Light emitting device and light emitting display device including the same

Abstract

A light-emitting device is disclosed to prevent defects in the observation of light with a specific color when switching from a black state to a low grayscale state. The light-emitting device includes a first electrode and a second electrode facing each other, and a green light-emitting stack including a hole transport layer, a green light-emitting layer and an electron transport layer disposed between the first electrode and the second electrode. The green light-emitting layer includes a hole transport matrix, an electron transport matrix and a green dopant. The HOMO level of the green dopant is lower than the HOMO level of the hole transport matrix and higher than the HOMO level of the electron transport matrix, and the HOMO level of the electron transport matrix is ​​higher than the HOMO level of the electron transport layer.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of Korean Patent Application No. 10-2024-019855, filed on December 24, 2024, which is incorporated herein by reference as if fully set forth herein. Technical Field

[0003] This disclosure relates to a light-emitting device with improved image quality and efficiency, and a light-emitting display device including the light-emitting device. Background Technology

[0004] With the advent of the information society, displays used to visually represent electrical information signals have developed rapidly. In response, various display devices with excellent performance characteristics, such as thinness, light weight, and low power consumption, are being developed.

[0005] Among them, light-emitting display devices that do not require a separate light source to achieve compactness and clear colors and have light-emitting devices in the display panel are considered competitive applications.

[0006] The light-emitting device may include an anode and a cathode facing each other as electrodes, a light-emitting layer between the anode and the cathode, and a common layer for transferring holes and electrons to the light-emitting layer.

[0007] Simultaneously, the light-emitting device may include, for example, various functional layers in a common layer for various functions. These functional layers include a hole transport layer for transferring holes to the light-emitting layer and an electron transport layer for transferring electrons to the light-emitting layer. Summary of the Invention

[0008] Therefore, this disclosure relates to a light-emitting device and a light-emitting display device including the light-emitting device, which substantially eliminates one or more problems caused by the limitations and disadvantages of related technologies.

[0009] The light-emitting device may include a light-emitting layer that emits different colors of light to represent various colors.

[0010] Meanwhile, recently, light-emitting display devices, including those with different light-emitting layers, have been experiencing flickering issues when switching from a black state to a low grayscale state, especially when a particular color is prominent.

[0011] One object of this disclosure is to provide a light-emitting device that can improve poor image quality when a particular color is prominent when switching from an off state (black state) to a low grayscale state in a structure including a light-emitting layer that emits light of different colors.

[0012] Another object of this disclosure is to provide a light-emitting display device that can improve the efficiency of green light-emitting stacks that play a key role in color performance.

[0013] Further advantages, objects, and features of this disclosure will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art upon examination of the following, or may be learned by practice of this disclosure. The objects and other advantages of this disclosure may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0014] To achieve these and other advantages and in accordance with the purposes of this disclosure, as embodied and broadly described herein, a light-emitting device includes a first electrode and a second electrode facing each other, and a green light-emitting stack including a hole transport layer, a green light-emitting layer, and an electron transport layer disposed between the first electrode and the second electrode, wherein the green light-emitting layer includes a hole transport matrix (host), an electron transport matrix, and a green dopant, the HOMO level of the green dopant being lower than the HOMO level of the hole transport matrix and higher than the HOMO level of the electron transport matrix, and the HOMO level of the electron transport matrix being higher than the HOMO level of the electron transport layer.

[0015] According to another aspect of this disclosure, a light-emitting display device includes: a substrate comprising a plurality of sub-pixels, a pixel circuit at each of the plurality of sub-pixels, the pixel circuit including at least one transistor, and a light-emitting device connected to the pixel circuit at at least one of the sub-pixels.

[0016] It should be understood that the foregoing general description and the following detailed description of this disclosure are exemplary and explanatory, and are intended to provide further explanation of the claimed disclosure. Attached Figure Description

[0017] The accompanying drawings are included to provide a further understanding of this disclosure and are incorporated in and constitute a part of this application. The drawings illustrate embodiments of the disclosure and, together with the specification, serve to explain the principles of the disclosure. In the drawings:

[0018] Figure 1 This is a cross-sectional view showing a light-emitting device according to an embodiment of the present disclosure;

[0019] Figure 2 It is a band structure diagram of stacked green luminescent particles;

[0020] Figure 3A and Figure 3B Hole transport is shown in a first green dopant having a HOMO energy level higher than that of the hole transport matrix and a green dopant having a HOMO energy level lower than that of the hole transport matrix.

[0021] Figure 4A This is a graph illustrating the JV characteristics of the HOD device when the active layer includes the hole transport matrix GHH, the first green dopant GD1, and the green dopant GD according to embodiments of the present disclosure;

[0022] Figure 4B This is a graph illustrating the JV characteristics of an EOD device when the active layer includes the electron transport matrix GEHA, the first green dopant GD1, and the green dopant GD, as described in the embodiments of this disclosure.

[0023] Figures 5A to 5D These are band diagrams of experimental examples 1 to 4, which show different materials for the green dopants and electron transport matrix in the green emitting layer of the green emitting stack.

[0024] Figure 6 The movement of charge carriers in the green light-emitting layer of the light-emitting device according to Experimental Example 1, comprising a hole transport matrix, a first electron transport matrix and a first green dopant, is shown;

[0025] Figure 7 The illustration shows the movement of charge carriers from a green light-emitting layer comprising a hole transport matrix, an electron transport matrix, and a green dopant in a light-emitting device according to an embodiment of the present disclosure;

[0026] Figure 8 The graphs show the CV characteristics of the green light emission stacks in Experiments 1 to 4;

[0027] Figures 9A to 9C This is a graph showing the brightness of Experiments 2 to 4 when switching from a black state to a low grayscale state, compared to Experiment 1;

[0028] Figure 10 This is a schematic diagram illustrating an electron transport substrate according to an embodiment of the present disclosure;

[0029] Figure 11 This is a cross-sectional view showing a light-emitting device according to another embodiment of the present disclosure;

[0030] Figure 12 This is a cross-sectional view showing a light-emitting display device according to an embodiment of the present disclosure; and

[0031] Figure 13 This is a cross-sectional view showing a light-emitting display device according to another embodiment of the present disclosure. Detailed Implementation

[0032] The advantages and features of this disclosure, as well as methods for achieving these advantages and features, will become apparent from the exemplary embodiments described in detail herein with reference to the accompanying drawings. This disclosure should not be construed as limited to the exemplary embodiments disclosed below, and may be embodied in various different forms. Therefore, these exemplary embodiments are set forth only to make this disclosure sufficiently complete and to help those skilled in the art fully understand the scope of this disclosure. The scope of protection of this disclosure is defined by the claims and their equivalents.

