Light emitting diode and display device including same

Abstract

The invention discloses a light emitting diode and a display device including the same. The display device includes: a substrate; a pixel electrode over the substrate; a counter electrode over the pixel electrode, and having a thickness between about # imgabs 0 # and about # imgabs 1 #; an emission layer between the pixel electrode and the counter electrode; a first functional layer between the pixel electrode and the emission layer; and a second functional layer between the emission layer and the counter electrode and having a thickness between about # imgabs2 # and about # imgabs3 #.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority and benefit of Korean Patent Application No. 10 - 2024 - 0007643, filed with the Korean Intellectual Property Office on January 17, 2024, the entire disclosure of which is incorporated herein by reference. Technical field

[0003] One or more embodiments relate to light - emitting diodes having an effectively extended lifespan and display devices including the light - emitting diodes. Background art

[0004] Among display devices, organic light - emitting display devices have attracted attention as next - generation display devices because they have aspects such as wide viewing angles, excellent contrast ratios, and fast response speeds.

[0005] As a display element, an organic light - emitting display device includes organic light - emitting diodes (OLEDs) each including a hole injection electrode, an electron injection electrode, and an organic emission layer formed therebetween. An organic light - emitting display device is a self - emissive display device that generates light as excitons generated by the recombination of holes injected from the hole injection electrode and electrons injected from the electron injection electrode in the organic emission layer transition from an excited state to a ground state.

[0006] The organic light - emitting display device, which is a self - emissive display device, does not require a separate light source and can therefore be driven at a low voltage and can be configured in a light - weight and thin form. In addition, the organic light - emitting display device has a suitable viewing angle, contrast ratio, response speed, etc., and thus, the application range of the organic light - emitting display device has expanded from personal portable devices such as mobile phones to televisions (TVs). Summary of the invention

[0007] One or more embodiments include light - emitting diodes having an effectively extended lifespan and display devices including the light - emitting diodes. The embodiments described herein are examples, and the embodiments of the present disclosure are not limited thereto.

[0008] Additional aspects will be set forth in part in the following description and in part will be obvious from the description, or may be learned by practice of the presented embodiments of the present disclosure.

[0009] According to one or more embodiments, a display device includes: a substrate; a pixel electrode above the substrate; a counter electrode above the pixel electrode and having a thickness of about to about a thickness between; an emission layer, between the pixel electrode and the counter electrode; a first functional layer, between the pixel electrode and the emission layer; and a second functional layer, between the emission layer and the counter electrode, and having a thickness between approximately and approximately between.

[0010] The second functional layer may include an electron transport layer having a thickness between approximately and approximately between.

[0011] The second functional layer may have a refractive index between approximately 2.0 and approximately 3.0.

[0012] The display device may further include: a cover layer, above the counter electrode.

[0013] The cover layer may have a refractive index between approximately 2.3 and approximately 3.0.

[0014] The display device may further include: a first optical functional layer, above the counter electrode, and having an uneven surface.

[0015] The display device may further include: a second optical functional layer, between the second functional layer and the counter electrode, and having an uneven surface.

[0016] The thickness of the first optical functional layer may be greater than the thickness of the second optical functional layer.

[0017] The emission layer may be configured to emit blue light, wherein the distance between the pixel electrode and the emission layer is between approximately and approximately between.

[0018] The emission layer may be configured to emit green light, wherein the distance between the pixel electrode and the emission layer is between approximately and approximately between.

[0019] The emission layer may be configured to emit red light, wherein the distance between the pixel electrode and the emission layer is between approximately and approximately between.

[0020] The pixel electrode may include a reflective electrode, wherein the counter electrode includes a transmissive electrode.

[0021] According to one or more embodiments, a display device includes: a substrate; a pixel electrode, above the substrate; a counter electrode, above the pixel electrode, and having a thickness between approximately and approximately a thickness between; an emission layer, between the pixel electrode and the counter electrode; a first functional layer, between the pixel electrode and the emission layer; and a second functional layer, between the emission layer and the counter electrode and having a refractive index between about 2.0 and about 3.0.

[0022] The display device may further include: a capping layer, above the counter electrode.

[0023] The capping layer may have a refractive index between about 2.3 and about 3.0.

[0024] The display device may further include: a first optical functional layer, above the counter electrode and having an uneven surface.

[0025] The display device may further include: a second optical functional layer, between the second functional layer and the counter electrode and having an uneven surface.

[0026] The thickness of the first optical functional layer may be greater than the thickness of the second optical functional layer.

[0027] According to one or more embodiments, a light-emitting diode includes: a pixel electrode; a counter electrode, above the pixel electrode and having a thickness between about and about ; an emission layer, between the pixel electrode and the counter electrode; a first functional layer, between the pixel electrode and the emission layer; and a second functional layer, between the emission layer and the counter electrode and having a thickness between about and about .

[0028] The second functional layer may have a refractive index between about 2.0 and about 3.0. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above and other aspects of specific embodiments of the present disclosure will become more apparent from the following description in conjunction with the drawings, in which:

[0030] Figure 1 is a schematic perspective view of a display device according to one or more embodiments;

[0031] Figure 2 is an equivalent circuit diagram of a pixel included in a display device according to one or more embodiments;

[0032] Figure 3 is a schematic cross-sectional view of a display device according to one or more embodiments;

[0033] Figure 4 schematically shows Figure 3 an enlarged view of a first light-emitting diode to a third light-emitting diode;

[0034] Figure 5 is a schematic cross-sectional view of a display device according to one or more embodiments;

[0035] Figure 6 is a schematic cross-sectional view of a display device according to one or more embodiments;

[0036] Figure 7 schematically shows according to one or more embodiments Figure 6 an enlarged view of a first light-emitting diode to a third light-emitting diode;

[0037] Figure 8 is a graph showing the results of surface plasmon polariton (SPP) simulation according to the thickness of a counter electrode;

[0038] Figure 9 is a graph obtained by measuring the luminance over time in embodiments where the counter electrode has different thicknesses; and

[0039] Figure 10 is a graph obtained by measuring transient electroluminescence (TEL) over time in embodiments where the counter electrode has different thicknesses. DETAILED DESCRIPTION

[0040] Aspects of some embodiments of the present disclosure and methods for implementing them can be more easily understood by referring to the detailed description of the embodiments and the accompanying drawings. The described embodiments are provided as examples so that the present disclosure will be thorough and complete, and will fully convey the aspects of the present disclosure to those skilled in the art. Accordingly, processes, elements, and techniques that are redundant, not relevant to the description of the embodiments, or unnecessary for those of ordinary skill in the art to fully understand the aspects of the present disclosure may be omitted. Unless otherwise noted, throughout the drawings and the written description, the same reference numerals, characters, or combinations thereof represent the same elements, and thus their repeated description may be omitted.

[0041] The described embodiments may have various modifications and may be embodied in different forms and should not be construed as limited to the embodiments illustrated herein. The use of "may", "can", or "may not" when describing the embodiments corresponds to one or more embodiments of the present disclosure.

