Patent Application
20230105196
The present invention relates to a display device.
In recent years, a self-luminous display device using an electroluminescence (hereinafter “EL”) element employing an EL phenomenon, for example, has been developed as a display device instead of a liquid crystal display device.
The EL element has a configuration in which a light-emitting layer containing a light-emitting material is interposed between two electrodes. Subpixels including red color (R) EL elements, subpixels including green color (G) EL elements, and subpixels including blue color (B) EL elements arrayed on a substrate are selectively made to emit light with desired luminance by use of thin-film transistors (TFTs) to display intended images. Between every set of mutually-adjacent EL elements, a bank (partition) is disposed to define light-emitting regions of the subpixels. The light-emitting layer in each EL element is formed in an opening in the bank by use of a vapor deposition mask. Light generated in the light-emitting layer is extracted outside the display device from the opening of the bank.
In a display device described in PTL 1, a base having a forwardly tapered shape is formed on a substrate, with electrodes and light-emitting layers provided on an inclined face of the base. The light generated by the light-emitting layers is extracted from an opening provided above the base.
In a self-luminous display device, some of light generated by the light-emitting layers propagates and disappears in a lateral direction (direction parallel to the electrode) along an interface. Therefore, there is a problem in that about 20% of the light generated by the light-emitting layers is extracted outside the display device, resulting in a poor light extraction efficiency.
Further, in the prior art, there is room for improvement in achieving high luminance, or in the ability to form such pixels at high density while reducing a pixel area and making the pixels smaller.
An aspect of the present invention has been made in view of the problems described above, and an object thereof is to provide a display device that achieves high luminance or is capable of forming pixels at high density while reducing a pixel area and making the pixels smaller.
A display device according to an aspect of the present invention is a display device including a substrate, and a pixel provided on the substrate. The pixel includes a light-emitting portion including a plurality of light-emitting elements and configured to generate light, and a light-exiting portion adjacent to the light-emitting portion. The light-exiting portion includes a first light-reflecting portion provided on an incline on the substrate and configured to receive and reflect the light from the light-emitting portion, and an opening configured to emit the light reflected by the first light-reflecting portion to the outside. At least some of the plurality of light-emitting elements are formed by being layered.
Further, in the display device according to an aspect of the present invention, the light-emitting portion includes a red light-emitting element configured to emit red light, a green light-emitting element configured to emit green light, and a blue light-emitting element configured to emit blue light.
In the display device according to an aspect of the present invention, in the light-emitting portion, the blue light-emitting element has a light-emitting area larger than that of the red light-emitting element and the green light-emitting element.
In the display device according to an aspect of the present invention, each of the plurality of light-emitting elements includes a first electrode, a light-emitting layer, and a second electrode in this order from the substrate side.
In the display device according to an aspect of the present invention, the light-emitting portion includes a light absorption layer in an upper layer overlying the second electrode.
In the display device according to an aspect of the present invention, at least one second light-reflecting portion is provided between the substrate and the first electrode, between the first electrode and the light-emitting layer, between the light-emitting layer and the second electrode, and between the second electrode and the light absorption layer, and some of light generated by the light-emitting layer is reflected by the second light-reflecting portion and guided to the light-exiting portion.
In the display device according to an aspect of the present invention, the second light-reflecting portion has a refractive index lower than that of the light-emitting layer.
In the display device according to an aspect of the present invention, the second light-reflecting portion is constituted by a plurality of layers, the plurality of layers are provided so that a refractive index decreases in order from a layer closest to the light-emitting layer to a layer farthest from the light-emitting layer, and the layer closest to the light-emitting layer has a refractive index lower than that of the light-emitting layer.
In the display device according to an aspect of the present invention, the second light-reflecting portion includes a metal layer formed of a metal material.
In the display device according to an aspect of the present invention, the second light-reflecting portion includes a gas layer formed of a gas.
In the display device according to an aspect of the present invention, the second light-reflecting portion has unevenness on a surface facing the light-emitting layer.
In the display device according to an aspect of the present invention, the light absorption layer has unevenness on a surface on a side opposite to the light-emitting layer.
In the display device according to an aspect of the present invention, the opening has unevenness formed by shaving a waveguide on an opening face.
In the display device according to an aspect of the present invention, the light-exiting portion is disposed surrounding the light-emitting portion.