[0033] In the following description of this disclosure, detailed descriptions of known steps, components, functions, techniques, and configurations may be omitted where such omissions would unnecessarily obscure the essential points of this disclosure. Furthermore, the names of elements used in the following description have been chosen for clarity of description and may differ from the names of elements in actual products. In addition, numerous specific details are set forth in the following detailed description of this disclosure to provide a full and thorough understanding of it. However, it should be understood that this disclosure can be practiced without these specific details. In other instances, known methods, processes, components, and circuits have not been described in detail to avoid unnecessarily obscuring aspects of this disclosure.

[0034] The shapes, dimensions, ratios, angles, quantities, etc., shown in the accompanying drawings to describe various exemplary embodiments of this disclosure are given by way of example only. This disclosure is not limited to the illustrations in the accompanying drawings.

[0035] In this specification, one or more components may be added where terms such as “comprising,” “having,” or “including” are used, unless a term such as “only” is used. As used herein, the term “and / or” includes a single associated listed item as well as any and all combinations of two or more associated listed items.

[0036] When a phrase such as "at least one of..." is used before a list of elements, the entire list of elements can be modified without modifying any individual element of the list. The term "at least one" should be understood to include any and all combinations of one or more related listed items. For example, "at least one of the first, second, and third elements" means all three listed elements, any combination of any two of the three elements, and each individual element, as well as combinations of the first, second, and third elements.

[0037] The terminology used herein is for describing specific aspects and is not intended to limit this disclosure. As used herein, the terms “a” and “an” used to describe elements in the singular form are intended to include multiple elements. Unless the context clearly indicates otherwise, elements described in the singular form are intended to include multiple elements, and vice versa.

[0038] When interpreting components or values, even if no explicit description of such error or tolerance range is provided, the components or values ​​will be interpreted as including the error or tolerance range.

[0039] In describing various exemplary embodiments of this disclosure, terms such as “on,” “above,” “below,” and “adjacent” are used to describe the positional relationship between two elements. Unless “immediately,” “directly,” or “closely” is used, at least one intermediate element may exist between two elements. It will be understood that when an element or layer is referred to as being “connected to” or “coupled to” another element or layer, it may be directly connected to or coupled to the other element or layer, or one or more intermediate elements or layers may exist.

[0040] In describing various exemplary embodiments of this disclosure, when using terms such as “after,” “following,” “next,” and “before” to describe the temporal relationship between two events, another event may occur in between, unless more restrictive terms such as “only,” “immediately,” or “directly” are used.

[0041] In describing the various exemplary embodiments of this disclosure, terms such as “first” and “second” may be used to describe various components. These terms are intended to distinguish identical or similar components from one another and do not limit the components. Therefore, throughout the specification, unless otherwise specifically stated, a “first” component may be the same as a “second” component within the technical concept of this disclosure.

[0042] Features of the various embodiments of this disclosure may be coupled or combined with each other in part or in whole, and, as will be fully understood by those skilled in the art, may interoperate differently with each other and be technically driven. Embodiments of this disclosure may be performed independently of each other, or may be performed together in an interdependent relationship.

[0043] As used herein, the terms “LUMO (lowest unoccupied molecular orbital) level” and “HOMO (highest occupied molecular orbital) level” of a layer refer to the LUMO and HOMO levels of the material layer (e.g., the matrix material) that occupies most of the weight of the layer, unless the context clearly indicates that the LUMO and HOMO levels refer to the LUMO and HOMO levels of the dopant material that doped the layer, respectively.

[0044] Here, the HOMO level is obtained by measuring the voltage corresponding to the first peak of electron discharge from the target material via cyclic voltammetry (CV) and comparing it with a reference material whose HOMO level is known. For example, the HOMO level of a material can be measured based on the known oxidation and reduction potentials of the material.

[0045] As used herein, the term "doped" layer refers to a layer comprising a first material and a second material having physical properties different from the first material (e.g., n-type and p-type materials, or organic and inorganic substances). In addition to differences in properties, the amounts of the first and second materials in the doped layer can also differ. For example, the matrix material can be the dominant component, while the dopant material can be a minor component. The first material constitutes the majority of the weight of the doped layer. The second material can be added in amounts less than 30% by weight, based on the total weight of the first material in the doped layer. Considering the weight ratio, a "doped" layer can be a layer used to distinguish the matrix material from the dopant material of a given layer. For example, if all the materials constituting a layer are organic, and at least one of the materials constituting the layer is n-type and another is p-type, the layer is considered a "doped" layer when the n-type material is present in amounts less than 30 wt%, or when the p-type material is present in amounts less than 30 wt%.

[0046] Furthermore, the term "undoped" refers to a layer that has not been "doped." For example, a layer can be considered "undoped" when it comprises a single material or a mixture of materials having the same properties as each other. For example, a layer is considered "undoped" if at least one of the materials constituting it is p-type and none of the materials constituting it is n-type. For example, a layer is considered "undoped" if at least one of the materials constituting it is an organic material and none of the materials constituting it is an inorganic material.

[0047] In this disclosure, an electroluminescence (EL) spectrum can be calculated by multiplying (a) a photoluminescence (PL) spectrum by (b) an external coupling or emissivity spectrum curve, the photoluminescence (PL) spectrum applying the inherent properties of the luminescent material (such as a dopant material or matrix material included in an organic emitting layer), the spectrum curve being determined by the structure and optical properties of the organic light-emitting device including the thickness of an organic layer (such as, for example, an electron transport layer).

