JP2007146154A - Wavelength converter, lighting system, and lighting system assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wavelength converter which uses a semiconductor material consisting of a composition excellent in safety as a replacement of cadmium selenide (CdSe) and has a equivalent to or higher level of conversion efficiency than those converters using CdSe. <P>SOLUTION: The wavelength converter has phosphor particles dispersed in a transparent matrix, converts the wavelength of the light emitted from a light source, and outputs the output light containing the light whose wavelength is converted. The phosphor comprises an Ag element a group III element consisting of indium or gallium and sulfur, and contains semiconductor fine particles which are substantially free of Cd or Se. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wavelength converter in which a phosphor including semiconductor fine particles is dispersed in a matrix, an illuminating device that converts the wavelength of light emitted from a light-emitting element to the outside in the wavelength converter, and the illuminating device And a plurality of lighting device assemblies. In particular, the present invention relates to an illumination wavelength converter and an illumination device that are preferably used for a backlight power source for an electronic display or a fluorescent lamp.

  A light emitting element made of a semiconductor material (hereinafter sometimes referred to as “LED chip”) is small in size, has high power efficiency, and vividly develops color. LED chips have excellent characteristics such as long product life, strong on / off lighting repeatability, and low power consumption, so they are expected to be applied to backlight sources such as liquid crystals and lighting sources such as fluorescent lamps. Has been.

  The application of the LED chip to the light emitting device is that the wavelength of part of the light of the LED chip is converted with a phosphor, and the wavelength-converted light and the light of the LED that is not wavelength-converted are mixed and emitted, thereby It has already been manufactured as a light emitting device that emits a color different from that of light.

Specifically, a light emitting device has been proposed in which a wavelength converter including a phosphor is provided on the surface of an LED chip in order to emit white light. For example, in a light emitting device in which a wavelength converter including a YAG phosphor expressed by a composition formula of (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ is formed on a blue LED chip using an nGaN-based material, Since blue light is emitted from the LED chip and a part of the blue light is changed to yellow light by the wavelength converter, a light-emitting device in which blue and yellow light are mixed and white is proposed (Patent Document 1 and 2).

  An example of such a light emitting device is shown in FIG. According to FIG. 4, the light emitting device includes a light emitting element 103 including a semiconductor material that emits light having a center wavelength of 470 nm on a substrate 102 on which an electrode 101 is formed, and a wavelength provided so as to cover the light emitting element 103. The wavelength converter 104 contains a phosphor 105. If desired, a reflector 106 that reflects light may be provided on the side surfaces of the light emitting element 103 and the wavelength converter 104 so that light escaping to the side surface is focused forward to increase the intensity of the output light.

  In this light emitting device, when the phosphor 105 is irradiated with light emitted from the light emitting element 103, the phosphor 105 is excited to emit visible light, and this visible light is used as an output. However, when the brightness of the light emitting element 103 is changed, the light quantity ratio between blue and yellow changes, so that there is a problem that the color tone of white changes and the color rendering property is inferior.

  Therefore, in order to solve such a problem, a purple LED chip having a peak of 400 nm or less is used as the light emitting element 103 in FIG. 5, and three types of phosphors 115, 116, and 117 are provided in the wavelength converter 104. It has been proposed to employ a structure mixed in a molecular resin and to convert white light into red, green and blue wavelengths to emit white light (see Patent Document 3). Thereby, a color rendering property can be improved.

However, in the light emitting device described in Patent Document 3, the luminous efficiency of a red component phosphor (for example, Y ₂ O ₃ S: Eu) in the ultraviolet region near 400 nm of excitation light is significantly higher than other phosphors. Due to the low level, there is a problem that white light with a good emission balance of red, green and blue cannot be obtained.
Therefore, if the amount of the red phosphor with low luminous efficiency is increased, the fluorescence emitted from the green and blue phosphors is reabsorbed by the red phosphor, so that the emission amounts of the green and blue phosphors can be kept low. As a result, there is a problem that the luminous efficiency of the white light emitting device is not improved. Further, the efficiency can be improved by increasing the mixing amount of the green and blue phosphors having high luminous efficiency, but there is a problem that it is impossible to obtain white light with a good emission balance of red, green and blue.

  Accordingly, there is a need for a photoluminescent phosphor having high fluorescence quantum efficiency in a wide wavelength range from blue to red. As means for meeting the demand, for example, Patent Documents 4 and 5 below propose to cope with the problem by making the photoluminescence phosphor into nanoparticles. Further, in 1994, Bhargava et al. Reported that the emission quantum efficiency of the doped phosphor increased when the particle radius became less than the Bohr radius (see Non-Patent Document 1).

  Since this announcement, various studies have been made on the light emission characteristics of nanoparticles, and as shown in Patent Documents 4 and 5, the light emission efficiency can be achieved by utilizing the quantum size effect that is manifested by making photoluminescence phosphors into nanoparticles. I will give you. Specifically, the luminous efficiency can be increased without changing the composition by changing the particle diameter of the photoluminescent phosphor from the conventional several μm to 0.1 nm to 100 nm.

However, in the Example of patent document 5, only what used cadmium selenide (CdSe) for the core as a photo-luminescence fluorescent substance composition is indicated.
CdSe has a band gap of about 2 eV, and it is possible to change the fluorescence wavelength by changing the particle diameter, but it is highly toxic and has industrial and environmental problems. In addition, in the specifications of Patent Documents 4 and 5, ZnS is exemplified as a phosphor composition that does not require Cd or Se, but phosphors composed of these compositions cannot exhibit luminous efficiency as high as CdSe. There is a problem.

