Display device and manufacturing method thereof

Abstract

A display device according to the present invention comprises a substrate, and a plurality of pixels and at least one reflective element positioned on the substrate. Each of the plurality of pixels comprises a pixel circuit and a light-emitting element, and the light-emitting element comprises a pixel electrode electrically connected with the pixel circuit, a first laminated structure on the pixel electrode, and a common electrode on the first laminated structure. The at least one reflective element has a lower electrode, a second laminated structure on the lower electrode, and a reflective film that overlaps the second laminated structure. The first laminated structure and the second laminated structure each include a plurality of inorganic semiconductor layers.

Description

[Technical Field]

[0001] 1. Field of the Invention The present invention relates to a display device, a lighting device, and a manufacturing method thereof. For example, the present invention relates to a display element or a lighting device including a light-emitting element containing an inorganic semiconductor material, and a manufacturing method thereof. [Background technology]

[0002] In recent years, light-emitting elements containing inorganic semiconductors (inorganic LEDs) have been used in various lighting devices and display devices. Inorganic LEDs can emit light with high brightness and have a long lifespan, so by using inorganic LEDs, it is possible to provide display devices and lighting devices with low power consumption and high reliability (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2021 / 161126 [Patent Document 2] U.S. Patent No. 10,937,815 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of one embodiment of the present invention is to provide a display device or lighting device having a novel structure, and a manufacturing method thereof. Alternatively, an object of one embodiment of the present invention is to provide a display device or lighting device that includes a light-emitting element containing an inorganic semiconductor and can be driven with high efficiency, and a manufacturing method thereof. [Means for solving the problem]

[0005] One embodiment of the present invention is a display device. The display device includes a substrate, a plurality of pixels located on the substrate, and at least one reflective element. Each of the plurality of pixels includes a pixel circuit and a light-emitting element. The light-emitting element includes a pixel electrode electrically connected to the pixel circuit, a first stacked structure on the pixel electrode, and a common electrode on the first stacked structure. The at least one reflective element includes a lower electrode, a second stacked structure on the lower electrode, and a reflective film overlapping the second stacked structure. Each of the first stacked structure and the second stacked structure includes a plurality of inorganic semiconductor layers.

[0006] One embodiment of the present invention is a lighting device. The lighting device includes a substrate, a plurality of light source units located on the substrate, and at least one reflecting element. Each of the plurality of light source units includes a light source circuit and a light-emitting element. The light-emitting element includes a first electrode electrically connected to the light source circuit, a first stacked structure on the first electrode, and a second electrode on the first stacked structure. The at least one reflecting element includes a lower electrode, a second stacked structure on the lower electrode, and a reflecting film overlapping the second stacked structure. Each of the first stacked structure and the second stacked structure includes a plurality of inorganic semiconductor layers.

[0007] One embodiment of the present invention is a method for manufacturing a display device, the method including: forming a plurality of pixel circuits on a substrate; forming a planarization film having a plurality of openings on the plurality of pixel circuits; forming a conductive film on the planarization film electrically connected to the plurality of pixel circuits through the plurality of openings; bonding a laminated body on a first transfer substrate and including a plurality of inorganic semiconductor layers to the conductive film; peeling off the first transfer substrate; molding the laminated body to form a plurality of first laminated structures and at least one second laminated structure; molding the conductive film to form a plurality of pixel electrodes overlapping the plurality of first laminated structures, each electrically connected to the plurality of pixel circuits, and a lower electrode overlapping the at least one second laminated structure and electrically isolated from any of the plurality of pixel circuits; forming a reflective film overlapping the at least one second laminated structure; forming a partition wall that embeds the at least one second laminated structure and the reflective film and covers edges of the plurality of first laminated structures; and forming a common electrode on the plurality of first laminated structures and the at least one second laminated structure, the common electrode being electrically connected to the first laminated structures and spaced from the reflective film.

