JP2007221044A - Light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting device that efficiently emits excitation light in front of the light emitting device and realizes excellent light emission efficiency.
SOLUTION: A substrate 1, a light emitting element 2 that emits excitation light mounted on the substrate 1, and a light emitting element 2 provided around the light emitting element 2 so as to surround the light emitting element 2 are arranged in a desired direction. A side reflecting member 3 having a reflecting inner wall surface, a translucent member 5b provided on the light emitting element 2 so as to cover the light emitting element 2, and a first formed on the inner wall surface of the side reflecting member 3. The light-emitting device includes the wavelength conversion layer 4, and the second wavelength conversion layer 5 is formed by dispersing the second wavelength conversion material 5 a in the translucent member 5 b.
[Selection] Figure 1

Description

  The present invention relates to a light emitting device that converts the wavelength of light emitted from a light emitting element and extracts the light to the outside.

Conventionally, as a light emitting device that emits white light, a light emitting device having a structure in which a wavelength conversion layer including a phosphor that can convert blue light into yellow light is provided on the surface of a light emitting element (LED chip) that emits blue light. Proposed. For example, Patent Document 1 discloses a wavelength conversion layer containing a YAG phosphor expressed by a composition formula of (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ on a blue LED chip using an nGaN-based material. In the formed light emitting device, blue light is emitted from the LED chip, and a part of the blue light is changed to yellow light in the wavelength conversion layer. Therefore, a light emitting device in which blue and yellow light are mixed to present white is proposed. (See Patent Document 1).

  An example of such a light emitting device is shown in FIG. According to this figure, the light-emitting device includes a substrate 102 on which an electrode 101 is formed, a light-emitting element 103 including a semiconductor material that emits light having a central wavelength of 470 nm on the substrate 102, and a light-emitting element 103 on the substrate 102. And a wavelength conversion layer 104 provided so as to cover the wavelength conversion layer 104. The wavelength conversion layer 104 contains a wavelength conversion material 105 made of a phosphor. In addition, it is also known that a side reflection member 106 that reflects light is provided on the side surfaces of the light emitting element 103 and the wavelength conversion layer 104, if desired, and the light escaping to the side surface is focused forward to increase the intensity of the output light. Yes.

In this light emitting device, when the wavelength conversion layer 104 is irradiated with light emitted from the light emitting element 103, the wavelength conversion material 105 is excited to emit visible light, and this visible light is used as an output.
At that time, an attempt has been made to emit white light by a combination of an LED chip that emits purple light around 400 nm and a wavelength conversion layer containing a phosphor that converts red, green, and blue wavelengths (Patent Document 2). reference). For example, as described in Patent Document 2, by providing a wavelength conversion layer in which three kinds of fluorescent materials are mixed in a polymer resin so as to cover a purple LED chip, purple light is transmitted through the wavelength conversion layer. At this time, it is possible to cover the emission wavelength in a wide range by converting into red, green, and blue wavelengths, and the color rendering properties can be greatly improved.

JP 11-261114 A JP 2002-314142 A

In the above conventional light emitting device, after the excitation light emitted from the light emitting element is absorbed by the wavelength conversion material made of the phosphor in the wavelength conversion layer, it is changed to fluorescence having another wavelength and emitted in all directions. The Some of this fluorescence is emitted upward from the wavelength conversion layer and becomes the output light of the light emitting device, but light scattering occurs in the wavelength conversion material, and the other part is emitted downward from the wavelength conversion layer. Is done. As a result, light is emitted to the light emitting element side and absorbed. In addition, the light path length until the light scattered by the wavelength conversion material is emitted from the light emitting element to the outside of the wavelength conversion layer is increased, and the light is absorbed much when traveling through the light path. As a result, there has been a problem that the light emission efficiency of the light emitting device is not improved.
Therefore, an object of the present invention is to provide a light emitting device that efficiently emits excitation light in front of the light emitting device and realizes excellent light emission efficiency.

