White light emitting device and light emitting display device including the same

Abstract

The present disclosure provides a white light emitting device and a light emitting display device including the same. The white light emitting device and the light emitting display device including the same have an improved structure which can prevent color difference between regions and eliminate a difference in color characteristics between low and high gray levels.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Korean Patent Application No. 10-2020-0186847, filed on December 29, 2020, which is incorporated herein by reference as if fully set forth herein. Technical Field

[0003] The present invention relates to a display device, and more particularly, to a white light-emitting device and a light-emitting display device including the same, which have an improved structure capable of preventing color differences between regions and eliminating differences in color characteristics between low grayscale and high grayscale. Background Art

[0004] Recently, self-luminous display devices are considered to be competitive applications because they do not require a separate light source and can achieve compact device design and vivid color display. Self-luminous display devices can be classified into organic light-emitting display devices and inorganic light-emitting display devices according to the light-emitting materials therein.

[0005] The self-luminous display apparatus includes a plurality of sub-pixels and a light-emitting device disposed in each sub-pixel, thereby emitting light without a separate light source.

[0006] As a display device, a tandem device—a tandem device that achieves high resolution and high integration and in which an organic layer and a light-emitting layer are generally formed without a fine metal mask—has recently received increasing attention due to its favorable processability, and research thereon is underway. Summary of the Invention

[0007] Light-emitting display devices generally require the ability to efficiently express various colors and are typically formed of a plurality of light-emitting layers in a stacked structure.

[0008] However, there are differences in efficiency between light-emitting layers of different colors. In addition, when multiple light-emitting layers are driven at low and high current densities, the light-emitting layers may emit colors unevenly, which can be considered as color anomaly.

[0009] An object of the present invention is to provide a white light-emitting device and a light-emitting display device including the same, which have an improved structure that can prevent color differences between regions and eliminate differences in color characteristics between low grayscale and high grayscale.

[0010] A white light-emitting device according to an embodiment of the present invention may include: a first electrode and a second electrode disposed opposite each other across a substrate; a first stack disposed between the first electrode and the first charge generation layer, the first stack configured to emit a first light; and a second stack disposed between the first charge generation layer and the second electrode, the second stack including first to third light-emitting layers stacked in sequence. The first to third light-emitting layers may emit light such that the wavelength of the light gradually decreases in a direction away from the first stack, and the thicknesses of the first to third light-emitting layers may gradually decrease in the order of the second light-emitting layer, the first light-emitting layer, and the third light-emitting layer.

[0011] According to an embodiment of the present invention, a light-emitting display device may include: a substrate including a plurality of sub-pixels; a first electrode disposed in each of the plurality of sub-pixels on the substrate; a second electrode disposed opposite the first electrode across the plurality of sub-pixels; a first stack disposed between the first electrode and a first charge generation layer across the plurality of sub-pixels, the first stack configured to emit first light; and a second stack disposed between the first charge generation layer and the second electrode across the plurality of sub-pixels, the second stack including first to third light-emitting layers stacked in sequence. The first to third light-emitting layers may emit light such that the wavelength of the light gradually decreases in a direction away from the first stack, and the thicknesses of the first to third light-emitting layers may gradually decrease in the order of the second light-emitting layer, the first light-emitting layer, and the third light-emitting layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate one or more embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings:

[0013] Figure 1 is a cross-sectional view showing a white light emitting device according to a first embodiment of the present invention;

[0014] Figure 2 is a cross-sectional view showing a white light emitting device according to a second embodiment of the present invention;

[0015] Figure 3 is a diagram showing a second stack of a white light emitting device of the present invention;

[0016] Figures 4A to 4D is a graph showing the relationship between current density and CIEy color coordinates in the first to fourth experimental examples;

[0017] Figure 5A and Figure 5B is a graph showing the relationship between current density and CIEy color coordinates in the fourth experimental example and the fifth experimental example;

[0018] Figure 6 is a plan view showing a light emitting display device of the present invention;

[0019] Figure 7 The third light emitting layer is shown along Figure 6 A graph showing the thickness variation of line II' in FIG.

[0020] Figure 8 is a cross-sectional view showing a light emitting display device according to the present invention connected to a lower driving unit; and

[0021] Figure 9 is a circuit diagram of a sub-pixel of an example of a light-emitting display device according to the present invention. DETAILED DESCRIPTION

[0022] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Where possible, the same reference numerals will be used throughout the accompanying drawings to refer to identical or similar components. In the following description of the present invention, when a detailed description of known functions and configurations incorporated herein may obscure the subject matter of the present invention, such detailed description will be omitted. In addition, in the following description of the present invention, the names of the elements are selected for ease of explanation, and these names may be different from the actual names.

[0023] In the accompanying drawings for illustrating exemplary embodiments of the present invention, for example, the shapes, sizes, ratios, angles and numbers shown are given by way of example and are therefore not limited to the disclosure of the present invention. Throughout the specification, the same reference numerals refer to the same constituent elements. In addition, in the following description of the present invention, when a detailed description of the known functions and configurations incorporated herein may make the subject matter of the present invention quite unclear, the detailed description will be omitted. Unless used together with the term "only", the terms "include", "comprise" and / or "have" used in this specification do not exclude the presence or addition of other elements. Unless the context clearly indicates otherwise, the singular form is intended to also include the plural form.

[0024] In the interpretation of constituent elements included in various embodiments of the present invention, the constituent elements are interpreted as including an error range even if there is no explicit description thereof.

[0025] In the description of various embodiments of the present invention, when describing a positional relationship, for example, when using "on...", "above...", "below...", "next to...", etc. to describe the positional relationship between two components, unless the terms "directly" or "closely" are used, one or more other components may be located between the two components.

[0026] In the description of various embodiments of the present invention, when describing a temporal relationship, for example, when using "after", "subsequently", "next", "before", etc. to describe the temporal relationship between two actions, unless used with the term "immediately" or "immediately afterwards", these actions may not occur continuously.

[0027] In the description of various embodiments of the present invention, although terms such as "first" and "second" may be used to describe various elements, these terms are only used to distinguish the same or similar elements from each other. Therefore, in this specification, unless otherwise mentioned, the element indicated by "first" may be the same as the element indicated by "second" without exceeding the technical scope of the present invention.

[0028] The various features of the various embodiments of the present invention can be partially or completely coupled and combined with each other, and various technical connections and operation modes thereof are possible. These various embodiments can be performed independently of each other, or can be performed in association with each other.

[0029] In this specification, the term "doping" means adding a material of any layer having physical properties different from the material accounting for the maximum weight percentage of the corresponding layer (for example, N-type and P-type, or organic material and inorganic material) to the material accounting for the maximum weight percentage in an amount corresponding to a weight percentage of 30 vol% or less. In other words, a "doped" layer means a layer in which the main material and the dopant material of any layer are distinguishable from each other considering their weight percentages. In addition, the term "undoped" refers to all cases except for the case corresponding to the term "doping". For example, when any layer is formed of a single material or a mixture of materials having the same or similar properties, the layer is considered to be an "undoped" layer. In another example, when at least one material among the constituent materials of any layer is P-type and all other constituent materials of the layer are not N-type, the layer is considered to be an "undoped" layer. In another example, when at least one material among the constituent materials of any layer is an organic material and all other constituent materials of the layer are not inorganic materials, the layer is considered to be an "undoped" layer. In another example, when all constituent materials of any layer are organic materials, at least one of the constituent materials is N-type, at least another constituent material is P-type, and the weight percentage of the N-type material is 30 vol% or less or the weight percentage of the P-type material is 30 vol% or less, the layer is considered to be a "doped" layer.

