Display device and manufacturing method thereof

Abstract

To provide a display device having high efficiency and excellent color reproducibility, and a manufacturing method capable of providing the display device at low cost.SOLUTION: A display device includes at least one pixel having a first subpixel, a second subpixel, and a third subpixel. The first and second subpixels have red and green emitting organic electroluminescent elements, respectively. The third subpixel has a blue emitting inorganic electroluminescent element. Each of the organic electroluminescent elements has an anode, a cathode, and an organic electroluminescent layer between the anode and the cathode. The inorganic electroluminescent element has an anode, a cathode, and an inorganic electroluminescent layer electrically connected to the anode and the cathode.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] One embodiment of the present invention relates to a display device including light-emitting elements in pixels, and a method for manufacturing the same. [Background technology]

[0002] In recent years, electroluminescent elements have been widely used in display devices and lighting devices. For example, display devices including organic electroluminescent elements (OLEDs) in each pixel, as well as display devices and signage in which inorganic electroluminescent elements (LEDs) are arranged in each pixel, are used in various fields. Patent Document 1 discloses that a display device having high color reproducibility can be provided by providing a resonant structure in each organic electroluminescent element in a display device including red, green, and blue light-emitting organic electroluminescent elements. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-106823 A 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 having a new structure and a manufacturing method thereof. Alternatively, an object of one embodiment of the present invention is to provide a display device having high efficiency and excellent color reproducibility, and a manufacturing method capable of providing the display device at low cost. [Means for solving the problem]

[0005] One embodiment of the present invention is a display device. The display device includes at least one pixel having a first subpixel, a second subpixel, and a third subpixel. The first subpixel and the second subpixel have red and green emitting organic electroluminescent elements, respectively. The third subpixel has a blue emitting inorganic electroluminescent element. Each of the organic electroluminescent elements has an anode, a cathode, and an organic electroluminescent layer between the anode and the cathode. The inorganic electroluminescent element has an anode, a cathode, and an inorganic electroluminescent layer electrically connected to the anode and the cathode.

[0006] One embodiment of the present invention is a method for manufacturing a display device. The method includes forming at least one pixel including a first subpixel, a second subpixel, and a third subpixel on a substrate, forming red-emitting and green-emitting organic electroluminescent elements in the first subpixel and the second subpixel, respectively, and forming a blue-emitting inorganic electroluminescent element in the third subpixel. Each of the organic electroluminescent elements includes an anode, a cathode, and an organic electroluminescent layer between the anode and the cathode. The inorganic electroluminescent element includes an anode, a cathode, and an inorganic electroluminescent layer electrically connected to the anode and the cathode. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic top view of a display device according to an embodiment of the present invention. [Figure 2A] FIG. 1 is a schematic top view of a display device according to an embodiment of the present invention. [Figure 2B] FIG. 1 is a schematic top view of a display device according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a schematic end view of an electroluminescent element included in a display device according to one embodiment of the present invention. [Figure 4A] FIG. 2 is a schematic end view of an inorganic electroluminescent element included in a display device according to one embodiment of the present invention. [Figure 4B] FIG. 2 is a schematic end view of a light-emitting layer of an inorganic electroluminescent element included in a display device according to one embodiment of the present invention. [Diagram 5] FIG. 1 is a schematic end view of a display device according to an embodiment of the present invention. [Figure 6]FIG. 1 is a schematic end view of a display device according to an embodiment of the present invention. [Figure 7] FIG. 1 is a schematic end view of a display device according to an embodiment of the present invention. [Figure 8A] FIG. 1 is a schematic top view of a display device according to an embodiment of the present invention. [Figure 8B] FIG. 1 is a schematic top view of a display device according to an embodiment of the present invention. [Figure 9] FIG. 1 is a schematic top view of a display device according to an embodiment of the present invention. [Figure 10] FIG. 1 is a schematic end view of a display device according to an embodiment of the present invention. [Figure 11A] 1A and 1B are schematic diagrams showing the relationship between the structure of a light-emitting element and current efficiency. [Figure 11B] 1A and 1B are schematic diagrams showing the relationship between the structure of a light-emitting element and current efficiency. [Figure 12A] 1A and 1B are schematic diagrams showing the relationship between the structure of a light-emitting element and current efficiency. [Figure 12B] 1A and 1B are schematic diagrams showing the relationship between the structure of a light-emitting element and current efficiency. [Figure 13] 5A to 5C are schematic end views illustrating a method for manufacturing a display device according to an embodiment of the present invention. [Figure 14] 5A to 5C are schematic end views illustrating a method for manufacturing a display device according to an embodiment of the present invention. [Figure 15] 5A to 5C are schematic end views illustrating a method for manufacturing a display device according to an embodiment of the present invention. [Figure 16] 5A to 5C are schematic end views illustrating a method for manufacturing a display device according to an embodiment of the present invention. [Figure 17] 5A to 5C are schematic end views illustrating a method for manufacturing a display device according to an embodiment of the present invention. [Figure 18] 5A to 5C are schematic end views illustrating a method for manufacturing a display device according to an embodiment of the present invention. [Figure 19] 5A to 5C are schematic end views illustrating a method for manufacturing a display device according to an embodiment of the present invention. [Figure 20] 5A to 5C are schematic end views illustrating a method for manufacturing a display device according to an embodiment of the present invention. [Figure 21]5A to 5C are schematic end views illustrating a method for manufacturing a display device according to an embodiment of the present invention. [Figure 22] 5A to 5C are schematic end views illustrating a method for manufacturing a display device according to an embodiment of the present invention. [Figure 23] 5A to 5C are schematic end views illustrating a method for manufacturing a display device according to an embodiment of the present invention. [Figure 24] 5A to 5C are schematic end views illustrating a method for manufacturing a display device according to an embodiment of the present invention. [Diagram 25] 5A to 5C are schematic end views illustrating a method for manufacturing a display device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, each embodiment 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 gist of the present invention, and should not be construed as being limited to the description of the embodiments exemplified below.

[0009] In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner 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 functions as those explained in the previous drawings may be given the same reference numerals, and duplicate explanations may be omitted.

[0010] In the present invention, when a single film is etched or irradiated with light to form multiple films, these multiple films may have different functions and roles. However, these multiple films originate from films formed as the same layer in the same process, and have the same layer structure and the same material. Therefore, these multiple films are defined as existing in the same layer.

[0011] In this specification and the claims, when describing an aspect in which a structure is placed on top of another 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 structure so as to be in contact with the structure, and a case in which another structure is placed above a structure via yet another structure.

[0012] In this specification and claims, the expression "a structure is exposed from another structure" means an embodiment in which a part of a structure does not overlap with another structure, and this part that does not overlap with another structure also includes an embodiment in which the part overlaps with yet another structure. In addition, the embodiment expressed by this expression also includes an embodiment in which the structure is not in contact with the other structure.

[0013] 1. Overall structure of the display device A schematic top view of a display device 100 according to one embodiment of the present invention is shown in FIG. 1. There is no restriction on the size of the display device 100. Therefore, the display device 100 may be a small-sized display device used in, for example, a mobile phone or a smartphone, or a medium-sized display device used in, for example, a television or a computer monitor. Alternatively, the display device 100 may be a large-sized display device such as an electronic bulletin board or signage.

