Light emitting diode and display device using the same

Abstract

Disclosed are a light emitting diode and a display device using the same. The organic light emitting diode includes: a first electrode; a first organic layer disposed on the first electrode and having a first refractive index; a light emitting layer disposed on the first organic layer and having a second refractive index; a second organic layer disposed on the light emitting layer and having a third refractive index; and a second electrode disposed on the second organic layer, in which the first refractive index is equal to or greater than the second refractive index, the second refractive index being greater than the third refractive index.

Description

[0001] Cross - reference to related applications

[0002] This application claims the benefit of Korean Patent Application No. 10 - 2023 - 0169339, filed on November 29, 2023, which is hereby incorporated herein by reference in its entirety as if fully set forth herein. Technical field

[0003] The present invention relates to a light - emitting diode and a display device using the light - emitting diode. Background art

[0004] With the development of the information society, the demand for display devices for displaying images has increased in various forms. Accordingly, various display devices such as liquid crystal displays (LCDs), plasma display panels (PDPs), and organic light - emitting displays (OLEDs) have recently been used.

[0005] Among these display devices, compared with a liquid crystal display (LCD), an organic light - emitting display device is a self - emissive type, has excellent viewing angles and contrast ratios, and does not require a separate backlight, so it can be light and thin, and the power consumption is advantageous. In addition, the organic light - emitting display device has the advantages of being able to drive at a low DC voltage, having a fast response speed, and particularly having a low manufacturing cost.

[0006] An organic light - emitting display device has a structure in which an organic light - emitting diode including a light - emitting layer is disposed between a cathode for injecting electrons and an anode for injecting holes. The organic light - emitting display device is a display device that adopts the principle that when electrons generated at the cathode and holes generated at the anode are injected into the light - emitting layer, the injected electrons and holes combine to generate excitons, and the generated excitons drop from the excited state to the ground state, thereby emitting light.

[0007] In an organic light - emitting display device, the brightness of light emitted while forming a predetermined angle with the normal direction of the light - emitting surface is lower than that of light emitted in the normal direction of the light - emitting surface. That is, the brightness is different when the display device is viewed from the side and when it is viewed from the front. In this case, there is a problem that the image quality when viewed from the front and when viewed from the side is different or the color reproduction rate is reduced. Summary of the invention

[0008] In view of the above problems, the present invention has been made. An object of the present invention is to provide a light-emitting diode and a display device including the light-emitting diode. The light-emitting diode includes: a first organic layer disposed on a first electrode and in contact with an upper surface of the first electrode; a light-emitting layer disposed on the first organic layer; and a second organic layer disposed under a second electrode, wherein a first refractive index of the first organic layer is greater than a third refractive index of the second organic layer, thereby increasing the brightness of the side surface.

[0009] According to an aspect of the present invention, the above and other objects can be achieved by providing an organic light-emitting diode including: a first electrode; a first organic layer disposed on the first electrode and having a first refractive index; a light-emitting layer disposed on the first organic layer and having a second refractive index; a second organic layer disposed on the light-emitting layer and having a third refractive index; and a second electrode disposed on the second organic layer, wherein the first refractive index is equal to or greater than the second refractive index, and the second refractive index is greater than the third refractive index.

[0010] In addition, the above and other objects can be achieved by providing a display device including: a substrate including a first pixel region, a second pixel region, and a third pixel region; and an organic light-emitting diode disposed in the first pixel region, the second pixel region, and the third pixel region, wherein any one of the organic light-emitting diodes disposed in each pixel region includes: a first electrode; a second electrode disposed on the first electrode; a first organic layer disposed to be in contact with an upper surface of the first electrode; a light-emitting layer disposed on the first organic layer; and a second organic layer disposed on the light-emitting layer and disposed to be in contact with a lower surface of the second electrode, wherein a first refractive index of the first organic layer is equal to or greater than a second refractive index of the light-emitting layer, and the second refractive index of the light-emitting layer is greater than a third refractive index of the second organic layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above and other objects, features, and other advantages of the present invention will be more clearly understood from the following detailed description in conjunction with the accompanying drawings, in which:

[0012] Figure 1 is a schematic diagram of a display device according to an embodiment of the present invention.

[0013] Figure 2 is a cross-sectional view of a display device according to an embodiment of the present invention. In this case, Figure 2 corresponds to Figure 1 section I-I'.

[0014] Figure 3It is a schematic diagram showing a first pixel region, a second pixel region, and a third pixel region of an organic light-emitting diode according to an embodiment of the present invention.

[0015] Figure 4 It is a cross-sectional view schematically illustrating a part of an organic light-emitting diode according to an embodiment of the present invention.

[0016] Figure 5 It is a schematic cross-sectional view illustrating a part of an organic light-emitting diode according to another embodiment of the present invention.

[0017] Figure 6 It is a cross-sectional view schematically illustrating a part of an organic light-emitting diode according to another embodiment of the present invention.

[0018] Figure 7 It is a schematic cross-sectional view illustrating a part of an organic light-emitting diode according to another embodiment of the present invention.

[0019] Figure 8 It is a schematic perspective view illustrating a part of an organic light-emitting diode according to another embodiment of the present invention.

[0020] Figure 9 It is a graph showing the luminance based on the viewing angle of an organic light-emitting diode according to an embodiment of the present invention. Detailed Embodiments

[0021] The advantages, features, and implementation methods of the present invention will be clarified by the following embodiments described with reference to the accompanying drawings. However, the present invention can be implemented in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those of ordinary skill in the art. In addition, the present invention is only defined by the scope of the claims.

[0022] The shapes, sizes, ratios, angles, and quantities disclosed in the drawings used to describe the embodiments of the present invention are merely examples. Therefore, the present invention is not limited to the illustrated details. Like reference numerals refer to like elements throughout. In the following description, when it is determined that a detailed description of related known functions or configurations would unnecessarily obscure the gist of the present invention, such detailed description will be omitted.

[0023] In cases where "comprising", "having", and "including" described in the present invention are used, other parts may be added unless "only" is used. Terms in the singular form may include the plural form unless otherwise specified.

[0024] When interpreting an element, the element is interpreted as including an error range, although not explicitly described.

[0025] When describing a positional relationship, for example, when the positional order is described as "on", "above", "below", "underneath", and "after", cases where there is no contact therebetween may be included, unless "exactly" or "directly" is used.

[0026] If it is mentioned that a first element is located on a second element, it does not necessarily mean that the first element is located above the second element in the figure. The upper and lower parts of the object involved may be changed according to the orientation of the object. Therefore, the case where the first element is located on the second element includes in the figure or in the actual structure: the case where the first element is located below the second element; and the case where the first element is located above the second element.

[0027] When describing a time relationship, for example, when the time order is described as "after", "subsequently", "next", "before", discontinuous cases may be included, unless "exactly" or "directly" is used.

[0028] It will be understood that although terms such as "first", "second", etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from other elements. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0029] It should be understood that the term "at least one" includes all combinations related to any one item. For example, "at least one of the first element, the second element, and the third element" may include: all combinations of two or more elements selected from the first element, the second element, and the third element; and each of the first element, the second element, and the third element.

[0030] The features of the embodiments of the present invention may be partially or wholly combined or combined with each other, and various interoperations and drives may be performed with each other technically. The embodiments of the present invention may be implemented independently of each other, or may be implemented together in a mutually dependent relationship.

[0031] In the drawings, the same or similar elements are denoted by the same reference numerals, even if they are shown in different figures.

[0032] In the embodiments of the present invention, the source and the drain are distinguished from each other for the sake of explanation. However, the source and the drain may be used interchangeably. Therefore, the source may be the drain, and the drain may be the source. In addition, the source in any one embodiment of the present invention may be the drain in another embodiment of the present invention, and the drain in any one embodiment of the present invention may be the source in another embodiment of the present invention.