In the display device according to an aspect of the present invention, the opening does not overlap the light-emitting layer in a plan view.
According to an aspect of the present invention, it is possible to provide a display device that achieves high luminance or is capable of forming pixels at high density while reducing a pixel area and making the pixels smaller.
Hereinafter, a “lower layer” refers to a layer formed in a process before the layer being compared, and an “upper layer” refers to a layer formed in a process after the layer being compared.
Embodiments of the disclosure will be described with reference to
The present embodiment will be described with reference to
As illustrated in
Further, although two light-exiting portions 104 are illustrated in
As illustrated in
Each of the light-emitting layers may include a function layer such as an electron transport layer (ETL) and a hole transport layer (HTL).
Hereinafter, unless otherwise specified, the light-emitting layer 106r of R, the light-emitting layer 106g of G, and the light-emitting layer 106b of B may be collectively referred to as a light-emitting layer 106.
As illustrated in
Further, the light-exiting portion 104 includes the first light-reflecting portion 109 provided on an incline on the substrate 101 and configured to receive and reflect the light from the light-emitting portion 103, and the opening 111 configured to emit the light reflected by the first light-reflecting portion 109 to the outside. Further, as illustrated in
As illustrated in
Further, as illustrated in
A bank 117 is formed between adjacent pixels. The bank 117 includes an inclined face inclined relative to the substrate 101, and the first light-reflecting portion 109 is formed on the inclined face of the bank 117. The first light-reflecting portion 109 is preferably made of a material having high reflectivity, such as a metal such as silver or aluminum, for example. The first light-reflecting portion 109 is formed in a layered manner, for example.
A light absorption layer 108 absorbs external light, and thus can prevent external light reflection. Accordingly, the display device 10 can ensure good visibility even without an anti-reflective film (a circular polarizer composed of a linear polarizer and a ¼λ plate or the like) being provided.
In the display device 10, the light-emitting portion 103 including the light-emitting layer 106 and the light absorption layer 108 is responsible for light emission, and the light-exiting portion 104 including the opening 111 emits light generated by the light-emitting layer 106 to outside of the display device 10 by utilizing reflection. Further, the external light is absorbed by the light absorption layer 108.
As described above,
The light-emitting portion 103 included in each of the pixels of the display device 10 and each light-emitting layer included in the light-emitting portion 103 are formed so as to have a quadrangular shape in a plan view, for example, as illustrated in
The light-emitting portion 103 and each light-emitting layer included in the light-emitting portion 103 may be formed in various shapes other than a quadrangular shape, such as a triangular shape. Further, the openings 111 may be formed in various positions other than those illustrated in
The display device 10 according to the present embodiment is a structure for laterally extracting light, and can efficiently extract the light generated by the light-emitting layer 106.
Further, because the light-emitting elements are configured to be layered, an area of the light-emitting layer can be widened, making it possible to achieve high luminance. Alternatively, the light-emitting elements may be configured to be layered, making it possible to reduce a pixel area without significantly lowering the luminance of one pixel, achieve an effect such as size reduction, and thus form the pixels at high density.
The display device 10 in the present embodiment overlaps the light-emitting elements (light-emitting layer 106r of R, light-emitting layer 106g of G, and light-emitting layer 106b of B), making it possible to increase an area of the light-emitting element (light-emitting layer 106b of B in the example illustrated in
The display device 10 according to the present embodiment will be described in more detail below.
The substrate 101 is not particularly limited, and a known support substrate including, for example, an insulating substrate, a barrier layer, or a thin film transistor (TFT) can be used, for example.
The insulating substrate is not particularly limited as long as it has insulating properties. The insulating substrate used may be one of a variety of known insulating substrates, such as transparent substrates such as inorganic material substrates including a glass substrate and a quartz substrate, for example; plastic substrates such as substrates made from polyethylene terephthalate or polyimide resin, for example; and non-transparent substrates such as semiconductor substrates including silicon wafers, substrates obtained by coating an insulating material on a surface of a metal substrate, and substrates obtained by insulation-treating a surface of a metal substrate, for example.
The barrier layer is a layer that inhibits foreign matters such as water and oxygen from entering the TFT layer, and can be formed by a silicon oxide film, a silicon nitride film, or a silicon oxynitride film, or by a layered film of these, formed by chemical vapor deposition (CVD), for example.