[0048] In the following, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. When adding reference numerals to elements of each drawing, the same reference numerals may refer to the same elements even though the same elements are shown in other drawings.

[0049] Figure 1 This is a cross-sectional view showing a light-emitting device according to an embodiment of the present disclosure. Figure 2 It is a band structure of green luminescent stacks. Figure 3A and Figure 3B Hole transport is shown with a first green dopant having a HOMO energy level higher than that of the hole transport matrix and a green dopant having a HOMO energy level lower than that of the hole transport matrix.

[0050] The light-emitting device according to an embodiment of the present disclosure is disposed in at least one sub-pixel of the light-emitting display device.

[0051] like Figure 1 As shown, the light-emitting device according to an embodiment of the present disclosure includes a first electrode AND and a second electrode CAT facing each other, and a plurality of light-emitting stacks S1, S2, S3 and S4 between the first electrode AND and the second electrode CAT. The light-emitting device may include charge-generating layers CGL1, CGL2 and CGL3 between adjacent light-emitting stacks in the plurality of light-emitting stacks S1, S2, S3 and S4.

[0052] The first electrode AND can be used as the anode, and the second electrode CAT can be used as the cathode.

[0053] At least one of the first electrode AND and the second electrode CAT is transparent or semi-transparent, and light generated in the light-emitting device is transmitted through the transparent or semi-transparent electrode. For example, when the first electrode AND includes a reflective electrode and the second electrode CAT includes a semi-transparent or transparent electrode, the light-emitting device can emit light through the second electrode CAT. As another example, when the first electrode AND includes a transparent electrode and the second electrode CAT includes a reflective electrode, the light-emitting device can emit light through the first electrode AND. As yet another example, the first electrode AND and the second electrode CAT can be transparent or semi-transparent electrodes, such that the light-emitting device ED can emit light in both directions of the first electrode AND and the second electrode CAT.

[0054] The first electrode AND can be connected to a thin-film transistor of a pixel circuit at at least one of a plurality of sub-pixels disposed on a substrate. The pixel circuit is disposed at each of the plurality of sub-pixels and includes at least one transistor. The second electrode CAT can be provided to each sub-pixel collectively and can receive a common voltage signal from at least the outside.

[0055] Each charge generation layer CGL1, CGL2, and CGL3 may include an n-type charge generation layer NCGL and a p-type charge generation layer PCGL. The n-type charge generation layer NCGL generates electrons and supplies electrons to adjacent light-emitting stacks, and the p-type charge generation layer PCGL generates holes and supplies holes to adjacent light-emitting stacks.

[0056] Figure 1The example shown illustrates four light-emitting stacks S1, S2, S3, and S4 disposed between the first electrode AND and the second electrode CAT, but the embodiments of this disclosure are not limited thereto. That is, the light-emitting device of the embodiments of this disclosure may include two, three or more, or five or more light-emitting stacks between the first electrode AND and the second electrode CAT. When the light-emitting device of the embodiments of this disclosure includes two or more light-emitting stacks, one light-emitting stack may include a green light-emitting layer GEML.

[0057] Figure 1 The light-emitting device illustrates an example of a first light-emitting stack S1 (or red light-emitting stack) including a red light-emitting layer REML, a second light-emitting stack S2 (or first blue light-emitting stack) including a first blue light-emitting layer BEML1, a third light-emitting stack S3 (or green light-emitting stack) including a green light-emitting layer GEML, and a fourth light-emitting stack S4 (or second blue light-emitting stack) including a second blue light-emitting layer BEML2.

[0058] Therefore, the light-emitting device ED, which includes light-emitting stacks S1, S2, S3 and S4 that emit light of different colors, emits white light through at least one of the first electrode AND and the second electrode CAT.

[0059] Each of the first to fourth light-emitting stacks S1 to S4 has hole transport common layers CML11, CML12, CML13, and CML14 on the underside of the light-emitting layers REML, BEML1, GEML, and BEML2, and electron transport common layers CML21, CML22, CML23, and CML24 on the upper side of the light-emitting layers.

[0060] The hole transport common layers CML11, CML12, CML13, and CML14 may include a hole injection layer and a hole transport layer (see [link]). Figure 2The structure includes an HTL (electron blocking layer), an electron blocking layer, etc. A hole injection layer may optionally be disposed on a first light-emitting stack S1 in contact with the first electrode AND. In this case, the hole injection layer can be used to transport holes from the first electrode AND to the red light-emitting layer REML. A hole transport layer can transfer holes supplied from the first electrode AND or charge generation layers CGL1, CGL2, and CGL3 to each of the light-emitting layers REML, BEML1, GEML, and BEML2. An electron blocking layer can be used to block electrons from being transported from the light-emitting layers REML, BEML1, GEML, and BEML2 to the hole transport common layers CML11, CML12, CML13, and CML14. For example, a red light-emitting stack S1 including the red light-emitting layer REML, a first charge generation layer CGL1, a first blue light-emitting stack S2 including the first blue light-emitting layer BEML1, and a second charge generation layer CGL2 may be disposed between the first electrode AND and the hole transport layer CML13 of the green light-emitting stack S3. For example, the hole transport layer CML13 of the green light-emitting stack S3 can contact the p-type charge generation layer of the second charge generation layer CGL2.

[0061] An electron blocking layer may or may not be selectively disposed in each of the light-emitting stacks S1, S2, S3 and S4.

[0062] In some cases, in addition to the hole transport layer or electron blocking layer between the first electrode AND or charge generation layers CGL1, CGL2 and CGL3 and each of the light-emitting layers REML, BEML1, GEML, BEML2, a separate optical compensation layer or hole transport auxiliary layer may be provided.

[0063] The hole transport common layers CML11, CML12, CML13, and CML14 may include hole transport materials. At least one of the hole transport common layers CML11, CML12, CML13, and CML14 may include multiple layers containing different materials.

