Optical device

Abstract

To provide an optical device capable of emitting or receiving ultraviolet light with high light extraction efficiency or light capture efficiency.SOLUTION: The optical device 10 includes an optical device (LED chips 12) that emits or receives ultraviolet light, and a plastic lens 13 that covers the optical device, and the optical device includes a substrate 12a and a plurality of semiconductors 12a stacked on the substrate 12b. The plastic lens 13 covers the optical elements from the side of the substrate 12b among the plurality of semiconductors 12a and the substrate 12a, and is made of an organic-inorganic hybrid material that is a composite of silica nanoparticles and polydimethylsiloxane, and the organic-inorganic hybrid material is represented by a chemical formula in which three types of organosilicon including a unit Si-Si CH3, organosilicon including a unit Si-Si CH2CH2CF3, and Si are repeatedly bonded.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to optical devices, and more particularly to optical devices including optical elements that emit or receive ultraviolet light. [Background technology]

[0002] LEDs that emit ultraviolet light, particularly deep ultraviolet light, are expected to be used for sterilizing water or inactivating airborne viruses such as the new coronavirus, and various proposals have been made for their use (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-73702 Summary of the Invention [Problem to be solved by the invention]

[0004] The ultraviolet light emitted from an LED is released into the air through the aluminum nitride (AlN) or sapphire substrate, but the difference in refractive index between them reduces the light extraction efficiency. For example, when using sapphire as a substrate to extract ultraviolet light into the air, if the emission from the light-emitting layer covers a range of 180°, the light extraction efficiency is approximately 15%, and if the emission covers a range of 60°, the light extraction efficiency is approximately 40%, meaning that most of the light is not extracted and is absorbed within the LED.

[0005] Therefore, an object of the present disclosure is to provide an optical device that can emit or receive ultraviolet light with high light extraction efficiency or light capture efficiency. [Means for solving the problem]

[0006] In order to achieve the above object, an optical device according to one embodiment of the present disclosure comprises an optical element that emits or receives ultraviolet light, and a resin member that covers the optical element, wherein the optical element includes a substrate and a plurality of semiconductor layers stacked on the substrate, and the resin member is made of an organic-inorganic hybrid material that is a composite of silica nanoparticles and polydimethylsiloxane, and covers the optical element from the substrate side of the plurality of semiconductor layers and the substrate.

[0007] The organic-inorganic hybrid material is preferably represented by a chemical formula in which three types of units, Si—CH 3 -containing organosilicon, Si—CH 2 CH 2 CF 3 -containing organosilicon, and silicon are repeatedly bonded. [Effects of the Invention]

[0008] The present disclosure provides an optical device that can emit or receive ultraviolet light with high light extraction efficiency or light capture efficiency. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing the configuration of an optical device according to an embodiment. [Figure 2A] FIG. 2A is a perspective photograph of the optical device according to the example. [Figure 2B] FIG. 2B is a perspective photograph of the optical device shown in FIG. 2A taken from a low angle. [Figure 2C] FIG. 2C is a photograph showing a top view of the LED chip when the resin lens is removed from the optical device shown in FIG. 2A. [Figure 2D] FIG. 2D is a schematic cross-sectional view of the optical device shown in FIG. 2A. [Figure 3A] FIG. 3A is a diagram showing a comparison of the light output characteristics between an optical device according to an example of a medium chip size having the structure shown in FIGS. 2A to 2D and an optical device according to a comparative example that does not have a resin lens. [Figure 3B]FIG. 3B is a diagram showing a comparison of the light output characteristics between an optical device according to an example with a large chip size having the structure shown in FIGS. 2A to 2D and an optical device according to a comparative example that does not have a resin lens. [Figure 4A] FIG. 4A is a diagram showing typical optical output characteristics of an optical device according to an embodiment of a medium chip size having the structure shown in FIGS. 2A-2D. [Figure 4B] FIG. 4B is a diagram showing typical optical output characteristics of an optical device according to an embodiment of a large chip size having the structure shown in FIGS. 2A to 2D. [Figure 5] FIG. 5 is a diagram showing a comparison of the external quantum efficiency between the optical device according to the example and the optical device according to the comparative example. [Figure 6A] FIG. 6A is a flowchart showing an outline of a method for manufacturing an optical device according to an embodiment. [Figure 6B] FIG. 6B is a flowchart showing an outline of a method for manufacturing an optical device according to a modified embodiment. [Figure 7A] FIG. 7A shows the chemical formulas of the basic materials used in the resin synthesis step of the flowchart shown in FIG. [Figure 7B] FIG. 7B is a diagram illustrating the same explanation as in FIG. 7A using the chemical formula of a polymer. [Figure 8] FIG. 8 is a diagram illustrating detailed chemical formulas of materials used in the resin synthesis step of the flowchart shown in FIGS. 6A and 6B. [Figure 9] FIG. 9 is a diagram illustrating details of the resin synthesis step (procedure using a catalyst) in the flowchart shown in FIGS. 6A and 6B. [Figure 10] FIG. 10 shows the results of thermal analysis and transparency analysis of the synthesized organic-inorganic hybrid material. [Figure 11A] FIG. 11A shows the optical absorption spectrum of an organic-inorganic hybrid material synthesized using CF3-TMOS as a fluorine-containing silane coupling agent. [Figure 11B]FIG. 11B shows the optical absorption spectrum of an organic-inorganic hybrid material synthesized using CF3(CF2)5-TEOS as a fluorine-containing silane coupling agent. [Figure 11C] FIG. 11C is a diagram showing the difference in the addition effect between two types of fluorine-containing silane coupling agents. [Figure 11D] FIG. 11D is a diagram showing a comparison of the optical absorption spectra of the organic-inorganic hybrid material according to the embodiment and the organic-inorganic hybrid material according to the prior art. [Figure 12] FIG. 12 shows an experimental setup for measuring the transmittance of the synthesized organic-inorganic hybrid material. [Figure 13A] FIG. 13A is a diagram showing the measurement results of the transmittance of the synthesized organic-inorganic hybrid material. [Figure 13B] FIG. 13B is a diagram showing the measurement results showing the difference in transmittance of organic-inorganic hybrid materials depending on the curing temperature during synthesis. [Figure 14] FIG. 14 is a plot of the time-dependent change in transmittance at two wavelengths, 262 nm and 278 nm, for the synthesized organic-inorganic hybrid material. [Figure 15] FIG. 15 is a diagram showing the estimated mechanism by which the transmittance of an organic-inorganic hybrid material is improved by irradiating it with deep ultraviolet light. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that each embodiment described below represents a specific example of the present disclosure. The numerical values, shapes, materials, components, the arrangement and connection of the components, steps, the order of steps, and the like shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, each drawing is not necessarily an exact illustration. In each drawing, substantially identical components are assigned the same reference numerals, and duplicate explanations are omitted or simplified.

