Light-emitting device

Abstract

Provided is a light-emitting device equipped with a luminescent element that emits ultraviolet light, the ultraviolet light having a luminescence peak wavelength of 220-320 nm, and the luminescent element having a radiant flux exceeding 20 mW. The light-emitting device comprises a first member, a second member, and a silicone resin layer with which the first member and the second member are bonded to each other. The first member, the silicone resin layer, and the second member transmit the ultraviolet light in that order. In a first interface, which is the interface between the silicone resin layer and the first member, the shortest distance (A) from the center of the first interface to the perimeter of the first interface is 1.00 mm or less. The silicone resin layer has a thickness (B) of 0.6 μm or larger. The ratio of the shortest distance (A) from the center of the first interface to the perimeter of the first interface to the thickness (B) of the silicone resin layer, (A) / (B), is 900 or less, when the two are represented with the same unit.

Description

Light-emitting device

[0001] The present disclosure relates to a light emitting device.

[0002] Patent Documents 1 and 2 disclose light-emitting devices that emit ultraviolet light. The light-emitting device includes a light-emitting element, a lens, and a silicone resin layer that bonds the light-emitting element and the lens. In Patent Document 1, the radiant flux of the light-emitting element is, for example, 1 mW. In Patent Document 2, the radiant flux of the light-emitting element is, for example, 15 mW or 20 mW. The radiant flux is the radiant energy emitted per unit time.

[0003] U.S. Patent No. 10,074,784 Japanese Patent No. 6,817,187

[0004] A known light-emitting device includes a first member, a second member, and a silicone resin layer that bonds the first member and the second member. The first member, the silicone resin layer, and the second member transmit ultraviolet light in this order. When the ultraviolet light emitted by the light-emitting element has a short emission peak wavelength and a strong radiant flux, the silicone resin layer may become colored. As a result, the transmittance of ultraviolet light through the silicone resin layer may decrease, and the ultraviolet light extraction efficiency may decrease.

[0005] One aspect of the present disclosure provides a technique that can suppress coloration of a silicone resin layer even when the emission peak wavelength of ultraviolet light emitted by a light-emitting element is short and the radiant flux of the light-emitting element is strong.

[0006] A light-emitting device according to one aspect of the present disclosure includes a light-emitting element that emits ultraviolet light, the ultraviolet light having an emission peak wavelength of 220 nm to 320 nm, and a radiant flux of the light-emitting element exceeding 20 mW. The light-emitting device includes a first member, a second member, and a silicone resin layer that bonds the first member and the second member. The first member, the silicone resin layer, and the second member transmit the ultraviolet light in this order. When viewed from a direction perpendicular to a first interface between the silicone resin layer and the first member, the entire first interface is located inside the periphery of a second interface between the silicone resin layer and the second member. The shortest distance (A) from the center of the first interface to the periphery of the first interface is 1.00 mm or less. The thickness (B) of the silicone resin layer is 0.6 μm or more. The ratio (A / B) of the shortest distance (A) from the center of the first interface to the periphery of the first interface to the thickness (B) of the silicone resin layer is 900 or less when units are all consistent.

[0007] According to one aspect of the present disclosure, even if the emission peak wavelength of the ultraviolet light emitted by the light-emitting element is short and the radiant flux of the light-emitting element is strong, coloration of the silicone resin layer can be suppressed.

[0008] FIG. 1 is a cross-sectional view showing a light-emitting device according to one embodiment. FIG. 2 is a plan view showing an example of the positional relationship between a first interface and a second interface. FIG. 3 is a cross-sectional view showing an example of a state in which a coloring component escapes from a silicone resin layer. FIG. 4 is a cross-sectional view showing a first example of a test apparatus. FIG. 5 is a cross-sectional view showing a second example of a test apparatus. FIG. 6 is a cross-sectional view showing a third example of a test apparatus. FIG. 7 is a cross-sectional view showing a fourth example of a test apparatus.

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and their description may be omitted. In the specification, the symbol "to" indicating a range of values ​​means that the values ​​before and after the symbol are included as the lower and upper limits.

[0010] 1 to 3, a light emitting device 1 according to one embodiment will be described. The light emitting device 1 includes a light emitting element 2, a lens 3, and a silicone resin layer 5 that bonds the light emitting element 2 to the lens 3. A part of the light emitting element 2 (specifically, for example, a substrate 22 described below) is an example of the first member, and the lens 3 is an example of the second member.

[0011] The light-emitting element 2 emits ultraviolet light. A portion of the light-emitting element 2, the silicone resin layer 5, and the lens 3 transmit the ultraviolet light, in this order. The ultraviolet light has a peak emission wavelength of, for example, 220 nm to 320 nm, and preferably 260 nm to 290 nm. The "peak emission wavelength" refers to the wavelength at which the output value is highest in the spectral distribution of the emitted light. The radiant flux of the light-emitting element 2 is, for example, greater than 20 mW, preferably 35 mW or more, and more preferably 40 mW or more. From the viewpoint of the heat dissipation properties of the light-emitting element 2, the radiant flux of the light-emitting element 2 may be 120 mW or less. The radiant flux is the radiant energy emitted per unit time. The radiant flux is measured in accordance with CIE 127:2007.

[0012] The light-emitting element 2 has, for example, a substrate 22 and a semiconductor layer 23. The light-emitting element 2 has, for example, a flip-chip structure. When the light-emitting element 2 has a flip-chip structure, ultraviolet light generated in the semiconductor layer 23 is emitted through the substrate 22. The substrate 22 is a transparent substrate that transmits ultraviolet light. The surface of the substrate 22 facing the lens 3 is the light-emitting surface 21 of the light-emitting element 2.