[0008] One embodiment of the present invention is a method for manufacturing a lighting device. This manufacturing method includes forming a plurality of light source circuits on a substrate, forming a planarization film having a plurality of openings on the plurality of light source circuits, forming a conductive film on the planarization film that is electrically connected to the plurality of light source circuits through the plurality of openings, bonding a laminate located on a first transfer substrate and including a plurality of inorganic semiconductor layers to the conductive film, peeling off the first transfer substrate, shaping the laminate to form a plurality of first laminate structures and at least one second laminate structure, shaping the conductive film to form a plurality of first electrodes that overlap the plurality of first laminate structures, respectively, and are electrically connected to the plurality of light source circuits, and a lower electrode that overlaps at least one second laminate structure and is electrically isolated from any of the plurality of light source circuits, forming a reflective film that overlaps at least one second laminate structure, embedding the at least one second laminate structure and the reflective film, and forming a partition that covers the ends of the plurality of first laminate structures, and forming a second electrode that is electrically connected to the first laminate structure and is separated from the reflective film on the plurality of first laminate structures and at least one second laminate structure. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic top view of a display device according to an embodiment of the present invention. [Figure 2A] 1 is a schematic top view of a display device according to an embodiment of the present invention. [Figure 2B] 1 is a schematic top view of a display device according to an embodiment of the present invention. [Figure 3A] 1 is a schematic top view of a display device according to an embodiment of the present invention. [Figure 3B] 1 is a schematic top view of a display device according to an embodiment of the present invention. [Figure 4A] 1 is a schematic top view of a display device according to an embodiment of the present invention. [Figure 4B] 1 is a schematic top view of a display device according to an embodiment of the present invention. [Figure 5] 1 is a schematic end view of a display device according to an embodiment of the present invention; [Figure 6A]1 is a schematic end view of a display device according to an embodiment of the present invention; [Figure 6B] 1 is a schematic end view of a display device according to an embodiment of the present invention; [Figure 7] 1 is a schematic end view of a display device according to an embodiment of the present invention; [Figure 8] 1 is a schematic end view of a display device according to an embodiment of the present invention; [Figure 9] 5A to 5C are schematic end views illustrating a manufacturing method of a display device according to an embodiment of the present invention. [Figure 10] 5A to 5C are schematic end views illustrating a manufacturing method of a display device according to an embodiment of the present invention. [Figure 11] 5A to 5C are schematic end views illustrating a manufacturing method of a display device according to an embodiment of the present invention. [Figure 12] 5A to 5C are schematic end views illustrating a manufacturing method of a display device according to an embodiment of the present invention. [Figure 13] 5A to 5C are schematic end views illustrating a manufacturing method of a display device according to an embodiment of the present invention. [Figure 14] 5A to 5C are schematic end views illustrating a manufacturing method of a display device according to an embodiment of the present invention. [Figure 15] 5A to 5C are schematic end views illustrating a manufacturing method of a display device according to an embodiment of the present invention. [Figure 16] 5A to 5C are schematic end views illustrating a manufacturing method of a display device according to an embodiment of the present invention. [Figure 17] 5A to 5C are schematic end views illustrating a manufacturing method of a display device according to an embodiment of the present invention. [Figure 18] 5A to 5C are schematic end views illustrating a manufacturing method of a display device according to an embodiment of the present invention. [Figure 19] 5A to 5C are schematic end views illustrating a manufacturing method of a display device according to an embodiment of the present invention. [Figure 20] 5A to 5C are schematic end views illustrating a manufacturing method of a display device according to an embodiment of the present invention. [Figure 21] 5A to 5C are schematic end views illustrating a manufacturing method of a display device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, various embodiments of the present invention will be described with reference to the drawings, etc. However, the present invention can be embodied in various forms without departing from the spirit of the present invention, and should not be construed as being limited to the description of the embodiments exemplified below.

[0011] In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In this specification and each drawing, elements having the same function as those described in the previous drawings may be given the same reference numerals, and duplicated explanations may be omitted. This reference numeral is used to collectively represent multiple identical or similar structures, and when these are individually represented, a hyphen and a natural number are added after the reference numeral.

[0012] In this specification and claims, when expressing an aspect of placing another structure on top of a certain structure, the term "on top" is used, unless otherwise specified, to include both a case in which another structure is placed directly on top of a certain structure so as to be in contact with the certain structure, and a case in which another structure is placed above a certain structure via yet another structure.

[0013] In this specification and claims, the expression "a structure exposed from another structure" means a state in which a part of a structure is not covered by another structure, and includes a state in which the part not covered by another structure is covered by yet another structure. The state expressed by this expression also includes a state in which a structure is not in contact with another structure.

[0014] In the embodiment of the present invention, when multiple films are formed simultaneously in the same process, these films have the same layer structure, the same material, and the same composition, and therefore these multiple films are defined as existing in the same layer.

[0015] First Embodiment In this embodiment, the structure of a display device 100, which is one embodiment of the present invention, will be described.

[0016] 1. Overall structure Fig. 1 shows a schematic top view of a display device 100. As shown in Fig. 1, the display device 100 has a substrate 102, on which a plurality of pixels 104 and a plurality of reflective elements (not shown in Fig. 1) described below are provided. The minimum area that includes all of the pixels 104 and reflective elements, and the area surrounding this are defined as the display area and the peripheral area, respectively.

[0017] A driving circuit for driving the pixels 104 is provided in the peripheral region. In the example shown in Fig. 1, two scanning line driving circuits 106 sandwiching a plurality of pixels 104 therebetween, and a signal line driving circuit 108 including analog switches and the like are provided. Wiring (not shown) extends from the scanning line driving circuit 106 and the signal line driving circuit 108 to one side of the substrate 102 and is exposed at the edge of the substrate 102 to form terminals 110. The terminals 110 are electrically connected to a connector such as a flexible printed circuit (FPC) board (not shown), and power and video signals are supplied to the display device 100 from an external circuit via the connector. A desired video is displayed in the display region by driving the pixels 104, which are the smallest units that provide color information, in accordance with the video signals.

[0018] FIG. 2A is a schematic diagram illustrating an enlarged top view of a portion of a display area. As can be seen from FIG. 2A , the display area further includes a plurality of pixels 104 and at least one or more reflective elements 130. When a plurality of reflective elements 130 is provided, the plurality of pixels 104 and the plurality of reflective elements 130 can be arranged in a matrix having a plurality of rows and columns. FIG. 2A illustrates six pixels 104 and four reflective elements 130 arranged in a matrix of three rows and five columns. As shown in FIG. 2A , the plurality of pixels 104 and the plurality of reflective elements 130 can be arranged alternately in the row direction and / or the column direction. Alternatively, a plurality of pixels 104 may be arranged between two adjacent reflective elements 130, or a plurality of reflective elements 130 may be arranged between two adjacent pixels 104. For example, as shown in FIG. 2B , two pixels 104 may be sandwiched between two adjacent reflective elements 130 in the row direction.

[0019] Alternatively, as shown in FIGS. 3A and 3B, each of the multiple reflective elements 130 may be formed to have an opening surrounding one or more pixels 104. The number of pixels 104 surrounded by one reflective element 130 is arbitrary, and each reflective element 130 may surround three or more pixels 104. The number of pixels 104 surrounded by a reflective element 130 may be the same or different within the display area. Alternatively, as shown in FIGS. 4A and 4B, the display device 100 may be provided with one or more reflective elements 130 having a grid-like shape. That is, each reflective element 130 may have multiple openings, and one or more pixels 104 may be disposed in each opening. The following description will mainly focus on a typical example in which multiple pixels 104 and multiple reflective elements 130 are alternately arranged in the row direction, as shown in FIG. 2A. However, the following description can also be applied to other arrangements.