[0042] In view of the overall content of the present disclosure, those of ordinary skill in the art will understand that the present disclosure covers all modifications, equivalents, and alternatives within the spirit and scope of the present disclosure. Each of the features of the embodiments of the present disclosure may be partially or wholly combined with each other, and various tight connections and operations are possible technically, and unless otherwise stated or implied, the various embodiments may be implemented independently of each other or may be implemented in an associated manner together.

[0043] In the accompanying drawings, for clarity and / or for the purposes of description, the relative dimensions of elements, layers, and regions may be exaggerated and / or simplified. Additionally, the use of cross-hatching and / or shading in the drawings is generally provided to clarify the boundaries between adjacent elements. Thus, unless otherwise specified, the presence or absence of cross-hatching or shading does not convey or indicate any preference or requirement regarding a particular material, material properties, dimensions, ratios, commonality between illustrated elements, and / or any other characteristics, attributes, properties, etc. of the elements.

[0044] Various embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of the embodiments and / or intermediate structures. Thus, for example, variations in the shapes of the illustrations due to manufacturing techniques and / or tolerances are to be expected. Additionally, the specific structural or functional descriptions disclosed herein are merely illustrative for the purpose of describing embodiments in accordance with the concepts of the present disclosure. Accordingly, the embodiments disclosed herein should not be construed as being limited to the shapes of the illustrations of elements, layers, or regions, but include deviations in shapes resulting from, for example, manufacturing.

[0045] For example, an implantation region illustrated as rectangular generally has arcuate or curved features at its edges and / or a gradient of implant concentration, rather than a binary change from the implanted region to the non-implanted region. Similarly, a buried region formed by implantation can result in some implantation in the region between the buried region and the surface through which the implantation occurs.

[0046] For ease of explanation, spatially relative terms such as "below", "beneath", "under", "lower side", "underneath", "above", "on", and "upper side" may be used herein to describe the relationship between one element or feature and another (some) element or feature as shown in the drawings. It will be understood that, in addition to the orientation depicted in the figures, spatially relative terms are intended to encompass different orientations of the device during use or operation. For example, if the device in the figures is flipped, an element described as "below", "beneath", or "underneath" other elements or features will then be oriented "above" the other elements or features. Thus, the example terms "below" and "beneath" can encompass both an above and a below orientation. The device may be otherwise oriented (e.g., rotated 90 degrees or in other orientations), and the spatially relative descriptors used herein should be interpreted accordingly. Similarly, when a first part is described as being disposed "on" a second part, this indicates that the first part is disposed on the upper side or the lower side of the second part based on the direction of gravity, and is not limited to its upper side.

[0047] In addition, the phrase "in a plan view" means when viewing the object part from above, and the phrase "in a schematic cross-sectional view" means when viewing a schematic cross-section taken by vertically cutting the object part from the side. The term "overlap" or "overlapping" means that the first object can be above, below, or beside the second object, and vice versa. Additionally, the term "overlap" can include stacking, facing, extending over, covering, or partially covering, or any other suitable term that one of ordinary skill in the art would appreciate and understand. The expression "not overlapping" can include meanings such as "separate from", "set aside", or "offset from", as well as any other suitable equivalents that one of ordinary skill in the art would appreciate and understand. The term "facing" can mean that the first object can be directly or indirectly opposite the second object. In the case where a third object is between the first object and the second object, the first object and the second object can be understood to be indirectly opposite each other, although still facing each other.

[0048] It will be understood that when an element, layer, region, or component is referred to as being "formed on", "on", "connected to", or "(operatively or communicatively) coupled to" another element, layer, region, or component, it can be directly formed on, directly on, directly connected to, or directly coupled to the other element, layer, region, or component, or indirectly formed on, indirectly on, indirectly connected to, or indirectly coupled to the other element, layer, region, or component, such that there can be one or more intervening elements, layers, regions, or components. Additionally, this can be collectively referred to as directly or indirectly coupling or connecting and integrally or non-integrally coupling or connecting. For example, when a layer, region, or component is referred to as being "electrically connected" or "electrically coupled" to another layer, region, or component, it can be directly electrically connected or coupled to the other layer, region, or component, or there can be one or more intervening layers, regions, or components. One or more intervening components can include switches, resistors, and / or capacitors, etc. When describing an embodiment, unless explicitly described as a direct connection, the expression of connection indicates an electrical connection, and "direct connection / direct coupling" or "directly on" means that one component is directly connected or directly coupled to another component or directly on another component, without intervening components.

[0049] In addition, in this specification, when a part of a layer, film, region, plate, etc. is formed on another part, the forming direction is not limited to the upward direction, but includes forming the part on a side surface or in a downward direction. Conversely, when a part of a layer, film, region, plate, etc. is formed "under" another part, this includes not only the case where the part is "directly" "below" the other part, but also the case where there is another part between the part and the other part. At the same time, other expressions describing the relationship between components such as "between", "directly between", "adjacent to", and "directly adjacent to" can be similarly interpreted. It will be understood that when an element or layer is referred to as being "between" two elements or layers, it can be the only element or layer between the two elements or layers, or there can also be one or more intervening elements or layers.

[0050] For the purposes of the present disclosure, expressions such as "at least one of", "any one of", or "one or more of" when following a list of elements modify the entire list of elements and not individual elements of the list. For example, "at least one of X, Y, and Z" and "at least one selected from the group consisting of X, Y, and Z" can be interpreted as only X, only Y, only Z, any combination of two or more of X, Y, and Z, such as for example XYZ, XY, YZ, and XZ or any variation thereof. Similarly, the expression "at least one of A and B" can include A, B, or A and B. As used herein, "or" generally means "and / or", and the term "and / or" includes any and all combinations of one or more of the associated listed items. For example, the expression "A and / or B" can include A, B, or A and B. Similarly, expressions such as "at least one of", "a plurality of", "one of", and other prepositional phrases when before / after a list of elements modify the entire list of elements and not individual elements of the list.

[0051] It will be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms do not correspond to a specific order, position, or superiority, and are only used to distinguish one element, component, region, layer, or section from another. Thus, a first element, component, region, layer, or section described below may be referred to as a second element, component, region, layer, or section without departing from the spirit and scope of the present disclosure. Referring to an element as a "first" element does not require or imply the existence of a second element or other elements. The terms "first", "second", etc. may also be used herein to distinguish different categories or sets of elements. For the sake of brevity, the terms "first", "second", etc. may respectively represent "first category (or first set)", "second category (or second set)", etc.

[0052] In the examples, the x-direction, y-direction, and / or z-direction are not limited to the directions corresponding to the three axes of a rectangular coordinate system and can be interpreted in a broad sense. For example, the x-direction, y-direction, and z-direction can be perpendicular to each other, or can represent different directions that are not perpendicular to each other. The same applies to the first direction, second direction, and / or third direction.

[0053] The terms used herein are for the purpose of describing embodiments only and are not intended to limit the present disclosure. As used herein, the singular form "a" is also intended to include the plural form, and the plural form is also intended to include the singular form, unless the context clearly indicates otherwise. It will be further understood that when used in this specification, the terms "comprising," "having," and "including" specify the presence of the stated features, wholes, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or groups thereof.