[0013] The substrate 22 is made of, for example, a sapphire substrate or an aluminum nitride substrate. An aluminum nitride substrate is a substrate made of a single crystal of aluminum nitride. A sapphire substrate or an aluminum nitride substrate is a transparent substrate that transmits ultraviolet light. The thickness t of the substrate 22 is, for example, 0.05 mm to 2 mm.

[0014] The semiconductor layer 23 is provided on the opposite side of the substrate 22 from the lens 3. The semiconductor layer 23 emits light when a voltage is applied to it. An electrode for applying a voltage to the semiconductor layer 23 is not shown, but is formed on the opposite side of the substrate 22 from the semiconductor layer 23 so as not to block the ultraviolet light traveling from the semiconductor layer 23 to the substrate 22. This prevents a decrease in light extraction efficiency.

[0015] The light-emitting element 2 may be bonded to a mounting substrate via solder bumps. The mounting substrate is, for example, a ceramic substrate made of sintered aluminum nitride, sintered aluminum oxide, or LTCC (Low Temperature Co-fired Ceramics) on which electrodes are formed.

[0016] The lens 3 suppresses total reflection of ultraviolet light and improves the extraction efficiency of ultraviolet light. The lens 3 has an opposing surface 31 facing the light emission surface 21 of the light-emitting element 2, and a convex curved surface 32 facing away from the opposing surface 31. The ultraviolet light emitted by the light-emitting element 2 is incident on the opposing surface 31 and exits from the convex curved surface 32. The convex curved surface 32 is a dome-shaped curved surface whose center protrudes further than the periphery.

[0017] The lens 3 may be a spherical lens or an aspherical lens. Although not shown, the lens 3 may have a flange that protrudes radially outward from the periphery of the convex curved surface 32.

[0018] Although not shown, the convex curved surface 32 of the lens 3 may have irregularities that prevent reflection of ultraviolet light generated by the light emitting element 2. The irregularities of the convex curved surface 32 have, for example, a moth-eye structure, and prevent ultraviolet light traveling from the inside of the lens 3 to the outside from being reflected back into the lens 3, thereby improving the efficiency of extracting ultraviolet light.

[0019] Although not shown, the light emitting device 1 may be provided with an anti-reflection coating on the convex curved surface 32 of the lens 3. The anti-reflection coating prevents ultraviolet light traveling from the inside of the lens 3 to the outside from being reflected back into the lens 3, thereby improving the efficiency of extracting ultraviolet light. A general anti-reflection coating is used.

[0020] Although not shown, the convex curved surface 32 of the lens 3 may have irregularities that scatter the ultraviolet light generated by the light emitting element 2. The irregularities of the convex curved surface 32 scatter the ultraviolet light emitted from the convex curved surface 32, thereby emitting the ultraviolet light over a wider range.

[0021] The material of the lens 3 is, for example, oxide glass. Oxide glass can be processed by various processing methods such as thermoforming or grinding and polishing, and a processing method suitable for the shape of the lens 3 can be selected. Examples of oxide glass include soda-lime glass, alkali-free glass, chemically strengthened glass, and lanthanum borate glass. In order to reduce the loss of ultraviolet light caused by the lens 3, a material with low ultraviolet light absorption rate is suitable as the material of the lens 3, and the material of the lens 3 is preferably quartz, quartz glass, or sapphire.

[0022] The silicone resin layer 5 bonds the light emitting surface 21 of the light emitting element 2 and the opposing surface 31 of the lens 3 so that they face each other. It is preferable that the light emitting surface 21 of the light emitting element 2 and the opposing surface 31 of the lens 3 each have a flat surface at least in the area where they overlap. The opposing surface 31 of the lens 3 is larger than the light emitting surface 21 of the light emitting element 2, and may have a curved surface in the area extending beyond the light emitting surface 21.

[0023] The surface roughness Ra of the light emitting surface 21 of the light emitting element 2 is, for example, 0.01 nm to 5 nm. When a fine uneven structure is formed on the light emitting surface 21 to improve the extraction efficiency of ultraviolet light, the surface roughness Ra of the light emitting surface 21 is 5 nm to 50 nm. The surface roughness Ra of the opposing surface 31 of the lens 3 is, for example, 0.01 nm to 5 nm. The surface roughness Ra is the arithmetic mean roughness as defined in JIS B0601:2001.

[0024] Incidentally, the shorter the emission peak wavelength of the ultraviolet light emitted by the light-emitting element 2, the more likely it is that the silicone resin layer 5 will be colored. Also, the stronger the radiant flux of the light-emitting element 2, the more likely it is that the silicone resin layer 5 will be colored. If the silicone resin layer 5 is colored, the transmittance of ultraviolet light will decrease, and the efficiency of extracting ultraviolet light will decrease.

[0025] The present inventors have found that, even when the peak wavelength of the ultraviolet light emitted by the light-emitting element 2 is short and the radiant flux of the light-emitting element 2 is large, coloration of the silicone resin layer 5 can be suppressed by adjusting the size of the light-emitting surface 21 and the thickness of the silicone resin layer 5. When the peak wavelength of the ultraviolet light emitted by the light-emitting element 2 is large or the radiant flux of the light-emitting element 2 is small, the size of the light-emitting surface 21 and the thickness of the silicone resin layer 5 are considered not to affect the coloration of the silicone resin layer 5. The present inventors have found that, even when the peak wavelength of the ultraviolet light is 220 nm to 320 nm and the radiant flux of the light-emitting element 2 is greater than 20 mW, as long as the conditions described below are met, the coloring component 51 of the silicone resin layer 5 is likely to escape from the silicone resin layer 5 into the surrounding atmosphere (e.g., air or nitrogen), as shown in FIG. 3 , and the silicone resin layer 5 is unlikely to be colored. Conditions for suppressing coloration of the silicone resin layer 5 are described below.