[0064] Electron transport common layers CML21, CML22, CML23, and CML24 may include a hole blocking layer and an electron transport layer (see [link to documentation]). Figure 2The electron transport layer (ETL) and electron injection layer are used in the fourth light-emitting stack S4, which is in contact with the second electrode CAT. In this case, the electron injection layer is used to inject electrons from the second electrode CAT in the direction of the second blue light-emitting layer BEML2. The electron transport layer (ETL) is used to transfer electrons from the second electrode CAT in each light-emitting stack in the direction of each light-emitting layer. The hole blocking layer serves to restrict the escape of holes injected into the light-emitting layer in the direction of the electron transport layer. For example, the third charge generation layer CGL3 and the second blue light-emitting stack S4 including the second blue light-emitting layer BEML2 can be disposed between the electron transport layer CML23 of the green light-emitting stack S3 and the second electrode CAT. For example, the electron transport layer CML23 of the green light-emitting stack S3 can contact the n-type charge generation layer of the third charge generation layer CGL3.

[0065] Hole blocking layers may be optionally provided or not provided in each light-emitting stack.

[0066] The electron transport common layers CML21, CML22, CML23, and CML24 may include electron transport materials. At least one of the electron transport common layers CML21, CML22, CML23, and CML24 may be disposed in multiple layers comprising different materials.

[0067] Figure 1 The light-emitting device is implemented such that a first light-emitting stack is a red light-emitting stack emitting red light, a second light-emitting stack is a first blue light-emitting stack emitting blue light, a third light-emitting stack is a green light-emitting stack emitting green light, and a fourth light-emitting stack is a second blue light-emitting stack emitting blue light. For example, R / B1 / G / B2 light-emitting stacks are stacked and arranged in a direction from the first electrode AND to the second electrode CAT. However, the light-emitting device of the embodiments of this disclosure is not limited to this. For example, when multiple light-emitting stacks are arranged between the first electrode and the second electrode, ... Figure 1 The examples shown differ in their color arrangement. The red light-emitting stack, the green light-emitting stack, and the first blue light-emitting stack and the second blue light-emitting stack (R / G / B1 / B2) can be arranged sequentially between the first electrode and the second electrode, or the green light-emitting stack, the red light-emitting stack, and the first blue light-emitting stack and the second blue light-emitting stack (G / R / B1 / B2) can be arranged sequentially between the first electrode and the second electrode, or the first blue light-emitting stack, the red light-emitting stack, the green light-emitting stack and the second blue light-emitting stack (B1 / R / G / B2) can be arranged sequentially between the first electrode and the second electrode, or these stacks can be arranged in other orders.

[0068] Here, two blue light-emitting stacks are arranged in the light-emitting device to compensate for the relatively low blue efficiency compared to other colors. When the two blue light-emitting stacks are arranged between the first electrode AND and the second electrode CAT, the second blue light-emitting layer BEML2, which is closer to the second electrode CAT, can be thicker than the first blue light-emitting layer BEML1, which is closer to the first electrode AND. This compensates for the efficiency of the second blue light-emitting layer BEML2 located behind the first electrode AND.

[0069] When a voltage greater than a predetermined level is applied between the first electrode AND and the second electrode CAT, the light-emitting device comprising the first to fourth light-emitting stacks S1, S2, S3, and S4 described above emits white light. Each sub-pixel may also include a color filter outside the first or second electrode from which it emits light, such that each sub-pixel displays a different color.

[0070] Meanwhile, green has the best visibility and the highest brightness when representing white. Therefore, among different light-emitting stacks, the green light-emitting stack needs to have a higher brightness efficiency than other color light-emitting stacks. Therefore, the green light-emitting layer GEML of the green light-emitting stack can be thicker and have a greater doping amount than the light-emitting layers REML, BEML1, and BEML2 of other color light-emitting stacks.

[0071] In addition, the green luminescent layer GEML can include phosphorescent materials to improve efficiency.

[0072] refer to Figure 2 The configuration of the luminescent stack, including a green luminescent layer GEML that emits green light, will be described.

[0073] The green light-emitting stack may include a hole transport layer (HTL), a green light-emitting layer (GEML), and an electron transport layer (ETL) arranged in sequence.

[0074] The green luminescent layer GEML comprises a matrix mixture including a hole transport matrix GHH and an electron transport matrix GEH to facilitate hole and charge injection and movement properties, and includes a green dopant GD in the matrix mixture.

[0075] Figure 2 Band diagrams for the two materials used as the hole transport matrix GHH and the electron transport matrix GEH are shown separately. In practice, the hole transport matrix GHH and the electron transport matrix GEH are not separated in the green emitting layer GEML, but are mixed in a predetermined ratio. Here, the ratio of the hole transport matrix GHH to the electron transport matrix GEH refers to the volume ratio. Furthermore, the content of the green dopant GD is less than the total content of the hole transport matrix GHH and the electron transport matrix GEH. For example, the green dopant GD in the green emitting layer GEML may be present in an amount of 5 wt% to 25 wt% relative to the total weight of the green emitting layer GEML.

[0076] The green dopant GD is present in a predetermined amount in a common matrix including a hole transport matrix GHH and an electron transport matrix GEH. Thus, when observing the green emission layer GEML at different vertical heights between the hole transport layer HTL and the electron transport layer ETL, the content ratios of the hole transport matrix GHH, the electron transport matrix GEH, and the green dopant GD at each vertical height can be similar or substantially the same.

[0077] As Figure 1 shown, when the green emission stack is disposed in the third emission stack S3 and spaced apart from the first electrode AND by a predetermined distance, the content of the hole transport matrix GHH can be greater than the content of the electron transport matrix GEH, so that the recombination region within the green emission layer GEML can be adjusted. For example, the content ratio of the hole transport matrix GHH to the electron transport matrix GEH in the green emission layer GEML can be 7:3. In the green emission layer GEML of the third emission stack S3 that is farther from the first electrode AND than from the second electrode CAT, the content of the hole transport matrix GHH in the green emission layer GEML is greater than the content of the electron transport matrix GEH, such that the region where holes and electrons recombine does not bias towards the interface between the hole transport layer and the green emission layer, but is located within the green emission layer GEML.