In order to solve the above problems, a light emitting device of the present invention has the following configuration.
(1) A substrate, a light emitting element that emits excitation light mounted on the substrate, and an inner wall surface that surrounds the light emitting element and surrounds the light emitting element and reflects the excitation light in a desired direction. Side reflection member, a first wavelength conversion layer formed on the inner wall surface of the side reflection member, and a second wavelength conversion formed in a path until light emitted from the light emitting element is emitted from the light emitting device. And a light-emitting device.
(2) The first wavelength conversion layer is formed by including a first wavelength conversion material having an average particle diameter of 0.1 to 50 μm in a translucent member. The light-emitting device of description.
(3) The second wavelength conversion layer is formed by containing a second wavelength conversion material, which is a compound semiconductor having an average particle size of 10 nm or less, in a light-transmitting member (1) or The light emitting device according to (2).
(4) The light emitting device according to any one of (1) to (3), wherein the first wavelength conversion layer has a thickness of 0.05 to 0.5 mm.
(5) The light emitting device according to any one of (1) to (4), wherein the thickness of the second wavelength conversion layer is 0.1 to 10 mm.
(6) The light-emitting device according to (3), wherein a band gap energy of the compound semiconductor material is in a range of 1.5 to 2.5 eV.
(7) The compound semiconductor composition has a periodic table group Ib, group II (excluding Be, Cd, Hg, Ra), group III (excluding Tl, Ac series elements), A semiconductor composed of at least two elements belonging to Group IV (excluding Pb and Hf), Group V (excluding As and Pa series), and Group VI (excluding Se and U) The light-emitting device according to (3) or (6), which is a composition.
(8) The light emitting device according to (2), wherein the first wavelength converting substance is an oxide fluorescent substance.
(9) The first output light converted by the first wavelength conversion layer and the second output light converted by the second wavelength conversion layer are mixed, and the spectrum has white light of 400 to 900 nm. The light-emitting device according to any one of (1) to (8), wherein
(10) The light emitting device according to any one of (1) to (9), wherein a peak wavelength of output light from the first wavelength conversion layer is 400 to 700 nm.
(11) The light emitting device according to any one of (1) to (10), wherein a peak wavelength of output light from the second wavelength conversion layer is 500 to 900 nm.
(12) The light-emitting device according to any one of (1) to (13), wherein a center wavelength of excitation light emitted from the light-emitting element is 450 nm or less.
(13) (1) to (12) characterized in that an opposing reflecting member is provided which covers a part of the second wavelength conversion layer and has a light reflecting surface facing the excitation light emitting surface of the light emitting element. ).
(14) The light-emitting device according to any one of (1) to (13), wherein an inner peripheral reflection member is provided so as to surround the light-emitting element inward of the side surface reflection member.
(15) The light-emitting device according to (14), wherein a third wavelength conversion layer is provided on the surface of the inner peripheral reflection member.
(16) The opposing reflecting member is positioned on the side reflecting member side with respect to the straight line passing through the upper end of the inner peripheral surface of the inner peripheral reflecting member on the opposite side of the end portion of the light emitting element. The light emitting device according to any one of (13) to (15).

According to the light emitting device of (1) above, by forming a part of the wavelength conversion material on the side reflecting member as the first wavelength conversion layer, the wavelength conversion material is absorbed in the first wavelength conversion layer. Even if light scattering by the wavelength conversion material occurs, the light changed to fluorescence having another wavelength is reflected in a desired direction (for example, in front of the light emitting element) by a side reflection member present in the vicinity, and light loss is caused. Is suppressed. As a result, in the second wavelength conversion layer formed in the path (for example, in the translucent member) until the light emitted from the light emitting element exits from the light emitting device, the amount of the wavelength converting substance dispersed in the layer Can be reduced, and the optical path length can be shortened and the absorption of light can be suppressed, so that the absorption of light in the optical path is reduced and the light emission efficiency is improved.

According to the light emitting device of (2) above, since the amount of diffusion and reflection on the side reflecting member increases, the amount of excitation light absorbed by the second wavelength conversion layer increases, realizing high light emission characteristics. can do.
According to the light emitting device of (3) above, since the average particle diameter of the second wavelength conversion material contained in the second wavelength conversion layer is 10 nm or less, the wavelength conversion material only exhibits high luminous efficiency. In addition, various emission spectra can be developed depending on the particle size. Therefore, it is possible to realize a light-emitting device with high efficiency and wavelength control.
That is, since the second wavelength conversion layer contains the second wavelength conversion material having an average particle diameter of 10 nm or less, it is much smaller than a quarter of the excitation light wavelength, and thus light scattering hardly occurs. .
Thereby, the luminous efficiency which was excellent with respect to the excitation light of an ultraviolet region is shown, and a high-intensity light-emitting device is realizable.

According to the light emitting device of (4) above, since the thickness of the first wavelength conversion layer is 0.05 to 0.5 mm, the wavelength conversion efficiency of the first wavelength conversion layer is high, and light is transmitted. Since it is sufficiently transmitted, more excellent light emission characteristics can be exhibited. Moreover, it can suppress that the converted light is absorbed by the other fluorescent substance etc. which are contained in the 2nd wavelength conversion layer. Therefore, a highly efficient light emitting device can be realized.
As described in (5) above, when the thickness of the second wavelength conversion layer is increased to 0.1 to 10 mm, the volume fraction of the wavelength conversion substance (that is, the ratio of the wavelength conversion substance to the transparent member) is low. Therefore, the conversion efficiency becomes higher.
According to the light emitting device of (6) above, since the band gap energy of the compound semiconductor material is in the range of 1.5 to 2.5 eV, fluorescence in the visible light region can be obtained. That is, when the particle size is atomized to a nanoscale of 10 nm or less, the band gap increases due to the quantum size effect. At this time, when the band gap energy is 1.5 eV to 2.5 eV, fluorescence in the visible light region in the wavelength range of 400 to 900 nm is obtained, and a light emitting device that emits light with high color rendering and high luminance is obtained.

