic group such as a carboxyl group is particularly preferable. Specific examples of this surfactant include thioglycolic acid, thioglycerol, mercaptoethylamine, and the like. The amount of the surfactant used is about 1 to 2.5 mol, preferably about 1 to 1.5 mol, per 1 mol of group II element ions contained in the aqueous solution. When the usage-amount of surfactant exceeds the said range, there exists a tendency for the luminous efficiency of the nanoparticle obtained to fall.

  As the group VI element compound, for example, a hydride of a group VI element can be used. When the group VI element is tellurium, hydrogen telluride can be used. In addition, it is also possible to introduce sodium telluride obtained by reacting hydrogen telluride with sodium hydroxide as an aqueous solution. The use amount of the group VI element compound is usually about 0.3 to 1.5 mol and more preferably about 0.4 to 0.9 mol with respect to 1 mol of the group II ion. It is preferable.

  The water used for the production of the semiconductor nanoparticles is preferably high-purity water. In particular, it is more preferable to use ultrapure water having a specific resistance of 18 MΩ · cm or more and a total amount (TOC) of organic compounds in water of 5 ppb or less, preferably 3 ppb or less. By sufficiently washing the reaction vessel and the like with such high-purity water and using high-purity water as the reaction solvent, it is possible to obtain semiconductor nanoparticles having excellent light-emitting performance.

  The above reaction is usually carried out by bubbling a gaseous group VI element compound in an aqueous solution in which a water-soluble compound containing a group II element and a surfactant are dissolved in an inert atmosphere, or by adding a gaseous group VI compound. The reaction can be carried out by reacting with a sodium hydroxide solution to make an aqueous solution and then injecting it into an aqueous solution in which a water-soluble compound containing a group II element and a surfactant are dissolved with a syringe or the like.

  The inert atmosphere may be a gas atmosphere that does not participate in the reaction. For example, an inert gas atmosphere such as argon gas, nitrogen gas, and helium gas can be suitably used.

  The above reaction can usually be performed at room temperature (for example, about 10 to 30 ° C.). The pH of the aqueous solution is preferably about 10 to 12, particularly 10.5 to 11.5. The reaction is usually completed within about 10 minutes after introducing the group VI compound.

Thereafter, by refluxing in the atmosphere, an aqueous solution in which semiconductor nanoparticles of a desired size are dispersed is obtained. The concentration of the nanoparticles in the aqueous solution is appropriately selected depending on the reaction conditions, but is usually 1 × 10 ⁻⁷ mol / liter to 3 × 10 ⁻⁶ mol / liter, typically 3 × 10 ^−7. It is about 2 × 10 ⁻⁶ mol / liter, particularly about 1 × 10 ⁻⁶ mol / liter.

The particle size of the manufactured semiconductor nanoparticles is usually about 2 to 5 nm. Increasing the reflux time can increase the particle size. The emission color of the semiconductor nanoparticles is determined by the particle size, and the smaller the particle size, the shorter the wavelength. If the semiconductor nanoparticles have the same particle size, light emission of a single color can be obtained, and if particles of various particle sizes are mixed, light emission corresponding to the color tone can be obtained.

  In order to obtain nanoparticles emitting in a single color, the reflux time is controlled to be constant, and the standard deviation of the dispersion of the particle size distribution is 20% or less, preferably 15% or less with respect to the average value of the particle size. You just have to make adjustments.

  The aqueous solution of semiconductor nanoparticles obtained in this manner usually contains Group II element ions, surfactants, fine clusters of less than 1 nanometer, etc. used as raw materials. Using this aqueous solution of semiconductor nanoparticles, the semiconductor nanoparticles can be dispersed as they are in an inorganic matrix by the method described later to obtain a phosphor.

Furthermore, the nanoparticles contained in the aqueous solution can be separated for each nanoparticle having a uniform particle diameter. For example, using the fact that the solubility decreases as the particle size of the nanoparticles increases,
By adding a poor solvent such as isopropanol to the aqueous solution of nanoparticles, the nanoparticles are precipitated according to size and separated by centrifuging.

The nanoparticles purified in this way can be redispersed in water to form an aqueous solution, and in this case, the nanoparticles exhibit high luminous efficiency. The aqueous solution is stable to some extent as it is, but by adding a water-soluble compound containing a group II element and a surfactant to the aqueous solution, the stability of the aqueous solution is improved, and aggregation is prevented and luminous efficiency is improved. Can keep. The kind of the group II element compound, the concentration of the compound, the amount of the surfactant, the pH of the aqueous solution, and the like may be adjusted in the same range as the aqueous solution used for producing the above-described group II-VI semiconductor nanoparticles.