[0078] The content ratio of the hole transport matrix GHH to the electron transport matrix GEH in the green emission stack GEML can be adjusted in consideration of the distance from the first electrode AND or the second electrode CAT, the thickness of the green emission layer GEML, and the distance from the n-type charge generation layer NCGL or the p-type charge generation layer PCGL of the adjacent charge generation layer. The content ratio of the hole transport matrix GHH to the electron transport matrix GEH in the green emission stack GEML can be adjusted within a range of 1:9 to 9:1.

[0079] In the green emission layer GEML of an embodiment of the present disclosure, as Figure 2 and Figure 3B shown, the green dopant GD has a deep HOMO energy level, and the HOMO energy level HOMO_GD of the green dopant GD is lower than the HOMO energy level HOMO_GHH of the hole transport matrix GHH in the green emission layer GEML. HOMO_GD < HOMO_GHH. The difference between the HOMO energy level of the green dopant and the HOMO energy level of the hole transport matrix is 0.15 eV or less.

[0080] The content of the green dopant GD in the green emission layer GEML can be higher than the content of the red dopant RD, the first blue dopant BD1, and the second blue dopant BD2 in each of the red emission layer REML, the first blue emission layer BEML1, and the second blue emission layer BEML2.

[0081] In addition, such as Figure 2 As shown, the HOMO level HOMO_GD of the green dopant GD is higher than the HOMO level HOMO_GEH of the electron transport matrix GEH (HOMO_GD>HOMO_GEH).

[0082] The HOMO level HOMO_GEH of the electron transport matrix GEH is higher than the HOMO level HOMO_ETL of the electron transport layer ETL adjacent to the green emitting layer GEML, and lower than the HOMO level of the green dopant GD, which has a deep HOMO level. Here, the HOMO level of the electron transport matrix GEH has a small difference of about 0.25 eV to 0.55 eV from the HOMO level of the green dopant GD.

[0083] Meanwhile, the electron transport matrix GEH has a LUMO level similar to that of the hole transport matrix GHH, and also has a wide band gap.

[0084] Among the materials contained in the green luminescent layer GEML, the electron transport matrix GEH has the widest band gap.

[0085] The LUMO level of the electron transport matrix GEH is closer to the LUMO level of the hole transport matrix GHH than the LUMO level LUMO_ETL of the electron transport layer ETL.

[0086] The HOMO level HOMO_GEH of the electron transport matrix GEH is closer to the HOMO level HOMO_ETL of the electron transport layer ETL than the HOMO level HOMO_GD of the green dopant GD.

[0087] Specifically, refer to Figure 3A and Figure 3B The hole transport behavior of a green emitting layer, including a first green dopant GD1 with high HOMO energy level characteristics and a green dopant GD with low HOMO energy level characteristics, will be described compared to the HOMO energy level HOMO_GHH of the hole transport matrix GHH.

[0088] Figure 3A The first green dopant GD1 is shown, which has a HOMO energy level lower than that of the hole transport matrix GHH.

[0089] according to Figure 3B The HOMO level of the green dopant GD in the embodiments of this disclosure is lower than that of the green dopant GD with the HOMO_GD level. Figure 3A The HOMO level HOMO_GD1 of the green dopant (hereinafter referred to as the first green dopant GD1) with general hole trap characteristics is shown. Figure 2 and Figure 3B As shown, the green dopant GD according to embodiments of this disclosure can have a HOMO level (HOMO_GD) that is lower than the HOMO level HOMO_HTL of the adjacent hole transport layer HTL. <HOMO_HTL)。

[0090] The HOMO level HOMO_GHH of the hole transport matrix GHH is similar to or lower than the HOMO level HOMO_HTL of the adjacent hole transport layer HTL. Since the green dopant GD has a lower HOMO level than the hole transport matrix GHH, it also has a lower HOMO level than the HOMO_HTL of the adjacent hole transport layer HTL. Therefore, electrons injected from the hole transport layer HTL into the green emitting layer GEML can disperse and move to the green dopant GD, the hole transport matrix GHH, and the electron transport matrix GEH, all of which have lower HOMO levels than the hole transport layer HTL HOMO_HTL. Furthermore, the hole transport matrix GHH, with its high hole mobility, along with the green dopant GD, can serve as a path for hole movement. Moreover, recombination of holes and electrons can occur in each material within the green emitting layer GEML (i.e., the hole transport matrix GHH, the electron transport matrix GEH, and the green dopant GD), thereby enhancing exciton formation and improving the recombination efficiency of holes and electrons.

[0091] refer to Figure 3A Typically, the first green dopant GD1 has a higher HOMO level than the hole transport matrix GHH (HOMO_GD1>HOMO_GHH). In this case, holes are trapped in the region with the higher HOMO level, causing them to be trapped in the first green dopant GD1 when injected from the hole transport layer into the green emitting layer. This hole trapping behavior results in the charging of holes in the first green dopant GD1 of the green emitting layer, making it difficult to completely discharge the carriers when switching from the on state to the off state (black state). Furthermore, when switching from the off state to a low grayscale state, the undischarged carriers remaining in the green emitting layer may lead to weak luminescence. Specifically, when multiple emitting layers of different colors are stacked, if hole trapping in the green emitting layer increases, an image defect of flickering green light immediately after switching from the off state (black state) to a low grayscale gray may be observed. Additionally, holes trapped in the first green dopant GD1 may reduce the efficiency of recombination with electrons in the green emitting layer. This leads to an increase in the driving voltage during conduction and a decrease in luminous efficiency.

[0092] The light-emitting device according to embodiments of this disclosure intends to address the aforementioned problem by using a green dopant having a HOMO energy level lower than that of the hole transport matrix GHH, in order to prevent hole trapping tendency in the green light-emitting layer. That is, referring to... Figure 3B The light-emitting device according to embodiments of this disclosure includes a green dopant GD having a HOMO level HOMO_GD lower than the HOMO_GHH level of the hole transport matrix GHH in the green light-emitting layer GEML. That is, the HOMO level of the hole transport matrix GHH in the green light-emitting layer GEML is designed to be higher than the HOMO level of the green dopant GD, such that when holes are transferred from the hole transport layer HTL to the green light-emitting layer GEML, the influence of the hole transport matrix GHH is greater than the influence of the green dopant GD. Therefore, when holes are transferred from the hole transport layer HTL to the green light-emitting layer GEML, hole trapping from the green light-emitting layer to the green dopant is prevented or reduced, and the holes are dispersed into the hole transport matrix GHH at a relatively high HOMO level, resulting in hole injection. The multi-channel hole transfer mediated by the hole transport matrix GHH along with the green dopant GD occurs, thus exhibiting or reducing the phenomenon of hole accumulation or buildup in a particular material.