The TFT layer includes a semiconductor film, an inorganic insulating film (gate insulating film) in an upper layer overlying the semiconductor film, a gate electrode and a gate wiring line in an upper layer overlying the inorganic insulating film, an inorganic insulating film in an upper layer overlying the gate electrode and the gate wiring line, a capacitance electrode in an upper layer overlying the inorganic insulating film, an inorganic insulating film in an upper layer overlying the capacitance electrode, a source wiring line in an upper layer overlying the inorganic insulating film, and a flattening film (interlayer insulating film) in an upper layer overlying the source wiring line.
The semiconductor film is constituted of, for example, a low-temperature polysilicon (LTPS) or an oxide semiconductor (for example, an In—Ga—Zn—O-based semiconductor), and a transistor (TFT) is configured to include the semiconductor film and the gate electrode. The transistor may have a top gate structure or may have a bottom gate structure.
The gate electrode, the gate wiring line, the capacitance electrode, and the source wiring line are each composed of a single layer film or a layered film of a metal including at least one of aluminum, tungsten, molybdenum, tantalum, chromium, titanium, and copper, for example.
The inorganic insulating film can be formed of, for example, a silicon oxide (SiOx) film or a silicon nitride (SiNx) film, or a layered film of these, formed by CVD. The flattening film may be formed of coatable organic materials such as polyimide and acrylic, for example.
As described above, the pixel 102 includes the light-emitting portion 103 and the light-exiting portion 104. The pixel 102 may be an organic light-emitting diode (OLED), or may be an inorganic light-emitting diode, or may be a quantum dot light-emitting diode (QLED). Further, the pixel 102 may be a micro light-emitting diode (LED). A circuit that controls the pixel 102 is formed in the TFT layer of the substrate 101.
As illustrated in
Further, as illustrated in
Although only partially illustrated, as illustrated in
The light-exiting portion 104 includes a region with at least some of the pixel 102 overlapping the opening 111 in a plan view and not covered by the light absorption layer 108, and includes the first light-reflecting portion 109 provided on an incline on the substrate 101, and the opening 111 provided in the light absorption layer 108.
The light-exiting portion 104 may further include the waveguide (transparent layer) 110 provided so as to further guide the light reflected by the first light-reflecting portion 109 to the opening 111, as necessary. Further, although the waveguide 110 and the light-emitting portion 103 are adjacent to each other in
The first electrode 105, which is a lower layer electrode, is formed for each light-emitting element, and is connected to the corresponding TFT via a contact hole (not illustrated) provided in a lower layer underlying the first electrode 105, for example.
The second electrode 107, which is an upper layer electrode, is formed for each light-emitting element, and is connected to a wiring line or the like via a contact hole (not illustrated) provided in an upper layer overlying the second electrode 107, for example.
Further, for example, the first electrodes 105 of each light-emitting element, or the second electrodes 107 of each light-emitting element, or the first electrode 105 of one light-emitting element and the second electrode 107 of another light-emitting element may be electrically connected to each other to form a common electrode.
The first electrode 105 and the second electrode 107 may be transparent electrodes that use a transparent electrode material, or may be reflective electrodes that use a reflective electrode material. At least one of the first electrode 105 and the second electrode 107 is preferably a transparent electrode as such a configuration increases the light extraction efficiency. Here, a refractive index of the transparent electrode is preferably lower than a refractive index of the light-emitting layer 106.
At least one of the first electrode 105 and the second electrode 107 is a transparent electrode having a refractive index lower than that of the light-emitting layer 106, and thus some of the light generated by the light-emitting layer 106 is totally reflected at an interface between the light-emitting layer 106 and the transparent electrode, propagates in the lateral direction, reaches the light-exiting portion 104, and exits from the opening 111.
Furthermore, a refractive index of the second light-reflecting portion 122 is set lower than those of the transparent electrodes 105, 107, and thus the light generated by total reflection at an interface between the transparent electrodes 105, 107 and the second light-reflecting portion 122 is also guided to an end face of the light-emitting layer 106.
