JP2016039249A - Light-emitting device and wavelength conversion element - Google Patents

Abstract

A light emitting device and a wavelength conversion element having excellent color rendering properties are provided. A light-emitting device includes a light-emitting portion that emits excitation light, a phosphor that emits fluorescence when irradiated with the excitation light, metal nanoparticles that exhibit a plasmon resonance phenomenon, and a dielectric, and a wavelength converting portion 4 having a plurality of plasmon resonance wavelengths, wherein the wavelength converting portion includes a plurality of wavelength converting particles (wavelength converting material) 10 having different plasmon resonance wavelengths, and a transparent material containing the plurality of wavelength converting particles 10. and a photosensitive resin 11 . [Selection drawing] Fig. 1

Description

  The present invention relates to a light emitting device and a wavelength conversion element.

  Generally, the performance of a lighting device (light emitting device) is determined by two factors, brightness per unit power and color rendering. The color rendering property is an index representing the property of the lighting device that affects the color appearance when an arbitrary object is illuminated. Usually, the superiority or inferiority of the color rendering properties is determined based on the sunlight spectrum. Specifically, it is determined that the lighting device is more excellent in color rendering as the color looks closer to natural light, and the lighting device is determined to be inferior in color rendering as the color appears farther from natural light. . The color rendering properties of conventional lighting devices using light emitting diodes (LEDs) are often insufficient. For example, when it is required to distinguish a slight difference in color as in a lighting device used in a museum or a medical institution, the low color rendering property of the lighting device may be a problem. Therefore, research for improving the color rendering properties of LED lighting has been actively conducted.

  The LED lighting device includes an LED chip and a wavelength conversion layer as basic components. Part of the light emitted from the LED chip is converted into light of other wavelengths by the wavelength conversion layer. In the LED lighting device, among the light emitted from the LED chip, the light that has not been wavelength-converted by the wavelength conversion layer and the light that has been wavelength-converted by the wavelength conversion layer are extracted to the outside in a mixed state. White light is obtained.

  Patent Document 1 discloses an LED including an LED chip that emits blue light and a phosphor that absorbs blue light and emits yellow light. In the LED of Patent Document 1, electric power is supplied to the LED through the inner lead, and blue light is emitted from the LED. An LED capable of emitting white light can be realized by mixing blue light from the LED and yellow light generated by the phosphor.

  Non-Patent Document 1 discloses optical characteristics of a wavelength conversion material in which gold nanorods are coated with a silicone resin containing a phosphor. According to Non-Patent Document 1, it is described that in this wavelength conversion material, the luminescence of the phosphor can be enhanced at the plasmon resonance wavelength of the gold nanorod by inducing the plasmon of the gold nanorod.

Non-Patent Document 2 describes that the plasmon resonance wavelength of metal nanoparticles varies depending on the refractive index of the material around the metal nanoparticles.
Non-Patent Document 3 describes that the plasmon resonance wavelength of a metal nanoparticle varies depending on the aspect ratio of the metal nanoparticle having a rod shape.

Japanese Patent Laid-Open No. 10-242513

Nanoscale, (UK), March 2011, p. 3849-3859 Takayuki Okamoto and Kotaro Kajikawa, “Plasmonics-Fundamentals and Applications”, Kodansha, October 1, 2010, p.74-77 J. Phys. Chem. B, (USA), April 2, 1999, 103, pp. 3073-3077.

  However, the color of the object may appear unnatural due to insufficient color rendering in the prior art lighting device. In particular, there are many inconveniences in scenes where it is necessary to distinguish small color differences, such as museums and medical sites.

  One embodiment of the present invention has been made to solve the above-described problems, and an object thereof is to provide a light-emitting device and a wavelength conversion element having excellent color rendering properties.

  A light-emitting device according to one aspect of the present invention includes a light-emitting unit that emits excitation light, a phosphor that generates fluorescence when irradiated with the excitation light, metal nanoparticles that exhibit a plasmon resonance phenomenon, and a dielectric. And a wavelength converter having a plurality of plasmon resonance wavelengths.

  In the light emitting device according to one aspect of the present invention, the dielectric may include a plurality of types of dielectrics having different refractive indexes.

  In the light emitting device according to one aspect of the present invention, the metal nanoparticles may include a plurality of types of metal nanoparticles having different aspect ratios.

  In the light emitting device according to one aspect of the present invention, the aspect ratio of the metal nanoparticles may be in the range of 1: 1 to 1: 5.

  In the light emitting device according to one aspect of the present invention, the metal nanoparticles may include a plurality of types of metal nanoparticles having different materials.

  In the light emitting device according to one aspect of the present invention, the metal nanoparticles may be formed using gold or silver.

  In the light emitting device according to one aspect of the present invention, the metal nanoparticles may be covered with the dielectric containing the phosphor.

  In the light emitting device according to one aspect of the present invention, the wavelength conversion unit has a stacked structure including a first layer made of the dielectric containing the metal nanoparticles and a second layer made of the phosphor. It is good also as composition which has.

  The light emitting device according to one aspect of the present invention may be configured such that the difference between the closest wavelengths of the plurality of plasmon resonance wavelengths is in a relationship of 20 nm to 50 nm.

  In the light emitting device according to one aspect of the present invention, an average distance between the metal nanoparticles and the phosphor may be equal to or less than an average diameter of the metal nanoparticles.

  In the light-emitting device according to one aspect of the present invention, the light emitted from the light-emitting portion may be blue light.

  The wavelength conversion element according to one aspect of the present invention includes a phosphor that generates fluorescence when irradiated with excitation light, metal nanoparticles that exhibit a plasmon resonance phenomenon, and a dielectric, and has a plurality of plasmon resonance wavelengths. It is characterized by.

  According to one aspect of the present invention, it is possible to provide a light emitting device and a wavelength conversion element having higher color rendering properties.

Sectional drawing which shows schematic structure of the illuminating device of 1st Embodiment. The schematic block diagram which shows schematic structure of wavelength conversion particle | grains. (A), (B) is a figure which shows the modification of a housing | casing. The figure which shows schematic structure of the illuminating device of 2nd Embodiment. The figure which shows schematic structure of the illuminating device of 3rd Embodiment. The figure which shows schematic structure of the illuminating device of 4th Embodiment. Sectional drawing which shows schematic structure of the illuminating device of 5th Embodiment. FIG. 6 is a diagram illustrating a schematic configuration of a lighting device according to a second embodiment. FIG. 10 is a diagram illustrating a schematic configuration of a lighting device according to a third embodiment. FIG. 10 is a diagram illustrating a schematic configuration of a lighting device according to a fourth embodiment. The figure which shows a sunlight spectrum and the emission spectrum of the conventional illuminating device.

Hereinafter, each embodiment of the lighting device according to the present invention will be described.
In the following drawings, in order to make each component easy to see, the scale of the size may be varied depending on the component.

[First Embodiment]
Hereinafter, 1st Embodiment of the illuminating device which concerns on this invention is described.
FIG. 1 is a cross-sectional view illustrating a schematic configuration of the illumination device according to the first embodiment. FIG. 2 is a schematic configuration diagram illustrating a schematic configuration of the wavelength conversion particles. 2, the symbol L ₁ is the major axis length of the metal nanoparticles 12, and the symbol L ₂ is the minor axis length of each metal nanoparticle 12.

  As shown in FIG. 1, a lighting device (light emitting device) 1 according to this embodiment includes a housing 2, a light emitting unit (light emitting element) 3, a wavelength converting unit (wavelength converting element) 4, and a conductive wire 5. .

(Casing)
The housing 2 accommodates the light emitting element (light emitting unit) 3 and the wavelength converting unit 4 therein. The housing 2 has an opening 2 </ b> A that contacts the bottom surface 4 b and the side peripheral surface 4 c of the wavelength conversion unit 4 and exposes the top surface 4 a of the wavelength conversion unit 4.

  By making the housing 2 have a shape that surrounds the periphery of the wavelength conversion unit 4, an effect of firmly fixing the wavelength conversion unit 4 can be obtained. The opening 2A of the housing 2 is for securing a light extraction path from the light emitting element 3 fixed on the bottom surface 2b.