[0030] In this specification, an electroluminescence (EL) spectrum is calculated by multiplying (1) a photoluminescence (PL) spectrum, which applies inherent characteristics of a light-emitting material such as a dopant material or a host material included in an organic light-emitting layer, by (2) an output coupling or emittance spectrum curve, which is determined by the structure and optical characteristics of an organic light-emitting element including the thickness of an organic layer such as an electron transport layer.

[0031] Figure 1 is a cross-sectional view showing a white light emitting device according to a first embodiment of the present invention.

[0032] like Figure 1 As shown in , the white light-emitting device according to the first embodiment of the present invention includes a first electrode 110 and a second electrode 200 arranged opposite to each other across a substrate 100, and also includes a charge generation layer 150 arranged between the first electrode 110 and the second electrode 200, a first stack S1 arranged between the first electrode 110 and the charge generation layer 150, and a second stack S2 arranged between the second electrode 200 and the charge generation layer 150.

[0033] The first stack S1 is located on the first electrode 110 and includes a first hole transport-related common layer 1210 , a blue light emitting layer 130 , and a first electron transport-related common layer 1220 .

[0034] The second stack S2 includes: a second hole transport-related common layer 1230; first to third light-emitting layers 141, 142 and 143, which are stacked sequentially and emit light with a wavelength gradually shortened from the first light-emitting layer 141 to the third light-emitting layer 143; and a second electron transport-related common layer 1240.

[0035] Each of the first hole transport related common layer 1210 and the second hole transport related common layer 1230 is a layer related to hole injection and hole transport, and may include at least one of the hole transport layer HTL1, HTL2 or HTL3 or the electron blocking layer. In addition, the first hole transport related common layer 1210 may further include a hole injection layer HIL (121) that contacts the first electrode 110 and reduces the interface resistance when holes are injected from the first electrode 110. Each of the first hole transport related common layer 1210 and the second hole transport related common layer 1230 may be formed as a single layer or may be formed as multiple layers. As shown in the figure, the hole transport related common layer included in one stack in the stack may be formed as multiple layers, while the hole transport related common layer included in another stack in the stack may be formed as a single layer. For example, as Figure 1As shown in , when the first hole transport-related common layer 1210 of the first stack S1 is formed into multiple layers, the hole transport layer HTL2 close to the light emitting layer 130 can serve as an electron blocking layer to prevent electrons or excitons from escaping from the light emitting layer 130 to the hole transport layer 122.

[0036] Each of the first electron transport-related common layer 1220 and the second electron transport-related common layer 1240 is a layer related to electron transport and the rate of supplying electrons to the adjacent light-emitting layer, and may include at least one of an electron transport layer ETL1 or ETL2 or a hole blocking layer. In addition, the second electron transport-related common layer 1240 may further include an electron injection layer that contacts the second electrode 200 and reduces the interface resistance when electrons are injected from the second electrode 200. Each of the first electron transport-related common layer 1220 and the second electron transport-related common layer 1240 may be formed as a single layer or may be formed as a plurality of layers.

[0037] In the white light emitting device according to the first embodiment of the present invention, the first stack S1 includes a single blue light emitting layer 130 emitting blue light. The blue light may have an emission peak within a range of 430 nm to 490 nm.

[0038] Unlike the first stack S1, the second stack S2 includes a phosphorescent light-emitting unit 140, which is configured so that the first to third light-emitting layers 141, 142, and 143 are in contact with each other and emit different light with wavelengths longer than the wavelength of blue light. Specifically, the first to third light-emitting layers 141, 142, and 143 emit red light, yellow-green light, and green light, respectively. That is, the first light-emitting layer 141 emits light with an emission peak in the range of 590nm to 650nm, the second light-emitting layer 142 emits light with an emission peak in the range of 540nm to 590nm, and the third light-emitting layer 143 emits light with an emission peak in the range of 510nm to 560nm. Among the first to third light-emitting layers 141, 142, and 143 of the second stack S2, the third light-emitting layer 143 emits light with the shortest wavelength. However, the light from the third light-emitting layer 143 has a longer wavelength than the light from the blue light-emitting layer 130.

[0039] The reason for providing the first to third light-emitting layers 141, 142, and 143, which emit light of different wavelengths, in the second stack S2 is to enable the light-emitting display device to achieve a rich color representation. As long as each of the light-emitting layers for emitting light of various colors does not impair the luminescent properties of the other light-emitting layers, the color representation effect can be improved as the number of light-emitting layers increases, and the color representation range that can be achieved by the light-emitting display device can be increased. This means that a large range of color representations that can be achieved by the light-emitting display device falls within the range according to the DCI standard or the BT2020 standard.

[0040] The light-emitting layer of the second stack S2 that emits light of a long wavelength can be implemented as a high-efficiency phosphorescent light-emitting layer. Because the threshold driving voltage gradually decreases in the order of the third light-emitting layer 143, the second light-emitting layer 142 and the first light-emitting layer 141, there is no energy for excitation in the upper light-emitting layer in the second stack S2 that can be used in the lower light-emitting layer. Therefore, the efficiency of the second stack S2 can be improved. To this end, the first to third light-emitting layers 141, 142 and 143 are formed so that the wavelength of light emitted therefrom gradually increases in the order of the third light-emitting layer 143, the second light-emitting layer 142 and the first light-emitting layer 141, so that the threshold driving voltage gradually decreases in this order. Figure 1 In the illustrated embodiment, the first light-emitting layer 141 is a red light-emitting layer, the second light-emitting layer 142 is a yellow-green light-emitting layer, and the third light-emitting layer 143 is a green light-emitting layer.

[0041] In the white light-emitting device of the present invention, in which multiple light-emitting layers are arranged adjacent to each other, there is a difference in thickness between the light-emitting layers 141, 142, and 143 in the second stack S2. Among the light-emitting layers in the second stack S2, the second light-emitting layer 142 has the greatest thickness, and the third light-emitting layer 143 has the smallest thickness. That is, the thickness of the phosphorescent light-emitting units 140 that emit phosphorescent light has the following relationship: thickness of second light-emitting layer 142 > thickness of first light-emitting layer 141 > thickness of third light-emitting layer 143. Here, since the second light-emitting layer 142, which exhibits white light, occupies the largest portion, it can be the thickest layer in the second stack S2, and the first and third light-emitting layers 141, 143 can be thinner than the second light-emitting layer 142. The reason why the third light-emitting layer 143 is thinner than the first light-emitting layer 141 is to minimize or prevent color anomalies in the edge regions of the substrate 100 that may occur at low current densities by thinning the third light-emitting layer 143, which is formed relatively late in the deposition process and is therefore sensitive to thermal stress.

[0042] In the white light-emitting device of the present invention, the organic stack OS including the first stack S1, the charge generation layer 150 and the second stack S2 provided on the first electrode 110, and the second electrode 200 are layers continuously formed in the display area of ​​the substrate 100 without any breaks. That is, when a plurality of sub-pixels are provided on the substrate 100, the first electrode 110 is divided for each sub-pixel, but each component provided on the first electrode 110 is formed as a unitary body at least in the display area without using a fine metal mask. Therefore, in the white light-emitting device of the present invention, after forming the first electrode 110, the use of a fine metal mask can be omitted, thereby improving processing performance and reducing yield reduction that may be caused by misalignment of the mask. In addition, in the white light-emitting device of the present invention, light of different colors emitted from the plurality of stacks S1 and S2 can be combined to generate white light, and the sub-pixels can be directed to the color filters 109R, 109G and 109B (refer to Figure 8 ) emits light of different colors. Each layer of the organic stack OS of the white light emitting device of the present invention can be formed using an open mask that completely opens the display area of ​​the substrate 100.

