Light-emitting device and method for manufacturing the same

Abstract

To provide a light-emitting device and the like with suppressed degradation of quantum dots.SOLUTION: A method for manufacturing a light-emitting device 100 including a light-emitting element 20 and quantum dots for converting a wavelength of light emitted by the light-emitting element 20 includes the steps of: preparing a base 10 and a light-emitting element 20 arranged on the base 10; forming a light reflection part 30 surrounding the light-emitting element 20 and including an inner surface and an upper surface; forming a first barrier layer 34 continuously covering a surface of the light-emitting element 20 and the inner surface and the upper surface of the light reflection part 30; forming a wavelength conversion part 40 embedding the light-emitting element 20 and including the quantum dots in a region surrounded by the inner surface of the light reflection part 30; and covering an upper surface of the wavelength conversion part 40 and the first barrier layer 34 provided on the upper surface of the light reflection part 30 with a second barrier layer 35.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a light-emitting device and a method for manufacturing the same. [Background technology]

[0002] Conventionally known light-emitting devices that emit white light include a light-emitting element that emits blue light, a green phosphor (or a yellow-green phosphor that emits yellow-green light) that absorbs a portion of the blue light emitted by the light-emitting element and emits green light, and a red phosphor that absorbs a portion of the blue light emitted by the light-emitting element and emits red light.

[0003] In recent years, light-emitting devices have been developed in which all or part of the phosphor is replaced with quantum dots (QDs). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2007-273498 [Overview of the project] [Problems that the invention aims to solve]

[0005] Quantum dots have a problem in that they degrade over time when exposed to oxygen and moisture, resulting in a decrease in wavelength conversion performance. One of the objectives of this disclosure is to provide a light-emitting device and a method for manufacturing the same that suppress the degradation of quantum dots. [Means for solving the problem]

[0006] A method for manufacturing a light-emitting device according to one embodiment of the present invention is a method for manufacturing a light-emitting device comprising a light-emitting element and a quantum dot that wavelength-converts light emitted by the light-emitting element, comprising the steps of: preparing a substrate and a light-emitting element disposed on the substrate; forming a light-reflecting portion that surrounds the light-emitting element and has an inner surface and an upper surface; forming a first barrier layer that continuously covers the surface of the light-emitting element and the inner surface and upper surface of the light-reflecting portion; forming a wavelength-converting portion including a quantum dot in which the light-emitting element is embedded within a region surrounded by the inner surface of the light-reflecting portion; and covering the upper surface of the wavelength-converting portion and the first barrier layer provided on the upper surface of the light-reflecting portion with a second barrier layer.

[0007] Furthermore, another embodiment of the present invention provides a light-emitting device comprising: a substrate; a light-emitting element disposed on the substrate; a light-reflecting portion surrounding the light-emitting element and having an inner surface and an upper surface; a first barrier layer continuously covering the surface of the light-emitting element and the inner surface and upper surface of the light-reflecting portion; a wavelength conversion portion including quantum dots disposed within a region surrounded by the inner surface of the light-reflecting portion; and a second barrier layer covering the upper surface of the wavelength conversion portion and the first barrier layer provided on the upper surface of the light-reflecting portion. [Effects of the Invention]

[0008] According to the light-emitting device and its manufacturing method according to one embodiment of the present invention, it is possible to provide a light-emitting device and its manufacturing method that suppress the degradation of quantum dots. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view of a light-emitting device according to an embodiment of the present invention. [Figure 2] This is an enlarged cross-sectional view of the light-emitting device shown in Figure 1. [Figure 3] This is a cross-sectional view showing the manufacturing process of a light-emitting device according to an embodiment of the present invention. [Figure 4] This is a cross-sectional view showing the manufacturing process of a light-emitting device according to an embodiment of the present invention. [Figure 5] This is a cross-sectional view showing the manufacturing process of a light-emitting device according to an embodiment of the present invention. [Figure 6] It is a cross-sectional view showing the manufacturing process of the light-emitting device according to an embodiment of the present invention. [Figure 7] It is a cross-sectional view showing the manufacturing process of the light-emitting device according to an embodiment of the present invention. [Figure 8] It is a cross-sectional view showing the manufacturing process of the light-emitting device according to an embodiment of the present invention. [Figure 9] It is a cross-sectional view showing the manufacturing process of the light-emitting device according to an embodiment of the present invention. [Figure 10] It is a cross-sectional view showing the light-emitting device according to the first modification example. [Figure 11] It is a cross-sectional view showing an example in which a color filter is provided in the light-emitting device of FIG. 10. [Figure 12] It is a cross-sectional view showing the manufacturing process of the light-emitting device according to the second modification example. [Figure 13] It is a cross-sectional view showing the manufacturing process of the light-emitting device according to the second modification example. [Figure 14] It is a cross-sectional view showing the manufacturing process of the light-emitting device according to the second modification example. [Figure 15] It is a cross-sectional view showing the light-emitting device according to the third modification example. [Figure 16] It is a cross-sectional view showing the light-emitting device according to the fourth modification example. [Figure 17] It is a cross-sectional view showing the manufacturing process of the light-emitting device according to another embodiment of the present invention. [Figure 18] It is a cross-sectional view showing the manufacturing process of the light-emitting device according to another embodiment of the present invention. [Figure 19] It is a graph showing the spectral emission luminance of the red quantum dots of the light-emitting device according to an example of the present invention. [Figure 20] It is a graph showing the spectral emission luminance of the green quantum dots of the light-emitting device according to an example of the present invention. [Figure 21] It is a graph showing the spectral emission luminance of the red quantum dots of the light-emitting device according to the comparative example. [Figure 22] [[ID=D50]]It is a graph showing the spectral emission luminance of the green quantum dots of the light-emitting device according to the comparative example. [Figure 23]This is an enlarged cross-sectional view of the main part of an image display device that uses an active matrix display. [Figure 24] This is a schematic block diagram of an image display device. [Figure 25] This is a schematic perspective view illustrating an image display device according to a modified example. [Modes for carrying out the invention]

[0010] The present invention will be described below with reference to the drawings. In the following description, terms indicating specific directions or positions (for example, "up," "down," and other terms including these) will be used as needed. The use of these terms is for the purpose of facilitating the understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms. Also, parts with the same reference numerals appearing in multiple drawings indicate the same or equivalent parts or components.