[0011] 1 is a cross-sectional view showing the configuration of an optical device 10 according to an embodiment. The optical device 10 is an optical device that emits or receives ultraviolet light (in this embodiment, an optical device that emits deep ultraviolet light), and is composed of a wiring substrate 11, an LED chip 12, and a resin lens 13.

[0012] The wiring board 11 is a circuit board and a heat dissipation board on which a wiring pattern for supplying power to the LED chip 12 is formed, and is, for example, a ceramic package on which a copper foil wiring pattern is formed.

[0013] The LED chip 12 is an example of an optical element that emits or receives ultraviolet light. In this embodiment, the LED chip 12 is an LED chip that emits, for example, 265 nm deep ultraviolet light. The LED chip 12 is formed by stacking a substrate 12a, a semiconductor layer 12b on the substrate 12a, and an electrode 12c on the semiconductor layer 12b. The chip is turned upside down, and the electrode 12c is surface-mounted on the wiring substrate 11 with solder. The substrate 12a is made of, for example, aluminum nitride or sapphire. The semiconductor layer 12b includes a buffer layer, an electron injection layer, a light-emitting layer, an electron blocking layer, a hole injection layer, and the like, each formed of, for example, an AlN layer and an AlGaN layer. The electrode 12c is made of, for example, gold.

[0014] The LED chip 12 is not limited to these materials as long as it is an element that emits or receives ultraviolet light, and may be made of, for example, AlN, AlGaN, or AlGaInN, which are expressed as AlxGayIn(1-xy)N (0≦x≦1, 0≦y≦1, (x+y)≦1). The LED chip 12 and the wiring substrate 11 may be provided with a reflective layer, such as an Al layer, that reflects ultraviolet light emitted downward from the LED chip 12.

[0015] Resin lens 13 is an example of a resin member. In this embodiment, it is an optical lens made of an organic-inorganic hybrid material that encapsulates and covers the LED chip in a dome shape. It is a colorless, transparent body with a refractive index close to that of substrate 12a. For example, resin lens 13 has a refractive index close to that of sapphire substrate 12a (approximately 1.83) for ultraviolet light with a wavelength of 265 nm. This reduction in the refractive index difference prevents the ultraviolet light emitted from semiconductor layer 12b of LED chip 12 and passing through substrate 12a from being totally reflected at the interface between substrate 12a and resin lens 13, and is efficiently emitted to resin lens 13.

[0016] In this embodiment, resin lens 13 covers the entire LED chip 12 on wiring substrate 11 in a hemispherical shape, and ultraviolet light emitted upward from LED chip 12 within a range of 180 degrees (hemisphere) is efficiently released into the outside world (air, etc.). In other words, due to the shape of resin lens 13, ultraviolet light emitted from LED chip 12 and passing through resin lens 13 is incident at an angle close to perpendicular to the interface between resin lens 13 and the outside world, thereby suppressing total reflection and allowing the light to be efficiently released into the outside world.

[0017] The organic-inorganic hybrid material constituting the resin lens 13 is a composite of silica nanoparticles (SiO2) and polydimethylsiloxane (PDMS), and contains a fluoroalkyl group (here, CF3CH2CH2). More specifically, it is a material exemplified by the chemical formula 1 below.

[0018] [ka]

[0019] The above formula 1 illustrates that the three types of units shown below, organosilicon (a) containing Si-CH3, organosilicon (b) containing Si-CH2CH2CF3, and silicon (c), are repeatedly bonded in various numbers.

[0020] [ka]

[0021] The resin lens 13 according to this embodiment has the following features due to the shape and material described above.

[0022] (1) It has high transmittance for deep ultraviolet light with wavelengths of 250 nm or more. (2) It has a high refractive index, that is, a refractive index close to that of the sapphire substrate 12a. (3) It has durability that does not decrease in light absorption rate even when exposed to ultraviolet light. (4) It is easy to mold.

[0023] Fig. 2A is a perspective photograph of the optical device 10a according to the example. Fig. 2B is a perspective photograph of the optical device 10a shown in Fig. 2A viewed from a low angle. Fig. 2C is a top photograph of the LED chip 12 viewed from the optical device 10a shown in Fig. 2A after removing the resin lens 13. Fig. 2D is a schematic cross-sectional view of the optical device 10a shown in Fig. 2A.