[0020] 2. Substrate and opposing substrate FIG. 5 is a schematic diagram of an end surface taken along the dashed line AA′ in FIG. 2 . As shown in FIG. 5 , the display device 100 includes a substrate 102 and an opposing substrate 150 opposing the substrate 102, with pixels 104 and reflective elements 130 disposed between them. The substrate 102 may be, for example, a glass substrate, a quartz substrate, or a single-crystal silicon substrate. Alternatively, a substrate containing a polymer such as polyimide, polyamide, or polycarbonate may be used. Similarly, the opposing substrate 150 may be a glass substrate, a quartz substrate, or a substrate containing a polymer. The substrate 102 and the opposing substrate 150 may be flexible. As described below, the display device 100 may be configured so that light generated by the pixels 104 is extracted through the opposing substrate 150. In this case, the opposing substrate 150 is configured to transmit visible light.

[0021] 3. Pixels (1) Pixel circuit Each pixel 104 is provided with a pixel circuit for controlling the pixel 104, either directly on the substrate 102 or via an undercoat 112 that functions as a barrier layer. The undercoat 112 is a film that prevents impurities such as alkali metal ions from penetrating from the substrate 102 into the pixel circuit, and can be composed of one or more films containing a silicon-containing inorganic compound such as silicon nitride or silicon oxide.

[0022] There are no restrictions on the configuration of the pixel circuit, and the pixel circuit may be configured using one or a plurality of transistors and capacitors depending on the driving method of the pixel 104. There are no restrictions on the configuration of the transistors included in the pixel circuit, and bottom-gate transistors, top-gate transistors, or both may be combined as appropriate. There are also no restrictions on the material included in the active layer of the transistor, and the pixel circuit may be configured using a silicon transistor having silicon in its active layer, or a transistor having an oxide semiconductor such as indium-gallium oxide or indium-gallium-zinc oxide in its active layer.

[0023] A planarization film 116 is provided on the pixel circuit to provide a flat upper surface. The planarization film 116 includes a polymer material such as acrylic resin, epoxy resin, polyimide resin, or polysiloxane resin. Optionally, a protective insulating film 118 composed of one or more films containing a silicon-containing inorganic compound may be provided on the planarization film 116.

[0024] (2) Light-emitting element The pixel 104 further includes a light-emitting element 120 electrically connected to the pixel circuit. The light-emitting element 120 basically includes a pixel electrode 122, a first stacked structure 124 on the pixel electrode 122, and a common electrode 126 on the first stacked structure 124. In the example shown in Fig. 5 , the pixel electrode 122 is connected to the transistor 114 in the pixel circuit through openings provided in the planarization film 116 and the protective insulating film 118, thereby electrically connecting the pixel circuit and the light-emitting element 120.

[0025] The pixel electrode 122 is an electrode that has the function of injecting carriers (holes or electrons) into the first laminated structure 124 and simultaneously reflecting light emitted from the first laminated structure 124 toward the common electrode 126. The pixel electrode 122 contains a conductive oxide that is transparent to visible light, such as indium-tin oxide (ITO) or indium-zinc oxide (IZO), a metal (zero-valent metal) such as silver or aluminum, or an alloy of these metals. The pixel electrode 122 may have either a single-layer structure or a laminated structure. When the pixel electrode 122 contains a transparent conductive oxide, a structure in which a film containing the transparent conductive oxide and a film containing the metal are laminated may be adopted, and the latter may be used to reflect light. Since light from the light-emitting element 120 is reflected by the pixel electrode 122 and extracted from the common electrode 126 side, the film containing the metal is formed to a thickness at least sufficient to block visible light.

[0026] 5, a conductive adhesive layer 123 may be provided on the pixel electrode 122 to improve adhesion to the first laminated structure 124. The conductive adhesive layer 123 may be made of, for example, an alloy such as solder, or a metal such as gold, silver, copper, or nickel.

[0027] The common electrode 126 is provided across the plurality of pixels 104. That is, the common electrode 126 is shared by the plurality of pixels 104. The common electrode 126 is electrically connected to the first stacked structures 124 of the plurality of pixels 104, but is arranged so as not to be electrically or physically connected to the second stacked structure (described below) 134 of the reflective element 130.

[0028] The common electrode 126 is configured to inject carriers into the first stacked structure 124 and to transmit light emitted from the first stacked structure 124. Specifically, the common electrode 126 is configured to contain a conductive oxide that transmits visible light, such as ITO or IZO, or a metal (zero-valent metal) such as aluminum, silver, or magnesium. When the common electrode 126 contains a zero-valent metal, the common electrode 126 is provided with a thickness that allows visible light to pass through.

[0029] FIG. 6A shows a schematic end view of the light-emitting element 120. As shown in FIG. 6A, the first stacked structure 124 is formed by stacking multiple functional layers containing inorganic semiconductors. Examples of inorganic semiconductors include compounds containing Group 13 and Group 15 elements. More specifically, examples include semiconductors containing aluminum, gallium, and / or indium, as well as nitrogen, phosphorus, and / or arsenic. Typical examples include gallium-based materials. Examples include gallium nitride-based materials such as gallium nitride (GaN), aluminum gallium nitride (AlGaN), and indium gallium nitride (InGaN), as well as gallium phosphide-based materials such as gallium phosphide (GaP) and aluminum indium gallium phosphide (AlGaInP). Each functional layer may further contain a dopant. Examples of dopants include elements such as silicon, germanium, magnesium, zinc, cadmium, and beryllium. By adding these elements, it becomes possible to control the valence electrons of each functional layer, and not only maintain the intrinsic (i-type) property, but also control the band gap and impart p-type or n-type conductivity.