[0014] As shown in FIG. 1, the display device 100 includes a substrate 102, on which various insulating films, semiconductor films, and conductive films are patterned and laminated. By appropriately combining these films, a plurality of pixels 120 and driving circuits (scanning line driving circuit 104, signal line driving circuit 106) for driving the pixels 120 are formed on the substrate 102. A single region surrounding all of the plurality of pixels 120 is a display region 112, and the driving circuits are provided in a region (frame region) outside the display region 112. An opposing substrate (not shown) is provided on the pixels 120, the scanning line driving circuit 104, and the signal line driving circuit 106. The pixels 120, the scanning line driving circuit 104, and the signal line driving circuit 106 are sealed and protected between the substrate 102 and the opposing substrate. A plurality of terminals 108 formed of conductive films are provided on the substrate 102, and the terminals 108 are connected to a connector 110 such as a flexible printed circuit (FPC) board. The terminals 108 are electrically connected to an external circuit (not shown) by the connector 110. Various signals and power for displaying images are supplied from the external circuit to the scanning line driving circuit 104 and the signal line driving circuit 106 via the connector 110 and the terminals 108. Note that either the scanning line driving circuit 104 or the signal line driving circuit 106, or both, do not need to be formed directly on the substrate 102; a driving circuit formed on a substrate (such as a semiconductor substrate) different from the substrate 102 may be provided on the substrate 102 or the connector 110.

[0015] 2. Pixel arrangement FIG. 2A shows a schematic top view of a part of the display region 112 of the display device 100. As shown in FIG. 2A, each pixel 120 is composed of a plurality of subpixels 122. Each subpixel 122 functions as a minimum unit for providing color information. There is no restriction on the number of subpixels 122 included in one pixel 120, but it is typically three. In the example shown in FIG. 2A, each subpixel 122 is composed of a first subpixel 122-1, a second subpixel 122-2, and a third subpixel 122-3, each of which includes a pixel circuit (described later). Light-emitting elements that provide three primary colors, that is, a red light-emitting element, a green light-emitting element, and a blue light-emitting element, are disposed in the first subpixel 122-1, the second subpixel 122-2, and the third subpixel 122-3, respectively. Signals for operating the pixel circuits are generated by the scanning line driving circuit 104 and the signal line driving circuit 106 based on various signals supplied from external circuits. When the pixel circuit is driven by the signal, the light-emitting element connected to the pixel circuit emits light, thereby enabling full-color display. Here, the red light-emitting element, the green light-emitting element, and the blue light-emitting element refer to elements that have emission peak wavelengths in the ranges of 650 nm to 750 nm, 500 nm to 650 nm, and 400 nm to 500 nm, respectively.

[0016] There is no restriction on the arrangement of the pixels 120. For example, as shown in FIG. 2A, a stripe arrangement may be adopted in which a first subpixel 122-1, a second subpixel 122-2, and a third subpixel 122-3 that respectively provide red, green, and blue are arranged in order in the row direction, and pixels 120 that provide the same emission color are arranged in the same column. Alternatively, although not shown, various arrangements such as a mosaic arrangement in which the first subpixel 122-1, the second subpixel 122-2, and the third subpixel 122-3 are arranged in order in both the row direction and the column direction, a delta arrangement, a pentile arrangement, etc. may be adopted. Alternatively, as shown in FIG. 2B, a plurality of pixels 120 may be arranged such that one or more first subpixels 122-1 and one or more second subpixels 122-2 are sandwiched between adjacent third subpixels 122-3.

[0017] 3. Structure of light-emitting element 3 shows schematic end views of red-, green-, and blue-emitting light-emitting elements 130 arranged in the first subpixel 122-1, the second subpixel 122-2, and the third subpixel 122-3, respectively. The red light-emitting element (hereinafter, the first light-emitting element) 130-1 and the green light-emitting element (hereinafter, the second light-emitting element) 130-2 arranged in the first subpixel 122-1 and the second subpixel 122-2, respectively, are organic electroluminescent elements, each having a structure in which a plurality of functional layers containing one or more types of organic compounds are arranged between a pair of electrodes. Meanwhile, the blue light-emitting element (hereinafter, the third light-emitting element) 130-3 arranged in the third subpixel 122-3 is an inorganic electroluminescent element, each having a structure in which a plurality of semiconductor films containing a first IIIB group element (group 13 element) and a first VB group element (group 15 element) are arranged between a pair of electrodes.

[0018] 3-1. Organic electroluminescent device Each of the first light emitting element 130-1 and the second light emitting element 130-2, which are organic electroluminescent elements, includes an anode 132 and a cathode 148 that face each other as a pair of electrodes, and has a plurality of functional layers between these electrodes. Examples of the functional layers include a hole injection layer 134, a hole transport layer 136, an electron blocking layer 138, a light emitting layer 140, a hole blocking layer 142, an electron transport layer 144, and an electron injection layer 146. Each functional layer may have a single layer structure or may be composed of a plurality of layers containing different materials. Each of the first light emitting element 130-1 and the second light emitting element 130-2 may include all of the functional layers described above, or may include only a portion of the functional layers. As an optional configuration, each of the first light emitting element 130-1 and the second light emitting element 130-2 may further include a cap layer 150 and / or a protective film 160 on the cathode 148. Hereinafter, the functional layers sandwiched between the anode 132 and the cathode 148 are also generally referred to as an organic electroluminescent layer (organic EL layer).

[0019] Each functional layer is formed by applying a wet film formation method such as an inkjet method, a spin coating method, a printing method, or a dip coating method, or a dry film formation method such as a vapor deposition method. By applying a potential difference between the anode 132 and the cathode 148, holes are injected from the former and electrons are injected from the latter into the functional layer, and the holes and electrons are recombined in the light-emitting layer 140. This forms an excited state of the light-emitting material contained in the light-emitting layer 140. When this excited state relaxes to the ground state, light with a wavelength corresponding to the energy difference between the excited state and the ground state is emitted, and can be observed as light emitted from each light-emitting element 130.

[0020] (1) Anode and cathode The anode 132 functions as a reflective electrode for injecting holes into the organic EL layer and efficiently reflecting light generated in the organic EL layer to the cathode 148. For this reason, the anode 132 can be formed using a metal with high reflectivity, such as silver or aluminum, or an alloy thereof. A film of a conductive oxide having light transmission properties may be formed on a film containing such a metal or alloy. Examples of the conductive oxide include indium-tin oxide (ITO) and indium-zinc (IZO). For example, the anode 132 may have a three-layer structure of a layer containing a conductive oxide, a layer containing a metal such as silver or aluminum, and a layer containing a conductive oxide.

[0021] On the other hand, the cathode 148 functions as a semi-transmissive semi-reflective electrode that injects electrons into the organic EL layer and reflects a part of the light emitted by the organic EL layer and transmits a part of the light. The cathode 148 may be a metal thin film containing a metal such as aluminum, magnesium, or silver or an alloy thereof and having a thickness that allows visible light to pass through. Alternatively, a conductive oxide having translucency such as ITO or IZO may be used. When the above-mentioned metal thin film is used as the cathode 148, a conductive oxide having translucency may be laminated on the metal thin film. The cathode 148 is provided so as to be shared by the adjacent first light-emitting element 130-1 and second light-emitting element 130-2. That is, the cathode 148 is provided so as to be continuous between the adjacent first sub-pixel 122-1 and second sub-pixel 122-2. However, as described later, the cathode 148 is provided so as not to overlap with the third light-emitting element 130-3 and to expose at least a part of the third sub-pixel 122-3 and the third light-emitting element 130-3.