[0011] Furthermore, the embodiments described below illustrate specific examples of the technical concept of the present invention and do not limit the present invention to those described below. Also, the dimensions, materials, shapes, relative arrangements, etc., of the components described below are intended to be illustrative, and not to limit the scope of the present invention unless otherwise specified. Moreover, the content described in one embodiment or example is applicable to other embodiments and examples. Additionally, the size and positional relationships of the members shown in the drawings may be exaggerated for clarity. [Embodiment]

[0012] Figure 1 shows a cross-sectional view of a light-emitting device according to an embodiment. The light-emitting device 100 shown in this figure comprises a base 10, a light-emitting element 20 disposed on the base 10, a light-reflecting section 30 surrounding the light-emitting element 20, and a wavelength conversion section 40. (Base 10)

[0013] The substrate 10 is composed of a support substrate on which a light-emitting element 20, a light-reflecting part 30, etc., are mounted. Such a substrate 10 can be a rigid substrate such as a ceramic substrate or a SiC substrate, or a flexible substrate such as a printed circuit board. Using a printed circuit board is preferable because it allows for the fabrication of a flexible light-emitting device. (Light-emitting element 20)

[0014] The light-emitting element 20 is placed on the substrate 10. In the example shown in Figure 1, the light-emitting element 20 is positioned on the upper surface of the light-reflecting portion 30 provided on the substrate 10. In this example, there is one light-emitting element 20, but multiple light-emitting elements may be arranged.

[0015] Light-emitting elements such as LEDs and LDs can be suitably used for the light-emitting element 20. For LEDs, a semiconductor laminate equipped with a light-emitting part (hereinafter also simply referred to as "semiconductor laminate") can be used. The semiconductor laminate has light-emitting properties, and such a semiconductor laminate is used in which multiple semiconductor layers such as ZnS, SiC, GaN, GaP, InN, AlN, ZnSe, GaAsP, GaAlAs, InGaN, GaAlN, AlInGaP, AlInGaN, etc. are stacked on a substrate by liquid-phase growth, HVPE, or MOCVD, and a light-emitting layer is formed on one of the semiconductor layers. By selecting the material of the semiconductor layer and its mixed crystal degree, the emission wavelength of the light-emitting part can be selected in various ways from ultraviolet light to infrared light. In particular, when making a display device that can be suitably used outdoors, a semiconductor laminate capable of high-brightness light emission is required. Therefore, it is preferable to select a nitride semiconductor as the material for the light-emitting part that emits high-brightness green and blue light. For example, as the material for the light-emitting part, In X Al Y Ga 1-X-Y A value such as N(0≦X≦1, 0≦Y≦1, X+Y≦1) can be used. The light-emitting element 20 can be 1 to 2000 μm in size, and it is preferable to use one that is 1 to 50 μm in size. (Light reflecting part 30)

[0016] The light-reflecting portion 30 is a component for reflecting the light emitted by the light-emitting element 20. Such a light-reflecting portion 30 is arranged to surround the light-emitting element 20. By providing the light-reflecting portion 30 around the light-emitting element 20, leakage of light from the light-emitting element 20 in unintended directions is suppressed. This light-reflecting portion 30 can be made of a resin containing a light-reflective material such as TiO2.

[0017] The light-reflecting portion 30 has an inner surface and an upper surface. In the example shown in Figure 1, the region enclosed by the inner surface of the light-reflecting portion 30 is defined as a recess 33. A metal layer 36 is formed on the bottom surface of the recess 33, and the light-emitting element 20 is placed on the metal layer 36. The light-reflecting portion 30 consists of a planar base portion 31 provided on the upper surface of the substrate 10 and a side wall portion 32 provided on the base portion 31. The region enclosed by the side wall portion 32 on the base portion 31 becomes the recess 33. The base portion 31 and the side wall portion 32 may be provided as separate components or may be formed integrally. If provided as separate components, the side wall portion 32 may be formed from a white dry film or the like (details will be described later).

[0018] The metal layer 36 is connected to electrodes formed on the light-emitting element 20 via solder or the like. The metal layer 36 is also connected to external electrodes, and driving power is supplied to the light-emitting element 20 from the external electrodes through the metal layer 36. Such a metal layer 36 can be made of materials such as Cu or Au. (Wavelength conversion unit 40)

[0019] The wavelength conversion unit 40 receives light emitted by the light-emitting element 20 and converts its wavelength to a different wavelength. The wavelength conversion unit 40 includes wavelength conversion materials such as quantum dots (QDs) and phosphors. Quantum dots convert light to different wavelengths depending on their particle size. Such quantum dots have an average particle size of 10 nm or less, preferably 4 nm to 10 nm. Multiple types of quantum dots with different particle sizes may also be mixed. In the example in Figure 2, two types, first quantum dots 41 and second quantum dots 42, are mixed. Here, the first quantum dot 41 is a red quantum dot with an average particle size of 9 nm that receives blue light from the light-emitting element and converts it to red light, and the second quantum dot 42 is a green quantum dot with an average particle size of 5 nm that receives blue light from the light-emitting element and converts it to green light. The average particle size can be measured using a scanning transmission electron microscope HD-2000 manufactured by Hitachi High-Tech Corporation or the like.