[0054] As used herein, the terms "substantially," "about," "approximately," and similar terms are used as terms of approximation and not of degree, and are intended to account for the inherent deviations in the values measured or calculated that would be recognized by a person of ordinary skill in the art. For example, "substantially" can include a range of ±5% of the corresponding value. Taking into account the measurements discussed and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system), "about" or "approximately" as used herein includes the stated value and means within an acceptable deviation of the particular value as determined by a person of ordinary skill in the art. For example, "about" can mean within one or more standard deviations, or within ±30%, ±20%, ±10%, ±5% of the stated value. Further, when describing embodiments of the present disclosure, "may" refers to "one or more embodiments of the present disclosure."

[0055] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by a person of ordinary skill in the technical field to which this disclosure belongs. It will be further understood that terms (e.g., terms defined in a commonly used dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and / or this specification, and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0056] Figure 1 is a schematic perspective view of a display device 1 according to one or more embodiments.

[0057] Reference Figure 1, the display device 1 may include a display area DA for displaying an image and a non-display area NDA that is a peripheral area where no image is displayed. In one or more embodiments, the non-display area NDA (e.g., in a plan view or in a plane defined by the x-direction and the y-direction) may completely surround the display area DA. In other words, it can be understood that the substrate 100 included in the display device 1 (see Figure 3 ) has a display area DA and a non-display area NDA.

[0058] The display device 1 may include a plurality of pixels P arranged in the display area DA. The display device 1 may provide an image by using light emitted from the plurality of pixels P. Each of the plurality of pixels P may include a display element such as Figure 2 the light-emitting diode LED shown in. Each pixel P may emit, for example, red light, green light, blue light, or white light through the light-emitting diode LED. Hereinafter, in this specification, the pixel P refers to a sub-pixel that emits light of different colors, and each pixel P may be, for example, a sub-pixel that emits red (R) light, green (G) light, or blue (B) light.

[0059] The non-display area NDA may be an area where no pixel P is arranged. A driver or the like for supplying an electrical signal or power to the pixel P may be arranged in the non-display area NDA. In the non-display area NDA, various electronic devices, pads to which a printed circuit board or the like can be electrically connected may be arranged. The pads may be arranged to be separated from each other in the non-display area NDA and may be electrically connected to a printed circuit board or an integrated circuit device.

[0060] Although Figure 1 the display device 1 having a quadrangular display area DA is shown, the present disclosure is not limited thereto. For example, the shape of the display area DA may be circular, elliptical, or a polygon such as a triangle or a pentagon.

[0061] Figure 2 is an equivalent circuit diagram of a pixel P included in a display device according to one or more embodiments.

[0062] Referring to Figure 2 , the pixel P may include a pixel circuit PC connected to a scan line SL and a data line DL and a light-emitting diode LED connected to the pixel circuit PC.

[0063] The pixel circuit PC may include a driving thin-film transistor T1, a switching thin-film transistor T2, and a storage capacitor Cst.

[0064] The switching thin-film transistor T2 may be configured to transmit a data signal Dm input through the data line DL to the driving thin-film transistor T1 according to a scan signal Sn input through the scan line SL.

[0065] The storage capacitor Cst can be connected to the switching thin-film transistor T2 and the driving voltage line PL, and can store the voltage difference between the voltage received from the switching thin-film transistor T2 and the first power supply voltage (or driving voltage) ELVDD applied to the driving voltage line PL.

[0066] The driving thin-film transistor T1 can be connected to the driving voltage line PL and the storage capacitor Cst, and can be configured to control the driving current flowing from the driving voltage line PL to the light-emitting diode LED according to the voltage stored in the storage capacitor Cst. The light-emitting diode LED can emit light with a specific brightness according to the driving current. The first electrode (e.g., anode) of the light-emitting diode LED can be connected to the pixel circuit PC, and the second electrode (e.g., cathode) of the light-emitting diode LED can receive the second power supply voltage ELVSS.

[0067] Although Figure 2 the figure illustrates the case where the pixel circuit PC includes two thin-film transistors and one storage capacitor, the present disclosure is not limited thereto. For example, the pixel circuit PC can include three or more thin-film transistors or two or more capacitors. The number and circuit design of the thin-film transistors and capacitors in the pixel circuit PC can be changed in various ways.

[0068] In Figure 2 each of the driving thin-film transistor T1 and the switching thin-film transistor T2 is shown as including a p-channel metal-oxide-semiconductor field-effect transistor (p-channel MOSFET (PMOS)). However, the present disclosure is not limited thereto. In one or more embodiments, one or both of the driving thin-film transistor T1 and the switching thin-film transistor T2 can include an n-channel MOSFET (NMOS). In one or more embodiments, some of the multiple thin-film transistors included in the pixel circuit PC can include PMOS, and the remaining thin-film transistors of the multiple thin-film transistors can include NMOS.

[0069] Figure 3 is a schematic cross-sectional view of a display device 1 according to one or more embodiments. Figure 4 schematically shows Figure 3 an enlarged view of the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3.

[0070] Refer to Figure 3, the display device 1 may include a first pixel P1, a second pixel P2, and a third pixel P3 that emit light having respective different wavelengths. The first pixel P1, the second pixel P2, and the third pixel P3 may include a first light-emitting diode LED1, a second light-emitting diode LED2, and a third light-emitting diode LED3, respectively. In one or more embodiments, the first light-emitting diode LED1 may emit light having a blue wavelength, the second light-emitting diode LED2 may emit light having a green wavelength, and the third light-emitting diode LED3 may emit light having a red wavelength.

[0071] The display device 1 may include a substrate 100, a pixel circuit layer PCL on the substrate 100, first to third light-emitting diodes LED1, LED2, and LED3 on the pixel circuit layer PCL, and a packaging member 300 on the first to third light-emitting diodes LED1, LED2, and LED3.

[0072] The substrate 100 may include glass, metal, or a polymer resin. The polymer resin may include, for example, polyethersulfone, polyacrylate, polyetherimide, polyethylene naphthalate, polyethylene terephthalate, polyphenylene sulfide, polyarylate, polyimide, polycarbonate, cellulose acetate propionate, or a mixture thereof. The substrate 100 may have various modifications, such as having a multilayer structure including two layers containing a polymer resin and a barrier layer located between the two layers and containing an inorganic material (e.g., silicon oxide (SiO x ), silicon nitride (SiN x ), or silicon oxynitride (SiO x N y ))).

[0073] The pixel circuit layer PCL may include first to third pixel circuits PC1, PC2, and PC3 and an insulating layer. As previously referenced Figure 2 described, each of the first to third pixel circuits PC1, PC2, and PC3 may include a thin-film transistor and a storage capacitor. As one or more embodiments, Figure 3 illustrates a thin-film transistor TFT and a storage capacitor Cst provided in each of the first to third pixel circuits PC1, PC2, and PC3.

[0074] The pixel circuit layer PCL may include a buffer layer 101, a first gate insulating layer 103, a second gate insulating layer 105, an interlayer insulating layer 107, a thin-film transistor TFT, and a via insulating layer 110.