Japanese Patent No. 2927279 JP 11-261114 A JP 2002-314142 A JP 2004-71908 A Japanese translation of PCT publication No. 2002-510866 R.N.Bhargava et al, "Optical Properties of Manganese-Doped Nanocrystals of ZnS" Phys. Rev. Lett. 72, 416 (1994)

  An object of the present invention is to provide a wavelength converter having a conversion efficiency equal to or higher than that of a converter provided with CdSe using a semiconductor material having a composition with excellent safety instead of toxic CdSe and the like. It is providing the illuminating device using a converter, and the illuminating device aggregate | assembly provided with two or more the illuminating devices.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained a wavelength that is less harmful and can efficiently convert light by using semiconductor fine particles made of Ag element, indium, sulfur, and the like. We have found that a transducer can be obtained and have completed the present invention.

That is, the wavelength converter, the lighting device, and the lighting device assembly in the present invention have the following characteristics.
(1) A wavelength converter in which a phosphor is dispersed in a transparent matrix, converts a wavelength of light emitted from a light source, and outputs output light including the light whose wavelength is converted, the phosphor Is a wavelength converter comprising semiconductor fine particles containing Ag element, Group III element of periodic table, and sulfur, and substantially free of Cd and Se.
(2) The wavelength converter according to (1), wherein the semiconductor fine particles further contain zinc.
(3) The semiconductor fine _{particles, Zn α Ag β InS γ (} α = 0.1~1, β = 0.1~1, γ = 2~4) according to claim 1 or 2, characterized in that a compound The described wavelength converter.
(4) The wavelength converter according to any one of (1) to (3), wherein the surface of the semiconductor fine particles is coated with a semiconductor material having a larger band gap than the semiconductor fine particles.
(5) The wavelength converter according to any one of (1) to (3), wherein the surface of the semiconductor fine particles is coated with a surface modifying molecule made of an organic compound.
(6) A semiconductor material having a larger band gap than the semiconductor fine particles and a surface modifying molecule made of an organic compound are sequentially laminated on the surface of the semiconductor fine particles (1) to (3) The wavelength converter in any one of.
(7) The wavelength converter according to (5) or (6), wherein the surface modifying molecule is a molecule having two or more silicon-oxygen bonds.
(8) The wavelength converter according to any one of (1) to (7), wherein an average particle diameter of the semiconductor fine particles is 0.5 to 10 nm.
(9) The wavelength converter according to any one of (1) to (8), wherein two or more phosphors including the semiconductor fine particles having different average particle diameters are dispersed.
(10) The wavelength converter according to any one of (1) to (9), wherein a peak wavelength of the output light is 400 to 750 nm.
(11) The wavelength converter according to any one of (1) to (10), wherein the wavelength converter has a thickness of 0.1 to 5 mm.
(12) A light-emitting element made of a compound semiconductor that emits excitation light and a wavelength converter that converts the wavelength of the excitation light are provided on a substrate, and the wavelength converter is any one of (1) to (11) An illumination device characterized by being a wavelength converter.
(13) The illumination device according to (12), wherein the band gap energy of at least part of the semiconductor fine particles included in the phosphor of the wavelength converter is smaller than the energy emitted by the light emitting element.
(14) A lighting device assembly comprising a plurality of lighting devices according to (12) or (13).

  According to said (1)-(3), Ag element, a periodic table group III element, sulfur, and zinc as needed are used for semiconductor fine particles. Therefore, it is not necessary to use highly harmful raw materials, and a highly safe wavelength converter can be realized with a highly safe semiconductor material. Moreover, since Ag element has high stability, the impurity level between bands can be reduced and very excellent quantum efficiency can be realized. As a result, it is possible to provide a wavelength converter having a conversion efficiency equal to or higher than that of a converter including CdSe without using CdSe. Such a wavelength converter is preferably used as a wavelength converter for illumination.

  According to the above (4), by coating the surface of the semiconductor fine particle with a semiconductor material having a larger band gap than the semiconductor fine particle, defects existing on the surface of the semiconductor fine particle can be reduced and the quantum confinement effect of the semiconductor fine particle can be reduced. Therefore, the quantum efficiency of the phosphor can be improved. As a result, a wavelength converter with excellent conversion efficiency can be realized.

  According to the above (5) and (6), the phosphor can be more uniformly dispersed by coating the surface of the semiconductor fine particles with the predetermined surface modifying molecule. As a result, a wavelength converter having excellent conversion efficiency can be obtained.

  According to the above (7), since the dispersibility of the phosphor with respect to the polymer resin, for example, the silicone-based polymer resin is improved, a wavelength converter with less unevenness in the output light can be obtained. In addition, a molecule having two or more silicon-oxygen bonds has a stronger silicon-oxygen bond than a carbon-carbon bond at this portion, and therefore is subject to decomposition by light or heat. Hateful. As a result, a wavelength converter excellent in light resistance, heat resistance and transparency can be obtained. Furthermore, since the molecule having two or more silicon-oxygen bonds repeatedly has water repellency, an effect of protecting the phosphor from deterioration due to moisture can be obtained.

  According to the above (8), by setting the average particle diameter to 0.5 to 10 nm, a phosphor with high fluorescence efficiency (semiconductor ultrafine particles) can be realized, and by dispersing the phosphor in the wavelength converter, A wavelength converter with very high conversion efficiency can be obtained.