As the housing 2, for example, a housing made of an inorganic material made of glass, quartz or the like, a plastic containing polyethylene terephthalate, polycarbazole, polyimide or the like, a housing made of an insulating material such as ceramics containing alumina, or aluminum ( A case in which a surface of an insulating material including silicon oxide (SiO ₂ ), an organic insulating material or the like is coated on a metal material including Al) or iron (Fe) or the like, and a surface of a metal substrate including Al or the like is anodized. A case or the like that has been subjected to insulation treatment by a method can be given.

The housing 2 is required to have good thermal conductivity in order to efficiently release heat generated in the light emitting element 3 and the wavelength conversion unit 4. The thermal conductivity, preferably 0.1W · ^{m -1} · ^K -1 or more, more preferably more than 1.0W · ^{m -1} · ^K -1.
In addition, the material which can be used as the housing | casing 2 is not limited to an above-described thing.

(Light emitting element)
The light emitting element 3 emits excitation light for exciting the phosphor of the wavelength conversion unit 4.
The light-emitting element 3 is an electroluminescent device that emits light when a voltage is applied and a current flows, and is required to emit light having a wavelength of 390 nm to 500 nm. Here, it is more preferable that the peak wavelength of the emission intensity spectrum of the light emitting element 3 is in the range of 430 nm to 470 nm.

  As the light-emitting element 3, any one of an LED having a main composition of In, Ga, and N, an organic Electro-Luminescence (hereinafter referred to as “OLED”) element, and a laser diode (hereinafter referred to as “LD”). However, the present invention is not limited to this.

  Moreover, the light emitting element 3 may be in a state in which not only one LED but also a plurality of LEDs are arranged.

(Conductive wire)
The conductive wire 5 is preferably made of a material having low electrical resistivity and high thermal conductivity. The electrical resistivity is 1.0 × 10 ⁻⁷ Ωm or less, more preferably 1.0 × 10 ⁻⁷ Ωm or less. The conductive wire 5 is preferably 10 W · m ⁻¹ · K ⁻¹ or more, more preferably 100 W · m ⁻¹ · K ⁻¹ or more. Specifically, it is preferably formed using a metal such as gold, silver, copper, platinum, aluminum, or an alloy thereof. The conductive wire 5 is connected to an anode and a cathode (both not shown) of the light emitting element 3, and an external voltage can be applied to the light emitting element 3.

(Wavelength converter)
As illustrated in FIG. 1, the wavelength conversion unit 4 includes a plurality of wavelength conversion particles (wavelength conversion materials) 10 having different plasmon resonance wavelengths, and a translucent resin 11 including the plurality of wavelength conversion particles 10. Each of the plurality of wavelength conversion particles 10 in the present embodiment has metal nanoparticles 12 having different plasmon resonance wavelengths.

  As an example, in the present embodiment, a configuration including at least two types of wavelength conversion particles 10a and 10n will be described, but not limited to this, three or more types of wavelength conversion particles 10 may be used.

  The translucent resin 11 confines and protects the light emitting element 3, the conductive wire 5, and the wavelength conversion particle 10, and a part or all of the light emitted from the light emitting element 3 is absorbed by the wavelength conversion particle 10. It is provided for the purpose of fixing a large number of wavelength conversion particles 10 in a dispersed state.

  As a material of the translucent resin 11, a transparent material containing an inorganic material such as a resin or glass containing an organic material that is cured by heat or light is preferable. Moreover, it is preferable to have high heat resistance so that it may not deteriorate with the heat | fever emitted from the light emitting element 3 and the some wavelength conversion particle | grains 10.

  Specifically, the heat resistant temperature is preferably 100 ° C. or higher, more preferably 150 ° C. or higher. For example, one or more types of photosensitive resins with reactive vinyl groups such as silicone resins, epoxy resins, acrylic resins, methacrylic resins, poly vinyl cinnamate resins, hard rubber resins, etc. are used. Is possible. An example of the inorganic material is quartz glass, but is not limited thereto.

  In order to create the wavelength conversion unit 4, first, a plurality of wavelength conversion particles 10 are placed and dispersed in the liquid state before the resin is cured. The dispersed liquid is poured into the housing 2 to which the light emitting element 3 and the conductive wire 5 are attached, and is cured by heat or light.

(Wavelength conversion particles)
As shown in FIG. 2, each wavelength conversion particle 10 includes metal nanoparticles 12, a plurality of fluorescent molecules (phosphors) 13, and a dielectric 14. Specifically, the wavelength conversion particle 10 is obtained by covering the surface of the metal nanoparticle 12 with a dielectric 14 of a dielectric medium containing a plurality of fluorescent molecules 13. The aspect ratios of the metal nanoparticles 12 in the plurality of wavelength conversion particles 10 are different from each other.

  As the metal nanoparticles 12, those capable of expressing a plasmon resonance phenomenon and having a resonance wavelength in a wavelength region of light emitted from the light emitting element 3 are used.

  “Plasmon resonance phenomenon” refers to a state in which electrons of fine particles such as metal nanoparticles 12 resonate with an electric field of light. The plasmon resonance phenomenon is caused when light is incident from a material with a high refractive index to a material with a low refractive index below the critical angle and totally reflected and oozes into a material with a low refractive index, or the diameter is smaller than the wavelength of light. It is also excited when electrons such as metal particles resonate with near-field light (evanescent light) in the case of light entering from the opening when light enters the opening.

  When the resonance wavelength of the metal nanoparticle 12 overlaps a part of the emission spectrum of the fluorescent molecule 13, plasmon resonance occurs between the fluorescent molecule 13 and the metal nanoparticle, and light emission at the resonance wavelength is enhanced. That is, fluorescence enhancement occurs at the plasmon resonance wavelength.

  In the present embodiment, the aspect ratios of the metal nanoparticles 12 that are the core of each particle are different among the plurality of wavelength conversion particles 10. Thereby, the plasmon resonance wavelengths between the plurality of wavelength conversion particles 10 are different, and plasmon resonance occurs at a plurality of wavelengths.

  For example, a plurality of wavelength conversion particles 10 prepared by coating the surfaces of a plurality of metal nanoparticles 12 having an aspect ratio of 1: 1 to 1: 5 with a dielectric 14 having a refractive index of 2.0 is prepared. .

  FIG. 1 illustrates a configuration including at least two types of wavelength conversion particles 10a and 10n. 2A has spherical metal nanoparticles 12a with an aspect ratio of 1: 1, and wavelength-converted particles 10n shown in FIG. 2B have an aspect ratio of 1: 5. It has rod-shaped metal nanoparticles 12n.

  The plasmon resonance wavelength gradually increases as the aspect ratio of the metal nanoparticles 12 increases. When the aspect ratio of the metal nanoparticles 12 exceeds 1: 5, the plasmon resonance wavelength exceeds 700 nm. When the plasmon resonance wavelength exceeds 700 nm, the visibility is greatly lowered, and it becomes difficult for a person to visually recognize even if the excitation light is enhanced. Therefore, in this embodiment, it is desirable that the aspect ratio of each metal nanoparticle 12 be in the range from 1: 1 to 1: 5.

Specifically, the size of the metal nanoparticles 12 are preferably long axis length _{L 2} is at 700nm or less. More preferably, it is 100 nm or less. When major axis L ₂ is at 100nm or less, easily resonance plasmon no delaying effect.

  Note that the aspect ratios of the metal nanoparticles 12 in the plurality of wavelength conversion particles 10 may be discretely different. However, since the peak wavelength of the emission spectrum after enhancement has a half width of 50 nm, it is desirable to suppress the difference between the nearest wavelengths among the plasmon resonance wavelengths in each metal nanoparticle 12 to 50 nm or less.

  Examples of the material of the metal nanoparticles 12 include Au, Ag, Al, Pt, Cu, Mn, Mg, Ca, Li, Yb, Eu, Sr, Ba, Na, etc., and two or more kinds of these metals. Examples of alloys formed by appropriately selecting the above materials include Mg: Ag, Al: Li, Al: Ca, and Mg: Li.