[0030] The first stacked structure 124 is configured by combining multiple functional layers so that carriers are injected from the pixel electrode 122 and the common electrode 126, and the carriers recombine inside to emit light. There is no limit to the number of functional layers, as long as it includes at least a hole transport layer, an electron transport layer, and an emissive layer. For example, as shown in FIG. 6A , if the pixel electrode 122 and the common electrode 126 function as an anode and a cathode for injecting holes and electrons, respectively, the first stacked structure 124 can be formed by one or two functional layers 124-1 and 124-2 having p-type conductivity, one or two functional layers 124-4 and 124-5 having n-type conductivity, and a functional layer 124-3 that functions as an emissive layer. For example, functional layers 124-1 and 124-2 may be provided, each containing p-GaN and p-AlGaN, functional layers 124-4 and 124-5 may be provided, each containing n-AlGaN and n-GaN, and functional layer 124-3 may be sandwiched between these layers and serve as a light-emitting layer containing InGaN, GaAs, InP, GaN, etc. If the pixel electrode 122 and the common electrode 126 function as a cathode and an anode, respectively, the stacking order of the functional layers may be reversed.

[0031] The functional layer 124-3 functioning as a light-emitting layer may have a single-layer structure or a quantum well structure, which is a structure in which multiple thin films with different bandgaps and thicknesses of about 1 to 5 nm are alternately stacked, such as an alternating stack of InGaN and GaN, an alternating stack of GaInAsP and InP, or an alternating stack of AlInAs and InGaAs.

[0032] 4. Reflective elements The reflecting element 130 is an electrically floating element that functions to reflect a portion of the light emitted from the first stacked structure 124 of the light-emitting element 120 toward the counter substrate 150. The light emitted from the light-emitting element 120 travels approximately isotropically from the functional layer that functions as a light-emitting layer. However, if the traveling direction of the light exceeds a certain angle with respect to the normal to the substrate 102, the light repeatedly undergoes total reflection between the substrate 102 and the counter substrate 150 and is then attenuated. As a result, some of the light generated by the light-emitting element 120 cannot be extracted. However, by providing the reflecting element 130, the traveling direction of the light emitted from the first stacked structure 124 can be changed upward (toward the counter substrate 150) at a large angle with respect to the normal to the substrate 102. This suppresses total reflection, improves the light extraction efficiency, i.e., the efficiency of the display device 100, and reduces power consumption.

[0033] As shown in FIG. 5 , the reflective element 130 includes a lower electrode 132 and a second stacked structure 134 on the lower electrode 132. As will be described later, the lower electrode 132 is formed in the same process as the pixel electrode 122. Therefore, the lower electrode 132 can have the same structure as the pixel electrode 122. That is, the pixel electrode 122 and the lower electrode 132 can have the same composition, the number and stacking order of functional layers, and thickness. Similarly, the second stacked structure 134 is formed in the same process as the first stacked structure 124. Therefore, the second stacked structure 134 can have the same structure as the first stacked structure 124. That is, the first stacked structure 124 and the second stacked structure 134 can have the same composition, the number and stacking order of functional layers, and thickness. For example, if the first laminated structure 124 has functional layers 124-1 to 124-5 in order from the pixel electrode 122 side, the second laminated structure 134 is formed by laminating functional layers 134-1 to 134-5 having the same composition and structure as these functional layers 121-1 to 121-5 in order from the lower electrode 132 side (FIG. 6B). Although not shown, a conductive adhesive layer 123 may also be provided between the lower electrode 132 and the second laminated structure 134, as in the pixel 104.

[0034] A partition wall 140 is provided on the first stacked structure 124 and the second stacked structure 134. The partition wall 140 is formed so as to bury the lower electrode 132 and the second stacked structure 134 and not expose the second stacked structure 134. As a result, the second stacked structure 134 is separated from the common electrode 126 via the partition wall 140. Meanwhile, in the pixel 104, the partition wall 140 is provided so as to cover the end portion of the first stacked structure 124 and to expose the other portion. With this structure, the first stacked structure 124 and the common electrode 126 are electrically connected.

[0035] The partition wall 140 contains a polymer material such as an acrylic resin, an epoxy resin, a siloxane resin, or a polyimide resin. Therefore, the refractive index of the partition wall 140 is approximately 1.5 to 1.8. On the other hand, the second laminated structure 134, like the first laminated structure 124, is composed of multiple functional layers including inorganic semiconductors, and therefore reflects the characteristics of the inorganic semiconductors, and has a high refractive index, for example, approximately 2.2 to 2.5. Therefore, a large refractive index difference exists between the partition wall 140 and the second laminated structure 134, causing Fresnel reflection, which results in the reflection of light emitted from the first laminated structure 124.

[0036] In order to more efficiently reflect light toward the opposing substrate 150, the second stacked structure 134 is preferably configured so that its side surface is inclined from the normal to the lower electrode 132 (see FIG. 6B ). That is, the second stacked structure 134 is preferably configured so as to have a tapered shape in which the width (length in a plane parallel to the upper surface of the lower electrode 132) decreases with increasing distance from the lower electrode 132. The angle θ formed between the upper surface of the lower electrode 132 and the side surface of the second stacked structure 134 is selected, for example, from the range of 70° or more and less than 90°, or from 80° or more and less than 90°. As will be described later, the first stacked structure 124 and the second stacked structure 134 are formed in the same process. Therefore, the angle formed between the upper surface of the pixel electrode 122 and the side surface of the first stacked structure 124 is also the same or substantially the same as the angle θ.