According to the light-emitting device of (7), the compound semiconductor does not contain harmful semiconductor ultrafine particles such as CdSe and CdS, so it is highly safe and can be applied to various electronic devices. It becomes.
According to the light emitting device of the above (8), since the first wavelength conversion material is an oxide fluorescent material, it is a material that has excellent light resistance and emits high luminance, and thus has excellent light resistance and high luminance emission. The light emitting device is obtained.
According to the light emitting device of (9) above, the wavelength of the output light matches the wavelength of visible light of 400 to 900 nm, so that a white light emitting device with high efficiency and good color rendering is realized.
According to the light emitting device of the above (10), since the peak wavelength of the output light from the first wavelength converting substance is 400 to 700 nm, the light emitted by the phosphor that emits light shorter than its own light emitting wavelength is emitted. It is possible to compensate for the disadvantage of the semiconductor ultrafine particles that the light is absorbed and the luminous efficiency is lowered.
According to the light emitting device of (11) above, since the peak wavelength of the output light from the second wavelength conversion substance is 500 to 900 nm, the output light from the second wavelength conversion layer includes the infrared region, and thus emits light. The efficiency does not decrease, and all output light falls within the visible light wavelength range of 400 to 900 nm. Therefore, a light emitting device with high efficiency and good color rendering can be obtained.
According to the light emitting device of (12) above, when the central wavelength of the excitation light from the light emitting element is 450 nm or less, the quantum efficiency of the wavelength conversion material in the first and second wavelength conversion layers can be improved. , Luminous efficiency can be increased.

According to the light emitting device of the above (13), since the opposed reflecting member is provided, a part of the transmitted light that has passed through the translucent member is reflected by the opposed reflecting member, and the first and second conversions are performed again. Improve the conversion efficiency without increasing the concentration of the wavelength conversion substance in the first and second conversion layers if it is taken into the layer, converted by the wavelength conversion substance in each layer, and emitted to the outside. Can do.
According to the light emitting device of the above (14), since the inner peripheral reflecting member is provided inside the side reflecting member, the light emitted from the light emitting element can be emitted to the outside with high intensity. That is, the light emitted from the light emitting element is reflected upward by the inner peripheral reflecting member, further reflected downward by the counter reflecting member, and a light path that is emitted to the outside is formed by the side reflecting member. Conventionally, light that has traveled in various directions and did not exit to the outside can be satisfactorily emitted to the outside by this configuration, and a highly efficient light-emitting device can be realized.

According to the light emitting device of (15) above, by forming a third wavelength conversion layer on the inner reflection member with a part of the wavelength conversion material, the wavelength conversion material absorbs the third wavelength conversion layer. Even if light scattering by the wavelength conversion material occurs, the light converted into fluorescence having another wavelength is reflected in a desired direction, for example, in front of the light emitting element, by the nearby inner reflection member. Loss is suppressed.
According to the light emitting device of the above (16), the opposing reflecting member has a side surface that is more than a straight line whose outer peripheral portion passes through the end portion of the light emitting element and the upper end of the inner peripheral surface of the inner peripheral reflecting member opposite to the end portion. Since the ratio of reflecting part of the transmitted light that has passed through the second wavelength conversion layer by the opposing reflection member increases because it is located on the reflective member side, the excitation light that has passed through the second wavelength conversion layer Increasing the concentration of the wavelength conversion substance in the first and second conversion layers to be taken into the first and second conversion layers once again, converted by the wavelength conversion substance in each layer, and emitted to the outside. Therefore, the conversion efficiency can be improved. Therefore, the emitted light intensity and brightness can be increased very effectively, and a light emitting device with high luminous efficiency can be realized.

(First embodiment)
The present invention will be described 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.
As shown in FIG. 1, the light emitting device of the present invention includes a substrate 1, a light emitting element 2 including a semiconductor material that emits light having a central wavelength of 450 nm or less on the substrate 1, and light emission around the light emitting element 2. The side reflection member 3 provided so as to efficiently emit the excitation light emitted from the element 2, the first wavelength conversion layer 4 formed on the side reflection member 3, and the light emitting element 2 on the substrate 1. The second wavelength conversion layer 5 is formed so as to cover. The light emitting element 2 is connected to the electrode 6.

  A part of the excitation light L emitted from the light emitting element 2 is absorbed by the second wavelength conversion material 5a while passing through the second wavelength conversion layer 5, and emits the second output light L2. The remaining excitation light L passes through the second wavelength conversion layer 5 a without being absorbed and is injected into the first wavelength conversion layer 4. The injected excitation light L is absorbed by the second wavelength conversion material 5a made of a fluorescent material in the first wavelength conversion layer 4 and emits the first output light L1. The first output light L1 and the second output light L2 are combined to obtain white light Lw.

  Even if light scattering by the wavelength conversion material 5a occurs, the first output light L1 is reflected in a desired direction (for example, in front of the light emitting element) by the side reflecting member 3 present in the vicinity, and light loss is suppressed. . As a result, in the second wavelength conversion layer 5 formed in the path (for example, in the translucent member) until the light emitted from the light emitting element 2 is emitted from the light emitting device, the wavelength conversion dispersed in the layer 5 is performed. Since the amount of the substance 5a can be reduced, the optical path length can be shortened and light absorption can be suppressed, light absorption in the optical path is reduced, and luminous efficiency is improved.

The first wavelength conversion layer 4 is formed by dispersing a first wavelength conversion material 4a made of a fluorescent material having a particle size of 0.1 to 50 μm in the first light transmissive member 4b.
The second wavelength conversion layer 5 is formed by dispersing the second wavelength conversion material 5a made of semiconductor ultrafine particles in the second light transmissive member 5b.

  When three types of phosphors having different emission wavelengths are contained in the same wavelength conversion layer as in a conventional light emitting device, light emitted from the phosphor once is absorbed by another phosphor. The light emission efficiency as a whole of the light emitting device was not sufficiently high.