[0022] By forming the anode 132 and the cathode 148 in this manner, a part of the light from the light emitting layer 140 is repeatedly reflected between the anode 132 and the cathode 148 and resonates. As a result, the light emission intensity (i.e., light emission efficiency) of the light emitting element 130 is increased in the front direction of the display device 100, and narrowed light emission can be extracted through the cathode 148. This improves the color purity of the light emitting element 130, and excellent color reproducibility can be imparted to the display device 100. Specifically, the optical distance between the anode 132 and the cathode 148, the optical distance from the light emitting layer 140 corresponding to the light emitting region to the anode 132, and the optical distance from the light emitting layer 140 to the cathode 148 are adjusted so that each of the first light emitting element 130-1 and the second light emitting element 130-2 forms a microcavity. For example, in each of the first light emitting element 130-1 and the second light emitting element 130-2, it is preferable to adjust the optical distance between the anode 132 and the cathode 148 to be 80% or more and 120% or less of an integer multiple of 1 / 2 of the emission peak wavelength of the light emitting material in the light emitting layer 140. It is also preferable to adjust the optical distance from the anode 132 to the light emitting layer 140 and the optical distance from the cathode 148 to the light emitting layer 140 to be 80% or more and 120% or less of an odd multiple of 1 / 4 (1 / 4 wavelength) of the emission peak wavelength of the light emitting material. Note that the optical distance is the product of the thickness of the film and the refractive index of the material contained in the film. Therefore, the optical distance between the anode 132 and the cathode 148 is the sum of the products of the thickness and the refractive index of each functional layer.

[0023] The optical adjustment is performed by appropriately selecting the thickness and stacking structure of each functional layer included in the organic EL layer. For example, the thickness and number of layers of the hole transport layer 136 and the electron transport layer 144 are appropriately adjusted to adjust the optical distance between the anode 132 and the cathode 148, the optical distance from the anode 132 to the light-emitting layer 140, and the optical distance from the cathode 148 to the light-emitting layer 140.

[0024] (2) Hole injection layer The hole injection layer 134 has a function of promoting the injection of holes from the anode 170 to the organic EL layer. The hole injection layer 134 can be made of a compound that is easy to inject holes into, that is ...

[0025] (3) Hole transport layer The hole transport layer 136 has a function of transporting holes injected into the hole injection layer 134 to the light emitting layer 140, and may be made of the same or similar materials as those usable for the hole injection layer 134. For example, a material may be used that has a deeper HOMO level than the hole injection layer 134, but the difference is about 0.5 eV or less. Typically, an aromatic amine such as a benzidine derivative may be used.

[0026] (4) Electron Blocking Layer The electron blocking layer 138 has a function of preventing electrons injected from the cathode 148 from passing through the light-emitting layer 140 and being injected into the hole transport layer 136 without contributing to recombination in the light-emitting layer 140, thereby confining the electrons within the light-emitting layer 140, and also prevents the excitation energy obtained in the light-emitting layer 140 from being transferred to the molecules of the hole transport layer. This makes it possible to prevent a decrease in luminous efficiency.

[0027] For the electron blocking layer 138, it is preferable to use a material that has a hole transporting property higher than or equal to the electron transporting property, a lowest unoccupied molecular orbital (LUMO) level shallower than the molecules in the light-emitting layer 140, and a large band gap. Specifically, it is preferable to use a material that has a triplet level 0.2 eV, 0.3 eV, or 0.5 eV or more higher than the light-emitting material contained in the light-emitting layer 140. Specifically, examples of such a material include aromatic amine derivatives, carbazole derivatives, 9,10-dihydroacridine derivatives, benzofuran derivatives, and benzothiophene derivatives.

[0028] (5) Light-emitting layer The light-emitting layer 140 has a so-called host-doped structure and includes a host material and a dopant. Examples of the host material include zinc and aluminum-based metal complexes, as well as oxadiazole derivatives, triazole derivatives, benzimidazole derivatives, quinoxaline derivatives, dibenzoquinoxaline derivatives, dibenzothiophene derivatives, dibenzofuran derivatives, pyrimidine derivatives, triazine derivatives, pyridine derivatives, bipyridine derivatives, phenanthroline derivatives, aromatic amine derivatives, and carbazole derivatives. The dopant functions as a light-emitting material, and examples of the dopant that can be used include phosphorescent materials such as iridium-based orthometal complexes, platinum porphyrin complexes, and rare earth complexes.

[0029] The first light-emitting element 130-1 disposed in the first subpixel 122-1 uses a phosphorescent material that emits red light. Specifically, iridium complexes having a pyrimidine skeleton such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) and bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III), iridium complexes having a pyrazine skeleton such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) and bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III), and iridium complexes having a pyridine skeleton such as tris(1-phenylisoquinolinato-N,C2')iridium(III) and bis(1-phenylisoquinolinato-N,C2')iridium(III) acetylacetonate can be used. Alternatively, platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) may be used.

[0030] The second light-emitting element 130-2 disposed in the second subpixel 122-2 uses a phosphorescent material that emits green light. Specifically, examples of the iridium complex include iridium complexes having a pyrimidine skeleton, such as tris(4-methyl-6-phenylpyrimidinato)iridium(III) and tris(4-t-butyl-6-phenylpyrimidinato)iridium(III), iridium complexes having a pyrazine skeleton, such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III), iridium complexes having a pyridine skeleton, such as tris(2-phenylpyridinato-N,C2')iridium(III) and bis(2-phenylpyridinato-N,C2')iridium(III) acetylacetonate, and rare earth metal complexes, such as tris(acetylacetonato)(monophenanthroline)terbium(III).

[0031] In the first light emitting element 130-1 and / or the second light emitting element 130-2, a thermally activated delayed fluorescence (TADF) material may be used instead of a phosphorescent material. Here, delayed fluorescence refers to light emission that has a spectrum similar to that of normal fluorescence but has a significantly long lifespan, and the lifespan is approximately 10 -6 seconds or more, preferably 10 -3seconds or more is preferable. Examples of the thermally activated delayed fluorescent material include fullerene and its derivatives, acridine derivatives such as proflavine, and eosin. Examples of the metal-containing porphyrin include magnesium, zinc, cadmium, tin, platinum, indium, or palladium. Examples of the metal-containing porphyrin include protoporphyrin-tin fluoride complex, mesoporphyrin-tin fluoride complex, hematoporphyrin-tin fluoride complex, coproporphyrin tetramethyl ester-tin fluoride complex, octaethylporphyrin-tin fluoride complex, etioporphyrin-tin fluoride complex, and octaethylporphyrin-platinum chloride complex. Furthermore, a heterocyclic compound having a π-excessive heteroaromatic ring and a π-deficient heteroaromatic ring, such as 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine, may be used.