[0033] In one or more embodiments of the present invention, for the sake of explanation, the source region and the source are distinguished, and the drain region and the drain are distinguished. However, the embodiments of the present invention are not limited to this structure. For example, the source region may be the source, and the drain region may be the drain. In addition, the source region may be the drain, and the drain region may be the source.

[0034] Figure 1 It is a schematic diagram of a display device according to an embodiment of the present invention.

[0035] As Figure 1 shown, the display device according to an embodiment of the present invention may include a substrate 100 and a plurality of pixels P.

[0036] The plurality of pixels P may be disposed on the substrate 100. Although not specifically illustrated, a plurality of pixels with a quantity of m may be disposed in a first direction of the substrate 100, such as the horizontal direction, and a plurality of pixels with a quantity of n may be disposed in a second direction of the substrate 100, such as the vertical direction. As a result, the display device according to an embodiment of the present invention may include m pixels P in the horizontal direction and n pixels P in the vertical direction, where m and n may be positive numbers, such as positive integers.

[0037] Each of the plurality of pixels P may include a first pixel region SP1, a second pixel region SP2, and a third pixel region SP3 that respectively emit lights of different colors. In this case, the first pixel region SP1, the second pixel region SP2, and the third pixel region SP3 may respectively emit red light, green light, and blue light, but are not limited thereto, and they may also be respectively referred to as a first sub-pixel region, a second sub-pixel region, and a third sub-pixel region. In addition, an additional pixel region that emits white light may be included in each pixel P. In addition, different structures, shapes, sizes, and variations of each pixel P and / or each pixel region may be a part of the present invention.

[0038] Meanwhile, in Figure 1 it, the first pixel region SP1, the second pixel region SP2, and the third pixel region SP3 are arranged in a stripe form, but the present invention is not limited thereto, and the plurality of pixels P may be disposed on the substrate 100 in various pixel arrangement types according to the common general knowledge in the art.

[0039] Figure 2 It is a cross-sectional view of a display device according to an embodiment of the present invention. In this case, Figure 2 corresponds to Figure 1 section I-I'.

[0040] As Figure 2As shown, a display device according to an embodiment of the present invention may include: a substrate 100; a buffer layer 110; an active layer 120; a gate insulating layer 130; a gate 140; an interlayer insulating layer 150; a source 161; a drain 162; a planarization layer 170; a bank 180; a first electrode 200; a second electrode 210; and an organic material layer 300.

[0041] The substrate 100 may be formed of glass or plastic. In particular, the substrate 100 may be formed of a transparent plastic having flexible characteristics, such as polyimide. When polyimide is used as the substrate 100, considering the high-temperature deposition process performed on the substrate 100, a heat-resistant polyimide capable of withstanding high temperatures may be used. Although not shown in the figure, the substrate 100 may include a plurality of substrates such as a first substrate and a second substrate.

[0042] The buffer layer 110 is formed on the substrate 100. The buffer layer 110 may block air and moisture to protect the active layer 120. The buffer layer 110 may be made of an inorganic insulating material such as silicon oxide, silicon nitride, or metal oxide, but is not limited thereto, and it may be made of an organic insulating material.

[0043] The active layer 120 may be formed on the buffer layer 110. The active layer 120 may be formed of a silicon (Si)-based semiconductor material or an oxide-based semiconductor material. A light-blocking layer for blocking external light incident on the active layer 120 may be additionally formed between the buffer layer 110 and the active layer 120.

[0044] The active layer 120 may include: a channel portion 121; a first connection portion 122 provided on one side of the channel portion 121, for example, the left side; and a second connection portion 123 provided on the other side of the channel portion 121, for example, the right side. The first connection portion 122 and the second connection portion 123 have better conductive characteristics than the channel portion 121, and thus can be used as wirings or electrodes. At the same time, when the active layer 120 is formed of an oxide semiconductor, for example, a gate 140 is used as a mask to perform the conductivity process of the first connection portion 122 and the second connection portion 123.

[0045] The gate insulating layer 130 may be formed on the buffer layer 110 and the active layer 120.

[0046] The gate insulating layer 130 may include a silicon nitride layer SiNx or a silicon oxide layer SiOx, but is not limited thereto. The gate insulating layer 130 may have a single-layer structure or a multi-layer structure.

[0047] The gate 140 may be formed on the gate insulating layer 130.

[0048] The gate 140 may include at least one of an aluminum-based metal such as aluminum Al or an aluminum alloy, a silver-based metal such as silver Ag or a silver alloy, a copper-based metal such as copper Cu or a copper alloy, a molybdenum-based metal such as molybdenum Mo or a molybdenum alloy, chromium Cr, tantalum Ta, neodymium Nd, and titanium Ti. The gate 140 may have a multilayer structure including conductor films of at least two different colors.

[0049] The interlayer insulating layer 150 is formed on the gate insulating layer 130 and the gate 140.

[0050] The interlayer insulating layer 150 may be formed of a single layer or multiple layers including an inorganic insulating material and / or an organic insulating material.

[0051] Contact holes may be formed in the interlayer insulating layer 150. In this case, one side of the active layer 120, for example, the first connection portion 122 may be exposed by the contact holes; the other side of the active layer 120, for example, the second connection portion 123 may be exposed by the contact holes.

[0052] The source electrode 161 and the drain electrode 162 may be formed on the interlayer insulating layer 150.

[0053] The source electrode 161 and the drain electrode 162 may include at least one of an aluminum-based metal such as aluminum Al or an aluminum alloy, a silver-based metal such as silver Ag or a silver alloy, a copper-based metal such as copper Cu or a copper alloy, a molybdenum-based metal such as molybdenum Mo or a molybdenum alloy, chromium Cr, tantalum Ta, neodymium Nd, and titanium Ti.

[0054] The source electrode 161 may be electrically connected to one side of the active layer 120, for example, the first connection portion 122, via the contact holes; the drain electrode 162 may be electrically connected to the other side of the active layer 120, for example, the second connection portion 123, via the contact holes.

[0055] The planarization layer 170 may be formed on the source electrode 161 and the drain electrode 162 to planarize the upper surface of the planarization layer 170.

[0056] Contact holes may be provided in the planarization layer 170 to expose a part of the upper surface of the drain electrode 162. At the same time, in some cases, a part of the upper surface of the source electrode 161 may be exposed by the contact holes.

[0057] The planarization layer 170 may be formed of an organic insulating layer material. For example, the planarization layer 170 may be formed of an organic insulating material such as acrylic resin, epoxy resin, phenolic resin, polyamide resin, or polyimide resin.

[0058] The first electrode 200 may be formed on the planarization layer 170. In this case, the first electrode 200 may be patterned in the first pixel region SP1, the second pixel region SP2, and the third pixel region SP3, respectively.

[0059] The first electrode 200 can be electrically connected to the drain 162 via a contact hole formed in the planarization layer 170. The first electrode 200 can be used as an anode.

[0060] The bank 180 can be provided to cover the edge of the first electrode 200 to define a light-emitting region. Thus, the upper surface region of the first electrode 200 that is exposed and not covered by the bank 180 becomes the light-emitting region.

[0061] The bank 180 can be formed of an organic layer such as an acrylic resin, an epoxy resin, a phenolic resin, a polyamide resin, a polyimide resin, or the like.

[0062] The organic material layer 300 can be provided on the first electrode 200. The organic material layer 300 can include: a first organic layer 310; light-emitting layers 320a, 320b, 320c; a second organic layer 330; and third organic layers 340a, 340b. The organic material layer 300 can include the light-emitting layers 320a, 320b, 320c that actually emit light while holes and electrons moving in the first electrode 200 and the second electrode 210 combine to form excitons.