[0024] As shown in FIGS. 2A to 2D, the optical device 10a according to this embodiment corresponds to the optical device 10 shown in FIG. 1, except that a reflector 14 is provided on the wiring substrate 11 of the optical device 10, surrounding the side surfaces of the resin lens 13. As shown in FIG. 2D, the optical device 10a is 6.8 mm square and the LED chip 12 is 0.6 mm square (medium chip size) or 1.0 mm square (large chip size) in plan view. The resin lens 13 is hemispherical with a radius of approximately 1 mm or 1.5 mm, and the reflector 14 has an inner diameter of 5.1 mm and a thickness of 0.4 mm. The reflector 14 has a taper (a slope whose thickness increases from the inner periphery to the outer periphery) on its inner periphery to reflect upward the ultraviolet light that has passed from the LED chip 12 through the side surfaces of the resin lens 13. This results in a light distribution characteristic in which the ultraviolet light emitted upward from the optical device 10a has a stronger directivity.

[0025] 3A is a graph showing a comparison of the optical output characteristics of an optical device 10a according to an embodiment of the present invention having a medium chip size (0.6 mm square) and the structure shown in FIGS. 2A to 2D, and an optical device according to a comparative example that does not have a resin lens. More specifically, (a) of FIG. 3A shows the output power (vertical axis, unit: mW) versus the applied current (horizontal axis, unit: mA), and (b) of FIG. 3A shows the external quantum efficiency (vertical axis, unit: %) versus the applied current (horizontal axis, unit: mA). The solid lines show the characteristics of three samples of optical devices 10a according to the embodiment, and the dashed lines show the characteristics of the optical device sample according to the comparative example.

[0026] As shown in FIG. 3A (a), the medium-sized optical device 10a according to the embodiment achieved an output power of 28 mW at an applied current of 100 mA. Furthermore, as shown in FIG. 3A (b), the medium-sized optical device 10a according to the embodiment achieved an external quantum efficiency of 5% or more, with a maximum external quantum efficiency of 6.20%. As can be seen from FIGS. 3A (a) and (b), the medium-sized optical device 10a according to the embodiment exhibits significantly improved light output characteristics compared to the optical device according to the comparative example, which does not have a resin lens. This also proves that the refractive index of the resin lens 13 is close to the refractive index of the substrate 12a of the LED chip 12.

[0027] 3B is a diagram showing a comparison of the light output characteristics of an optical device 10a according to an embodiment having a large chip size (1.0 mm square) and the structure shown in FIGS. 2A to 2D and an optical device according to a comparative example that does not have a resin lens. (a) and (b) of FIG. 3B show the same light output characteristics as those of FIG. 3A. The solid lines show the characteristics of the three optical device samples 10a according to the embodiment, and the dashed lines show the characteristics of the optical device sample according to the comparative example.

[0028] As shown in FIG. 3B (a), the large-chip-sized optical device 10a according to the example achieved an output power of 93 mW at an applied current of 400 mA. Furthermore, as shown in FIG. 3B (b), the large-chip-sized optical device 10a according to the example achieved an external quantum efficiency of 5% or more, with a maximum external quantum efficiency of 5.45%. As can be seen from FIGS. 3B (a) and (b), the large-chip-sized optical device 10a according to the example exhibits significantly improved light output characteristics compared to the optical device according to the comparative example that does not have a resin lens. This also proves that the refractive index of the resin lens 13 is close to the refractive index of the substrate 12a of the LED chip 12.

[0029] 4A shows typical optical output characteristics of an optical device 10a according to an embodiment of the present invention having a medium chip size (0.6 mm square) and the structure shown in FIGS. 2A to 2D. More specifically, (a) of FIG. 4A shows the output power (vertical axis, unit: mW) versus the applied current (horizontal axis, unit: mA), (b) of FIG. 4A shows the external quantum efficiency (vertical axis, unit: %) versus the applied current (horizontal axis, unit: mA), and (c) of FIG. 4A shows the normalized intensity (vertical axis, unit: arbitrary unit (log)) versus the output wavelength (horizontal axis, unit: nm). As can be seen from (c) of FIG. 4A, the medium chip size optical device 10a according to the embodiment emits intense deep ultraviolet light with a peak at a wavelength of 265 nm.

[0030] 4B is a diagram showing typical optical output characteristics of an optical device 10a according to an embodiment having a large chip size (1.0 mm square) and the structure shown in FIGS. 2A to 2D. (a) to (c) of FIG. 4B show optical output characteristics similar to those of (a) of FIG. 4B. (c) of FIG. 4B shows that even the large chip size optical device 10a according to the embodiment emits strong deep ultraviolet light with a peak at a wavelength of 265 nm.

[0031] FIG. 5 is a graph comparing the external quantum efficiency of the optical device 10a according to the example and the optical device according to the comparative example. The horizontal axis represents the emission wavelength (unit: nm), and the vertical axis represents the external quantum efficiency (unit: %). The external quantum efficiency of the optical device according to the comparative example is data published in various publicly known documents. Focusing on the emission wavelength of 265 nm, the optical device 10a according to the example achieves an external quantum efficiency of 5.2% at an applied current of 126 mA (and an output power of 107 mW at an applied current of 500 mA) and an external quantum efficiency of 6.2% at an applied current of 50 mA (and an output power of 28 mW at an applied current of 100 mA). In other words, the optical device 10a according to the example can be said to be a deep-ultraviolet light-emitting device with the world's highest efficiency (external quantum efficiency of 5% or more) and output power (output power exceeding 100 mW).

