Resin Composition, Optical Element, and Ultraviolet Light Emitting Device

Abstract

The present invention pertains to a resin composition containing metal oxide nanoparticles dispersed in a resin and used for an ultraviolet light emitting device, wherein the refractive index nd(C) of the resin composition and the refractive index nd(R) of the resin with respect to the d-line (wavelength 587.6 nm) satisfy the relationship nd(C)-nd(R)≥0.03.

Description

Technical Field

[0001] The present invention relates to a resin composition, an optical element, and an ultraviolet light-emitting device.

Background Art

[0002] As a light source in an ultraviolet light-emitting device, from the viewpoint of environmental protection and the like, an ultraviolet LED element (light-emitting diode element) of a semiconductor light-emitting element has been attracting attention instead of a conventional mercury lamp. This ultraviolet LED element is used in various applications depending on the emission wavelength. For example, it can be used in the curing process of ultraviolet-curable resins, the treatment of skin diseases, and the sterilization of viruses and pathogenic bacteria.

[0003] However, in the ultraviolet LED element, only a part of the light generated in the active layer of the LED element and taken out to the outside of the ultraviolet LED element can be utilized, so the light extraction efficiency is low, which has hindered its widespread use. In order to improve the light extraction efficiency, ultraviolet LED elements such as flip-chip structures and vertical structures have been studied, but the light extraction efficiency is still as low as about several percent, and further improvement in the light utilization efficiency is required.

[0004] On the other hand, Patent Document 1 discloses a technique of forming a photonic crystal having an uneven structure by etching on the light-emitting surface of an LED element to extract a part of the total-reflected light outside the LED. In addition, techniques of providing an optical member on an LED element have also been studied. As the optical member, Patent Document 2 discloses a technique of using a hemispherical lens made of sapphire, Patent Document 3 discloses a technique of using a spinel sintered body, and Patent Document 4 discloses a technique of using a fluororesin.

[0005] Regarding the study of a material for bonding a semiconductor light-emitting element such as an ultraviolet LED element and an optical member, Patent Document 5 discloses a technique of using a resin having translucency as a member for bonding a light-emitting element and a coating member. Further, Patent Document 6 discloses a technique of using a thermoplastic resin or a curable resin as a material for forming an adhesive member.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0007] Thus, technologies for improving the light extraction efficiency by combining an optical member with a semiconductor light-emitting element have been studied and proposed from various angles. However, not much study has been made on the material for bonding the semiconductor light-emitting element and the optical member. According to the studies by the present inventors, for example, when using a resin as disclosed in Patent Documents 5 and 6 as an adhesive material, it has been found that the light extraction efficiency decreases due to the low refractive index of the resin. This is considered to be because a lot of light is reflected at the interface between the semiconductor light-emitting element and the resin, and the light is not radiated to the outside of the semiconductor light-emitting element.

[0008] Therefore, an object of the present invention is to provide a resin composition having a high refractive index and excellent light extraction efficiency when used in an ultraviolet light-emitting device. Another object is to provide an optical element including a resin composition layer of such a resin composition, and an ultraviolet light-emitting device having the optical element.

Means for Solving the Problems

[0009] As a result of intensive studies by the present inventors, it has been found that the above problems can be solved by a resin composition in which specific metal oxide nanoparticles are dispersed in a resin, and the present invention has been completed.

[0010] That is, the present invention and one aspect thereof relate to the following [1] to

[23] . [1] A resin composition in which metal oxide nanoparticles are dispersed in a resin, The refractive index n of the resin composition with respect to d-line (wavelength 587.6 nm) d (C) and the refractive index n of the resin d (R) satisfy the relationship of n d (C) - n d (R) ≧ 0.03, and the resin composition is used for an ultraviolet light emitting device. [2] The resin composition according to [1], wherein the band gap of the metal oxide nanoparticles is 4.8 eV or more. [3] The resin composition according to [1] or [2], wherein the metal oxide nanoparticles contain at least one kind of nanoparticles selected from the group consisting of Gd2O3, HfO2, La2O3, Y2O3, Yb2O3, ZrO2, Al2O3, and SiO2. [4] The resin composition according to any one of [1] to [3], wherein the average primary particle diameter of the metal oxide nanoparticles is 2 to 80 nm. [5] The resin composition according to any one of [1] to [4], wherein the content of the metal oxide nanoparticles is 15% by mass or more and 70% by mass or less. [6] The resin composition according to any one of [1] to [5], wherein the refractive index n of the resin composition d (C) is 1.39 or more. [7] The resin composition according to any one of [1] to [6], wherein the average value of the transmittance in the wavelength range of 260 to 400 nm is 70% or more. [8] The resin composition according to any one of [1] to [7], wherein the resin is at least one of a fluororesin and a silicone resin. [9] The ultraviolet light emitting device includes a semiconductor light emitting element having a peak wavelength λ(D) in the wavelength range of 250 to 400 nm and an optical member, The resin composition according to any one of [1] to [8], which is used for adhesion between the light emitting surface of the semiconductor light emitting element and the optical member.

[10] An optical element comprising a resin composition layer and an optical member that transmits ultraviolet light, wherein the resin composition layer is made of a resin composition in which metal oxide nanoparticles are dispersed in a resin, The refractive index n of the resin composition layer with respect to the d-line (wavelength 587.6 nm) d (C)' and the refractive index n of the resin d (R) satisfy the relationship n d (C)' - n d (R) ≥ 0.03, An optical element for an ultraviolet light emitting device, in which the resin composition layer is formed on at least a partial region of the surface of the optical member.

[11] The refractive index n of the optical member with respect to the d-line (wavelength 587.6 nm) d (O) and the refractive index n of the resin composition layer d (C)' satisfy Δn d = |n d (O) - n d (C)'| ≤ 0.35, the optical element according to

[10] above.

[12] The optical element according to

[10] or

[11] above, wherein the optical member is made of quartz, sapphire, or spinel.

[13] The optical member is made of inorganic glass, and the inorganic glass is an ultraviolet highly transmissive glass having a maximum absorption coefficient αmax of 0.2 mm in the wavelength range of 260 to 400 nm -1 or less, the optical element according to

[10] or

[11] above.

[14] The optical element according to any one of

[10] to

[13] above, wherein the ultraviolet light emitting device includes a semiconductor light emitting element having a peak wavelength λ(D) in the wavelength range of 250 to 400 nm.

[15] The optical element according to

[14] above, wherein the resin composition layer is used for adhesion between the light emitting surface of the semiconductor light emitting element and the optical member.

[16] An ultraviolet light emitting device having a substrate, a semiconductor light emitting element provided on the substrate, and an optical element provided on the semiconductor light emitting element, wherein: The optical element includes a resin composition layer and an optical member that transmits ultraviolet light. The resin composition layer is made of a resin composition in which metal oxide nanoparticles are dispersed in a resin. The refractive index n d (C)' of the resin composition layer with respect to the d-line (wavelength 587.6 nm) and the refractive index n d (R) of the resin satisfy the relationship n d (C)' - n d (R) ≥ 0.03. The resin composition layer is formed in at least a part of the surface region of the optical member. An ultraviolet light emitting device in which the optical element is provided via the resin composition layer on the light emitting surface of the semiconductor light emitting element.

[17] The ultraviolet light emitting device according to

[16] , wherein the peak wavelength λ(D) of the light emitted by the semiconductor light emitting element is in the wavelength range of 250 to 400 nm.

[18] The ultraviolet light emitting device according to

[17] , wherein the refractive index n o (C)' of the resin composition layer at the peak wavelength λ(D) is 1.4 or more.

[19] The ultraviolet light emitting device according to

[17] or

[18] , wherein the refractive index n o (O) of the optical member and the refractive index n o (C)' of the resin composition layer satisfy the relationship Δn o = |n o (O) - n o (C)'| ≤ 0.42.

[20] The ultraviolet light emitting device according to any one of

[16] to

[19] , wherein the adhesive strength between the light emitting surface of the semiconductor light emitting element and the optical member by the resin composition layer is 5 N / mm or more in shear strength. 2

[21] The ultraviolet light emitting device according to any one of

[16] to

[20] , wherein the semiconductor light emitting element has a flip chip structure or a vertical structure.

[22] The ultraviolet light emitting device according to any one of

[16] to

[21] , wherein the resin composition layer covers at least a part of the side surface of the semiconductor light emitting element.

[23] The ultraviolet light emitting device according to any one of

[16] to

[22] , wherein a part of the optical member is in contact with the substrate or adhered to the substrate. [Advantages of the Invention]

[0011] According to the present invention, by dispersing metal oxide nanoparticles in a resin, a resin composition having a high refractive index can be provided. By using this in an ultraviolet light emitting device having a semiconductor light emitting element, reflection of light at the interface between the semiconductor light emitting element and the resin composition can be suppressed, and a large amount of light can be radiated to the outside of the semiconductor light emitting element. Therefore, the output of the ultraviolet light emitting device can be improved. [Brief Description of the Drawings]

[0012]

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Figure 16

DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented without departing from the gist of the present invention. In addition, "~" indicating a numerical range is used in the sense of including the numerical values described before and after as the lower limit value and the upper limit value.