[0032] (6) Hole Block Layer The hole blocking layer 142 has a function of preventing holes injected from the anode 132 from passing through the light-emitting layer 140 and being injected into the electron transport layer 144 without contributing to recombination, thereby confining the holes within the light-emitting layer 140, and also prevents the excitation energy obtained in the light-emitting layer 140 from being transferred to molecules in the electron transport layer 144. This makes it possible to prevent a decrease in luminous efficiency.

[0033] For the hole blocking layer 142, it is preferable to use a material having a higher or equal electron transporting ability than a hole transporting ability, a deeper HOMO level than the molecules in the light emitting layer 140, and a larger band gap. Specifically, the difference between the HOMO level of the molecules in the hole blocking layer 142 and that of the molecules in the light emitting layer 140 is preferably 0.2 eV, 0.3 eV, or 0.5 eV or more. It is also preferable to use a material having a triplet level 0.2 eV, 0.3 eV, or 0.5 eV or more higher than the light emitting material. Specifically, it is possible to use a metal complex having a relatively large band gap (for example, 2.8 eV or more), such as a phenanthroline derivative, an oxadiazole derivative, a triazole derivative, or a bis(2-methyl-8-quinolinolato)(4-hydroxy-biphenylyl)aluminum.

[0034] (7)Electron transport layer The electron transport layer 144 has a function of transporting electrons injected from the cathode 148 through the electron injection layer 146 to the light emitting layer 140. For the electron transport layer 144, a compound that is easily reduced (electron accepting) can be used. In other words, a compound with a shallow LUMO level can be used. For example, metal complexes containing a ligand having benzoquinolinol as a basic skeleton, such as 8-quinolinolatolithium, (tris(8-quinolinolato)aluminum, and tris(4-methyl-8-quinolinolato)aluminum, and metal complexes containing a ligand having oxadiazole or thiazole as a basic skeleton can be used. Examples of the central metal of the metal complex include aluminum, lithium, and zinc. In addition to these metal complexes, compounds having an electron-deficient heteroaromatic ring, such as triazine derivatives, hexaphenylbenzene derivatives, benzimidazole derivatives, azine derivatives, oxadiazole derivatives, thiazole derivatives, triazole derivatives, and phenanthroline derivatives, can be used.

[0035] (8)Electron injection layer The electron injection layer 146 can be made of a compound that promotes electron injection from the cathode 148 to the electron transport layer 144. For example, a mixture of a compound that can be used in the electron transport layer 144 and an electron donor such as lithium or magnesium can be used. Alternatively, an inorganic compound such as lithium fluoride or calcium fluoride can be used. (9) Cap layer The cap layer 150 is provided to form a microcavity on the cathode 148, thereby resonating the light extracted from the light emitting layer 140 via the cathode 148 again, thereby increasing the light emitting efficiency of the light emitting element 130 in the front direction of the display device 100 and narrowing the line width. Therefore, the cap layer 150 is preferably configured so that its optical distance is 80% or more and 120% or less of an odd multiple of a quarter wavelength of the peak of the light obtained from the light emitting layer 140. The cap layer 150 may have a single layer structure or may be configured of multiple layers.

[0036] The material contained in the cap layer 150 may be a material having a high transmittance in the visible light region. A preferred material is a material that can be formed by vapor deposition, spin coating, or inkjet. An example of such a material is an organic compound. The organic compound may be, for example, a material contained in the functional layer, or may be a polymer such as an acrylic resin, an epoxy resin, or a silicon resin. Alternatively, a polymer material containing fluorine may be used. Examples of the polymer material containing fluorine include polytetrafluoroethylene, polyvinylidene fluoride, derivatives thereof, polyvinyl ethers and polyimides having fluorine in the main chain or side chain, polymethacrylic acid esters, polyacrylic acid esters, and polysiloxanes. These polymers may be crosslinked within or between molecules. Alternatively, instead of an organic compound, an inorganic compound such as a metal fluoride such as lithium fluoride, magnesium fluoride, or calcium fluoride may be used.

[0037] The cap layer 150 is continuous between the first light emitting element 130-1 and the second light emitting element 130-2, but the third subpixel 122-3 is exposed from the cap layer 150. The structure of the cap layer 150, i.e., the composition and thickness, may be the same or different between the first light emitting element 130-1 and the second light emitting element 130-2. In the former case, the cap layer 150 having the same structure can be formed in the same process, so that the display device 100 can be formed at a lower cost. In addition, since the difference in the emission wavelength between the first light emitting element 130-1 and the second light emitting element 130-2, which respectively provide red and green light emission, is smaller than the difference in the emission wavelength between the first light emitting element 130-1 and the third light emitting element 130-3, which respectively provide red and blue light emission, a highly efficient microcavity can be formed even if the cap layer 150 having the same structure is formed so as to be shared by the first light emitting element 130-1 and the second light emitting element 130-2. Therefore, it is possible to improve the color purity and increase the light emission efficiency without impairing the light emission efficiency of the first light emitting element 130-1 and the second light emitting element 130-2, and the color reproducibility of the display device 100 is improved. When the cap layer 150 has a different structure between the first light emitting element 130-1 and the second light emitting element 130-2, the cap layer 150 is configured so that the optical path of the cap layer 150 of the first light emitting element 130-1 is larger than that of the second light emitting element 130-2. Therefore, for example, the cap layer 150 of the first light emitting element 130-1 may have a multi-layer structure, and the cap layer 150 of the second light emitting element 130-2 may have a single-layer structure.

[0038] (10) Protective film One of the functions of the protective film 160 is to prevent impurities such as water and oxygen from entering the first light emitting element 130-1 and the second light emitting element 130-2 from the outside. For example, one or more inorganic films containing a silicon-containing inorganic compound such as silicon nitride can be used as the protective film 160. Alternatively, a structure in which an organic film containing a polymer such as an epoxy resin or an acrylic resin is sandwiched between inorganic films containing a silicon-containing inorganic compound may be adopted. When the cap layer 150 is provided, the protective film 160 is provided on the cap layer 150 so as to be in contact with the cap layer 150. When the cap layer 150 is not provided, the protective film 160 can be provided on the cathode 148 so as to be in contact with the cathode 148.

[0039] 3-2. Inorganic electroluminescent device As shown in FIG. 3, the third light emitting element 130-3, which is an inorganic electroluminescent element, has an anode 170 and a cathode 182, and includes a plurality of inorganic semiconductor films between them, each containing a first IIIB group element (group 13 element) and a first VB group element (group 15 element). The plurality of inorganic semiconductor films includes at least a light emitting layer 176, an electron transport layer 178 and a hole transport layer 174 located above and below the light emitting layer 176, and may further include a hole injection layer 172 between the anode 170 and the hole transport layer 174, and an electron injection layer 180 between the cathode 182 and the electron transport layer 178. The third light emitting element 130-3 may include a protective film as an optional configuration. Hereinafter, the inorganic semiconductor films provided between the anode 170 and the cathode 182 may be collectively referred to as an inorganic electroluminescent layer (inorganic EL layer).

[0040] As shown in Fig. 3, the third light-emitting element 130-3 can be configured so that the anode 170 and the cathode 182 overlap each other in the vertical direction (the normal direction of the substrate 102) and the inorganic EL layer is sandwiched between the anode 170 and the cathode 182. Alternatively, as shown in Fig. 4, the anode 170 and the cathode 182 may be disposed on the same side of the inorganic EL layer. In this case, the anode 170 and the cathode 182 do not overlap each other in the vertical direction, and the cathode 182 is disposed above (on the anode 170 side of) the electron injection layer 180 (or the electron transport layer 178 when the electron injection layer 180 is not provided). The cathode 182 is exposed from the hole injection layer 172, the hole transport layer 174, the light-emitting layer 176, and the electron transport layer 178.