[0037] To more efficiently reflect light emitted from the first laminated structure 124, a reflective film 136 may be provided on the second laminated structure 134, as shown in FIG. 7. The reflective film 136 preferably has a high reflectivity for visible light and is therefore configured to contain a metal such as aluminum, silver, tungsten, tantalum, molybdenum, or titanium. Alternatively, the reflective film 136 may be configured as a dielectric multilayer film, which is an alternating laminate of thin films of materials with different refractive indices, such as titanium oxide and silicon oxide. The reflective film 136 may be in contact with the lower electrode 132, as shown in FIG. 7, or may be in contact with the protective insulating film 118 or the planarizing film 116, although not shown. The reflective film 136 is also covered by a partition wall 140, isolating it from the common electrode 126.

[0038] 5. Other configurations As an optional configuration, a sealing film 142 may be provided on the common electrode 126. The sealing film 142 is provided to prevent impurities such as water from entering the light-emitting elements 120 and pixel circuits. The sealing film 142 contains, for example, a silicon-containing inorganic compound such as silicon nitride or silicon oxide, and / or a polymer such as an acrylic resin, an epoxy resin, or a polyimide resin. For example, a structure in which a film containing a polymer is sandwiched between films containing a silicon-containing inorganic compound can be employed. Furthermore, as an optional configuration, an overcoat 152 may be provided in contact with the counter substrate 150 to prevent impurities from entering from the counter substrate 150.

[0039] 6. Variations The display device 100 can also be configured so that light generated in the pixels 104 is extracted through the substrate 102. In this case, the substrate 102 is made of a glass substrate, a quartz substrate, a substrate containing a polymer, or the like, which is transparent to visible light. The pixel electrodes 122 are formed so as to contain a conductive oxide such as ITO or IZO which is transparent to visible light, while the common electrode 126 is configured so as to contain a metal such as silver or aluminum so as to reflect light emitted from the first stacked structure 124 toward the pixel electrodes 122.

[0040] 8, in order to efficiently reflect light emitted from the first stacked structure 124 toward the pixel electrode 122 by the reflective element 130, it is preferable to configure the second stacked structure 134 so as to have an inverse tapered shape in which the width increases as the distance from the lower electrode 132 increases. Since the first stacked structure 124 and the second stacked structure 134 are formed in the same process, the first stacked structure 124 also has an inverse tapered shape.

[0041] As described above, the display device 100 is provided with a plurality of pixels 104 and a plurality of reflective elements 130 as a mechanism for reflecting light obtained from the pixels 104 toward the opposing substrate 150 or the substrate 102. As a result, light that would not be used in conventional display devices due to total reflection can be used for display, and the display device 100 exhibits high efficiency and low power consumption. Furthermore, since the power required to obtain the same brightness can be reduced, the burden on each light-emitting element 120 is reduced, and as a result, the reliability of the display device 100 can be improved.

[0042] Although the present embodiment has been described as a display device, a similar configuration can also be used in a lighting device. In this case, a simpler structure can be adopted for the light source circuit corresponding to the pixel circuit. For example, a transistor or a capacitance element may not be provided, and a drive circuit or an external switch may be used to control the power and signals supplied to the light source element corresponding to the pixel 104.

[0043] Second Embodiment In this embodiment, a display device 200 having a different structure from the display device 100 described in the first embodiment will be described. Descriptions of configurations that are the same as or similar to those described in the first embodiment may be omitted.

[0044] Fig. 9 shows a schematic end view of the display device 200. Three pixels 104-1 to 104-3 are shown in Fig. 9. The display device 200 differs from the display device 100 in that a color conversion layer 154 is provided in at least some of the pixels 104, thereby enabling full-color display.

[0045] Specifically, each pixel 104 of the display device 200 is provided with a light-emitting element 120 capable of emitting ultraviolet to blue light. More specifically, each pixel 104 is provided with a light-emitting element 120 capable of emitting light having at least one peak in the wavelength range of 250 nm to 450 nm. For such short-wavelength light, gallium nitride, zinc selenide, or the like may be used in a functional layer functioning as a light-emitting layer. Furthermore, color conversion layers 154-1 and 154-2 are provided in a pixel for obtaining green light (pixel 104-2 in this example) and a pixel for obtaining red light (pixel 104-3 in this example), respectively. The color conversion layer 154 is provided, for example, between the opposing substrate 150 and the overcoat 152 or between the sealing film 142 and the overcoat 152 so as to overlap with the first stacked structure 124 of the corresponding pixel 104. Color conversion layers 154-1 and 154-2 contain a color conversion material that absorbs light emitted from light-emitting element 120 and emits green and red light, respectively, and a resin for dispersing the color conversion material. The color conversion material may be an organic or inorganic light-emitting material, or may be quantum dots. Examples of quantum dots include cadmium selenide, cadmium sulfide, cadmium telluride, zinc selenide, zinc oxide, and zinc sulfide, each having a particle size of several nanometers to 20 nanometers. Note that the pixel for obtaining blue light emission (pixel 104-1 in this example) may or may not require color conversion layer 154. If color conversion layer 154 is provided, a color conversion layer that absorbs light emitted from light-emitting element 120 and emits blue light may be used.

[0046] In this configuration, light obtained from the light-emitting element 120 of pixel 104-1 is extracted directly or via a color conversion layer (not shown) that emits blue light. In contrast, in pixels 104-2 and 104-3, light obtained from the light-emitting element 120 is converted into green and red light by color conversion layers 154-1 and 154-2, respectively. As a result, full-color display is possible by controlling the driving of pixel 104.