[0014] [Resin Composition] The resin composition according to the present embodiment contains a resin and metal oxide nanoparticles, and the metal oxide nanoparticles are dispersed in the resin. By dispersing the metal oxide nanoparticles, the refractive index of the resin composition can be made higher than that of the resin. The refractive index has wavelength dispersibility and is represented by the following Cauchy dispersion formula. n(λ)=A+(B / λ 2 )+(C / λ 4 ) In the formula, λ represents the wavelength of light, and n(λ) represents the refractive index with respect to the light of wavelength λ. A, B, and C are constants determined experimentally. When the resin composition is used in an ultraviolet light emitting device, the refractive index in the ultraviolet wavelength range is important. In this specification, for convenience, the refractive index at the d-line (wavelength 587.6 nm) is used. By increasing the refractive index at this d-line, the refractive index in the ultraviolet wavelength range can also be increased.

[0015] When the refractive index of the resin composition with respect to the d-line (wavelength 587.6 nm) is n d (C), and the refractive index of the resin is n d (R), when n d (C) - n d (R) ≥ 0.03 is satisfied, and it is used in an ultraviolet light emitting device. Incidentally, the refractive index with respect to the d-line may be simply referred to as the d-line refractive index hereinafter.

[0016] By using an organic-inorganic composite material in which metal oxide nanoparticles are dispersed in a resin, the d-line refractive index n d (C) of the resin composition can be increased. The higher the d-line refractive index n d (C) of the resin composition, the higher the refractive index in the ultraviolet wavelength range, and the higher the output of the ultraviolet light emitting device. The improvement of the d-line refractive index n d (C) of the resin composition due to using the organic-inorganic composite material can be represented by the difference from the d-line refractive index n d (R) of the resin. That is, the difference in the d-line refractive index represented by n d (C) - n d (R) is 0.03 or more, preferably 0.05 or more, and more preferably 0.1 or more. The upper limit of the difference in the d-line refractive index is not particularly limited, but is usually 1 or less.

[0017] By increasing the d-line refractive index n d (C) of the resin composition, total reflection and Fresnel reflection at the interface between the light emitting surface of the semiconductor light emitting element and the resin composition, and at the interface between the optical member and the resin composition can be suppressed, and a decrease in the light extraction efficiency can be suppressed. As a result, the output of the ultraviolet light emitting device can be improved. Therefore, the d-line refractive index n d (C) of the resin composition is preferably 1.39 or more, preferably 1.4 or more, and more preferably 1.45 or more. The d-line refractive index n d(C) has no particular upper limit, but from the viewpoint of the balance between the adhesiveness of the optical element and the optical member and the improvement of the output of the ultraviolet light emitting device, it is usually 1.6 or less. The d-line refractive index n of the resin composition d (C) can be adjusted by increasing or decreasing the amount of metal oxide nanoparticles.

[0018] The average value of the transmittance (average transmittance) in the wavelength range of 260 to 400 nm of the resin composition is preferably 70% or more, more preferably 75% or more, from the viewpoint of achieving high output of the ultraviolet light emitting device. Also, the higher the average transmittance, the more preferable it is, but it is usually 100% or less. In addition, the transmittance of light at each wavelength in this specification is a value measured using a visible ultraviolet spectrophotometer. That is, the transmittance is the external transmittance including the surface reflectance at the interface, not the internal transmittance, and is the external transmittance converted to a thickness of 10 μm.

[0019] The resin composition is used in an ultraviolet light emitting device, and is preferably used in an ultraviolet light emitting device including a semiconductor light emitting element having a peak wavelength λ(D) in the wavelength range of 250 to 400 nm. Since the light extraction efficiency becomes lower in a semiconductor light emitting element that emits short-wavelength ultraviolet light, it is more preferably used in an ultraviolet light emitting device including a semiconductor light emitting element having a peak wavelength in the wavelength range of 250 to 370 nm, still more preferably 250 to 330 nm, and particularly preferably 250 to 290 nm. Also, it is preferably used between the optical member and the semiconductor light emitting element in the ultraviolet light emitting device, and more preferably used for adhesion. Adhesion does not necessarily require a strong adhesive strength only with the resin composition. By using another adhesive at a location other than the optical path, for example, at the interface between the substrate of the ultraviolet light emitting device and the optical member, high light extraction efficiency and adhesive strength may be achieved simultaneously. Details of the ultraviolet light emitting device will be described later.

[0020] When two members, i.e., adherends, are adhered together with a resin composition, for example, the resin composition is heated to a temperature above its softening point to be softened and brought into contact with the two adherends to be adhered. Then, by cooling and curing, the two adherends are adhered to each other via the resin composition layer. Also, when using a thermosetting resin, a photocurable resin, etc., the resin composition is applied to the adhesion surface of at least one of the adherends, and after the adherends are bonded together, heat or light is irradiated to cure them, so that the two adherends are adhered to each other via the resin composition layer.

[0021] As the adherends, an optical member and a semiconductor light-emitting element in an ultraviolet light-emitting device are preferable, but the resin composition according to the present embodiment is not excluded from being used for bonding other members. In the case of other members, members that require light transmissibility are preferable, and examples include bonding of glass fibers to each other, bonding of lenses to each other, bonding of prisms to each other, bonding of optical filters to each other, etc.

[0022] (Metal oxide nanoparticles) The band gap of the metal oxide nanoparticles preferably is 4.8 eV or more so as not to have absorption on the longer wavelength side than a wavelength of 260 nm in order to increase the transmittance of deep ultraviolet light. Since the larger the band gap is, the more suitably it can be used for a light-emitting device with a shorter wavelength, the band gap is more preferably 4.9 eV or more, and even more preferably 5.0 eV or more. The upper limit of the band gap is not particularly limited, but is usually 10 eV or less. Note that the band gap of each metal oxide uses the value described in "ACS nano, 2012, 6, 5, 4349".

[0023] Examples of the metal oxide nanoparticles having a band gap of 4.8 eV or more include Gd2O3 (5.28 eV), HfO2 (5.41 eV), La2O3 (5.77 eV), Y2O3 (5.85 eV), Yb2O3 (5.1 eV), ZrO2 (5.04 eV), Al2O3 (8.3 eV), and SiO2 (9.1 eV). It is preferably included with at least one kind of nanoparticle selected from the above group. From the viewpoint of enhancing hardness and refractive index, it may be a nanoparticle of a composite oxide composed of two or more kinds.

[0024] From the viewpoint of easy availability, it is more preferable that the metal oxide nanoparticles contain ZrO2 and Al2O3. Since the refractive index of the metal oxide nanoparticles alone is as high as 2.1, it is even more preferable to contain ZrO2.

[0025] The metal oxide nanoparticles may be produced or commercially available products may be used. When producing them, they can be obtained by known methods such as the hydrothermal method, supercritical method, and vapor phase method. Examples of commercially available products of ZrO2 include ZSL-10A, ZSL-10T, ZSL-20N (all manufactured by Daiichi Rare Element Co., Ltd.), Nano Use (registered trademark) ZR-40BL, Nano Use (registered trademark) ZR-30BS, Nano Use (registered trademark) ZR-30AL (all manufactured by Nissan Chemical Industries, Ltd.), Zirconeo-Cw series (manufactured by ITEC Co., Ltd.), and SZR series (manufactured by Sakai Chemical Industry Co., Ltd.). Examples of commercially available products of Al2O3 include alumina sol AS-520-A (manufactured by Nissan Chemical Industries, Ltd.), and the Bilal (registered trademark) Al series such as Al-L7, Al-ML15, and Al-C2 (manufactured by Taki Chemical Co., Ltd.), and the CATALOID series (manufactured by JGC Catalysts & Chemicals Ltd.).

[0026] Since the surface area per volume becomes relatively small, the usage amounts of the silane coupling agent and carboxylic acid described later are reduced, and the dispersibility in the resin is good, the average primary particle size of the metal oxide nanoparticles is preferably 2 nm or more, and more preferably 5 nm or more. On the other hand, since light scattering hardly occurs and the optical properties are excellent, particularly the transmittance of visible light is high, the average primary particle size of the metal oxide nanoparticles is preferably 80 nm or less, and more preferably 50 nm or less. The average primary particle size of the metal oxide nanoparticles is determined by observation with a transmission electron microscope.

[0027] Among metal oxide nanoparticles, there are cases where they are dispersed in a resin in a state where some are secondarily aggregated rather than primary particles. In this case, the average secondary particle diameter of the metal oxide nanoparticles is preferably 10 nm or more, more preferably 30 nm or more. This is because, similar to the average primary particle diameter, the surface area per volume becomes relatively small, reducing the usage amount of the silane coupling agent and carboxylic acid described later and resulting in good dispersibility in the resin. Also, from the viewpoint of preventing light from being scattered and reducing the light extraction efficiency, the average secondary particle diameter is preferably 120 nm or less, more preferably 100 nm or less. Note that the average secondary particle diameter of the metal oxide nanoparticles can be measured by the dynamic light scattering method.

[0028] From the viewpoint of reducing the surface area per volume for the purpose of reducing the usage amount of the silane coupling agent and carboxylic acid, the shape of the metal oxide nanoparticles is preferably close to spherical. Also, in the case of plate-shaped metal oxide nanoparticles, particles with a major axis of 15 nm or more are preferred. When the metal oxide nanoparticles have a shape other than spherical, it is preferable that their volume is equal to or more than the volume of a sphere with an average primary particle diameter of 2 nm, and more preferably equal to or more than the volume of a sphere with an average primary particle diameter of 5 nm.