Specifically, II-VI group semiconductor nanoparticles (about 1 × 10 ^{−7 to} 3 × 10 ⁻⁶ mol / liter, preferably about 3 × 10 ⁻⁷ to 2 × 10 ⁻⁶ mol / liter), II II, a raw material for Group VI semiconductor nanoparticles
Water-soluble compound containing a group element (Group II element ion) (about 0.001 to 0.05 mol / liter, preferably about 0.01 to 0.02 mol / liter, more preferably 0.013 to 0.018) About pH 10-12 (preferably about 0.5 to 5 mol, preferably about 1 to 1.5 mol) per 1 mol of group II element ions contained in the aqueous solution. Is preferably about 10.5 to 11.5).

In addition, semiconductor nanoparticles such as cadmium selenide can be produced in an organic solvent by utilizing thermal decomposition of an organic metal. Since the semiconductor nanoparticle surface substituted with a thiol-based surfactant such as TGA has water dispersibility, it can be used as an aqueous solution of semiconductor nanoparticles. This is known as a known method (Bavendy et al., JP-T-2002-525394).

  The semiconductor nanoparticles obtained by the above method have good water dispersibility and high luminous efficiency. The luminous efficiency of the semiconductor nanoparticles in this aqueous solution is about 25 to 85%. In particular, in the case of red-emitting semiconductor nanoparticles, luminous efficiency of about 70% can be obtained without post-treatment such as light irradiation after adjustment. Here, the luminous efficiency of the nanoparticles in the aqueous dispersion greatly affects the luminous efficiency of the completed phosphor.

In particular, in the case of using zinc selenide nanoparticles, the luminous efficiency increases to about 35% when ultraviolet irradiation treatment is performed after the production by the above method using thioglycolic acid as a surfactant. For details, please follow the method described in Japan Ceramic Society, 2005 Annual Meeting, Lecture Proceedings 2E02 (page 98).

Using the aqueous solution of semiconductor nanoparticles, the nanoparticles are dispersed in the inorganic matrix by the method described later. Accordingly, the nanoparticles can be present in a high concentration in the inorganic matrix and can be present at a high concentration, and can maintain a high luminous efficiency, thereby obtaining a phosphor having excellent performance. The use of an aqueous solution in which purified nanoparticles are re-dispersed in water is particularly excellent.
II. Method for Producing Phosphor A phosphor obtained by dispersing semiconductor nanoparticles having a luminous efficiency of 25% or more in the inorganic matrix of the present invention includes, for example, (1) a metal alkoxide mixed with a metal alkoxide, alcohol, water and acid. (2) After removing most of the alcohol from the hydrolysis solution, (3) further adjusting the pH to 5.5 to 8.5, and (4) semiconductor nanometers having a luminous efficiency of 25% or more. After mixing with the particle dispersion, it can be produced by curing.

The metal alkoxide used in the above (1) is tetraalkoxysilane (Si (OR) ₄ ), tetraalkoxy zirconium (Zr (OR) ₄ ), tetraalkoxy titanium (Ti (OR) ₄ ), trialkoxy aluminum (Al ( OR) ₃ ) etc. are exemplified. R is an alkoxy group, preferably a C _1-4 alkoxy group. Specifically, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetraethoxyzirconium, tetraisopropoxyzirconium, tetrabutoxyzirconium, tetraethoxytitanium, tetraisopropoxytitanium, tetrabutoxytitanium, triethoxyaluminum, triisosodium Examples include propoxyaluminum and tributoxyaluminum. Among these, a metal alkoxide can use 1 type, or 2 or more types. Tetraalkoxysilane is preferably used as the metal alkoxide, and tetraethoxysilane is more preferable. When mixing 2 or more types, it is preferable to use tetraethoxysilane as a main component (for example, 80 mol% or more).

  Further, a metal alkoxide in which tetraalkoxysilane and tetraalkoxyzirconium are mixed is preferable from the viewpoint of chemical stability and mechanical properties (for example, Example 3). In this case, the molar ratio of tetraalkoxysilane to tetraalkoxyzirconium is preferably about 100: 0 to 80:20, particularly about 90:10 to 95: 5.

Moreover, what mixed tetraalkoxysilane and tetraalkoxy titanium as a metal alkoxide is suitable from the point of luminous efficiency (for example, Example 6). The molar ratio of tetraalkoxysilane and tetraalkoxytitanium is preferably about 100: 0 to 80:20, particularly about 85:15 to 95: 5.

In the present invention, a metal alkoxide is used as a raw material. However, as long as it does not adversely affect the operational effects of the present invention, the general formula:
X _m -Si (OR ') _4-m
(Wherein X represents an aminoalkyl group, mercaptoalkyl group, etc., R ′ represents a C _1-3 alkyl group, m = 1, 2 or 3)
An organoalkoxysilane represented by the following formula may be added. Examples of the organoalkoxysilane include 3-aminopropyltrimethoxysilane (APS) and 3-mercaptopropyltrimethoxysilane (MPS). Usually, the molar ratio between the metal alkoxide and the organoalkoxysilane may be about 100: 0 to 90:10.