[0063] The first organic layer 310 and the second organic layer 330 can be formed on the upper surfaces of the first electrode 200 and the bank 180, and the light-emitting layers 320a, 320b, 320c can be patterned for each pixel.

[0064] The third organic layers 340a, 340b can include a third organic layer 340a formed in the first pixel region SP1 and a third organic layer 340b formed in the second pixel region SP2. In Figure 2 this case, the third organic layers 340a, 340b are not formed in the third pixel region SP3, but are not limited thereto.

[0065] The third organic layer 340a provided in the first pixel region SP1 and the third organic layer 340b provided in the second pixel region SP2 can be respectively formed on the light-emitting layers 320a and 320b. Meanwhile, the method of forming the third organic layers 340a, 340b is not limited thereto, and the third organic layers 340a, 340b can be continuously provided in the first pixel region SP1 and the second pixel region SP2.

[0066] Each of the third organic layers 340a, 340b can be used to adjust the optical distance in the first pixel region SP1 and the second pixel region SP2, or can adjust the threshold voltage Vth of the first pixel region SP1 and the second pixel region SP2. In this case, the problem of leakage current flowing between the first pixel region SP1 and the second pixel region SP2 can be prevented.

[0067] The light-emitting layers 320a, 320b, and 320c may include a first light-emitting layer 320a patterned in the first pixel region SP1, a second light-emitting layer 320b patterned in the second pixel region SP2, and a third light-emitting layer 320c patterned in the third pixel region SP3. In this case, the first light-emitting layer 320a, the second light-emitting layer 320b, and the third light-emitting layer 320c may include, for example, a red light-emitting layer, a green light-emitting layer, and a blue light-emitting layer, respectively, but are not limited thereto.

[0068] The second electrode 210 may be disposed on the organic material layer 300. The second electrode 210 may be used as a cathode.

[0069] Although not shown, a encapsulation layer for preventing the penetration of moisture or oxygen may be additionally formed on the second electrode 210.

[0070] Figure 3 is a schematic diagram schematically showing a first pixel region, a second pixel region, and a third pixel region of an organic light-emitting diode according to an embodiment of the present invention. Figure 3 The organic light-emitting diode may be a part of a display device of the present invention.

[0071] As Figure 3 shown, an organic light-emitting diode according to an embodiment of the present invention may include a first pixel region SP1, a second pixel region SP2, and a third pixel region SP3.

[0072] The first electrode 200 may be patterned in each of the first pixel region SP1, the second pixel region SP2, and the third pixel region SP3.

[0073] The first electrode 200 may be a reflective electrode. The first electrode 200 may include any one of silver, magnesium, copper, aluminum, platinum, palladium, gold, molybdenum, titanium, and compounds thereof.

[0074] The first organic layer 310 may be disposed on the first electrode 200. The first organic layer 310 may be formed on the entire surfaces of the first pixel region SP1, the second pixel region SP2, and the third pixel region SP3. However, the present invention is not limited thereto. The lower surface of the first organic layer 310 may be in contact with the upper surface of the first electrode 200. However, the present invention is not limited thereto.

[0075] The first organic layer 310 may be at least one of a hole transport layer HTL, a hole injection layer HIL, and an electron blocking layer EBL. According to an embodiment of the present invention, the first organic layer 310 may be, for example, a hole transport layer HTL.

[0076] The first organic layer 310 may be disposed in contact with the upper surface of the first electrode 200 and may move holes migrating from the first electrode 200.

[0077] The third organic layers 340a and 340b are disposed on the first organic layer 310. In this case, the third organic layers 340a and 340b may be disposed in the first pixel region SP1 and the second pixel region SP2, but may not be disposed in the third pixel region SP3.

[0078] The third organic layer 340a disposed in the first pixel region SP1 may be disposed between the first organic layer 310 and the light-emitting layer EML320a.

[0079] The third organic layer 340a can achieve the microcavity characteristics between the first electrode 200 and the second electrode 210 by adjusting the distance between the first electrode 200 and the second electrode 210, that is, the resonance distance. The microcavity characteristics refer to the following characteristics: when the distance between the first electrode 200 and the second electrode 210 becomes an integer multiple of the half-wavelength λ / 2 of the light emitted from the first pixel region SP1, reinforcement interference occurs and the light is amplified, and by repeating the reflection and re-reflection processes between the first electrode 200 and the second electrode 210, the degree of light amplification continuously increases, thereby improving the external extraction efficiency of the light.

[0080] In addition, the third organic layer 340a can be adjusted to the threshold voltage Vth required for the light-emitting layer 320a to emit light, so as to prevent the current generated in the first pixel region SP1 from leaking to other pixel regions.

[0081] The third organic layer 340b disposed in the second pixel region SP2 may be disposed between the first organic layer 310 and the light-emitting layer EML320b.

[0082] In this case, the third organic layer 340b disposed in the second pixel region SP2 can perform the same functions as the third organic layer 340a disposed in the first pixel region SP1, so its repeated description will be omitted.

[0083] The light-emitting layer EML 320a disposed in the first pixel region SP1 may be disposed on the third organic layer 340a. In this case, the light-emitting layer EML 320a disposed in the first pixel region SP1 may emit red light, for example. The light-emitting layer EML 320b disposed in the second pixel region SP2 may be disposed on the third organic layer 340b, and in this case, the light-emitting layer 320b disposed in the second pixel region SP2 may emit green light, for example. In addition, the light-emitting layer EML320c disposed in the third pixel region SP3 may be directly disposed on the first organic layer 310, but is not limited thereto. In this case, the light-emitting layer EML 320c disposed in the third pixel region SP3 may emit blue light, for example.

[0084] The second organic layer 330 may be provided as a common layer in all of the first pixel region SP1, the second pixel region SP2, and the third pixel region SP3. The second organic layer 330 may be provided on the light-emitting layers 320a, 320b, and 320c. The third organic layer 340 may be at least one of an electron transport layer ETL, an electron injection layer EIL, and a hole blocking layer HBL. The third organic layer 340 may be, for example, an electron transport layer ETL.

[0085] The second electrode 210 may be provided as a common layer in all of the first pixel region SP1, the second pixel region SP2, and the third pixel region SP3. Specifically, the second electrode 210 may be provided on the second organic layer 330. Accordingly, the top surface of the second organic layer 330 may be in contact with the bottom surface of the second electrode 210. However, the present invention is not limited thereto.

[0086] According to an embodiment of the present invention, the refractive index of the first organic layer 310 may be greater than the refractive index of the second organic layer 330, and other layers provided between the first organic layer 310 and the second organic layer 330 may have a gradually decreasing refractive index from the first electrode 200 toward the second electrode 210. In this case, since the light emitted from the light-emitting layers 320a, 320b, 320c is reflected from the first electrode 200 and moves to the upper surface of the second electrode 210, the refraction angle increases, and the brightness at the side surface of the organic light-emitting diode according to the embodiment of the present invention may be improved. Meanwhile, a more detailed description thereof will be made with reference to Figures 4 to 8 this.

[0087] Figure 4 is a cross-sectional view schematically illustrating a part of an organic light-emitting diode according to an embodiment of the present invention.