[0020] Specific examples of quantum dots include phosphors with a perovskite structure, such as CdSe and InP, or semiconductor nanoparticles with a chalcopyrite structure. AgInSe2 is classified as a semiconductor nanoparticle with a chalcopyrite structure. Phosphors with a perovskite structure are expressed by the following equation. (M1A1) a M2 b X C

[0021] In the above formula, A1 represents one or more organic cations selected from the group consisting of ammonium, formamidinium, guanidium, imidazolium, pyridinium, pyrrolidinium, and protonated thiourea; M1 represents one or more alkali metal cations selected from Cs, Rb, K, Na, and Li; M2 represents one or more metal cations selected from the group consisting of Ge, Sn, Pb, Sb, Te, and Bi; X represents one or more anions selected from the group consisting of chloride ions, bromide ions, iodide ions, cyanide ions, thiocyanate ions, isothiocyanate ions, and sulfide ions; a represents 1 to 4; b represents 1 to 2; and c represents 3 to 9.

[0022] Further, semiconductor nanoparticles having a chalcopyrite structure and emitting green light are represented, for example, by the following formula. (Ag p M a (1-p) ) q In r Ga (1-r) S (q+3) / 2 Here, p, q, and r satisfy 0 < p ≤ 1, 0.20 < q ≤ 1.2, and 0 < r < 1. M a represents an alkali metal.

[0023] The semiconductor nanoparticles (first semiconductor) represented by the above formula may have a second semiconductor containing Ga and S disposed on its surface. The semiconductor nanoparticles exhibit band-edge emission having an emission peak wavelength in the wavelength range of 475 nm or more and 560 nm or less upon irradiation with light having a wavelength of 365 nm. The ratio of the number of In atoms to the total number of In and Ga atoms in the first semiconductor (In / (In + Ga)) is, for example, 0.01 or more and less than 1, preferably 0.1 or more and 0.99 or less. Also, the ratio of the number of Ag atoms to the total number of In and Ga atoms (Ag / (In + Ga)) is, for example, 0.3 or more and 1.2 or less, preferably 0.5 or more and 1.1 or less. The ratio of the number of S atoms to the total number of Ag, In, and Ga atoms (S / (Ag + In + Ga)) is, for example, 0.8 or more and 1.5 or less, preferably 0.9 or more and 1.2 or less. The semiconductor nanoparticles have a full width at half maximum in their emission spectrum of, for example, 45 nm or less, preferably 40 nm or less, or 35 nm or less. The lower limit of the full width at half maximum is preferably 15 nm or more. Also, the emission lifetime of the main component (band-edge emission) is preferably 200 ns or less.

[0024] Furthermore, semiconductor nanoparticles having a chalcopyrite structure and emitting red light are represented, for example, by the following formula. (Ag p Cu (1-p) ) q In r Ga (1-r) S (q+3) / 2 Here, p, q, and r satisfy 0 < p < 1, 0.20 < q ≤ 1.2, and 0 < r < 1.

[0025] In the semiconductor nanoparticles (first semiconductor) represented by the above formula, a second semiconductor containing Ga and S may be disposed on its surface. The semiconductor nanoparticles exhibit band-edge emission having an emission peak wavelength in the wavelength range of 600 nm or more and 680 nm or less upon irradiation with light having a wavelength of 365 nm. The ratio of the number of moles of Cu to the total number of moles of Cu and Ag in the composition of the first semiconductor (Cu / (Cu + Ag)) is 0.01 or more and less than 1.0, preferably 0.03 or more and 0.99 or less, and more preferably 0.05 or more and 0.5 or less. For example, the ratio of the total number of moles of Cu and Ag to the total number of moles of Cu, Ag, In, and Ga in the composition of the first semiconductor ((Cu + Ag) / (Cu + Ag + In + Ga)) is 0.1 or more and less than 1.0, preferably 0.2 or more and 0.99 or less. The ratio of the number of atoms of In to the total number of atoms of In and Ga in the first semiconductor (In / (In + Ga)) is, for example, 0.01 or more and less than 1, preferably 0.1 or more and 0.99 or less. Also, the ratio of the number of atoms of Ag to the total number of atoms of In and Ga (Ag / (In + Ga)) is, for example, 0.1 or more and 1.2 or less, preferably 0.2 or more and 1.1 or less. Also, the ratio of the total number of atoms of Ag and Cu to the total number of atoms of In and Ga ((Ag + Cu) / (In + Ga)) is, for example, 0.1 or more and 1.2 or less, preferably 0.2 or more and 1.0 or less. The ratio of the number of atoms of S to the total number of atoms of Ag, In, and Ga (S / (Ag + In + Ga)) is, for example, 0.8 or more and 1.5 or less, preferably 0.9 or more and 1.2 or less. The ratio of the number of atoms of S to the total number of atoms of Ag, Cu, In, and Ga (S / (Ag + Cu + In + Ga)) is, for example, 0.8 or more and 1.5 or less, preferably 0.9 or more and 1.2 or less. Also, the full width at half maximum in the emission spectrum of the semiconductor nanoparticles is, for example, 70 nm or less, preferably 65 nm or less, or 60 nm or less. The lower limit of the full width at half maximum is preferably 15 nm or more. Also, the emission lifetime of the main component (band-edge emission) is preferably 200 ns or less.