Examples of the alcohol used in the above (1) include C _1-4 alcohols such as methanol, ethanol, propanol, isopropanol, and butanol. It is preferable to use an alcohol corresponding to the alkoxide of the metal alkoxide to be used. For example, when tetraethoxysilane is used as the metal alkoxide, ethanol is used as the alcohol.

  Examples of the acid used in the above (1) include hydrochloric acid, acetic acid, nitric acid and the like. The amount of acid used may be a catalytic amount. The use of an acid in the sol-gel method is because the hydrolysis of the metal alkoxide is fast under acid conditions, but the subsequent dehydration reaction is slow, so the time that is retained in the form of a metal hydroxide (for example, silanol) that is a reaction intermediate is used. become longer. Therefore, since it is held in a sol state for a long time until the semiconductor nanoparticles are mixed, it is possible to secure a pot life necessary for the later-described alcohol removal and pH adjustment. In the case of using a base, the hydrolysis of the metal alkoxide is slow, but since the subsequent dehydration reaction is fast, gelation proceeds rapidly, which is not preferable.

  The compounding quantity of metal alkoxide (when organoalkoxysilane is included, the total of organoalkoxysilane and metal alkoxide), alcohol, and water may be a molar ratio of about 1: 1 to 60: 1 to 200. The acid may be a catalytic amount as described above.

  When mixing each component, it is usually sufficient to stir at about 15 to 80 ° C. for about 5 minutes to 1 hour. The temperature at the time of mixing can be suitably selected according to the kind etc. of metal alkoxide. When two or more kinds of metal alkoxides mainly composed of tetraalkoxysilane are mixed, alcohol of other metal alkoxides is added to the hydrolysis solution obtained by adding alcohol, water and a catalytic amount of acid to tetraalkoxysilane. What is necessary is just to dripping a solution. The reaction temperature may be room temperature or warm. Usually, stirring may be performed at about 30 to 80 ° C.

  Thereby, the hydrolysis solution of the metal alkoxide of about pH 3-5 is prepared.

Next, in (2) above, most of the alcohol is removed from the metal alkoxide hydrolysis solution obtained in (1) above. This is because the alcohol used for the sol-gel reaction is a typical poor solvent that hinders dispersion of the semiconductor nanoparticles, and therefore it is preferable to introduce the nanoparticles after removing the alcohol as much as possible. Usually, a method of spontaneously evaporating alcohol by stirring for 2 to 15 hours at room temperature (about 10-30 ° C) and normal pressure (about 0.1 MPa) or a method of distilling off the alcohol under reduced pressure is used. It is done.

  Although it is not easy to specifically define the removal ratio of the alcohol from the hydrolyzed solution, most of it should be removed. Usually, the viscosity of the hydrolysis solution increases in accordance with the removal of the alcohol content. For example, the viscosity of the hydrolysis solution is about 200 to 3000 mPa · s, preferably about 500 to 2000 mPa · s, more preferably The alcohol may be removed until the pressure reaches about 700 to 1500 mPa · s.

  Next, in (3) above, the pH of the hydrolysis solution from which the alcohol obtained in (2) has been removed is adjusted to 5.5 to 8.5. The hydrolyzed solution of (1) is acidic due to the acid catalyst, so the pH is adjusted to 5.5 to 8.5 using an aqueous alkali (eg, sodium hydroxide, potassium hydroxide) solution. . When the pH rises, the dehydration condensation reaction of the sol-form hydrolysis solution is promoted.

  When only tetraalkoxysilane is used as the metal alkoxide, the pH of the hydrolysis solution is preferably about 5.5 to 6.5. When tetraalkoxysilane and tetraalkoxyzirconium are used, The pH of the decomposition solution is preferably about 7.5 to 8.5, and when tetraalkoxysilane and tetraalkoxytitanium are used, the pH of the hydrolysis solution should be about 6.5 to 7.5. preferable.

  Next, in the above (4), the hydrolyzed solution prepared in the above (3) and prepared to have a pH of about 5.5 to 8.5, and the semiconductor nanoparticle prepared in the section “I. Semiconductor nanoparticles”. Mix and cure with aqueous solution of particles.

Specifically, the aqueous solution of the semiconductor nanoparticles is II-VI group semiconductor nanoparticles (1 × 10 ^{−7 to} 3 × 10 ⁻⁶
Mol / liter, preferably about 3 × 10 ⁻⁷ to 2 × 10 ⁻⁶ mol / liter), a water-soluble compound (group II element ion) containing a group II element that is a raw material for group II-VI semiconductor nanoparticles (About 0.001 to 0.05 mol / liter, preferably about 0.01 to 0.02 mol / liter, more preferably about 0.013 to 0.018 mol / liter), and a surfactant (in an aqueous solution) An aqueous solution having a pH of about 10 to 12 (preferably about 10.5 to 11.5) containing about 0.5 to 5 mol, preferably about 1 to 1.5 mol) per 1 mol of group II element ions contained in Is preferred.