[0029] From the viewpoint of increasing the d-line refractive index of the resin composition, the content of the metal oxide nanoparticles in the resin composition is preferably 15% by mass or more, more preferably 20% by mass or more. Also, from the viewpoint of preventing the resin composition from aggregating and breaking and enhancing the adhesion between the optical element and the optical member, the content is preferably 70% by mass or less, more preferably 60% by mass or less. The content of the metal oxide nanoparticles in the resin composition is determined by thermogravimetric analysis. By holding the resin composition at, for example, 400°C for a certain period of time and measuring the weight loss, the content of the metal oxide nanoparticles can be determined. That is, the amount of weight loss is the content of the resin, and the weight of the residue is the content of the metal oxide nanoparticles.

[0030] (Resin) The resin constituting the resin composition is not particularly limited as long as it is usually used as the resin interposed between the light-emitting element and the optical member in the light-emitting device. On the other hand, in the ultraviolet light-emitting device, since a light-emitting element that emits light with a shorter wavelength such as ultraviolet light or deep ultraviolet light is used, the energy of the emitted light is large. Therefore, from the viewpoint of preventing the deterioration of the resin due to photodegradation by the light emitted from the light-emitting element, the resin is preferably a resin having high light resistance to ultraviolet light, more preferably at least one of a fluororesin and a silicone-based resin, and even more preferably an amorphous fluororesin or a silicone resin. One type of resin may be used, or two or more types may be mixed and used.

[0031] As the amorphous fluororesin, Cytop (trade name, CYTOP is a registered trademark) manufactured by AGC Inc., Teflon (registered trademark) AF manufactured by Mitsui Chemicals Fluoro Products Co., Ltd., etc. can be used. These amorphous fluororesins are transparent without absorption even in the deep ultraviolet region. Therefore, the loss of light emitted from the light-emitting element can be reduced, and the light extraction efficiency can be improved.

[0032] When, for example, Cytop (trade name) is used as the amorphous fluororesin, the functional groups at the polymer terminals include type A having a COOH group, CONH~Si(OR) n type M having a group, type S having a CF3 group, etc. It is appropriately selected from the viewpoints of the adhesion between the light-emitting element and the optical member and the dispersibility of the metal oxide nanoparticles.

[0033] The glass transition temperature of the amorphous fluororesin is preferably 80°C or higher, more preferably 100°C or higher, from the viewpoint of preventing the deformation of the resin due to the heat generation of the light-emitting element. Also, from the viewpoint of suppressing the decomposition of the resin due to the temperature becoming too high when bonding the light-emitting element and the optical member, it is preferably 260°C or lower, more preferably 250°C or lower.

[0034] A silicone resin refers to a material in which the main backbone of the bond is a siloxane bond where silicon and oxygen are alternately linked, and an organic functional group is linked thereto. As an example of the organic functional group, a functional group having no absorption in the deep ultraviolet region is preferable, and examples thereof include an alkyl group, a vinyl group, a (meth)acryloxy group, and an epoxy group. In the alkyl group, part or all of the hydrogen atoms may be substituted with halogen atoms such as fluorine atoms and chlorine atoms. Also, in this specification, the (meth)acryloxy group is used as a general term including at least one of an acryloxy group and a methacryloxy group.

[0035] As the structure of the main backbone, a linear structure represented by (-R 1 R 2 SiO-) may be used, but silsesquioxane represented by (-R 3 SiO 1.5 -) can be particularly preferably used. In the formula, R 1 ~R 3 means an organic functional group. Silsesquioxane having a structure in which one organic functional group and three oxygen atoms are bonded to a silicon atom has fewer organic functional groups compared to a linear structure, and thus is particularly excellent in light resistance and heat resistance. As the backbone of silsesquioxane, a random structure, a ladder structure, and a cage structure are known, but in one aspect of the present invention, they can be used without particular limitation. Examples of the silsesquioxane resin include the SR series, SP series, and SO series manufactured by KONISHI CHEMICAL CO., LTD.

[0036] (Other components) The resin composition may contain other components in addition to the resin and the metal oxide nanoparticles. Examples of the other components include silane coupling agents, carboxylic acids, amines, amides, and the like. Among them, a silane coupling agent and a carboxylic acid are preferable because they are suitably used for the complexation of the resin and the metal oxide nanoparticles when obtaining the resin composition. The complexation can be carried out by a known method using a silane coupling agent or a carboxylic acid. As the method of complexation using a silane coupling agent, for example, the methods described in Japanese Patent No. 6028733 and Japanese Patent Application Laid-Open No. 2013-177259 can be used. As the method of complexation using a carboxylic acid, for example, the method described in Japanese Patent No. 5375617 can be used.

[0037] The silane coupling agent may be an organosilicon compound having both a hydrophobic organic functional group contributing to the reaction and interaction with an organic substance and a hydrolyzable group (alkoxy group) in one molecule, and a known silane coupling agent can be appropriately used. For example, a silane coupling agent represented by the following formula is preferable. R 1 a Si(OR 2 ) b In the formula, R 1 is an organic functional group, OR 2 represents an alkoxy group having 1 or 2 carbon atoms, a and b are each independently an integer of 1 or more, and the sum (a + b) is 4. When a is 2 or more, a plurality of R 1 may be the same as or different from each other. When b is 2 or more, a plurality of OR 2 may be the same as or different from each other.

[0038] In the above formula, OR 2 is preferably a methoxy group or an ethoxy group. b is preferably 3. R 1 The organic functional group represented by can be appropriately used with a known hydrophobic organic functional group in the silane coupling agent, but a functional group having no absorption in the deep ultraviolet region is preferable. Examples of such organic functional groups include an alkyl group, a vinyl group, a (meth)acryloxy group, an epoxy group, and the like. In addition, in the alkyl group, part or all of the hydrogen atoms may be substituted with a halogen atom such as a fluorine atom or a chlorine atom.

[0039] Examples of the silane coupling agent represented by the above formula include 3,3,3-trifluoropropyltrimethoxysilane, n-octadecyltrimethoxysilane, triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane, vinyltrimethoxysilane, n-propyltrimethoxysilane, n-dodecyltrimethoxysilane, n-decyltrimethoxysilane, n-octyltrimethoxysilane, heptadecatrifluorodecyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and the like. Among them, from the viewpoint of affinity when using an amorphous fluororesin as the resin, a silane coupling agent containing a fluorine atom is preferable, and 3,3,3-trifluoropropyltrimethoxysilane and triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane are more preferable.

[0040] As a component derived from the silane coupling agent, it is preferable to contain at least one of at least a hydrolyzate of the silane coupling agent and a hydrolytic condensate of the silane coupling agent, and it may also contain a silane coupling agent in which a hydrolysis reaction has not occurred.

[0041] The carboxylic acid may be a molecule having one or more carboxyl groups in one molecule. Thereby, the bonding or adsorption to the metal oxide nanoparticles is promoted, and the metal oxide nanoparticles can be more uniformly dispersed in the resin.

[0042] The acidity of the carboxyl group is preferably stronger, the acid dissociation constant represented by pKa is preferably 4 or less, more preferably 3 or less, and even more preferably 2 or less. Examples of the carboxylic acid having a low pKa include organic acids in which one or more hydrogen atoms bonded to the α-position carbon atom of the alkyl group bonded to the carboxyl group are substituted with halogen atoms. Among carboxylic acids substituted with halogen atoms, carboxylic acids substituted with fluorine atoms having a high electronegativity or carboxylic acids having a large number of substituents are preferable because they have a low pKa. Specific examples include perfluoropentanoic acid, perfluorohexanoic acid, tridecafluoroheptanoic acid, and the like. Among them, tridecafluoroheptanoic acid is preferable from the viewpoint of compatibility when an amorphous fluororesin is used as the resin.

[0043] [Optical Element] As shown in FIG. 1, the optical element 10 according to the present embodiment includes an optical member 1 that transmits ultraviolet rays and a resin composition layer 2, and is used in an ultraviolet light emitting device.

[0044] (Resin Composition Layer) The resin composition layer 2 is made of a resin composition, and the resin composition described in the above [Resin Composition] is used. That is, by dispersing metal oxide nanoparticles in the resin, the refractive index of the resin composition can be increased, and a resin composition in which the difference between the d-line refractive index of the resin composition and the d-line refractive index of the resin is 0.03 or more is used. The preferred embodiments of the resin composition are the same as the preferred embodiments described in the above [Resin Composition].

[0045] The resin composition layer 2 is provided on the surface of the optical member 1, that is, on at least one of the light incident surface and the light emitting surface. It is sufficient that the resin composition layer 2 is formed in at least a part of the region of such a surface. For example, as shown in FIG. 2, the resin composition layer 2 may be provided in the entire region (entire surface) on the surface of the optical member 1, or as shown in FIG. 3, in accordance with the size of the semiconductor light emitting element 3 that becomes the other adherend, It may be provided in a part of the region on the surface of the optical member 1. Further, as shown in FIGS. 4 and 10, etc., the resin composition layer 2 may be formed not only on the bonding surface between the optical member 1 and the semiconductor light emitting element 3 but also on the side surface of the semiconductor light emitting element 3. Furthermore, as shown in FIGS. 4 and 7, etc., the resin composition layer 2 may be adhered to the optical member 1 while sealing the semiconductor light emitting element 3. Further, as shown in FIGS. 8 and 12, etc., by using another adhesive layer 5 together with the resin composition layer 2, high light extraction efficiency and adhesive strength may be achieved simultaneously.