[0026] The interface between the silicone resin layer 5 and the light-emitting element 2 is called the first interface. In this embodiment, the first interface is the entire light-emitting surface 21, but it may be a part of the light-emitting surface 21. In addition, the interface between the silicone resin layer 5 and the lens 3 is called the second interface. In this embodiment, the second interface is the entire opposing surface 31, but it may be a part of the opposing surface 31.

[0027] 2 , when viewed from a direction perpendicular to the light emitting surface 21, the entire light emitting surface 21 is disposed inside the periphery of the opposing surface 31. Therefore, the length of the path along which the coloring component 51 of the silicone resin layer 5 escapes from the silicone resin layer 5 into the surrounding atmosphere can be represented by the shortest distance (A) from the center of the light emitting surface 21 to the periphery of the light emitting surface 21.

[0028] When the light exit surface 21 is a square, half the length of one side of the square is the shortest distance (A). Note that the shape of the light exit surface 21 is not limited to a square.

[0029] The shortest distance (A) is preferably 1.00 mm or less. If the shortest distance (A) is 1.00 mm or less, the length of the path along which the coloring component 51 escapes from the silicone resin layer 5 into the surrounding atmosphere is short, and coloring of the silicone resin layer 5 can be suppressed. The shortest distance (A) is more preferably 0.50 mm or less. From the viewpoint of the intensity of the radiant flux, the shortest distance (A) is preferably 0.20 mm or more.

[0030] 3, the width of the path through which the coloring component 51 escapes from the silicone resin layer 5 to the surrounding atmosphere can be represented by the thickness (B) of the silicone resin layer 5. Furthermore, the aspect ratio (ratio of the path length to the path width) of the path through which the coloring component 51 escapes from the silicone resin layer 5 to the surrounding atmosphere can be represented by the ratio (A / B) when the units of the shortest distance (A) and the thickness (B) are the same.

[0031] The thickness (B) is preferably 0.6 μm or more. If the thickness (B) is 0.6 μm or more, the light emitting element 2 and the lens 3 can be bonded to each other. The thickness (B) is more preferably 1.2 μm or more, and even more preferably 2.0 μm or more. From the viewpoints of adhesiveness and suppression of coloration, the larger the thickness (B), the better, but the thickness (B) may be 10 μm or less.

[0032] The ratio (A / B) is preferably 900 or less. If the ratio (A / B) is 900 or less, the aspect ratio of the above-mentioned path is small, the coloring component 51 is easily removed, and coloring of the silicone resin layer 5 can be suppressed. The ratio (A / B) is more preferably 550 or less, and even more preferably 390 or less. From the viewpoint of suppressing coloring, the smaller the ratio (A / B), the better, but it may be 50 or more.

[0033] Silicone resins have organosiloxy units. The organosiloxy units include monofunctional organosiloxy units called M units, difunctional organosiloxy units called D units, trifunctional organosiloxy units called T units, and tetrafunctional organosiloxy units called Q units. Although Q units are units that do not have an organic group bonded to a silicon atom (an organic group having a carbon atom bonded to a silicon atom), they are considered organosiloxy units (silicon-containing bonded units) in this specification. The monomers that form M units, D units, T units, and Q units are also referred to as M monomers, D monomers, T monomers, and Q monomers, respectively.

[0034] In this specification, the term "total organosiloxy units" refers to the total of M units, D units, T units, and Q units. The ratio of the number (molar amount) of M units, D units, T units, and Q units can be calculated from the peak area ratio value by 29Si-NMR.

[0035] In the organosiloxy unit, the siloxane bond is a bond in which two silicon atoms are bonded via one oxygen atom, so the number of oxygen atoms per silicon atom in the siloxane bond is considered to be 1 / 2, and in the formula, O １／２ More specifically, for example, in one D unit, one silicon atom is bonded to two oxygen atoms, and each oxygen atom is bonded to a silicon atom of another unit, so the formula is -O １／２ - (R) ２ Si—O １／２ - (R represents a hydrogen atom or an organic group). １／２ Since there are two units, the D unit is (R) ２ SiO ２／２ (In other words, (R) ２ It is usually expressed as SiO.

[0036] In the following description, an oxygen atom O bonded to another silicon atom ＊ is an oxygen atom bonding two silicon atoms, and refers to the oxygen atom in the bond represented by Si—O—Si. ＊ is present between the silicon atoms of two organosiloxy units.

[0037] M unit is (R) ３ SiO １／２ Here, R represents a hydrogen atom or an organic group. The number (here, 3) after (R) indicates that three hydrogen atoms or organic groups are bonded to the silicon atom. In other words, the M unit is a unit consisting of one silicon atom, three hydrogen atoms or organic groups, and one oxygen atom O. ＊ More specifically, the M unit has three hydrogen atoms or organic groups bonded to one silicon atom and an oxygen atom O bonded to one silicon atom. ＊ It has.

[0038] D unit means (R) ２ SiO ２／２ (R represents a hydrogen atom or an organic group). That is, the D unit has one silicon atom, two hydrogen atoms or organic groups bonded to the silicon atom, and an oxygen atom O bonded to another silicon atom. ＊ It is a unit that has two of these.

[0039] T units are RSiO ３／２ (R represents a hydrogen atom or an organic group). That is, the T unit has one silicon atom, one hydrogen atom or an organic group bonded to the silicon atom, and an oxygen atom O bonded to another silicon atom. ＊ It is a unit that has three of these.

[0040] Q units are SiO ２ That is, the Q unit has one silicon atom and an oxygen atom O bonded to another silicon atom. ＊ It is a unit that has four of these.