  Since the hydrolyzed solution prepared in the above (3) is likely to undergo a dehydration condensation reaction, it is preferable to immediately mix with the aqueous solution of semiconductor nanoparticles after the preparation. What is necessary is just to stir and mix the both at normal temperature normal pressure.

The resulting mixture is allowed to stand at room temperature for about 2 to 14 days to produce a phosphor in which curing proceeds and semiconductor nanoparticles are dispersed in an inorganic matrix. The phosphor has a Vickers hardness of 500 MPa or more, about 550 to 1000 MPa, particularly about 600 to 1000 MPa. Moreover, the specific gravity becomes 1.7 or more and also a high value of 1.7-2.2. Further, the luminous efficiency is 25% or more, further 30% or more, particularly about 35 to 80%.

Further, the obtained phosphor can be heat-treated at about 80 to 100 ° C. for about 1 to 5 hours to obtain a phosphor with improved hardness and specific gravity. The phosphor has a Vickers hardness of 600 MPa or more, about 650 to 1000 MPa, particularly about 700 to 1000 MPa. Also,
Its specific gravity is 1.8 or more, and further high values of 1.8 to 2.4. Further, the luminous efficiency is 25% or more, further 30% or more, particularly about 35 to 80%.

  Next, a more specific manufacturing example of the phosphor will be described.

  First, a method for dispersing semiconductor nanoparticles in an inorganic matrix produced by a sol-gel method of tetraethoxysilane will be described.

After diluting tetraethoxyorthosilicate (TEOS) with ethanol, water and a small amount of hydrochloric acid are added and stirred for 2 to 3 hours to partially hydrolyze TEOS to obtain a hydrolyzed solution. Thereafter, the hydrolysis solution is stirred for about 5 to 10 hours to evaporate most of the ethanol. The hydrolyzed solution has a viscosity of about 700 to 1500 mPa · s. Next, the pH of the hydrolyzed solution is adjusted to about 6.5 to 7.5 with an aqueous sodium hydroxide solution and poured into a Teflon (registered trademark, hereinafter the same) petri dish. Add cadmium telluride dispersion to this and stir quickly. Furthermore, this is left at room temperature for about 3 to 5 days to obtain a glass phosphor. Furthermore, it is possible to improve the glass quality by carrying out heat treatment for several hours at a temperature of about 80 to 100 ° C. to advance the dehydration condensation reaction.

  Next, a method for dispersing semiconductor nanoparticles in an inorganic matrix in which zirconia is mixed with silica will be described. The glass mixed with zirconium is further improved in chemical stability, heat resistance, and the like as compared with glass containing only silica.

Add ethanol, water and a small amount of hydrochloric acid to TEOS and stir for about 1 hour to partially hydrolyze to obtain a hydrolyzed solution. A solution of zirconium propoxide in ethanol is added dropwise to the TEOS partial hydrolysis solution, and the mixture is heated and stirred at 65 to 75 ° C. for about 20 to 60 minutes to obtain a hydrolysis solution. After cooling to room temperature, water and a small amount of hydrochloric acid may be added. 3 more
Stir for ~ 10 hours to evaporate most of the ethanol. The hydrolyzed solution has a viscosity of about 700 to 1500 mPa · s. Then, after adjusting pH to about 7.5-8.5 and pouring this into a Teflon petri dish, the cadmium telluride nanoparticle dispersion solution is added and stirred rapidly. If left at room temperature for about 4 to 6 days, a uniform glass phosphor is completed. In addition, 80-100
It is possible to improve the glass quality by carrying out a heat treatment for several hours at a temperature of about 0 ° C. to advance the dehydration condensation reaction.

  In addition, a decrease in luminous efficiency can be prevented by optimizing the amount and pH of water and reducing the gelation time. The gelation time is preferably 20 minutes or less, and more preferably 10 minutes or less. The molar ratio of silicon to zirconium is about 80:20 to 98: 2, preferably about 90:10 to 95: 5. FIG. 1 shows a photograph of the obtained nanoparticle-dispersed silica zirconia glass phosphor and a schematic diagram of the state of dispersion.

The phosphor of the present invention formed by the method described above basically exhibits the properties of glass, and is more stable over time than phosphors produced using conventional organoalkoxysilanes. It has excellent properties such as stability, chemical stability, heat resistance and mechanical properties.

In the case of a phosphor using organoalkoxysilane together with metal alkoxide as a raw material, the content of organoalkoxysilane in the phosphor can be determined by conducting elemental analysis. Since APS is frequently used as the organoalkoxysilane, nitrogen contained in the amino group is detected in this case. In addition, when organoalkoxysilane is included, the Vickers hardness generally decreases. In the phosphor of the present invention, the Vickers hardness is 500 MPa.
Since the above can be obtained, it can be distinguished from a phosphor using conventional APS (Vickers hardness of 490 MPa or less). Vickers hardness is, for example, Shimadzu Vicker Tester (HMV-1)
Can be measured by applying a 10 gram weight for 15 seconds.