[0075] The buffer layer 101 may be located on the substrate 100 to flatten the upper surface of the substrate 100. The buffer layer 101 may be used to block impurities, moisture, or external gases from entering the display device 1 from the outside. The buffer layer 101 may include an inorganic insulating material such as silicon oxide (SiO x ), silicon nitride (SiN x ), or silicon oxynitride (SiO x N y ). The buffer layer 101 may include a single-layer or multi-layer structure including the aforementioned inorganic insulating material.

[0076] Each of the first pixel circuit to the third pixel circuit PC1, PC2, and PC3 may include at least one thin film transistor TFT and a storage capacitor Cst. The thin film transistor TFT may include a semiconductor layer Act, a gate electrode GE, a source electrode SE, and a drain electrode DE.

[0077] The semiconductor layer Act may be located on the buffer layer 101. The semiconductor layer Act may include an oxide semiconductor and / or a silicon semiconductor. When the semiconductor layer Act is formed of an oxide semiconductor, the semiconductor layer Act may include an oxide of at least one material selected from the group including, for example, indium (In), gallium (Ga), tin (Sn), zirconium (Zr), vanadium (V), hafnium (Hf), cadmium (Cd), germanium (Ge), chromium (Cr), titanium (Ti), and zinc (Zn). For example, the semiconductor layer Act may be an InSnZnO (ITZO) semiconductor layer or an InGaZnO (IGZO) semiconductor layer, etc. When the semiconductor layer Act is formed of a silicon semiconductor, the semiconductor layer Act may include, for example, amorphous silicon or low temperature polycrystalline silicon (LTPS). A barrier layer that blocks or reduces the penetration of external air may be further included between the substrate 100 and the buffer layer 101.

[0078] The first gate insulating layer 103 may be located on the buffer layer 101. The first gate insulating layer 103 may be located on the semiconductor layer Act. The first gate insulating layer 103 may include an inorganic insulating material such as silicon oxide (SiO x ), silicon nitride (SiN x ), silicon oxynitride (SiO x N y ), aluminum oxide (Al2O3), titanium oxide (TiO2), tantalum oxide (Ta2O5), hafnium oxide (HfO2), or zinc oxide (ZnO x , which may be ZnO and / or ZnO2).

[0079] The gate electrode GE may be located on the semiconductor layer Act. The first gate insulating layer 103 may be between the gate electrode GE and the semiconductor layer Act. The gate electrode GE may overlap with the channel region of the semiconductor layer Act. The gate electrode GE may include a low-resistance metal material. For example, the gate electrode GE may include a single layer or multiple layers containing one or more metals selected from aluminum (Al), platinum (Pt), palladium (Pd), silver (Ag), magnesium (Mg), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li), calcium (Ca), molybdenum (Mo), titanium (Ti), tungsten (W), and copper (Cu).

[0080] The second gate insulating layer 105 may be located on the first gate insulating layer 103. The second gate insulating layer 105 may cover the gate electrode GE. Similar to the first gate insulating layer 103, the second gate insulating layer 105 may include an inorganic insulating material such as silicon oxide (SiO x ), silicon nitride (SiN x ), silicon oxynitride (SiO x N y ), aluminum oxide (Al2O3), titanium oxide (TiO2), tantalum oxide (Ta2O5), hafnium oxide (HfO2), or zinc oxide (ZnO x , which may be ZnO and / or ZnO2).

[0081] The second capacitor electrode CE2 of the storage capacitor Cst may be located on the second gate insulating layer 105. In one or more embodiments, the second capacitor electrode CE2 may overlap with the gate electrode GE. The second gate insulating layer 105 may be between the gate electrode GE and the second capacitor electrode CE2. The gate electrode GE and the second capacitor electrode CE2 that overlap with each other may form the storage capacitor Cst. That is, the gate electrode GE may function as the first capacitor electrode CE1 of the storage capacitor Cst. As Figure 3 shown, the storage capacitor Cst and the thin film transistor TFT may overlap with each other, but it is not limited thereto. In one or more other embodiments, the storage capacitor Cst and the thin film transistor TFT may not overlap with each other.

[0082] The interlayer insulating layer 107 may be located on the second gate insulating layer 105. The interlayer insulating layer 107 may cover the second capacitor electrode CE2. The interlayer insulating layer 107 may include an inorganic insulating material such as silicon oxide (SiO x ), silicon nitride (SiN x ), silicon oxynitride (SiO x N y ), aluminum oxide (Al2O3), titanium oxide (TiO2), tantalum oxide (Ta2O5), hafnium oxide (HfO2), or zinc oxide (ZnO x, an inorganic insulating material which can be ZnO and / or ZnO2). The interlayer insulating layer 107 can be a single layer or multiple layers including the above inorganic insulating material.

[0083] The source electrode SE and the drain electrode DE can each be located on the interlayer insulating layer 107. The source electrode SE and the drain electrode DE can be electrically connected to the semiconductor layer Act through contact holes formed in the first gate insulating layer 103, the second gate insulating layer 105, and the interlayer insulating layer 107. The source electrode SE and the drain electrode DE can each include a material with good electrical conductivity. At least one of the source electrode SE and the drain electrode DE can include a conductive material containing molybdenum (Mo), aluminum (Al), copper (Cu), or titanium (Ti), etc., and can include a multi-layer or single layer containing the above conductive material. In one or more embodiments, at least one of the source electrode SE and the drain electrode DE can have a multi-layer structure including a Ti / Al / Ti layer.

[0084] The via insulating layer 110 can be located on the interlayer insulating layer 107. The via insulating layer 110 can be located on the source electrode SE and the drain electrode DE. The via insulating layer 110 is shown as a single layer, but is not limited thereto, and can be formed as multiple layers. The via insulating layer 110 can be an organic insulating layer including an organic material. The via insulating layer 110 can flatten the upper surfaces of the first pixel circuit to the third pixel circuit PC1, PC2, and PC3, thereby flattening the surface on which the first light-emitting diode to the third light-emitting diode LED1, LED2, and LED3 will be arranged.

[0085] The first light-emitting diode to the third light-emitting diode LED1, LED2, and LED3 can be organic light-emitting diodes including an organic emission layer.

[0086] The first light-emitting diode to the third light-emitting diode LED1, LED2, and LED3 can be electrically connected to the first pixel circuit to the third pixel circuit PC1, PC2, and PC3 located between the substrate 100 and the first light-emitting diode to the third light-emitting diode LED1, LED2, and LED3 in a direction perpendicular to the upper surface of the substrate 100 (e.g., the z direction).

[0087] Each of the first light-emitting diode to the third light-emitting diode LED1, LED2, and LED3 may have a stacked structure including a pixel electrode as a hole injection electrode, an intermediate layer, and a counter electrode as an electron injection electrode. The first light-emitting diode LED1 may include a first pixel electrode 210a, a first intermediate layer 220a, and a counter electrode 230. The first pixel electrode 210a may be electrically connected to the first pixel circuit PC1. The second light-emitting diode LED2 may include a second pixel electrode 210b, a second intermediate layer 220b, and a counter electrode 230. The second pixel electrode 210b may be electrically connected to the second pixel circuit PC2. The third light-emitting diode LED3 may include a third pixel electrode 210c, a third intermediate layer 220c, and a counter electrode 230. The third pixel electrode 210c may be electrically connected to the third pixel circuit PC3.