[0088] will be described in detail with reference to Figure 4 the principle of improving the viewing angle on the side surface in the first pixel region (see SP1 in Figure 3 ) or the second pixel region (see SP2 in Figure 3 ) of the organic light-emitting diode according to an embodiment of the present invention. Meanwhile, Figure 4 the embodiment of Figure 3 corresponds to a view schematically illustrating either the first pixel region SP1 or the second pixel region PS2 of

[0089] As Figure 4As shown, in the organic light-emitting diode according to an embodiment of the present invention, a first organic layer 310 as a first layer, a third organic layer 340 as a third layer, a light-emitting layer EML 320, and a second organic layer 330 are sequentially formed from the bottom in the figure. According to an embodiment of the present invention, the first organic layer 310 as the first layer may have a first refractive index n1, the light-emitting layer EML 320 may have a second refractive index n2, the second organic layer 330 as the second layer may have a third refractive index n3, and the third organic layer 340 may have a fourth refractive index n4.

[0090] According to an embodiment of the present invention, the first refractive index n1 of the first organic layer 310 may be greater than the third refractive index n3 of the second organic layer 330, and the first refractive index n1 of the first organic layer 310 may be equal to the fourth refractive index n4 of the third organic layer 340 and the second refractive index n2 of the light-emitting layer 320. By forming in this way, the viewing angle in the side surface of the light emitted from the first pixel region (see Figure 3 SP1) or the second pixel region (see Figure 3 SP2) can be improved.

[0091] More specifically, the light emitted from the light-emitting layer 320 may sequentially pass through the light-emitting layer 320, the third organic layer 340, and the first organic layer 310, may be reflected by a first electrode 200 (see Figure 3 ) provided on the lower surface of the first organic layer 310, may sequentially pass through the first organic layer 310, the third organic layer 340, the light-emitting layer 320, and the second organic layer 330, and may be emitted to the upper surface of the second organic layer 330.

[0092] Since the first refractive index n1, the second refractive index n2, and the fourth refractive index n4 are the same, the light sequentially passing through the first organic layer 310, the third organic layer 340, and the light-emitting layer 320 is not refracted. The light may travel at a first angle a1 toward the interface between the light-emitting layer 320 and the second organic layer 330, and since the second refractive index n2 of the light-emitting layer 320 is greater than the third refractive index n3 of the second organic layer 330, the light may be refracted at a second angle b1 and emitted from the interface between the light-emitting layer 320 and the second organic layer 330. In this case, the second angle b1 may be formed to be greater than the first angle a1. The first angle a1 may be defined as the angle formed by the light traveling toward the interface between the light-emitting layer 320 and the second organic layer 330 based on the normal line of the interface between the light-emitting layer 320 and the second organic layer 330; the second angle b1 may be defined as the angle formed by the light emitted from the interface between the light-emitting layer 320 and the second organic layer 330 based on the normal line of the interface between the light-emitting layer 320 and the second organic layer 330.

[0093] Meanwhile, the first angle a1 and the second angle b1 can be adjusted according to the knowledge in the art to a level such that total internal reflection of light does not occur at each interface. Thus, light is not trapped inside the light-emitting layer 320 or the second organic layer 330.

[0094] According to an embodiment of the present invention, since the light traveling in a direction away from the interface between the light-emitting layer 320 and the second organic layer 330 is emitted at a second angle b1 greater than the first angle a1, the brightness on the side surface of the organic light-emitting diode according to the embodiment of the present invention can be increased, thereby improving the brightness viewing angle of the display device.

[0095] Table 1 shows the brightness at a 45-degree angle with respect to the difference between the first refractive index n1 of the first organic layer 310 and the third refractive index n3 of the second organic layer 330 in the case where the organic light-emitting diode according to the embodiment of the present invention is Figure 3 the first pixel region SP1. In this case, based on the brightness of 100% measured at a 45-degree angle in Comparative Example 1, the relative brightness measured at a 45-degree angle in Examples 1a to 1c is shown.

[0096] Table 1:

[0097]

[0098] As shown in Table 1, in Examples 1a, 1b, and 1c where the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, higher brightness can be obtained compared to Comparative Example 1 where the first refractive index n1 of the first organic layer 310 is less than the third refractive index n3 of the second organic layer 330. As a result, as shown in Examples 1a to 1c and Comparative Example 1, since the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, the brightness on the side surface of the organic light-emitting diode according to the embodiment of the present invention can be improved, thereby improving the brightness viewing angle of the organic light-emitting diode.

[0099] Table 2 shows the brightness at a 45-degree angle with respect to the difference between the first refractive index n1 of the first organic layer 310 and the third refractive index n3 of the second organic layer 330 in the case where the organic light-emitting diode according to the embodiment of the present invention is Figure 3 the second pixel region SP2. In this case, based on the brightness of 100% measured at a 45-degree angle in Comparative Example 2, the relative brightness measured at a 45-degree angle in Examples 2a to 2c is shown.

[0100] Table 2:

[0101]

[0102] As shown in Table 2, in Examples 2a, 2b, and 2c where the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, higher luminance can be obtained compared to Comparative Example 2 where the first refractive index n1 of the first organic layer 310 is less than the third refractive index n3 of the second organic layer 330. As a result, as shown in Examples 2a to 2c and Comparative Example 2, since the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, the luminance on the side surface of the organic light-emitting diode according to an embodiment of the present invention can be improved, thereby improving the luminance viewing angle of the organic light-emitting diode.

[0103] Figure 5 is a schematic cross-sectional view illustrating a part of an organic light-emitting diode according to another embodiment of the present invention. Meanwhile, except for the relationship between the refractive index of the light-emitting layer and the refractive index of the third organic layer, Figure 5 the embodiment of Figure 4 is the same as the embodiment of

[0104] According to another embodiment of the present invention, the first refractive index n1 of the first organic layer 310 may be greater than the third refractive index n3 of the second organic layer 330, the fourth refractive index n4 of the third organic layer 340 may be greater than the second refractive index n2 of the light-emitting layer 320, the second refractive index n2 of the light-emitting layer 320 may be greater than the third refractive index n3 of the second organic layer 330, and the first refractive index n1 of the first organic layer 310 and the fourth refractive index n4 of the third organic layer 340 may be the same. By forming in this way, the viewing angle in the side surface of the light emitted from the first pixel region (see Figure 3 SP1 of Figure 3 or the second pixel region (see

[0105] Since the first refractive index n1 and the fourth refractive index n4 are the same, the light passing through the first organic layer 310 and the third organic layer 340 in sequence is not refracted. The light may travel at a first angle a1 toward the interface between the third organic layer 340 and the light-emitting layer 320, and since the fourth refractive index n4 of the third organic layer 340 is greater than the second refractive index n2 of the light-emitting layer 320, the light can be refracted at a second angle b1 and emitted from the interface between the third organic layer 340 and the light-emitting layer 320. In this case, the second angle b1 may be formed to be greater than the first angle a1. The first angle a1 may be defined as the angle formed by the light traveling toward the interface between the light-emitting layer 320 and the third organic layer 340 based on the normal line of the interface between the light-emitting layer 320 and the third organic layer 340; the second angle b1 may be defined as the angle formed by the light emitted from the interface between the light-emitting layer 320 and the third organic layer 340 based on the normal line of the interface between the light-emitting layer 320 and the third organic layer 340.

[0106] In addition, since light travels toward the interface between the light-emitting layer 320 and the second organic layer 330 at the second angle b1, and the second refractive index n2 of the light-emitting layer 320 is greater than the third refractive index n3 of the second organic layer 330, the light is refracted at the third angle c1 and emitted from the interface between the light-emitting layer 320 and the second organic layer 330. In this case, the third angle c1 can be formed to be greater than the second angle b1. Therefore, the third angle c1 is formed to be greater than the first angle a1. The third angle c1 can be defined as the angle formed by the light emitted from the interface between the light-emitting layer 320 and the second organic layer 330 based on the normal line of the interface between the light-emitting layer 320 and the second organic layer 330.