  According to the above (9), since two or more kinds of phosphors having semiconductor fine particles having different average particle diameters are dispersed in the wavelength converter, the wavelength converter converts the light into a plurality of wavelengths. A wide wavelength range can be covered. As a result, if this wavelength converter is provided, a light emitting device having excellent color rendering properties can be obtained.

  According to the above (10), since the peak wavelength of the output light emitted from the wavelength converter is 400 to 750 nm, a wide wavelength range can be covered, so that the color rendering can be improved.

  According to the above (11), by setting the thickness of the wavelength converter to 0.1 to 5 mm, it is possible to improve the wavelength conversion efficiency by the phosphor and that the converted light is absorbed by the other phosphor. Can be suppressed. As a result, if this wavelength converter is provided, a highly efficient illumination device can be obtained.

  According to said (12), since the said wavelength converter is provided, the illuminating device excellent in safety | security, color rendering property, and luminous efficiency can be provided.

  According to the above (13), by making the band gap energy of at least a part of the semiconductor fine particles smaller than the energy emitted by the light emitting elements, the energy emitted by the light emitting elements can be efficiently absorbed by the semiconductor fine particles. The light emission efficiency of the light emitting device can be further improved.

  According to the above (14), since a plurality of the lighting devices are provided, a lighting device assembly excellent in safety, color rendering and luminous efficiency can be obtained, and it is a very bright and energy-saving alternative to the conventional fluorescent lamp. A lighting device assembly can be realized.

(Light emitting device)
The wavelength converter and light-emitting device of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an embodiment of a light emitting device of the present invention. The light-emitting device of the present invention includes a light-emitting element 3 made of a compound semiconductor that emits excitation light, a conductor 1 that is electrically connected to the light-emitting element and connected to the outside, and a wavelength that converts the wavelength of the excitation light. A converter 4 is provided on the substrate 2. The wavelength converter 4 includes phosphors 5 dispersed in a transparent matrix, converts the wavelength of light emitted from the light emitting element 3 as a light source, and outputs output light including the light whose wavelength has been converted. . In addition, the light-emitting device of FIG.

  FIG. 2 shows another embodiment of the light emitting device according to the present invention. As shown in FIG. 2, an inner layer 10 that covers the light emitting element 3 may be provided. The inner layer 10 can be formed of, for example, the transparent matrix shown below, and is preferably formed of a silicone resin.

(conductor)
The conductor 1 has a function as a conductive path for electrically connecting the light emitting element 3 and is connected to the light emitting element 3 with a conductive bonding material. As the conductor 1, for example, a metallized layer containing metal powder such as W, Mo, Cu, and Ag can be used. When the substrate 2 is made of ceramics, the conductor 1 is formed by firing a metal paste made of tungsten (W), molybdenum (Mo) -manganese (Mn), or the like on the upper surface of the substrate 2 at a high temperature. , Lead terminals made of copper (Cu), iron (Fe) -nickel (Ni) alloy or the like are molded and fixed inside the substrate 2.

(substrate)
Since the substrate 2 is required to have excellent thermal conductivity and high total reflectance, for example, a polymer resin in which metal oxide fine particles are dispersed is suitably used in addition to a ceramic material such as alumina or nitrogen aluminum. It is done.

(Light emitting element)
The light-emitting element 3 uses a light-emitting element including a semiconductor material that emits light having a center wavelength of 450 nm or less because the phosphor can be efficiently excited.
In particular, it is preferable to emit light of 380 to 420 nm. Thereby, it is possible to increase the intensity of the output light and obtain a lighting device with higher emission intensity.

The light-emitting element 3 preferably emits the above-mentioned center wavelength, but having a structure (not shown) having a light-emitting layer made of a semiconductor material on the surface of the light-emitting element substrate has a high external quantum efficiency. preferable. Examples of such semiconductor materials include various semiconductors such as ZnSe and nitride semiconductors (GaN, etc.), but the type of the semiconductor material is not particularly limited as long as the emission wavelength is in the above wavelength range. A stacked structure including a light-emitting layer made of a semiconductor material may be formed over a light-emitting element substrate using a crystal growth method such as a metal organic chemical vapor deposition method (MOCVD method) or a molecular beam epitaxial growth method. In order to form a nitride semiconductor with good crystallinity with high productivity, for example, when a light emitting layer made of a nitride semiconductor is formed on the surface of the light emitting element substrate, sapphire, spinel, SiC, Si, ZnO, ZrB ₂ , GaN In addition, materials such as quartz are preferably used.

  In addition, it is preferable that the band gap energy of at least a part of the phosphor 5 included in the wavelength converter 4 is smaller than the energy emitted by the light emitting element 3. With such a configuration, energy emitted from the light emitting element 3 can be efficiently absorbed by the phosphor 5, so that the light emission efficiency can be improved.

(Reflective member)
Reflective members 6 that reflect light are provided on the side surfaces of the light emitting element 3 and the wavelength converter 4 as necessary, and the light escaping to the side surfaces can be reflected forward to increase the intensity of the output light. Examples of the material of the reflecting member 6 include aluminum (Al), nickel (Ni), silver (Ag), chromium (Cr), titanium (Ti), copper (Cu), gold (Au), iron (Fe), and these. These laminated structures and alloys, ceramics such as alumina ceramics, or resins such as epoxy resins can be used.