In the phosphor of the present invention, the network structure is highly developed as the sol-gel reaction progresses. For this reason, the shrinkage is remarkably increased and the hardness and specific gravity are increased. In the case of the phosphor using the conventional organoalkoxysilane (for example, APS), the specific gravity is about 1.4, whereas in the phosphor of the present invention, as an example, the phosphor is composed only of silica. The specific gravity is 1.73 ± 0.01, and it is heat treated at 100 ° C. for 3 hours to be about 1.78 ± 0.02. In addition, the silica zirconia phosphor is 1.89 ± 0.01, and is heat-treated at 100 ° C. for 3 hours to produce 2.01 ± 0.01 and over 1.7.

In the present invention, since the nanoparticles are firmly protected by such a matrix having a high hardness or a matrix having a high specific gravity, it is excellent in stability over time, chemical stability, heat resistance, mechanical properties, and the like.
III. The phosphor obtained by the method more than the use of the phosphor has high brightness and exhibits various colored light by irradiation with light of a single wavelength. A light emitting device as shown below (instead of the conventional phosphor) ( It can be effectively used as a phosphor for lighting devices and display elements.

White illumination light can be obtained by combining semiconductor nanoparticles with an appropriate particle size in accordance with excitation by an illumination device, particularly a mercury lamp with a wavelength of 365 nm or an ultraviolet LED. In addition, it can be used as an illumination as a liquid crystal backlight such as a cold cathode fluorescent lamp, a light source for a liquid crystal projector for presentation using a mercury lamp, and the like.

Display element (display, etc.)
A flat plate coated with the glass phosphor as a fine pattern is used. A glass containing nanoparticles that emit three colors of RGB, for example, is applied alternately to a large number of dots with a diameter of about 0.1 mm, and the desired display is achieved by irradiating ultraviolet light with intensity modulated according to the information signal. Is obtained. For the excitation light source in this case, it is necessary to select a wavelength in a range where there is no absorption of the matrix. When the wavelength is less than 320 nm, matrix absorption often occurs. Therefore, for example, it is preferable to use a light source having a wavelength of about 320 nm to 600 nm, such as a mercury lamp, an LED, or a solid laser.

  In particular, when intense excitation light is irradiated, the temperature of the phosphor rises and the deterioration is accelerated. The activation energy for deterioration is about 300 meV. For this reason, in order to make it last longer, it is desirable that the operating temperature is as low as possible. For that purpose, it is preferable to devise the arrangement of the excitation light source and to include a cooling device and a heat dissipation material. Examples of the cooling device include a powerful cooling fan and water cooling, and examples of the heat dissipation material include metals and ceramics.

  In the phosphor of the present invention, semiconductor nanoparticles stably exist in a glass matrix having high hardness and specific gravity, and the semiconductor nanoparticles maintain high luminous efficiency and a high concentration state. Therefore, the phosphor of the present invention becomes a phosphor more suitable for practical use.

  Such a phosphor is suitably used as an optical device such as a high-luminance display device or illumination device in place of the conventional phosphor.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1
A nanoparticle-dispersed glass phosphor having only tetrafunctional silica as a matrix was produced.

Cadmium telluride nanoparticles dispersed in water were prepared according to a previously reported method (Li, Murase, Chemistry Letters, 34, 92 pages, 2005). That is, cadmium perchlorate (hexahydrate, 1.095 g) was dissolved in 200 ml of water, and the surfactant thioglycolic acid (TGA) was added to the cadmium perchlorate by 1.25 times mole. To this, 1N aqueous sodium hydroxide solution was added to adjust to pH 11.4. After degassing for 30 minutes, hydrogen telluride gas was introduced with vigorous stirring under an inert atmosphere. After further stirring for 10 minutes, a condenser was attached and the mixture was refluxed at about 100 ° C. Cadmium telluride particles grew with the reflux, and the emission wavelength shifted from green to red.

First, at the initial stage of reflux, a solution containing green-emitting cadmium telluride nanoparticles (diameter of about 3 nm) (hereinafter referred to as solution 1) was taken out. Cadmium telluride is a surfactant TGA
Covered with water and stabilized in water.

Next, tetraethylorthosilicate (TEOS) was mixed with ethanol and dissolved by stirring at room temperature for 10 minutes. Next, pure water and 0.1 M hydrochloric acid were mixed in this ethanol solution and stirred for about 1 hour to obtain a transparent solution. The molar ratio of TEOS, ethanol, water, and hydrochloric acid was 1: 10: 50: 1.5 × 10 ⁻³ . The pH of the solution was about 4. This solution was stirred for 9 hours to obtain a hydrolyzed solution in which TEOS was partially hydrolyzed while ethanol, which is a poor solvent, was blown to the nanoparticles. The hydrolysis solution was brought to pH 6 using 0.5M sodium hydroxide solution.