[0107] Meanwhile, the first angle a1, the second angle b1, and the third angle c1 can be adjusted according to the knowledge in the art to a level such that total internal reflection of light does not occur at each interface. Therefore, light is not trapped inside the light-emitting layer 320, the second organic layer 330, or the third organic layer 340.

[0108] According to another embodiment of the present invention, since the light traveling in the direction away from the interface between the light-emitting layer 320 and the second organic layer 330 is emitted at the third angle c1 greater than the first angle a1, the brightness on the side surface of the organic light-emitting diode according to another embodiment of the present invention can be increased, thereby improving the brightness viewing angle of the display device.

[0109] Table 3 shows the brightness at a 45-degree angle regarding the difference between the first refractive index n1 of the first organic layer 310 and the third refractive index n3 of the second organic layer 330 in the case where the organic light-emitting diode according to another embodiment of the present invention is Figure 3 the first pixel region SP1. In this case, based on the brightness of 100% measured at a 45-degree angle in Comparative Example 1, the relative brightness measured at a 45-degree angle in Examples 3a to 3c is shown.

[0110] Table 3:

[0111]

[0112] As shown in Table 3, in Examples 3a, 3b, and 3c where the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, higher luminance can be obtained compared to Comparative Example 1 where the first refractive index n1 of the first organic layer 310 is less than the third refractive index n3 of the second organic layer 330. As a result of examining Examples 3a to 3c and Comparative Example 1, since the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, the luminance at the side surface of the organic light-emitting diode according to another embodiment of the present invention can be improved, thereby improving the luminance viewing angle of the organic light-emitting diode. In addition, referring to Table 1 and Table 3, it can be seen that the luminance is relatively higher when the first refractive index n1 of the first organic layer 310 and the fourth refractive index n4 of the third organic layer 340 are the same and the second refractive index n2 of the light-emitting layer 320 is less than the first refractive index n1 (or the fourth refractive index n4) (Examples 3a to 3c) than when the first refractive index n1 of the first organic layer 310, the fourth refractive index n4 of the third organic layer 340, and the second refractive index n2 of the light-emitting layer 320 are all the same (Examples 1a to 1c).

[0113] Table 4 shows the luminance at a 45-degree angle with respect to the difference between the first refractive index n1 of the first organic layer 310 and the third refractive index n3 of the second organic layer 330 in the case where the organic light-emitting diode according to another embodiment of the present invention is Figure 3 the second pixel region SP2. In this case, based on 100% of the luminance measured at a 45-degree angle in Comparative Example 2, the relative luminance measured at a 45-degree angle in Examples 4a to 4c is shown.

[0114] Table 4:

[0115]

[0116] As shown in Table 4, in Examples 4a, 4b, and 4c where the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, higher luminance can be obtained compared to Comparative Example 2 where the first refractive index n1 of the first organic layer 310 is less than the third refractive index n3 of the second organic layer 330. As a result of examining Examples 4a to 4c and Comparative Example 2, since the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, the luminance on the side surface of the organic light-emitting diode according to another embodiment of the present invention can be improved, thereby improving the luminance viewing angle of the organic light-emitting diode. In addition, referring to Tables 2 and 4, it can be seen that the luminance is relatively higher when the first refractive index n1 of the first organic layer 310 and the fourth refractive index n4 of the third organic layer 340 are the same and the second refractive index n2 of the light-emitting layer 320 is less than the first refractive index n1 or the fourth refractive index n4 (Examples 4a to 4c) than when the first refractive index n1 of the first organic layer 310, the fourth refractive index n4 of the third organic layer 340, and the second refractive index n2 of the light-emitting layer 320 are all the same (Examples 2a to 2c).

[0117] Figure 6 is a cross-sectional view schematically illustrating a part of an organic light-emitting diode according to another embodiment of the present invention. Meanwhile, except for the relationship between the refractive index of the first organic layer and the refractive index of the third organic layer and the relationship between the refractive index of the light-emitting layer and the refractive index of the third organic layer, Figure 6 the embodiment of Figure 4 is the same as the embodiment of

[0118] According to another embodiment of the present invention, the first refractive index n1 of the first organic layer 310 may be greater than the third refractive index n3 of the second organic layer 330, the fourth refractive index n4 of the third organic layer 340 may be greater than the second refractive index n2 of the light-emitting layer 320, the second refractive index n2 of the light-emitting layer 320 may be greater than the third refractive index n3 of the second organic layer 330, and the first refractive index n1 of the first organic layer 310 may be greater than the fourth refractive index n4 of the third organic layer 340. By forming in this way, the viewing angle in the side surface of the light emitted from the first pixel region (see SP1 of Figure 3 ) or the second pixel region (see SP2 of Figure 3 ) can be improved.

[0119] Since the first refractive index n1, the fourth refractive index n4, the second refractive index n2, and the third refractive index n3 are set to decrease in sequence, light can be refracted each time it passes through the interface of each layer. Specifically, light can travel toward the interface between the first organic layer 310 and the third organic layer 340 at a first angle a1, and since the first refractive index n1 of the first organic layer 310 is greater than the fourth refractive index n4 of the third organic layer 340, the light can be refracted at a second angle b1 and emitted from the interface between the first organic layer 310 and the third organic layer 340. In this case, the second angle b1 can be formed to be greater than the first angle a1. The first angle a1 can be defined as the angle formed by light traveling toward the interface between the first organic layer 310 and the third organic layer 340 based on the normal line of the interface between the first organic layer 310 and the third organic layer 340; the second angle b1 can be defined as the angle formed by light emitted from the interface between the first organic layer 310 and the third organic layer 340 based on the normal line of the interface between the first organic layer 310 and the third organic layer 340.

[0120] Next, the light can travel toward the interface between the third organic layer 340 and the light-emitting layer 320 at the second angle b1, and since the fourth refractive index n4 of the third organic layer 340 is greater than the second refractive index n2 of the light-emitting layer 320, the light can be refracted at a third angle c1 and emitted from the interface between the third organic layer 340 and the light-emitting layer 320. In this case, the third angle c1 can be formed to be greater than the second angle b1. The third angle c1 can be defined as the angle formed by light emitted from the interface between the light-emitting layer 320 and the third organic layer 340 based on the normal line of the interface between the light-emitting layer 320 and the third organic layer 340.

[0121] In addition, since the light travels toward the interface between the light-emitting layer 320 and the second organic layer 330 at the third angle c1, and the second refractive index n2 of the light-emitting layer 320 is greater than the third refractive index n3 of the second organic layer 330, the light can be refracted at a fourth angle d1 and emitted from the interface between the light-emitting layer 320 and the second organic layer 330. In this case, the fourth angle d1 can be formed to be greater than the third angle c1. Thus, the fourth angle d1 can be formed to be greater than the first angle a1. The fourth angle d1 can be defined as the angle formed by light emitted from the interface between the light-emitting layer 320 and the second organic layer 330 based on the normal line of the interface between the light-emitting layer 320 and the second organic layer 330.

[0122] Meanwhile, the first angle a1, the second angle b1, the third angle c1, and the fourth angle d1 can be adjusted to a level such that total internal reflection of light does not occur at each interface according to the knowledge in the art. Therefore, light will not be trapped inside the first organic layer 310, the light-emitting layer 320, the second organic layer 330, or the third organic layer 340.

[0123] According to another embodiment of the present invention, since the light traveling in the direction away from the interface between the light-emitting layer 320 and the second organic layer 330 is emitted at a fourth angle d1 greater than the first angle a1, the brightness on the side surface of the organic light-emitting diode according to another embodiment of the present invention can be increased, thereby improving the brightness viewing angle of the display device.