The total reflection occurring at the interface between the light-emitting layer 106 and the transparent electrodes 105, 107, or the total reflection occurring at the interface between the transparent electrodes and the second light-reflecting portion 122 has superior reflection efficiency compared to metal reflection, allowing light to be propagated substantially without attenuation, and thus making it possible to increase the light extraction efficiency.
The first electrode 105 serving as the lower layer electrode, and the second electrode 107 serving as the upper layer electrode, serve as a pair of electrodes, with one functioning as an anode electrode and the other functioning as a cathode electrode. The first electrode 105 may be the cathode electrode, and the second electrode 107 may be the anode electrode. Conversely, the first electrode 105 may be the anode electrode, and the second electrode 107 may be the cathode electrode. In a case in which the anode electrode and cathode electrode are reversed, the layering order or carrier mobility (carrier transport properties, that is, hole transport properties and electron transport properties) of each function layer described below are reversed accordingly.
In a case in which the pixel 102 is an OLED, positive holes and electrons recombine inside the light-emitting layer 106 in response to a drive current between the anode electrode and the cathode electrode, and light is emitted when the excitons generated in this manner transition to a ground state.
In a case where the pixel 102 is a QLED, positive holes and electrons recombine inside the light-emitting layer 106 in response to a drive current between the anode electrode and the cathode electrode, and light (fluorescence) is emitted when the excitons generated in this manner transition from the conduction band of the quantum dot to the valence band.
Electrode materials are not particularly limited, and known electrode materials may be employed.
Examples of the transparent electrode material include indium tin oxide (ITO), tin oxide (SnO2), indium zinc oxide (IZO), and gallium-added zinc oxide (GZO).
Examples of the reflective electrode material include a black electrode material such as tantalum (Ta) or carbon (C), Al, Ag, gold (Au), Al—Li alloy, Al-neodymium (Nd) alloy, and Al-silicon (Si) alloy.
The light-emitting layer 106 is a layer having a function of emitting light by causing the holes (positive holes) injected from the anode electrode side and the electrons injected from the cathode electrode side to recombine so as to emit light, and utilizes quantum dots, for example, for light emission.
Various known types of light-emitting material may be employed as the material of the light-emitting layer (namely, a light-emitting substance), and the material is not limited to a specific material. A light-emitting material having a high luminous efficiency is preferably employed therefor, such as a low molecular weight fluorescent colorant or a metal complex.
Examples of the light-emitting material include anthracene, naphthalene, indene, phenanthrene, pyrene, naphthacene, triphenylene, perylene, picene, fluoranthene, acephenanthrylene, pentaphene, pentacene, coronene, butadiene, coumarin, acridine, stilbene, and derivatives thereof; a tris(8-quinolinolato)aluminum complex; a bis(benzoquinolinolato) beryllium complex; a tri(dibenzoylmethyl)phenanthroline europium complex; ditoluylvinylbiphenyl; and nanocrystals containing phosphors such as InP and CdSe.
A layer thickness of the light-emitting layer 106 is set as appropriate according to the light-emitting material, is not limited to a specific value, and is, for example, from about several nm to about several hundred nm.
Further, the light-emitting layer 106 may have a single layer configuration or may have a multilayer configuration including a plurality of layers.
As described above, the light-emitting portion 102 may include further function layers between the first electrode 105 and the light-emitting layer 106 and between the light-emitting layer 106 and the second electrode 107, as necessary.
Typical examples of such a function layer include layers such as a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer.
The hole injection layer is a layer including a hole injection material and having the function of increasing the hole injection efficiency from the anode electrode to the light-emitting layer 106. Further, the hole transport layer is a layer including a hole injection material and having the function of increasing the hole transport efficiency to the light-emitting layer 106.
The electron injection layer is a layer including an electron injection and having the function of increasing the electron injection efficiency from the cathode electrode to the light-emitting layer 106. The electron transport layer is a layer including an electron transport material and having the function of increasing the electron transport efficiency to the light-emitting layer 106.
The hole injection layer and the hole transport layer may be formed as mutually independent layers, or may be integrated together as a hole injection-cum-transport layer. Similarly, the electron injection layer and the electron transport layer may be formed as mutually independent layers, or may be integrated together as an electron injection-cum-transport layer.
Only one of the hole injection layer and the hole transport layer may be provided. Similarly, only one of the electron injection layer and the electron transport layer may be provided.