[0046] Preferred d-line refractive index n of the resin composition layer d (C)' is the preferred d-line refractive index n of the above resin composition d It is the same as (C). That is, the d-line refractive index n of the resin composition layer d (C)' is preferably 1.39 or more. Since it increases the light extraction efficiency of the semiconductor light-emitting element and raises the output of the ultraviolet light-emitting device, it is preferably 1.4 or more, and more preferably 1.45 or more. Also, the d-line refractive index n d The upper limit of (C)' is not particularly limited, but from the viewpoint of the balance between the adhesion of the optical element and the optical member and the improvement of the output of the ultraviolet light-emitting device, it is usually 1.6 or less. The d-line refractive index n of the resin composition d (C)' can be adjusted by increasing or decreasing the amount of metal oxide nanoparticles. Since the resin composition layer is composed of the resin composition, the d-line refractive index n of the resin composition layer d (C)' and the d-line refractive index n of the resin composition d become the same value.

[0047] The thickness of the resin composition layer is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more from the viewpoint of adhesion. Also, from the viewpoint of suppressing light loss in the resin composition layer, the thickness is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less.

[0048] (Optical member) The optical member 1 has a light incident surface and a light exit surface, and is provided with an optical functional surface in at least a partial region of at least one of the light incident surface and the light exit surface. The light incident surface is, for example, the surface on which the light emitted from the semiconductor light-emitting element is incident, and the light exit surface is the surface on which the incident light passes through the optical member and is emitted to irradiate the outside.

[0049] An optical functional surface refers to a surface that refracts, diffracts, or scatters light, such as a highly reflective surface like a mirror, a low-reflective surface with enhanced transparency, or various filters with wavelength selectivity. The entire surface or only a partial region of the light incident surface or light exit surface of the optical member may have such a function.

[0050] As long as the optical member can exhibit the above functions, various conventionally known optical members can be used. The shape is not particularly limited, and examples include a plate shape, a lens, a lens array, a diffraction grating, a diffractive optical element, and a grating cell array. Further, a metal or a dielectric may be formed on its surface in a single layer or multiple layers. In particular, a spherical, hemispherical, or aspherical convex lens shape is preferable, and a hemispherical shape is more preferable.

[0051] When the optical member is bonded to a light-emitting element such as a semiconductor light-emitting element, since the light exit surface of the light-emitting element is formed of a high refractive index material, the light extraction efficiency can be greatly improved by configuring the optical member with a high refractive index material. Therefore, the d-line refractive index n d (O) of the optical member is preferably 1.45 or more, more preferably 1.5 or more, further preferably 1.6 or more, still further preferably 1.65 or more, and particularly preferably 1.7 or more.

[0052] Δn, which is the absolute value of the difference in the d-line refractive index between the optical member and the resin composition layer d =|n d (O)-n d (C)’| is preferably 0.35 or less, more preferably 0.30 or less, and further preferably 0.28 or less from the viewpoint of preventing reflection at the interface between the optical member and the resin composition layer. Also, the lower limit of Δn d is not particularly limited.

[0053] The light emitted from the light-emitting element passes through the optical member processed into a shape such as a lens and is emitted outside the ultraviolet light-emitting device. Therefore, by using a material with high transmittance at the emission wavelength of the light emitted from the light-emitting element to form the optical member, light loss can be suppressed and the light extraction efficiency can be further improved. The distance that light travels within the optical member is usually about 0.5 to 5 mm, and the absorption coefficient k(O) at the emission wavelength of the light-emitting element of the optical member is 0.2 mm -1 or less is preferable, and 0.15 mm -1 or less is more preferable, and 0.1 mm -1 or less is even more preferable, and 0.07 mm -1 or less is particularly preferable.

[0054] The optical element is preferably used in an ultraviolet light-emitting device including a semiconductor light-emitting element, and the semiconductor light-emitting element preferably has a peak wavelength λ(D) in the wavelength range of 250 to 400 nm. In a semiconductor light-emitting element that emits short-wavelength ultraviolet light, since the light extraction efficiency becomes lower, it is more preferably used in an ultraviolet light-emitting device having a peak wavelength in the wavelength range of 250 to 370 nm, even more preferably 250 to 330 nm, and particularly preferably 250 to 290 nm. The peak wavelength λ(D) is more preferably in the wavelength range of 260 to 285 nm for sterilization applications, more preferably in the wavelength range of 290 to 330 nm for medical applications, and more preferably in the wavelength range of 340 to 380 nm for resin curing applications.

[0055] By installing the optical element so that the resin composition layer is in close contact with the light-emitting surface of the semiconductor light-emitting element, the light extraction efficiency of the semiconductor light-emitting element can be increased. When the optical element is used in an ultraviolet light-emitting device including a semiconductor light-emitting element, it is preferable to provide a resin composition layer at least on the light incident surface of the optical element.

[0056] The refractive index n o (O) of the optical member at the peak wavelength λ(D) of the semiconductor light-emitting element and the refractive index n o (C)' of the resin composition layer, and the absolute value of the difference Δn o =|n o (O) - n o (C)'| is preferably 0.42 or less, more preferably 0.40 or less, even more preferably 0.35 or less, and particularly preferably 0.30 or less from the viewpoint of preventing reflection at the interface between the optical member and the resin composition layer. Also, the lower limit of Δn o is not particularly limited.

[0057] It is preferable that the optical member has a high glass transition temperature Tg(O) so that the shape of the optical member does not deform even when heated during a production process such as an adhesion process between a light-emitting element and the optical member. Tg(O) is preferably 350 °C or higher, more preferably 400 °C or higher, and even more preferably 500 °C or higher.

[0058] The material constituting the optical member is not particularly limited, and inorganic glass, quartz (Tg: 1060 °C, Tc: 1210 °C, n d : 1.46), sapphire which is a crystal (n d (ordinary light): 1.77, melting point: 2053 °C), and transparent ceramic materials such as spinel and aluminum oxynitride can be used.

[0059] If the durability is high, and there is no risk of deterioration even when the optical member is exposed to high-power light emitted by the semiconductor light-emitting element, particularly short-wavelength light such as ultraviolet light, for a long time, and it also has excellent heat resistance, the product life as an optical member can be extended. From this perspective, it is preferable to use an inorganic material, specifically inorganic glass, quartz, sapphire, or spinel, for the optical member.

[0060] Furthermore, inorganic glass can be easily processed into various shapes and is particularly preferably used from the viewpoints of reducing manufacturing costs and mass production. In order to suppress the light loss during light transmission through the optical member, the inorganic glass is more preferably an ultraviolet highly transmissive glass having a maximum absorption coefficient αmax in the wavelength range of 260 to 400 nm of 0.2 mm -1 or less, and it is even more preferably 0.15 mm -1 or less in the maximum absorption coefficient αmax in such a wavelength range, 0.1 mm -1 or less is even more preferable, and 0.07 mm -1 or less is particularly preferable. The smaller the maximum absorption coefficient αmax, the more preferable.

[0061] When using inorganic glass as the optical member, for example, borosilicate glass, silicate glass, phosphate glass, and fluorophosphate glass can be mentioned.

[0062] Borosilicate glass is a glass that contains SiO2 and B2O3 as main components, and includes Al2O3, alkaline earth metal oxides (MgO, CaO, SrO, BaO), alkali metal oxides (Li2O, Na2O, K2O), and other metal oxides. Silicate glass is a glass that contains SiO2 as the main component and includes B2O3, Al2O3, alkaline earth metal oxides (MgO, CaO, SrO, BaO), alkali metal oxides (Li2O, Na2O, K2O), and other metal oxides. Phosphate glass is a glass that contains P2O5 as the main component and includes Al2O3, alkaline earth metal oxides (MgO, CaO, SrO, BaO), alkali metal oxides (Li2O, Na2O, K2O), and other metal oxides. Metaphosphate glass is a glass that contains P2O5 as the main component and includes fluorides of Al, alkaline earth metals (Mg, Ca, Sr, Ba), alkali metals (Li, Na, K), and other metals, as well as other metal oxides. In this specification, the main component of glass refers to the network-forming oxide that forms the skeleton of the glass among the components constituting the glass.

[0063] It is preferable that the optical member has a high glass transition temperature Tg so that the shape of the optical member does not deform even when heated during a production process such as an adhesion process between a semiconductor light-emitting element and the optical member. Tg is preferably 350 °C or higher, more preferably 400 °C or higher, and even more preferably 500 °C or higher. The upper limit of Tg is not particularly limited, but is usually 1000 °C or lower.

[0064] For such glass, when the content of the iron component is high, the ultraviolet transmittance decreases. Therefore, the glass constituting the optical member preferably has a particularly reduced content of the iron component. Here, the iron component is Fe 3+ or Fe 2+ and exists in the glass with such valence, and the total iron oxide content obtained by converting the iron component contained in the glass to Fe2O3 is represented as T-Fe2O3. T-Fe2O3 in the glass is preferably 10 mass ppm or less, more preferably 5 mass ppm or less, still more preferably 2.5 mass ppm or less, even more preferably 2 mass ppm or less, particularly preferably 1 mass ppm or less, and the lower the content, the more preferable. The above iron component is introduced into the glass mainly as an impurity contained in the glass raw material, except for the iron content mixed in from the melting process.

[0065] In particular, when the semiconductor light-emitting element emits ultraviolet light in the wavelength range of 250 nm to 400 nm, T-Fe2O3 in the inorganic glass with high transmittance in the ultraviolet region is preferably 5 mass ppm or less, more preferably 2 mass ppm or less, still more preferably 1.5 mass ppm or less, even more preferably 1 mass ppm or less, particularly preferably less than 0.9 mass ppm, and the lower the content, the more preferable.