[0043] Each layer of the first stack S1, the charge generation layer 150, the layers of the second stack S2, and the second electrode 200 are formed as a whole in the display area by supplying a vaporized material from a source to the deposition chamber. In this case, during the deposition of each layer, a difference in thermal gradient may occur between the center region and the edge region of the display area of ​​the substrate 100, and an entropy difference may occur between portions of the deposition surface of each layer.

[0044] Furthermore, the organic materials are deposited on the various layers at different temperatures. In particular, the light-emitting layers of the second stack are continuously formed, and heat is continuously applied to the substrate 100 as the light-emitting layers are stacked upward. Therefore, during the deposition of the third light-emitting layer 143, which is the last deposited layer of the light-emitting layer, the thermal gradient difference between the various regions of the substrate 100 may increase, thereby resulting in a greater thickness difference between the central region and the edge region of the third light-emitting layer. Figure 1 In the illustrated embodiment, the total thickness of the third light emitting layer 143 of the second stack S2 is reduced, whereby the third light emitting layer 143 is less affected by the difference in thermal gradient between regions of the substrate 100 .

[0045] Hereinafter, the thickness relationship between the respective light emitting layers in the phosphorescent light emitting unit 140 and the resulting effects will be described in detail.

[0046] Each of the blue light emitting layer 130 and the first to third light emitting layers 141, 142, and 143 includes a host and a dopant. One or more hosts may be provided in each light emitting layer as needed.

[0047] The blue light-emitting layer 130 includes a fluorescent dopant, while each of the first to third light-emitting layers 141, 142, and 143 includes a phosphorescent dopant, which has a relatively high efficiency. The phosphorescent dopant of each of the first to third light-emitting layers 141, 142, and 143 is a metal complex including one of iridium (Ir), platinum (Pt), osmium (Os), gold (Au), titanium (Ti), zirconium (Zr), hafnium (Hf), europium (Eu), terbium (Tb), palladium (Pd), and thulium (Tm). The host of each of the first to third light-emitting layers 141, 142, and 143 may include a host having electron transport capability and / or a host having hole transport capability. The phosphorescent dopants of the first to third light-emitting layers 141, 142, and 143 have a difference in triplet energy level T1 required for excitation.

[0048] As shown, charge generation layer 150 positioned between stacks S1 and S2 may include n-type charge generation layer 151 and p-type charge generation layer 153. Alternatively, charge generation layer 150 may be formed as a single layer in which n-type dopants and p-type dopants are contained in a single body.

[0049] The first electrode 110 may function as an anode, and the second electrode 200 may function as a cathode. The first electrode 110 may include a transparent electrode, and the second electrode 200 may include a reflective electrode.

[0050] Figure 2 is a cross-sectional view showing a white light emitting device according to a second embodiment of the present invention.

[0051] like Figure 2 As shown in FIG, the white light-emitting device according to the second embodiment of the present invention includes: a phosphorescent stack PS including first to third light-emitting layers 141, 142, and 143; a first blue light-emitting stack BS1 located below the phosphorescent stack PS and emitting blue light; and a second blue light-emitting stack BS2 located above the phosphorescent stack PS and emitting blue light. That is, the white light-emitting device according to the second embodiment differs from the first embodiment in that a plurality of blue light-emitting stacks are provided to improve the efficiency of blue light emission, which is insufficient compared to the phosphorescent stack PS.

[0052] In addition, the charge generation layer 150 is provided between the first blue light-emitting stack BS1 and the phosphorescent stack PS, and the charge generation layer 170 is provided between the second blue light-emitting stack BS2 and the phosphorescent stack PS. As shown in the figure, the charge generation layer 150 may include an n-type charge generation layer 151 and a p-type charge generation layer 153 stacked on the n-type charge generation layer 151, and the charge generation layer 170 may include an n-type charge generation layer 171 and a p-type charge generation layer 173 stacked on the n-type charge generation layer 171. Alternatively, each of the charge generation layers 150 and 170 may be formed as a single layer in which an n-type dopant and a p-type dopant are contained in a single body.

[0053] Although Figure 2 , a single sub-pixel is shown in FIG, but the first electrode 110 may be patterned corresponding to a plurality of sub-pixels so as to be divided for each sub-pixel. The organic stacked layer OS and the second electrode 200 located on the first electrode 110 may be continuously formed across the plurality of sub-pixels without a break therein.

[0054] In the white light-emitting device according to the second embodiment of the present invention, the first electrode 110 is divided for each sub-pixel, but each component provided on the first electrode 110 is formed as a whole at least in the display area without using a fine metal mask. Therefore, in the white light-emitting device according to the second embodiment of the present invention, the use of a fine metal mask can be omitted after forming the first electrode 110, thereby improving processing performance and reducing yield reduction that may be caused by misalignment of the mask. In addition, in the white light-emitting device according to the second embodiment of the present invention, light of different colors emitted from a plurality of stacks S1 and S2 (or a blue stack (BS1 and BS2) and a phosphor stack (PS)) can be combined to generate white light, and the sub-pixels can be directed to the color filters 109R, 109G, and 109B (refer to Figure 8 ) emit light of different colors.

[0055] The first blue light emitting stack BS1 is located on the first electrode 110 and includes a first hole transport-related common layer 1210 , a first blue light emitting layer BEML1 ( 130 ), and a first electron transport-related common layer 124 .

[0056] The second stack S2 (phosphorescent stack) includes: a second hole transport-related common layer 125; first to third light-emitting layers 141, 142 and 143, which are stacked sequentially and emit light with a wavelength gradually shortened from the first light-emitting layer 141 to the third light-emitting layer 143; and a second electron transport-related common layer 126.

[0057] The second blue light emitting stack BS2 includes a third hole transport related common layer 1250 , a second blue light emitting layer BEML2 ( 160 ) and a third electron transport related common layer 129 .

[0058] Similar to the first blue light emitting stack BS1, the third hole transport-related common layer 1250 may include a plurality of hole transport layers 127 and 128. The hole transport layer HTL5 (128) located on the hole transport layer HTL4 (127) may function as an electron blocking layer.

[0059] The first electrode 110 may include a transparent electrode, and the second electrode 200 may include a reflective electrode, so that light generated by the organic stack OS may be emitted through the first electrode 110 .

[0060] The second electrode 200 may be formed such that multiple layers are stacked one on top of the other. Among the multiple layers, the layer in contact with the organic stacked layer OS may be formed of an inorganic compound including a metal and a halogen material such as fluorine, and may function as an electron injection layer. When the electron injection layer is formed of an inorganic material or an inorganic compound, the electron injection layer may be formed in a chamber different from the organic stacked layer OS and may be formed using the same mask and / or in the same chamber as the second electrode 200.

[0061] As described above, each of the first and second embodiments includes a phosphorescent stack S2 or PS in which a plurality of phosphorescent light emitting layers are sequentially stacked, including the phosphorescent light emitting unit 140. The light emitting principle of the phosphorescent stack PS will now be briefly described.

[0062] Figure 3 1 is a diagram showing the second stack of the white light emitting device of the present invention.

[0063] like Figure 3 As shown in FIG, holes are supplied from the second hole transport-related common layer 125 in the second stack S2 to the phosphorescent light emitting unit 140, and electrons are supplied from the second electron transport-related common layer 126 in the second stack S2 to the phosphorescent light emitting unit 140. Excitons are generated by the recombination of holes and electrons in each of the first to third light emitting layers 141, 142, and 143, and light emission occurs when the energy of the excitons drops to the ground state.