[0032] Next, a method for manufacturing the optical device 10 according to the present embodiment configured as above will be described.

[0033] 6A is a flowchart showing an outline of a method for manufacturing the optical device 10 according to the embodiment. First, an optical element (here, an LED chip 12) that emits or receives ultraviolet light is prepared (preparation step S10).

[0034] Next, a resin lens 13 is fabricated to cover the LED chip 12 (resin lens fabrication step S20). This resin lens fabrication step S20 includes a resin synthesis step S21 and a sealing step S22, which will be described below.

[0035] In the resin lens preparation step S20, an organic-inorganic hybrid material is synthesized by mixing at least silanol-terminated polydimethylsiloxane (hereinafter also referred to as "PDMS") and a silica precursor, polydiethoxysiloxane (hereinafter also referred to as "PDEOS"). More specifically, a mixture of PDMS, PDEOS, and a fluorine-containing silane coupling agent is mixed with dibutyltin dilaurate (BuSn(OCOC)). 11 H 23 )2) is added as a catalyst to carry out the sol-gel reaction, a low-temperature glass production technique.

[0036] In the sealing step S22, the LED chip 12 is covered in a hemispherical shape with the synthesized organic-inorganic hybrid material from the side of the substrate 12a of the LED chip 12. More specifically, the synthesized organic-inorganic hybrid material is dropped onto the LED chip 12, and then the organic-inorganic hybrid material is cured at room temperature or in a heated state to produce the resin lens 13. If heated, for example, the process is performed at 150°C for 30 minutes, and if at room temperature, the process is left for 1 to 2 days. Note that instead of applying and curing, a procedure may be used in which a hemispherical, hat-shaped resin lens 13 is made of the organic-inorganic hybrid material using a mold, and the resin lens 13 is then placed over the LED chip 12 to seal it using the organic-inorganic hybrid material as an adhesive.

[0037] 6A, the resin lens 13 can be produced in a separate process and then sealed in sealing step S22 using the organic-inorganic hybrid material as an adhesive. The resin lens produced in the separate process is not limited to a hemispherical shape, and can also be a flat shape with concentric grooves like a Fresnel lens, or an arrangement of multiple hemispherical lenses. Furthermore, the material for the lens produced in the separate process is not limited to resin, and materials such as quartz glass can also be used.

[0038] Finally, the manufactured optical device 10 is energized for a certain period of time to perform aging, which causes the optical device 10 to emit ultraviolet light, thereby increasing the transmittance of the resin lens 13 (transmittance increasing step S30). Note that in the transmittance increasing step S30, the transmittance of the resin lens 13 may be increased by irradiating the resin lens 13 with ultraviolet light emitted from another ultraviolet light emitting device instead of or in addition to the ultraviolet light emitted by the optical device 10.

[0039] Fig. 6B is a flowchart showing an outline of a method for manufacturing optical device 10 according to a modified embodiment. Components with the same functions as those in Fig. 6A are designated by the same numbers. In Fig. 6B, an organic-inorganic hybrid material is used as the resin sealing material for the ultraviolet optical semiconductor device instead of resin lens 13 of the optical element that emits or receives ultraviolet light, thereby improving the durability and weather resistance of the optical device.

[0040] First, in preparation step S10, an optical element is prepared.

[0041] Next, a resin member (made of the same material as the resin lens 13) is prepared to cover the LED chip 12 (resin member preparation step S200). This resin member preparation step S200 includes a resin synthesis step S210 and a sealing step S220, which will be described next.

[0042] In the resin synthesis step S210, an organic-inorganic hybrid material is synthesized by mixing at least PDMS and PDEOS. More specifically, a mixture of PDMS, PDEOS, and a fluorine-containing silane coupling agent is mixed with dibutyltin dilaurate (BuSn(OCOC)). 11 H 23 )2) is added as a catalyst to carry out the sol-gel reaction, a low-temperature glass production technique.

[0043] In the sealing step S220, the LED chip 12 is covered from the substrate 12a side of the LED chip 12 with the synthesized organic-inorganic hybrid material. More specifically, the synthesized organic-inorganic hybrid material is applied or dropped onto the LED chip 12, and then cured at room temperature or in a heated state to form a resin sealing film. If heated, the process is performed at 100 to 180°C for 10 to 60 minutes, for example. If heated, the process is performed by leaving it at room temperature for 1 to 2 days, completing a resin seal that improves the durability and weather resistance of the optical device 10 while minimizing the decrease in transmittance.

[0044] Figure 7A shows the chemical formulas of the basic materials used in resin synthesis step S21 in the flowchart shown in Figure 6. This figure shows the procedure for synthesizing an organic-inorganic hybrid material (Figure 7A(d), "PDMS / SiO2") by adding dibutyltin dilaurate (Figure 7A(c)) as a catalyst to a mixture of PDMS (molecular weight 4200) (Figure 7A(a)) and PDEOS (Figure 7A(b)). The sol-gel reaction proceeds as follows: PDMS (cSt), molecular weight, hydroxyl group weight percentage (%(OH)), hydroxyl group kg equivalent ((OH)-Eq / kg), specific gravity, and refractive index) are listed in Table 1 below. Note that the addition of a fluorine-containing silane coupling agent is omitted in Figure 7A.