[0041] (1) Anode and cathode The anode 170 and the cathode 182 are electrically connected to the inorganic EL layer and have the function of injecting holes and electrons into the inorganic EL layer, respectively. The anode 170 and the cathode 182 can be made of a transparent conductive oxide such as ITO or IZO, or a metal such as palladium, gold, silver, indium, or aluminum, or a thin film of an alloy thereof. The third light-emitting element 130-3 shown in FIG. 3 is configured so that light obtained in the light-emitting layer 176 is extracted from the cathode 182 side. For this reason, the cathode 182 is preferably made of a transparent conductive oxide, or a thin film of a metal or alloy having a thickness that allows visible light to pass through. For example, the cathode 182 may be a laminate of a film containing a transparent conductive oxide and a film that covers a part of this film and contains a metal such as gold. On the other hand, the anode 170 is preferably formed to contain a metal so as to efficiently reflect the light from the light-emitting layer 176. 4A, the light obtained in the light-emitting layer 176 is extracted via the anode 170. For this reason, the anode 170 contains a transparent conductive oxide, and is, for example, a laminate of a film containing a transparent conductive oxide and a film containing a metal such as gold.

[0042] (2) Inorganic EL layer The hole injection layer 172, the hole transport layer 174, the light emitting layer 176, the electron transport layer 178, and the electron injection layer 180 constituting the inorganic EL layer may each have a single layer structure, or may have a laminated structure in which a plurality of layers are laminated. Examples of semiconductors constituting these inorganic semiconductor films 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), and gallium phosphide-based materials such as gallium phosphide (GaP) and aluminum indium gallium phosphide (AlGaInP). The inorganic semiconductor film may further include 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 to maintain the intrinsic (i-type) properties, but also to control the band gap and impart p-type or n-type conductivity.

[0043] Hole transport layer 174 and hole injection layer 172 are made of inorganic semiconductor films imparted with p-type conductivity, while electron injection layer 180 and electron transport layer 178 are made of inorganic semiconductor films imparted with n-type conductivity. For example, electron injection layer 180, electron transport layer 178, hole transport layer 174, and hole injection layer 172 can be configured to contain n-type gallium nitride, n-type aluminum gallium nitride, p-type aluminum gallium nitride, and p-type gallium nitride, respectively.

[0044] The light emitting layer 176 is configured to emit blue light. More specifically, it is configured to exhibit one or more emission peak wavelengths in the range of 400 nm to 500 nm. For example, the light emitting layer 176 may be a single layer structure of indium gallium nitride, or may have a quantum well structure as shown in FIG. 4B. The quantum well structure is a structure in which a plurality of thin films having different band gaps and thicknesses of about 1 to 6 nm are alternately stacked. That is, a plurality of high band gap layers 176-1 and low band gap layers 176-2 are alternately stacked. Preferably, the high band gap layer 176-1 is provided as the top layer and the bottom layer. Examples of the quantum well structure include an alternating stack of indium gallium nitride and gallium nitride, an alternating stack of indium gallium arsenide phosphide (GaInAsP) and indium phosphide (InP), an alternating stack of aluminum indium arsenide (AlInAs) and indium gallium arsenide (InGaAs), and the like. In the case of an alternating laminate of indium gallium nitride and gallium nitride, the preferred composition of indium is 35 mass % or less.

[0045] The size of the third light emitting element 130-3, i.e., the area of ​​the inorganic EL layer in a plane parallel to the upper surface of the substrate 102, can be appropriately determined in consideration of the sizes of the pixels 120 and the subpixels 122. A preferred area of ​​the inorganic EL layer is, for example, 2×10 2 μm 2 More than 2×10 5 μm 2 Less than or equal to 1×10 3 μm 2 More than 2×10 5 μm 2or less. Alternatively, it is preferable that one side of the smallest rectangle surrounding the light-emitting region is 15 μm to 150 μm or 30 μm to 100 μm. Since each semiconductor film of the third light-emitting element 130-3 is formed using a chemical vapor deposition (CVD) method or the like and then etched, the peripheral portion of the semiconductor film is easily damaged by etching. Therefore, by fabricating the third light-emitting element 130-3 to have the above size, the contribution of the peripheral portion can be relatively reduced. As a result, the decrease in light-emitting efficiency caused by etching damage can be suppressed, and the third light-emitting element 130-3 exhibits high light-emitting efficiency.

[0046] 4. Light-emitting element arrangement FIG. 5 shows a schematic end view of three subpixels 122 included in one pixel 120. In the following schematic end views including FIG. 5, some functional layers may not be illustrated for ease of viewing. As described above, each subpixel 122 is provided with a pixel circuit and a pixel electrode 124 electrically connected to the pixel circuit. The configuration of the pixel circuit can be determined arbitrarily, and the pixel circuit is configured by appropriately combining one or more transistors and one or more capacitive elements. The pixel circuit of the third subpixel 122-3 in which the third light-emitting element 130-3, which is an inorganic electroluminescent element, is provided may have the same structure as the pixel circuit of the first subpixel 122-1 or the second subpixel 122-2, or may have a different structure.

[0047] There is no restriction on the configuration of the transistor provided in the pixel circuit, and a top-gate type transistor, a bottom-gate type transistor, or a transistor having a structure in which a channel is sandwiched between a pair of gate electrodes may be used. FIG. 5 shows a transistor 200 as one of the configurations of the pixel circuit. This transistor 200 is provided on the substrate 102 directly or via an undercoat 114 of any configuration. The undercoat 114 is composed of one or more films containing a silicon-containing inorganic compound such as silicon nitride or silicon oxide. The transistor 200 is composed of a semiconductor film 202 that constitutes a channel, a gate insulating film 204 on the semiconductor film 202, a gate electrode 206 on the gate insulating film 204, an interlayer insulating film 208 on the gate electrode 206, and terminals 210 and 212 located on the interlayer insulating film 208 and electrically connected to the semiconductor film 202.

[0048] A planarization film 116 is provided on the transistor 200 to absorb unevenness resulting from a pixel circuit including the transistor 200 and provide a flat surface. A pixel electrode 124 is electrically connected to the transistor 200 through an opening provided in the planarization film 116. The pixel electrode 124 may be directly connected to a terminal 212 of the transistor 200 or may be connected via a conductive film (not shown). A partition wall 118 is provided on the pixel electrode 124 to cover the end portion thereof, thereby separating adjacent light-emitting elements 130.

[0049] In the first light-emitting element 130-1 and the second light-emitting element 130-2, the pixel electrode 124 functions as the anode 132. Therefore, the first light-emitting element 130-1 and the second light-emitting element 130-2 are fabricated by sequentially forming an organic EL layer and a cathode 148 on the pixel electrode 124. The cathode 148 is connected to a first common wiring (not shown) and a constant potential is applied to it.