(Wavelength converter)
The wavelength converter 4 contains a phosphor 5 having semiconductor fine particles in a transparent matrix. The phosphors 5 are directly excited by the light emitted from the light emitting element 3, respectively, and generate visible light as converted light. The converted light converted by the phosphor 5 in the wavelength converter 4 is synthesized and extracted as output light.

  The thickness of the wavelength converter 4 is 0.1 to 5.0 mm, preferably 0.2 to 1 mm, from the viewpoint of conversion efficiency. When the phosphor 5 having an average particle diameter of 0.5 to 10 μm is used, it is preferable that the thickness of the wavelength converter 4 is 0.3 to 1.0 mm. In the case of phosphor 5 having a particle diameter of 20 nm or less (phosphor 5 having semiconductor ultrafine particles), the wavelength converter 4 has a thickness of 0.1 to 1 mm, particularly 0.1 to 0.5 mm. preferable. If the thickness is within this range, the wavelength conversion efficiency by the phosphor 5 can be improved, and the converted light can be suppressed from being absorbed by other phosphors. As a result, the light emitted from the light emitting element 3 can be converted into visible light with high efficiency, and the converted visible light can be transmitted to the outside with high efficiency.

  The peak wavelength of the output light converted in the wavelength converter 4 is preferably 400 to 750 nm, particularly 450 to 650 nm. Thereby, the emission wavelength can be covered in a wide range, and the color rendering can be improved.

  The wavelength converter 4 contains a plurality of phosphors 5 and is directly excited by the light emitted from the light emitting element 3 to synthesize the wavelengths of these lights, covering the emission wavelength in a wide range and greatly improving the color rendering. Can be improved. The peak wavelength of the visible light thus obtained is preferably 400 to 750 nm, particularly 450 to 700 nm, particularly 500 to 650 nm.

  Since the wavelength converter 4 covers the emission wavelength in a wide range and can further improve the color rendering, it is desirable to emit fluorescence having two or more intensity peaks in the wavelength range of visible light. In addition, for example, it is preferable that a plurality of phosphors 5 having different conversion wavelengths are contained, and the conversion wavelengths include wavelengths corresponding to blue, green, yellow, and red.

(Transparent matrix)
Since the wavelength converter 4 can uniformly disperse and carry the phosphor 5 and can suppress light deterioration of the phosphor 5, it is formed by being dispersed in a transparent matrix such as a polymer resin or a glass material. Is preferred. As a glass material such as a polymer resin film or a sol-gel glass thin film, a material having high transparency and durability that is not easily discolored by heating or light is desirable.

  The material of the polymer resin film is not particularly limited. For example, epoxy resin, silicone resin, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, cellulose acetate, polyarylate, Derivatives of these materials are used. In particular, it is preferable to have excellent light transmittance in a wavelength region of 350 nm or more. In addition to such transparency, a silicone resin is more preferably used from the viewpoint of heat resistance.

  Examples of the glass material include silica, titania, zirconia, and composite materials thereof. Each of the phosphors 5 is formed in a glass material by dispersing it alone. Compared to a polymer resin film, it has a high durability against light, particularly ultraviolet light, and further has a high durability against heat, so that the product life can be extended. In addition, since the glass material can improve stability, a light-emitting device with excellent reliability can be realized.

(Phosphor)
The phosphor 5 used in the present invention includes semiconductor fine particles containing Ag element, Group III elements of periodic table such as indium and gallium, and sulfur, or semiconductor fine particles further containing zinc. Therefore, it is not necessary to use highly harmful raw materials such as Cd and Se, and the wavelength converter 4 excellent in safety can be realized by using a semiconductor material having a composition excellent in safety. In addition, since Ag element is highly stable, the impurity level between bands can be reduced in the obtained semiconductor fine particles compared to the case where other metal materials are used, thus realizing extremely excellent quantum efficiency. it can. Therefore, the wavelength converter 4 that can efficiently convert the excitation light from the light emitting element and has a conversion efficiency equal to or higher than that of the converter provided with CdSe is obtained.

  In this invention, it is preferable that 2 or more types of fluorescent substance 5 provided with the semiconductor fine particle from which an average particle diameter differs is used as the fluorescent substance 5. With this configuration, if two or more kinds of semiconductor fine particles having different average particle diameters are dispersed and mixed in the wavelength converter 4, they are converted into light of a plurality of wavelengths in the wavelength converter 4. A light emitting device that can be covered and has excellent color rendering is obtained.

  The average particle diameter of the semiconductor fine particles is preferably 0.5 to 10 nm. If the average particle diameter is 0.5 nm or more, the semiconductor ultrafine particles and the phosphor 5 having high fluorescence efficiency can be obtained because the efficiency of the semiconductor ultrafine particles can be suppressed from being reduced by the influence of surface defects. If the average particle size is 10 nm or less, light absorption and light emission can be repeated quickly. As a result, semiconductor ultrafine particles and phosphor 5 having excellent fluorescence efficiency can be obtained. In addition, the semiconductor ultrafine particles exhibit various light emission from red (long wavelength) to blue (short wavelength) by changing the size of the particles, and there is no limitation on the excitation wavelength as long as the energy is higher than the band gap. In addition, the emission lifetime is 100,000 times shorter than that of rare earth, and the absorption and emission cycles are repeated quickly, so that extremely high luminance can be achieved, and there is less deterioration than organic dyes (the number of photons that appear as fluorescence before deterioration) Is about 100,000 times that of the pigment). Therefore, if the semiconductor ultrafine particles are used, it is possible to realize the wavelength converter 4 and the light emitting device that have excellent luminous efficiency and have a long lifetime. That is, in the wavelength converter 4, the phosphor 5 may be a combination of phosphors including semiconductor fine particles having different conversion wavelengths.