[0064] The first to third light-emitting layers 141, 142, and 143 are provided between the second hole transport-related common layer 125 and the second electron transport-related common layer 126, and emit light having a wavelength gradually shortening in a direction approaching the second electron transport-related common layer 126. The thicknesses of the first to third light-emitting layers 141, 142, and 143 gradually decrease in the order of the second light-emitting layer 142, the first light-emitting layer 141, and the third light-emitting layer 143.

[0065] Among the light-emitting layers of the second stack S2, the second light-emitting layer 142 has the largest thickness, while the third light-emitting layer 143 has the smallest thickness. That is, the phosphorescent light-emitting unit 140 that emits phosphorescence has the following thickness relationship: the thickness of the second light-emitting layer 142 > the thickness of the first light-emitting layer 141 > the thickness of the third light-emitting layer 143. Here, since the second light-emitting layer 142, which exhibits white color, occupies the largest portion, the second light-emitting layer 142 can be the thickest layer in the second stack S2, and the first light-emitting layer 141 and the third light-emitting layer 143 can be thinner than the second light-emitting layer 142. The reason why the third light-emitting layer 143 is thinner than the first light-emitting layer 141 is to minimize or prevent the occurrence of color abnormalities in the edge area of ​​the substrate 100 that may occur at low current density by thinning the third light-emitting layer 143, which is formed relatively late in the deposition process and is therefore sensitive to thermal stress.

[0066] The total thickness of the phosphorescent light emitting unit 140 including the first to third light emitting layers 141, 142, and 143 may be to Because three light-emitting layers are provided in phosphorescent light-emitting unit 140, the first to third light-emitting layers 141, 142, and 143 are formed to have appropriate thicknesses, taking into account the overall thickness of phosphorescent light-emitting unit 140. The light-emitting layers of phosphorescent light-emitting unit 140 are formed from highly efficient phosphorescent light-emitting materials and are arranged so that the wavelength of light emitted therefrom gradually increases in the order of third light-emitting layer 143, second light-emitting layer 142, and first light-emitting layer 141. Here, first light-emitting layer 141 emits red light, second light-emitting layer 142 emits yellow-green light, and third light-emitting layer 143 emits green light.

[0067] The third light emitting layer 143 may be the thinnest layer in the phosphorescent light emitting unit 140, and the thickness of the third light emitting layer 143 may be 20% to 30% of the total thickness of the phosphorescent light emitting unit 140. The thickness of the third light emitting layer 143 may be less than that of the first or second light emitting layer.

[0068] In the white light-emitting device of the present invention, the reason why the third light-emitting layer 143 has the minimum thickness is that the change in the color coordinates of the third light-emitting layer 143 emitting green light due to the change in current density is greater than the change in the color coordinates of the first light-emitting layer 141 emitting red light or the change in the color coordinates of the second light-emitting layer 142 emitting yellow-green light.

[0069] Hereinafter, the change of the color coordinates of the experimental example due to the change of the current density will be described. In particular, the color coordinates change greatly at low current density. Hereinafter, the change of the color coordinates at the current density from 0.25 mA / cm 2 to 10mA / cm 2Observation results of the change of color coordinates in the low current density range.

[0070] Figures 4A to 4D Graphs showing the relationship between current density and CIEy color coordinates in the first to fourth experimental examples.

[0071] [Table 1]

[0072]

[0073] Each of the first to fourth experimental examples Ex1, Ex2, Ex3, and Ex4 has Figure 2 . However, the first to fourth experimental examples Ex1, Ex2, Ex3, and Ex4 have different thickness ratios of the first to third light-emitting layers 141, 142, and 143. Specifically, in each of the first to fourth experimental examples Ex1, Ex2, Ex3, and Ex4, the second light-emitting layer 142 has the largest thickness, and the thickness of the first light-emitting layer 141 is 0.75 times the thickness of the second light-emitting layer 142. In the first experimental example Ex1, the thickness of the third light-emitting layer 143 is the same as the thickness of the second light-emitting layer 142. In the second experimental example Ex2, the thickness of the third light-emitting layer 143 is 0.55 times the thickness of the second light-emitting layer 142. In the third experimental example Ex3, the thickness of the third light-emitting layer 143 is 0.5 times the thickness of the second light-emitting layer 142. In the fourth experimental example Ex4, the thickness of the third light-emitting layer 143 is 0.45 times the thickness of the second light-emitting layer 142. Under the conditions of the above-mentioned thickness ratios of the first to third light-emitting layers 141, 142, and 143, white color was achieved at a low current density, and the change ΔCIEx of the CIEx color coordinate, the change ΔCIEy of the CIEy color coordinate, and the edge grayscale value were measured to determine whether the color was abnormal or normal. In each of the first to fourth experimental examples Ex1, Ex2, Ex3, and Ex4, the change ΔCIEx of the CIEx color coordinate was small, specifically, 0.020 or less, and the change ΔCIEy of the CIEy color coordinate was greater than the change ΔCIEx of the CIEx color coordinate. In particular, as Figure 4A and Figure 4B As shown in FIG, in each of the first experimental example Ex1 and the second experimental example Ex2, at a high current density (greater than 10 mA / cm 2 ) and the change of CIEy color coordinates ΔCIEy at low current density (0.25 mA / cm 2 Up to 10mA / cm 2), and when driving at a low current density where the CIEy color coordinate change is large, green is expressed more strongly than when achieving white at a high current density. However, it can be seen that the change ΔCIEy in the CIEy color coordinate in the second experimental example Ex2 is smaller than the change ΔCIEy in the CIEy color coordinate in the first experimental example Ex1 when driving at both low and high current densities.

[0074] In addition, it can be seen from Table 1 that as the thickness of the third light-emitting layer 143 decreases from the first experimental example Ex1 to the fourth experimental example Ex4, the change ΔCIEy of the CIEy color coordinate at low current density also decreases, and the degree of change of the CIEy color coordinate at low current density and the degree of change of the CIEy color coordinate at high current density become more similar to each other.

[0075] The edge grayscale values ​​shown in Table 1 are determined using 32 grayscale levels. The larger the edge grayscale value, the greater the deviation from the normal range. Furthermore, color abnormality or normality is determined based on the change in the CIEy color coordinate, ΔCIEy, and the edge grayscale value. The edge grayscale value indicates the difference in color characteristics between the edge and center areas of the display area of ​​the substrate when driven at low current density.

[0076] As can be seen from Table 1, when driven at a low current density, color abnormality occurs in the first experimental example Ex1 and the second experimental example Ex2, whereas the color abnormality is eliminated in the third experimental example Ex3 and the fourth experimental example Ex4.

[0077] In addition, it can be seen that the change ΔCIEy of the CIEy color coordinate gradually decreases from the first experimental example Ex1 to the fourth experimental example Ex4. Therefore, it can be expected that when the thickness of the third light-emitting layer 143 is greater than or equal to 45% of the thickness of the second light-emitting layer 142 and less than 55% of the thickness of the second light-emitting layer 142, the present invention has the following characteristics: Figure 3 The white light emitting device of the phosphorescent light emitting unit 140 configured as shown in FIG. 1 exhibits improved effects.

[0078] Hereinafter, the observation results of the color expression and color coordinate changes due to the change in current density when driving at low current density under the condition that the thickness of the first light-emitting layer is changed and the thickness relationship between the second light-emitting layer and the third light-emitting layer is fixed will be described.