  The material for forming the metal nanoparticles 12 is not limited to the above, and any material that can induce the plasmon resonance phenomenon may be used.

  The dielectrics 14 respectively covering the periphery of the plurality of metal nanoparticles 12 are composed of, for example, a silica layer having a thickness of several nm.

  The plurality of fluorescent molecules 13 enclosed in the dielectric 14 needs to have an absorption spectrum overlapping with the emission spectrum of the light-emitting element 3 and an emission spectrum overlapping with the plasmon resonance wavelength. When this condition is satisfied, light emitted from the light emitting element 3 is absorbed by the fluorescent molecules 13, and plasmons are excited in the metal nanoparticles by energy transfer from the excited fluorescent molecules 13. Thereafter, light having a plasmon resonance wavelength is emitted from the metal nanoparticles 12. Thereby, even if it is the light of the wavelength of the base part of the emission spectrum from the fluorescent molecule 13, light emission can be enhanced.

  As the material of the fluorescent molecule 13, a known phosphor material can be used. Such phosphor materials are classified into organic phosphor materials and inorganic phosphor materials. Specific examples of these compounds are shown below, but the present invention is not limited to these materials.

  As an organic fluorescent material, as a fluorescent dye that converts blue excitation light into green light, coumarin dyes: 2,3,5,6-1H, 4H-tetrahydro-8-trifluoromethylquinolidine (9, 9a, 1-gh) Coumarin (coumarin 153), 3- (2'-benzothiazolyl) -7-diethylaminocoumarin (coumarin 6), 3- (2'-benzimidazolyl) -7-N, N-diethylaminocoumarin (coumarin 7) ), Naphthalimide dyes: basic yellow 51, solvent yellow 11, solvent yellow 116, and the like.

  As fluorescent dyes that convert blue excitation light into red light, cyanine dyes: 4-dicyanomethylene-2-methyl-6- (p-dimethylaminostyryl) -4H-pyran, pyridine dyes: 1-ethyl- 2- [4- (p-dimethylaminophenyl) -1,3-butadienyl] -pyridinium-perchlorate and rhodamine dyes: rhodamine B, rhodamine 6G, rhodamine 3B, rhodamine 101, rhodamine 110, basic violet 11, sulfo Rhodamine 101 etc. are mentioned.

  Further, examples of the fluorescent type that converts blue excitation light into yellow light to red light include perylene dyes: lumogen red, lumogen yellow, lumogen orange, other body pi dyes, squaraine dyes, and the like.

Inorganic phosphor materials include (BaMg) Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ , Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺ , (SrBa) Al as phosphors that convert blue excitation light into green light. ₁₂ Si ₂ O ₈ : Eu ²⁺ , (BaMg) ₂ SiO ₄ : Eu ²⁺ , Y ₂ SiO ₅ : Ce ³⁺ , Tb ³⁺ , Sr ₂ P ₂ O ₇ -Sr ₂ B ₂ O ₅ : Eu ²⁺ , (BaCaMg) ₅ (PO ₄ ) 3Cl: Eu ²⁺ , Sr ₂ Si ₃ O ₈ -2SrCl ₂ : Eu ²⁺ , Zr ₂ SiO ₄ , MgAl ₁₁ O ₁₉ : Ce ³⁺ , Tb ³⁺ , Ba ₂ SiO ₄ : Eu ²⁺ , Sr ₂ SiO ₄ : Eu ²⁺ , (BaSr) SiO ₄ : Eu ^{2+ and the} like.

As phosphors that convert blue excitation light into red light, Y ₂ O ₂ S: Eu ³⁺ , YA ₁ O ₃ : Eu ³⁺ , Ca ₂ Y ₂ (SiO ₄ ) 6: Eu ³⁺ , LiY ₉ (SiO ₄ ) ₆ O ₂ : Eu ³⁺ , YVO ₄ : Eu ³⁺ , CaS: Eu ³⁺ , Gd ₂ O ₃ : Eu ³⁺ , Gd ₂ O ₂ S: Eu ³⁺ , Y (P, V) O ₄ : Eu ³⁺ , Mg ₄ GeO _5.5 F: Mn ⁴⁺ , Mg ₄ GeO ₆ : Mn ⁴⁺ , K ₅ Eu _2.5 (WO ₄ ) _6.25 , Na ₅ Eu _2.5 (WO ₄ ) _6.25 , K ₅ Eu _2.5 (MoO ₄ ) _6.25 , Na ₅ Eu _2.5 (MoO ₄ ) _{6.25, and the} like.

  Since the above-mentioned dye is particularly easily excited by blue light of 430 nm to 500 nm, it is preferably used in combination when the light emitting element emits blue light of 430 nm to 500 nm. However, light of other wavelengths (particularly, violet light of 390 nm to 430 nm) ) Can also be used.

  In combination with a light emitting element that emits violet light of 390 nm to 430 nm, for example, a dye such as cascade blue, pacific blue, and Alexa Fluor 405 that converts violet light into blue light is also used in the preceding paragraph. Although it is preferable to use it with the shown pigment | dye, it is not restricted to this.

(Method for producing wavelength conversion particles)
The plurality of wavelength conversion particles 10 described above can be prepared by the following manufacturing method as an example. Here, the manufacturing method of the wavelength conversion particles 10a and 10n will be described as an example.
For example, in a 8 mM (M = mol / L) hexadecyltrimethylammonium bromide (CTAB) solution, a plurality of metal nanoparticles 12a, 12n having different aspect ratios, a plurality of fluorescent molecules 13, Tetraethyl orthosilicate (TEOS) is dispersed. By stirring this dispersion for several days while maintaining PH = 10 to 11, a plurality of wavelength conversion particles 10a and 10n are produced, in which the surfaces of the metal nanoparticles 12a and 12n are coated with a silicone resin containing a fluorescent dye. it can.

  Of course, it is only necessary to coat the surfaces of the metal nanoparticles 12a and 12n with the dielectrics 14 mixed with a plurality of fluorescent molecules 13, and therefore other manufacturing methods may be used.

  In order to improve the color rendering properties of the lighting device 1, it is necessary to realize a spectrum similar to the sunlight spectrum.

FIG. 11 is a diagram showing a sunlight spectrum and an emission spectrum of a conventional lighting device. The horizontal axis indicates the wavelength [nm], and the vertical axis indicates the light intensity [mW / cm ² ].
As shown in FIG. 11, the sunlight spectrum P has a flat shape over the entire visible light region as compared with the emission spectrum S of the conventional illumination device. The emission spectrum S of the conventional lighting device is biased to some colors such as blue and yellow. Therefore, in order to realize the illumination device 1 having higher color rendering properties, it is necessary to increase red light, orange light, and the like.

  When it is desired to enhance light emission at a specific wavelength, the wavelength conversion particle 10 having the metal nanoparticle 12 having the same plasmon resonance wavelength as the core as a core is prepared, and a larger number of the wavelength conversion particles 10 are put in the wavelength conversion unit 4. What should I do? That is, by adjusting the concentration of several types of wavelength conversion particles 10 having various plasmon resonance wavelengths for each plasmon resonance wavelength (for each wavelength of light to be enhanced), the emission spectrum emitted from the wavelength conversion unit 4 is obtained. It can be changed freely.

  For this reason, it is particularly preferable to increase the wavelength of the base portion of the emission spectrum on the longer wavelength side from the emission peak of the fluorescent molecule 13. More preferably, it is desirable to enhance a plurality of wavelengths in the base portion of the emission spectrum of the fluorescent molecule 13. This is because a flat emission spectrum closer to the sunlight spectrum can be obtained.

  In the illuminating device 1 of this embodiment, the wavelength conversion part 10a which has the metal nanoparticle 12a of aspect ratio 1: 1, and the wavelength conversion particle 10n which has the metal nanoparticle 12n of aspect ratio 1: 5 are wavelength conversion parts. Although it is set as the structure mixed in 4, 3 or more types of wavelength conversion particles may be mixed.