  The surface of the semiconductor fine particles may be coated with a semiconductor material having a larger band gap than the semiconductor fine particles. According to this configuration, defects existing on the surface of the semiconductor fine particles can be reduced, and the quantum confinement effect of the semiconductor fine particles is increased. As a result, the quantum efficiency of the semiconductor fine particles is improved, and the wavelength converter 4 having excellent conversion efficiency is obtained. In the present invention, examples of the semiconductor material used for coating include ZnS, ZnO, MgS, GaN, and GaP.

  An example of coating the surface of the semiconductor fine particles with a semiconductor material having a larger band gap than the semiconductor fine particles includes a so-called core-shell structure composed of an inner core (core) and an outer shell (shell). The core-shell type semiconductor ultrafine particles having such a structure may be suitable for applications using an exciton absorption / emission band. In this case, it is generally effective to form an energy barrier by using a shell semiconductor particle having a larger band gap (forbidden band width) than that of the core. This is presumed to be due to a mechanism that suppresses the influence of an undesirable surface level or the like due to the influence of the outside world or crystal lattice defects on the crystal surface. Although the composition of the semiconductor material suitably used for the shell depends on the band gap of the core semiconductor crystal, the bulk band gap is 2.0 eV or more at a temperature of 300 K, such as ZnS, ZnO, MgS, GaN, GaP or the like is preferably used.

  The semiconductor fine particles may be coated with surface modifying molecules made of an organic compound (for example, an organic ligand). Thus, if it coat | covers with a surface modification molecule | numerator, the characteristic deterioration by aggregation of particle | grains can be suppressed. Specifically, due to the steric hindrance of the surface modifying molecule, the phosphor 5 can be dispersed while maintaining a certain distance without bringing the particles close to each other. When dispersed in this way, the wavelength converter 4 can suppress the deterioration of characteristics due to aggregation of the phosphors 5 and can exhibit the functions of the semiconductor fine particles and the phosphors 5 to the maximum, and has excellent conversion efficiency. Is obtained.

  As the surface modifying molecule, n-propyl group, isopropyl group, n-butyl group, isobutyl group, n-pentyl group, cyclopentyl group, n-hexyl group, cyclohexyl group, octyl group, decyl group, dodecyl group, hexadecyl group, Examples include molecules having a hydrocarbon group containing an aromatic hydrocarbon group such as an alkyl group having about 3 to 20 carbon atoms such as an octadecyl group, a phenyl group, a benzyl group, a naphthyl group, and a naphthylmethyl group. Molecules having a linear alkyl group having about 6 to 16 carbon atoms such as a hexyl group, octyl group, decyl group, dodecyl group, hexadecyl group and the like are more preferable. Also, sulfur atom-containing functional groups such as mercapto group, disulfide group, thiophene ring, nitrogen atom-containing functional groups such as amino group, pyridine ring, amide bond, nitrile group, carboxyl group, sulfonic acid group, phosphonic acid group, phosphinic acid A molecule having an acidic functional group such as a group, a phosphorus atom-containing functional group such as a phosphine group or a phosphine oxide group, or an oxygen atom-containing functional group such as a hydroxy group, a carbonyl group, an ester bond, an ether bond, or a polyethylene glycol chain, It may be used as a surface modifying molecule. These surface-modifying molecules are preferably used because they can be dispersed at a certain distance without bringing the phosphors 5 close to each other due to steric hindrance of the surface-modifying molecules.

  The surface modifying molecule may be a molecule having two or more silicon-oxygen bonds, for example, a silicone mainly having a silicon-oxygen bond and a functional group selected from an amino group, a carboxyl group, a mercapto group, and a hydroxy group. System compounds may be used. When such a surface modification molecule is used, it is preferable that the transparent matrix is a silicone resin mainly composed of a silicon-oxygen bond, and the phosphor 5 is dispersed in the silicone resin. With these configurations, the dispersibility of the phosphor 5 with respect to a polymer resin, for example, a silicone-based polymer resin is improved, and the wavelength converter 4 having excellent conversion efficiency, light resistance, heat resistance, and transparency can be obtained. .

  FIG. 3 shows a configuration example of the phosphor 5 and the semiconductor fine particles. As shown in FIG. 3, the phosphor 5 includes semiconductor fine particles 20, and a semiconductor material 21 and surface modification molecules 25 are sequentially stacked on the surface of the semiconductor fine particles 20. The surface of the semiconductor fine particles 20 may be covered only with the semiconductor material 21 or may be covered only with the surface modifying molecules 25. However, the surface of the semiconductor fine particle 20 is preferably covered with both the semiconductor material 21 and the surface modification molecule 25, and the semiconductor material 21 and the surface modification molecule 25 are sequentially laminated as shown in FIG. Is more preferable.

(Preparation of semiconductor fine particles)
The semiconductor fine particles and the semiconductor ultra fine particles can be produced, for example, by the production method shown below. For example, gas phase chemical reaction methods such as flame process, plasma process, electric heating process, laser process, physical cooling method, sol-gel method, alkoxide method, coprecipitation method, hot soap method, hydrothermal synthesis method, spray pyrolysis method, etc. The liquid phase method, the mechanochemical bonding method, and the like can be used. Moreover, when producing the semiconductor fine particles used in the present invention, it is preferably produced by a hot soap method.
The average particle size can be measured using a method in which the average particle size of the semiconductor ultrafine particles (yellow phosphor 5a, red phosphor 5b) is measured in Examples described later.