[0088] The first pixel electrode to the third pixel electrode 210a, 210b, and 210c may be located on the via hole insulating layer 110. The first pixel electrode to the third pixel electrode 210a, 210b, and 210c may be electrically connected to thin film transistors TFT provided in the first pixel circuit to the third pixel circuit PC1, PC2, and PC3, respectively. For example, the first pixel electrode 210a may be electrically connected to the thin film transistor TFT of the first pixel circuit PC1 through a contact hole in the via hole insulating layer 110.

[0089] The first pixel electrode to the third pixel electrode 210a, 210b, and 210c may be a transmissive electrode, a semi-transmissive electrode, or a reflective electrode. When the first pixel electrode to the third pixel electrode 210a, 210b, and 210c are transmissive electrodes, the first pixel electrode to the third pixel electrode 210a, 210b, and 210c may each include a transparent conductive material such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium oxide (In2O3), indium gallium oxide (IGO), or aluminum zinc oxide (AZO). When the first pixel electrode to the third pixel electrode 210a, 210b, and 210c are semi-transmissive electrodes or reflective electrodes, the first pixel electrode to the third pixel electrode 210a, 210b, and 210c may each include a reflective layer containing silver (Ag), magnesium (Mg), aluminum (Al), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li), calcium (Ca), or a compound thereof.

[0090] The first to third pixel electrodes 210a, 210b, and 210c may each have a single-layer structure including a single layer or a multi-layer structure including multiple layers. In one or more embodiments, the first to third pixel electrodes 210a, 210b, and 210c may be reflective electrodes and may have a stacked structure including at least one reflective layer and at least one transparent conductive layer. For example, the first to third pixel electrodes 210a, 210b, and 210c may each have a three-layer structure in which a transparent conductive layer including a transparent conductive oxide is located above and below the reflective layer. For example, the first to third pixel electrodes 210a, 210b, and 210c may each have a stacked structure including an ITO / Ag / ITO layer.

[0091] The pixel defining layer 130 may be located on the via hole insulating layer 110. The pixel defining layer 130 may be located on the first to third pixel electrodes 210a, 210b, and 210c and may include a first pixel opening OP1 exposing a part of the first pixel electrode 210a, a second pixel opening OP2 exposing a part of the second pixel electrode 210b, and a third pixel opening OP3 exposing a part of the third pixel electrode 210c. That is, at least a part of the upper surface of the first to third pixel electrodes 210a, 210b, and 210c may be exposed by the first to third pixel openings OP1, OP2, and OP3 defined in the pixel defining layer 130. The emission region of each pixel may be defined by the first to third pixel openings OP1, OP2, and OP3 exposing at least a part of the first to third pixel electrodes 210a, 210b, and 210c. The pixel defining layer 130 may reduce or prevent the possibility of arcing at the edges of the first to third pixel electrodes 210a, 210b, and 210c by increasing the distance between the edge of each of the first to third pixel electrodes 210a, 210b, and 210c and the counter electrode 230. The pixel defining layer 130 may include an organic material such as polyimide or hexamethyldisiloxane (HMDSO).

[0092] The counter electrode 230 may be located on the first to third pixel electrodes 210a, 210b, and 210c to face the first to third pixel electrodes 210a, 210b, and 210c. Different from the first to third pixel electrodes 210a, 210b, and 210c that are patterned to be separated from each other, the counter electrode 230 may be integrally formed as a whole on the substrate 100. That is, the counter electrode 230 may be provided over a plurality of pixels located in the display area DA (see Figure 1 ).

[0093] In one or more embodiments, the counter electrode 230 may be provided as a transmissive electrode. The transmissive electrode may mean that the counter electrode 230 is provided as a transmissive or semi-transmissive electrode. In one or more embodiments, the display device 1 may be a top-emission display device in which the light emitted from the first emission layer to the third emission layers 222a, 222b, and 222c passes through the counter electrode 230 and is emitted to the outside.

[0094] The counter electrode 230 may include, for example, silver (Ag), magnesium (Mg), aluminum (Al), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li), calcium (Ca), or an alloy thereof, or lithium fluoride (LiF). The counter electrode 230 may include a single layer or multiple layers.

[0095] Since the first pixel electrode to the third pixel electrodes 210a, 210b, and 210c are provided as reflective electrodes, and the counter electrode 230 is provided as a transmissive electrode, the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3 may form a microcavity.

[0096] The first intermediate layer to the third intermediate layers 220a, 220b, and 220c may be respectively located on the first pixel electrode to the third pixel electrodes 210a, 210b, and 210c. The first intermediate layer 220a may be between the first pixel electrode 210a and the counter electrode 230. The second intermediate layer 220b may be between the second pixel electrode 210b and the counter electrode 230. The third intermediate layer 220c may be between the third pixel electrode 210c and the counter electrode 230. The first intermediate layer to the third intermediate layers 220a, 220b, and 220c may be respectively located in the first pixel opening to the third pixel openings OP1, OP2, and OP3 of the pixel defining layer 130.

[0097] The first intermediate layer 220a may include a first emission layer 222a that emits light having a first color, a 1-1 functional layer 221a located below the first emission layer 222a, and a 2-1 functional layer 223a located above the first emission layer 222a. The second intermediate layer 220b may include a second emission layer 222b that emits light having a second color, a 1-2 functional layer 221b located below the second emission layer 222b, and a 2-2 functional layer 223b located above the second emission layer 222b. The third intermediate layer 220c may include a third emission layer 222c that emits light having a third color, a 1-3 functional layer 221c located below the third emission layer 222c, and a 2-3 functional layer 223c located above the third emission layer 222c.

[0098] In one or more embodiments, the first emission layer to the third emission layer 222a, 222b, and 222c may emit light having different wavelengths. For example, the first emission layer 222a may emit light having a blue wavelength, the second emission layer 222b may emit light having a green wavelength, and the third emission layer 222c may emit light having a red wavelength. The first emission layer to the third emission layer 222a, 222b, and 222c may be patterned and provided for each pixel.

[0099] The first emission layer to the third emission layer 222a, 222b, and 222c may each include a host and a dopant. For example, the dopant may include at least one of a phosphorescent dopant and a fluorescent dopant.

[0100] The first functional layer 221a may be between the first pixel electrode 210a and the first emission layer 222a. The second functional layer 221b may be between the second pixel electrode 210b and the second emission layer 222b. The third functional layer 221c may be between the third pixel electrode 210c and the third emission layer 222c. The first functional layer 221a, the second functional layer 221b, and the third functional layer 221c may be integrally formed as a single body over a plurality of pixels on the substrate 100. However, in this case, some of the layers included in the first functional layer 221a, the second functional layer 221b, and the third functional layer 221c (e.g., the emission assist layer) may be patterned and provided for each pixel. The first functional layer 221a, the second functional layer 221b, and the third functional layer 221c may be respectively referred to as the lower functional layer of the first light-emitting diode LED1, the lower functional layer of the second light-emitting diode LED2, and the lower functional layer of the third light-emitting diode LED3.