  On the other hand, in the case of the present invention, the phenomenon that the first wavelength conversion material 4a made of a phosphor absorbs the short wavelength conversion light in the first wavelength conversion layer 4 and the second wavelength conversion layer 5 is described. Even if the concentration of the first wavelength conversion substance 4a in the first wavelength conversion layer 4 is increased and the content is not increased, high conversion efficiency can be obtained. As a result, high light output can be expected with low power consumption.

  As the substrate 1, a substrate having excellent thermal conductivity and a large total reflectivity is used. In addition to ceramic materials such as alumina and nitrogen aluminum, a polymer resin in which metal oxide fine particles are dispersed is preferably used.

The light emitting element 2 preferably emits light having a center wavelength of 450 nm or less, particularly 380 to 420 nm. By using excitation light in the wavelength range of this range, the phosphor can be excited efficiently, the intensity of output light can be increased, and a light emitting device with higher emission intensity can be obtained.
The light emitting element 2 is not particularly limited as long as it emits the central wavelength, but the light emitting element substrate surface has a structure (not shown) including a light emitting layer made of a semiconductor material. This is preferable in that it has a high external quantum efficiency. 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.

The substrate 2 can be selected in consideration of the combination with the light emitting layer. For example, when a light emitting layer made of a nitride semiconductor is formed on the surface, sapphire, spinel, SiC, Si, ZnO, ZrB ₂ , GaN, quartz, etc. These materials are preferably used. In order to form a nitride semiconductor with good crystallinity with high productivity, it is preferable to use a sapphire substrate.

The side reflecting member 3 is formed by performing cutting or molding on a highly reflective metal such as Al, Ag, Au, platinum (Pt), titanium (Ti), chromium (Cr), or Cu. Is done. Alternatively, when the side reflecting member 3 is made of an insulator such as ceramics or resin, a highly reflective metal such as Al, Ag, Au, Pt, Ti, Cr, or Cu is formed on the surface of the insulator by plating or vapor deposition. A thin film may be formed. When the side reflecting member 3 is made of a metal that is easily discolored by oxidation such as Ag or Cu, for example, a Ni plating layer having a thickness of about 1 to 10 μm and an Au plating layer having a thickness of about 0.1 to 3 μm are formed on the surface. It is preferable that the electrodes are sequentially deposited by electrolytic plating or electroless plating. Thereby, the corrosion resistance of the side reflecting member 3 is improved and the deterioration of the reflectance is suppressed.
The side reflecting member 3 is preferably a so-called mortar type as shown in FIG. 1, but can be formed into an arbitrary shape so that the excitation light can be reflected in a desired direction, if necessary.

  The wavelength conversion material 4 a made of a fluorescent material contained in the first wavelength conversion layer 4 and the wavelength conversion material 5 a made of semiconductor ultrafine particles contained in the second wavelength conversion layer 5 are directly emitted by light emitted from the light emitting element 2. When excited, the wavelengths of these lights are synthesized, covering the emission wavelength in a wide range, and the color rendering can be greatly improved. Thus, the peak wavelength of the synthesized white light Lw of the output light obtained from each wavelength conversion layer is preferably 400 to 900 nm, particularly 450 to 850 nm, and more preferably 500 to 800 nm.

  The output lights L1 and L2 are preferably 500 to 900 nm and 400 to 700 nm, respectively. As a result, the emission wavelength can be covered in a wide range, and the color rendering can be further improved.

  The wavelength conversion material 5a made of semiconductor ultrafine particles in the second wavelength conversion layer 5 may be made of a plurality of particles having different fluorescence spectra. In this case, the two or more types of semiconductor ultrafine particles may have different semiconductor compositions, or may have the same composition and different particle sizes.

The first wavelength conversion material 4a in the first wavelength conversion layer 4 may be composed of a plurality of materials having different fluorescence spectra.
The manufacturing method of the 1st wavelength conversion layer 4 and the 2nd wavelength conversion layer 5 is the 1st wavelength conversion material 4a which consists of each fluorescent substance shown previously, and the 2nd wavelength conversion material 5a which consists of semiconductor ultrafine particles. Are preferably dispersed and formed in the first translucent member 4b and the second translucent member 5b made of a polymer resin film, respectively.

  As the translucent member, a polymer resin film that can easily disperse and carry the phosphor uniformly and can suppress light deterioration of the phosphor is used. The material of such a 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 Furthermore, derivatives of these materials are used. In particular, it is preferable to use a translucent member having a light transmittance of 95% or more in a wavelength region of 350 nm or more. In addition to such translucency and transparency, epoxy resins and silicone resins are more preferably used from the viewpoint of heat resistance. In the case of a silicone resin, it is not particularly limited whether it is linear or has a crosslinked structure. Substituents on silicon are methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, n-pentyl group, cyclopentyl group, n-hexyl group, cyclohexyl group, octyl group, Hydrocarbon groups containing aromatic hydrocarbon groups such as alkyl groups having about 1 to 20 carbon atoms such as decyl group, dodecyl group, hexadecyl group, octadecyl group, phenyl group, benzyl group, naphthyl group, naphthylmethyl group, etc. Among them, a linear alkyl group having a small number of carbon atoms such as a methyl group and an ethyl group is preferable.

  Further, a mixture of the second wavelength converting material 5b made of ultrafine semiconductor particles and an uncured matrix resin to be the second light-transmissive member 5a is formed into a sheet shape. As the forming method, a forming method capable of forming a sheet, such as a doctor blade method, a die coater method, an extrusion method, a spin coating method, or a dip method, can be used, and a doctor blade method or a die coater method is desirable in terms of productivity.