[0041] Examples of organic groups include alkyl groups, aryl groups, aralkyl groups, and halogen-substituted monovalent hydrocarbon groups. Examples of alkyl groups include methyl groups, ethyl groups, propyl groups, butyl groups, pentyl groups, hexyl groups, cyclohexyl groups, and heptyl groups. Examples of aryl groups include phenyl groups, tolyl groups, xylyl groups, and naphthyl groups. Examples of aralkyl groups include benzyl groups and phenethyl groups. Examples of halogen-substituted monovalent hydrocarbon groups include halogenated alkyl groups. Examples of halogenated alkyl groups include chloromethyl groups, 3-chloropropyl groups, and 3,3,3-trifluoropropyl groups. Preferable organic groups are unsubstituted or halogen-substituted monovalent hydrocarbon groups having 1 to 12 carbon atoms (preferably about 1 to 10 carbon atoms).

[0042] The silicone resin constituting the silicone resin layer 5 is RSiO because of its durability against ultraviolet rays. ３／２ and organosiloxy units (T units) represented by the formula: ２ It is preferable that the organosiloxy unit (Q unit) contains at least one specific organosiloxy unit selected from the group consisting of organosiloxy units (Q units) represented by the following formula:

[0043] The proportion of the specific organosiloxy units is preferably 60 mol% or more, and more preferably 80 mol% or more, relative to the total organosiloxy units. There is no particular upper limit, but it is often 100 mol% or less. The proportion of the number (molar amount) of T units and Q units can be calculated from the peak area ratio by 29Si-NMR.

[0044] Silicone resins are usually obtained by curing (crosslinking) curable silicones. In other words, silicone resins are the cured products of curable silicones. Curable silicones are classified into condensation reaction type silicones, addition reaction type silicones, ultraviolet curable silicones, and electron beam curable silicones depending on their curing mechanism, and any of them can be used.

[0045] The method for forming the silicone resin layer 5 is not particularly limited, and examples thereof include spin coating, spray coating, bar coating, gravure coating, screen printing, inkjet coating, etc. Alternatively, a method can be used in which a silicone resin layer formed on a support member such as a release film is transferred to an optical member such as a light-emitting element or a lens.

[0046] In order to bond the optical member and the light-emitting element 2 with sufficient adhesive strength using the silicone resin layer 5, it is preferable to thoroughly clean the surfaces of the optical member and the light-emitting element 2 to be bonded. The cleaning method is not particularly limited, but cleaning can be performed using, for example, a hydrocarbon solvent such as ethanol or acetone, a fluorine-based solvent such as AS-300 (manufactured by AGC Inc.), or an aqueous cleaner such as an alkaline detergent. Furthermore, adhesive strength can also be improved by subjecting the surfaces to be bonded to a surface activation treatment. For example, UV ozone treatment, atmospheric pressure plasma treatment, excimer UV treatment, corona treatment, etc. can be used.

[0047] The process of bonding the optical member and the light-emitting element 2 is not particularly limited, but for example, a method of bonding the optical member and the light-emitting element 2 under atmospheric pressure or a method of bonding them under vacuum can be used. Furthermore, the optical member and the light-emitting element 2 can be bonded while being heated to facilitate bonding.

[0048] In order to obtain sufficient adhesive strength, a heat treatment or an autoclave treatment (heating and pressure treatment) may be performed after bonding the optical member and the light emitting element 2. Furthermore, after bonding, the light emitting element 2 may be made to emit light to perform an aging treatment of the silicone resin layer 5. The heat treatment, autoclave treatment, and aging treatment described above may be performed in an atmospheric pressure atmosphere or an inert gas atmosphere.

[0049] The experimental data will be explained below. Examples 1 to 4, 6 to 9, 13, and 15 to 16 are working examples, and Examples 5, 10 to 12, 14, and 17 to 20 are comparative examples.

[0050] [Example 1] In Example 1, as shown in FIG. 4, a test device 100 was fabricated by placing a stack 110 on the light emission surface 121 of a light-emitting element 120. The stack 110, which will be described in detail later, was fabricated by bonding a first quartz substrate 111 and a second quartz substrate 112 with a silicone resin layer 113. The interface between the first quartz substrate 111 and the silicone resin layer 113 was the first interface, and the interface between the second quartz substrate 112 and the silicone resin layer 113 was the second interface. The first quartz substrate 111 had a square main surface with sides of 0.8 mm and a thickness of 0.17 mm. The shortest distance (A) between the center of the first interface and the periphery of the first interface was 0.40 mm. The second quartz substrate 112 had a square main surface with sides of 5 mm and a thickness of 0.5 mm. The stack 110 was placed on the light-emitting element 120 with the first quartz substrate 111 facing downward. After preparing the test device 100 in this manner, the light-emitting element 120 was continuously lit at 70°C for 500 hours, and the change in the radiant flux (W) of the ultraviolet light emitted from the laminate 110 was measured. The radiant flux of the ultraviolet light emitted from the laminate 110 was measured using an integrating sphere. The light-emitting element 120 had an ultraviolet light emission peak wavelength of 265 nm, a light-emitting surface 121 that was a square with sides of 0.8 mm, and a radiant flux of the light-emitting element 120 of 40 mW. The radiant flux of the light-emitting element 120 was measured without the laminate 110 being placed on the light-emitting surface 121 of the light-emitting element 120.