[0079] Figure 5A and Figure 5B : is a graph showing the relationship between the current density and the CIEy color coordinates in the fourth experimental example and the fifth experimental example.

[0080] [Table 2]

[0081]

[0082] As shown in Table 2, the thickness of the third light emitting layer was fixed to 0.45 times the thickness of the second light emitting layer. 2 Up to 10mA / cm 2 ) was measured to be 0.037, and the grayscale level at the edge area of ​​the display area of ​​the substrate was measured to be 1. In the fifth experimental example Ex5, at a low current density (0.25 mA / cm 2 Up to 10mA / cm 2 ) was measured to be 0.039, and the grayscale level at the edge of the display area of ​​the substrate was measured to be 1. Furthermore, no color anomalies occurred in the fourth experimental example Ex4 and the fifth experimental example Ex5. That is, it is expected that when the thickness of the first light-emitting layer is within a range of 0.65 to 0.75 times the thickness of the second light-emitting layer, no color anomalies occur when driven at a low current density.

[0083] From the above experimental results, it can be seen that the thickness of the first light-emitting layer 141 is preferably in the range of 29.5% (0.65 / (0.65+1+0.55)) to 34.1% (0.75 / (0.75+1+0.45)) of the total thickness of the first to third light-emitting layers.

[0084] Meanwhile, the thickness of the third light emitting layer 143 is set to be 20% to 30% of the total thickness of the first to third light emitting layers.The reason why the thickness range of the third light emitting layer 143 is relatively large is as follows.

[0085] Figure 6 is a plan view showing a light emitting display device of the present invention, and Figure 7 The third light emitting layer is shown along Figure 6 Graph showing thickness variation of line II' in FIG.

[0086] like Figure 6 As shown in , the light-emitting display device of the present invention may include a substrate 100, and the substrate 100 may include a display area AA and a non-display area NA, the display area AA having a plurality of sub-pixels SP, the non-display area NA being formed around the display area AA, and a pad unit PAD, a link line connecting a line of the display area AA to the pad unit PAD, a ground line, and a power voltage line are provided in the non-display area NA.

[0087] In the light-emitting display device of the present invention, Figure 1 andFigure 2 The layers of the organic stack OS and the second electrode 200 shown in FIG. 1 occupy the entire area of ​​the display area AA and extend from the display area AA to a portion of the non-display area NA.

[0088] In the light-emitting display device of the present invention, each layer of the organic stack OS may be formed using an opening mask (not shown) that completely opens the display region of the substrate 100 .

[0089] The phosphorescent light-emitting units 140 (141, 142, and 143) of the second stack S2 or PS in the organic stack OS occupy the entire display area AA and extend to a portion of the non-display area NA. This is because, in consideration of the margin required for alignment of the opening mask, the opening mask (not shown) has an opening region (corresponding to the shape of 140) therein while further ensuring margins in all directions so as to completely cover the display area AA.

[0090] However, when the substrate 100 is in the deposition chamber, the center and edge regions of the substrate 100 have different thermal gradient characteristics depending on the location of the heat source. The temperature at the edge region is lower than that at the center region, and therefore, an entropy difference occurs between the various portions of the deposition surface of the substrate 100. Generally, portions with relatively low entropy are in a relatively stable state, and a large thickness of organic material is deposited on these portions. The edge region has lower entropy than the center region, and therefore, a thicker organic layer can be deposited on the edge region than on the center region.

[0091] In particular, when the third light emitting layer 143, which is the last deposited layer of the phosphorescent light emitting layer performing an optical function in the second stack, is formed, the thermal differences between the regions established during the formation of the previous organic layers are strengthened. Figure 7 As shown in FIG, the third light-emitting layer has a thickness difference between the edge region and the center region of display area AA. Specifically, the third light-emitting layer is deposited at the edge region with a greater thickness than at the center region. Because there is an entropy difference between regions of the deposition surface and the third light-emitting layer is deposited at a relatively greater thickness at the edge region, for example, if the phosphorescent light-emitting layers are formed to have the same thickness, the thickness difference between the center region and the edge region of the third light-emitting layer increases, resulting in different color shift characteristics at the edge region and the center region.

[0092] That is, the light-emitting display device of the present invention eliminates abnormal color inversion in the first to third light-emitting layers of the phosphorescent light-emitting unit 140 when driven at a low current density. In addition, because the third light-emitting layer is the last deposited layer of the phosphorescent light-emitting unit, considering the fact that the third light-emitting layer has a thickness difference between its edge region and the central region, the thickness of the third light-emitting layer is reduced in the total thickness of the phosphorescent light-emitting unit to minimize the influence of the thickness difference of the third light-emitting layer.

[0093] In this case, refer to Figure 7 , a difference between a thickness of the third light emitting layer in the edge region of the display region and a thickness of the third light emitting layer in the center region of the display region is 8.3% or less of the thickness of the third light emitting layer in the edge region of the display region.

[0094] Meanwhile, although the third light emitting layer 143 is also formed on a portion of the non-display area NA, the thickness of the third light emitting layer 143 stacked on the non-display area NA does not affect display.

[0095] The light-emitting display device of the present invention can eliminate color abnormality in the edge region simply by forming the first to third light-emitting layers to have respective different thicknesses without changing the number of masks or the shapes of the masks during deposition.

[0096] Hereinafter, the light emitting display apparatus of the present invention will be described in conjunction with the configuration of the above-mentioned white light emitting device, thin film transistor, and color filter.

[0097] Figure 8 is a cross-sectional view showing a light emitting display device according to the present invention, and Figure 9 is a circuit diagram of a sub-pixel of an example of a light-emitting display device according to the present invention.

[0098] like Figure 8 As shown in FIG, the light emitting display device 1000 of the present invention includes a first electrode 110 and a second electrode 120 (in Figure 1 The organic stack OS includes at least one blue light emitting stack S1 or BS1 / BS2 and a phosphorescent light emitting stack S2 or PS (refer to FIG. Figure 1 or Figure 2). The charge generation layer is arranged between the blue light-emitting stack and the phosphorescent light-emitting stack. In addition, the hole transport-related common layer and the electron transport-related common layer are respectively arranged below and above the blue light-emitting layer BEML or BEML1 / BEML2 of the blue light-emitting stack S1 or BS1 / BS2. The phosphorescent light-emitting stack includes a phosphorescent light-emitting unit 140. The phosphorescent light-emitting unit 140 includes first to third light-emitting layers 141, 142 and 143, which emit light with a wavelength gradually shortening from the first light-emitting layer 141 to the third light-emitting layer 143. The hole transport-related common layer and the electron transport-related common layer are respectively arranged below and above the phosphorescent light-emitting unit 140.

[0099] Each sub-pixel emits white light through the organic stack OS2 disposed between the first electrode 110 and the second electrode 120. Color filters 109R, 109G, and 109B are disposed at light emitting sides of the respective sub-pixels so as to emit light of different colors.

[0100] In the illustrated example, the thin film transistor array is provided at the light emitting side. Light from the first electrode 110 passes through the substrate 100 via the color filters 109R, 109G, and 109B.

[0101] The display device of the present invention may include: a substrate 100 having a plurality of sub-pixels R_SP, G_SP, B_SP and W_SP; a white light emitting device OLED (refer to Figure 1 and Figure 2 ), which are typically arranged in the sub-pixels R_SP, G_SP, B_SP and W_SP of the substrate 100; a thin film transistor TFT, which is arranged in each sub-pixel and connected to the first electrode 110 of the white light-emitting device OLED; and color filters 109R, 109G and 109B, which are arranged under the first electrode 110 of at least one sub-pixel.