[0045] [Table 1]

[0046] Figure 7B illustrates the same explanation as in Figure 7A, but expressed in chemical formulas. More specifically, (a) of Figure 7B shows the materials (PDMS, PDEOS) used in the synthesis and the finished product (resin lens) in easy-to-understand terms and photographs, and (b) of Figure 7B shows the chemical formula of the material corresponding to (a) of Figure 7A. As illustrated in Figure 7B, the resin lens 13 constituting the optical device 10 is a deep-ultraviolet LED lens made from an organic-inorganic hybrid material that combines the moldability of silicone resin with the transparency of quartz by focusing on the sol-gel method, a low-temperature glass manufacturing technology, and applying organic-inorganic hybrid technology.

[0047] Figure 8 illustrates the detailed chemical formulas of the materials used in the resin synthesis step S21 in the flowchart shown in Figure 6. This figure shows that PDMS (Figure 8(a)), PDEOS (Figure 8(b)), and a fluorine-containing silane coupling agent (Figure 8(c)) are mixed and left at room temperature to undergo co-hydrolysis and condensation in a single reaction known as a sol-gel reaction, resulting in the synthesis of an organic-inorganic hybrid material (Figure 8(d)). The chemical formulas of each material are also shown. The fluorine-containing silane coupling agent shown in Figure 8(c) is at least one of trimethoxy(3,3,3-trifluoropropyl)silane (CF3-TMOS) and trimethoxy(1H,1H,2H,2H-heptadecafluorodecyl)silane (CF3(CF2)5-TEOS).

[0048] Figure 9 is a diagram explaining the details of resin synthesis step S21 (procedure using a catalyst) in the flowchart shown in Figure 6. Here, we examine whether the sol-gel reaction (gelation) proceeds (yes / no) and how the silica weight content (SiO2 Content) changes depending on the combination of the type and weight of PDMS, PDEOS, and catalyst (catalyst). Several synthesis examples of varying molecular weights are shown. The molecular weight of PDMS was 4,200, and the sol-gel reaction was carried out at room temperature for 7 days.

[0049] As can be seen from Figure 9, when zinc acetylacetonate (Zn(acac)2) and dibutyltin oxide (Bu2SnO) were used as catalysts, the sol-gel reaction did not proceed and the reaction mixture remained liquid. On the other hand, when dibutyltin dilaurate (Bu2Sn(OCOC)) was used as catalyst, the sol-gel reaction did not proceed and the reaction mixture remained liquid. 11 H 23 When 2) was used, the reaction proceeded and a colorless and transparent organic-inorganic hybrid material was obtained. Furthermore, by changing the mixing ratio of PDMS and PDEOS, organic-inorganic hybrid materials with different silica contents were synthesized.

[0050] Figure 10 shows the results of thermal analysis and transparency analysis of the synthesized organic-inorganic hybrid materials. More specifically, Figure 10(a) shows the heat flow (vertical axis, unit: mW) versus temperature (horizontal axis, unit: °C). The graph shows the temperature dependence of heat flow for organic-inorganic hybrid materials with different silica (SiO2) contents (30 wt% and 40 wt%). It can be seen that as the silica content increases (from 30 wt% to 40 wt%), the glass transition temperature increases (from Tg = 13 °C to Tg = 33 °C). Since a higher glass transition temperature indicates a harder material, using a larger amount of PDEOS during synthesis results in a harder organic-inorganic hybrid material.

[0051] Figure 10(b) shows a photograph showing the transparency of the organic-inorganic hybrid material placed on English paper. The synthesized organic-inorganic hybrid material was highly transparent, and no polymer precipitation was observed in the silica. This indicates that the synthesized organic-inorganic hybrid material is a uniform mixture of polydimethylsiloxane, an organic polymer, and silica, an inorganic material, at the molecular level.

[0052] Figure 11A shows the optical absorption spectra of organic-inorganic hybrid materials synthesized using trimethoxy(3,3,3-trifluoropropyl)silane (CF3-TMOS) as a fluorine-containing silane coupling agent. More specifically, Figure 11A (a) shows the chemical formulas of the materials (PDMS, PDEOS, and CF3-TMOS) used in the synthesis of the organic-inorganic hybrid materials. Figure 11A (b) shows the composition (wt % of PDMS, silica (SiO2), and fluoroalkyl group (CF3CH2CH2)) of each sample (runs 1 to 4) of the synthesized organic-inorganic hybrid materials. Figure 11A (c) shows the optical absorption spectra of each sample (runs 1 to 4) (horizontal axis: wavelength (nm), vertical axis: absorptivity (%)). Note that dibutyltin dilaurate was used as a catalyst in the synthesis of the organic-inorganic hybrid materials.

[0053] A colorless, transparent solid was obtained for all samples (runs 1 to 4). Sample run 1 was a hybrid consisting of only PDMS and silica, without the addition of a fluorine-containing silane coupling agent. As can be seen from the optical absorption spectra of samples (runs 2 and 3), which were synthesized with the addition of a fluorine-containing silane coupling agent, the transmittance in the ultraviolet region was improved compared to sample run 1, which did not contain a fluorine-containing silane coupling agent. However, sample run 4, which also contained a fluorine-containing silane coupling agent, showed a decrease in transmittance. Therefore, it is clear that there is an appropriate amount of fluoroalkyl groups, such as keeping it below 18% by weight.