(Production of wavelength converter)
The wavelength converter 4 can be formed by a coating method using a glass material such as a sol-gel glass film or a polymer resin film. Although it will not be limited if it is a general coating method, the application | coating by a dispenser is preferable. For example, it can be manufactured by mixing the phosphor 5 with a liquid uncured resin, a glass material, or a resin and a glass material plasticized with a solvent. As the uncured resin, for example, a silicone resin can be used. These resins may be of a type that is cured by mixing two liquids, or a type that is cured by one liquid. The body 5 may be kneaded, or the phosphor 5 may be kneaded in one of the liquids. In addition, as a resin made plastic with a solvent, for example, an acrylic resin can be used.

  The cured wavelength converter 4 can be obtained by forming into a film shape by using a coating method such as a dispenser in an uncured state, or pouring into a predetermined mold and hardening. As a method of curing the resin and the glass material, there are a method of using heat energy and light energy, and a method of volatilizing the solvent.

(Production of light emitting device)
The light emitting device of the present invention can be obtained by installing the wavelength converter 4 on the light emitting element 3 as shown in FIGS. As a method of installing the wavelength converter 4 on the light emitting element 3, it is possible to install the cured sheet-like wavelength converter 4 on the light emitting element 3, and a liquid uncured material is applied on the light emitting element 3. It is also possible to harden and install after installation.

(Lighting device assembly)
The illumination device assembly of the present invention comprises a plurality of the illumination devices. Therefore, a lighting device assembly excellent in safety, color rendering properties and luminous efficiency can be obtained, and a very bright and power saving lighting device assembly can be obtained. For example, an illuminating device assembly having a configuration in which a plurality are arranged in the same plane is preferable.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited only to a following example.

[Example 1]
(Preparation of semiconductor ultrafine particles)
The semiconductor ultrafine particles shown in Table 1 were produced by the following method by the hot soap method. First, a predetermined amount of silver chloride (manufactured by Kanto Chemical Co., Inc.) and a predetermined amount of indium chloride (manufactured by Kanto Chemical Co., Ltd.) were each dissolved in oleylamine. Next, the solutions 1 were prepared by mixing the respective solutions. Next, 7.6 g (0.1 M) of zinc diethyldithiocarbamate (manufactured by Kanto Chemical Co., Inc.) was dissolved in a mixed solution of oleylamine and trioctylphosphine to prepare solution 2. Solution 1 and solution 2 were adjusted in nitrogen. The amounts of silver chloride and indium chloride were added so that the charging ratio (molar ratio) described in Table 1 was obtained.

The solution 1 and the solution 2 prepared by the above method are mixed and stirred, and the semiconductor ultrafine particles (Zn _α Ag _β InS _γ (α) are reacted at the reaction temperature (° C.) and reaction time (hour) shown in Table 1. = 0.1 to 1, β = 0.1 to 1, γ = 2 to 4) Note that the charging ratio (molar ratio) of silver, indium and sulfur, reaction temperature, and reaction time are changed. (See Table 1), the average particle size of the semiconductor ultrafine particles was controlled, and after the reaction, this solution was cooled to room temperature, and toluene was further added to the cooled solution and mixed uniformly. In addition, the semiconductor ultrafine particles were precipitated by applying an acceleration of 1500 G for 10 minutes with a centrifuge.
The average particle diameter of the semiconductor ultrafine particles (yellow phosphor 5a, red phosphor 5b) was measured using a transmission electron microscope (TEM). The results are shown in Table 1.
The transmission electron microscope used was JEOL JEM2010F, and an acceleration voltage of 200 kV was observed according to the following procedure. The semiconductor ultrafine particles precipitated as described above were taken in a sample bottle, and IPA or toluene in an amount such that the particle concentration was in the range of 0.002 to 0.02 mol / liter was added and dispersed. This was scooped with a microgrid for TEM observation, dried, and set in a transmission electron microscope. The average particle diameter was measured by confirming the particles from the lattice image. First, the part where the particles adhered to the mesh was searched at a low magnification. At this time, the portion where a lot of ultrafine semiconductor particles are attached is not suitable for measuring the average particle diameter because the particles overlap in the direction of the electron beam. Also, the semiconductor ultrafine particles adhering to the Cu mesh part of the microgrid are not suitable for observation of the average particle diameter because the lattice image cannot be observed. Therefore, the semiconductor ultrafine particles for measuring the average particle diameter were selected by selecting a portion having as little overlap as possible in the resin portion of the microgrid. Next, this portion is enlarged to about 1,000,000 times to confirm the lattice image.
At this time, if a large amount of organic components used in the synthesis remain around the semiconductor ultrafine particles, the lattice image is blurred, so that the average particle diameter cannot be measured correctly. In such a case, observation was performed by changing the location, or in some cases, a sample was prepared by repeatedly removing organic components during synthesis, and observation was performed.
Removal of organic components during synthesis is achieved by adding chloroform, toluene, or hexane to the precipitated semiconductor ultrafine particles and dispersing with ultrasound, then adding alcohol (for example, ethanol) to this and centrifuging it. Can be done. Organic components at the time of synthesis are dissolved in the supernatant ethanol, and the semiconductor ultrafine particles are precipitated. This operation was repeated as necessary. Thus, after searching for semiconductor ultrafine particles with less organic component adhesion used during synthesis, a lattice image was photographed at a magnification of 4,000,000. At this time, if the electron beam was kept on for a long time, the semiconductor ultrafine particles moved, and thus the image was taken promptly.
The average particle diameter of the semiconductor ultrafine particles was determined by processing according to the following method based on the diameter of 200 captured lattice images.
The length average diameter was calculated by statistically processing the diameter of the measured lattice image using a histogram. The length average diameter was calculated by counting the number belonging to the diameter section and dividing the sum of the product of the center value and the number of the diameter section by the total number of the measured grid images (average (Refer to "Ceramic manufacturing process" p.11-12, edited by the Ceramic Industry Association Editorial Committee Lecture Subcommittee). The length average diameter thus calculated was regarded as the average particle diameter of the semiconductor ultrafine particles.