[0124] Table 5 shows the brightness at a 45-degree angle with respect to the difference between the first refractive index n1 of the first organic layer 310 and the third refractive index n3 of the second organic layer 330 in the case where the organic light-emitting diode according to another embodiment of the present invention is Figure 3 the first pixel region SP1. In this case, based on the brightness of 100% measured at a 45-degree angle in Comparative Example 1, the relative brightness measured at a 45-degree angle in Examples 5a to 5c is shown.

[0125] Table 5:

[0126]

[0127] As shown in Table 5, in Examples 5a, 5b, and 5c where the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, higher brightness can be obtained compared to Comparative Example 1 where the first refractive index n1 of the first organic layer 310 is less than the third refractive index n3 of the second organic layer 330. As a result of examining Examples 5a to 5c and Comparative Example 1, since the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, the brightness at the side surface of the organic light-emitting diode according to another embodiment of the present invention can be improved, thereby improving the brightness viewing angle of the organic light-emitting diode. In addition, referring to Tables 1, 3, and 5, it can be seen that the brightness when the first refractive index n1, the fourth refractive index n4, the second refractive index n2, and the third refractive index n3 decrease in sequence (Examples 5a to 5c) is relatively higher than the brightness when the first refractive index n1 of the first organic layer 310, the fourth refractive index n4 of the third organic layer 340, and the second refractive index n2 of the light-emitting layer 320 are all the same (Examples 1a to 1c), and is relatively higher than the brightness when the first refractive index n1 of the first organic layer 310 is the same as the fourth refractive index n4 of the third organic layer 340 and the second refractive index n2 of the light-emitting layer 320 is less than the first refractive index n1 (or the fourth refractive index n4) (Examples 3a to 3c).

[0128] Table 6 shows the case where the organic light-emitting diode according to another embodiment of the present invention is Figure 3In the case of the second pixel region SP2, the luminance at a 45-degree angle with respect to the difference between the first refractive index n1 of the first organic layer 310 and the third refractive index n3 of the second organic layer 330. In this case, based on the luminance of 100% measured at a 45-degree angle in Comparative Example 2, the relative luminance measured at a 45-degree angle in Examples 6a to 6c is shown.

[0129] Table 6:

[0130]

[0131] As shown in Table 6, in Examples 6a, 6b, and 6c where the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, higher luminance can be obtained compared to Comparative Example 2 where the first refractive index n1 of the first organic layer 310 is less than the third refractive index n3 of the second organic layer 330. As a result of examining Examples 6a to 6c and Comparative Example 2, since the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, the luminance on the side surface of the organic light-emitting diode according to another embodiment of the present invention can be improved, thereby improving the luminance viewing angle of the organic light-emitting diode. In addition, referring to Tables 2, 4, and 6, it can be seen that the luminance when the first refractive index n1, the fourth refractive index n4, the second refractive index n2, and the third refractive index n3 decrease in order (Examples 6a to 6c) is relatively higher than the luminance when the first refractive index n1 of the first organic layer 310, the fourth refractive index n4 of the third organic layer 340, and the second refractive index n2 of the light-emitting layer 320 are all the same (Examples 2a to 2c), and is relatively higher than the luminance when the first refractive index n1 of the first organic layer 310 is the same as the fourth refractive index n4 of the third organic layer 340, and the second refractive index n2 of the light-emitting layer 320 is less than the first refractive index n1 (or the fourth refractive index n4) (Examples 4a to 4c).

[0132] Figure 7 is a schematic cross-sectional view illustrating a part of an organic light-emitting diode according to another embodiment of the present invention.

[0133] will be described in detail with reference to Figure 7 the principle of improving the viewing angle on the side surface in the third pixel region (see SP3 in Figure 3 ) of the organic light-emitting diode according to an embodiment of the present invention.

[0134] As Figure 7As shown, in the organic light-emitting diode according to an embodiment of the present invention, starting from the bottom in the figure, a first organic layer 310 as a first layer, a light-emitting layer EML 320, and a second organic layer 330 as a second layer are sequentially formed. According to an embodiment of the present invention, the first organic layer 310 as the first layer may have a first refractive index n1, the light-emitting layer EML 320 may have a second refractive index n2, and the second organic layer 330 as the second layer may have a third refractive index n3.

[0135] According to another embodiment of the present invention, the first refractive index n1 of the first organic layer 310 may be greater than the third refractive index n3 of the second organic layer 330, and the first refractive index n1 of the first organic layer 310 and the second refractive index n2 of the light-emitting layer 320 may be the same. By forming in this way, the viewing angle in the side surface of the light emitted from the third pixel region (see Figure 3 SP3) can be improved.

[0136] Since the first refractive index n1 and the second refractive index n2 are the same, the light passing through the first organic layer 310 and the light-emitting layer 320 in sequence is not refracted and passes through. In this case, the light may travel at a first angle a1' toward the interface between the light-emitting layer 320 and the second organic layer 330, and since the second refractive index n2 of the light-emitting layer 320 is greater than the third refractive index n3 of the second organic layer 330, the light can be refracted at a second angle b1' and emitted from the interface between the light-emitting layer 320 and the second organic layer 330. In this case, the second angle b1' may be formed to be greater than the first angle a1'. The first angle a1' may be defined as the angle formed by the normal line of the interface between the light-emitting layer 320 and the second organic layer 330 and the light traveling toward the interface between the light-emitting layer 320 and the second organic layer 330; the second angle b1' may be defined as the angle formed by the normal line of the interface between the light-emitting layer 320 and the second organic layer 330 and the light traveling away from the interface between the light-emitting layer 320 and the second organic layer 330.

[0137] Meanwhile, the first angle a1' and the second angle b1' can be adjusted to a level such that total internal reflection of light does not occur at each interface according to the knowledge in the art. Therefore, the light is not trapped inside the light-emitting layer 320 or the second organic layer 330.

[0138] According to another embodiment of the present invention, since the light traveling in the direction away from the interface between the light-emitting layer 320 and the second organic layer 330 is emitted at a second angle b1' greater than the first angle a1', the brightness on the side surface of the organic light-emitting diode according to another embodiment of the present invention can be increased, thereby improving the viewing angle on the side surface of the display device.

[0139] Table 7 shows that in the organic light-emitting diode according to another embodiment of the present invention Figure 3In the case of the third pixel region SP3, regarding the difference between the first refractive index n1 of the first organic layer 310 and the third refractive index n3 of the second organic layer 330, the luminance at a 45-degree angle. In this case, based on 100% of the luminance measured at a 45-degree angle in Comparative Example 3, the relative luminance measured at a 45-degree angle in Examples 7a to 7c is shown.

[0140] Table 7:

[0141]

[0142] As shown in Table 7, in Examples 7a, 7b, and 7c where the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, higher luminance can be obtained compared to Comparative Example 3 where the first refractive index n1 of the first organic layer 310 is less than the third refractive index n3 of the second organic layer 330.

[0143] As a result of examining Examples 7a to 7c and Comparative Example 3, since the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, the luminance on the side surface of the organic light-emitting diode according to another embodiment of the present invention can be improved, thereby improving the luminance viewing angle of the organic light-emitting diode.

[0144] Figure 8 is a schematic perspective view illustrating a part of an organic light-emitting diode according to another embodiment of the present invention. At the same time, except for the relationship between the refractive index of the first organic layer and the refractive index of the light-emitting layer, Figure 8 The embodiment of Figure 7 is the same as the embodiment of

[0145] According to another embodiment of the present invention, the first refractive index n1 of the first organic layer 310 may be greater than the third refractive index n3 of the second organic layer 330, the first refractive index n1 of the first organic layer 310 may be greater than the second refractive index n2 of the light-emitting layer 320, and the second refractive index n2 of the light-emitting layer 320 may be greater than the third refractive index n3 of the second organic layer 330. By forming in this way, the viewing angle in the side surface of the light emitted from the third pixel region (see Figure 3 SP3) can be improved.