[0050] On the other hand, in the third subpixel 122-3, a third light-emitting element 130-3 including an anode 170, an inorganic EL layer, and a cathode 182, which are separately fabricated on a substrate such as a sapphire single crystal substrate different from the substrate 102, is connected to the pixel electrode 124. This connection is made using a conductive adhesive 152 such as solder. In other words, the anode 170 of the third light-emitting element 130-3 is connected to the pixel circuit via the pixel electrode 124. As shown in FIG. 6, the cathode 182 of the third light-emitting element 130-3 is provided on the substrate and is connected to a second common wiring 126 to which a constant potential is supplied. The first common wiring and the second common wiring 126 may be the same, or different potentials may be applied. As shown in FIG. 6, the connection between the cathode 148 and the second common wiring 126 may be made by wire bonding using a conductive wire 128. When the anode 170 and cathode 182 of the third light-emitting element 130-3 are located on the same side (FIG. 4), the anode 170 and cathode 182 may be connected to the pixel electrode 124 and the second common wiring 126, respectively, via adhesive 152, as shown in FIG. 7. Although not shown, the side on which the anode 170 and cathode 182 are provided may be disposed on the opposite side to the substrate 102, and the anode 170 and cathode 182 may be connected to the pixel electrode 124 and the second common wiring 126, respectively, by wire bonding.

[0051] The optional protective film 184 is composed of one or more films including a silicon-containing inorganic compound, such as silicon nitride or silicon oxide. Alternatively, the protective film 184 may include boron nitride. As shown in Figures 5 and 7, the protective film 184 may be provided to cover a portion of the anode 170 and / or a portion of the cathode 182. The protective film 184 is further provided to cover at least a portion of the side surface of the inorganic EL layer.

[0052] As described above, the cathode 148 is continuous between the adjacent first subpixel 122-1 and second subpixel 122-2, and the cathode 148 is shared by the first light-emitting element 130-1 and the second light-emitting element 130-2 (see FIGS. 5 and 7). Therefore, as shown in FIGS. 8A and 8B, the display device 100 includes a plurality of cathodes 148 connected to a plurality of pixels 120, which are arranged in a stripe or comb shape. On the other hand, the third light-emitting element 130-3 is fabricated on a substrate different from the substrate 102 and then arranged in the third subpixel 122-3, and therefore, as shown in FIG. 5 and the schematic top view of FIG. 9, the cathode 182 is separated from the cathodes 148 of the first light-emitting element 130-1 and the second light-emitting element 130-2. Furthermore, when a protective film 160 is provided on the first light-emitting element 130-1 and the second light-emitting element 130-2, and a protective film 184 is also provided on the third light-emitting element 130-3, these protective films 160, 184 may be separated from each other, or, as shown in FIG. 10, the protective film 160 may cover a portion of the protective film 184.

[0053] As described above, in the display device 100, red and green light are obtained from the first light-emitting element 130-1 and the second light-emitting element 130-2 arranged in the first subpixel 122-1 and the second subpixel 122-2, respectively, and blue light is obtained from the third light-emitting element 130-3 arranged in the third subpixel 122-3. Since the first light-emitting element 130-1 and the second light-emitting element 130-2 use a light-emitting material exhibiting phosphorescence or thermally activated delayed fluorescence, highly efficient light emission is possible. For example, the first light-emitting element 130-1 and the second light-emitting element 130-2 can emit light with current efficiencies exceeding 60 cd / A and 140 cd / A, respectively. On the other hand, since the third light-emitting element 130-3 is an inorganic electroluminescent element rather than an organic electroluminescent element with low current efficiency, it is also possible to achieve a current efficiency exceeding 80 cd / A. For this reason, each pixel 120 can exhibit extremely high current efficiency, and as a result, the power consumption of the display device 100 can be significantly reduced. Furthermore, since the amount of current supplied to each light emitting element 130 can be reduced, a display device with a long life can be provided.

[0054] More specifically, when all the light-emitting elements 130 are organic electroluminescent elements, the first light-emitting element 130-1 and the second light-emitting element 130-2, which are red and green light-emitting elements, respectively, use a light-emitting material that exhibits phosphorescence or thermally activated delayed fluorescence. However, for the third light-emitting element 130-3, which is a blue light-emitting element, a fluorescent material is used because it is difficult to fabricate a phosphorescent organic electroluminescent element that provides blue light emission with high color purity and has sufficient reliability. For this reason, the current efficiency of the third light-emitting element 130-3 is less than 10 cd / A. As a result, as shown in FIG. 11A, although the first light-emitting element 130-1 and the second light-emitting element 130-2 achieve high current efficiency, the current efficiency of the third light-emitting element 130-3 is extremely low, and the current efficiency of the white light emission obtained by turning on all the light-emitting elements 130 is also about 50 cd / A.

[0055] On the other hand, when all the light emitting elements 130 are inorganic electroluminescent elements, high current efficiency is obtained not only for the first light emitting element 130-1 and the second light emitting element 130-2 but also for the third light emitting element 130-3 in which a blue light emitting element is arranged. However, as described above, as the light emitting element becomes smaller, the current efficiency decreases due to etching damage. Therefore, when all the light emitting elements 130 are inorganic electroluminescent elements, as shown in FIG. 11B, the current efficiency may decrease significantly depending on the size of the light emitting element, and the high efficiency of the inorganic electroluminescent elements may not be effectively utilized.

[0056] It should be noted here that the current efficiency of organic electroluminescent elements has almost no size dependency. Therefore, as in one embodiment of the present invention, by obtaining red and green light emission from organic electroluminescent elements in the first light emitting element 130-1 and the second light emitting element 130-2, high current efficiency can be obtained regardless of the size of the element (see FIG. 12A). In addition, in the third light emitting element 130-3, blue light emission is obtained from an inorganic electroluminescent element, and although there is a dependency on the size of the element, a current efficiency that is still very high compared to that of an organic electroluminescent element emitting blue light can be realized. Therefore, in any of the light emitting elements 130, light emission can be obtained with high current efficiency, and it is also possible to obtain white light emission with a current efficiency of around 100 cd / A.

[0057] Also, as described above, even if a microcavity is formed by forming a cap layer 150 that is continuous between the first light emitting element 130-1 and the second light emitting element 130-2 and has the same structure, a highly efficient microcavity can be formed in both elements. (See FIG. 5 and FIG. 7.) Therefore, even if the thickness of the cap layer 150 is the same between the first light emitting element 130-1 and the second light emitting element 130-2, a current efficiency that is comparable to that of the case where the cap layer 150 having an optimized thickness is used for each of the first light emitting element 130-1 and the second light emitting element 130-2 (FIG. 12A) can be obtained (FIG. 12B). Therefore, by applying one of the embodiments of the present invention, a highly efficient display device can be provided while reducing the number of steps for forming the cap layer 150. This contributes to reducing the manufacturing cost of the display device 100.

[0058] 5. Display device manufacturing method An example of a method for manufacturing the display device 100 will be described below with reference to Figures 13 to 19. As with Figure 5 and the like, some functional layers may not be shown.

[0059] First, a plurality of pixels 120 are formed on a substrate 102 (FIG. 13). The steps up to this point can be performed by appropriately combining known methods and materials, so a description thereof will be omitted.