[Comparative Example 1]
In the same manner as in Example 1, cadmium selenide (CdSe) semiconductor ultrafine particles having an average particle size (2 nm, 2.9 nm, 4.7 nm, 120 nm) were produced by a hot soap method.
7.9 g (0.1 M) Se powder manufactured by Kanto Chemical Co. was dissolved in 250 g of trioctylphosphine (TOP), and this was designated as Solution 1. Next, 7.6 g (0.1 M) sodium sulfide manufactured by Kanto Chemical Co., Inc. was dissolved in 250 g of trioctylphosphine (TOP) to prepare Solution 2.
Next, 5.3 g (0.02 M) of cadmium acetate manufactured by Kanto Chemical Co., Ltd. and 100 g of stearic acid were mixed and dissolved at 130 ° C. 400 g of trioctylphosphine oxide (TOPO) was added to this solution and heated to 300 ° C. to dissolve.
The solution 1 was added to this solution and allowed to react at 300 ° C. After completion of the reaction, the mixture was cooled to room temperature, 200 g of toluene was further added to the cooled solution, and the mixture was uniformly mixed. Then, ethanol was further added, and acceleration of 1500 G was performed with a centrifuge for 10 minutes to precipitate cadmium selenide particles. I let you. Next, 3.7 g (0.02 M) of zinc acetate and 100 g of stearic acid were mixed with the cadmium selenide particles and dissolved at 130 ° C. 400 g of trioctylphosphine oxide (TOPO) was added to this solution, heated to 300 ° C., solution 2 was added, and then cooled to room temperature. 200 g of toluene is added and mixed uniformly, and then ethanol is further added, and the core-shell structured cadmium selenide particles coated with zinc sulfide are precipitated by accelerating at 1500 G for 10 minutes in a centrifuge. did.

[Examples 2 to 11]
(Formation of core-shell structure)
The surface of the semiconductor ultrafine particles of Example 1 was coated with a semiconductor material (zinc sulfide (ZnS)) by the following method to form a core-shell structure. First, the semiconductor ultrafine particles obtained by the above method were added to a mixed solution of 1.1 g of zinc acetate, 9.9 mL of oleic acid and 300 mL of octadecene, and heated and stirred at 170 ° C. for 2 hours under argon flow conditions. To this solution, 1.5 g of sulfur 12 g / trioctylphosphine (TOP) was added and stirred at 300 ° C. After completion of the reaction, the mixture was cooled to room temperature, 200 g of toluene was added and mixed uniformly, ethanol was further added, and acceleration was applied at 1500 G for 10 minutes with a centrifuge to form a core-shell structure whose surface was coated with zinc sulfide. The semiconductor ultrafine particles were precipitated.

(Formation of surface modification molecules)
Each of the semiconductor ultrafine particles of Example 1, the core ultrafine semiconductor particles (Examples 2 to 12), and the semiconductor ultrafine particles of Comparative Example 1 (1 g) has an amino group as a functional group, and the side 2 g of a modified silicone whose chain substituent is a methyl group was added, and the mixture was heated and stirred at 40 ° C. for 8 hours in a nitrogen atmosphere. Subsequently, 2 g of toluene was added to the liquid obtained by the above method and stirred, and then 10 g of methanol was added thereto. After confirming the white turbidity, the semiconductor ultrafine particles were precipitated by applying an acceleration of 1500 G for 30 minutes with a centrifuge. Thereafter, the supernatant toluene and methanol solution were removed with a spoid. This operation was repeated three times to remove excess modified silicone to obtain semiconductor ultrafine particles (phosphor) coated with amino group-substituted modified silicone. The state of coating with the modified silicone was confirmed by Fourier transform infrared spectroscopic analysis and further by X-ray photoelectron spectroscopic analysis. Table 1 shows the fluorescence wavelength (light emission characteristics) of the semiconductor ultrafine particles synthesized by the above method.

結果を表１に示す。 (Measurement of quantum efficiency)
The quantum efficiency of the obtained phosphor was measured by a method in which a reference substance (rhodamine B) having a known quantum efficiency was prepared and obtained by relative comparison with the reference substance as described below.
(Quantum efficiency measurement method)
(1) Dissolve phosphor and reference substance in toluene. At this time, the concentration of each solution was adjusted so that the absorbance was 0.2 at the emission wavelength (wavelength 395 nm) of the light-emitting element.
(2) Each adjusted solution was diluted 10 times with toluene, and luminescence characteristics were measured with a fluorimeter manufactured by Shimadzu Corporation. The excitation wavelength was 395 nm.
(3) Each fluorescence spectrum area was determined. Using each area, the quantum efficiency of the phosphor was determined according to the following formula.