[0093] Furthermore, both the green dopant GD and the first green dopant GD1 according to embodiments of this disclosure are iridium-based phosphorescent dopants. The green dopant GD according to embodiments of this disclosure is a phosphorescent dopant. The green dopant GD according to embodiments of this disclosure may include an iridium complex. The green dopant GD may include iridium as a core and electron-withdrawing groups, such as cyanide groups (-CN) or fluorine groups (-F), to increase low HOMO energy levels and mobility. For example, the phosphorescent dopant backbone may include an iridium compound, such as Ir(ppy). 3 (Tris(2-phenylpyridine)iridium(III)) (Ir(ppy)3(Tris(2-phenylpyridine)iridium(III))) or iridium(ppy) 2 (acac) (Ir(ppy)2(acac)). The green dopant GD according to embodiments of the present disclosure has high hole mobility and high electron mobility. Referring to the following figures, the hole mobility of the green dopant GD and the first green dopant GD1 according to embodiments of the present disclosure will be described in HOD (hole-only device) and the electron mobility will be described in EOD (electron-only device).

[0094] Figure 4A This is a graph illustrating the JV characteristics of the HOD device when the active layer includes the hole transport matrix GHH, the first green dopant GD1, and the green dopant GD according to embodiments of the present disclosure. Figure 4B This is a graph illustrating the JV characteristics of an EOD device when the active layer includes the electron transport matrix GEHA, the first green dopant GD1, and the green dopant GD, as described in the embodiments of this disclosure.

[0095] The electrical characteristics of holes in the active layer will be described in an HOD device that includes a hole injection layer, a first hole transport layer, an active layer, and a second hole transport layer between a first electrode and a second electrode.

[0096] like Figure 4A As shown, the current density characteristics with respect to the drive voltage exhibit similar trends when only the hole transport matrix GHH is included in the active layer of the HOD device and when the green dopant GD of the embodiments of this disclosure is included in the active layer of the HOD device. However, when Figure 3A When the first green dopant GD1 is included in the active layer of the HOD device, the current density is significantly reduced at the same driving voltage. That is, the hole mobility of the green dopant GD in the embodiments of this disclosure is greater than that of the first green dopant GD1.

[0097] The electronic properties related to the active layer will be described in an EOD device having a structure including a first electron injection layer, a first electron transport layer, an active layer, a second electron transport layer, and a second electron injection layer between a first electrode and a second electrode.

[0098] like Figure 4B As shown, the current density characteristics for the drive voltage exhibit similar trends when only the electron transport matrix GEHA is included in the active layer of the EOD device and when the green dopant GD of embodiments of this disclosure is included in the active layer of the EOD device. However, when Figure 3A When the first green dopant GD1 is included in the active layer of the EOD device, the current density is significantly reduced at the same driving voltage. That is, the electron mobility of the green dopant GD in the embodiments of this disclosure is greater than that of the first green dopant GD1.

[0099] from Figure 3A It can be seen that the first green dopant, GD1, not only has a higher HOMO energy level than the hole transport matrix GHH, but also has a very low hole mobility, such as... Figure 4A As shown, this results in a significant hole-trapping characteristic. For example... Figure 4B As shown, electron capture or scattering occurs. The current density of the first green dopant, GD1, is 10 mA / cm² only when the driving voltage is as high as 5 to 6 V. 2 Or even greater. Therefore, compared to the green dopant GD of this disclosure, the current of holes and electrons is delayed.

[0100] Therefore, it can be seen that the green dopant according to the embodiments of the present disclosure has a low HOMO energy level, a hole mobility similar to that of the hole transport matrix, and an electron mobility similar to that of the electron transport matrix.

[0101] In other words, when the green dopant according to the embodiments of this disclosure is included in the green light-emitting layer, the charge mobility increases, making rapid discharge of charge carriers in the green light-emitting layer possible when the light-emitting device is turned off, and also solving the problem of increased capacitance caused by charge carrier accumulation. Furthermore, when rapid discharge is completed in the green light-emitting layer in the off state, rapid charging is possible when switching to the on state, and thus the flickering phenomenon caused by residual charge carriers in the light-emitting device can be eliminated.

[0102] In the following, experimental examples 1 to 4 in which the green dopant and the electron transport matrix have different structures will be described, and the characteristic differences caused by the difference in HOMO energy levels between the green dopant and the electron transport matrix in the light-emitting device according to the embodiments of the present disclosure will be described.

[0103] Figures 5A to 5D These are band diagrams of experimental examples 1 to 4, which show different materials for the green dopant and electron transport matrix in the green emitting layer of the green emitting stack. Figure 6 The movement of charge carriers in the green light-emitting layer of the light-emitting device according to Experimental Example 1, comprising a hole transport matrix, a first electron transport matrix and a first green dopant, is shown. Figure 7 The illustration shows the movement of charge carriers from a green light-emitting layer comprising a hole transport matrix, an electron transport matrix, and a green dopant in a light-emitting device according to an embodiment of the present disclosure.

[0104] In the following experiments, the ratio of hole transport matrix GHH to electron transport matrix (GEH or GEHA) was set to 7:3.

[0105] Experimental Examples 1 to 4 all include the hole transport matrix GHH.

[0106] Figure 5A Experimental Example 1: The green emitting layer of EX1 includes a first green dopant GD1 (e.g., GD1) having a HOMO energy level higher than that of the hole transport matrix GHH. Figure 3A (as shown), and a first electron transport matrix GEHA having a HOMO level that is lower than that of the first green dopant GD1 but similar to that of the electron transport layer ETL of the adjacent green emitting layer.