[0066] Also, from the viewpoints of enhancing the durability of the optical member and reducing the absorption coefficient in the ultraviolet region, it is also preferable that the optical member is composed of quartz, sapphire, or spinel. Quartz is a glass of high-purity SiO2, with a d-line refractive index of 1.46 and a refractive index at 275 nm of about 1.5. Sapphire is a single crystal of α-alumina (α-Al2O3), with a d-line refractive index of 1.77 and a refractive index at 275 nm of about 1.83. Spinel is a crystal of the MgO·Al2O3 system (MgAl2O4).

[0067] An antireflection film can also be formed on the surface of the optical member. For example, a single-layer film or a multilayer film of a dielectric such as SiO2, MgF2, Al2O3, HfO2, ZrO2, Ta2O5, etc. is used. By forming the antireflection film, Fresnel reflection on the surface of the optical member is reduced, so that the light extraction efficiency can be further improved.

[0068] [Ultraviolet Light Emitting Device] The ultraviolet light-emitting device 20 according to the present embodiment has, for example, as shown in FIG. 2, a substrate 4, a semiconductor light-emitting element 3 provided on the substrate 4, and an optical element 10 provided on the semiconductor light-emitting element 3. The optical element 10 has a resin composition layer 2 formed on at least a partial region of the surface of the optical member 1, and the optical element 10 is provided on the light-emitting surface of the semiconductor light-emitting element 3 via the resin composition layer 2. By providing the semiconductor light-emitting element 3 and the optical member 1 via the resin composition layer 2, no space, that is, no air layer, intervenes between the semiconductor light-emitting element 3 and the optical member 1. Therefore, total reflection occurring at the light-emitting surface and the air interface can be prevented, and high light extraction efficiency can be realized.

[0069] As the optical element in the ultraviolet light-emitting device, the same one as described in the above [Optical Element] can be used. That is, in the resin composition layer constituting the optical element, metal oxide nanoparticles are dispersed in the resin, and a resin composition characterized by a high refractive index in which the difference between the d-line refractive index of the resin composition and the d-line refractive index of the resin is 0.03 or more is used. The preferred embodiment of the resin composition is the same as the preferred embodiment described in the above [Resin Composition]. As the optical member constituting the optical element, the one described in the above (Optical Member) can be used, and the preferred embodiment is also the same.

[0070] As the semiconductor light-emitting element in the ultraviolet light-emitting device, a commonly used one can be used, but it preferably has a peak wavelength λ(D) in the wavelength range of 250 to 400 nm. In a semiconductor light-emitting element that emits short-wavelength ultraviolet light, since the light extraction efficiency becomes lower, it is more preferably used in an ultraviolet light-emitting device having a peak wavelength in the wavelength range of 250 to 370 nm, still more preferably 250 to 330 nm, and particularly preferably 250 to 290 nm. As described above, the peak wavelength λ(D) has a different more preferred wavelength range depending on the application. Specifically, in the case of a sterilization application, it is more preferable that the peak wavelength λ(D) is in the wavelength range of 260 to 285 nm. In the case of a medical application, it is more preferable that the peak wavelength λ(D) is in the wavelength range of 290 to 330 nm. In the case of a resin curing application, it is more preferable that the peak wavelength λ(D) is in the wavelength range of 340 to 380 nm.

[0071] In an ultraviolet light emitting device, the light emitting surface of a semiconductor light emitting element and an optical member are brought into close contact with each other through a resin composition layer. When the semiconductor light emitting element and the optical member are adhered only with the resin composition layer without using another adhesive layer, the adhesive strength between the light emitting surface of the semiconductor light emitting element and the optical member by the resin composition layer is preferably 5 N / mm 2 or more in shear strength, more preferably 7 N / mm 2 or more, and even more preferably 10 N / mm 2 or more. The upper limit of the shear strength is not particularly limited, but is usually 20 N / mm 2 or less. Note that the shear strength is a value measured in accordance with MIL STD 883 and can be measured using a bond tester DAGE 4000plus manufactured by Nordson Corporation. Further, the shear strength can be adjusted, for example, by the number of organic functional groups contained in the adhesive layer, for example, the resin composition layer.

[0072] As the semiconductor light emitting element, either a vertical structure in which a semiconductor layer is formed on an LED substrate and electrodes are provided on the back surface of the LED substrate and the surface of the semiconductor layer, or a flip chip structure in which both a p electrode and an n electrode are provided on the surface of the semiconductor layer can be adopted. The light emitting surface of the semiconductor light emitting element is often an AlGaN-based semiconductor layer or a transparent electrode in the case of the vertical structure, and sapphire or aluminum nitride in the case of the flip chip structure.

[0073] As described above, the ultraviolet light emitting device 20 according to the present embodiment includes a substrate 4, a semiconductor light emitting element 3 provided on the substrate 4, and an optical element 10 provided on the semiconductor light emitting element 3. In the ultraviolet light emitting device 20 of FIG. 2, the resin composition layer 2 is formed over the entire surface of the optical member 1, and the entire surface on the light emitting surface of the semiconductor light emitting element 3 is adhered to the optical member 1 through the resin composition layer 2. With such a configuration, when forming the resin composition layer 2, it is only necessary to apply and form the resin composition over the entire adhesion surface of the optical member 1, and the formation of the resin composition layer 2 becomes easy.

[0074] Regarding such a configuration, FIGS. 3 to 16 are shown as modified examples of the ultraviolet light emitting device 20, but the configuration of the ultraviolet light emitting device according to the present embodiment is not limited thereto.

[0075] In the ultraviolet light emitting device 20 of FIG. 3, a resin composition layer 2 is formed in a partial region on the surface of the optical member 1, and the entire surface on the light emitting surface of the semiconductor light emitting element 3 is adhered to the optical member 1 via the resin composition layer 2. With such a configuration, when forming the resin composition layer 2, the resin composition may be applied and formed on the entire adhesion surface of the semiconductor light emitting element 3, and the formation of the resin composition layer 2 becomes easy.

[0076] In the ultraviolet light emitting device 20 of FIG. 4, a resin composition layer 2 is formed in a partial region on the surface of the optical member 1, and the resin composition layer 2 is provided and sealed not only on the entire surface on the light emitting surface of the semiconductor light emitting element 3 but also on the entire side surface region. In the ultraviolet light emitting device 20 of FIG. 5, a resin composition layer 2 is formed in the entire region on the surface of the optical member 1, and the resin composition layer 2 is provided and sealed not only on the entire surface on the light emitting surface of the semiconductor light emitting element 3 but also on the entire side surface region. A resin composition layer 2 is provided without a gap between the substrate 4 and the optical member 1. By sealing the semiconductor light emitting element 3 with the resin composition layer 2, the intrusion of substances that accelerate the deterioration of the semiconductor light emitting element 3, such as moisture in the atmosphere, from the outside world can be prevented, and as a result, the performance deterioration of the semiconductor light emitting element 3 can be suppressed.

[0077] In the ultraviolet light emitting device 20 of FIG. 6, the outer peripheral portion of the optical member 1 is extended to contact the substrate 4. The entire surface on the light emitting surface of the semiconductor light emitting element 3 is adhered to the optical member 1 via the resin composition layer 2. In the ultraviolet light emitting device 20 of FIG. 7, the outer peripheral portion of the optical member 1 is extended to contact the substrate 4. The semiconductor light emitting element 3 is sealed with the resin composition layer 2 and adhered to the optical member 1 via the resin composition layer 2. Since a part of the optical member 1 is in contact with or adhered to the substrate 4, the optical member 1 is less likely to fall off from the semiconductor light-emitting element 3. The optical member 1 and the substrate 4 may be brought into contact with each other by extending the outer peripheral portion of the optical member 1 as shown in FIGS. 6 and 7, or may be brought into contact with each other on other surfaces. As shown in FIG. 8 and the like, they may be brought into contact with each other via an adhesive layer 5 or the like.

[0078] In the ultraviolet light-emitting device 20 of FIG. 8, the optical element 10 is adhered to the substrate 4 via the adhesive layer 5. The adhesive layer 5 may be a single material, or may be composed of a plurality of adhesives or members. The optical element 10 is provided on the semiconductor light-emitting element 3 via the resin composition layer 2. Since the optical element 10 is adhered to the substrate 4 by the adhesive layer 5, even if the resin composition layer 2 is a non-adhesive material, the optical element 10 is less likely to fall off. As the adhesive layer 5, a conventionally known one can be used. For example, it can be formed of an inorganic adhesive such as a metal solder or a low-melting glass. When the adhesive layer 5 is provided at a position where the light emitted from the semiconductor light-emitting element 3 does not strongly hit, it may be formed of an organic adhesive such as a silicone-based one. Also, ceramic materials and glass can be used.