  Plural wavelength conversion particles 10 having different shapes (particularly aspect ratio) of the metal nanoparticles 12 are mixed in the wavelength conversion unit 4 so that excitation light in a wavelength range of about 520 nm to about 700 nm can be plasmon resonance. It can be strengthened with. Thereby, the emitted light intensity of green light to deep red light can be raised.

  In this way, by adjusting the aspect ratio of the metal nanoparticles 12, it becomes possible to effectively enhance the excitation light having a wavelength in a certain region. As a result, the emission spectrum of the light emitted from the wavelength converter 4 can be brought close to the sunlight spectrum. Therefore, the lighting device 1 having higher color rendering properties can be obtained.

  The enhanced emission spectrum usually has a peak with a half width of about 50 nm centered on the plasmon resonance wavelength. Therefore, it is more desirable that there are wavelengths that are separated from each other by 20 nm or more among the wavelengths of the plurality of emission spectra to be enhanced. Specifically, it is more desirable that the nearest wavelengths among the wavelengths of the plurality of emission spectra to be enhanced are in the range of 20 nm to 50 nm. If it is less than 20 nm, the peaks of the emission spectrum almost overlap each other, and the effect of broadening the emission spectrum by fluorescence enhancement using plasmon resonance is small.

  In addition, when the plasmon resonance wavelength of the metal nanoparticle 12 matches the wavelength of the excitation light (absorption wavelength of the fluorescent molecule), the excitation light is enhanced by the plasmon resonance in the vicinity of the metal nanoparticle 12. That is, an excitation light enhancing action occurs. In this case, it is considered that quenching by the metal nanoparticles 12 does not occur. As the distance from the surface of the metal nanoparticle 12 increases, the range exerted by the enhanced electric field strength decreases. For this reason, it is necessary to arrange the fluorescent molecules 13 within the range affected by the enhanced electric field strength.

  In that respect, according to the wavelength conversion particle 10 of the present embodiment, since the periphery of the metal nanoparticle 12 is covered with the dielectric 14 containing the fluorescent molecule 13, the fluorescent light is sufficiently close to the metal nanoparticle 12. Molecule 13 is present. Thereby, light emission is efficiently generated with a small amount of fluorescent molecules 13. That is, since there is no fluorescent molecule 13 that does not contribute to fluorescence enhancement, higher brightness fluorescence can be obtained.

  It is possible to examine later whether the wavelength conversion unit 4 in the illumination device 1 described above has a plurality of different plasmon resonance wavelengths.

First, the wavelength conversion unit 4 is peeled from the housing 2.
Next, a large number of wavelength conversion particles 10 constituting the wavelength conversion unit 4 and a translucent resin 11 in which the large number of wavelength conversion particles 10 are dispersed are separated. At this time, the translucent resin 11 may be dissolved by a dissolving chemical. For example, when the translucent resin 11 is made of a silicone resin, sodium hydroxide may be used, and when the translucent resin 11 is made of an acrylic resin, ethanol may be used.

  Next, each dielectric 14 in each wavelength conversion particle 10 is melted to separate the metal nanoparticles 12 and the numerous fluorescent molecules 13.

  And the material of the metal nanoparticle 12 can be known by observing the metal nanoparticle 12 with SEM or TEM, observing the shape of the metal nanoparticle 12 and analyzing the composition.

  The plasmon resonance wavelength is determined by the shape and material of the metal nanoparticles 12. Therefore, by examining the shape and material of the metal nanoparticles 12, it is possible to know which wavelength is enhanced in fluorescence.

  Further, the fluorescent molecule 13 is spectrally analyzed, and the absorption and emission spectra of the fluorescent molecule 13 are examined. Furthermore, molecular structure can be known by using NMR, Mass spectrum, FTIR, etc. together.

In addition, the shape of the housing | casing 2 is not restricted to what was mentioned above.
For example, like the case 201 shown in FIG. 3A, the entire shape may be a concave shape that is curved. That is, it is good also as a shape which covers the curved surfaces 401b other than the upper surface 401a of the wavelength conversion part 401 whose cross-sectional shape makes a hemisphere.
Further, as in the case 202 shown in FIG. 3B, a plate-like one that contacts only the bottom surface 4b of the wavelength conversion unit 4 may be used. Other changes can be made as appropriate.

[Second Embodiment]
Hereinafter, an embodiment of the illumination device according to the second embodiment will be described.
The basic configuration of the illumination device of the present embodiment is substantially the same as the configuration of the previous embodiment, but differs in the configuration of the wavelength conversion unit. Therefore, in the following description, the configuration of the wavelength conversion unit will be described in detail, and description of other common components will be omitted.

FIG. 4 is a diagram illustrating a schematic configuration of the illumination device according to the second embodiment.
As shown in FIG. 4, the illuminating device (light emitting device) 20 in this embodiment is a wavelength conversion unit (wavelength conversion unit) in which a plurality of wavelength conversion particles (wavelength conversion materials) 21 having different plasmon resonances are dispersed as a wavelength conversion material. Conversion element) 22. Specifically, the refractive index of the dielectric 14 covering the surface of the metal nanoparticle 12 is different among the plurality of wavelength conversion particles 21.

  In the present embodiment, a configuration including a wavelength conversion unit 22 in which at least two types of wavelength conversion particles 21a and 21m are dispersed will be described. However, the configuration is not limited thereto, and three or more types of wavelengths having different refractive indexes of the dielectric 14 are described. The conversion particles 21 may be dispersed.

  In the present embodiment, two types of dielectrics 14a and 14m having different refractive indexes are used. That is, there are a plurality of wavelength conversion particles 21a whose surface is coated with the metal nanoparticles 12 with the dielectric 14a and a plurality of wavelength conversion particles 21m whose surface is coated with the metal nanoparticles 12 with the dielectric 14m.

  The metal nanoparticles 12 in the wavelength conversion particles 21a and 21m are gold nanospheres having an aspect ratio of 1: 1. The metal nanoparticles 12 have a diameter of about 200 nm.

  The numerous fluorescent molecules 13 included in the dielectrics 14a and 14m are made of any of the materials described in the first embodiment.

  In this embodiment, the refractive index of the dielectric 14 used for the surface coating of the metal nanoparticles 12 is in the range of, for example, 1.35 to 1.81. The range of the refractive index of the dielectric 14 is an example and is not particularly limited.

  For example, the material of the dielectric 14 having a refractive index of 1.35 includes fluororesin. Further, for example, as a material of the dielectric 14 having a refractive index of 1.81, ultrahigh refractive index resin (Nissan Chemical UR-501) and the like can be mentioned.

  Here, in the case of the wavelength conversion particle 21a obtained by coating the surface of the metal nanoparticle 12 having an aspect ratio of 1: 1 with the dielectric 14a having a refractive index of 1.35, the plasmon resonance wavelength is 530 nm. In the case of the wavelength conversion particle 21m formed by coating with a dielectric 14m having a refractive index of 1.81, the plasmon resonance wavelength is 580 nm.

  Thus, the plasmon resonance wavelength becomes longer as the refractive index of the dielectric 14 that coats the surface of the metal nanoparticle 12 becomes higher. That is, the plasmon resonance wavelength can be varied not only by the shape of the metal nanoparticles 12 but also by the refractive index of the dielectric 14.

  As described above, in the lighting device 20 of the present embodiment, by mixing at least two types of wavelength conversion particles 21a and 21m having different refractive indexes of the dielectrics 14a and 14m covering the metal nanoparticles 12, The excitation light in the wavelength range of yellow light and red light can be enhanced by plasmon resonance.

  By using a plurality of dielectrics 14 having different refractive indexes as the dielectrics 14 covering the metal nanoparticles 12 and mixing various types of wavelength conversion particles 21, excitation light in a wide wavelength range can be converted into plasmons. It can be enhanced by resonance. Thereby, it is possible to effectively enhance excitation light having a wavelength in a certain region. Therefore, the lighting device 1 having higher color rendering properties can be obtained.

[Third Embodiment]
Hereinafter, an embodiment of the illumination device of the third embodiment will be described.
The basic configuration of the illumination device of the present embodiment is substantially the same as the configuration of the first embodiment, but differs in the configuration of the wavelength conversion unit. Therefore, in the following description, the configuration of the wavelength conversion unit will be described in detail, and description of other common components will be omitted.