Further, other than the function layer stated above, a carrier block layer, an intermediate layer, or the like may be provided.
Note that the material of these function layers and the like is also not limited, and conventional materials may be employed as each such layers. Further, these function layers and the like are not essential layers, and layer thicknesses thereof are not limited to specific values. Thus, the description thereof is omitted in the present embodiment.
The light absorption layer 108 is a layer for absorbing external light and suppressing external light reflection.
Examples of the resin forming the light absorption layer 108 include a pigment-containing resin such as carbon black generally used for a black matrix.
The light absorption layer 108 is formed so as to include the opening 111 on the second electrode 107. Here, a portion where the opening 111 is provided corresponds to the light-exiting portion 104, and the other portion corresponds to the light-emitting portion 103.
The opening 111 may overlap or may not overlap the light-emitting layer 106, which is a lower layer underlying the light absorption layer 108, and the first electrode 105 and the second electrode 107, in a plan view. More preferably, the opening 111 is provided so as not to overlap the light-emitting layer 106, the first electrode 105, and the second electrode 107, in a plan view.
According to this configuration, the light reflected by the first light-reflecting portion 109 can be extracted to the outside from the opening 111 without passing through the light-emitting layer 106, the first electrode 105, and the second electrode 107, which have different refractive indices from each other, thereby making the extraction efficiency even higher.
An area of the opening 111 can be set as appropriate in accordance with the desired light extraction efficiency and suppression effect of the external light reflection.
By adjusting an inclination angle θ of the first light-reflecting portion 109 and an area ratio between the opening 111 and the light-emitting portion 103 in accordance with the size of the light-emitting element and the thickness of the pixel 102, it is possible to suppress the external light reflection without providing an anti-reflective film while ensuring favorable light extraction efficiency.
The first light-reflecting portion 109 is a layer provided on the substrate 101 that is inclined at the inclination angle θ in the region of the light-exiting portion 104.
The inclination angle θ can be set as appropriate so as to guide the light propagating from the light-emitting portion 103 to the opening 111.
By setting the inclination angle θ to 450 or less, preferably from 30° to 45°, for example, it is possible to extract the light generated by the light-emitting portion 103 more efficiently. On the other hand, by setting the inclination angle θ to greater than 45° for example, it is possible to reduce the area of the opening 111, and thus more reliably suppress the external light reflection. Note that the upper limit of the inclination angle is not particularly limited, but can be exemplified as less than 90°, for example.
Further, the inclined face of the first light-reflecting portion 109 may be constituted by one flat face or a combination of a plurality of flat faces, or may be constituted by one curved face or a combination of a plurality of curved faces, or may be constituted by a combination of one or a plurality of flat faces and one or a plurality of curved faces.
Note that the inclination angle θ refers to the angle at which a line segment connecting both end portions of the inclined face of the first light-reflecting portion 109 intersects the substrate 101 in a side view.
The first light-reflecting portion 109 can be formed of a material having high reflectivity such as, for example, a metal such as silver or aluminum.
The second light-reflecting portion 122 may be formed between each light-emitting element as illustrated in
However, a quantity and a position of the second light-reflecting portion are not limited thereto. That is, the second light-reflecting portion may be configured to be positioned between at least one of the substrate 101 and the first electrode 105, the first electrode 105 and the light-emitting layer 106b of B, the light-emitting layer 106 and the second electrode 107, and the second electrode 107 and the light absorption layer 108. Further, the second light-reflecting portion may have a single layer configuration, or may have a multilayer configuration formed by layering a plurality of layers.
In one aspect of the present invention, the at least one second light-reflecting portion is preferably a layer formed of a transparent resin as such a configuration increases the light extraction efficiency. Here, the refractive index of the second light-reflecting portion is preferably lower than the refractive index of the light-emitting layer 106.
The following describes, on the basis of
As illustrated (in
Here, to achieve total reflection, the first electrode 105, the second electrode 107, and the second light-reflecting portion 122 are preferably layered so that the refractive index decreases from the layer closest to the light-emitting layer 106 toward the layer farthest from the light-emitting layer 106.
For example, the refractive index of the second light-reflecting portion 122 positioned between the first electrode 105 and the substrate 101 is preferably lower than the refractive index of the first electrode 105. Similarly, the refractive index of the second light-reflecting portion 122 positioned between the second electrode 107 and the light absorption layer 108 is preferably lower than the refractive index of the second electrode 107.