[0102] Although the display device is shown as including a white sub-pixel W_SP, embodiments are not limited thereto. The white sub-pixel W_SP may be omitted, and may include only a red sub-pixel R_SP, a green sub-pixel G_SP, and a blue sub-pixel B_SP. In some cases, the red sub-pixel, the green sub-pixel, and the blue sub-pixel may be replaced by a cyan sub-pixel, a magenta sub-pixel, and a yellow sub-pixel that can be combined to represent white.

[0103] The thin film transistor TFT includes, for example, a gate electrode 102 , a semiconductor layer 104 , a source electrode 106 a connected to one side of the semiconductor layer 104 , and a drain electrode 106 b connected to the opposite side of the semiconductor layer 104 .

[0104] The gate insulating film 103 is provided between the gate electrode 102 and the semiconductor layer 104 .

[0105] The semiconductor layer 104 can be formed of a material selected from amorphous silicon, polysilicon, an oxide semiconductor, and a combination thereof. For example, when the semiconductor layer 104 is formed of an oxide semiconductor, a channel protective layer 105 can be further provided to be in direct contact with an upper surface of the semiconductor layer 104, thereby preventing damage to a channel portion of the semiconductor layer 104.

[0106] Further, the drain electrode 106b of the thin film transistor TFT can be connected to the first electrode 110 in a region of a contact hole CT formed in the first protective film 107 and the second protective film 108.

[0107] The first protective film 107 is provided to mainly protect the thin film transistor TFT. The color filters 109R, 109G, and 109B can be provided on the first protective film 107.

[0108] When the plurality of sub-pixels SP include a red sub-pixel R SP, a green sub-pixel G SP, a blue sub-pixel B SP, and a white sub-pixel W SP, each of the first to third color filters 109R, 109G, and 109B is provided in the corresponding sub-pixel except for the white sub-pixel W SP so as to transmit white light that has passed through the first electrode 110 for each wavelength. The second protective film 108 is formed under the first electrode 110 so as to cover the first to third color filters 109R, 109G, and 109B. The first electrode 110 is formed on a surface of the second protective film 108 except for the contact hole CT.

[0109] Here, the white light emitting device OLED includes an organic stack OS between the transparent first electrode 110 and a second electrode 120 provided opposite to the first electrode 110 and being reflective, and emits light through the first electrode 110.

[0110] Here, the reference numeral 119 denotes a bank, and "BH" between the banks denotes a bank hole. Light emission is performed in a region opened by the bank hole. The bank hole defines a light emitting portion of each sub-pixel.

[0111] Figure 8 The display device shown in FIG. 1 is a bottom emission type display device. However, the present application is not limited to the bottom emission type display device. By changing the structure shown in FIG. 1 so that the color filter is located on the second electrode 120, so that the reflective metal is included in the first electrode 110, and so that the second electrode 120 is formed as a transparent electrode or by a semi-transmissive metal, the display device of the present application can be implemented as a top emission type display device. Figure 8

[0112] ​Alternatively, the color filter may be omitted, and both the first electrode 110 and the second electrode 120 may be formed as transparent electrodes, thereby realizing a transparent organic light emitting device.

[0113] like Figure 9 As shown in , each sub-pixel SP may include a white light emitting device OLED, a driving transistor DT, a plurality of switching transistors and a capacitor Cst. The plurality of switching transistors may include a first switching transistor ST1 and a second switching transistor ST2. For ease of description, Figure 9 Only pixels P connected to the jth data line Dj (j is an integer of 2 or greater), the qth reference voltage line Rq (q is an integer of 2 or greater), the kth gate line Gk (k is an integer of 2 or greater), and the kth initialization line SEk are shown.

[0114] The white light-emitting device OLED emits light using a current supplied by the driving transistor DT. A first electrode of the white light-emitting device OLED may be connected to a source electrode of the driving transistor DT, and a second electrode of the white light-emitting device OLED may be connected to a first power voltage line VSSL through which a first power voltage is supplied. The first power voltage line VSSL may be a low-level voltage line through which a low-level power voltage is supplied.

[0115] The driving transistor DT is disposed between the white light-emitting device OLED and a second power voltage line VDDL, through which a second power voltage is supplied. The driving transistor DT controls the current flowing from the second power voltage line VDDL to the white light-emitting device OLED based on the voltage difference between the gate electrode and the source electrode of the driving transistor DT. The gate electrode of the driving transistor DT may be connected to the first electrode of the first switching transistor ST1, the source electrode of the driving transistor DT may be connected to the second power voltage line VDDL, and the drain electrode of the driving transistor DT may be connected to the first electrode of the white light-emitting device OLED. The second power voltage line VDDL may be a high-level voltage line through which a high-level power voltage is supplied.

[0116] The first switching transistor ST1 can be turned on by the kth gate signal of the kth gate line Gk and can provide the voltage of the jth data line Dj to the gate electrode of the driving transistor DT. The gate electrode of the first switching transistor ST1 can be connected to the kth gate line Gk, the source electrode of the first switching transistor ST1 can be connected to the gate electrode of the driving transistor DT, and the drain electrode of the first switching transistor ST1 can be connected to the jth data line Dj.

[0117] The second switching transistor ST2 may be turned on by the kth initialization signal of the kth initialization line SEk and may connect the qth reference voltage line Rq to the drain electrode of the driving transistor DT. A gate electrode of the second switching transistor ST2 may be connected to the kth initialization line SEk, a first electrode of the second switching transistor ST2 may be connected to the qth reference voltage line Rq, and a second electrode of the second switching transistor ST2 may be connected to the drain electrode of the driving transistor DT.

[0118] The capacitor Cst is formed between the gate electrode and the source electrode of the driving transistor DT and stores a differential voltage between the gate voltage and the source voltage of the driving transistor DT.

[0119] One electrode of the capacitor Cst can be connected to the gate electrode of the driving transistor DT and the source electrode of the first switching transistor ST1, and the other electrode of the capacitor Cst can be connected to the source electrode of the driving transistor DT, the drain electrode of the second switching transistor ST2 and the first electrode of the white light emitting device OLED.

[0120] The driving transistor DT, the first switching transistor ST1 and the second switching transistor ST2 of each sub-pixel P may be formed as thin film transistors. Figure 9 , the driving transistor DT, the first switching transistor ST1, and the second switching transistor ST2 of each sub-pixel P are formed as N-type semiconductor transistors having N-type semiconductor characteristics, but the embodiments of the present invention are not limited thereto. That is, the driving transistor DT, the first switching transistor ST1, and the second switching transistor ST2 of each sub-pixel P may be formed as P-type semiconductor transistors having P-type semiconductor characteristics.

[0121] In the present disclosure, since the phosphorescent light-emitting stack is provided with a red light-emitting layer, a yellow-green light-emitting layer, and a green light-emitting layer, rich color representation can be achieved. In addition, the yellow-green light-emitting layer can be formed to have the maximum thickness, thereby improving efficiency as the color changes when representing white.

[0122] A white light-emitting device according to one embodiment of the present disclosure may include: a first electrode and a second electrode facing each other across a substrate; a first stack disposed between the first electrode and the first charge generation layer, the first stack emitting first light; and a second stack disposed between the first charge generation layer and the second electrode, the second stack including first to third light-emitting layers stacked one above the other. The first to third light-emitting layers may emit light such that the wavelength of the light gradually decreases in a direction away from the first stack. The thickness of the third light-emitting layer may be less than the thickness of the first light-emitting layer or the thickness of the second light-emitting layer.