[0079] In the ultraviolet light-emitting device 20 of FIG. 9, the outer peripheral portion of the optical member 1 is extended and fixed to the substrate 4 via the adhesive layer 5. Instead of extending the outer peripheral portion of the optical member 1, a similar shape may be obtained by adhering another member to the outer peripheral portion of the optical member 1. On the other hand, the semiconductor light-emitting element 3 is sealed with the resin composition layer 2 and is in close contact with the optical member 1 via the resin composition layer 2. Since the adhesive strength is increased by using the adhesive layer 5, it is also possible to design the resin composition layer 2 with priority given to improving the light extraction efficiency over adhesiveness. In the ultraviolet light-emitting device 20 of FIG. 10, a concave portion is provided in a part of the substrate surface, the outer peripheral portion of the optical member 1 is extended toward the concave portion, and is fixed to the substrate 4 via the adhesive layer 5. Instead of extending the outer peripheral portion of the optical member 1, a similar shape may be obtained by adhering another member to the outer peripheral portion of the optical member 1. The entire surface on the light-emitting surface of the semiconductor light-emitting element 3 is in close contact with the optical member 1 via the resin composition layer 2. By extending the outer peripheral portion of the optical member 1 and fixing it to the substrate 4 via the adhesive layer 5, the adhesion between the optical member 1 and the semiconductor light-emitting element 3 can be made stronger, and the intrusion of moisture and the like from the outside can be prevented. As a result, the performance degradation of the semiconductor light-emitting element 3 can be suppressed. In addition, the amount of light emitted from the semiconductor light-emitting element 3 hitting the adhesive layer 5 can be suppressed. As the adhesive layer 5, a conventionally known one can be used. For example, it can be formed of an inorganic adhesive such as metal solder or low melting point glass. When the adhesive layer 5 is provided at a position where the light emitted from the semiconductor light-emitting element 3 does not strongly hit, it may be formed of an organic adhesive such as a silicone-based one.

[0080] In the ultraviolet light-emitting device 20 of FIG. 11, a resin composition layer 2 is formed in a partial region on the surface of the optical member 1, and not only the entire surface on the light-emitting surface of the semiconductor light-emitting element 3 but also at least a part of the side surface is covered with the resin composition layer 2. Further, the outer peripheral portion of the optical member 1 is extended to cover a part of the side surface of the semiconductor light-emitting element 3 together with the resin composition layer 2. Instead of extending the outer peripheral portion of the optical member 1, a similar shape may be obtained by adhering another member to the outer peripheral portion of the optical member 1. The resin composition layer 2 may cover the entire side surface of the semiconductor light-emitting element 3, for example, as shown in FIG. 4. By covering at least a part of the side surface of the semiconductor light-emitting element 3, high light extraction efficiency can also be obtained for the light emitted from this side surface.

[0081] In the ultraviolet light-emitting device 20 of FIG. 12, the outer peripheral portion of the substrate 4 is extended and fixed to the optical member 1 via the adhesive layer 5. Instead of extending the outer peripheral portion of the substrate 4, a similar shape may be obtained by adhering another member to the outer peripheral portion of the substrate 4. On the other hand, the entire surface on the light-emitting surface of the semiconductor light-emitting element 3 is in close contact with the optical member 1 via the resin composition layer 2. The ultraviolet light emitting device 20 in Fig. 13 extends the outer peripheral portion of the optical member 1 and fixes it to the substrate 4 via the adhesive layer 5. Instead of extending the outer peripheral portion of the optical member 1, a similar shape may be obtained by adhering another member to the outer peripheral portion of the optical member 1. On the other hand, by raising the inside of the portion of the substrate 4 in contact with the optical member 1 to provide a convex portion, the substrate 4 is also fixed to the side surface of the adhesive layer 5. The entire surface on the light emitting surface of the semiconductor light emitting element 3 is in close contact with the optical member 1 via the resin composition layer 2. The ultraviolet light emitting device 20 in Fig. 14 extends the outer peripheral portion of the base material 4 to form a stepped shape, and an adhesive layer 5 is provided there, and is fixed to the outer peripheral portion of the optical member 1 and a partial region of the spherical surface. The entire surface on the light emitting surface of the semiconductor light emitting element 3 is in close contact with the optical member 1 via the resin composition layer 2. The effect of the adhesive layer 5 is the same as the effect of the adhesive layer 5 in Fig. 8 and the like. Also, instead of adhering on only one surface, stronger adhesion can be achieved by adhering on a plurality of surfaces as shown in Fig. 13 and Fig. 14.

[0082] The ultraviolet light emitting device 20 in Fig. 15 has the substrate 4 in the shape of a container with side walls and is covered with a cover 6. The resin composition layer 2 is formed over the entire surface area of the optical member 1, and the entire surface on the light emitting surface of the semiconductor light emitting element 3 is adhered to the optical member 1 via the resin composition layer 2. The ultraviolet light emitting device 20 in Fig. 16 has the cover 6 in the shape of a lid with side walls and is provided on the substrate 4. The resin composition layer 2 is formed in a partial region of the surface of the optical member 1, and the entire surface on the light emitting surface of the semiconductor light emitting element 3 is adhered to the optical member 1 via the resin composition layer 2. The cover 6 may be formed of a material that transmits the light emitted from the semiconductor light emitting element 3, and a material with high transmittance at the wavelength of the emitted light is preferable. Examples of such materials include quartz and inorganic glass. The cover 6 and the substrate 4 can be adhered with a metal solder, an inorganic adhesive, an organic adhesive, etc., thereby preventing the intrusion of moisture and the like from the outside and suppressing the performance deterioration of the semiconductor light emitting element 3. In addition, when the cover 6 is box-shaped as shown in Fig. 16, the substrate 4 may be flat, which can suppress costs. Furthermore, since the side surface is composed of the cover 6, the light radiated from the semiconductor light-emitting element 3 in the side direction can also be extracted to the outside, so the extraction efficiency can be further improved.

[0083] The ultraviolet light-emitting device attaches the semiconductor light-emitting element 3 onto the substrate 4 by a known method such as die bonding, and separately prepares the optical member 1 by processing, forming, etc. Next, a resin composition for forming the resin composition layer 2 is prepared. The resin composition is applied to the bonding surface of the optical member 1 by a known method such as spin coating, dip coating, or potting to form the resin composition layer 2, thereby preparing the optical element 10. At this time, depending on the resin composition, heating may be performed to remove the solvent. The optical element 10 is arranged such that the resin composition layer 2 contacts the light-emitting surface of the semiconductor light-emitting element 3, and heated to a temperature at which the resin composition softens, for example, 100°C to 270°C. A load can also be applied to the optical element 10 so that the softened resin composition layer 2 fills the gap between the optical member 1 and the semiconductor light-emitting element 3. Then, by cooling and curing, the resin composition layer 2 causes the optical member 1 and the semiconductor light-emitting element 3 to adhere closely, obtaining the ultraviolet light-emitting device 20. It is also possible to produce the ultraviolet light-emitting device 20 in the order of first providing the optical element 10 on the semiconductor light-emitting element 3 and then attaching it to the substrate 4. Also, when using a thermosetting resin, a photocurable resin, or the like as the resin composition, the resin composition is applied to at least one bonding surface of the optical member 1 and the semiconductor light-emitting element 3, and after bonding them together, heat or light is irradiated to cure it. Thus, the resin composition layer 2 causes the optical member 1 and the semiconductor light-emitting element 3 to adhere closely, obtaining the ultraviolet light-emitting device 20. It is also possible to produce the ultraviolet light-emitting device 20 by first providing the optical element 10 on the semiconductor light-emitting element 3 and then attaching it to the substrate 4.

Example

[0084] Examples are given below to specifically explain the present invention, but the present invention is not limited thereto.

[0085] [Example 1-1: Resin Composition 1] 2 g of amorphous fluororesin (CYTOP CTL-109AE, manufactured by AGC, solid content concentration 9 wt%) was weighed into a 20 mL vial and diluted with 1 mL of fluorosolvent (CYTOP CT-SOLV100E, manufactured by AGC). Then 100 mg of tridecafluoroheptanoic acid was added and stirred until homogeneous. The resulting fluororesin solution was transparent. 0.75 mL of ZrO₂ nanoparticles (ZSL-20N, manufactured by Daiichi Rare Metals Co., Ltd., solid content concentration 20 wt%, average secondary particle diameter 60 - 105 nm, band gap 5.04 eV) was weighed into another vial and diluted with 3 mL of pure water. The resulting liquid, which was an aqueous layer containing metal oxide nanoparticles, was slightly turbid. The aqueous layer containing metal oxide nanoparticles was gently added to the fluororesin solution, and using a rotation-revolution mixer (Thinky ARE-310), it was stirred and then defoamed. After this operation, the ZrO₂ nanoparticles contained in the aqueous layer transferred to the fluororesin solution, and the upper aqueous layer became transparent while the lower layer became a slightly turbid fluororesin solution. By removing the upper layer, a resin composition solution in which ZrO₂ nanoparticles were dispersed in the fluororesin solution was obtained. This resin composition solution was dried at 50 °C for 5 minutes and then at 100 °C for 30 minutes to obtain Resin Composition 1.

[0086] [Example 1-2: Resin Composition 2] A resin composition 2 in which ZrO₂ nanoparticles were dispersed in the fluororesin was obtained in the same manner as in Example 1, except that the amount of tridecafluoroheptanoic acid was 40 mg and the amount of ZrO₂ nanoparticles was 0.2 mL.

[0087] [Example 1-3: Resin Composition 3] A resin composition 3 in which ZrO₂ nanoparticles were dispersed in the fluororesin was obtained in the same manner as in Example 1, except that the amount of tridecafluoroheptanoic acid was 300 mg and the amount of ZrO₂ nanoparticles was 2.2 mL.

[0088] [Example 1-4: Resin Composition 4] The resin composition 4 was prepared using amorphous fluororesin (CYTOP CTX-809SP2, manufactured by AGC, solid content concentration 9 wt%) as it was.