[0060] (1) Formation of organic electroluminescent device Next, the first light emitting element 130-1 and the second light emitting element 130-2, which are organic electroluminescent elements, are formed. Specifically, a deposition mask (metal mask) 220 that exposes the first subpixel 122-1 and the second subpixel 122-2 and covers the third subpixel 122-3 is placed on the substrate 102 (FIG. 13). At this time, the partition wall 118 and the deposition mask 220 may be in contact with each other. In this state, the functional layer and the cathode 148 that constitute the organic EL layer are sequentially formed by deposition (FIG. 14). When the structure or material of the functional layer is different between the first light-emitting element 130-1 and the second light-emitting element 130-2, a coating mask (a deposition mask covering one of the first subpixel 122-1 and the second subpixel 122-2 and the third subpixel 122-3, and a deposition mask covering the other of the first subpixel 122-1 and the second subpixel 122-2 and the third subpixel 122-3) may be appropriately used to form a functional layer for each subpixel 122. For example, since at least the light-emitting material contained in the light-emitting layer 140 is different between the first light-emitting element 130-1 and the second light-emitting element 130-2, the light-emitting layer 140 is formed for each subpixel 122. In the first light-emitting element 130-1 having a long emission wavelength, the optical path length of the organic EL layer for forming an appropriate microcavity is longer than that of the second light-emitting element 130-2, so that, for example, as shown in Fig. 15, the first hole transport layer 136-1 common to the first light-emitting element 130-1 and the second light-emitting element 130-2 may be formed using a deposition mask exposing the first subpixel 122-1 and the second subpixel 122-2, and then the second hole transport layer 136-2 may be formed on the first hole transport layer 136-1 using a paint mask exposing only the first subpixel 122-1. Although a detailed description is omitted, the electron transport layer 144 may also be composed of a first electron transport layer common to the first light-emitting element 130-1 and the second light-emitting element 130-2, and a second electron transport layer selectively provided only in the first light-emitting element 130-1.

[0061] When forming the cap layer 150, a deposition mask is appropriately used, and the cap layer 150 is formed on the cathode 148 by applying a deposition method, as in the case of the functional layer (FIG. 16). When the structure (thickness, composition) of the cap layer 150 is the same between the first light emitting element 130-1 and the second light emitting element 130-2, the cap layer 150 that is continuous between the first light emitting element 130-1 and the second light emitting element 130-2 may be formed in one deposition process. When the thickness of the cap layer 150 is different between the first light emitting element 130-1 and the second light emitting element 130-2, as shown in FIG. 17, the first cap layer 150-1 is formed that is continuous between the first light emitting element 130-1 and the second light emitting element 130-2 and has the same thickness between the first light emitting element 130-1 and the second light emitting element 130-2. Thereafter, a coating mask that selectively exposes the first light emitting element 130-1 having a longer emission wavelength is used, and the second cap layer 150-2 is formed on the first subpixel 122-1 by vapor deposition.

[0062] When forming the protective film 160, for example, a CVD method may be used to form silicon nitride, silicon oxide, or a laminate of these on the cathode 148 or the cap layer 150. At this time, as shown in Fig. 18, the protective film 160 may also be formed on the third subpixel 122-3, and then the protective film 160 may be etched to expose the pixel electrode 124 of the third subpixel 122-3 (Fig. 19).

[0063] (2) Formation of inorganic electroluminescent device Thereafter, the third light-emitting element 130-3 is disposed in the third subpixel 122-3. As described above, the third light-emitting element 130-3 can be disposed by connecting the anode 170 to the pixel electrode 124 using the conductive adhesive 152, and connecting the cathode 182 to the second common wiring 126 by wire bonding. Alternatively, the anode 170 and the cathode 182 may be connected to the pixel electrode 124 and the second common wiring 126 by wire bonding, respectively. The inorganic EL layer of the third light-emitting element 130-3 is preferably formed by metal organic vapor phase deposition or molecular beam epitaxy.

[0064] Through the above steps, the display device 100 shown in Fig. 5 can be manufactured. In this step, the first light-emitting element 130-1 and the second light-emitting element 130-2 are formed before the third light-emitting element 130-3. Therefore, the deposition mask 220 and the coating mask can be disposed near the substrate 102 (for example, so as to contact the partition wall 118) to form the functional layer, which makes it possible to prevent the organic compound vaporized during deposition from entering the gap between the deposition mask 220 and the substrate 102. Therefore, the functional layer can be disposed more accurately.

[0065] (3) Variations However, the manufacturing method of the display device 100 is not limited to this, and the third light emitting element 130-3, which is an inorganic electroluminescent element, may be disposed in the third subpixel 122-3 first (FIG. 20), and then the first light emitting element 130-1 and the second light emitting element 130-2, which are organic electroluminescent elements, may be formed. In this modification, it is possible to completely eliminate the influence of heat during wire bonding on the first light emitting element 130-1 and the second light emitting element 130-2.

[0066] In addition, the method of manufacturing the third light emitting element 130-3, which is an inorganic electroluminescent element, is not limited to the above-mentioned method. Specifically, the third light emitting element 130-3 may be formed by forming an inorganic EL layer and a cathode 182 on the substrate 102 by a sputtering method, instead of disposing the third light emitting element 130-3, which is manufactured on a substrate different from the substrate 102 and has an anode 170 and a cathode 182, in the third subpixel 122-3. In this case, for example, the pixel electrode 124 is made to function as the anode 170, and a buffer layer 186 is formed thereon by a CVD method, a sputtering method, or the like (FIG. 21). The buffer layer 186 is configured to contribute to the promotion of crystallization of the inorganic EL layer provided thereon, and by forming the inorganic EL layer on the buffer layer 186, the occurrence of crystal defects in the inorganic EL layer can be effectively suppressed. Since the buffer layer 186 is also required to be conductive, the buffer layer 186 may be formed using, for example, conductive metal nitrides such as aluminum indium nitride, titanium nitride, gallium nitride, and aluminum nitride, semiconductors such as silicon and germanium, and metals such as titanium, aluminum, silver, nickel, copper, strontium, rhodium, palladium, iridium, platinum, and gold. If necessary, annealing may be performed on the buffer layer 186 to promote crystallization. If the pixel electrode 124 has a function of promoting crystallization of the inorganic EL layer, the buffer layer 186 may be omitted and the inorganic EL layer may be formed directly on the pixel electrode 124.

[0067] Next, semiconductor films constituting inorganic EL layers, such as the hole injection layer 172, hole transport layer 174, light emitting layer 176, electron transport layer 178, and electron injection layer 180, are formed in sequence by sputtering on the buffer layer 186 (FIG. 22). The buffer layer 186 and the inorganic EL layers may be selectively formed on the third subpixel 122-3, or may be formed on all the subpixels 122 as shown in FIG. 22, and then these components may be removed by etching in the first subpixel 122-1 and the second subpixel 122-2 (FIG. 23).

[0068] Subsequently, the first light emitting element 130-1 and the second light emitting element 130-2 are formed in the first subpixel 122-1 and the second subpixel 122-2, respectively, by the above-mentioned method. At this time, as shown in FIG. 24, the cathode 148 may be formed so as to be shared by all the subpixels 122. Therefore, when this manufacturing method is applied, the cathode 148 is continuous over all the subpixels 122 and exists in the same layer. Thereafter, the cap layer 150 and the protective film 160 may be formed as necessary according to the above-mentioned method (FIG. 25). The protective film 160 may also be formed so as to be continuous over all the subpixels 122 and exists in the same layer.