With such a configuration, as illustrated in
More specifically, in a preferred aspect of the present embodiment, the refractive index of the light-emitting layer 106 is 2, the second electrode 107 is composed of indium tin oxide having a refractive index of 2, and the second light-reflecting portion 122 is formed of polymethyl methacrylate having a refractive index of 1.5. At this time, the critical angle θ1 is 49°.
Accordingly, of the light generated by the light-emitting layer 106, light incident on the interface between the second electrode 107 and the second light-reflecting portion 122 at an angle equal to or greater than 490 (approximately 46%) is totally reflected at this interface between layers and propagates in the lateral direction.
On the other hand, light incident at an angle of less than 49° travels in the second light-reflecting portion 122, reaches the light absorption layer 108, and is absorbed. In this aspect, approximately 46% of the light generated by the light-emitting layer 106 can be extracted from the opening 111 by total reflection.
Next, on the basis of
In a case in which the second light-reflecting portion has a multilayer configuration formed by layering a plurality of layers, the plurality of layers are layered so that the refractive index decreases from the layer closest to the light-emitting layer 106 toward the layer farthest from the light-emitting layer 106, and the refractive index of the layer closest to the light-emitting layer 106 is preferably lower than that of the light-emitting layer 106.
For example,
With such a configuration, of the light generated by the light-emitting layer 106, light incident on an interface between the second electrode 107 and the first layer 122a at an angle equal to or greater than a critical angle θ2 is totally reflected at this interface and propagates in the lateral direction. Further, at an interface between the first layer 122a and the second layer 122b, light incident at an angle equal to or greater than a critical angle θ3 is totally reflected at this interface and propagates in the lateral direction.
More specifically, in a preferred aspect of the present embodiment, the refractive index of the light-emitting layer 106 is 2, the second electrode 107 is composed of indium tin oxide having a refractive index of 2, the first layer 122a is formed of polymethyl methacrylate having a refractive index of 1.7, and the second layer 122b is formed of a polymethyl methacrylate having a refractive index of 1.5. At this time, the critical angle θ2 is 58°, and the critical angle θ3 is 62°.
Accordingly, of the light generated by the light-emitting layer 106, light incident on the interface between the second electrode 107 and the first layer 122a at an angle equal to or greater than 580 (approximately 35%) is totally reflected at the interface between the layers and propagates in the lateral direction.
On the other hand, light incident at an angle of less than 58° travels in the first layer 122a and reaches the interface with the second layer 122b. Here, the light incident on the interface at an angle of 62° or greater (approximately 20%) is totally reflected at the interface between the layers and propagates in the lateral direction. In this aspect, approximately 55% of the light generated by the light-emitting layer 106 can be guided to the light-exiting portion 104 by total reflection.
By increasing the number of layers of the second light-reflecting portion 122, it is possible to further enhance the light extraction efficiency.
The second light-reflecting portion 122 may be formed of a plurality of layers throughout the light-emitting portion 103, or a plurality of layers may be formed in a portion of the light-emitting portion 103. The number of layers of the second light-reflecting portion 122 may be different in a portion of the light-emitting portion 103, or the materials constituting each layer may be different.
In
On the basis of
Furthermore, by changing the pixel area, it is possible to accommodate the R and G light-emitting elements in the B light-emitting element area, and only layer the two layers of the light-emitting layer 106b of B and the light-emitting layers 106r and 106g of R and G.
A second embodiment of the present invention will now be described with reference to
As illustrated in
In the present embodiment, as illustrated in
In
In the display device 20, the first layer 122c of the second light-reflecting portion 122A is formed in a lower layer underlying the first electrode 105 of each light-emitting element, and the second layer 122d is formed in a lower layer underlying each first layer 122c. The second layer 122d can be formed of a metal, for example. Even in a case in which the second layer 122d is formed of a metal having electrical conductivity, leakage between electrodes can be prevented as long as the transparent layer 110 and the first layer 122c adjacent to the second layer 122d have no electrical conductivity.