[0054] Figure 11B shows the optical absorption spectra of organic-inorganic hybrid materials synthesized using trimethoxy(1H,1H,2H,2H-heptadecafluorodecyl)silane (CF3(CF2)5-TEOS) as a fluorine-containing silane coupling agent. Specifically, Figure 11B (a) shows the chemical formulas of the materials (PDMS, PDEOS, and CF3(CF2)5-TEOS) used in the synthesis of the organic-inorganic hybrid materials. Figure 11B (b) shows the composition (wt % of PDMS, silica (SiO2), and fluoroalkyl group (CF3(CH2)5)) of each sample (runs 1 to 3) of the synthesized organic-inorganic hybrid materials. Figure 11B (c) shows the optical absorption spectra of each sample (runs 1 to 3) (horizontal axis: wavelength (nm), vertical axis: absorptivity (%)). Note that dibutyltin dilaurate was used as a catalyst in the synthesis of the organic-inorganic hybrid materials.

[0055] The molar concentration of the fluorine-containing silane coupling agent was the same as in the experiment shown in Figure 11A, so the weight percentage of the fluoroalkyl group was large. A colorless, transparent solid was obtained for all samples, runs 1 to 3. However, in this experiment, the transmittance at a wavelength of around 250 nm decreased as the fluoroalkyl group content increased, possibly due to the high weight ratio of the fluoroalkyl group.

[0056] Figure 11C shows the difference in the effect of adding two types of fluorine-containing silane coupling agents. In other words, it summarizes the experimental results of Figures 11A and 11B. More specifically, in Figure 11C(a) (left side of Figure 11C), the top row shows the chemical formula of CF3-TMOS added during synthesis, the middle row shows the optical absorption spectrum of the synthesized organic-inorganic hybrid material, and the bottom row shows the weight percentage of the composition of each sample of the synthesized organic-inorganic hybrid material. In Figure 11C(b) (right side of Figure 11C), the top row shows the chemical formula of CF3(CF2)5-TEOS added during synthesis, the middle row shows the optical absorption spectrum of the synthesized organic-inorganic hybrid material, and the bottom row shows the weight percentage of the composition of each sample of the synthesized organic-inorganic hybrid material.

[0057] Figure 11C shows that the organic-inorganic hybrid material synthesized with the addition of CF3-TMOS has a higher transmittance at a wavelength of around 250 nm than the organic-inorganic hybrid material synthesized with the addition of CF3(CF2)5-TEOS. In other words, the longer the fluoroalkyl group, the lower the transmittance. From these results, it is thought that the transmittance of the organic-inorganic hybrid material is not due to the length of the fluoroalkyl group, but rather to the amount of fluoro groups contained in the organic-inorganic hybrid material.

[0058] FIG. 11D shows a comparison of the optical absorption spectra of an organic-inorganic hybrid material according to an embodiment and a conventional organic-inorganic hybrid material. More specifically, (a) of FIG. 11D shows the optical absorption spectrum of an organic-inorganic hybrid material according to an embodiment, which corresponds to (a) of FIG. 11C. (b) of FIG. 11D shows the optical absorption spectrum of a conventional organic-inorganic hybrid material. The conventional organic-inorganic hybrid material is disclosed in Bae et al., RSC Advances 2016, 6, 26826. Researchers at the Korea Advanced Institute of Science and Technology (KAST) combined a sol-gel reaction of vinylsilane, hydromethylsiloxane oligomer, and a fluorine-containing silane coupling agent with a hydrosilylation reaction to introduce fluorine into a hybrid composed of siloxane oligomer and silica through a two-step reaction process. This hybrid material was reported as an encapsulant for deep-ultraviolet LEDs.

[0059] 11D, the transmittance of the organic-inorganic hybrid material according to the embodiment at a wavelength of 250 nm is higher than that of the conventional technology, exceeding 60%. This is thought to be because, unlike the conventional technology, the embodiment does not use vinylsilane but polydiethoxysiloxane, which means there are no unreacted double bonds, resulting in a higher proportion of siloxane bonds in the organic-inorganic hybrid material.

[0060] FIG. 12 shows an experimental setup 25 for measuring the transmittance of the synthesized organic-inorganic hybrid material. More specifically, FIG. 12(a) shows a photograph of the exterior of a washer 20 for containing the organic-inorganic hybrid material. The washer 20 has a hole diameter of 8 mm and a thickness of 1.5 mm. FIG. 12(b) shows a cross-sectional view of the experimental setup 25 for measuring the transmittance. The washer 20 is placed on a 430 μm-thick, double-sided polished sapphire substrate 21 (off-angle 0.1), and the synthesized organic-inorganic hybrid material 13a is filled inside the washer 20. The organic-inorganic hybrid material 13a contained in the washer 20 is uniformly (flattened) to a thickness of approximately 1.6 mm. In this way, transmittance measurements were performed using the experimental setup 25, which mimics the optical device 10.

[0061] Table 2 below shows the weights of the materials (PDMS, PDEOS) used in the synthesis and the silica content ("SiO2 (wt%)") for the measured samples S1 to S6 of the organic-inorganic hybrid material 13a.

[0062] [Table 2]

[0063] Each of Samples S1 to S6 includes two samples that were naturally cured at room temperature and two samples that were cured at 40°C for 12 hours. Additionally, one of Samples S1 to S6 includes two samples that were cured at 60°C for 12 hours.

[0064] The experimental procedure (procedure for curing by heating) is as follows.