This hydrolysis solution was transferred to a Teflon petri dish, and 1 mL of the above solution 1 was quickly added thereto and stirred. When left at room temperature for 4 days, it solidified into a glass phosphor. This is phosphor 1.

  Next, a solution (referred to as Solution 2) containing red-emitting cadmium telluride nanoparticles (diameter: about 4 nm) obtained by sufficiently increasing the reflux time was taken out. A glass phosphor was produced from the solution 2 in the same manner as in the case of the solution 1 described above. This is called phosphor 2.

  Using absorption spectrophotometer (U-4000, manufactured by Hitachi, Ltd.) and fluorescence spectrophotometer (F-4500, manufactured by Hitachi, Ltd.), absorption and emission spectra of solution 1, solution 2, phosphor 1, and phosphor 2 were measured. The measurement results are shown in FIG.

In FIG. 2, (i) is the absorption spectrum of the green light-emitting glass phosphor 1, (ii) is the absorption spectrum of the red light-emitting glass phosphor 2, (iii) is the emission spectrum of the green light-emitting glass phosphor 1, and (iv) is The emission spectrum of the red light emitting glass phosphor 2 is shown. (V) is the emission spectrum of solution 1, (vi
) Shows the emission spectrum of solution 2.

From FIG. 2, it was confirmed that the emission spectrum of the nanoparticles hardly changed between the solution state and the glass phosphor. From this spectrum, the luminous efficiencies of phosphors 1 and 2 were found to be 30% and 42%, respectively. The concentration of nanoparticles was estimated to be 1.2 × 10 ⁻⁵ mol / liter for both phosphors 1 and 2.

  Furthermore, this phosphor 2 was heated in air at 80 ° C. for 3 hours to proceed with a dehydration condensation reaction, whereby a higher quality phosphor (heat treated phosphor 2) could be obtained. FIG. 3 shows changes in absorption and emission spectra of the red light emitting phosphor (phosphor 2) at this time. Although there was almost no change in the absorption spectrum, the emission efficiency decreased from 42% to 33% by heating, and the glass was clearly shrunk by the dehydration condensation reaction.

The hardness of phosphor 2 and heat-treated phosphor 2 was measured using the Shimadzu Vicker Tester (HMV-1).
Was measured by applying a 10 gram weight for 15 seconds. The measurement was performed 6 times at different locations, and the average and variation were obtained. As a result, the Vickers hardness of the phosphor 2 was 940 ± 10 MPa, and that of the heat-treated phosphor 2 was 1100 ± 40 MPa.

Further, the specific gravity of the phosphor 2 was measured several times at 20 ° C. with a standard specific gravity meter using a specific gravity bottle. As a result, the specific gravity of the phosphor 2 was 1.73 ± 0.01. 100 ° C
In the case of the phosphor heat treated for 3 hours (heat treated phosphor 3), it was 1.78 ± 0.02.

  It was shown that it was sufficiently higher than the specific gravity (1.4) of the glass phosphor prepared from the APS obtained in Comparative Example 1.

Comparative Example 1
According to the method described in Example 3 of Patent Document 2, a phosphor in which cadmium telluride nanoparticles were dispersed in a matrix using APS was produced, and this was further heat-treated at 100 ° C. for 3 hours to obtain a phosphor. .

  This phosphor had a Vickers hardness of 490 MPa and a specific gravity of 1.4.

Example 2
A green fluorescent glass phosphor was produced in the same manner as in Example 1. The change in luminous efficiency was examined by changing the concentration of nanoparticles in the phosphor. The results are shown in FIGS. 4 (a) and 4 (b).

In FIG. 4 (a), (i) is the absorption spectrum of a phosphor having a nanoparticle concentration of 1.5 × 10 ⁻⁵ mol / liter, (iii) is its emission spectrum, and (ii) is the nanoparticle concentration. Absorption spectrum of phosphor of 6.0 × 10 ⁻⁵ mol / liter, (iv) shows its emission spectrum. Moreover, what is shown as a colloid solution shows the spectrum of the nanoparticle dispersion | distribution aqueous solution before putting in glass.

  According to Fig.4 (a), it turns out that there is almost no change in an emission spectrum in a solution state and a glass fluorescent substance. It can also be seen that the position and shape of the emission spectrum does not change even when the concentration of nanoparticles in the glass phosphor increases.

According to FIG. 4B, when the concentration of the nanoparticles in the phosphor is 1.5 × 10 ^{−5 to} 6 × 10 ⁻⁵ mol / liter, the luminous efficiency is maintained at a high value of 30%. Recognize.