[0047] In order to prevent color mixing due to light from adjacent pixels 104, a light-shielding film (black matrix) 158 overlapping the reflective element 130 may be provided as an optional configuration. The light-shielding film 158 overlaps part or all of the second stacked structure 134 in the vertical direction. Furthermore, although not shown, each light-emitting element 120 may be configured to be capable of emitting white light, and a color filter may be provided in each pixel instead of the color conversion layer 154.

[0048] The display device 200 having the above-described structure can be used as a display device capable of full-color display. In addition, by applying the above-described structure to a lighting device, it is possible to provide lighting with a changeable illumination color.

[0049] Third Embodiment In this embodiment, a method for manufacturing a display device and a lighting device according to an embodiment of the present invention will be described. Here, a method for manufacturing the display device 100 described in the first embodiment will be described as an example. Descriptions of configurations that are the same as or similar to those described in the first and second embodiments may be omitted. Note that the display device 100 can be manufactured by forming various conductive films, insulating films, and semiconductor films on the substrate 102 and patterning them appropriately, but since the protective insulating film 118 can be formed using known methods and materials, detailed descriptions will be omitted.

[0050] A pixel circuit including a transistor 114 is formed on the substrate 102, and a planarization film 116 and a protective insulating film 118 are formed thereon (see FIGS. 5 and 7). After that, an opening reaching the transistor 114 is formed in the planarization film 116 and the protective insulating film 118 by etching, and a conductive film 160 electrically connected to the transistor 114 through the opening is formed over the entire display area (FIG. 10). The conductive film 160 may be formed using metalorganic chemical vapor deposition (MOCVD), which is a type of chemical vapor deposition (CVD), or a sputtering method. The conductive film 160 provides the pixel electrode 122 and the lower electrode 132 in a subsequent forming process. Therefore, the conductive film 160 is formed so that its composition and layer structure are identical to those employed in the pixel electrode 122 and the lower electrode 132, respectively.

[0051] The first stacked structure 124 and the second stacked structure 134 formed in the pixel 104 and the reflective element 130, respectively, are formed by a transfer method. That is, a stack that provides the first stacked structure 124 and the second stacked structure 134 is formed on a transfer substrate 170 that is different from the substrate 102, and then the stacked structure is transferred onto the conductive film 160. Therefore, the stacking order of the functional layers is reversed on the transfer substrate 170 and the substrate 102.

[0052] Specifically, as shown in FIG. 11 , first, a separation layer 172 is formed on a transfer substrate 170. The transfer substrate 170 may be any substrate that transmits laser light used to decompose the separation layer 172 in a laser lift-off (LLO) method, which will be described later. Specifically, a sapphire substrate, a glass substrate, a quartz substrate, or the like may be used. The separation layer 172 is a film containing a material that is decomposed by laser light, such as a film containing GaN. The thickness of the separation layer 172 may be appropriately selected within a range of 10 nm to 30 nm. Then, functional layers that provide the first stacked structure 124 and the second stacked structure 134 are sequentially formed on the separation layer 172. Since the transfer method reverses the order in which the layers are stacked, for example, if the first stacked structure 124 has functional layers 124-1, 124-2, 124-3, 124-4, and 124-5 in that order from the substrate 102 side (Figure 6A), functional layers 174-1, 174-2, 174-3, 174-4, and 174-5, which have the same composition and structure as functional layers 124-5, 124-4, 124-3, 124-2, and 124-1, respectively, are stacked in that order from the transfer substrate 170 side.

[0053] The separation layer 172 and the functional layer 174 may be formed by MOCVD or sputtering. The separation layer 172 and the functional layer 174 may each have a single crystal structure, a polycrystalline structure, or a microcrystalline structure.

[0054] After this, the functional layer 174 and the conductive film 160 are bonded together (FIG. 12). Before bonding, a conductive adhesive layer 123 may be formed on the conductive film 160. Specifically, the conductive adhesive layer 123 may be formed by applying solder or by applying and baking a paste in which fine metal particles such as gold, silver, copper, or nickel are dispersed in a resin. The transfer substrate 170 is then peeled off using the LLO method. Specifically, as indicated by the arrows in FIG. 12, laser light is irradiated through the transfer substrate 170. The wavelength of the laser light may be selected from wavelengths that can be absorbed by the release layer 172; for example, a KrF excimer laser (248 nm) may be used. This decomposes the release layer 172, resulting in a loss of adhesion between the transfer substrate 170 and the functional layer 174, allowing the transfer substrate 170 to be peeled off from the functional layer 174 (FIG. 13).

[0055] Subsequently, the functional layer 174 is formed by photolithography. That is, a resist mask (not shown) is appropriately formed on the functional layer 174, and the functional layer 174 exposed from the resist mask is removed by dry etching or wet etching, and then the resist mask is removed. As a result, the first stacked structure 124 and the second stacked structure 134 are formed on the conductive film 160 (FIG. 14). The etching is preferably performed so that the resulting first stacked structure 124 and second stacked structure 134 have tapered shapes.

[0056] Subsequently, the conductive film 160 is shaped by photolithography. That is, a resist mask (not shown) that covers the first stacked structure 124 and the second stacked structure 134 is appropriately formed on the conductive film 160, and the conductive film 160 exposed from the resist mask is removed by dry etching or wet etching, and then the resist mask is removed. As a result, a pixel electrode 122 that overlaps with the first stacked structure 124 and maintains electrical connection with the transistor 114, and a lower electrode 132 that overlaps with the second stacked structure 134 and is electrically isolated from all pixel circuits including the transistor 114 are formed ( FIG. 15 ).