[0065] (1) Fix the washer 20 to the sapphire substrate 21 with instant adhesive. (2) On a wafer heated on a hot plate, the organic-inorganic hybrid material 13a is dropped into the inside of the washer 20 using a dropper. (3) 12-hour curing (4) Measure the transmittance using a spectrophotometer with a φ2 mm probe light

[0066] Fig. 13A shows the results of measuring the transmittance of the synthesized organic-inorganic hybrid material 13a. More specifically, Fig. 13A(a) shows the weight / weight % of the materials used in the synthesis of samples S1 to S6, and Fig. 13A(b) shows the optical absorption spectra of samples S1 to S6 and sapphire (horizontal axis: wavelength (nm), vertical axis: transmittance (%)). The transmittance (%) is a value normalized by the transmittance at a sapphire thickness of 600 nm. The legend "S1a_40C" indicates sample "a" of sample S1, which was cured at 40°C. The same applies to the other samples.

[0067] As can be seen from Figure 13A, many samples exhibited high transmittance of approximately 80% at a wavelength of 265 nm. In particular, samples S4a_40C and S5a_40C tended to exhibit low absorption of light at a wavelength of 265 nm. The variation in transmittance is thought to be due to the non-uniformity of the sample (organic-inorganic hybrid material 13a) film thickness. Samples containing 10% or less silica nanoparticles exhibited absorption at wavelengths below 270 nm, while samples containing less than 40% silica nanoparticles exhibited degradation after 10 hours of UV irradiation at a wavelength of 265 nm and an energy of 1.5 mW. Increasing the silica nanoparticle content improved transmittance down to wavelengths below 250 nm and reduced UV degradation. In other words, organic-inorganic hybrid materials containing 40% or more silica nanoparticles and 60% or less polydimethylsiloxane exhibited reduced UV degradation and high UV transmittance.

[0068] 13B is a graph showing measurement results indicating the difference in transmittance of organic-inorganic hybrid material 13a depending on the curing temperature during synthesis. The graph shows the absorption spectra (horizontal axis: wavelength (nm), vertical axis: transmittance (%)) of sapphire, sample S3a (cured for 12 hours at 40°C), and sample S3b (cured for 12 hours at 60°C). As can be seen from the difference in absorption spectra between samples S3a and S3b, the absorption spectrum of organic-inorganic hybrid material 13a differs depending on the curing temperature during synthesis.

[0069] Next, an aging experiment was conducted in which the synthesized organic-inorganic hybrid material 13a was irradiated with deep ultraviolet light, and this experiment will be described. In this experiment, the light had a wavelength of 262 nm and was 2.9 mW / cm 2 The organic-inorganic hybrid material 13a was continuously irradiated with deep ultraviolet light having an output of 262 nm and 278 nm, and the time change in transmittance at two wavelengths of 262 nm and 278 nm was measured.

[0070] Figure 14 is a plot of the time change in transmittance at two wavelengths, 262 nm and 278 nm, for the synthesized organic-inorganic hybrid material 13a. That is, it shows the experimental results of the transmittance improvement step S30 in Figure 6. As shown in the figure, the organic-inorganic hybrid material 13a used in the experiment had a composition ratio (weight ratio of PDMS, SiO, and CFCHCH) of 49:33:18.

[0071] 14, it was found that the transmittance of the organic-inorganic hybrid material 13a increases when irradiated with deep ultraviolet light, and reaches a maximum value after about 80 hours. In other words, it was found that the optical properties of the organic-inorganic hybrid material 13a are improved by irradiating it with deep ultraviolet light.

[0072] Figure 15 is a hypothetical diagram of the mechanism by which transmittance is improved by irradiating deep-ultraviolet light onto organic-inorganic hybrid material 13a. As shown in Figure 15, the improvement in transmittance is presumably due to the fact that, when strong deep-ultraviolet light is irradiated onto organic-inorganic hybrid material 13a (Figure 15(a)), hydrogen is abstracted from the methyl groups of dimethylsiloxane (Figure 15(b)), and the resulting radicals are hydroxylated (Figure 15(d)) by coupling or oxidation reactions (Figure 15(c)), resulting in a decrease in the number of methyl groups.

[0073] As described above, the optical device 10 according to this embodiment includes an optical element (in this embodiment, an LED chip 12) that emits or receives ultraviolet light, and a resin member (in this embodiment, a resin lens 13) that covers the optical element, and the optical element includes a substrate 12a and a plurality of semiconductor layers 12b that are stacked on the substrate 12a, and the resin lens 13 is made of an organic-inorganic hybrid material that is a complex of silica nanoparticles and polydimethylsiloxane, and covers the optical element from the side of the substrate 12a, among the plurality of semiconductor layers 12b and the substrate 12a.

[0074] As a result, the resin lens 13 has high transmittance to ultraviolet light, a refractive index close to that of the substrate 12a of the optical element, and covers the optical element, thereby realizing an optical device 10 that can emit or receive ultraviolet light with high light extraction efficiency or light capture efficiency.

[0075] According to the embodiment, the optical device 10 has the characteristic of emitting ultraviolet light with an external quantum efficiency of 5% or more, and the optical device 10 has the characteristic of emitting ultraviolet light with an output power exceeding 100 mW.

[0076] Here, the organic-inorganic hybrid material preferably contains a fluoroalkyl group, which improves the transmittance of the resin lens 13.

[0077] Specifically, the organic-inorganic hybrid material is a compound containing a fluoroalkyl group, as exemplified by the above formula 1. The substrate 12a is, for example, sapphire or aluminum nitride. The semiconductor layers 12b include, for example, an AlN layer and an AlGaN layer.