Each second layer 122d may be provided with unevenness on a surface facing the light-emitting layer 106. With the second layer 122d provided with unevenness on the surface facing the light-emitting layer 106, light generated perpendicular to a light-emitting face of the light-emitting layer 106 can be reflected in an obliquely lateral direction. This makes it possible to increase the light that can be totally reflected in each light-emitting element.
The second layer 122d having such unevenness can be formed by, for example, providing a concave-convex structure on the underlayer by using a nanoprint technique and then vapor-depositing a reflective film of a metal thereon.
Further, the light absorption layer 108a is provided with unevenness on a surface on a side opposite to the light-emitting layer 106. By forming unevenness on the light absorption layer 108a, it is possible to scatter the external light and suppress external light reflection.
Further, such unevenness can be formed by, for example, shaving a surface of the light absorption layer 108a.
Further, unevenness is formed on an opening face of the opening 111a. By forming unevenness on the opening 111a, it is possible to diffuse the emitted light and widen a viewing angle. Such unevenness can be formed by, for example, shaving a surface of the waveguide 110.
In the display device 20 according to the second embodiment, as in the display device 10 according to first embodiment, total reflection can be utilized to increase the light extraction efficiency and, by scattering the external light, external light reflection can be suppressed to widen the viewing angle.
A third embodiment of the present invention will now be described with reference to
As illustrated in
In the display device 30, light emitted from the light-emitting layer (light-emitting layer 106b in
In the display device 30, light that travels in the perpendicular direction from the light-emitting layer or the like and is thus not totally reflected and is less likely to be guided to the light-exiting portion 104b can be removed to the outside via the anti-reflective film 114. Further, the anti-reflective film 114 can prevent external light reflection.
In the display device 30 according to the third embodiment, the same effects as those of the display device 10 according to the first embodiment can be achieved and, in addition, the light of the light-emitting layer 106b of B generated perpendicular to the light-emitting face can be output as is.
A fourth embodiment of the present invention will now be described with reference to
The display device 40 includes the light-emitting portion 103c in which the vertical relationship between the light-emitting element including the light-emitting layer 106b, the light-emitting element including the light-emitting layer 106g, and the light-emitting element including the light-emitting layer 106r in the light-emitting portion 103b of the display device 30 of the third embodiment is reversed.
In the display device 40, light emitted from the light-emitting layers (light-emitting layer 106g and light-emitting layer 106r in
In the display device 40 according to the fourth embodiment, as in the display device 10 according to the first embodiment, total reflection can be utilized to increase the light extraction efficiency, and the light generated vertically above the light-emitting face from the light-emitting layer 106g of G and the light-emitting layer 106r of R can be output to the outside as is.
A fifth embodiment of the present invention will now be described with reference to
As illustrated in
Specifically, the common electrode 116 is formed between the light-emitting layer 106b of B formed in an upper layer and the light-emitting layer 106g of G as well as the light-emitting layer 106r of R formed in a lower layer. The common electrode 116 serves as the first electrode of the light-emitting element including the light-emitting layer 106b, and also serves as the second electrode of the light-emitting element including the light-emitting layer 106g and the light-emitting element including the light-emitting layer 106g. According to this configuration, the electrode required for each color in the conventional layered structure is common to all colors, and thus the layered structure can be simplified. The common electrode 116 may be a transparent electrode or a metal electrode, or a metal electrode may be interposed between transparent electrodes.
The second light-reflecting portion may be formed of any material capable of reflecting light at an interface with the adjacent layer. Examples of such materials include transparent resins such as polymethyl methacrylate having various refractive indices. The second light-reflecting portion may be a metal layer formed of a metal material such as silver or aluminum. The second light-reflecting portion may be a gas layer formed by a gas such as the atmosphere.
For example, the second light-reflecting portion may be a layer formed of a transparent resin, a metal layer, a gas layer, or a combination of these.
However, in a case in which the second light-reflecting portion is between the first electrode 105 and the light-emitting layer 106b of B and/or between the light-emitting layer 106b of B and the second electrode 107, the second light-reflecting portion is formed of a material having electrical conductivity.
In a preferred aspect of the present invention, the second light-reflecting portion may have a multilayer configuration including, for example, a transparent layer made of a transparent resin positioned on the light-emitting layer 106b of B side and a metal layer positioned on the side opposite to the light-emitting layer 106b of B.
Note that the various electrodes and the banks (partitions) can use materials commonly used in OLEDs and QLEDs.