[0146] Since the first refractive index n1 of the first organic layer 310, the second refractive index n2 of the light-emitting layer 320, and the third refractive index n3 of the second organic layer 330 are set to decrease in sequence, light can be refracted each time it passes through the interface of each layer. Specifically, light can travel toward the interface between the first organic layer 310 and the light-emitting layer 320 at a first angle a1', and since the first refractive index n1 of the first organic layer 310 is greater than the second refractive index n2 of the light-emitting layer 320, the light can be refracted at a second angle b1' and emitted from the interface between the first organic layer 310 and the light-emitting layer 320. In this case, the second angle b1' can be formed to be greater than the first angle a1'. The first angle a1' can be defined as the angle formed by the normal line of the interface between the first organic layer 310 and the light-emitting layer 320 and the light traveling toward the interface between the first organic layer 310 and the light-emitting layer 320; the second angle b1' can be defined as the angle formed by the normal line of the interface between the first organic layer 310 and the light-emitting layer 320 and the light traveling away from the interface between the first organic layer 310 and the light-emitting layer 320.

[0147] Next, the light can travel toward the interface between the light-emitting layer 320 and the second organic layer 330 at the second angle b1', and since the second refractive index n2 of the light-emitting layer 320 is greater than the third refractive index n3 of the second organic layer 330, the light can be refracted at a third angle c1' and emitted from the interface between the light-emitting layer 320 and the second organic layer 330. In this case, the third angle c1' can be formed to be greater than the second angle b1'. Therefore, the third angle c1' can be formed to be greater than the first angle a1'. The third angle c1' can be defined as the angle formed by the normal line of the interface between the light-emitting layer 320 and the second organic layer 330 and the light emitted from the interface between the light-emitting layer 320 and the second organic layer 330.

[0148] Meanwhile, the first angle a1', the second angle b1', and the third angle c1' can be adjusted to a level such that total internal reflection of light does not occur at each interface according to the knowledge in the art. Therefore, light is not trapped inside the first organic layer 310, the light-emitting layer 320, or the second organic layer 330.

[0149] According to another embodiment of the present invention, since the light traveling in the direction away from the interface between the light-emitting layer 320 and the second organic layer 330 is emitted at a third angle c1' greater than the first angle a1', the brightness on the side surface of the organic light-emitting diode according to another embodiment of the present invention increases, thereby improving the viewing angle on the side surface of the display device.

[0150] Table 8 shows that the organic light-emitting diode according to another embodiment of the present invention is Figure 3In the case of the third pixel region SP3, regarding the difference between the first refractive index n1 of the first organic layer 310 and the third refractive index n3 of the second organic layer 330, the luminance at a 45-degree angle. In this case, based on the 100% luminance measured at a 45-degree angle in Comparative Example 3, the relative luminance measured at a 45-degree angle in Examples 8a to 8c is shown.

[0151] Table 8:

[0152]

[0153] As shown in Table 8, in Examples 8a, 8b, and 8c where the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, higher luminance can be obtained compared to Comparative Example 3 where the first refractive index n1 of the first organic layer 310 is less than the third refractive index n3 of the second organic layer 330. As a result of examining Examples 8a to 8c and Comparative Example 3, since the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, the luminance on the side surface of the organic light-emitting diode according to another embodiment of the present invention can be improved, thereby improving the luminance viewing angle of the organic light-emitting diode. In addition, referring to Table 7 and Table 8, it can be seen that the luminance when the second refractive index n2 of the light-emitting layer 320 is less than the first refractive index n1 of the first organic layer 310 (Examples 8a to 8c) is relatively higher than the luminance when the first refractive index n1 of the first organic layer 310 is the same as the second refractive index n2 of the light-emitting layer 320 (Examples 7a to 7c).

[0154] Figure 9 is a graph showing the luminance based on the viewing angle of an organic light-emitting diode according to an embodiment of the present invention. Specifically, Figure 9 is a graph showing how the luminance value changes relatively based on the viewing angle of an organic light-emitting device according to an embodiment of the present invention when the luminance at the current side is 100%. In this case, the comparative example is the case where the first refractive index of the first organic layer is less than the second refractive index of the second organic layer, and the example is the case where the first refractive index of the first organic layer is greater than the second refractive index of the second organic layer.

[0155] As Figure 9 shown, the relative luminance intensity based on the viewing angle of the organic light-emitting device according to the embodiment is greater than the relative luminance intensity based on the viewing angle of the organic light-emitting device according to the comparative example. Specifically, referring to the luminance at a 45-degree angle, it can be seen that the comparative example has a luminance slightly lower than 40%, while the example has a luminance higher than 40%.

[0156] Therefore, according to an embodiment of the present invention, when the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, it can be confirmed that the brightness on the side surface can be increased.

[0157] Meanwhile, Table 9 is a table showing the relative brightness at a 45-degree angle measured based on the difference Δn between the first refractive index n1 of the first organic layer 310 and the third refractive index n3 of the second organic layer 330 in an organic light-emitting diode according to an embodiment of the present invention. In this case, in Table 9 below, the brightness of Examples 9b to 9g refers to the relative brightness when the brightness measured at a 45-degree angle in Example 9a is 100%.

[0158] Table 9:

[0159]

[0160] As shown in Table 9, it can be seen that the brightness on the side surface is improved when the first refractive index n1 is formed to be greater than the third refractive index n3. Preferably, when the difference Δn between the first refractive index n1 and the third refractive index n3 is 0.15 to 0.5 (0.15 to 0.5 means greater than or equal to 0.15 and less than or equal to 0.5), the brightness (%) at a 45-degree angle can be further increased, thereby further improving the viewing angle on the side surface. Meanwhile, when the difference Δn between the first refractive index n1 and the third refractive index n3 exceeds 0.5, since the light trapped inside the organic light-emitting device increases due to total internal reflection occurring in the first organic layer 310 or the second organic layer 330, the brightness on the side surface does not increase further but rather decreases. In addition, referring to Figure 9 and Table 9, according to an embodiment of the present invention, it can be seen that when the first refractive index n1 of the first organic layer 310 is greater than the third refractive index n3 of the second organic layer 330, the brightness on the side surface can be further improved. Preferably, when the difference Δn between the first refractive index n1 of the first organic layer 310 and the third refractive index n3 of the second organic layer 330 is 0.15 to 0.5, the brightness on the side surface is further improved.

[0161] Table 10 shows the brightness measured at a 45-degree angle after differently setting the ratio of the difference between the first refractive index n1 of the first organic layer 310 and the second refractive index n2 of the light-emitting layer 320 to the difference between the second refractive index n2 of the light-emitting layer 320 and the third refractive index n3 of the second organic layer 330. In this case, in Table 10, the brightness of Examples 10a to 10e (excluding 10c) represents the relative brightness when the brightness measured at a 45-degree angle in Example 10c is 100%.