[0057] Although not shown, when the first laminated structure 124 and the second laminated structure 134 are to be given an inverse tapered shape (see FIG. 8), the functional layer 174 is shaped on the transfer substrate 170 before bonding the functional layer 174 and the conductive film 160 to form the first laminated structure 124 and the second laminated structure 134 having a tapered shape. Also, before bonding the transfer substrate 170 and the substrate 102, the conductive film 160 is shaped in advance by etching to form the pixel electrode 122 and the lower electrode 132. Thereafter, the first laminated structure 124 and the second laminated structure 134 are bonded to the pixel electrode 122 and the lower electrode 132, respectively, and the transfer substrate 170 is peeled off.

[0058] When the reflective film 136 is provided, the reflective film 136 is provided so as to cover the first stacked structure 124 and the second stacked structure 134. The reflective film 136 may be formed by applying a CVD method or a sputtering method. Thereafter, a resist mask (not shown) is formed, followed by etching and removal of the resist mask, thereby forming a plurality of reflective films 136 overlapping the second stacked structure 134 (FIG. 16). Alternatively, as shown in FIG. 17, before forming the conductive film 160, the reflective film 136 may be provided so as to cover the first stacked structure 124, the second stacked structure 134, and the conductive film 160, and then a resist mask 178 may be formed, and the conductive film 160 and the reflective film 136 may be etched simultaneously or stepwise using the resist mask 178 and the first stacked structure 124 as masks (FIG. 18). Although it depends on the etching conditions (i.e., the degree of side etching), in this case, the side of the conductive film 160 and the side of the reflective film 136 may be located on the same plane, and the edge of the bottom surface of the first stacked structure 124 and the edge of the top surface of the pixel electrode 122 may coincide.

[0059] Next, the partition wall 140 is formed. The partition wall 140 may be formed by applying a photosensitive resin such as an acrylic resin, an epoxy resin, a polyimide resin, or a polysiloxane resin by spin coating, inkjet printing, printing, or the like, followed by exposure through a photomask, baking, and development. The partition wall 140 is formed so as to embed the second stacked structure 134 and the reflective film 136 of the reflective element 130, cover the end of the first stacked structure 124 of the pixel 104, and expose a part of the first stacked structure 124 (FIG. 16).

[0060] Thereafter, the common electrode 126 is formed using a method such as sputtering, and then the sealing film 142 is provided. The color conversion layer 154, color filter, and overcoat 152 are provided on the counter substrate 150, and then the counter substrate 150 and the substrate 102 are fixed to each other using an adhesive, thereby manufacturing the display device 100 (FIGS. 5 and 7). The formation of the common electrode 126 and the subsequent steps can be performed using known methods and materials, and therefore detailed explanations thereof will be omitted.

[0061] In the above-described method, the first laminated structure 124 and the second laminated structure 134 are formed by transferring the functional layer 174 provided on the transfer substrate 170 onto the substrate 102. That is, the above-described manufacturing method includes one transfer step. However, multiple transfer steps may be performed. In this case, as shown in FIG. 19 , a release layer 172 is formed on the transfer substrate 170, and then the functional layer 174 is formed thereon. The stacking order of the functional layer 174 is the same as the stacking order of the functional layers included in the first laminated structure 124 and the second laminated structure 134 on the substrate 102. Furthermore, since the transfer step is performed twice, it is preferable to provide a release layer 176 on the functional layer 174.

[0062] After this, the functional layer 174 is bonded to a transfer substrate (hereinafter, relay substrate) 180 different from the transfer substrate 170 (FIG. 20). Furthermore, the release layer 172 is decomposed by irradiating a laser beam from the transfer substrate 170 side, and the transfer substrate 170 is peeled off, resulting in the functional layer 174 laminated on the relay substrate 180 (FIG. 21). Subsequently, the relay substrate 180 and the substrate 102 are bonded together so that the functional layer 174 is sandwiched between them, and then the relay substrate 180 is peeled off using the LLO method. Furthermore, if a reverse tapered shape is to be imparted to the first stacked structure 124 or the second stacked structure 134, the functional layer 174 on the relay substrate 180 is formed to form a tapered shape, and then the relay substrate 180 is bonded to the substrate 102 on which the pixel electrode 122 and the lower electrode 132 have been formed in advance. The subsequent steps are similar to those described above, and therefore will not be described further.

[0063] In a manufacturing method according to one embodiment of the present invention, the reflective element 130 for improving the light extraction efficiency from the pixel 104 is formed simultaneously with the pixel 104. In other words, there is no need to add a new process step for providing the reflective element 130. Therefore, it is possible to manufacture a display device or lighting device with high efficiency without increasing manufacturing costs.

[0064] The above-described embodiments of the present invention can be combined as appropriate as long as they are not mutually inconsistent. Furthermore, a display device in which a person skilled in the art appropriately adds or deletes components or modifies the design, or adds or omits processes or modifies conditions, based on the display device of each embodiment, is also included in the scope of the present invention as long as it includes the gist of the present invention.