[0089] [Example 1-5: Resin Composition 5] The resin composition 5 was prepared by directly using an amorphous fluororesin (Cytop CTL-109AE, manufactured by AGC Inc., solid content concentration: 9% by weight).

[0090] [Example 1-6: Resin Composition 6] 0.75 g of an amorphous silicone resin (silsesquioxane, SR-13H, solid content concentration: 94.4% by weight) was weighed into a 20 mL vial. Next, 1.1 g of ZrO2 nanoparticles (SZR-KM, manufactured by Sakai Chemical Industry Co., Ltd., zirconia concentration: 30.5% by weight, dispersant concentration: 3.1% by weight, particle size distribution D50 determined by dynamic light scattering method: 7 nm, band gap: 5.04 eV) was added. This solution was stirred using a rotation-revolution mixer (Avatoki Ryorotaro ARE-310, manufactured by Thinky Corporation) to obtain a resin composition solution in which the ZrO2 nanoparticles were dispersed in the silicone resin. This resin composition solution was dried at 50 °C for 5 minutes and then at 100 °C for 30 minutes to obtain the resin composition 6.

[0091] [Example 1-7: Resin Composition 7] A resin composition 7 in which ZrO2 nanoparticles were dispersed in a silicone resin was obtained in the same manner as in Example 1-6, except that 0.5 g of an amorphous silicone resin was weighed and 1.6 g of ZrO2 nanoparticles was added.

[0092] [Example 1-8: Resin Composition 8] The resin composition 8 was prepared by directly using an amorphous silicone resin (SR-13H, solid content concentration: 94.4% by weight).

[0093] The resin compositions of Example 1-1 to Example 1-3, Example 1-6, and Example 1-7 are examples, and the resin compositions of Example 1-4, Example 1-5, and Example 1-8 are comparative examples in which metal oxide nanoparticles are not dispersed. Their compositions are summarized in the following table. Note that the dispersant in Table 2 is the dispersant originally contained in the used ZrO2 nanoparticles and is not an additional one.

[0094]

Table 1

[0095]

Table 2

[0096] [Evaluation] (Refractive index measurement) The resin composition solution was dropped onto quartz glass and coated with a bar coater having a gap of 150 μm. Then, it was dried at 50°C for 5 minutes and then at 100°C for 30 minutes to form a resin composition layer with a film thickness of 6 μm, which was used as a refractive index measurement sample. The refractive index of the refractive index measurement sample was measured using a prism coupler (manufactured by Metricon: Model 2010). The measurement temperature was 30°C, and the wavelengths were 452 nm, 532 nm, and 632 nm. From the refractive indices at these three wavelengths, the refractive index for light of a specific wavelength was calculated using the Cauchy dispersion formula represented by the following equation. n(λ)=A+(B / λ 2 )+(C / λ 4 ) In the formula, λ represents the wavelength of light, and n(λ) represents the refractive index for light of wavelength λ. A, B, and C are constants determined experimentally. Table 3 shows the measured values of the refractive indices at wavelengths 452 nm, 532 nm, and 632 nm, and the refractive indices at wavelengths 265 nm, 275 nm, 285 nm, and 587.6 nm (d line) calculated using the Cauchy dispersion formula. Note that the resin compositions of Examples 1-4 and 1-5 are composed only of resin, and such resin is the same as the resin in the resin compositions of Examples 1-1 to 1-3. Therefore, the d-line refractive index n d (R) of the resin in the resin compositions of Examples 1-1 to 1-3 is the same value as the d-line refractive index n d (C)=1.34 of the resin compositions of Examples 1-4 and 1-5. Similarly, the resin composition of Example 1-8 is composed only of resin, and such resin is the same as the resin in the resin compositions of Examples 1-6 and 1-7. Therefore, the d-line refractive index n d(R) is the d-line refractive index n of the resin compositions of Examples 1-8 d (C) becomes the same value as 1.42.

[0097] (Average transmittance) The resin composition solution was dropped onto quartz glass and coated with a bar coater having a gap of 150 μm. Then, it was dried at 50 °C for 5 minutes and then at 100 °C for 30 minutes to form a resin composition layer with a film thickness of 6 μm, which was used as a measurement sample for transmittance measurement. Using a spectrophotometer (Ocean Insight, model: HR2000), the external transmittance in the wavelength range of 260 to 400 nm was measured, and the average value was obtained. The results are shown in Table 3.

[0098]

Table 3

[0099] [Examples 3-1 to 3-20: Optical Element] As the optical member, raw materials such as corresponding nitrates, sulfates, hydroxides, oxides, boric acid, etc. were weighed so as to have the compositions of Examples 2-1 to 2-4 described in Table 4, and after thoroughly mixing, they were put into a platinum crucible and heated and dissolved in the temperature range of 1150 °C to 1350 °C for 1.5 hours to 3 hours. This molten glass was dropped from a pipe attached to a glass melting furnace and cooled and solidified to obtain a glass rough ball in a rough spherical shape. Next, the surface of the glass rough ball was polished to produce a glass polished ball. In addition to the above method, a glass block can also be produced by machining a glass plate obtained by forming and solidifying it into a plate shape with a blade or the like, and reheating and deforming it, and then polishing the surface with a ball polishing machine to obtain a glass polished ball. The obtained glass polished ball was processed into a hemispherical shape by slicing or polishing to produce a hemispherical lens (optical member). The blanks in the compositions in Table 4 mean that the content of such components is less than the detection limit value.

[0100] The resin composition solution prepared by the same method as described above was applied by potting using a micropipette to the flat surface portion of the obtained hemispherical lens, which is an optical member, and dried at 50 °C for 5 minutes and then at 100 °C for 30 minutes to form a resin composition layer. The thickness of the resin composition layer was 10 μm. Each of the optical elements of Examples 3-1 to 3-4 was obtained by forming the resin composition layer of the resin composition of Example 1-1 on the flat surface portion of the hemispherical lens made of the glass of Examples 2-1 to 2-4. By the same method, each of the optical elements of Examples 3-5 to 3-8 was obtained from the resin composition of Example 1-2 and the glass of Examples 2-1 to 2-4. By the same method, each of the optical elements of Examples 3-9 to 3-12 was obtained from the resin composition of Example 1-3 and the glass of Examples 2-1 to 2-4. By the same method, each of the optical elements of Examples 3-13 to 3-16 was obtained from the resin composition of Example 1-6 and the glass of Examples 2-1 to 2-4. By the same method, each of the optical elements of Examples 3-17 to 3-20 was obtained from the resin composition of Example 1-7 and the glass of Examples 2-1 to 2-4. Examples 3-1 to 3-20 are all examples.

[0101] [Evaluation] [Refractive Index Measurement] The refractive index of the optical member was measured using a precision refractometer (manufactured by Shimadzu Corporation, model: KPR-200, KPR-2000) with a sample obtained by processing a glass block prepared by the same method as described above into a rectangular parallelepiped shape with a side length of 5 mm or more and a thickness of 5 mm or more. Table 4 shows the measured values at 587.6 nm (d-line) and the refractive indices at wavelengths of 265 nm, 275 nm, and 285 nm calculated by the Cauchy dispersion formula. Also, for the optical element, with respect to the d-line (wavelength 587.6 nm), the refractive index n d (O) of the optical member and the refractive index n d (C)' of the resin composition layer, and the absolute value Δn d =|n d (O)-n d (C)'| are shown in Table 5 and Table 6. Note that the refractive index n d (C)' of the resin composition layer is the same value as the refractive index n d (C) of the resin composition.

[0102] [Absorption Coefficient] For the optical member, the absorption coefficient was calculated by measuring the external transmittance using a spectrophotometer (manufactured by Hitachi High-Technologies Corporation, model: U-4100) for samples of glass blocks polished on both sides to have thicknesses of 10 mm, 5 mm, and 1 mm. The external transmittance and the absorption coefficient have the following relationship. T is the external transmittance, α is the absorption coefficient, d is the thickness of the sample, and r is the single-sided reflectance. lnT = -α×d + ln(1 - r) 2 Table 4 shows the absorption coefficients at each wavelength and the maximum value αmax of the absorption coefficient in the wavelength range of 260 to 400 nm.

[0103] (Fe content) The total iron oxide content (T-Fe2O3) of the optical member was measured by ICP mass spectrometry according to the following procedure. Hydrofluoric acid and sulfuric acid mixed acid were added to the pulverized glass block and heated for decomposition. After decomposition, hydrochloric acid was added to make a certain volume, and the concentration of Fe was measured by ICP mass spectrometry. The concentration was calculated by a calibration curve prepared using a standard solution. From this measured concentration and the decomposition amount of the glass, T-Fe2O3 in the glass was calculated. The ICP mass spectrometer used was Agilent 8800 manufactured by Agilent Technologies. The results are shown in Table 4.

[0104] (Glass transition temperature) The glass transition temperature Tg of the optical member was measured using a thermomechanical analyzer (manufactured by Rigaku Corporation, model: Thermo Plus TMA8310) for samples of glass blocks processed into cylindrical shapes with a diameter of 5 mm and a length of 20 mm at a heating rate of 5 °C / min. The results are shown in Table 4.