[0026] The wavelength conversion section 40 is positioned at least on the light-emitting element 20 within the region enclosed by the inner surface of the light-reflecting section 30. In the example shown in Figure 1, the wavelength conversion section 40 is filled into the recess 33 of the light-reflecting section 30, thereby embedding the light-emitting element 20. It is also preferable that the upper surface of the wavelength conversion section 40 and the upper surface of the light-reflecting section 30 be formed on the same plane. This allows for a constant film thickness when a color filter 50 is provided on the upper surface of the wavelength conversion section 40, resulting in the advantage of uniformly exhibiting a filtering effect. Furthermore, since the second barrier layer, which will be described later, can be provided flat, the gas barrier properties are improved. (First barrier layer 34)

[0027] Furthermore, the light-emitting device 100 includes a first barrier layer 34 and a second barrier layer 35 that cover part or all of its surface. The first barrier layer 34 is made of a material having gas barrier properties. It can also be made to have moisture barrier properties. The first barrier layer 34 continuously covers the surface of the light-emitting element 20 and the inner and upper surfaces of the light-reflecting part 30. This prevents oxygen and moisture contained in the outside air from penetrating the wavelength conversion part 40 through the light-reflecting part 30 and degrading the quantum dots contained in the wavelength conversion part 40. The oxygen permeability of the first barrier layer 34 is 1 × 10⁻¹⁶. -2 g / m 2 It is preferable that the oxygen permeability be less than or equal to / day. The oxygen permeability can be measured by the differential pressure method (JIS K 7126-1). In such a first barrier layer 34, AlN a AlO b SiO c SiN d The following can be used: (1 / 3≦a≦1, 0.5≦b≦1.5, 0.5≦c≦2, 1 / 3≦d≦4 / 3), etc. Furthermore, the thickness of the first barrier layer 34 is preferably 100nm to 200nm on average, but this is not limited to this. The average thickness can be measured using a stylus-type profiling system such as the Dektak XTL manufactured by BRUKER. (Second barrier layer 35)

[0028] The second barrier layer 35 continuously covers the upper surface of the wavelength conversion section 40 and the region of the first barrier layer 34 that is located on the upper surface of the light reflection section 30. The second barrier layer 35 is also made of a material having gas barrier properties, such as AlN. a AlO b SiO c SiN d (1 / 3≦a≦1, 0.5≦b≦1.5, 0.5≦c≦2, 1 / 3≦d≦4 / 3), etc., can be used. The thickness of the second barrier layer 35 is preferably 100nm to 200nm on average, but is not limited to this. Preferably, the first barrier layer 34 and the second barrier layer 35 are made of the same material. It is also preferable to make the thickness of the first barrier layer 34 the same as the thickness of the second barrier layer 35, or to make the first barrier layer 34 thicker than the second barrier layer 35. This makes it easier to provide the first barrier layer 34 on the inner surface of the light reflection part 30, and an effect of suppressing the deterioration of the wavelength conversion part 40 can be obtained. The first barrier layer 34 and the second barrier layer 35 can also be made into a multilayer structure. By making it into a multilayer structure, it is possible to avoid the occurrence of localized deterioration of the gas barrier properties caused by pinholes or foreign matter that occur during the deposition of the gas barrier film.

[0029] As shown in the enlarged cross-sectional view of Figure 2, by covering the wavelength conversion section 40 containing quantum dots with a first barrier layer 34 and a second barrier layer 35, and by double-covering the upper surface of the light-reflecting section 30 located around the recess 33 with the first barrier layer 34 and the second barrier layer 35, the gas barrier properties for quantum dots can be enhanced. This makes it possible to improve the reliability of quantum dots, which are susceptible to degradation by outside air and moisture. (Color filter 50)

[0030] A color filter 50 may be provided on the second barrier layer 35. The color filter 50 is a component for absorbing light emitted from the light-emitting element 20 that was not absorbed by the wavelength conversion unit 40. Pigment-based color resists and the like can be used for such a color filter 50. [Manufacturing method for light-emitting devices]

[0031] The manufacturing method of the above-described light-emitting device will be explained with reference to Figures 3 to 9. Here, we will explain a method for manufacturing a light-emitting device that emits white light by mixing colors, by combining a light-emitting element 20 that emits blue light with a wavelength conversion unit 40 that includes quantum dots that emit red and green light in response to the blue light from the light-emitting element 20.

[0032] First, a substrate 10 and a light-emitting element 20 placed on the substrate 10 are prepared, and a light-reflecting portion 30 is formed to surround the light-emitting element 20. For example, a printed circuit board with a thickness of 100 μm is prepared as the substrate 10, and a silicone resin mixed with TiO2 particles is applied to its upper surface as the base portion 31 of the light-reflecting portion 30 and cured. Furthermore, a metal layer 36 is formed on a part of the base portion 31 by Cu plating, and a blue LED is mounted on this metal layer 36 as the light-emitting element 20. In this state, as shown in Figure 3, the area on the upper surface of the base portion 31 where the side wall portion 32 is not to be formed is protected with a resist 60. The resist 60 can be an acrylic resin-based photoresist or the like. Then, as shown in Figure 4, a resin to form the side wall portion 32 of the light-reflecting portion 30 is applied from the top of the resist 60. Here, a silicone resin mixed with TiO2 particles, the same as the base portion 31, is applied and cured. Then, as shown in Figure 5, the surface of the silicone resin is cut to expose the resist 60. Furthermore, as shown in Figure 6, the resist 60 is removed by reactive ion etching (RIE) to form the side wall portion 32.

[0033] Next, as shown in Figure 7, the first barrier layer 34 is formed to continuously cover the upper and inner surfaces of the light-reflecting portion 30 and the surface of the light-emitting element 20. Here, a layer composed of Al2O3, SiO2, SiN, etc., is formed by sputtering with an average film thickness of 150 nm. By using sputtering, the film thickness of the deposited first barrier layer 34 can be precisely controlled.

[0034] Furthermore, after coating with a first barrier layer 34, a wavelength conversion section 40 is formed in the recess 33. Here, as shown in Figure 8, a wavelength conversion member containing green quantum dots with an average particle size of 5 nm that convert the blue light from the light-emitting element 20 to green light, and red quantum dots with an average particle size of 9 nm that convert the blue light to red light, is filled into the recess 33 by photolithography and cured. This provides the advantage of being able to form the wavelength conversion member containing quantum dots with an accurate pattern and film thickness. Note that the method of forming the wavelength conversion section is not limited to photolithography; for example, an inkjet method in which the wavelength conversion member containing quantum dots is sprayed and applied from an inkjet nozzle can also be used. This provides the advantage of being able to fill only the appropriate amount of wavelength conversion member into the recess 33, avoiding material waste and efficiently filling the wavelength conversion member in the appropriate place. Thus, the inkjet method is advantageous in terms of cost and efficiency.