FIG. 5 is a diagram illustrating a schematic configuration of the illumination device according to the third embodiment.
As shown in FIG. 5, the illuminating device (light emitting device) 30 of this embodiment has a plurality of types of wavelength converting particles (wavelength converting materials) 31 (A, B,..., T) having different plasmon resonances as wavelength converting materials. Is provided with a wavelength conversion unit (wavelength conversion element) 32 in which a large number of particles are dispersed.

Specifically, each of the plurality of wavelength conversion particles 31 has a refractive index of the surface of each of the plurality of metal nanoparticles 12 (a, b,..., N) having an aspect ratio in the range of 1: 1 to 1: 5. Each of them is covered with a plurality of different dielectrics 14 (a, b,..., M) within a range of 1.35 to 1.81.
Here, T, n, and m are natural numbers of 1 or more, respectively.

  For example, when the upper limit and lower limit of the aspect ratio of the metal nanoparticles 12 and the upper limit and lower limit of the refractive index of the dielectric 14 are combined, the following four types of wavelength conversion particles 31 are obtained. As a first type, there is a wavelength conversion particle 31A obtained by coating the surface of a metal nanoparticle 12a having an aspect ratio of 1: 1 with a dielectric 14a having a refractive index of 1.35. As the second type, there is a wavelength conversion particle 31B obtained by coating the surface of the metal nanoparticle 12b having an aspect ratio of 1: 5 with a dielectric 14a having a refractive index of 1.35. As the third type, there is a wavelength conversion particle 31S obtained by coating the surface of the metal nanoparticle 12a having an aspect ratio of 1: 1 with a dielectric 14b having a refractive index of 1.81. As a fourth type, there is a wavelength conversion particle 31T obtained by coating the surface of the metal nanoparticle 12b having an aspect ratio of 1: 5 with a dielectric 14b having a refractive index of 1.81.

  That is, it is sufficient that at least one of the aspect ratio of the metal nanoparticles 12 and the dielectric 14 is different between the plurality of wavelength conversion particles 31. Therefore, it is not limited to the above four types.

  A combination of each type of metal nanoparticles 12 and each type of dielectric 14 is appropriately selected. By combining the aspect ratio of the metal nanoparticles 12 and the refractive index of the dielectric 14, the plasmon resonance wavelength of the wavelength conversion particle 31 can be adjusted over a wider wavelength range.

[Fourth Embodiment]
Hereinafter, an embodiment of the illumination device of the fourth embodiment will be described.
The basic configuration of the illumination device of the present embodiment is substantially the same as the configuration of the first embodiment, but differs in the configuration of the wavelength conversion unit. Therefore, in the following description, the configuration of the wavelength conversion unit will be described in detail, and description of other common components will be omitted.

FIG. 6 is a diagram illustrating a schematic configuration of the illumination device according to the fourth embodiment.
As shown in FIG. 6, the illumination device (light emitting device) 40 of the present embodiment includes two types of first wavelength conversion particles (wavelength conversion material) 41 and second wavelength conversion particles (wavelength conversion material) having different plasmon resonance. A wavelength conversion unit (wavelength conversion element) 43 in which a plurality of 42 are mixed is provided. Specifically, the first wavelength conversion particle 41 and the second wavelength conversion particle 42 are different in the material of the metal nanoparticles 12 serving as the core.

The first wavelength conversion particle 41 is configured by coating the surface of a metal nanoparticle 12a made of Au with a dielectric 14 having a predetermined refractive index with a core thereof.
The second wavelength conversion particle 42 is configured by coating the surface of the metal nanoparticle 12b made of Ag with the dielectric 14 with the core 12b.

  The gold nanoparticles 12a and the silver nanoparticles 12b have an aspect ratio in the range of 1: 1 to 1: 5, respectively, and are constant with each other.

  For example, when the gold nanoparticle 12a is the first wavelength conversion particle 41 whose surface is coated with the dielectric material 14 having a refractive index of 2.0, for example, the excitation light in the wavelength region of about 520 nm to about 700 nm is enhanced by plasmon resonance. Can do.

  On the other hand, in the case of the second wavelength conversion particle 42 using the silver nanoparticles 12b, the plasmon resonance wavelength is shortened to about 400 nm. Further, by changing the aspect ratio of the silver nanoparticles 12b, the plasmon resonance wavelength can be gradually increased from 400 nm.

  In this manner, by mixing a plurality of metal nanoparticles 12a and 12b made of different materials in the wavelength conversion unit 43, light of different wavelengths can be enhanced by plasmon resonance.

[Fifth Embodiment]
Hereinafter, an embodiment of the illumination device of the fifth embodiment will be described.
FIG. 7 is a cross-sectional view illustrating a schematic configuration of the illumination device according to the fifth embodiment.

  As illustrated in FIG. 7, the illumination device (light emitting device) 50 according to the fifth embodiment includes a first substrate 52, a light emitting unit 53, a second substrate 54, and a dielectric layer (including a plurality of metal nanoparticles 12). A first layer) 56, a color conversion unit (second layer) 57 including a phosphor, and a third substrate 58. On the first surface 52a of the first substrate 52, the light emitting unit 53 and the second substrate 54 are stacked in this order from the first substrate 52 side. On the second surface 52b of the first substrate 52, a dielectric layer 56, a color converter (wavelength converter) 57, and a third substrate 58 are stacked in this order from the first substrate 52 side. The light emitting unit 53 is composed of an organic EL element formed on the first substrate 52. The dielectric layer 56 and the color conversion unit 57 are formed on the second surface 52 b of the first substrate 52.

  The light emitting unit 53 emits excitation light for exciting the phosphor of the color conversion unit 57. The color conversion unit 57 is provided on the light emission side (upper layer side in FIG. 7) of the light emitting unit 53. The color conversion unit 57 includes a phosphor that generates fluorescence when irradiated with excitation light. In the color conversion unit 57, the phosphor absorbs excitation light and emits fluorescence having a color different from that of the excitation light. As a result, the color of the excitation light emitted from the light emitting unit 53 is converted. The dielectric layer 56 is provided between the light emitting unit 53 and the color conversion unit 57. The dielectric layer 56 is composed of a dielectric medium 9 containing two types of metal nanoparticles 12R and 12G that express different plasmon phenomena.

As the first substrate 52, for example, an inorganic material substrate made of glass, quartz or the like, a plastic substrate including polyethylene terephthalate, polycarbazole, polyimide, or the like, an insulating substrate such as a ceramic substrate including alumina, or the like, or aluminum (Al) A metal substrate containing iron (Fe) or the like, or a substrate coated with an insulator containing silicon oxide (SiO ₂ ) or an organic insulating material on the substrate, or a metal substrate containing Al or the like is anodized on the surface. And a substrate subjected to insulation treatment by the above method. However, the substrates that can be used in this embodiment are not limited to these substrates.

  The light emitting unit 53 includes a cathode 111, an anode 112, and an organic light emitting layer 130 sandwiched between the cathode 111 and the anode 112. The organic light emitting layer 130 has a configuration in which, for example, an electron injection layer 114, an electron transport layer 115, a hole prevention layer 116, a light emitter layer 117, a hole transport layer 118, and a hole injection layer 119 are stacked in this order from the cathode 111 side. Have The light emitter layer 117 emits blue light.

  The light emitting unit 53 may have a structure that exhibits a microcavity effect. As a structure that exhibits the microcavity effect, for example, it is desirable to set the thickness of the organic light emitting layer 130 so as to match the wavelength of light to be enhanced. In the organic EL element, an organic light emitting layer 130 is sandwiched between a pair of electrodes 111 and 112.

  The organic light emitting layer 130 is not limited to the configuration of the present embodiment, and may have a single layer structure of the light emitter layer 117 or a multilayer structure including the light emitter layer 117, the hole transport layer 118, the electron transport layer 115, and the like. .

  The sealing layer 121 seals the side surface of the light emitting unit 53. The sealing layer 121 can be formed using any insulating material. The insulating material may be either an organic material or an inorganic material.