Example 3
A nanoparticle-dispersed glass phosphor having a matrix of tetrafunctional silica and zirconia was produced.

  A cadmium telluride nanoparticle-dispersed aqueous solution was prepared in the same manner as in Example 1. Let the green and red light emitting solutions be solutions 1 and 2, respectively.

TEOS, pure water, and ethanol were mixed at a 1: 1: 1 molar ratio. A small amount of hydrochloric acid was added to adjust the pH of the solution to 4, and the mixture was stirred for 1 hour to partially hydrolyze TEOS.

A solution of zirconium propoxide (Zr (OC ₃ H ₇ ) ₄ ) and an equal volume of ethanol was added dropwise to the TEOS partial hydrolysis solution prepared previously, and the mixture was further heated and stirred at 70 ° C. for 30 minutes. The molar ratio of silicon to zirconium in the solution was adjusted to 93: 7. After cooling to room temperature, hydrochloric acid diluted with pure water was added dropwise. At this time, the molar ratio of (zirconium + silicon): ethanol: water: hydrochloric acid was adjusted to 1: 5: 30: 0.002. The pH at this time was 4. This solution was stirred for 9 hours, and most of ethanol was removed to obtain a hydrolysis solution. The pH of this hydrolysis solution was adjusted to 8 with sodium hydroxide solution.

This hydrolyzed solution was transferred to a Teflon petri dish, and 1 ml of solution 1 was quickly added to promote gelation. A transparent glass phosphor was obtained by leaving it for about 5 days. A photograph and a schematic diagram of this phosphor are shown in FIG.

FIG. 5 shows changes in luminous efficiency when the concentration of nanoparticles in the glass phosphor is increased. It can be seen that the luminous efficiency of 40% is maintained even when the concentration of nanoparticles is increased to about 4 × 10 ⁻⁵ mol / liter.

Similarly, the solution 2 was added to produce a glass phosphor. FIG. 6 shows the relationship between the concentration of nanoparticles in the glass phosphor and the luminous efficiency. Also in this case, it can be seen that the luminous efficiency of 60% is maintained even when the concentration of the nanoparticles is increased to about 4 × 10 ⁻⁵ mol / liter. The value of 60% luminous efficiency is higher than any nanoparticle-dispersed solids reported so far.

When the Vickers hardness was measured by the same method as in Example 1, it was 730 MPa. When the specific gravity of this glass was measured by the same method as in Example 1, it was 1.89 ± 0.01. Furthermore, in the phosphor which was heat-treated at 100 ° C. for 3 hours, it was 2.01 ± 0.01.

  It was shown that it was sufficiently higher than the specific gravity (1.4) of the glass phosphor prepared from the APS obtained in Comparative Example 1.

Example 4
The relationship between the time until the silica zirconia glass phosphor gels and the luminous efficiency of the obtained glass was investigated.

The molar ratio of silicon and zirconium was 93: 7, and the concentration of nanoparticles in the glass was fixed at 3 × 10 ⁻⁵ mol / liter. By controlling the amount of water added to the nanoparticle dispersion (solution 1 or solution 2 in Example 1), the luminous efficiency of the resulting glass was measured by changing the gelation time. The glass phosphor was produced by the method described in Example 3 except for the amount of water.

When water is in a molar ratio of 8, 12, 17, 25, 34, 40 with respect to the total amount of zirconia and silica, the time until gelation is 2 minutes and 5 minutes for both green and red light emission, 10 minutes, 15 minutes, 20 minutes and 25 minutes. The reaction was further promoted from the gel state to cause vitrification, and the luminous efficiency was measured. The result is shown in FIG.

  From FIG. 7, in both the green light emitting glass phosphor and the red light emitting glass phosphor, the light emission efficiency is maintained at the value of the cadmium telluride aqueous solution used at the time of preparation in the range where the gelation time does not exceed 20 minutes. When it exceeded, it turned out that luminous efficiency falls. Thereby, it became clear that the luminous efficiency of the nanoparticle-dispersed aqueous solution can be substantially maintained by controlling the time until gelation within a certain time.

Example 5
The red light emitting silica zirconia glass phosphor obtained from the solution 2 in Example 3 was examined for stability against boiling water. The result is shown in FIG.

In FIG. 8, after 1 hour of immersion in boiling water, the initial absorption and emission spectra of the nanoparticles were not changed, and the luminous efficiency was maintained at 60%. The luminous efficiency changed from 60% to 56% only after 3 hours, but the absorption spectrum hardly changed. After 1 hour and 3 hours after immersion, the absorption spectra are almost the same, and are shown overlapping in FIG.

  Although not shown in FIG. 8, it was found that the glass phosphor obtained in Comparative Example 1 deteriorated in surface in about 1 minute when placed in boiling water, and there was a marked difference.

Example 6
A nanoparticle-dispersed glass phosphor having tetrafunctional silica and titania as a matrix was produced.