The results are shown in Table 1.

  According to Table 1, it can be seen that all the phosphors (Examples 1 to 12) obtained by the above method exhibited a quantum efficiency of 70% or more.

(Mounting of light emitting elements)
The light-emitting device includes (1) an n-type GaN layer that is an undoped nitride semiconductor, (2) a GaN layer that is formed with an Si-doped n-type electrode and serves as an n-type contact layer, and (3) an undoped device. The n-type GaN layer, which is a nitride semiconductor, is stacked, and then (4) a GaN layer that forms a light emitting layer, (5) an InGaN layer that forms a well layer, and (6) a barrier layer A GaN layer (4) to (6) is used as one set, and a multi-quantum well structure in which five InGaN layers sandwiched between GaN layers are stacked. It mounted in the package which forms the board | substrate with which the wiring pattern for arrange | positioning this light emitting element was formed, and the frame-shaped reflection member surrounding near ultraviolet LED. A light emitting element was mounted on the wiring pattern in the package via an Ag paste.

(Production of inner layer)
Subsequently, the package was filled with a silicone resin to cover the light emitting element, and the resin was further cured by heating to form an inner layer. The silicone resin was filled by a coating method using a dispenser.

(Production of wavelength converter)
In 100 parts by weight of a silicone resin composed of a dimethyl silicone skeleton, 30 parts by weight of the phosphors of Examples 1 to 11 and Comparative Example 1 were dispersed and mixed to prepare a phosphor-containing resin paste. The obtained phosphor-containing resin paste was applied and formed on a smooth substrate with a dispenser, and this was heated on a hot plate at 150 ° C. for 5 minutes to prepare a temporarily cured film. Furthermore, this was heated in a dryer at 150 ° C. for 5 hours to produce a phosphor-containing film (wavelength converter). In addition, the thickness of the obtained fluorescent substance containing film (wavelength converter) was 0.5 mm.

(Production of light emitting device)
The phosphor-containing film was attached to the upper surface of the inner layer to obtain a light emitting device shown in FIG. Note that the obtained wavelength converter was formed by interposing the same silicone resin as the inner layer and the same material resin as an adhesive.

(Luminescence efficiency test)
The light emission efficiency of the light emitting device composed of each wavelength converter was measured using a light emission characteristic evaluation device manufactured by Otsuka Electronics Co., Ltd. As a result of the measurement, in Examples 1 to 11, lighting devices showing high luminous efficiency of 60 lm / W or more were obtained.

It is a schematic sectional drawing which shows embodiment of the wavelength converter and light-emitting device of this invention. It is a schematic sectional drawing which shows other embodiment of the wavelength converter and light-emitting device of this invention. It is a schematic sectional drawing which shows the example of the fluorescent substance used with the wavelength converter of this invention. It is a schematic sectional drawing which shows the conventional light-emitting device. It is a schematic sectional drawing which shows the conventional light-emitting device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductor 2 Substrate 3 Light emitting element 4 Wavelength converter 5 Phosphor 6 Reflecting member 20 Semiconductor fine particle 21 Semiconductor material 25 Surface modification molecule

Claims (14)

A phosphor in which a phosphor is dispersed in a transparent matrix, converts a wavelength of light emitted from a light source, and outputs an output light including the light whose wavelength is converted,
The wavelength converter characterized in that the phosphor includes Ag fine particles, Group III elements of the periodic table, and sulfur, and includes semiconductor fine particles that do not substantially contain Cd and Se.   The wavelength converter according to claim 1, wherein the semiconductor fine particles further contain zinc. 3. The wavelength according to claim 1, wherein the semiconductor fine particles are made of a Zn _α Ag _β InS _γ (α = 0.1-1, β = 0.1-1, γ = 2-4) compound. converter.   The wavelength converter according to claim 1, wherein the surface of the semiconductor fine particles is coated with a semiconductor material having a larger band gap than the semiconductor fine particles.   The wavelength converter according to any one of claims 1 to 3, wherein the surface of the semiconductor fine particles is coated with a surface modifying molecule made of an organic compound.   The semiconductor material which has a larger band gap than the said semiconductor fine particle, and the surface modification molecule | numerator which consists of an organic compound are laminated | stacked in order on the surface of the said semiconductor fine particle. Wavelength converter.   The wavelength converter according to claim 5 or 6, wherein the surface modification molecule is a molecule having two or more silicon-oxygen bonds.   The wavelength converter according to claim 1, wherein an average particle diameter of the semiconductor fine particles is 0.5 to 10 nm.   The wavelength converter according to any one of claims 1 to 8, wherein two or more kinds of phosphors including the semiconductor fine particles having different average particle diameters are dispersed.   The wavelength converter according to claim 1, wherein a peak wavelength of the output light is 400 to 750 nm.   The thickness of the said wavelength converter is 0.1-5 mm, The wavelength converter in any one of Claims 1-10 characterized by the above-mentioned.   A wavelength converter according to any one of claims 1 to 11, comprising a light emitting element made of a compound semiconductor that emits excitation light and a wavelength converter that converts the wavelength of the excitation light on a substrate. There is a lighting device.   The lighting device according to claim 12, wherein the band gap energy of at least a part of the semiconductor fine particles provided in the phosphor of the wavelength converter is smaller than the energy emitted by the light emitting element.   A lighting device assembly comprising a plurality of the lighting devices according to claim 12 or 13.

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