  The dielectric layer 56 is formed on the second surface 52 b of the first substrate 52. The dielectric layer 56 is composed of a dielectric medium 9 including a plurality of metal nanoparticles 12R and 12G having different aspect ratios. The metal nanoparticles 12R and 12G are disposed in regions corresponding to a red pixel region PR and a green pixel region PG, which will be described later, and are not disposed in a region corresponding to the blue pixel region PB.

  The plurality of metal nanoparticles 12 </ b> R arranged in the region corresponding to the red pixel region PR have aspect ratios at which a plurality of plasmon resonance wavelengths corresponding to the wavelength in the red light region can be obtained. The plurality of metal nanoparticles 12G arranged in the region corresponding to the green pixel region PG has an aspect ratio that can obtain a plurality of plasmon resonance wavelengths corresponding to the wavelength in the green light region. Thereby, the wavelengths of the red light region and the green light region can be enhanced over a wide range.

  The dielectric medium 9 is preferably one having high transparency in the visible range. For example, polystyrene, polyvinyl alcohol (PVA), 4,4 ′-[p-sulfonylbis (phenylenesulfanyl)] diphthalic anhydride (DPSDA), Polymethyl methacrylate (PMMA), epoxy resin, or the like is used. The relative dielectric constant ε of the dielectric medium 9 is ε = 2.20 to 2.40, ε = 2.56, ε = 3.24, ε = 3.50 to 4.50, and ε = 2.50. About 6.00. The dielectric medium 9 may be other than the above.

  Here, since it is necessary for each color conversion layer to efficiently absorb the enhanced electric field in the vicinity of the excited metal nanoparticles 12R and 12G, the thickness of the dielectric layer 56 and the average diameter of the metal nanoparticles 12R and 12G are almost equal. equal.

  In the present embodiment, the average distance from the surface of the color converter 57 on the side in contact with the dielectric layer 56 to the metal nanoparticles 12R and 12G existing in the dielectric layer 56 is equal to or less than the average diameter of the metal nanoparticles 12R and 12G. It is. That is, the dielectric layer 56 is formed so that the film thickness is thinner than the thickness obtained by uniformly laminating two metal nanoparticles 12R and 12G. In other words, the dielectric layer 56 is formed to a thickness that does not allow the metal nanoparticles 12R and 12G to overlap in two steps.

  The color conversion unit 57 includes two phosphor layers, a red phosphor layer (phosphor) 123 and a green phosphor layer (phosphor) 124, and one transmission layer 125. The red phosphor layer 123 is disposed in a region corresponding to the red pixel region PR. The green phosphor layer 124 is disposed in a region corresponding to the green pixel region PG. The transmissive layer 125 is disposed in a region corresponding to the blue pixel region PB. The transmissive layer 125 has a function of transmitting blue light and adjusting a light distribution state. In the illumination device 50 of this embodiment, the blue light emitted from the light emitting unit 53 enters the color conversion unit 57. Blue light incident on the red phosphor layer 123 is converted into red light and emitted. Blue light incident on the green phosphor layer 124 is converted into green light and emitted. The blue light incident on the transmissive layer 125 has its light distribution adjusted and is emitted as blue light.

  The red phosphor layer 123 and the green phosphor layer 124 may be composed of only the phosphor materials exemplified below, and may optionally contain additives and the like, and these materials are polymer materials (conjugates). Wear resin) or a structure dispersed in an inorganic material. A black matrix 126 is formed between two adjacent phosphor layers and between the phosphor layer and the transmission layer.

In the illumination device 50 according to the present embodiment, a plurality of types of metal nanoparticles 12R having different aspect ratios are arranged in the red pixel region PR according to the wavelength of the red light region, and the green light region is disposed in the green pixel region PG. A plurality of types of metal nanoparticles 12G having different aspect ratios according to the wavelength of were arranged.
Thereby, it is possible to efficiently enhance fluorescence in a wide wavelength range of light of each color, and high-intensity fluorescence is obtained for each color.

  In the present embodiment, a plurality of types of metal nanoparticles 12R and 12G having different aspect ratios are arranged for each of the red pixel region PR and the green pixel region PG. However, the present invention is not limited to this. For example, a plurality of metal nanoparticles 12R having an aspect ratio that provides the same plasmon resonance as the wavelength of a predetermined red light region are arranged in the red pixel region PR, and the wavelength of the predetermined green light region is set in the green pixel region PG. It is good also as a structure which arrange | positions multiple metal nanoparticles 12G which have the aspect-ratio which can obtain the same plasmon resonance.

  In the present embodiment, the metal nanoparticles 12R and 12G made of gold nanoparticles are used as the core particles. However, the present invention is not limited to this. For example, the metal nanoparticles may be made of different materials. As materials for the metal nanoparticles 12R and 12G, materials that can obtain the same plasmon resonance wavelength as that of the red light region or the green light region are selected. When the materials of the metal nanoparticles 12R and 12G are different, the aspect ratios may be the same or different.

  A color filter may be provided on the light emission side of the color conversion unit 57. For example, a color filter (not shown) that cuts light longer than the blue-green wavelength region and transmits light in the blue wavelength region is provided on the upper side of the transmission layer 125 corresponding to the blue pixel region PB. A color filter having a metal hole array structure can be used. However, the present invention is not limited to this, and a color filter formed of a dielectric multilayer film may be used.

Further, for example, the dielectric layer 56 may have a configuration in which a large number of metal nanoparticles 12 whose surface is coated with a dielectric having a predetermined refractive index are dispersed in a light-transmitting resin.
Alternatively, the dielectric layer 56 may be configured by laminating a plurality of dielectric layers having different refractive indexes. It is assumed that each of the laminated dielectric layers includes a plurality of metal nanoparticles 12.

  As described above, the plasmon resonance spectrum of the wavelength conversion particle depends on the type of metal constituting the metal nanoparticle 12, the size, shape (aspect ratio), and the surrounding refractive index, as described in the above embodiments. doing. That is, depending on how to select the type of metal constituting the metal nanoparticles 12 dispersed in the wavelength conversion section, the size and shape (mainly aspect ratio) of the metal, and the refractive index of the dielectric 14 to be coated. Any wavelength in the visible light region can be enhanced by plasmons.

  If only one type of each of the metal nanoparticles 12 and the dielectric 14 as the surface coating material is used, fluorescence enhancement by plasmon resonance can be obtained only at a specific wavelength.

According to the illumination device of each embodiment described above, it is possible to obtain fluorescence enhancement by plasmon resonance at a plurality of wavelengths by using a plurality of types of wavelength conversion particles having different plasmon resonance wavelengths. Thereby, the emission spectrum of the illuminating device can be broadened and can be brought close to the emission spectrum of sunlight. As a result, it is possible to realize more ideal white light with excellent color rendering.
Therefore, the color of the object does not appear to be unnatural, and in particular, it is possible to eliminate the trouble in a scene where it is necessary to distinguish a fine color difference such as an art museum or a medical site.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, not only one type of fluorescent molecule 13 but also a plurality of types of fluorescent molecules 13 may be used.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

The lighting device of Example 1 will be described.
As the basic configuration of the illumination device according to the present example, the configuration of the illumination device in the first embodiment shown in FIGS. 1 and 2 is adopted, and at least two types of wavelength conversion particles having different aspect ratios of the metal nanoparticles 12 are used. A plurality of 10a and 10n were used. The present embodiment will be described with reference to FIGS.

  In the illuminating device 1 of Example 1, as the light emitting element 3, an LED having an emission peak of an InGaN semiconductor having an emission peak of 450 nm and a half width of about 30 nm was used. The light emitting element 3 was fixed to the bottom surface 2 b of the housing 2, and both electrodes of the light emitting element 3 were connected by conductive wires 5 and 5 so that a voltage could be applied to the light emitting element 3 from the outside of the housing 2.

  The wavelength conversion particles 10a and 10n have metal nanoparticles 12a and 12n having different shapes, respectively. In this example, gold nanospheres having an aspect ratio of 1: 1 were used as the metal nanoparticles 12a, and gold nanorods having an aspect ratio of 1: 5 were used as the metal nanoparticles 12n.