Next, the wavelength conversion layer 5 containing the second wavelength conversion material 5b made of ultrafine semiconductor particles is B-staged and then cured. By curing in the B-stage state, adhesion is improved and peeling between the sheet layers after curing can be prevented. Further, the thermocompression bonding and curing steps may be performed separately, but it is preferable to perform them continuously in that they can be produced in a short time.
The wavelength converting material 5a made of semiconductor ultrafine particles contained in the second wavelength converting layer 5 is composed of Group Ib, Group II (excluding Be, Cd, Hg, Ra), Group III of the periodic table. (Excluding Tl and Ac series elements), Group IV (excluding Pb and Hf), Group V (excluding As and Pa series), Group VI (excluding Se and U) The semiconductor ultrafine particles composed of at least two kinds of elements belonging to (1) are not particularly limited. For example, BN, BP, BAs, AlN, AlP, AlSb, GaN, GaP, GaSb, InN, InP, InSb and other III-V group compound semiconductors, ZnO, ZnS and other II-VI group compound semiconductors, CuInS ₂ , CuGaS ₂ , CuAlS ₂ , Cu (In _1-x Al _x ) S ₂ , CuInS ₂ , Cu (In _1-x Ga _x ) S ₂ (x and y are 0 ≦ x ≦ 1, 0 ≦ y, respectively) A value represented by ≦ 1) is preferably used.

The particle diameter of the second wavelength converting material 5a made of the ultrafine semiconductor particles of the present invention is preferably 10 nm or less, particularly preferably 2 nm to 10 nm.
Furthermore, the second wavelength converting material 5a comprising the semiconductor ultrafine particles of the present invention has a band gap energy of 1.5 to 2.5 eV at a temperature of 300 K in the compound semiconductor in the bulk state of the semiconductor composition constituting the second wavelength converting material 5a. A range is preferable.

  Further, the second wavelength converting material 5a made of semiconductor ultrafine particles in the present invention may have a so-called core-shell structure made of an inner core (core) and an outer shell (shell). The core-shell type semiconductor nanoparticles 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 forbidden band width (band gap) larger 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.

  The composition of the semiconductor material suitably used for the shell depends on the band gap of the core semiconductor crystal, but the band gap in the bulk state is 2.5 eV or more at a temperature of 300 K, such as BN, BAs, GaN, GaP, etc. III-V group compound semiconductors, II-VI group compound semiconductors such as ZnO and ZnS, and compounds of Group 2 elements of the periodic table and Group 16 elements of the periodic table such as MgS and MgSe are preferably used.

Further, the second wavelength converting material 5a made of semiconductor ultrafine particles in the present invention may be covered with a surface modifying molecule made of an organic ligand. By covering the surface modification molecules, aggregation of the second wavelength conversion material 5a made of semiconductor ultrafine particles can be suppressed, and the function of the semiconductor ultrafine particles can be expressed to the maximum. 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 hydrocarbon compounds having 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, among which an n-hexyl group, A hydrocarbon compound having a linear alkyl group having about 6 to 16 carbon atoms such as an octyl group, a decyl group, a dodecyl group, a hexadecyl group and the like is 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 An organic compound 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 hydroxyl group, a carbonyl group, an ester bond, an ether bond, or a polyethylene glycol chain is preferable. .
Specific examples of such surface modifying molecules include oleylamine, octadecylamine, oleic acid, mercapto-modified silicone, amine-modified silicone, carboxyl-modified silicone and the like.

In addition, the second wavelength converting material 5a made of semiconductor ultrafine particles in the present invention is manufactured by a general manufacturing method. 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, the microreactor method, the microwave heating method and the like are used.
The first wavelength conversion substance 4a made of a fluorescent substance in the present invention is not particularly limited as long as it is a material that is excited by light of 450 nm or less and emits light in the range of 400 to 700 nm. As the first wavelength conversion material 4a made of a fluorescent material, a generally used phosphor can be adopted. For example, (Ba, Eu) MgAl ₁₀ O ₁₇ , (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ Cl ₁₇ : Eu, Sr ₁₀ (PO ₄ ) ₆ Cl ₁₂ : Eu, (Ba, Sr, Eu _{) (Mg, Mn) Al 10} O 17, 10 (Sr, Ca, Ba, Eu) · 6PO 4 · Cl 2, BaMg 2 Al 16 O 25: Eu, Y 3 Al 5 O 12: Tb, Y3 (Al, Ga) ₅ O ₁₂ : Tb, Y ₂ SiO ₅ : Tb, Zn ₂ SiO ₄ : Mn, ZnS: Cu + Zn ₂ SiO ₄ : Mn, Gd ₂ O ₂ S: Tb, (Zn, Cd) S: Ag, Y ₂ O ₂ S: Tb, ZnS: Cu, Al + In ₂ O ₃ , (Zn, Cd) S: Ag + In ₂ O ₃ , (Zn, Mn) ₂ SiO ₄ , BaAl ₁₂ O ₁₉ : Mn, (Ba, Sr, Mg) O.aAl ₂ O ₃ : Mn, LaPO ₄ : Ce, Tb, 3 (Ba, Mg, Eu, Mn) O. 8Al ₂ O ₃ , La ₂ O ₃ .0.2SiO ₂ .0.9P ₂ O ₅ : Ce, Tb, CeMgAl ₁₁ O ₁₉ : Tb, Y ₂ O ₂ S: Eu, Y ₂ O ₃ : Eu, Zn ₃ (PO ₄ ) ₂ : Mn, (Zn, Cd) S: Ag + In ₂ O ₃ , (Y, Gd, Eu) BO ₃ , (Y, Gd, Eu) ₂ O ₃ , YVO ₄ : Eu, La ₂ O ₂ S: Eu, Sm, YAG: Ce, etc. are used. The first wavelength converting material 4a preferably has a particle size of 0.1 to 50 μm, particularly 1 μm to 20 μm.