[0035] Next, a second barrier layer 35 is provided. Here, as shown in Figure 9, a layer composed of Al2O3, SiO2, SiN, etc., is formed by sputtering with an average film thickness of 150 nm.

[0036] Finally, a color filter 50 is formed on the second barrier layer 35. Here, a pigment-based color resist is applied as the color filter 50 to the recess 33 of the light-reflecting portion 30 and the upper surface of the light-reflecting portion 30 located around it. In this way, the light-emitting device 100 shown in Figure 1 is obtained.

[0037] Furthermore, color filters are not limited to flat plates; they may also be formed in a lens shape. Lens-shaped color filters can be formed by patterning a negative-type photoresist material containing dispersed pigments into a lens shape using photolithography. [First variation]

[0038] Furthermore, in the example shown in Figure 1, a light-emitting device 100 was described in which a blue light-emitting diode is used as the light-emitting element 20, and a first quantum dot 41, which is a red quantum dot that receives the blue light from the light-emitting element 20 and converts it to red light, is combined with a second quantum dot 42, which is a green quantum dot that also receives the blue light and converts it to green light, and the blue light from the light-emitting element 20, the red light from the first quantum dot 41 and the green light from the second quantum dot 42 are mixed to emit white light. However, the present invention can also be applied to light-emitting devices with other combinations. For example, as a first modified example, as shown in the cross-sectional view of Figure 10, three blue light-emitting elements 20 are prepared: a first light-emitting element 20a, a second light-emitting element 20b, and a third light-emitting element 20c. The first light-emitting element 20a, the second light-emitting element 20b, and the third light-emitting element 20c can all be the same type of blue light-emitting diode. Then, a first light-emitting region 81 is formed by arranging the first quantum dot 41a, which is a red quantum dot that receives the blue light and converts it to red light, around the first light-emitting element 20a. On the other hand, a second light-emitting region 82 is formed by arranging a second quantum dot 42b, which is a green quantum dot that receives blue light and converts it into green light, around the second light-emitting region 20b. A first barrier layer 34 and a second barrier layer 35 are provided in the first light-emitting region 81 and the second light-emitting region 82, respectively. Meanwhile, a third light-emitting region 83 is formed by arranging a third light-emitting region 20c. Since no quantum dots are provided in the third light-emitting region 83, the first barrier layer 34 and the second barrier layer 35 do not need to be provided. The light-emitting device 100B configured in this way can emit white light by mixing the red light from the first light-emitting region 81, the green light from the second light-emitting region 82, and the blue light from the third light-emitting region 83.

[0039] In addition, a color filter may also be provided in a light-emitting device having multiple light-emitting regions. An example of this is shown in the cross-sectional view of Figure 11. As shown in this figure, a color filter 50B made of a negative-type photoresist material in which pigments are dispersed can be applied to the upper surface of each light-emitting region and formed into a lens shape by photolithography. [Second variation]

[0040] Furthermore, the light-emitting device may include a black matrix. The black matrix is ​​a light-shielding component that improves visibility by covering the area around the light-emitting region with black. Such a black matrix can be made of a resin material or the like that contains a pigment such as black, which acts as a light-shielding material, to provide light-shielding properties. In addition to resin, the black matrix can also be made of metal.

[0041] As an example of a method for manufacturing a light-emitting device equipped with a black matrix, the procedure for constructing a modified light-emitting device according to Modification 2, in which a black mask is added to the light-emitting device of Figure 10, will be explained based on Figures 12 to 14. First, as shown in Figure 12, a first light-emitting region 81 in which the first light-emitting element 20a is placed, a second light-emitting region 82 in which the second light-emitting element 20b is placed, and a third light-emitting region 83 in which the third light-emitting element 20c is placed are formed. Here, since a side wall portion 32 is formed in the light-reflecting portion 30, the same procedure as in Figure 6 described above can be used.

[0042] Next, a black matrix 85 is formed on the upper surface of each side wall portion 32 in Figure 12. Here, a light-shielding resin constituting the black matrix 85, such as a negative-type photoresist material in which black pigment is dispersed, is applied using a technique such as photolithography. The black matrix 85 is provided to have a thickness of 1 μm to 10 μm.

[0043] In this state, the first barrier layer 34 and the second barrier layer 35 are formed on the first light-emitting region 81 and the second light-emitting region 82, respectively, using the same procedure as described in Figures 7 to 9 above. Furthermore, color filters are formed on each light-emitting region as needed. In the example in Figure 14, flat color filters 50C are formed on the first light-emitting region 81 and the second light-emitting region 82, respectively. In this way, a light-emitting device 100C equipped with a black matrix 85 can be obtained. [Third and fourth variations]

[0044] In the first and second modified examples described above, an example of a light-emitting device was explained in which only a blue light-emitting diode is used as the light-emitting element, and white light is obtained by mixing the red light from the first light-emitting region 81, the green light from the second light-emitting region 82, and the blue light from the third light-emitting region 83. However, the present invention is not limited to a configuration using only one type of light-emitting element, and a light-emitting device may be configured with multiple light-emitting elements that emit light of different colors. For example, as shown in Figure 15, in the light-emitting device 100D according to the third modified example, instead of arranging a green quantum dot that receives blue light and converts it to green light as used in Figure 10, etc., a second light-emitting element 20b' that emits green light may be arranged in the second light-emitting region 82. Alternatively, as shown in Figure 16, in the fourth modified light-emitting device 100E, instead of arranging the first light-emitting region 81 with a first light-emitting element 20a, which is a blue light-emitting diode used in Figure 15 etc., and a red quantum dot that receives this blue light and converts it into red light, the first light-emitting region 81 may be configured with a first light-emitting element 20a' that emits green light and a first quantum dot 41a' that receives this green light and converts it into red light. The first light-emitting element 20a' can be the same type of green light-emitting diode as the second light-emitting element 20b' arranged in the second light-emitting region 82. Furthermore, a color filter 50D may be added to the first light-emitting region 81. Both the light-emitting device 100D according to the third modified example and the light-emitting device 100E according to the fourth modified example can emit white light by mixing the red light from the first light-emitting region 81, the green light from the second light-emitting region 82, and the blue light from the third light-emitting region 83.