  The lighting device 1 is created as follows. Here, the creation method of the wavelength conversion unit 4 will be mainly described.

  First, in a 8 mM (M = mol / L) CTAB (cetyltrimethylammonium bromide) solution, a plurality of metal nanoparticles 12 having an aspect ratio of 1: 1 to 1: 5, and TEOS (Tetraethyl orthosilicate) are prepared. : Tetraethyl orthosilicate) and a fluorescent molecule 13 composed of a plurality of coumarins 6 (pigments) are dispersed.

  Next, the dispersion is stirred for several days while maintaining pH = 10-11. In this way, a large number of metal nanoparticles 12 coated with a silicone resin containing coumarin 6, that is, wavelength conversion particles 10 are prepared.

Next, the produced many wavelength conversion particles 10a and 10n are mixed in the translucent resin 11 made of an epoxy resin and sufficiently stirred. Thereafter, a translucent resin 11 containing a large number of wavelength converting particles 10a and 10n was placed in the housing 2 to which the light emitting element 3 is fixed, and was cured by heating at 150 ° C. for about 5 hours.
Thereby, the wavelength conversion part 4 containing many wavelength conversion particle | grains 10a and 10n is created, and the illuminating device 1 of a present Example is completed.

The characteristics of the lighting device 1 according to this embodiment will be described.
Here, the lighting apparatus 1 in the present embodiment is evaluated using the Ra value indicating the color rendering properties of light.
The Ra value (average color rendering index) is an index of how much the color of an object is reproduced compared to the reference light (that is, sunlight) when the object is illuminated with a target reference light source.

  As the reference light source, light for color measurement (illuminant) determined by the International Commission on Illumination (CIE) is used. This light corresponds to natural daylight with a color temperature of 6500K and natural diffused daylight (also called north sky daylight) entering from a north-facing window.

Here, a method for calculating the Ra value will be described.
First, the color difference ΔEi when eight kinds of predetermined test colors are illuminated with the reference light source and the sample light source is calculated.

Next, the special color rendering index Ri is measured and calculated by the following equation (1).
Ri = 100-4.6 × ΔEi (1)

Finally, the average color rendering index is an average of R1 to R8 and is calculated by the following equation (2).
Ra = ΣRi (i = 1 to 8) × 1/8 (2)

  When the same color reproduction as that of the reference light source can be performed, the Ra value is 100, and the closer the Ra value is to 100, the higher the color rendering.

  In a conventional lighting device that does not use the metal nanoparticles 12, the Ra value indicating the color rendering properties was 46. On the other hand, Ra value rose to 63 in the illuminating device 1 of a present Example.

  According to the illumination device 1 of the present embodiment, by using two types of wavelength conversion particles 10a and 10n having different aspect ratios of the metal nanoparticles 12, fluorescence of different wavelengths can be enhanced by plasmon resonance. By adopting such fluorescence enhancement by plasmon resonance, high color rendering properties could be obtained.

Next, the illuminating device of Example 2 is demonstrated.
FIG. 8 is a diagram illustrating a schematic configuration of the illumination device 20 according to the second embodiment.

  With respect to the basic configuration of the illumination device according to this example, the configuration of the illumination device in the second embodiment shown in FIG. 4 is adopted, and at least two types of wavelength conversion particles 21b having different refractive indexes of the dielectrics 14b and 14m A wavelength conversion unit 22 in which a large number of 21 m are dispersed is provided.

  That is, the wavelength conversion unit 22 in this embodiment includes a large number of wavelength conversion particles 21b and 21m in which the surface of each metal nanoparticle 12 is coated with two types of dielectrics 14b and 14m having different refractive indexes.

  In the lighting device 20 of Example 2, a silicone resin having a refractive index of 1.41 was used as the dielectric 14b, and a triazine-based polymer having a refractive index of 1.81 was used as the dielectric 14m. As the metal nanoparticles 12, gold nanospheres having an aspect ratio of 1: 1 were used.

  The illumination device 20 is created as follows. Here, the creation method of the wavelength conversion unit 22 will be mainly described.

  First, in an 8 mM (M = mol / L) CTAB (cetyltrimethylammonium bromide) solution, a plurality of metal nanoparticles 12 composed of gold nanospheres having an aspect ratio of 1: 1, TEOS (Tetrahethyl orthosilicate), and coumarin 6 ( The dye is dispersed and stirred for several days while maintaining the pH = 10-11.

  In this manner, the surface of the metal nanoparticle 12 was coated with the dielectric 14b made of silicone resin having a refractive index of 1.41 and containing coumarin 6 to prepare the wavelength conversion particle 21b.

  In addition to the wavelength conversion particle 21b, the surface of the metal nanoparticle 12 was coated using a dielectric 14m made of a triazine-based polymer having a refractive index of 1.81 instead of TEOS, thereby creating the wavelength conversion particle 21m.

  A large number of the wavelength conversion particles 21b and the wavelength conversion particles 21m are put in the translucent resin 11 made of an epoxy resin and sufficiently stirred. Thereafter, the translucent resin 11 containing a large number of the wavelength conversion particles 21b and the wavelength conversion particles 21m is placed in the housing 2 in which the light emitting element 3 is fixed, and is cured by heating at 150 ° C. for about 5 hours. .

  Thereby, the wavelength conversion part 4 containing many wavelength conversion particle | grains 21b and wavelength conversion particle | grains 21m is created, and the illuminating device 20 of a present Example is completed.

  In the illumination device 20 in the present embodiment, at least two types of wavelength conversion particles 21b and 21m having different refractive indexes of the dielectrics 14b and 14m coating the surface of the metal nanoparticles 12 are used.

  These wavelength conversion particles 21b and 21m can enhance fluorescence of two different wavelengths by plasmon resonance. By using such fluorescence enhancement by plasmon resonance, the Ra value indicating the color rendering property is 52 in the lighting device 20 in the present embodiment, and the lighting device 20 having high color rendering property can be obtained.

Next, the illuminating device of Example 3 is demonstrated.
FIG. 9 is a diagram illustrating a schematic configuration of the illumination device 60 according to the third embodiment.

  The illuminating device 60 of the present embodiment includes a wavelength conversion unit 62 in which a plurality of types of wavelength conversion particles 61b and 61m having different plasmon resonances are dispersed.

  The plurality of wavelength conversion particles 61b are made of a plurality of first metal nanoparticles 12 (a1, b1,... Different from each other in an aspect ratio of 1: 1 or more and 1: 1.25 or less by a dielectric 14b having a predetermined refractive index. ..., each surface of n1) is coated.

  The plurality of wavelength conversion particles 61m are formed on the surfaces of the plurality of second metal nanoparticles 12 (a2, b2,..., N2) different from the metal nanoparticles 12 by the dielectric 14m having a refractive index different from that of the dielectric 14b. Are coated respectively. The plurality of second metal nanoparticles 12 (a2, b2,..., N2) have different aspect ratios between 1: 1 and 1: 1.25.

  The lighting device 60 is created as follows. Here, the creation method of the wavelength converter 62 will be mainly described.

  First, a plurality of first metal nanoparticles 12 composed of different gold nanorods having an aspect ratio of 1: 1 to 1: 1.25 in an 8 mM (M = mol / L) CTAB (cetyltrimethylammonium bromide) solution. (A1, b1,..., N1), TEOS (Tetraethyl orthosilicate), and a plurality of fluorescent molecules 13 made of coumarin 6 are dispersed and stirred for several days while maintaining pH = 10-11.

  Thus, each surface of the plurality of first metal nanoparticles 12 (a1, b1,..., N1) having different aspect ratios by the dielectric 14b made of silicone resin having a refractive index of 1.41 and containing coumarin 6. A plurality of wavelength conversion particles 61b were prepared.

  In addition to the wavelength conversion particles 61b, a plurality of second metal nanoparticles 12 (a2, b2) having different aspect ratios are used by using a dielectric 14m made of a triazine-based polymer having a refractive index of 1.81 instead of TEOS. ,..., N2) were coated to produce a plurality of wavelength converting particles 61m.