The display device 50 according to the fifth embodiment can also achieve the same effects as those of the display device 10 according to the first embodiment.
First, as illustrated in
Subsequently, as illustrated in
Subsequently, as illustrated in
Subsequently, as illustrated in
Lastly, as illustrated in
Further, in the example of
By the process described above, the display device 50 according to the present embodiment is obtained.
As described above, the second light-reflecting portion may be partially formed as a gas layer constituted by a gas. In the following, a method for manufacturing a display device 60, in which a gas layer is formed, will be described.
When formed, the gas layer can be fabricated by, for example, separately creating an upper constituent element and a lower constituent element and then combining the upper constituent element and the lower constituent element.
A display device includes a substrate, and a pixel provided on the substrate. The pixel includes a light-emitting portion including a plurality of light-emitting elements to generate light, and a light-exiting portion adjacent to the light-emitting portion. The light-exiting portion includes a first light-reflecting portion provided on an incline on the substrate and configured to receive and reflect the light from the light-emitting portion, and an opening configured to emit the light reflected by the first light-reflecting portion to the outside. At least some of the plurality of light-emitting elements are formed by being layered.
In the display device according to the first aspect, the light-emitting portion includes a red light-emitting element configured to emit red light, a green light-emitting element configured to emit green light, and a blue light-emitting element configured to emit blue light, for example.
In the display device according to the second aspect, in the light-emitting portion, the blue light-emitting element has a light-emitting area larger than that of the red light-emitting element and the green light-emitting element, for example.
In the display device according to any one of the first to third aspects, each of the plurality of light-emitting elements includes a first electrode, a light-emitting layer, and a second electrode in this order from the substrate side, for example.
In the display device according to the fourth aspect, the light-emitting portion includes a light absorption layer in an upper layer overlying the second electrode, for example.
In the display device according to the fifth aspect, at least one second light-reflecting portion is provided between the substrate and the first electrode, between the first electrode and the light-emitting layer, between the light-emitting layer and the second electrode, and between the second electrode and the light absorption layer, and some of light generated by the light-emitting layer is reflected by the second light-reflecting portion and guided to the light-exiting portion, for example.
In the display device according to the sixth aspect, the second light-reflecting portion has a refractive index lower than that of the light-emitting layer, for example.
In the display device according to the sixth aspect, the second light-reflecting portion is constituted by a plurality of layers, the plurality of layers are provided so that a refractive index decreases in order from a layer closest to the light-emitting layer to a layer farthest from the light-emitting layer, and the layer closest to the light-emitting layer has a refractive index lower than that of the light-emitting layer, for example.
In the display device according to any one of the sixth to eighth aspects, the second light-reflecting portion includes a metal layer formed of a metal material, for example.
In the display device according to any one of the sixth to ninth aspects, the second light-reflecting portion includes a gas layer formed of a gas, for example.
In the display device according to any one of the sixth to tenth aspects, the second light-reflecting portion has unevenness on a surface facing the light-emitting layer, for example.
In the display device according to any one of the sixth to eleventh aspects, the light absorption layer has unevenness on a surface on a side opposite to the light-emitting layer, for example.
In the display device according to any one of the first to twelfth aspects, the opening has unevenness formed by shaving a waveguide on an opening face, for example.
In the display device according to any one of the first to thirteenth aspects, the light-exiting portion is disposed surrounding the light-emitting portion, for example.
In the display device according to any one of the fourth to twelfth aspects, the opening does not overlap the light-emitting layer in a plan view, for example.
The present invention is not limited to the embodiments described above, and embodiments obtained by appropriately combining technical approaches disclosed in the different embodiments also fall within the technical scope of the present invention. Furthermore, novel technical features can be formed by combining the technical approaches disclosed in each of the embodiments.
The display device according to the present embodiment is not particularly limited as long as the display device is a display panel provided with display elements such as light-emitting elements. The display element is a display element in which luminance and transmittance are controlled by an electric current, and examples of the electric current-controlled display element include an organic electro-luminescence (EL) display provided with an organic light-emitting diode (OLED), an EL display such as an inorganic EL display provided with an inorganic light-emitting diode, and a quantum dot light-emitting diode (QLED) display provided with a QLED.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/008760 | 3/2/2020 | WO |