[0045] In the above example, a method for forming the side wall portion 32 using a resist has been described. However, the present invention is not limited to the above method for manufacturing the light-emitting device, and other methods can be used as appropriate. For example, the side wall portion may be formed using a white dry film as described above. Here, an example of forming the side wall portion using a white dry film will be described with reference to Figures 17 to 18.

[0046] First, prepare the substrate 10 and the light-emitting element 20. Next, form the base portion 31 of the light-reflecting portion 30 on the upper surface of the substrate 10. Then, form a metal layer 36 on a part of the base portion 31 and mount the light-emitting element 20 on this metal layer 36. Up to this point, the procedure can be the same as the method described above.

[0047] Next, as shown in Figure 17, a white dry film 70 is applied to the entire upper surface of the base portion 31. Such a white dry film 70 can be a negative-type photoresist material such as an acrylate resin containing a light-reflective material such as titanium dioxide. Photolithography is performed in this state and the film is developed to remove the unnecessary parts of the white dry film 70. Here, as shown in Figure 18, the area that does not form the side wall portion 32 is removed, and the remaining white dry film 70 becomes the side wall portion 32. Subsequently, the first barrier layer 34 and the second barrier layer 35 are provided in the same procedure as described in Figures 7 to 9 above. In this way, the light-emitting device 100 shown in Figure 1 is obtained. [Examples]

[0048] As described above, a light-emitting device having a first barrier layer and a second barrier layer was fabricated as an example, and a light-emitting device without the first and second barrier layers was fabricated as a comparative example, and the characteristics of both were compared. Here, the spectral radiance of red quantum dots and green quantum dots of the light-emitting devices according to the example and comparative example were measured immediately after fabrication and after being left at room temperature (approximately 20°C) for 10 days (240 hours), using a 2D spectroradiometer SR-5100HM manufactured by Topcon Techno House Co., Ltd., with the XYZ filter method. The measurement results are shown in the graphs in Figures 19 to 22. In these figures, Figures 19 and 20 show the measurement results of the light-emitting device according to the example, and Figures 21 and 22 show the measurement results of the light-emitting device according to the comparative example. Also, Figures 19 and 21 show the spectral radiance of red quantum dots, and Figures 20 and 22 show the spectral radiance of green quantum dots, respectively. Furthermore, in each figure, the waveform in the initial state immediately after the fabrication of the light-emitting device is shown with a solid line, and the waveform after 10 days is shown with a dashed line. As shown in these figures, in the comparative example, a significant decrease in spectral radiance was observed for both the red and green quantum dots, whereas in the example, a similar level of spectral radiance was maintained, confirming that the degradation suppression effect of the quantum dots was achieved by providing the first and second barrier layers. [Examples of application]

[0049] The structure disclosed in this invention can be applied to passive matrix arrays and active matrix array displays that display images. As an example of such a light-emitting device, Figure 23 shows an enlarged cross-sectional view of the main part of an image display device that is an active matrix display. The image display device 200 shown in this figure comprises a substrate 210, a light-emitting element 220 disposed on the substrate 210, a light-reflecting section 230 surrounding the light-emitting element 220, a wavelength conversion section 240, and a color filter 250. The surface of the light-emitting element 220 and the inner and upper surfaces of the light-reflecting section 230 are continuously covered with a first barrier layer 234. The upper surface of the wavelength conversion section 240 and the region of the first barrier layer 234 provided on the upper surface of the light-reflecting section 230 are continuously covered with a second barrier layer 235. Furthermore, the wavelength conversion section 240 contains a mixture of first quantum dots 241 and second quantum dots 242.

[0050] Here, as shown in Figure 23, each pixel contains both a first quantum dot 241 and a second quantum dot 242, resulting in white light produced by mixing the blue light emitted by the light-emitting element 220, the red wavelength converted output light from the first quantum dot 241, and the green wavelength converted output light from the second quantum dot 242. By arbitrarily providing a color filter that transmits blue light, a color filter that transmits red light, and a color filter that transmits green light, blue, red, and green subpixels can be created, as will be described later. As mentioned above, by further providing a black matrix between the color filters 50, ambient light reflection can be suppressed and ambient light visibility can be improved.

[0051] The substrate 210 includes a circuit board 211, an intermediate layer 212, an interlayer insulating film 213, a planarization film 214, and a gate insulating film 216. The circuit board 211 is a Si circuit board made of Si. A transistor 215 is provided on a part of the Si circuit board. The transistor 215 is electrically connected to the metal layer 236 via through-holes or through-electrodes. On the other hand, an interlayer insulating film 213 is interposed in the intermediate layer 212 to provide electrical insulation. Note that instead of a Si circuit board with transistors 215, the circuit board 211 may be a glass or resin substrate with low-temperature polycrystalline Si transistors.

[0052] A schematic block diagram of such an image display device 200 is shown in Figure 24. The image display device 200 shown in this figure includes a display area 2. Subpixels 202 are arranged in the display area 2. The subpixels 202 are arranged, for example, in a grid pattern. For example, n subpixels 202 are arranged along the X axis and m subpixels 202 are arranged along the Y axis.