[0078] Furthermore, the manufacturing method of the optical device 10 according to this embodiment includes a preparation step S10 of preparing an optical element that emits or receives ultraviolet light, and a resin member preparation step S200 of preparing a resin member that covers the optical element, wherein the optical element includes a substrate 12a and a plurality of semiconductor layers 12b stacked on the substrate 12a, and the resin member preparation step S200 includes a resin synthesis step S210 of synthesizing an organic-inorganic hybrid material by mixing at least silanol-terminated polydimethylsiloxane and polydiethoxysiloxane, and a sealing step S220 of hemispherically covering the optical element from the substrate 12a side with the synthesized organic-inorganic hybrid material, among the plurality of semiconductor layers 12b and the substrate 12a.

[0079] As a result, the produced resin lens 13 has high transmittance to ultraviolet light, a refractive index close to that of the substrate 12a of the optical element, and covers the optical element in a hemispherical shape, thereby realizing an optical device 10 that can emit or receive ultraviolet light with high light extraction efficiency or light capture efficiency.

[0080] In the resin synthesis step S210, it is preferable to mix a fluorine-containing silane coupling agent in addition to the silanol-terminated polydimethylsiloxane and polydiethoxysiloxane. For example, the fluorine-containing silane coupling agent is CF3-TMOS. This improves the transmittance of the resin lens 13.

[0081] In the resin synthesis step S210, a mixture of silanol-terminated polydimethylsiloxane, polydiethoxysiloxane, and a fluorine-containing silane coupling agent is preferably subjected to a sol-gel reaction using dibutyltin dilaurate as a catalyst. This allows for the synthesis of an organic-inorganic hybrid material, which is the material for the resin lens 13, by carrying out co-hydrolysis and condensation in a single reaction step known as the sol-gel reaction, a low-temperature glass production technology.

[0082] Furthermore, the method may further include a transmittance increasing step S30 of increasing the transmittance of the resin member by causing the optical device 10 to emit ultraviolet light, thereby increasing the transmittance of the resin member.

[0083] While the optical device and the manufacturing method of the optical device according to the present disclosure have been described above based on the embodiments and examples, the present disclosure is not limited to these embodiments and examples. As long as they do not deviate from the gist of the present disclosure, various modifications that a person skilled in the art may make to the embodiments and examples, and other forms constructed by combining some of the components or steps in the embodiments and examples, are also included within the scope of the present disclosure.

[0084] For example, in the above embodiment, the optical element is the LED chip 12 that emits ultraviolet light, but the present invention is not limited to this and may be a light receiving element that receives ultraviolet light.

[0085] Furthermore, the LED chip 12 and the wiring substrate 11 may be provided with a reflective layer such as an Al layer that reflects ultraviolet light emitted downward from the LED chip 12.

[0086] Furthermore, the organic-inorganic hybrid material that is the material of the resin lens 13 does not necessarily need to contain a fluoroalkyl group. Whether or not to add a fluoroalkyl group may be determined appropriately depending on the desired transmittance of the resin lens 13. [Industrial Applicability]

[0087] The optical device according to the present disclosure can be used as an optical device that emits ultraviolet light, for example, as an LED for sterilizing water or inactivating viruses in the air, and particularly as an optical device that can emit or receive ultraviolet light with high light extraction efficiency or light capture efficiency.

[0088] The present invention also encompasses the implementation of the presently disclosed organic-inorganic hybrid resin films, hybrid resin lenses, hybrid resin plates, etc., which have high deep UV transmittance. For example, applications are conceivable in fields where deep UV transmission is desired, such as greenhouse sheeting in agriculture and waterproofing films used in sterilization processes, including water treatment, in fresh food processing. [Explanation of symbols]

[0089] 10, 10a optical equipment 11 Wiring board 12 LED chips (optical elements) 12a board 12b Semiconductor layer 12c electrode 13 Resin lens 13a Organic-inorganic hybrid materials 20 washers 21 Sapphire substrate 25 Experimental Equipment

Claims

1. an optical element that emits or receives ultraviolet light; a resin member covering the optical element, The optical element is A substrate; a plurality of semiconductor layers formed by lamination on the substrate, The resin member is an organic-inorganic hybrid material that is a composite of silica nanoparticles and polydimethylsiloxane, covering the optical element from the substrate side of the plurality of semiconductor layers and the substrate; The organic-inorganic hybrid material is composed of three types of units, Si—CH ３ Organosilicon (a), Si—CH ２ CH ２ CF ３ The organosilicon (b) and silicon (c) are repeatedly bonded to each other, and the organic silicon (b) and silicon (c) are represented by the following chemical formula: 【Chemistry 1】 optical equipment.

2. The organic-inorganic hybrid material has a property that its transmittance increases when irradiated with deep ultraviolet light.

2. The optical device according to claim 1.

3. The organic-inorganic hybrid material is a composite containing 40% by weight or more of silica nanoparticles and 60% by weight or less of polydimethylsiloxane.

3. The optical device according to claim 1.

4. The organic-inorganic hybrid material is an organic-inorganic hybrid material that is a composite containing a fluoroalkyl group.

3. The optical device according to claim 1.

5. The substrate is sapphire or aluminum nitride.

3. The optical device according to claim 1.

6. The resin member has a lens function.

3. The optical device according to claim 1.

7. The optical device has a characteristic of emitting ultraviolet light with an external quantum efficiency of 5% or more.

3. The optical device according to claim 1.

8. The plurality of semiconductor layers include an AlN layer and an AlGaN layer.

3. The optical device according to claim 1.

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