[0051] The laminate 110 was fabricated using the following procedure. First, the organic adhesive solution A1 described below was spin-coated onto the surface of a 50 μm-thick PET film (Cosmoshine A4160 manufactured by Toyobo Co., Ltd.), and the film was heated at 100°C for 5 minutes using a hot plate to form a silicone resin layer 113. Next, the silicone resin layer 113 was bonded to the surface of the second quartz substrate 112, and heated and pressurized at 1.0 MPa and 120°C for 10 minutes using an autoclave treatment device. Next, the silicone resin layer 113 was cooled to room temperature, and the PET film was peeled off. Next, the second quartz substrate 112 with the silicone resin layer 113 attached was heated in an oven at 150°C for 30 minutes. Then, the first quartz substrate 111 was superimposed on the silicone resin layer 113, and the film was heated in an oven at 200°C for 30 minutes to fabricate the laminate 110. The thickness (B) of the silicone resin layer 113 was 2.0 μm.

[0052] The organic adhesive solution A1 was prepared according to the following procedure. First, triethoxymethylsilane (179 g), toluene (300 g), and acetic acid (5 g) were charged into a flask, stirred at 25°C for 20 minutes, and then heated to 60°C and reacted for 12 hours to obtain a crude reaction liquid. Next, the crude reaction liquid was cooled to 25°C, and then washed three times with water (300 g). Next, toluene was distilled off from the crude reaction liquid under reduced pressure to prepare a slurry. Next, the slurry was dried overnight in a vacuum dryer to obtain a white organopolysiloxane compound (resin A2). The mixed liquid obtained by mixing resin A2 and toluene was filtered using a filter with a pore size of 0.45 μm to prepare organic adhesive solution A1.

[0053] [Example 2] In Example 2, a test device 100 having the same structure as Example 1 was fabricated, except that the thickness (B) of the silicone resin layer 113 was changed to 4.0 μm, and the change in the radiant flux of ultraviolet light emitted from the laminate 110 was measured in the same manner as in Example 1.

[0054] [Example 3] In Example 3, a test device 100 having the same structure as in Example 1 was fabricated, except that the thickness (B) of the silicone resin layer 113 was changed to 1.0 μm, and the change in the radiant flux of ultraviolet light emitted from the laminate 110 was measured in the same manner as in Example 1.

[0055] [Example 4] In Example 4, a test device 100 having the same structure as in Example 1 was fabricated, except that the thickness (B) of the silicone resin layer 113 was changed to 0.8 μm, and the change in the radiant flux of ultraviolet light emitted from the laminate 110 was measured in the same manner as in Example 1.

[0056] [Example 5] In Example 5, a test device 100 having the same structure as in Example 1 was fabricated, except that the thickness (B) of the silicone resin layer 113 was changed to 0.2 μm, and the change in the radiant flux of ultraviolet light emitted from the laminate 110 was measured in the same manner as in Example 1.

[0057] [Example 6] In Example 6, as shown in FIG. 5, a test device 200 was fabricated by placing a rectangular frame-shaped aluminum sheet 230 and a laminate 210 in this order on the light emission surface 221 of a light-emitting element 220. The laminate 210, like the laminate 110, was fabricated by bonding a first quartz substrate 211 and a second quartz substrate 212 with a silicone resin layer 213. The interface between the first quartz substrate 211 and the silicone resin layer 213 was the first interface, and the interface between the second quartz substrate 212 and the silicone resin layer 213 was the second interface. The first quartz substrate 211 had a square main surface with sides of 0.6 mm and a thickness of 0.17 mm. The shortest distance (A) between the center of the first interface and the periphery of the first interface was 0.29 mm. The second quartz substrate 212 had a square main surface with sides of 5 mm and a thickness of 0.5 mm. The thickness (B) of the silicone resin layer 213 was 2.0 μm. The thickness of the aluminum sheet 230 was 12 μm, and the opening of the aluminum sheet 230 was a square with sides of 0.5 mm. The laminate 210 was placed on the light-emitting element 220 via the aluminum sheet 230, with the first quartz substrate 211 facing downward. An air layer of the same thickness as the aluminum sheet 230 was formed between the light-emitting element 220 and the first quartz substrate 211. The thickness (D) of the air layer was 0.012 mm. After producing the test device 200 in this manner, the light-emitting element 220 was continuously lit at 70° C. for 500 hours, and the change in the radiant flux (W) of the ultraviolet light emitted from the laminate 210 was measured. The radiant flux of the ultraviolet light emitted from the laminate 210 was measured using an integrating sphere. The light emitting element 220 had an ultraviolet light emission peak wavelength of 265 nm, a light emitting surface 221 that was a square with a length of 0.8 mm and a width of 0.8 mm, and a radiant flux of 60 mmW. The radiant flux of the light emitting element 220 was measured without placing the aluminum sheet 230 and the laminate 210 on the light emitting surface 221 of the light emitting element 220.

[0058] Example 7 In Example 7, a test device 200 having the same structure as in Example 6 was fabricated, except that the length of one side of the opening of the aluminum sheet 230 was changed to 0.3 mm, the length of one side of the main surface of the first quartz substrate 211 was changed to 0.4 mm, thereby changing the shortest distance (A) between the center of the first interface and the periphery of the first interface to 0.19 mm, and the radiant flux of the light-emitting element 220 was changed to 80 mW. In this case, a change in the radiant flux of ultraviolet light emitted from the laminate 210 was measured in the same manner as in Example 6.