[0123] Each of the first to third light-emitting layers may be a phosphorescent light-emitting layer. The total thickness of the first to third light-emitting layers may be to And the thickness of the third light emitting layer may be 20% to 30% of the total thickness of the first to third light emitting layers.

[0124] A thickness of the third light emitting layer at an edge region of the substrate may be greater than a thickness of the third light emitting layer at a central region of the substrate.

[0125] The thickness of the first light emitting layer may be 29.5% to 34.1% of the total thickness of the first to third light emitting layers.

[0126] The first light-emitting layer may emit a second light having an emission peak in the range of 590 nm to 650 nm. The second light-emitting layer may emit a third light having an emission peak in the range of 540 nm to 590 nm. The third light-emitting layer may emit a fourth light having an emission peak in the range of 510 nm to 560 nm. The wavelength of the fourth light may be longer than that of the first light.

[0127] The first light may have an emission peak within a range of 430 nm to 490 nm, and the first stack may include a fourth light emitting layer emitting the first light.

[0128] The white light emitting device may further include a second charge generation layer and a third stack provided on the second stack, the third stack including a fifth light emitting layer that emits the first light.

[0129] The thickness of the first light emitting layer may be 65% to 75% of the thickness of the second light emitting layer. The thickness of the third light emitting layer may be 45% to 55% of the thickness of the second light emitting layer.

[0130] The first light-emitting layer may be a red light-emitting layer, the second light-emitting layer may be a yellow-green light-emitting layer, and the third light-emitting layer may be a green light-emitting layer. The thickness of the first light-emitting layer may be 65% to 75% of the thickness of the second light-emitting layer. The thickness of the third light-emitting layer may be 45% to 55% of the thickness of the second light-emitting layer.

[0131] According to one embodiment of the present disclosure, a light-emitting display device may include: a substrate including a plurality of sub-pixels; a first electrode at each of the plurality of sub-pixels on the substrate; a second electrode disposed opposite the first electrode across the plurality of sub-pixels; a first stack between the first electrode and a first charge generation layer across the plurality of sub-pixels, the first stack emitting first light; and a second stack between the first charge generation layer and the second electrode across the plurality of sub-pixels, the second stack including first to third light-emitting layers stacked in sequence. The first to third light-emitting layers may emit light such that the wavelength of the light gradually decreases in a direction away from the first stack. The thickness of the third light-emitting layer may be less than the thickness of the first light-emitting layer or the thickness of the second light-emitting layer.

[0132] Each of the first to third light-emitting layers may be a phosphorescent light-emitting layer. The total thickness of the first to third light-emitting layers may be to The thickness of the third light emitting layer may be 20% to 30% of the total thickness of the first to third light emitting layers.

[0133] The thickness of the third light emitting layer in the sub-pixel located at the edge region of the substrate may be greater than the thickness of the third light emitting layer in the sub-pixel located at the center region of the substrate.

[0134] The thickness of the first light emitting layer may be 29.5% to 34.1% of the total thickness of the first to third light emitting layers.

[0135] The first light-emitting layer may emit a second light having an emission peak within a range of 590 nm to 650 nm. The second light-emitting layer may emit a third light having an emission peak within a range of 540 nm to 590 nm. The third light-emitting layer may emit a fourth light having an emission peak within a range of 510 nm to 560 nm. The wavelength of the fourth light may be longer than that of the first light.

[0136] The first light may have an emission peak within a range of 430 nm to 490 nm.The first stack may include a fourth light emitting layer that emits the first light.

[0137] The light emitting display device may further include a second charge generation layer provided on the second stack, and a third stack including a fifth light emitting layer that emits the first light.

[0138] The light emitting display device may further include a thin film transistor and a color filter layer between the substrate and the first electrode, the thin film transistor being connected to the first electrode.

[0139] The thickness of the first light emitting layer may be 65% to 75% of the thickness of the second light emitting layer. The thickness of the third light emitting layer may be 45% to 55% of the thickness of the second light emitting layer.

[0140] The first light-emitting layer may be a red light-emitting layer, the second light-emitting layer may be a yellow-green light-emitting layer, and the third light-emitting layer may be a green light-emitting layer. The thickness of the first light-emitting layer may be 65% to 75% of the thickness of the second light-emitting layer, and the thickness of the third light-emitting layer may be 45% to 55% of the thickness of the second light-emitting layer.

[0141] As apparent from the above description, the white light emitting device according to the present invention and the light emitting display apparatus including the same have the following effects.

[0142] First, because the phosphorescent light-emitting stack is provided with a red light-emitting layer, a yellow-green light-emitting layer, and a green light-emitting layer, rich color expression can be achieved. In addition, the yellow-green light-emitting layer is formed to have the maximum thickness, thereby improving efficiency with color changes when expressing white.

[0143] Second, among the different colored stacked luminescent layers in the phosphorescent stack, the green luminescent layer is formed to have the smallest thickness. Therefore, the green luminescent layer is thinner than the total thickness of the phosphorescent layers in the stack, thereby reducing the effect of the thickness difference of the green luminescent layer on the color representation in the display area. As a result, color anomalies in the edge areas of the display area can be prevented.

[0144] Third, the ratio of the thickness of the red light-emitting layer and the green light-emitting layer to the thickness of the yellow-green light-emitting layer is appropriately set so that: in the edge area and the center area in the display area of ​​the substrate, the degree of change of the color coordinates at low current density is similar to the degree of change of the color coordinates at high current density, thereby preventing color abnormalities when driving at low current density.

[0145] It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Therefore, the present invention is intended to cover modifications and variations of the present invention as long as they are within the scope of the appended claims and their equivalents.

Claims

1. A light-emitting display device, comprising: a substrate comprising a plurality of sub-pixels; a first electrode at each sub-pixel of the plurality of sub-pixels; a second electrode opposite to the first electrode, the second electrode being above the plurality of sub-pixels; a first stack disposed between the first electrode and the first charge generation layer, the first stack emitting first light; as well as a second stack provided between the first charge generation layer and the second electrode, the second stack comprising a red light-emitting layer, a yellow-green light-emitting layer and a green light-emitting layer stacked in sequence, The red light-emitting layer, the yellow-green light-emitting layer, and the green light-emitting layer emit light such that the wavelength of the light gradually shortens in a direction away from the first stacked layer. Among the red light-emitting layer, the yellow-green light-emitting layer and the green light-emitting layer, the green light-emitting layer is the thinnest and the yellow-green light-emitting layer is the thickest. wherein the red light emitting layer, the yellow-green light emitting layer and the green light emitting layer are completely disposed above the plurality of sub-pixels, Wherein, in the front view of the light-emitting display device, the display area of ​​the substrate includes a central area and an edge area, and the edge area includes a top edge area, a bottom edge area, a left edge area and a right edge area, and The thickness of the green light-emitting layer at the sub-pixel in each of the top edge region, the bottom edge region, the left edge region, and the right edge region is greater than the thickness of the green light-emitting layer in the central region.

2. The light-emitting display device according to claim 1, wherein Each of the red light-emitting layer, the yellow-green light-emitting layer, and the green light-emitting layer is a phosphorescent light-emitting layer, The total thickness of the red light-emitting layer, the yellow-green light-emitting layer and the green light-emitting layer is to as well as The thickness of the green light-emitting layer is 20% to 30% of the total thickness of the red light-emitting layer, the yellow-green light-emitting layer and the green light-emitting layer.

3. The light-emitting display device according to claim 1, wherein the red light emitting layer, the yellow-green light emitting layer, and the green light emitting layer include phosphorescent dopants independently different from each other and emit light, The phosphorescent dopants in the red light-emitting layer, the yellow-green light-emitting layer, and the green light-emitting layer have differences in triplet energy levels required for excitation.