  The aspect ratios of the first metal nanoparticles 12 (a1, b1,..., N1) in the plurality of wavelength conversion particles 61b are different from each other, and the plasmon resonance wavelengths of the wavelength conversion particles 61b are different from each other.

  Further, the aspect ratios of the second metal nanoparticles 12 (a2, b2,..., N2) in the plurality of wavelength conversion particles 61m are also different from each other, and the plasmon resonance wavelengths of the wavelength conversion particles 61m are also different from each other.

  A large number of the wavelength conversion particles 61b and the wavelength conversion particles 61m are put in the translucent resin 11 made of an epoxy resin and sufficiently stirred. Thereafter, the translucent resin 11 containing a large number of the wavelength conversion particles 61b and the wavelength conversion particles 61m is placed in the housing 2 in which the light emitting element 3 is fixed, and is cured by heating at 150 ° C. for about 5 hours. It was.

  In this manner, the wavelength conversion unit 32 including a large number of the plurality of types of wavelength conversion particles 61b and 61m is created in the housing 2, and the illumination device 60 of the present embodiment is completed.

  In the illumination device 60 according to the present embodiment, each surface of the plurality of metal nanoparticles 12 (a, b,..., N) having different aspect ratios is coated with one of two types of dielectrics 14b and 14m having different refractive indexes. A large number of the two series of wavelength converting particles 61b and 61m are used.

  With such a plurality of types of wavelength conversion particles 61b and 61m, it becomes possible to enhance fluorescence of a plurality of different wavelengths by plasmon resonance. Since the wavelength range of light that can be enhanced is larger than when using one type of each of the metal nanoparticles 12 and the dielectrics 14, the illumination device 30 in this embodiment has a Ra value of 77 indicating color rendering, and higher color rendering. It became the illuminating device 30 which has.

  In this embodiment, two types of dielectrics 14b and 14m are used, but three or more types of dielectrics 14 may be used. Thus, the wavelength range of light that can be enhanced can be further expanded by the combination of the aspect ratio of the metal nanoparticles 12 and the refractive index of the dielectric 14.

Next, the illuminating device of Example 4 is demonstrated.
FIG. 10 is a diagram illustrating a schematic configuration of the illumination device 70 according to the fourth embodiment.

  As shown in FIG. 10, the illumination device (light emitting device) 70 in this embodiment has a wavelength conversion unit (wavelength conversion element) 74 formed by dispersing a large number of at least two types of wavelength conversion particles (wavelength conversion materials) 71b and 71m. It has.

  The wavelength conversion particle 71b is formed by coating the surface of the metal nanoparticle 12 with a dielectric 14b including two types of fluorescent molecules 13a and 13b. The wavelength conversion particle 71m is formed by coating the surface of the metal nanoparticle 12 with a dielectric 14m including two types of fluorescent molecules 13a and 13b. The dielectric 14b and the dielectric 14m have different refractive indexes.

  In this example, in addition to the fluorescent molecule 13a made of coumarin 6, a fluorescent molecule 13b made of perylene-based lumogen red that converts blue excitation light into yellow light to red light was further used.

  The lighting device 70 is created as follows. Here, the creation method of the wavelength conversion unit 74 will be mainly described.

  First, in a 8 mM (M = mol / L) CTAB (cetyltrimethylammonium bromide) solution, a plurality of metal nanoparticles 12 made of gold nanospheres having an aspect ratio of 1: 1, TEOS (Tetraethyl orthosilicate), and coumarin 6 are used. A plurality of fluorescent molecules 13a and a plurality of fluorescent molecules 13b made of lumogen red are dispersed and stirred for several days while maintaining pH = 10-11.

  In this way, the surface of the plurality of metal nanoparticles 12 is coated with the dielectric 14b made of silicone resin having a refractive index of 1.41 in which coumarin 6 and rumogen red are mixed, and two types of fluorescent molecules 13a and 13b are coated. A plurality of wavelength conversion particles 71b including them were prepared.

  In addition to the wavelength conversion particles 71b, instead of TEOS, the dielectric 14m made of a triazine-based polymer having a refractive index of 1.81 is used to coat the surfaces of the plurality of metal nanoparticles 12, and the wavelength conversion particles 71m. Created multiple. Coumarin 6 and Lumogen Red are also mixed in the dielectric 14m. Thereby, a plurality of wavelength conversion particles 71m including two types of fluorescent molecules 13a and 13b were prepared.

  A large number of the wavelength conversion particles 71b and the wavelength conversion particles 71m are put in the translucent resin 11 made of an epoxy resin and sufficiently stirred. Thereafter, the translucent resin 11 containing a large number of wavelength conversion particles 71b and wavelength conversion particles 71m is placed in the housing 2 in which the light emitting element 3 is fixed, and is cured by heating at 150 ° C. for about 5 hours. It was.

  In the illumination device 70 according to the present embodiment, each of the dielectrics 14b and 14m having different refractive indexes includes two types of fluorescent molecules 13a and 13b. By using the wavelength conversion particles 71b and 71m obtained by coating the surface of the metal nanoparticle 12 with the dielectric 14b or the dielectric 14m, it was possible to enhance fluorescence of a wider wavelength by plasmon resonance.

  In the above embodiment, the case where the light emitting element 3 is an organic EL light emitting layer has been described. However, the present invention is not limited to this. For example, a light emitting diode (LED) such as a blue light emitting diode may be employed as the light emitting unit. In addition, when an LED is employed, blocking and transmission of light emitted by the liquid crystal may be controlled.

1, 20, 30, 40, 50, 70 ... Illumination device (light emitting device), 3, 53 ... Light emitting element (light emitting unit), 4, 22, 32, 43, 74, 401 ... Wavelength converting unit, 10, 21, 31, 71 ... wavelength conversion particles, 41 ... first wavelength conversion particles, 42 ... second wavelength conversion particles, 12, 12a, 12b, 12n, 12G, 12R ... metal nanoparticles, 13, 13a, 13b ... fluorescent molecules (fluorescence) Body), 14, 14a, 14b, 14m ... dielectric, 53 ... light emitting part, 56 ... dielectric layer (first layer), 57 ... color conversion part (second layer: wavelength conversion part), 123 ... red Phosphor layer (phosphor), 124... Green phosphor layer (phosphor)

Claims (12)

A light emitting unit for emitting excitation light;
A wavelength conversion unit including a phosphor that generates fluorescence when irradiated with the excitation light, a metal nanoparticle that exhibits a plasmon resonance phenomenon, and a dielectric, and having a plurality of plasmon resonance wavelengths. Light emitting device.   The light emitting device according to claim 1, wherein the dielectric includes a plurality of types of dielectrics having different refractive indexes.   The light emitting device according to claim 1, wherein the metal nanoparticles include a plurality of types of metal nanoparticles having different aspect ratios.   The light-emitting device according to claim 3, wherein the aspect ratio of the metal nanoparticles is within a range of 1: 1 to 1: 5.   The light emitting device according to any one of claims 1 to 4, wherein the metal nanoparticles include a plurality of types of metal nanoparticles made of different materials.   The light emitting device according to claim 1, wherein the metal nanoparticles are formed using gold or silver.   The light emitting device according to any one of claims 1 to 6, wherein the metal nanoparticles are covered with the dielectric containing the phosphor.   The wavelength conversion unit has a stacked structure of a first layer made of the dielectric containing the metal nanoparticles and a second layer made of the phosphor. The light emitting device according to item.   9. The light emitting device according to claim 1, wherein a difference between nearest wavelengths among the plurality of plasmon resonance wavelengths is in a relationship of 20 nm or more and 50 nm or less.   The light emitting device according to claim 1, wherein an average distance between the metal nanoparticles and the phosphor is equal to or less than an average diameter of the metal nanoparticles.   The light-emitting device according to claim 1, wherein the light emitted from the light-emitting unit is blue light.   A wavelength conversion element comprising a phosphor that generates fluorescence when irradiated with excitation light, a metal nanoparticle that exhibits a plasmon resonance phenomenon, and a dielectric, and having a plurality of plasmon resonance wavelengths.

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