[0059] Example 8 In Example 8, as shown in FIG. 6 , a test device 300 was fabricated by disposing a stack 310 above a light-emitting element 320 at a distance. The stack 310, like the stack 110, was fabricated by bonding a first quartz substrate 311 and a second quartz substrate 312 with a silicone resin layer 313. The interface between the first quartz substrate 311 and the silicone resin layer 313 was the first interface, and the interface between the second quartz substrate 312 and the silicone resin layer 313 was the second interface. The first quartz substrate 311 had a square main surface with sides of 1.2 mm and a thickness of 0.17 mm. The shortest distance (A) between the center of the first interface and the periphery of the first interface was 0.59 mm. The second quartz substrate 312 had a square main surface with sides of 5 mm and a thickness of 0.5 mm. The thickness (B) of the silicone resin layer 313 was 2.0 μm. The laminate 310 was placed with the first quartz substrate 311 facing downward, and the silicone resin layer 313 was placed on the spacer 330 so as to form an air layer between the first quartz substrate 311 and the light-emitting element 320. The thickness (D) of the air layer was 0.050 mm. After fabricating the test device 300 in this manner, the light-emitting element 320 was continuously lit at 70°C for 500 hours, and the change in the radiant flux (W) of the ultraviolet light emitted from the laminate 310 was measured. The radiant flux of the ultraviolet light emitted from the laminate 310 was measured using an integrating sphere. The light-emitting element 320 had an ultraviolet light emission peak wavelength of 265 nm, a light-emitting surface 321 that was a square with sides of 0.8 mm, and a radiant flux of the light-emitting element 320 of 80 mW. The radiant flux of the light-emitting element 320 was measured without placing the laminate 310 above the light-emitting surface 321 of the light-emitting element 320. By setting the thickness (D) of the air layer to 0.050 mm, it was possible to irradiate the entire first interface with ultraviolet light.

[0060] Example 9 In Example 9, a test device 300 having the same structure as in Example 8 was fabricated, except that the length of one side of the main surface of the first quartz substrate 311 was changed to 1.5 mm, thereby changing the shortest distance (A) between the center of the first interface and the periphery of the first interface to 0.77 mm, and the thickness of the spacer 330 was changed, thereby changing the thickness (D) of the air layer to 0.100 mm. The change in the radiant flux of ultraviolet light emitted from the stack 310 was measured in the same manner as in Example 8. Note that by setting the thickness (D) of the air layer to 0.100 mm, it was possible to irradiate the entire first interface with ultraviolet light.

[0061] Example 10 In Example 10, a test device 300 having the same structure as in Example 8 was fabricated, except that the length of one side of the main surface of the first quartz substrate 311 was changed to 2.3 mm, thereby changing the shortest distance (A) between the center of the first interface and the periphery of the first interface to 1.15 mm, and the thickness of the spacer 330 was changed, thereby changing the thickness (D) of the air layer to 0.200 mm. The change in the radiant flux of ultraviolet light emitted from the stack 310 was measured in the same manner as in Example 8. Note that by setting the thickness (D) of the air layer to 0.200 mm, it was possible to irradiate the entire first interface with ultraviolet light.

[0062] [Example 11] In Example 11, a test device 300 was fabricated with the same structure as in Example 10, except that the radiant flux of the light-emitting element 220 was changed to 40 mW, and the change in the radiant flux of ultraviolet light emitted from the laminate 310 was measured in the same manner as in Example 10.

[0063] Example 12 In Example 12, a test device 300 having the same structure as in Example 8 was fabricated, except that the length of one side of the main surface of the first quartz substrate 311 was changed to 2.7 mm, thereby changing the shortest distance (A) between the center of the first interface and the periphery of the first interface to 1.33 mm, and the thickness of the spacer 330 was changed, thereby changing the thickness (D) of the air layer to 0.250 mm. The change in the radiant flux of ultraviolet light emitted from the stack 310 was measured in the same manner as in Example 8. Note that by setting the thickness (D) of the air layer to 0.250 mm, it was possible to irradiate the entire first interface with ultraviolet light.

[0064] [Example 13] In Example 13, a test device 300 having the same structure as in Example 8 was fabricated, except that the length of one side of the main surface of the first quartz substrate 311 was changed to 1.5 mm, thereby changing the shortest distance (A) between the center of the first interface and the periphery of the first interface to 0.77 mm, the thickness of the air layer (D) was changed to 0.100 mm, and the thickness (B) of the silicone resin layer 313 was changed to 1.5 μm. The change in the radiant flux of ultraviolet light emitted from the laminate 310 was measured in the same manner as in Example 8. Note that by changing the thickness (D) of the air layer to 0.100 mm, ultraviolet light could be irradiated over the entire first interface.

[0065] [Example 14] In Example 14, a test device 300 having the same structure as in Example 8 was fabricated, except that the length of one side of the main surface of the first quartz substrate 311 was changed to 1.5 mm, thereby changing the shortest distance (A) between the center of the first interface and the periphery of the first interface to 0.77 mm, the thickness of the air layer (D) was changed to 0.100 mm, and the thickness (B) of the silicone resin layer 313 was changed to 0.8 μm. The change in the radiant flux of ultraviolet light emitted from the laminate 310 was measured in the same manner as in Example 8. Note that by changing the thickness (D) of the air layer to 0.100 mm, ultraviolet light could be irradiated over the entire first interface.