[0053] Pixel 201 contains multiple subpixels 202 that emit light of different colors. Subpixel 202R emits red light. Subpixel 202G emits green light. Subpixel 202B emits blue light. The emission color and brightness of a single pixel 201 are determined by the emission of the three types of subpixels 202R, 202G, and 202B at the desired brightness.

[0054] A single pixel 201 contains three subpixels 202R, 202G, and 202B, which are arranged linearly along the X-axis, for example, as shown in Figure 24. Each pixel 201 may have subpixels of the same color arranged in the same column, or it may have subpixels of different colors arranged in each column, as in this example.

[0055] The image display device 200 further includes a power line 3 and a ground line 4. The power line 3 and ground line 4 are laid out in a grid pattern along the arrangement of subpixels 202. The power line 3 and ground line 4 are electrically connected to each subpixel 202 and supply power to each subpixel 202 from a DC power supply connected between the power terminal 3a and the GND terminal 4a. The power terminal 3a and the GND terminal 4a are provided at the ends of the power line 3 and the ground line 4, respectively, and are connected to a DC power supply circuit provided outside the display area 2. A positive voltage is supplied to the power terminal 3a with reference to the GND terminal 4a.

[0056] The image display device 200 further includes scan lines 6 and signal lines 8. The scan lines 6 are laid out in a direction parallel to the X-axis; that is, the scan lines 6 are laid out along the row-direction arrangement of the subpixels 202. The signal lines 8 are laid out in a direction parallel to the Y-axis; that is, the signal lines 8 are laid out along the column-direction arrangement of the subpixels 202.

[0057] The image display device 200 further includes a row selection circuit 5 and a signal voltage output circuit 7. The row selection circuit 5 and the signal voltage output circuit 7 are provided along the outer edge of the display area 2. The row selection circuit 5 is provided along the Y-axis direction of the outer edge of the display area 2. The row selection circuit 5 is electrically connected to the subpixels 202 of each column via scan lines 6 and supplies a selection signal to each subpixel 202.

[0058] The signal voltage output circuit 7 is provided along the X-axis direction of the outer edge of the display area 2. The signal voltage output circuit 7 is electrically connected to the subpixels 202 of each row via signal lines 8 and supplies a signal voltage to each subpixel 202.

[0059] The subpixel 202 includes a light-emitting element 220, a selection transistor 224, a drive transistor 226, and a capacitor 228. In Figure 24, the selection transistor 224 may be labeled T1, the drive transistor 226 may be labeled T2, and the capacitor 228 may be labeled Cm.

[0060] The light-emitting element 220 is connected in series with the drive transistor 226. In this embodiment, the drive transistor 226 is a p-channel TFT, and the anode electrode of the light-emitting element 220 is connected to the drain electrode of the drive transistor 226. The main electrodes of the drive transistor 226 and the selection transistor 224 are the drain electrode and the source electrode. The anode electrode of the light-emitting element 220 is connected to the p-type semiconductor layer of the semiconductor stack. The cathode electrode of the light-emitting element 220 is connected to the n-type semiconductor layer of the semiconductor stack. The series circuit of the light-emitting element 220 and the drive transistor 226 is connected between the power line 3 and the ground line 4. The drive transistor 226 corresponds to the transistor 215 in Figure 23, and the light-emitting element 220 corresponds to the light-emitting element 222 in Figure 24. The current flowing through the light-emitting element 222 is determined by the voltage applied between the gate and source of the drive transistor 226, and the light-emitting element 222 emits light with a brightness corresponding to the current flowing through it.

[0061] The selection transistor 224 is connected to the gate electrode of the drive transistor 226 and the signal line 8 via its main electrode. The gate electrode of the selection transistor 224 is connected to the scan line 6. A capacitor 228 is connected to the gate electrode of the drive transistor 226 and the power line 3.

[0062] The row selection circuit 5 selects one row from an array of m rows of subpixels 202 and supplies a selection signal to the scan line 6. The signal voltage output circuit 7 supplies a signal voltage with the required analog voltage value to each subpixel 202 of the selected row. The signal voltage is applied between the gate and source of the drive transistor 226 of the subpixels 202 of the selected row. The signal voltage is held by the capacitor 228. The drive transistor 226 flows a current corresponding to the signal voltage through the light-emitting element 220. The light-emitting element 220 emits light with a brightness corresponding to the current flowing through it.

[0063] The row selection circuit 5 sequentially switches the row to be selected and supplies a selection signal. In other words, the row selection circuit 5 scans the rows in which the subpixels 202 are arranged. A current corresponding to the signal voltage flows through the light-emitting element 220 of the sequentially scanned subpixels 202, causing them to emit light. The brightness of the subpixels 202 is determined by the current flowing through the light-emitting element 220. The subpixels 202 emit light in gradations based on the determined brightness, and an image is displayed in the display area 2.

[0064] In the above application example, a low-cost structure is disclosed in which the wavelength conversion unit 240 can be formed collectively by providing the same wavelength conversion unit 240 for each subpixel to generate white light. However, the wavelength conversion unit 240 can also have different structures for each blue, red, and green subpixel. In this case, the blue subpixel will not have a wavelength conversion function, the red subpixel will have a red wavelength conversion function, and the green subpixel will have a green wavelength conversion function. In such a case, blue light emission can be efficiently emitted to the outside, thus reducing power consumption during light emission. [Differentiation]

[0065] The image display device may also be constructed by stacking individually configured plate-shaped or layered members. An example of this is shown in Figure 25. In the image display device 300 shown in this figure, a plate-shaped or layered side wall portion 330 having a large number of light-emitting elements 320 is superimposed on a base portion 314, which is also a planarization film on a circuit layer 310. Multiple recesses are provided in the side wall portion 330, and the light-emitting elements 320 are embedded in each recess. A wavelength conversion section sealed by a first barrier layer and a second barrier layer is also provided in the recess. In addition, a color filter is provided at a position corresponding to each recess on the side wall portion 330. Recesses are formed in the circuit layer 310 and the base portion 314 at positions corresponding to each light-emitting element 320, and connection terminals corresponding to each light-emitting element 320 are provided inside the recesses.