  The thickness of the second wavelength conversion layer 5 is preferably 0.5 to 10 μm, particularly preferably 1.0 to 5 mm, from the viewpoint of conversion efficiency and ultraviolet and visible light transmittance. Furthermore, the thickness of the first wavelength conversion layer 4 is preferably 0.05 to 0.5 mm, particularly preferably 0.1 to 0.3 mm. Within this range, the excitation light L emitted from the light emitting element can be converted into the output lights L1 and L2 with high efficiency, and the converted output lights L1 and L2 can be transmitted to the outside with high efficiency. .

(Second Embodiment)
Another embodiment of the present invention will be described with reference to FIG. FIG. 2 is a schematic sectional view showing still another embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same component as FIG. 1, and description is abbreviate | omitted.
As shown in FIG. 2, the light emitting device of this embodiment includes a side reflecting member 3 provided around the light emitting element 2 so that excitation light emitted from the light emitting element 2 is efficiently emitted forward, and the side reflecting member 3. The first wavelength conversion layer 4 formed above, the second wavelength conversion layer 5 formed on the substrate 1 so as to cover the light emitting element 2, and a part of the second wavelength conversion layer 5 are covered. The counter reflecting member 8 and an inner peripheral reflecting member 9 provided around the light emitting element 2 so as to surround the light emitting element 2 inwardly of the side surface reflecting member 3.

  As a result, light emitted from the light emitting element is reflected upward by the inner peripheral reflecting member, further reflected downward by the counter reflecting member, and a light path that is emitted to the outside is formed by the side reflecting member. Conventionally, light that has traveled in various directions and did not exit to the outside can be satisfactorily emitted to the outside by this configuration, and a highly efficient light-emitting device can be realized.

The counter reflecting member 8 is formed in a plate shape and has a light reflecting surface 8 a that faces the excitation light emitting surface of the light emitting element 2.
In the first wavelength conversion layer 4, an oxide fluorescent material having a particle size of 0.1 to 50 μm or a first wavelength conversion material 4 a made of semiconductor ultrafine particles having a particle size of 10 nm or less is formed on the first light transmitting member 4 b. Is distributed.
In the second wavelength conversion layer 5, a second wavelength conversion material 5a made of semiconductor ultrafine particles is dispersed in the second transparent member 5b.

The material of the counter-reflecting material 8 is a metal, resin, ceramic, or the like that has a high reflectance in the near ultraviolet to visible light region. Examples of materials include aluminum for metals, polyester and polyolefin for resins, and alumina ceramics for ceramics. Alternatively, Ag or Au may be deposited on the surface of a substrate made of metal, resin, ceramic, or the like by a thin film forming method such as plating or vapor deposition to form a counter reflector.
When the counter-reflecting material 8 is made of, for example, an aluminum plate, aluminum is formed into a disk shape or the like by punching or cutting, and a light scattering material such as barium sulfate or titanium oxide is contained on the surface of the resin to form a mist. By applying to the counter reflector, a counter reflector having a light scattering surface with a high reflectance can be formed.

The inner periphery reflecting member 9 is formed on the inner periphery side of the side surface reflecting member 3 so as to surround the light emitting element. The inner peripheral reflecting member 9 can be formed using the same material as the side reflecting member 3.
Further, the opposing reflection member 8 has an outer peripheral portion positioned closer to the side reflection member 3 than a straight line A passing through the end of the light emitting element 2 and the inner peripheral surface upper end of the inner peripheral reflection member 9 on the opposite side of the end. It is preferable to increase luminous efficiency. That is, in order to reflect a part of the transmitted light that has passed through the second wavelength conversion layer 5 by the opposing reflection member 8, the excitation light that has passed through the second wavelength conversion layer 8 is once again converted into the first and second conversion layers. 4 and 5 are converted into wavelength conversion materials 4a and 5a in the respective layers 4 and 5 and emitted to the outside (light reflection paths are exemplified by arrows B1, B2 and B3). Conversion efficiency can be improved without increasing the concentration (content) of the wavelength converting substances 4a and 5a in the second conversion layers 4 and 5.

  As shown in FIG. 3, the light emitting device of this embodiment preferably includes a third wavelength conversion layer 7 on the surface of the inner peripheral reflection member 9. That is, the light-emitting device of this embodiment emits light from the light-emitting element 2 around the light-emitting element 2 and the light-emitting element 2 including a semiconductor material that emits light having a central wavelength of 450 nm or less on the substrate 1. A side reflection member 3 provided to efficiently emit excitation light forward, a first wavelength conversion layer 4 formed on the side reflection member 3, and a light emitting element 2 on the substrate 1 The formed second wavelength conversion layer 5, the inner peripheral reflection member 9 provided so as to surround the light emitting element inwardly of the side surface reflection member 3, and a third wavelength on the surface of the inner peripheral reflection member 9 The conversion layer 7 is preferably included.