  A red light emitting cadmium telluride nanoparticle dispersed aqueous solution (solution 1) was prepared in the same manner as in Example 1.

TEOS, pure water, and ethanol were mixed at a molar ratio of 1: 1: 1.8. A small amount of hydrochloric acid was added to adjust the pH of the solution to 4, and the mixture was stirred for 1 hour to partially hydrolyze TEOS.

Titanium tetraisopropoxide (Ti (OCH (CH ₃ ) ₂ ) ₄ ) and an equal volume of ethanol solution were added dropwise to the TEOS partially hydrolyzed solution prepared above, and the mixture was further heated and stirred at 70 ° C. for 20 minutes. The molar ratio of silicon to titanium in the solution was adjusted to 90:10. After cooling to room temperature, hydrochloric acid diluted with pure water was added dropwise. At this time, the molar ratio of (titanium + silicon): water: hydrochloric acid was adjusted to 1: 5: 0.002. This solution was stirred for 2 hours, and most of ethanol was removed to obtain a hydrolysis solution.

3 ml of this hydrolyzed solution was taken out on a Teflon petri dish, 6 ml of water was added, and then adjusted to pH 7 with a 0.1 M sodium hydroxide solution. To this, the previous solution 1 was added with stirring, and then allowed to stand in this state for 3 days to obtain a transparent glass phosphor.

  The luminous efficiency of this phosphor was measured and showed a very high value of 62%.

The photograph and schematic diagram of the silica zirconia glass phosphor obtained in Example 3 are shown. 2 is a graph showing emission and absorption spectra of green light emission and red light emission semiconductor nanoparticle-dispersed silica glass phosphors obtained in Example 1 and emission spectra of solutions 1 and 2; 4 is a graph showing changes in absorption and emission spectra before and after heat treatment (80 ° C., 3 hours, in the air) of the red light-emitting glass phosphor obtained in Example 1. (A) is a graph which shows the absorption and emission spectrum of the green light emission glass fluorescent substance obtained in Example 2. FIG. (B) is a graph which shows the relationship between the nanoparticle dispersion density | concentration in the green light emission glass fluorescent substance obtained in Example 2, and luminous efficiency. 4 is a graph showing the relationship between the nanoparticle dispersion concentration and the light emission efficiency of the green light emitting silica zirconia glass (Si _0.93 Zr _0.07 O ₂ ) phosphor obtained in Example 3. 4 is a graph showing the relationship between the nanoparticle dispersion concentration and the luminous efficiency of the red light emitting silica zirconia glass (Si _0.93 Zr _0.07 O ₂ ) phosphor obtained in Example 3. It is a graph which shows the relationship between the gelation time in the green light emission and red light emission silica zirconia glass fluorescent substance obtained in Example 4, and luminous efficiency. Is a graph showing the immersion time and the absorption and relationships of the emission spectrum of the boiling water was obtained in Example 5 red luminescent silica zirconia glass _{(Si 0.93 Zr 0.07 O 2)} .

Claims (11)

A phosphor in which semiconductor nanoparticles with a luminous efficiency of 25% or more are dispersed in an inorganic matrix. The phosphor according to claim 1, wherein the semiconductor nanoparticles are dispersed in an inorganic matrix at a concentration of 10 ⁻⁵ mol / liter or more. The phosphor according to claim 1 or 2, having a Vickers hardness of 500 MPa or more. The phosphor according to claim 1, 2 or 3, having a specific gravity of 1.7 or more. The phosphor according to any one of claims 1 to 4, wherein the inorganic matrix is produced by a sol-gel method using a metal alkoxide. The phosphor according to claim 5, wherein the metal alkoxide is at least one selected from the group consisting of tetraalkoxysilane, tetraalkoxyzirconium, tetraalkoxytitanium, and trialkoxyaluminum. The phosphor according to any one of claims 1 to 6, wherein the semiconductor nanoparticles are at least one selected from the group consisting of cadmium selenide, cadmium telluride, cadmium sulfide and zinc selenide. A light emitting device comprising the phosphor according to claim 1. The light emitting device according to claim 8, further comprising a cooling device or a heat radiation material for maintaining the temperature of the glass phosphor at 50 ° C. or lower. A method for producing a phosphor in which semiconductor nanoparticles having a luminous efficiency of 25% or more are dispersed in an inorganic matrix, wherein (1) a metal alkoxide, alcohol, water and acid are mixed to obtain a hydrolyzed solution of metal alkoxide, (2) After removing most of the alcohol from the hydrolysis solution, and (3) further adjusting the pH to 5.5 to 8.5, (4) a dispersion of semiconductor nanoparticles having a luminous efficiency of 25% or more, and And then curing the phosphor. The method for manufacturing a phosphor according to claim 10, further comprising heat-treating the phosphor after curing in (4).

Images