[0066] [Example 15] In Example 15, as shown in FIG. 7 , a test device 400 was fabricated by bonding a hemispherical quartz lens 410 and a light-emitting element 420 with a silicone resin layer 430. The test device 400 was fabricated using the following procedure. First, the organic adhesive solution A1 described above was applied by spin coating to the surface of a 50 μm-thick PET film (Cosmoshine A4160 manufactured by Toyobo Co., Ltd.), and the film was heated at 100°C for 5 minutes using a hot plate to form a silicone resin layer 430. Next, the silicone resin layer 430 was bonded to the flat surface of the hemispherical quartz lens 410 (a circle with a diameter of 3 mm), and then heated and pressurized at 1.0 MPa and 120°C for 10 minutes using an autoclave treatment device. Next, the silicone resin layer 430 was cooled to room temperature, and the PET film was peeled off. Next, the quartz lens 410 with the silicone resin layer 430 attached was heated in an oven at 150°C for 30 minutes. The light-emitting element 420 was then superimposed on the silicone resin layer 430 and heated in an oven at 200°C for 30 minutes to produce a test device 400. The interface between the light-emitting element 420 and the silicone resin layer 430 was the first interface, and the interface between the quartz lens 410 and the silicone resin layer 430 was the second interface. The shortest distance (A) between the center of the first interface and the periphery of the first interface was 0.40 mm. The thickness (B) of the silicone resin layer 430 was 2.0 μm. After producing the test device 400 in this manner, the light-emitting element 420 was continuously lit at 70°C for 500 hours, and the change in the radiant flux (W) of ultraviolet light emitted from the convex curved surface of the quartz lens 410 was measured. The radiant flux of ultraviolet light emitted from the convex curved surface of the quartz lens 410 was measured using an integrating sphere. The light-emitting element 420 emitted ultraviolet light at a peak wavelength of 265 nm, had a light-emitting surface 421 that was a square with sides of 0.8 mm, and had a radiant flux of 40 mW. The radiant flux of the light-emitting element 420 was measured without the silicone resin layer 430 and the quartz lens 410 being placed on the light-emitting surface 421 of the light-emitting element 420.

[0067] Example 16 In Example 16, a test device 400 was fabricated having the same structure as in Example 15, except that the thickness (B) of the silicone resin layer 430 was changed to 4.0 μm, and the change in the radiant flux of ultraviolet light emitted from the convex curved surface of the quartz lens 410 was measured in the same manner as in Example 15.

[0068] Example 17 In Example 17, a test device 400 was fabricated having the same structure as in Example 15, except that the thickness (B) of the silicone resin layer 430 was changed to 0.5 μm, and the change in the radiant flux of ultraviolet light emitted from the convex curved surface of the quartz lens 410 was measured in the same manner as in Example 15.

[0069] Example 18 In Example 18, a test device 400 having the same structure as in Example 15 was fabricated, except that the length of one side of light emitting surface 421 was changed to 1.0 mm, thereby changing the shortest distance (A) between the center of the first interface and the periphery of the first interface to 0.50 mm, and the radiant flux of light emitting element 420 was changed to 8 mW. The test device 400 was then measured for change in the radiant flux of ultraviolet light emitted from the convex curved surface of quartz lens 410 in the same manner as in Example 15.

[0070] Example 19 In Example 19, a test device 400 having the same structure as in Example 15 was fabricated, except that the length of one side of light emitting surface 421 was changed to 3.2 mm, thereby changing the shortest distance (A) between the center of the first interface and the periphery of the first interface to 1.60 mm, and the radiant flux of light emitting element 420 was changed to 12 mW. In the same manner as in Example 15, the change in the radiant flux of ultraviolet light emitted from the convex curved surface of quartz lens 410 was measured.

[0071] [Example 20] In Example 19, a test device 400 having the same structure as in Example 15 was fabricated, except that the length of one side of light emitting surface 421 was changed to 3.2 mm, thereby changing the shortest distance (A) between the center of the first interface and the periphery of the first interface to 1.60 mm, and the radiant flux of light emitting element 420 was changed to 20 mW. The change in the radiant flux of ultraviolet light emitted from the convex curved surface of quartz lens 410 was measured in the same manner as in Example 15.

[0072] [Evaluation Results] The evaluation results for Examples 1 to 20 are shown in Table 1. In Table 1, "radiant flux maintenance rate" indicates the ratio (%) of the radiant flux at the end of lighting to the radiant flux at the start of lighting. The higher the radiant flux maintenance rate, the higher the transparency of the silicone resin layer and the less coloring of the silicone resin layer. In Table 1, "Good" for "Adhesion" indicates that adhesion was possible, and "Poor" for "Adhesion" indicates that adhesion was not possible.

[0073] In Table 1, a "good" in the "evaluation" column indicates that the radiant flux maintenance rate was 90% or more and adhesion was possible. A "fair" in the "evaluation" column indicates that the radiant flux maintenance rate was 80% or more but less than 90% and adhesion was possible. A "bad" in the "evaluation" column indicates that the radiant flux maintenance rate was less than 80% or adhesion was impossible.

[0074]

[0075] In Examples 1 to 4, 6 to 9, 13, and 15 to 16, (A) was 1.00 mm or less, (B) was 0.6 μm or more, and (A / B) was 900 or less, so the radiant flux maintenance factor was 80% or more and adhesion was possible, unlike in Examples 5, 10 to 12, and 14. Furthermore, in Examples 1 to 2, 6 to 9, and 15 to 16, (A) was 1.00 mm or less, (B) was 0.6 μm or more, and (A / B) was 390 or less, so the radiant flux maintenance factor was 90% or more and adhesion was possible.

[0076] Examples 18 to 20 are examples in which the radiant flux of the light-emitting element is 20 mW or less. In Examples 19 to 20, the radiant flux of the light-emitting element is greater than that of Example 18, and (A) exceeds 1.00 mm, but the radiant flux maintenance factor is 90% or more, the same as in Example 18. It can be seen that when the radiant flux of the light-emitting element is 20 mW or less, (A) and (A / B) have almost no effect on the radiant flux maintenance factor.