[0065] Even if there are other effects and advantages different from those brought about by the aspects of each of the above-mentioned embodiments, those that are clear from the description in this specification or that can be easily predicted by a person skilled in the art are naturally understood to be brought about by the present invention. [Explanation of symbols]

[0066] 100: display device, 102: substrate, 104: pixel, 104-1: pixel, 104-2: pixel, 104-3: pixel, 106: scanning line driving circuit, 108: signal line driving circuit, 110: terminal, 112: undercoat, 114: transistor, 116: planarizing film, 118: protective insulating film, 120: light emitting element, 121-1: functional layer, 122: pixel electrode, 123: conductive adhesive layer, 124: first laminated structure, 124-1: functional layer, 124-2: functional layer, 124-3: functional layer, 124-4: functional layer, 124-5: functional layer, 126: common electrode, 130: reflector reflective element, 132: lower electrode, 134: second laminated structure, 134-1: functional layer, 134-2: functional layer, 134-3: functional layer, 134-4: functional layer, 134-5: functional layer, 136: reflective film, 140: partition wall, 142: sealing film, 150: opposing substrate, 152: overcoat, 154: color conversion layer, 154-1: color conversion layer, 154-2: color conversion layer, 158: light-shielding film, 160: conductive film, 170: transfer substrate, 172: peeling layer, 174: functional layer, 174-1: functional layer, 174-2: functional layer, 174-3: functional layer, 174-4: functional layer, 174-5: functional layer, 176: peeling layer, 178: resist mask, 180: relay substrate, 200: display device

Claims

1. the substrate, and a plurality of pixels and at least one reflective element located on the substrate; Each of the plurality of pixels is pixel circuit, and a light-emitting element including a pixel electrode electrically connected to the pixel circuit, a first stacked structure on the pixel electrode, and a common electrode on the first stacked structure; the at least one reflective element is located between two adjacent pixels selected from the plurality of pixels; The at least one reflective element Lower electrode, a second stacked structure on the bottom electrode; and a reflective film overlapping the second laminated structure; The display device, wherein the first stacked structure and the second stacked structure each include a plurality of inorganic semiconductor layers.

2. 10. The display of claim 1, wherein the at least one reflective element is electrically floating.

3. the at least one reflective element includes a plurality of reflective elements; the plurality of pixels and the plurality of reflective elements are both arranged in a matrix form, The display device according to claim 1 , wherein the plurality of pixels and the plurality of reflective elements alternate with each other in a row direction or a column direction of the matrix shape.

4. The at least one reflective element includes a plurality of reflective elements; the plurality of pixels and the plurality of reflective elements are both arranged in a matrix form, The display device according to claim 3 , wherein a plurality of the pixels are sandwiched between two adjacent ones of the reflective elements in a row direction or a column direction of the matrix shape.

5. The display device of claim 1 , wherein the at least one reflective element has an opening surrounding one or more of the plurality of pixels.

6. The display device according to claim 1 , wherein the reflective film is separated from the common electrode by a partition wall.

7. The display device according to claim 6 , wherein the partition wall buries the reflective film and the second laminated structure of the at least one reflective element and covers an end portion of the first laminated structure of the plurality of pixels.

8. The display device according to claim 1 , wherein the widths of the first stacked structure and the second stacked structure decrease as the distance from the substrate increases.

9. The display device according to claim 1 , wherein the first stacked structure and the second stacked structure contain a gallium-based material.

10. forming a plurality of pixel circuits on a substrate; forming a planarization film having a plurality of openings on the plurality of pixel circuits; forming a conductive film on the planarization film, the conductive film being electrically connected to the plurality of pixel circuits through the plurality of openings; a laminate located on a first transfer substrate and including a plurality of inorganic semiconductor layers, and bonding the laminate to the conductive film; peeling off the first transfer substrate; shaping the laminate to form a plurality of first laminate structures and at least one second laminate structure; By forming the conductive film, a plurality of pixel electrodes respectively overlapping the plurality of first stacked structures and electrically connected to the plurality of pixel circuits; forming a lower electrode overlapping the at least one second stacked structure and electrically isolated from any of the plurality of pixel circuits; forming a reflective film overlapping the at least one second laminate structure; forming a partition wall that buries the at least one second laminated structure and the reflective film and covers the ends of the plurality of first laminated structures; and forming a common electrode on the plurality of first stacked structures and the at least one second stacked structure, the common electrode being electrically connected to the first stacked structures and spaced apart from the reflective film; A method for manufacturing a display device, wherein the at least one second stacked structure is located between two adjacent first stacked structures selected from the plurality of first stacked structures.

11. the substrate is a glass substrate or a quartz substrate; The manufacturing method according to claim 10 , wherein the first transfer substrate is a glass substrate, a single-crystal silicon substrate, or a single-crystal sapphire substrate.

12. The manufacturing method according to claim 10 , further comprising irradiating the laminate with laser light through the first transfer substrate before peeling off the first transfer substrate.

13. The manufacturing method according to claim 10 , wherein the stack is shaped such that widths of the plurality of first stack structures and the at least one second stack structure decrease with increasing distance from the substrate.

14. the at least one second laminated structure includes a plurality of second laminated structures; The manufacturing method described in claim 10, wherein the molding of the laminate is performed so that the plurality of first laminate structures and the plurality of second laminate structures are all arranged in a matrix shape, and so that the plurality of first laminate structures and the plurality of second laminate structures alternate in the row or column direction of the matrix shape.

15. The at least one second laminate structure includes a plurality of second laminate structures, The manufacturing method described in claim 10, wherein the molding of the laminate is performed so that the plurality of first laminate structures and the plurality of second laminate structures are all arranged in a matrix shape, and two or more first laminate structures selected from the plurality of first laminate structures are sandwiched between two adjacent second laminate structures in the row or column direction of the matrix shape.

16. The manufacturing method according to claim 10 , wherein the stack is formed such that the at least one second stack structure has an opening surrounding at least one of the plurality of first stack structures.

17. forming the laminate on a second transfer substrate; and The method of claim 10 further comprising transferring the stack from the second transfer substrate to the first transfer substrate.

18. The method of claim 10 , wherein the first stack structure and the at least one second stack structure comprise a gallium-based material.

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