[0107] Figure 5BExperimental Example 2 EX2's green emitting layer includes a first green dopant GD1 (e.g., GD1) having a HOMO energy level higher than that of the hole transport matrix GHH. Figure 3A (as shown), and has a HOMO level lower than that of the first green dopant GD1 but lower than... Figure 5A The first electron transport matrix GEHA has a HOMO level approximately 0.14 eV higher than the HOMO level of the electron transport dopant GEH (e.g., GEH). Figure 5B (As shown).

[0108] Figure 5C Experimental Example 3 EX3 includes a green dopant GD (e.g., with a HOMO energy level lower than that of the hole transport matrix GHH). Figure 3B As shown), and the first electron transport matrix GEHA (as shown) having a HOMO level that is lower than that of the green dopant GD but similar to that of the electron transport layer ETL adjacent to the green emitting layer. Figure 5C (As shown).

[0109] Figure 5D Experimental Example 4 EX4 includes a green dopant GD (e.g., with a HOMO energy level lower than that of the hole transport matrix GHH). Figure 3B (as shown), and has a HOMO level lower than that of green dopant GD but higher than... Figure 5A The first electron transport matrix GEHA has a HOMO level approximately 0.14 eV higher than the HOMO level of the electron transport dopant GEH (e.g., GEH). Figure 5D (As shown). Figure 5D Experimental Example 4 EX4 corresponds to the reference. Figures 1 to 2 and Figure 3B The light-emitting device described in the embodiments of this disclosure.

[0110] In the green emitting layers of Experiment Examples 1 to 4, hole transport matrix GHH, first green dopant GD1, green dopant GD, first electron transport matrix GEHA, and electron transport matrix GEH with the HOMO and LUMO energy level characteristics shown in Table 1 were used in the experiment.

[0111]

[0112] Referring to Table 1, Experimental Example 1 EX1 has a HOMO energy level difference of 0.57 eV between the first green dopant GD1 and the first electron transport matrix GEHA. Experimental Example 2 EX2 has a HOMO energy level difference of 0.43 V between the first green dopant GD1 and the electron transport matrix GEH. Experimental Example 3 EX3 has a HOMO energy level difference of 0.48 eV between the green dopant GD and the first electron transport matrix GEHA. Experimental Example 4 EX4 has a HOMO energy level difference of 0.34 eV between the green dopant GD and the electron transport matrix GEH.

[0113] When the first green dopant GD1 has a higher HOMO energy level than the hole transport matrix GHH, Experimental Example 1 EX1 and Experimental Example 2 EX2 have HOMO energy level differences when the HOMO energy levels of the electron transport matrix GEHA and GEH are different. And when the green dopant GD has a lower HOMO energy level than the hole transport matrix GHH, Experimental Example 3 EX3 and Experimental Example 4 EX4 have HOMO energy level differences when the HOMO energy levels of the electron transport matrix GEHA and GEH are different.

[0114] In Experiment 3 EX3 and Experiment 4 EX4, by introducing a green dopant with a low HOMO energy level, the number of holes trapped in the green dopant in the green light-emitting layer was reduced, and carrier behavior appeared under the condition that the hole transport matrix had a large influence. Furthermore, the hole transport matrix and the green dopant were used together as the hole transport medium, which improved the exciton generation efficiency.

[0115] like Figure 6 As shown, in Experimental Example 1 EX1, holes are directly injected into the first green dopant GD1 based on the HOMO energy level of the hole transport matrix, and electrons are directly injected into the first electron transport matrix based on the LUMO energy level of the first electron transport matrix.

[0116] The large HOMO energy difference between the hole transport matrix GHH and the first electron transport matrix GEHA (0.56 eV) restricts the movement of holes into the first electron transport matrix GEHA after they are injected into the first green dopant GD1. The LUMO energy difference between GHH and GEHA is also approximately 0.5 eV; therefore, electrons injected into the first electron transport matrix GEHA in the electron transport layer do not move to the hole transport matrix GHH, but are directly injected into the first green dopant GD1.

[0117] In Experiment 1 EX1, after holes and electrons were directly injected into the first green dopant GD1, the movement of holes and electrons from the first green dopant GD1 back to the hole transport matrix GHH or the first electron transport matrix GEHA was restricted due to the carrier trapping nature of the first green dopant GD1. This reduced the exciton generation efficiency in the green emitting layer and may therefore reduce the luminescence efficiency. Furthermore, when the holes and electrons trapped in the dopant do not form excitons but exist as residual carriers, complete discharge in the off state is difficult, and green light flickering occurs when switching from the off state to a low grayscale state.

[0118] like Figure 7 As shown, a light-emitting device according to an embodiment of the present disclosure (see [link]). Figure 5D Experimental Example 4) has a structure in which holes injected into the hole transport matrix GHH can easily move to the electron transport matrix GEH due to the small HOMO level difference between the two matrices, corresponding to 0.32 eV between the hole transport matrix and the electron transport matrix. In each green emitting layer of Experiments 1 to 4 EX1 to EX4, the hole transport matrix GHH and the electron transport matrices GEH are present in a content ratio of 7:3. Furthermore, the green emitting layer of Experimental Example 4 EX4 includes a green dopant GD with deep HOMO levels in a matrix mixture of the hole transport matrix GHH and the electron transport matrix GEH in a content ratio of 7:3.

[0119] When holes are injected into the green emitting layer using a green dopant GD with a low (deep) HOMO level, the holes transfer not only to the green dopant GD but also to the hole transport matrix GHH, which exists in a larger proportion. Furthermore, the difference in LUMO levels between the hole transport matrix GHH and the electron transport matrix GEH is less than 0.1 eV, allowing holes to easily move from the LUMO level of the electron transport matrix GEH to the LUMO level of the hole transport matrix GHH. Therefore, holes and electrons can transfer together in the high-content hole transport matrix GHH in the green emitting layer to generate excitons. These excitons generated in the hole transport matrix are then energy-transferred to the green dopant. Finally, the excitons in the green dopant fall into the ground state, thereby emitting green light.

[0120] Therefore, compared with Experimental Example 1 EX1 above, the light-emitting device according to the embodiments of this disclosure can improve the green light-emitting efficiency and minimize the residual charge carriers in the green light-emitting layer, thereby facilitating the formation of excitons through recombination of holes and electrons.