[0105] [Table 4]

[0106] [Table 5]

[0107] [Table 6]

[0108] [Examples 4-1 to 4-17: Ultraviolet Light Emitting Device] On a substrate made of aluminum nitride with metal wiring, a semiconductor light emitting element with a peak wavelength λ(D) of 275 nm and a flip-chip structure, and a sapphire substrate with a mirror-like light emitting surface, was provided. Optical elements in which a resin composition layer of each of the resin compositions of Examples 1-1 to 1-8 was formed on the flat surface portion of a hemispherical optical member made of Example 2-4 or quartz were respectively prepared, and the optical elements were arranged so that the resin composition layer was in contact with the light emitting surface of the semiconductor light emitting element. Then, it was left standing on a hot plate and heated at 260 °C for 10 minutes, and then cooled, whereby an optical element was provided to the semiconductor light emitting element via the resin composition layer, and an ultraviolet light emitting device was obtained. In addition, even in the case of a semiconductor light emitting element having a light emitting surface made of aluminum nitride substrate, an optical element can be provided by the same process.

[0109] Regarding the effect of improving the light extraction efficiency obtained by the above-described ultraviolet light emitting device, verification was performed by calculating the output of the emitted light emitted from the semiconductor light emitting element to the outside of the light emitting element by optical simulation. In the optical simulation, the output of the emitted light emitted to the outside of the light emitting element is calculated by the ray tracing method. Table 7 shows the calculation model of the semiconductor light emitting element used in the calculation, and Tables 8 and 9 show the resin composition layer and the optical member used in each study example. The semiconductor light emitting element is composed, in order from the substrate side, of a contact layer, a light emitting layer, and a sapphire substrate. The contact layer is p-GaN, a perfect absorber that absorbs ultraviolet light, and the light emitting layer is an AlGaN-based semiconductor material having a refractive index of about 2.5.

[0110] The light generated in the light-emitting layer passes through the sapphire substrate and is emitted from the light-emitting surface on the upper surface side of the sapphire substrate to the outside of the semiconductor light-emitting element. The output of the emitted light counts the light emitted above the light-emitting surface of the semiconductor light-emitting element. Here, Example 4-1 is an ultraviolet light-emitting device of a semiconductor light-emitting element without an optical element, which is a comparative example without using an optical element. Examples 4-5, 4-6, 4-10, and 4-11 are comparative examples using Resin of Example 1-4 or Example 1-5 in which metal oxide nanoparticles are not dispersed in the resin composition layer of the optical element. Examples 4-16 and 4-17 are comparative examples using Resin of Example 1-8 in which metal oxide nanoparticles are not dispersed in the resin composition layer of the optical element.

[0111] Regarding the output of the emitted light of the ultraviolet light-emitting device of each study example shown in Table 8 and Table 9, the ratio to the output of the emitted light of Example 4-1 is defined as the Enhancement Factor. That is, the Enhancement Factor is a value representing how many times the light output of the ultraviolet light-emitting device has increased by attaching an optical element to the semiconductor light-emitting element. The results of optical simulations using a semiconductor light-emitting element with a peak wavelength λ(D) = 275 nm are shown in Table 8 and Table 9.

[0112]

Table 7

[0113]

Table 8

[0114]

Table 9

[0115] The Enhancement Factors of Examples 4-2 to 4-17 all exceed 1.0, indicating that the light extraction efficiency can be improved by providing an optical element on a semiconductor light-emitting element. Furthermore, the Enhancement Factors of Examples 4-2 to 4-4 are larger than those of Examples 4-5 and 4-6. From this, it can be seen that by using a resin composition in which metal oxide nanoparticles are dispersed to have a higher refractive index than the resin for the resin composition layer of the optical element, the light extraction efficiency can be further improved. Similarly, the Enhancement Factors of Examples 4-7 to 4-9 are larger than those of Examples 4-10 and 4-11, indicating that the light extraction efficiency can be further improved by using an optical element provided with a resin composition layer having a higher refractive index. Also, the Enhancement Factors of Examples 4-12 and 4-13 are larger than that of Example 4-16, and the Enhancement Factors of Examples 4-14 and 4-15 are larger than that of Example 4-17, indicating that the light extraction efficiency can be further improved by using an optical element provided with a resin composition layer having a higher refractive index.

[0116] From the above results, it was shown that by providing an optical element on a semiconductor light-emitting element through a resin composition layer in which metal oxide nanoparticles are dispersed in a resin to increase the refractive index, the light extraction efficiency can be improved more than before.

[0117] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention. This application is based on a Japanese patent application filed on May 29, 2020 (Japanese Patent Application No. 2020-094666), the content of which is incorporated herein by reference.

Explanation of Reference Numerals

[0118] 1 Optical member 2 Resin composition layer 3 Semiconductor light-emitting element 4 Substrate 5 Adhesive layer 6 Cover 10 Optical element 20 Ultraviolet light emitting device

Claims

1. An optical element comprising a resin composition layer and an optical member that transmits ultraviolet rays, wherein the resin composition layer is made of a resin composition in which metal oxide nanoparticles are dispersed in a resin, Refractive index n of the resin composition with respect to d-line (wavelength 587.6 nm) ｄ (C) and the refractive index n of the resin ｄ (R) satisfy the relation that n ｄ (C) - n ｄ (R) ≥ 0.03 the resin is at least one of an amorphous fluororesin and a silicone resin whose main skeleton structure is silsesquioxane, the resin composition layer is formed on at least a partial region of the surface of the optical member and is used in an ultraviolet light emitting device, the optical member is composed of inorganic glass, the adhesive strength between the optical member and the adherend by the resin composition layer is 5 N / mm2 or more and 20 N / mm2 or less in shear strength, The inorganic glass has a maximum absorption coefficient αmax in the wavelength range of 260 to 400 nm of 0.2 mm －１ An optical element which is the following ultraviolet highly transmissive glass.

2. The optical element according to claim 1, wherein the band gap of the metal oxide nanoparticles is 4.8 eV or more.

3. The metal oxide nanoparticles are Gd ２ O ３ , HfO ２ , La ２ O ３ , Y ２ O ３ , Yb ２ O ３ , ZrO ２ , Al ２ O ３ , and at least one kind of nanoparticle selected from the group consisting of SiO ２ , the optical element according to claim 1 or 2.

4. The optical element according to any one of claims 1 to 3, wherein the average primary particle diameter of the metal oxide nanoparticles is 2 to 80 nm.

5. The optical element according to any one of claims 1 to 4, wherein the content of the metal oxide nanoparticles is 15% by mass or more and 70% by mass or less.

6. The refractive index n of the resin composition ｄ The optical element according to any one of claims 1 to 5, wherein (C) is 1.39 or more.

7. The optical element according to any one of claims 1 to 6, wherein the average value of the transmittance in the wavelength range of 260 to 400 nm of the resin composition is 70% or more.

8. The refractive index n of the optical member with respect to the d line (wavelength 587.6 nm) ｄ (O) and the refractive index n of the resin composition layer ｄ (C)' satisfy Δn ｄ = |n ｄ (O) - n ｄ (C)'| ≤ 0.35, and the optical element according to any one of claims 1 to 7

9. The optical element according to any one of claims 1 to 8, wherein the ultraviolet light emitting device includes a semiconductor light emitting element having a peak wavelength λ(D) in the wavelength range of 250 to 400 nm.

10. The optical element according to claim 9, wherein the resin composition layer is used for adhesion between the light emitting surface of the semiconductor light emitting element and the optical member as the adherend.

11. An ultraviolet light emitting device having a substrate, a semiconductor light emitting element provided on the substrate, and an optical element provided on the semiconductor light emitting element, wherein the optical element includes a resin composition layer and an optical member that transmits ultraviolet rays, the optical member is composed of inorganic glass, the adhesive strength between the light emitting surface of the semiconductor light emitting element and the optical member by the resin composition layer is 5 N / mm2 or more and 20 N / mm2 or less in shear strength, The inorganic glass has a maximum absorption coefficient αmax in the wavelength range of 260 to 400 nm of 0.2 mm －１ is the following ultraviolet highly transmissive glass, the resin composition layer is made of a resin composition in which metal oxide nanoparticles are dispersed in a resin, The refractive index n of the resin composition layer with respect to the d line (wavelength 587.6 nm) ｄ (C)' and the refractive index n of the resin ｄ (R) and n ｄ (C)' - n ｄ (R) ≧ 0.03 the resin is at least one of an amorphous fluororesin and a silicone resin whose main skeleton structure is silsesquioxane, the resin composition layer is formed on at least a partial region of the surface of the optical member, An ultraviolet light-emitting device in which the optical element is provided on a light-emitting surface of the semiconductor light-emitting element via the resin composition layer.

12. The ultraviolet light-emitting device according to claim 11, wherein a peak wavelength λ(D) of light emitted by the semiconductor light-emitting element is in a wavelength range of 250 to 400 nm.

13. The refractive index n of the resin composition layer at the peak wavelength λ(D) ｏ The ultraviolet light emitting device according to claim 12, wherein (C)' is 1.4 or more.

14. The refractive index n of the optical member at the peak wavelength λ(D) ｏ (O) and the refractive index n of the resin composition layer ｏ (C)' satisfy Δn ｏ = |n ｏ (O) - n ｏ (C)'| ≤ 0.42, and the ultraviolet light emitting device according to claim 12 or 13

15. The ultraviolet light-emitting device according to any one of claims 11 to 14, wherein the semiconductor light-emitting element has a flip-chip structure or a vertical structure.

16. The ultraviolet light-emitting device according to any one of claims 11 to 15, wherein the resin composition layer covers at least a part of a side surface of the semiconductor light-emitting element.

17. The ultraviolet light-emitting device according to any one of claims 11 to 16, wherein a part of the optical member is in contact with the substrate or adhered to the substrate.

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