[0077] The following supplementary notes are disclosed regarding the above-described embodiments, etc. [Supplementary Note 1] A light-emitting device includes a light-emitting element that emits ultraviolet light, the ultraviolet light having an emission peak wavelength of 220 nm to 320 nm, and a radiant flux of the light-emitting element exceeding 20 mW, the light-emitting device including a first member, a second member, and a silicone resin layer that bonds the first member and the second member, the first member, the silicone resin layer, and the second member transmitting the ultraviolet light in this order, when viewed from a direction perpendicular to a first interface between the silicone resin layer and the first member, the entire first interface being located inside the periphery of a second interface between the silicone resin layer and the second member, the shortest distance (A) from the center of the first interface to the periphery of the first interface is 1.00 mm or less, and the silicone resin layer has a thickness (B) of 0.6 μm or more, A light-emitting device, wherein the ratio (A / B) of the shortest distance (A) from the center of the first interface to the periphery of the first interface to the thickness (B) of the silicone resin layer, when units are all consistent, is 900 or less. [Appendix 2] The light-emitting device according to Appendix 1, wherein the ratio (A / B) of the shortest distance (A) from the center of the first interface to the periphery of the first interface to the thickness (B) of the silicone resin layer, when units are all consistent, is 550 or less. [Appendix 3] The light-emitting device according to Appendix 1, wherein the ratio (A / B) of the shortest distance (A) from the center of the first interface to the periphery of the first interface to the thickness (B) of the silicone resin layer, when units are all consistent, is 390 or less. [Appendix 4] The light-emitting device according to any one of Appendices 1 to 3, wherein the ratio (A / B) of the shortest distance (A) from the center of the first interface to the periphery of the first interface to the thickness (B) of the silicone resin layer, when units are all consistent, is 50 or more. [Appendix 5] The light-emitting device according to any one of Appendices 1 to 4, wherein the shortest distance (A) from the center of the first interface to the periphery of the first interface is 0.50 mm or less. [Appendix 6] The light-emitting device according to any one of Appendices 1 to 5, wherein the thickness (B) of the silicone resin layer is 2.0 μm or more. [Appendix 7] The light-emitting device according to any one of Appendices 1 to 6, wherein the silicone resin layer contains at least one specific organosiloxy unit selected from the group consisting of T units and Q units.[Appendix 8] The light-emitting device according to Appendices 7, wherein a proportion of the specific organosiloxy units is 60 mol % or more relative to all organosiloxy units. [Appendix 9] The light-emitting device according to any one of Appendices 1 to 8, wherein the radiant flux of the light-emitting element is 35 mW or more. [Appendix 10] The light-emitting device according to any one of Appendices 1 to 9, wherein the ultraviolet light has an emission peak wavelength of 260 nm to 290 nm. [Appendix 11] The light-emitting device according to any one of Appendices 1 to 10, wherein the first member is a part of the light-emitting element. [Appendix 12] The light-emitting device according to any one of Appendices 1 to 11, wherein the second member is a lens.

[0078] Although the light-emitting device according to the present disclosure has been described above, the present disclosure is not limited to the above-described embodiments, etc. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. Naturally, these also fall within the technical scope of the present disclosure.

[0079] This application claims priority based on Japanese Patent Application No. 2023-099791 filed with the Japan Patent Office on June 19, 2023, the entire contents of which are incorporated herein by reference.

[0080] REFERENCE SIGNS LIST 1 Light emitting device 2 Light emitting element 21 Light emitting surface (first interface) 3 Lens 31 Opposing surface (second interface) 5 Silicone resin layer

Claims

1. A light emitting device comprising a light emitting element that emits ultraviolet light, the ultraviolet light having an emission peak wavelength of 220 nm to 320 nm, and a radiant flux of the light emitting element exceeding 20 mW, the light emitting device comprising: a first member; a second member; and a silicone resin layer that bonds the first member and the second member; the first member, the silicone resin layer, and the second member transmit the ultraviolet light in this order; when viewed from a direction perpendicular to a first interface that is an interface between the silicone resin layer and the first member, the entire first interface is disposed inside the periphery of a second interface that is an interface between the silicone resin layer and the second member; the first interface has a shortest distance (A) from the center of the first interface to the periphery of the first interface of 1.00 mm or less; and the silicone resin layer has a thickness (B) of 0.6 μm or more; a ratio (A / B) of the shortest distance (A) from the center of the first interface to the periphery of the first interface to the thickness (B) of the silicone resin layer in uniform units is 900 or less.

2. The light emitting device according to claim 1, wherein the ratio (A / B) of the shortest distance (A) from the center of the first interface to the periphery of the first interface to the thickness (B) of the silicone resin layer, in standard units, is 550 or less.

3. The light emitting device according to claim 1, wherein the ratio (A / B) of the shortest distance (A) from the center of the first interface to the periphery of the first interface to the thickness (B) of the silicone resin layer, in standard units, is 390 or less.

4. The light emitting device according to claim 1, wherein the ratio (A / B) of the shortest distance (A) from the center of the first interface to the periphery of the first interface to the thickness (B) of the silicone resin layer is 50 or more when the units are all uniform.

5. The light emitting device according to claim 1, wherein the shortest distance (A) from the center of said first interface to the periphery of said first interface is 0.50 mm or less.

6. The light-emitting device according to claim 1, wherein the thickness (B) of the silicone resin layer is 2.0 μm or more.

7. The light-emitting device according to claim 1, wherein said silicone resin layer contains at least one specific organosiloxy unit selected from the group consisting of T units and Q units.

8. The light emitting device according to claim 7, wherein the proportion of said specific organosiloxy units is 60 mol % or more based on the total organosiloxy units.

9. The light emitting device according to any one of claims 1 to 8, wherein the radiant flux of said light emitting element is 35 mW or more.

10. The light emitting device according to any one of claims 1 to 8, wherein the ultraviolet light has an emission peak wavelength of 260 nm to 290 nm.

11. The light emitting device according to any one of claims 1 to 8, wherein the first member is a part of the light emitting element.

12. The light emitting device according to any one of claims 1 to 8, wherein the second member is a lens.