[0101] The first functional layer 221a, the second functional layer 221b, and the third functional layer 221c may be defined as hole-transporting regions for transporting holes. Each of the hole-transporting regions may have a single-layer structure including a single layer containing a single material, may have a single-layer structure including a single layer containing a plurality of different materials, or may have a multi-layer structure including a plurality of layers containing a plurality of different materials.

[0102] In one or more embodiments, the hole-transporting region may include at least one layer selected from a hole injection layer (HIL), a hole transport layer (HTL), an emission assist layer, and an electron blocking layer (EBL). In one or more embodiments, the thicknesses of the HIL, HTL, emission assist layer, and EBL included in each of the first functional layer 221a, the second functional layer 221b, and the third functional layer 221c may be provided independently of each other.

[0103] For example, the hole transport region may have a single-layer structure including a single layer containing a plurality of different materials, or may have a multi-layer structure including HIL / HTL, HIL / HTL / emission assist layer, HIL / emission assist layer, HTL / emission assist layer, or HIL / HTL / EBL sequentially stacked on a pixel electrode (e.g., one of the first pixel electrode to the third pixel electrodes 210a, 210b, and 210c). However, the present disclosure is not limited thereto.

[0104] The emission assist layer improves the light emission efficiency by compensating for the optical resonance distance according to the wavelength of the light emitted from the emission layer, and the EBL reduces or prevents the injection of electrons from the electron transport region. The emission assist layer and the EBL may include the materials described above. The thickness of the emission assist layer may be provided independently for each pixel.

[0105] The 2-1 functional layer 223a may be between the first emission layer 222a and the counter electrode 230. The 2-2 functional layer 223b may be between the second emission layer 222b and the counter electrode 230. The 2-3 functional layer 223c may be between the third emission layer 222c and the counter electrode 230. The 2-1 functional layer 223a, the 2-2 functional layer 223b, and the 2-3 functional layer 223c may be integrally formed as a whole over a plurality of pixels on the substrate 100. The 2-1 functional layer 223a, the 2-2 functional layer 223b, and the 2-3 functional layer 223c may be respectively referred to as the upper functional layer of the first light-emitting diode LED1, the upper functional layer of the second light-emitting diode LED2, and the upper functional layer of the third light-emitting diode LED3.

[0106] The 2-1 functional layer 223a, the 2-2 functional layer 223b, and the 2-3 functional layer 223c may be defined as an electron transport region for transporting electrons.

[0107] Each of the electron transport regions may have a single-layer structure including a single layer containing a single material, may have a single-layer structure including a single layer containing a plurality of different materials, or may have a multi-layer structure including a plurality of layers containing a plurality of different materials.

[0108] The electron transport region may include, but is not limited to, at least one layer selected from a buffer layer, a hole blocking layer, an electron control layer, an electron transport layer (ETL), and an electron injection layer (EIL).

[0109] For example, the electron transport region may have a structure including ETL / EIL, hole blocking layer / ETL / EIL, electron control layer / ETL / EIL, or buffer layer / ETL / EIL sequentially stacked on an emission layer (e.g., one of the first emission layer to the third emission layers 222a, 222b, and 222c). However, the present disclosure is not limited thereto.

[0110] The thicknesses of the buffer layer, hole blocking layer, electron control layer, ETL, and EIL included in each of the second - 1 functional layer 223a, second - 2 functional layer 223b, and second - 3 functional layer 223c can be provided independently of each other.

[0111] In one or more embodiments, the display device 1 may further include a capping layer 250 located on the counter electrode 230. The capping layer 250 can increase the reflectivity of the counter electrode 230, thereby increasing the resonance efficiency of the resonance structure formed between the first pixel electrode to the third pixel electrodes 210a, 210b, and 210c and the counter electrode 230. As the resonance efficiency of the resonance structure increases, the light extraction efficiency of the display device 1 can be improved.

[0112] In one or more embodiments, the display device 1 may further include a first optical functional layer 260 located on the first light - emitting diode to the third light - emitting diodes LED1, LED2, and LED3. The first optical functional layer 260 can be located on the counter electrode 230. In one or more embodiments, the first optical functional layer 260 can be located on the capping layer 250. In one or more embodiments, the first optical functional layer 260 is shown between the capping layer 250 and the encapsulation member 300, but the present disclosure is not limited thereto. The position where the first optical functional layer 260 is provided can vary depending on the embodiment.

[0113] The first optical functional layer 260 may have an uneven surface or an irregular surface. In the present specification, the fact that the first optical functional layer 260 has an uneven surface (or an irregular surface) may mean that the surface roughness of the first optical functional layer 260 is relatively greater than the surface roughness of the components in contact with or adjacent to the first optical functional layer 260. For example, the surface roughness of the first optical functional layer 260 can be greater than the surface roughness of the capping layer 250. For example, the surface roughness of the first optical functional layer 260 can be greater than the surface roughness of the counter electrode 230. In one or more embodiments, the first optical functional layer 260 may include an organic material.

[0114] The encapsulation member 300 can be located on the first light - emitting diode to the third light - emitting diodes LED1, LED2, and LED3 to seal the first light - emitting diode to the third light - emitting diodes LED1, LED2, and LED3. The encapsulation member 300 can be located on the capping layer 250 and the first optical functional layer 260. The encapsulation member 300 may include at least one inorganic encapsulation layer and at least one organic encapsulation layer. In one or more embodiments, the encapsulation member 300 may include a first inorganic encapsulation layer, an organic encapsulation layer, and a second inorganic encapsulation layer stacked in sequence.

[0115] The first inorganic encapsulation layer and the second inorganic encapsulation layer may each include one or more inorganic insulating materials. The inorganic insulating materials may include aluminum oxide, tantalum oxide, hafnium oxide, zinc oxide, silicon oxide, silicon nitride, or / and silicon oxynitride. The organic encapsulation layer may include polymer materials. The polymer materials may include acrylic resins, epoxy resins, polyimides, polyethylene, etc. The acrylic resin may include, for example, polymethyl methacrylate or polyacrylic acid, etc.

[0116] Reference Figure 4 , the distance between the pixel electrode and the emission layer of each of the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3 can be changed. That is, the distance D1 between the first pixel electrode 210a and the first emission layer 222a, the distance D2 between the second pixel electrode 210b and the second emission layer 222b, and the distance D3 between the third pixel electrode 210c and the third emission layer 222c can be different from each other. For example, the distance D1 between the first pixel electrode 210a and the first emission layer 222a can be between about and about . For example, the distance D2 between the second pixel electrode 210b and the second emission layer 222b can be between about and about . For example, the distance D3 between the third pixel electrode 210c and the third emission layer 222c can be between about and about .

[0117] The thickness TH11 of the 2-1 functional layer 223a can be, for example, in the range from about to about . The thickness of the ETL included in the 2-1 functional layer 223a can be, for example, in the range from about to about . The thickness of the ETL included in the 2-1 functional layer 223a can be, for example, in the range from about to about . When the thickness TH11 of the 2-1 functional layer 223a exceeds about , the lifetimes of the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3 may be shortened.