[0069] As described above, in the display device 100 according to one embodiment of the present invention, red and green organic electroluminescent elements and blue inorganic electroluminescent elements are provided in the sub-pixels 122, and the three primary colors of light are produced by these light-emitting elements to realize a display function. Therefore, the extremely high light-emitting efficiency of these light-emitting elements can be utilized in each sub-pixel 122. Therefore, by applying the embodiment of the present invention, it is possible to provide a display device 100 that is highly efficient and has low power consumption.

[0070] The above-described embodiments of the present invention may be combined as appropriate as long as they are not mutually inconsistent. In addition, a display device according to any of the embodiments may be combined as appropriate by a person skilled in the art to add or remove components or modify the design, or to add or omit steps or modify conditions, and the combination is included in the scope of the present invention as long as it includes the gist of the present invention.

[0071] Even if there are other effects and advantages different from those brought about by the aspects of each of the above-mentioned embodiments, those which are clear from the description in this specification or which 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]

[0072] 100: display device, 102: substrate, 104: scanning line driving circuit, 106: signal line driving circuit, 108: terminal, 110: connector, 112: display region, 114: undercoat, 116: planarization film, 118: partition wall, 120: pixel, 122: subpixel, 122-1: first subpixel, 122-2: second subpixel, 122-3: third subpixel, 124: pixel electrode, 126: second common wiring, 128: conductive wire, 130: light-emitting element, 130-1: first light-emitting element, 130-2: second light-emitting element, 130-3: third light-emitting element, 132: anode, 134: hole injection layer, 136: hole transport layer, 136-1: first hole transport layer, 136-2: second hole transport layer, 138: electron Block layer, 140: light emitting layer, 142: hole blocking layer, 144: electron transport layer, 146: electron injection layer, 148: cathode, 150: cap layer, 150-1: first cap layer, 150-2: second cap layer, 152: adhesive, 160: protective film, 170: anode, 172: hole injection layer, 174: hole transport layer, 176: light emitting layer, 176-1: high band gap layer, 176-2: low band gap layer, 178: electron transport layer, 180: electron injection layer, 182: cathode, 184: protective film, 186: buffer layer, 200: transistor, 202: semiconductor film, 204: gate insulating film, 206: gate electrode, 208: interlayer insulating film, 210: terminal, 212: terminal, 220: deposition mask

Claims

1. at least one pixel having a first subpixel, a second subpixel, and a third subpixel; the first subpixel and the second subpixel have red and green light-emitting organic electroluminescent elements, respectively; the third subpixel has a blue-emitting inorganic electroluminescent element; Each of the organic electroluminescent devices has an anode, a cathode, and an organic electroluminescent layer between the anode and the cathode; The display device, wherein the inorganic electroluminescent element has an anode, a cathode, and an inorganic electroluminescent layer electrically connected to the anode and the cathode.

2. The display device according to claim 1 , wherein the organic electroluminescent layer comprises a phosphorescent material or a thermally activated delayed fluorescent material.

3. The display device of claim 1 , wherein the inorganic electroluminescent layer comprises a gallium nitride based material.

4. The inorganic electroluminescent layer is a hole injection layer on the anode; a hole transport layer on the hole injection layer; a light-emitting layer on the hole transport layer; an electron transport layer on the light emitting layer; and an electron injection layer on the electron transport layer; The display of claim 1 , wherein the cathode is located on the electron injection layer.

5. The inorganic electroluminescent layer is a hole injection layer on the anode; a hole transport layer on the hole injection layer; a light-emitting layer on the hole transport layer; an electron transport layer on the light emitting layer; and an electron injection layer on the electron transport layer; The display device according to claim 1 , wherein the cathode is located below the electron injection layer and is exposed from the hole injection layer, the hole transport layer, the light emitting layer, and the electron transport layer in the vertical direction.

6. Each of the organic electroluminescent devices further comprises a capping layer on the cathode; The display device according to claim 1 , wherein the cap layer has the same structure between the organic electroluminescent element of the first sub-pixel and the organic electroluminescent element of the second sub-pixel.

7. Each of the organic electroluminescent devices further comprises a capping layer on the cathode; The display device according to claim 1 , wherein the cap layer has a different thickness between the organic electroluminescent element of the first sub-pixel and the organic electroluminescent element of the second sub-pixel.

8. The display device according to claim 1 , wherein each of the organic electroluminescent elements further comprises a protective film on the cathode.

9. the cathode of the organic electroluminescent element is continuous between the first subpixel and the second subpixel; The display device according to claim 1 , wherein the inorganic electroluminescent element is exposed from the cathode of the organic electroluminescent element.

10. the at least one pixel includes a plurality of pixels; The display device according to claim 1 , wherein the cathode of the organic electroluminescent element is provided in a stripe shape or a comb shape.

11. The area of ​​the inorganic electroluminescent device is 2×10 ２ μm ２ Above 2 x 10 ５ μm ２ 2. The display device according to claim 1, wherein:

12. each of the first subpixel, the second subpixel, and the third subpixel has a pixel circuit and a pixel electrode electrically connected to the pixel circuit; In the first subpixel and the second subpixel, the pixel electrode functions as the anode; The display device according to claim 1 , wherein the anode of the inorganic electroluminescent element is electrically connected to the pixel circuit via the pixel electrode.

13. forming at least one pixel on a substrate, the pixel including a first subpixel, a second subpixel, and a third subpixel; forming red-emitting and green-emitting organic electroluminescent elements in the first sub-pixel and the second sub-pixel, respectively; and forming a blue-emitting inorganic electroluminescent element in the third sub-pixel; Each of the organic electroluminescent devices includes an anode, a cathode, and an organic electroluminescent layer between the anode and the cathode; The inorganic electroluminescent element includes an anode, a cathode, and an inorganic electroluminescent layer electrically connected to the anode and the cathode.

14. The method according to claim 13 , wherein the organic electroluminescent layer comprises a phosphorescent material or a thermally activated delayed fluorescent material.

15. The method of claim 13 , wherein the inorganic electroluminescent layer comprises a gallium nitride based material.

16. each of the first subpixel, the second subpixel, and the third subpixel includes a pixel circuit and a pixel electrode electrically connected to the pixel circuit; The method according to claim 13 , wherein the inorganic electroluminescent device is formed by electrically connecting the anode and the pixel electrode.

17. each of the first subpixel, the second subpixel, and the third subpixel includes a pixel circuit and a pixel electrode electrically connected to the pixel circuit; The method according to claim 13 , wherein the organic electroluminescent element is formed by using the pixel electrode as the anode and laminating the organic electroluminescent layer and the cathode on the pixel electrode.

18. The method of claim 13 , wherein the inorganic electroluminescent element is formed after the organic electroluminescent element is formed.

19. The method according to claim 13 , wherein the cathode of the organic electroluminescent element is formed so as to be continuous between the first sub-pixel and the second sub-pixel and to expose the inorganic electroluminescent element.

20. the at least one pixel includes a plurality of pixels; The method according to claim 13 , wherein the cathode of the organic electroluminescent device is provided in a stripe shape or a comb shape.

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