[0066] By stacking the circuit layer 310 and the side wall portion 330 in this manner, the image display device 300 can treat the circuit layer 310 and the side wall portion 330, which includes numerous light-emitting elements 320 and a wavelength conversion unit, as independent components. This improves yield and reduces costs. This is because the circuit layer 310 and the side wall portion 330 can be individually inspected for defects, and after removing and repairing defective parts, the circuit layer 310 and the side wall portion 330 can be stacked. [Industrial applicability]

[0067] The light-emitting device and its manufacturing method of the present invention can be suitably used, for example, in large displays, smartphones, tablets, medium-sized monitors for in-vehicle use, or small screens such as HMDs and smart glasses screens. [Explanation of Symbols]

[0068] 100, 100B, 100C, 100D, 100E… Light-emitting devices 200, 300... Image display devices 2...Display area 3…power line; 3a…power terminal 4…Ground wire; 4a…GND terminal 5... Row selection circuit 6…Scan lines 7...Signal voltage output circuit 8... Signal wire 10, 210...Base 20, 220, 222, 320… light-emitting elements 20a, 20a'...First light-emitting element 20b, 20b'... Second light-emitting element 20c...Third light-emitting element 30, 230...Light reflecting part 31…Substrate 32... Side wall section 33…recess 34, 234... First barrier layer 35, 235... Second barrier layer 36, 236...metal layer 40, 240... Wavelength conversion section 41, 41a, 41a', 241… First quantum dots 42, 42a, 242… Second quantum dots 50, 50B, 50C, 50D, 250… Color filters 60... Resist 70…White dry film 81...First emission region 82...Second emission region 83...Third emission region 85... Black Matrix 201... pixels 202, 202R, 202G, 202B… subpixels 211... Circuit board 212…Middle class 213...Interlayer insulating film 214...Planarization film 215... Transistor 216... Gate insulating film 224...Selection transistor 226…Driver transistor 228…Capacitor 310...Circuit layer 314... Substrate 330... Side wall section

Claims

1. A method for manufacturing a light-emitting device comprising a light-emitting element and a quantum dot that wavelength-converts the light emitted by the light-emitting element, A step of preparing a substrate and the light-emitting element arranged on the substrate, A step of forming a light-reflecting portion that surrounds the light-emitting element and has an inner surface and an upper surface, A step of forming a first barrier layer that continuously covers the surface of the light-emitting element and the inner and upper surfaces of the light-reflecting portion, A step of forming a wavelength conversion section including quantum dots, in which the light-emitting elements are embedded within a region surrounded by the inner surface of the light-reflecting section, A step of covering the upper surface of the wavelength conversion section and the first barrier layer provided on the upper surface of the light reflection section with a second barrier layer that is thinner than the first barrier layer, A method for manufacturing a light-emitting device that includes [a specific component].

2. A method for manufacturing a light-emitting device according to claim 1, further, A method for manufacturing a light-emitting device, comprising the step of arranging a color filter on the second barrier layer.

3. A method for manufacturing a light-emitting device according to claim 1 or 2, A method for manufacturing a light-emitting device, wherein the first barrier layer and the second barrier layer are made of the same material.

4. A method for manufacturing a light-emitting device according to any one of claims 1 to 3, A method for manufacturing a light-emitting device, wherein the upper surface of the wavelength conversion section and the upper surface of the light reflection section are formed on the same plane.

5. A method for manufacturing a light-emitting device according to any one of claims 1 to 4, A method for manufacturing a light-emitting device, wherein the step of forming the wavelength conversion section includes forming the wavelength conversion member containing the quantum dots by photolithography.

6. A method for manufacturing a light-emitting device according to any one of claims 1 to 4, A method for manufacturing a light-emitting device, comprising the step of forming the wavelength conversion section by spraying and coating the wavelength conversion member containing the quantum dots from an inkjet nozzle.

7. A method for manufacturing a light-emitting device according to any one of claims 1 to 6, A method for manufacturing a light-emitting device, wherein the first barrier layer is formed by sputtering in the step of forming the first barrier layer.

8. A method for manufacturing a light-emitting device according to any one of claims 1 to 7, A method for manufacturing a light-emitting device, wherein the film thickness of the first barrier layer and / or the average film thickness of the second barrier layer is 100 nm to 200 nm.

9. A method for manufacturing a light-emitting device according to any one of claims 1 to 8, The first barrier layer and / or the second barrier layer are made of AlN a AlO b SiO c SiN d A method for manufacturing a light-emitting device composed of any of the following: (1 / 3 ≤ a ≤ 1, 0.5 ≤ b ≤ 1.5, 0.5 ≤ c ≤ 2, 1 / 3 ≤ d ≤ 4 / 3).

10. A method for manufacturing a light-emitting device according to any one of claims 1 to 9, The oxygen permeability of the first barrier layer and / or the second barrier layer is 1 × 10 -2 g / m 2 A method for manufacturing a light-emitting device that is less than or equal to / day.

11. Substrate and, A light-emitting element arranged on the substrate, A light-reflecting portion surrounds the light-emitting element and has an inner surface and an upper surface, A first barrier layer continuously covers the surface of the light-emitting element and the inner and upper surfaces of the light-reflecting portion. A wavelength conversion unit including quantum dots is arranged within the region surrounded by the inner surface of the light-reflecting portion, A second barrier layer covers the upper surface of the wavelength conversion section and the first barrier layer provided on the upper surface of the light reflection section. Equipped with, A light-emitting device wherein the thickness of the first barrier layer is greater than the thickness of the second barrier layer.

12. A light-emitting device according to claim 11, further A light-emitting device comprising a color filter provided on the second barrier layer.

Images