4. The light-emitting display device according to claim 2, wherein: The thickness of the red light emitting layer is 29.5% to 34.1% of the total thickness of the red light emitting layer, the yellow-green light emitting layer, and the green light emitting layer.

5. The light-emitting display device according to claim 1, wherein The red light emitting layer emits a second light having an emission peak in the range of 590 nm to 650 nm, The yellow-green light emitting layer emits a third light having an emission peak in the range of 540 nm to 590 nm. wherein the green light emitting layer emits a fourth light having an emission peak in the range of 510 nm to 560 nm, and The wavelength of the fourth light is longer than the wavelength of the first light.

6. The light-emitting display device according to claim 1, wherein: The first light has an emission peak in the range of 430 nm to 490 nm, and The first stack includes a first blue light-emitting layer that emits the first light.

7. The light-emitting display device according to claim 1, further comprising: A second charge generation layer and a third stack are provided on the second stack, the third stack including a second blue light emitting layer that emits the first light.

8. The light-emitting display device according to claim 1, wherein: The thickness of the red light emitting layer is 65% to 75% of the thickness of the yellow-green light emitting layer, and The thickness of the green light-emitting layer is 45% to 55% of the thickness of the yellow-green light-emitting layer.

9. A light-emitting display device, comprising: a substrate comprising a plurality of sub-pixels; a first electrode at each sub-pixel of the plurality of sub-pixels; a second electrode opposite to the first electrode, the second electrode being above the plurality of sub-pixels; a first stack disposed between the first electrode and the first charge generation layer, the first stack emitting first light; as well as a second stack provided between the first charge generation layer and the second electrode, the second stack comprising a red light-emitting layer, a yellow-green light-emitting layer and a green light-emitting layer stacked in sequence, The red light-emitting layer, the yellow-green light-emitting layer, and the green light-emitting layer emit light such that the wavelength of the light gradually shortens in a direction away from the first stacked layer. wherein the red light emitting layer, the yellow-green light emitting layer and the green light emitting layer are completely disposed above the plurality of sub-pixels, The thickness of the red light-emitting layer is 65% to 75% of the thickness of the yellow-green light-emitting layer. The thickness of the green light-emitting layer is 45% to 55% of the thickness of the yellow-green light-emitting layer. Wherein, in the front view of the light-emitting display device, the display area of ​​the substrate includes a central area and an edge area, and the edge area includes a top edge area, a bottom edge area, a left edge area and a right edge area, and The thickness of the green light-emitting layer at the sub-pixel in each of the top edge region, the bottom edge region, the left edge region, and the right edge region is greater than the thickness of the green light-emitting layer in the central region.

10. A light-emitting display device, comprising: a substrate including a plurality of red sub-pixels, a plurality of green sub-pixels, a plurality of blue sub-pixels, and a plurality of white sub-pixels; a first electrode on the substrate at each of the plurality of red sub-pixels, the plurality of green sub-pixels, the plurality of blue sub-pixels, and the plurality of white sub-pixels; a second electrode disposed above the plurality of red sub-pixels, the plurality of green sub-pixels, the plurality of blue sub-pixels, and the plurality of white sub-pixels and opposite to the first electrode; a first stack disposed between the first electrode and the first charge generation layer, the first stack emitting first light; as well as a second stacked layer between the first charge generation layer and the second electrode above the plurality of sub-pixels, the second stacked layer comprising a red light-emitting layer, a yellow-green light-emitting layer, and a green light-emitting layer stacked in sequence; The red light-emitting layer, the yellow-green light-emitting layer, and the green light-emitting layer emit light such that the wavelength of the light gradually shortens in a direction away from the first stacked layer. wherein the red light emitting layer, the yellow-green light emitting layer, and the green light emitting layer are provided over the plurality of red sub-pixels, the plurality of green sub-pixels, the plurality of blue sub-pixels, and the plurality of white sub-pixels, and wherein, among the red light emitting layer, the yellow-green light emitting layer, and the green light emitting layer, the green light emitting layer is the thinnest, and the yellow-green light emitting layer is the thickest, Wherein, in the front view of the light-emitting display device, the display area of ​​the substrate includes a central area and an edge area, and the edge area includes a top edge area, a bottom edge area, a left edge area and a right edge area, and The thickness of the green light-emitting layer at the sub-pixel in each of the top edge region, the bottom edge region, the left edge region, and the right edge region is greater than the thickness of the green light-emitting layer in the central region.

11. The light-emitting display device according to claim 10, wherein: Each of the red light-emitting layer, the yellow-green light-emitting layer, and the green light-emitting layer includes a phosphorescent light-emitting layer, The total thickness of the red light-emitting layer, the yellow-green light-emitting layer and the green light-emitting layer is to wherein the thickness of the green light emitting layer is 20% to 30% of the total thickness of the red light emitting layer, the yellow-green light emitting layer, and the green light emitting layer; and The thickness of the red light emitting layer is 29.5% to 34.1% of the total thickness of the red light emitting layer, the yellow-green light emitting layer, and the green light emitting layer.

12. The light-emitting display device according to claim 10, wherein: The thickness of the green light-emitting layer in the red sub-pixels, green sub-pixels, blue sub-pixels and white sub-pixels located in the edge area of ​​the substrate is greater than the thickness of the green light-emitting layer in the red sub-pixels, green sub-pixels, blue sub-pixels and white sub-pixels located in the central area of ​​the substrate.

13. The light-emitting display device according to claim 11, wherein: the red light emitting layer, the yellow-green light emitting layer, and the green light emitting layer include phosphorescent dopants independently different from each other and emit light, The phosphorescent dopants in the red light-emitting layer, the yellow-green light-emitting layer, and the green light-emitting layer have differences in triplet energy levels required for excitation.

14. The light-emitting display device according to claim 10, wherein: The red light emitting layer emits a second light having an emission peak in the range of 590 nm to 650 nm, The yellow-green light emitting layer emits a third light having an emission peak in the range of 540 nm to 590 nm. wherein the green light emitting layer emits a fourth light having an emission peak in the range of 510 nm to 560 nm, and The wavelength of the fourth light is longer than the wavelength of the first light.

15. The light-emitting display device according to claim 10, wherein: The first light has an emission peak in the range of 430 nm to 490 nm, and The first stack includes a first blue light-emitting layer that emits the first light.

16. The light-emitting display device according to claim 10, further comprising: A second charge generation layer and a third stack are provided on the second stack, the third stack including a second blue light emitting layer that emits the first light.

17. The light-emitting display device according to claim 10, further comprising: a thin film transistor over the substrate at each of the plurality of red sub-pixels, the plurality of green sub-pixels, the plurality of blue sub-pixels, and the plurality of white sub-pixels; a first protective film above the thin film transistor; a color filter over the thin film transistor; a second protective film over the color filter; The first electrode above the second protective film is connected to the thin film transistor through contact holes in the first protective film and the second protective film.

18. The light-emitting display device according to claim 17, wherein: The color filters include red color filters at the plurality of red sub-pixels, green color filters at the plurality of green sub-pixels, and blue color filters at the plurality of blue sub-pixels, and There is no color filter at the white sub-pixel.

19. The light-emitting display device according to claim 10, wherein: The thickness of the red light emitting layer is 65% to 75% of the thickness of the yellow-green light emitting layer, and The thickness of the green light-emitting layer is 45% to 55% of the thickness of the yellow-green light-emitting layer.

20. The light-emitting display device according to claim 17, wherein: The color filter is provided between the first protection film and the second protection film.

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