  The third wavelength conversion layer 7 is formed by dispersing a third wavelength conversion material 7 a made of a fluorescent material having a particle size of 0.1 to 50 μm or semiconductor ultrafine particles in the light transmitting member 7 b. The third wavelength converting substance 7a may be the same as or different from the first wavelength converting substance 4a and the second wavelength converting substance 5a.

  By providing the third wavelength conversion layer 7 on the surface of the inner peripheral reflection member 9 in this way, the area on which the excitation light is irradiated to the wavelength conversion layer becomes larger than usual, so the dispersion concentration of the phosphor does not have to be increased. Also, the conversion efficiency can be improved. Further, although the irradiation area of the excitation light is increased, the module size does not have to be increased, so that a small and highly efficient light emitting device can be realized.

  In addition, even if it is only any one of the opposing reflective material 8 and the internal peripheral reflection member 9, it is effective in improving luminous efficiency.

(Semiconductor ultrafine particles)
The average particle diameter of the used semiconductor ultrafine particles was confirmed by a transmission electron microscope (TEM). The transmission electron microscope used was JEOL JEM2010F, and an acceleration voltage of 200 kV was observed according to the following procedure. That is, the semiconductor ultrafine particles were placed in a sample bottle, and isopropyl alcohol (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 TEM observation microgrid, dried, and then set on 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 large amount of phosphor is attached is not suitable for measurement of the average particle diameter because the particles overlap in the direction of the electron beam. Further, the phosphor adhering to the Cu mesh portion of the microgrid is 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, when many organic components used at the time of synthesis remain around the phosphor, the lattice image is blurred, and thus 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 at the time of synthesis is performed by adding chloroform, toluene or hexane to the precipitated phosphor and dispersing it with ultrasonic waves, and then adding alcohol (for example, ethanol) thereto and centrifuging it. be able to. The organic components at the time of synthesis are dissolved in the supernatant ethanol, and the phosphor is 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 phosphor was determined by processing according to the following method based on the diameter of 200 photographed lattice images.
The length average diameter was calculated by statistically calculating the diameter of the measured lattice image by writing 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 measured grid images (average Particle shape and calculation formula, “Ceramic manufacturing process” p.11-12, edited by ceramic industry association editorial committee lecture subcommittee). The length average diameter thus calculated was regarded as the average particle diameter of the phosphor.

(Other than semiconductor ultrafine particles)
The average particle diameter (0.1 μm to 50 μm) of the wavelength converting substance other than the semiconductor ultrafine particles was measured using a laser diffraction scattering method. That is, the measurement was performed using a microtrack (9320-X100) manufactured by Nikkiso Co., Ltd. As a dispersion medium, 2-propanol was used and dispersed with an ultrasonic homogenizer (ultrasonic output: 300 to 400 μA, irradiation time 6 minutes).

  Hereinafter, the light emitting device of the present invention will be described with reference to examples, but the present invention is not limited to the following examples.

The light emitting device of FIG. 1 was produced. First, a light emitting element made of a nitride semiconductor was formed on a light emitting element substrate made of sapphire by metal organic vapor phase epitaxy.
The structure of the light-emitting element is an n-type GaN layer that is an undoped nitride semiconductor on a light-emitting element substrate, a GaN layer that is an n-type contact layer formed with an Si-doped n-type electrode, and an n-type nitride semiconductor that is an undoped nitride semiconductor. 5 layers of InGaN layers sandwiched between GaN layers, each comprising a type GaN layer, a GaN layer that constitutes a light emitting layer, a InGaN layer that constitutes a well layer, and a GaN layer that constitutes a barrier layer A multiple quantum well structure was adopted.
This light emitting element was mounted on a substrate made of alumina by a flip chip mounting method. On the other hand, a side reflecting member made of aluminum is provided around the light emitting element 2, and (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) _{6 Cl 2} : Eu, BaMgAl ₁₀ is provided on the inner peripheral surface of the side reflecting member. A silicone resin containing 20% by mass of O ₁₇ : Eu, Mn was applied to form a first wavelength conversion layer having a thickness of 0.2 mm.
Further, a silicone resin in which 0.5% by mass of semiconductor ultrafine particles CuGa _0.5 In _0.5 S ₂ (band gap energy: 2.0 eV) is dispersed is applied with a dispenser so as to cover the light emitting element, and a second 5 mm thick second resin is applied. A wavelength conversion layer was prepared. The surface of this second wavelength conversion layer is circular with a diameter of 10 mm. In addition, the said semiconductor ultrafine particle mixed the same amount of particles with a particle size of 2.5 nm and 3.5 nm.
The light emitting characteristics of the obtained light emitting device were evaluated. As a result, it was found that the color rendering property Ra85 and the luminous efficiency of 60 lm / W were high. The color rendering property Ra and the light emission efficiency were measured by a fluorescence measurement system MCPD-7000 (manufactured by Otsuka Electronics Co., Ltd.).