[0162] Table 10:

[0163]

[0164] As shown in Table 10, when the ratio of the difference between the first refractive index n1 of the first organic layer 310 and the second refractive index n2 of the light-emitting layer 320 to the difference between the second refractive index n2 of the light-emitting layer 320 and the third refractive index n3 of the second organic layer 330 is from 4:21 to 16:9, a luminance of 94% or higher can be obtained, and thus the viewing angle on the side surface can be further improved. In addition, as can be seen from Table 10, when Example 10a is compared with Example 10e, it can be seen that the luminance at the side surface (45 degrees) in the case of Example 10a is 94%, while the luminance at the side surface in the case of Example 10e is 90%. In addition, when Example 10b is compared with Example 10d, it can be seen that the luminance at the side surface in the case of Example 10b is 97%, while the luminance in the case of Example 10d is 94%. As a result, when the difference between the first refractive index n1 of the first organic layer 310 and the second refractive index n2 of the light-emitting layer 320 is smaller than the difference between the second refractive index n2 of the light-emitting layer 320 and the third refractive index n3 of the second organic layer 330, an organic light-emitting device with a further improved viewing angle can be realized.

[0165] Table 11 below shows the luminance measured at a 45-degree angle when the first refractive index n1 of the first organic layer 310 is greater than or equal to the second refractive index n2 of the light-emitting layer 320 (Example 11) and the luminance measured at a 45-degree angle when the first refractive index n1 of the first organic layer 310 is smaller than the second refractive index n2 of the light-emitting layer 320 (Comparative Examples 11a to 11c).

[0166] Table 11:

[0167]

[0168] As shown in Table 11, it can be seen that the luminance when the first refractive index n1 of the first organic layer 310 is smaller than the second refractive index n2 of the light-emitting layer 320 (Comparative Examples 11a to 11c) is lower than the luminance when the first refractive index n1 of the first organic layer 310 is greater than or equal to the second refractive index n2 of the light-emitting layer 320 (Example 11). As a result, according to an embodiment of the present invention, when the first refractive index n1 is greater than or equal to the second refractive index n2 of the light-emitting layer 320, high luminance in the side surface can be obtained.

[0169] Therefore, the present invention can have the following advantages.

[0170] According to an embodiment of the present invention, since the first refractive index of the first organic layer provided on the first electrode is greater than the third refractive index of the second organic layer provided under the second electrode, an organic light-emitting diode having high luminance on the side surface can be realized.

[0171] According to an embodiment of the present invention, since a first refractive index of a first organic layer provided on a first electrode is greater than a second refractive index of a light-emitting layer provided on the first organic layer, and the second refractive index of the light-emitting layer is greater than a third refractive index of a second organic layer provided on the light-emitting layer, an organic light-emitting diode having high luminance on a side surface can be realized.

[0172] According to an embodiment of the present invention, since a first refractive index of a first organic layer provided on a first electrode is greater than a fourth refractive index of a third organic layer provided on the first organic layer, the fourth refractive index of the third organic layer is greater than the second refractive index of the light-emitting layer, and the second refractive index of the light-emitting layer is greater than a third refractive index of a second organic layer provided on the light-emitting layer, an organic light-emitting diode having high luminance on a side surface can be realized.

[0173] According to an embodiment of the present invention, by realizing an organic light-emitting diode having high luminance on a side surface, an organic light-emitting diode and a display device having an improved side viewing angle can be realized.

[0174] It will be apparent to those of ordinary skill in the art that various alternatives, modifications, and variations can be made within the scope of the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning, scope, and equivalent concepts of the claims should be construed as being included within the scope of the present invention.

Claims

1. An organic light emitting diode, comprising: a first electrode; a first organic layer disposed on the first electrode and having a first refractive index; a light-emitting layer disposed on the first organic layer and having a second refractive index; a second organic layer disposed on the light-emitting layer and having a third refractive index; as well as a second electrode disposed on the second organic layer, wherein the first refractive index is equal to or greater than the second refractive index, The second refractive index is greater than the third refractive index.

2. The organic light emitting diode according to claim 1, The first refractive index is the same as the second refractive index.

3. The organic light emitting diode according to claim 2, further comprising: a third organic layer disposed between the first organic layer and the light-emitting layer, The fourth refractive index of the third organic layer is the same as the first refractive index.

4. The organic light emitting diode according to claim 1, The first refractive index is greater than the second refractive index.

5. The organic light emitting diode according to claim 4, further comprising: a third organic layer disposed between the first organic layer and the light-emitting layer, The fourth refractive index of the third organic layer is the same as the first refractive index.

6. The organic light emitting diode according to claim 4, further comprising: a third organic layer disposed between the first organic layer and the light-emitting layer, The fourth refractive index of the third organic layer is smaller than the first refractive index and larger than the second refractive index.

7. The organic light emitting diode according to claim 1, The difference between the first refractive index and the third refractive index is greater than or equal to 0.15 and less than or equal to 0.

5.

8. The organic light emitting diode according to claim 7, The difference between the first refractive index and the second refractive index is smaller than the difference between the second refractive index and the third refractive index.

9. The organic light emitting diode according to claim 7, Wherein a ratio of a difference between the first refractive index and the second refractive index to a difference between the second refractive index and the third refractive index is 4:21 to 16:

9.

10. The organic light emitting diode according to claim 1, wherein the first organic layer comprises at least one of a hole transport layer and a hole injection layer, The second organic layer includes at least one of an electron transport layer and an electron injection layer.

11. An organic light emitting diode, comprising: a first electrode; a first organic layer disposed on the first electrode and having a first refractive index; a light-emitting layer disposed on the first organic layer and having a second refractive index; a second organic layer disposed on the light-emitting layer and having a third refractive index; as well as a second electrode disposed on the second organic layer, The first refractive index is greater than the third refractive index. 12 . The organic light emitting diode according to claim 11 , wherein the first refractive index is equal to or greater than the second refractive index.

13. The organic light emitting diode according to claim 11, further comprising: a third organic layer disposed between the first organic layer and the light-emitting layer, The fourth refractive index of the third organic layer is equal to or less than the first refractive index, and equal to or greater than the second refractive index.

14. The organic light emitting diode according to claim 11, The difference between the first refractive index and the second refractive index is smaller than the difference between the second refractive index and the third refractive index.

15. A display device, comprising: A substrate, the substrate comprising a first pixel region, a second pixel region and a third pixel region; as well as an organic light emitting diode disposed in the first pixel region, the second pixel region and the third pixel region, Any organic light emitting diode arranged in each pixel region includes: a first electrode; a second electrode arranged on the first electrode; a first organic layer arranged to contact the upper surface of the first electrode; a light emitting layer arranged on the first organic layer; and a second organic layer arranged on the light emitting layer and arranged to contact the lower surface of the second electrode, wherein a first refractive index of the first organic layer is equal to or greater than a second refractive index of the light emitting layer, The second refractive index of the light emitting layer is greater than the third refractive index of the second organic layer.

16. The display device according to claim 15, The difference between the first refractive index and the third refractive index is greater than 0.15 and less than 0.

5.

17. The display device according to claim 15, The ratio of the difference between the first refractive index and the second refractive index to the difference between the second refractive index and the third refractive index is greater than or equal to 4:21 and less than or equal to 16:

9.

18. The display device according to claim 15, wherein one of the plurality of organic light emitting diodes disposed in the first pixel region and the second pixel region further includes a third organic layer located between the first organic layer and the light emitting layer, The fourth refractive index of the third organic layer is equal to or less than the first refractive index of the first organic layer.

19. The display device according to claim 18, The organic light emitting diode disposed in the first pixel region emits red light, The organic light emitting diode disposed in the second pixel area emits green light, The organic light emitting diode disposed in the third pixel region emits blue light.

20. The display device according to claim 16, The difference between the first refractive index and the second refractive index is smaller than the difference between the second refractive index and the third refractive index.

21. The display device according to claim 18, Wherein the fourth refractive index is equal to or greater than the second refractive index.

22. The display device according to claim 15, The light-emitting layer of the organic light-emitting diode arranged in the third pixel area is directly arranged on the first organic layer.

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