[0118] The thicknesses of the upper functional layers of the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3 can be substantially the same. In one or more embodiments, the thickness TH11 of the 2-1 functional layer 223a of the first light-emitting diode LED1, the thickness TH12 of the 2-2 functional layer 223b of the second light-emitting diode LED2, and the thickness TH13 of the 2-3 functional layer 223c of the third light-emitting diode LED3 can be substantially the same. The thickness TH11 of the 2-1 functional layer 223a can refer to the distance between the first emission layer 222a and the counter electrode 230, the thickness TH12 of the 2-2 functional layer 223b can refer to the distance between the second emission layer 222b and the counter electrode 230, and the thickness TH13 of the 2-3 functional layer 223c can refer to the distance between the third emission layer 222c and the counter electrode 230. In one or more embodiments, the thicknesses of the ETLs included in the 2-1 functional layer 223a, the 2-2 functional layer 223b, and the 2-3 functional layer 223c can be substantially the same.

[0119] Since the thickness of the ETL in each of the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3 is about to about Therefore, the distance between each of the first emission layer to the third emission layers 222a, 222b, and 222c and the counter electrode 230 can be relatively reduced to increase surface plasmon polaritons (SPPs). When the SPPs increase, excessive exciton energy may decrease, thereby increasing the lifespan of the light-emitting diodes. Thus, when the thickness of the ETL is about to about the lifespan of the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3 can be effectively increased. When the thickness of the ETL is less than about the ETL may not function as an electron transport layer. When the thickness of the ETL exceeds about the SPPs may decrease, and the lifespan of the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3 may decrease.

[0120] The thickness TH2 of the counter electrode 230 can be in the range from about to about When the thickness TH2 of the counter electrode 230 is about or greater, the lifespan of the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3 can be effectively increased. When the thickness TH2 of the counter electrode 230 exceeds the light extraction efficiency of the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3 may decrease.

[0121] Equation 1

[0122]

[0123] c = the speed of light, ω = the angular frequency of light, ε d = the dielectric constant of the organic material, and ε m = the dielectric constant of the metal material.

[0124] According to Equation 1, as the dielectric constant of the organic material or the dielectric constant of the metal material increases, the value of the SPP constant (k spp ) increases. As the refractive index of the upper functional layer (e.g., the 2-1 functional layer 223a, the 2-2 functional layer 223b, or the 2-3 functional layer 223c) adjacent to the counter electrode 230 and / or the capping layer 250 increases, the dielectric constant of the upper functional layer and / or the capping layer 250 can increase, and accordingly, the SPP constant value can increase.

[0125] The refractive index of each of the 2-1 functional layer 223a, the 2-2 functional layer 223b, and the 2-3 functional layer 223c can be in the range of, for example, from about 2.0 to about 3.0. The refractive index of each of the 2-1 functional layer 223a, the 2-2 functional layer 223b, and the 2-3 functional layer 223c can be in the range of, for example, from about 2.3 to about 3.0. When the refractive index of each of the 2-1 functional layer 223a, the 2-2 functional layer 223b, and the 2-3 functional layer 223c satisfies the above range, the lifetimes of the first to third light-emitting diodes LED1, LED2, and LED3 can be effectively increased. When the refractive index of each of the 2-1 functional layer 223a, the 2-2 functional layer 223b, and the 2-3 functional layer 223c is less than 2.0, the SPP may be relatively reduced, and accordingly, the lifetimes of the first to third light-emitting diodes LED1, LED2, and LED3 may be reduced.

[0126] The refractive index of the ETL included in each of the 2-1 functional layer 223a, the 2-2 functional layer 223b, and the 2-3 functional layer 223c can be in the range of, for example, from about 2.0 to about 3.0. The refractive index of the ETL included in each of the 2-1 functional layer 223a, the 2-2 functional layer 223b, and the 2-3 functional layer 223c can be in the range of, for example, from about 2.3 to about 3.0.

[0127] The refractive index of the capping layer 250 can be in a range, for example, from about 2.3 to about 3.0. For example, the refractive index of the capping layer 250 can be in a range from about 2.5 to about 3.0. When the refractive index of the capping layer 250 satisfies the above range, the lifetimes of the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3 can be effectively increased. When the refractive index of the capping layer 250 is less than about 2.3, as the SPP relatively decreases, the lifetimes of the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3 may decrease.

[0128] In one or more embodiments, in order to prevent or reduce the decrease in the light extraction efficiency of the display device 1 as the SPP relatively increases, the display device 1 may further include a first optical function layer 260 located on the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3 (see Figure 3 ). Since the first optical function layer 260 includes an uneven surface (or an irregular surface), the light extraction efficiency of the display device 1 can be improved.

[0129] Hereinafter, one or more embodiments corresponding to Figure 5 and one or more embodiments corresponding to Figure 6 are modified embodiments of the embodiments described with reference to Figure 3 and Figure 4 , and thus, redundant descriptions will be omitted and the description will focus on the changed contents.

[0130] Figure 5 is a schematic cross-sectional view of the display device 1 according to one or more embodiments.

[0131] Referring to Figure 5 , the first optical function layer 260 can be located on the counter electrode 230. In one or more embodiments, the first optical function layer 260 can be located below the capping layer 250. In one or more embodiments, the first optical function layer 260 can be between the counter electrode 230 and the capping layer 250.

[0132] Figure 6 is a schematic cross-sectional view of the display device 1 according to one or more embodiments. Figure 7 Schematically shows Figure 6 an enlarged view of the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3 according to one or more embodiments.

[0133] Referring to Figure 6 and Figure 7, the display device 1 may further include a first optical functional layer 260a located on the first to third light-emitting diodes LED1, LED2, and LED3, and a second optical functional layer 260b provided in the first to third light-emitting diodes LED1, LED2, and LED3.

[0134] In one or more embodiments, the first optical functional layer 260a is shown on the encapsulation layer 250, but the present disclosure is not limited thereto. For example, as Figure 5 shown, the first optical functional layer 260a may be located below the encapsulation layer 250 and between the counter electrode 230 and the encapsulation layer 250.

[0135] The first optical functional layer 260a may have an uneven surface (or an irregular surface). In this specification, the fact that the first optical functional layer 260a has an uneven surface (or an irregular surface) may mean that the surface roughness of the first optical functional layer 260a is relatively greater than the surface roughness of the components in contact with or adjacent to the first optical functional layer 260a. For example, the surface roughness of the first optical functional layer 260a may be greater than the surface roughness of the encapsulation layer 250. For example, the surface roughness of the first optical functional layer 260a may be greater than the surface roughness of the counter electrode 230. In one or more embodiments, the first optical functional layer 260a may include an organic material.

[0136] Each of the first to third light-emitting diodes LED1, LED2, and LED3 may include a second optical functional layer 260b between the upper functional layer (e.g., the 2-1 functional layer 223a, the 2-2 functional layer 223b, or the 2-3 functional layer 223c) and the counter electrode 230.