A light emitting device was obtained in the same manner as in Example 1 except that an aluminum plate having a diameter of 7 mm was placed as a counter reflecting plate at the center of the surface of the second wavelength conversion layer covering the light emitting element.
The light emitting characteristics of the obtained light emitting device were evaluated in the same manner as in Example 1. As a result, it was found that the color rendering property Ra92 and the luminous efficiency of 72 lm / W were very high.

In Example 2, a light emitting device was obtained in the same manner as Example 2 except that an inner peripheral reflecting member made of aluminum was provided inward of the side reflecting member so as to surround the light emitting element. At this time, as shown by a one-dot chain line A in FIG. 2, the inner peripheral reflecting member is a straight line whose outer peripheral portion passes through the end of the light emitting element and the upper end of the inner peripheral surface of the inner peripheral reflecting member opposite to the end. It is located on the side reflecting member side.
The light emitting characteristics of the obtained light emitting device were evaluated in the same manner as in Example 1. As a result, it was found that the color rendering property Ra90 and the luminous efficiency of 70 lm / W were very high.

In Example 3, a light emitting device was obtained in the same manner as in Example 3 except that a third wavelength conversion layer containing a fluorescent material was provided on the inner peripheral reflecting member surface. That is, silicone containing 20% by mass of (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) _{6 Cl 2} : Eu, BaMgAl ₁₀ O ₁₇ : Eu, Mn on the inner peripheral surface of the inner peripheral reflecting member in terms of solid matter. Resin was applied to form a third wavelength conversion layer having a thickness of 0.1 mm.
The light emitting characteristics of the obtained light emitting device were evaluated in the same manner as in Example 1. As a result, a lamp efficiency of color rendering property Ra90 and luminous efficiency of 75 lm / W was obtained. By providing the wavelength conversion layer on the inner peripheral reflection surface, the luminous efficiency could be improved without increasing the device size.

It is a schematic sectional drawing which shows one Embodiment of the optical apparatus of this invention. It is a schematic sectional drawing which shows other embodiment of the light-emitting device of this invention. It is a schematic sectional drawing which shows other embodiment of the light-emitting device of this invention. It is a schematic sectional drawing which shows the conventional light-emitting device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Light emitting element 3 ... Side reflection member 4 ... First wavelength conversion layer 5 ... Second wavelength conversion layer 4a ... First wavelength conversion substance 4b .... First translucent member 5a ... second wavelength converting material 5b ... second translucent member 6 ... electrode 8 ... opposite reflecting member 9 ... inner peripheral reflecting member

Claims (16)

Side-surface reflection provided with a substrate, a light-emitting element that emits excitation light mounted on the substrate, and an inner wall surface that surrounds the light-emitting element and surrounds the light-emitting element and reflects the excitation light in a desired direction A member, a first wavelength conversion layer formed on the inner wall surface of the side-surface reflection member, and a second wavelength conversion layer formed in a path until light emitted from the light emitting element is emitted from the light emitting device. A light emitting device comprising the light emitting device. 2. The light emitting device according to claim 1, wherein the first wavelength conversion layer is formed by including a first wavelength conversion material having an average particle diameter of 0.1 to 50 μm in a translucent member. apparatus. The second wavelength conversion layer is formed by containing a second wavelength conversion material, which is a compound semiconductor having an average particle diameter of 10 nm or less, in a translucent member. Light-emitting device. The light emitting device according to any one of claims 1 to 3, wherein the first wavelength conversion layer has a thickness of 0.05 to 0.5 mm. 5. The light emitting device according to claim 1, wherein the second wavelength conversion layer has a thickness of 0.1 to 10 mm. The light emitting device according to claim 3, wherein a band gap energy of the compound semiconductor material is in a range of 1.5 to 2.5 eV. The compound semiconductor is composed of Group Ib, Group II (excluding Be, Cd, Hg, Ra), Group III (excluding Tl, Ac series elements), Group IV (excluding Be, Cd, Hg, Ra). However, it has a semiconductor composition composed of at least two elements belonging to Group V (excluding As and Pa series), Group VI (excluding Se and U), excluding Pb and Hf) The light-emitting device according to claim 3 or 6. The light emitting device according to claim 2, wherein the first wavelength converting substance is an oxide fluorescent substance. The first output light converted by the first wavelength conversion layer and the second output light converted by the second wavelength conversion layer are mixed to emit white light having a spectrum of 400 to 900 nm. The light-emitting device according to claim 1. The light emitting device according to claim 1, wherein a peak wavelength of output light from the first wavelength conversion layer is 400 to 700 nm. 11. The light emitting device according to claim 1, wherein a peak wavelength of output light from the second wavelength conversion layer is 500 to 900 nm. The light emitting device according to any one of claims 1 to 11, wherein a central wavelength of excitation light emitted from the light emitting element is 450 nm or less. The counter reflection member which has a light reflection surface which covers a part of said 2nd wavelength conversion layer, and opposes the excitation light emission surface of the said light emitting element is comprised. The light-emitting device of description. The light-emitting device according to claim 1, wherein an inner peripheral reflection member is provided so as to surround the light-emitting element inward of the side surface reflection member. The light emitting device according to claim 14, wherein a third wavelength conversion layer is provided on a surface of the inner peripheral reflection member. The counter reflecting member has an outer peripheral portion positioned on the side reflecting member side with respect to a straight line passing through an end of the light emitting element and an upper end of the inner peripheral surface of the inner peripheral reflecting member on the opposite side of the end. The light-emitting device according to claim 13.

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