[0137] The second optical functional layer 260b may have an uneven surface or an irregular surface. In this specification, the fact that the second optical functional layer 260b has an uneven surface (or an irregular surface) may mean that the surface roughness of the second optical functional layer 260b is relatively greater than the surface roughness of the components in contact with or adjacent to the second optical functional layer 260b. For example, the surface roughness of the second optical functional layer 260b may be greater than the surface roughness of the 2-1 to 2-3 functional layers 223a, 223b, and 223c. For example, the surface roughness of the second optical functional layer 260b may be greater than the surface roughness of the encapsulation layer 250. For example, the surface roughness of the second optical functional layer 260b may be greater than the surface roughness of the counter electrode 230. In one or more embodiments, the second optical functional layer 260b may include an organic material.

[0138] The first optical functional layer 260a may be located above the counter electrode 230, and the second optical functional layer 260b may be located below the counter electrode 230.

[0139] Since the second optical functional layer 260b is provided in the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3, when the thickness of the second optical functional layer 260b is excessively increased, the light extraction efficiency may decrease. Accordingly, the thickness THb of the second optical functional layer 260b may be formed to be less than the thickness THa of the first optical functional layer 260a. That is, the thickness THa of the first optical functional layer 260a may be greater than the thickness THb of the second optical functional layer 260b. Since the second optical functional layer 260b is formed relatively thin, the first optical functional layer 260a having an uneven surface (or an irregular surface) may be additionally provided on the first light-emitting diode to the third light-emitting diodes LED1, LED2, and LED3 to more effectively improve the light extraction efficiency.

[0140] Figure 8 is a graph showing the results of surface plasmon polariton (SPP) simulations according to the thickness of the counter electrode. The counter electrode includes AgMg.

[0141] Reference Figure 8 , it can be seen that the SPP increases as the thickness of the counter electrode increases. For example, when the counter electrode including AgMg is about or greater, it can be seen that the SPP is about 15% or greater. When the SPP increases, the lifetime of the light-emitting diode can be increased by reducing excessive exciton energy.

[0142] Figure 9 is a graph obtained by measuring the luminance over time in embodiments in which the counter electrode has different thicknesses. For example, Figure 9 shows the luminance over time of embodiments in which the counter electrode includes AgMg and has thicknesses of and respectively.

[0143] Reference Figure 9 , it can be seen that as the thickness of the counter electrode increases, the rate of decrease in luminance over time decreases. In other words, as the thickness of the counter electrode increases, the lifetime of the light-emitting diode increases. In embodiments in which the thickness of the counter electrode is about or greater, the time for the luminance to reach 95% of the initial luminance is about 250 hours or longer, while in embodiments in which the thickness of the counter electrode is less than about , the time for the luminance to reach 95% of the initial luminance is less than about 250 hours. When the thickness of the counter electrode is about When it is [[ID=]] or greater, it can be seen that the lifetime of the light-emitting diode is effectively increased because the rate of decrease in brightness over time is low.

[0144] Figure 10 is a graph obtained by measuring transient electroluminescence (TEL) over time in an embodiment where the counter electrode has different thicknesses. For example, Figure 10 shows an embodiment where the counter electrode includes AgMg and has and thicknesses of transient electroluminescence (TEL) over time.

[0145] Referring to Figure 10 , as the thickness of the counter electrode increases, the slope at the falling edge where the intensity of electroluminescence (EL) decreases over time increases. In other words, as the thickness of the counter electrode increases, light is emitted in a relatively short time of the triplet excited state, and the triplet excited state returns to the ground state, thereby reducing the deterioration of the light-emitting diode. In an embodiment where the thickness of the counter electrode is about or greater, the time for maintaining the triplet state is shorter than that in an embodiment where the thickness of the counter electrode is less than about , thereby reducing the deterioration of the light-emitting diode and increasing the lifetime of the light-emitting diode.

[0146] According to an embodiment of the present disclosure, a light-emitting diode with an effectively extended lifetime and a display device including the light-emitting diode can be realized. Obviously, the scope of the present disclosure is not limited by these effects.

[0147] It should be understood that the embodiments described herein should be considered only in a descriptive sense and not for the purpose of limitation. The description of aspects within each embodiment should generally be considered applicable to other similar aspects in other embodiments. Although one or more embodiments have been described with reference to the accompanying drawings, those of ordinary skill in the art will understand that various changes in form and details can be made therein without departing from the spirit and scope defined by the claims having functional equivalents included therein.

Claims

1. A display device, comprising: a substrate; a pixel electrode, above the substrate; The counter electrode, above the pixel electrode, and having a thickness between and ; an emission layer, between the pixel electrode and the counter electrode; a first functional layer, between the pixel electrode and the emission layer; and A second functional layer, between the emission layer and the counter electrode, and having a thickness between and is provided.

2. The display device according to claim 1, wherein The second functional layer includes an electron transport layer having a thickness between and .

3. The display device according to claim 1, wherein, The second functional layer has a refractive index between 2.0 and 3.

0.

4. The display device according to claim 1, further comprising: a capping layer, above the counter electrode.

5. The display device according to claim 4, wherein, The capping layer has a refractive index between 2.3 and 3.

0.

6. The display device according to claim 1, further comprising: a first optical functional layer, above the counter electrode and having an uneven surface.

7. The display device according to claim 6, further comprising: a second optical functional layer, between the second functional layer and the counter electrode and having an uneven surface.

8. The display device according to claim 7, wherein, The thickness of the first optical functional layer is greater than the thickness of the second optical functional layer.

9. The display device according to claim 1, wherein, The emission layer is configured to emit blue light, and Wherein, the distance between the pixel electrode and the emission layer is between and .

10. The display device according to claim 1, wherein, The emission layer is configured to emit green light, and Among them, the distance between the pixel electrode and the emission layer is between and .

11. The display device according to claim 1, wherein, The emission layer is configured to emit red light, and Among them, the distance between the pixel electrode and the emission layer is between and .

12. The display device according to any one of claims 1 to 11, wherein, The pixel electrode includes a reflective electrode, and wherein, the counter electrode includes a transmissive electrode.

13. A display device, comprising: a substrate; a pixel electrode, above the substrate; The counter electrode, above the pixel electrode, and having a thickness between and ; an emission layer, between the pixel electrode and the counter electrode; a first functional layer, between the pixel electrode and the emission layer; and a second functional layer, between the emission layer and the counter electrode and having a refractive index between 2.0 and 3.

0.

14. The display device according to claim 13, further comprising: a capping layer, above the counter electrode.

15. The display device according to claim 14, wherein, The capping layer has a refractive index between 2.3 and 3.

0.

16. The display device according to any one of claims 13-15, further comprising: a first optical functional layer, above the counter electrode and having an uneven surface.

17. The display device according to claim 16, further comprising: a second optical functional layer, between the second functional layer and the counter electrode and having an uneven surface.

18. The display device according to claim 17, wherein, The thickness of the first optical functional layer is greater than the thickness of the second optical functional layer.

19. A light emitting diode, comprising: a pixel electrode; The counter electrode, above the pixel electrode and having a thickness between and ; an emission layer, between the pixel electrode and the counter electrode; a first functional layer, between the pixel electrode and the emission layer; and The second functional layer, between the emission layer and the counter electrode, and having a thickness between and .

20. The light-emitting diode according to claim 19, wherein, The second functional layer has a refractive index between 2.0 and 3.0.

Images