[0121] Figure 8 The graph shows the CV characteristics of the green light-emitting stacks in Experimental Examples 1 to 4. Figures 9A to 9C This is a graph showing the brightness of Experiments 2 to 4 when switching from a black state to a low grayscale state, compared to Experiment 1.

[0122] refer to Figure 8 When a voltage is applied, the area of ​​each CV graph in Experiments 1 to 4 EX1, EX2, EX3, and EX4 is proportional to the amount of charge carriers accumulated in the luminescent layer.

[0123] Experimental Example 1, EX1, has a first green dopant GD1 and a first electron transport matrix GEHA. The first green dopant GD1 has a higher HOMO level than the hole transport matrix GHH, while the first electron transport matrix GEHA has a lower HOMO level than the first green dopant GD1 but similar to the HOMO level of the electron transport layer ETL. Carrier charging occurs immediately after the applied voltage, and the area of ​​the CV graph is large. This means that when switching from the on state to the off state, a large number of carriers should be discharged in the green emitting layer, making it difficult to discharge completely or requiring a long time to discharge completely.

[0124] In Experiment 2 EX2, the electron transport matrix GEH has a wider band gap than the first electron transport matrix GEHA, but possesses a relatively higher HOMO level. Furthermore, the voset voltage, which changes in response to the applied voltage, is designed to be larger than in Experiment 1 EX1, thus mitigating the immediate carrier charging phenomenon that occurs after voltage application. Here, the electron transport matrix GEH exhibits partial energy transfer (EA), which possesses weak hole transport properties with bipolar or weak hole mobility. The GEH also exhibits relatively slower hole transport properties compared to the first electron transport matrix GEHA, thus delaying the charging of hole carriers in the green emitting layer. Additionally, the wide band gap of the electron transport matrix delays the injection of electrons from the electron transport layer to the green emitting layer, thereby delaying the charging of electron carriers in the green emitting layer. This carrier charging reduction and delay effect of the electron transport matrix GEH can also be obtained in Experiment 4 EX4.

[0125] Experimental Example 3 EX3 includes a first electron transport matrix GEHA, a green dopant GD, and the first electron transport matrix GEHA in the green emitting layer. Specifically, the green dopant GD has a HOMO level lower than that of the hole transport matrix GHH. In this case, holes are not trapped in the green dopant GD, but move through the hole transport matrix GHH, which is contained in large quantities in the green emitting layer, and can be used to form excitons in the hole transport matrix GHH, thereby preventing carrier accumulation in the emitting layer and enhancing the discharge effect when switching from the on state to the off state. The effect of the green dopant GD with this low HOMO level can also be achieved in Experimental Example 4 EX4.

[0126] That is, the light-emitting device according to the embodiments of this disclosure, such as Experimental Example 4 EX4, includes a green dopant GD, which has a HOMO level lower than the HOMO level of the hole transport matrix GHH, thereby providing a smooth discharge of charge carriers when switching from the on state to the off state. It also includes an electron transport matrix GEH, which has a LUMO level similar to the LUMO level of the hole transport matrix GHH and a HOMO level lower than the HOMO level of the green dopant GD, and therefore has a wide energy level, thereby solving the problem of flickering caused by charge carriers that are charged immediately after switching from the off state to the on state.

[0127] Table 2 below compares the green efficiency among Experiments 1 to 4 EX1, EX2, EX3, and EX4.

[0128]

[0129] As can be seen from Table 2, compared with Experimental Example 1 EX1, the green efficiency is significantly improved as the difference in HOMO energy levels between the green dopant and the electron transport matrix decreases.

[0130] Furthermore, it can be seen that the green efficiency is improved in all Experimental Examples 2 to 4 (EX2, EX3, EX4) compared to Experimental Example 1 EX1, but Experimental Example 4 EX4 shows a significant improvement in green efficiency. In particular, it can be seen that when the light-emitting device has the configuration of Experimental Example 4 EX4, the green efficiency of the light-emitting device according to the embodiments of this disclosure is improved.

[0131] In the following text, we will refer to Table 3 and Figures 9A to 9C The description is used to evaluate when each sub-pixel includes Figure 1 Experimental results on the brightness change when switching from a black state to a low grayscale state in a multi-stacked light-emitting device.

[0132] After maintaining a black state for 2 seconds (2000 milliseconds), the system switches to a low grayscale gray at a low current of 0.5 kilohertz and evaluates the change in brightness over time.

[0133]

[0134] like Figure 9A As shown, in Experiment 1 EX1, a peak in brightness appears immediately after switching from a black state to a low grayscale state, and then the brightness gradually decreases below the peak. The period during which the brightness remains constant after a predetermined time period is called the "average period". Referring to Table 3, the peak brightness of Experiment 1 EX1 corresponds to approximately 159% of the average brightness.

[0135] refer to Figure 9A In Experiment 2 EX2, a peak brightness appeared immediately after switching from a black state to a low grayscale state, and then the brightness gradually decreased below the peak brightness. A constant average brightness was maintained for a predetermined time period after the peak brightness appeared. (Reference) Figure 9A When comparing the average brightness of Experimental Example 1 EX1 with that of Experimental Example 2 EX2, the average brightness of Experimental Example 2 EX2 is larger. Referring to Table 3, the peak brightness of Experimental Example 2 EX2 corresponds to approximately 147% of the average brightness. Here, it can be seen that due to the wide bandgap of the electron transport matrix GEH and the reduced HOMO energy level difference with the green dopant, the scintillation level of Experimental Example 2 EX2 is reduced to less than 10%. However, in Experimental Example 2 EX2, the first green dopant GD1 has a higher HOMO energy level than the hole transport matrix GHH, and hole trapping occurs in the first green dopant GD1, thus scintillation cannot be avoided.

[0136] refer to Figure 9B In Experiment 3 EX3, a brightness peak appeared immediately after switching from a black state to a low grayscale state, and then the brightness gradually decreased below the peak. The average brightness was maintained for a predetermined time period after the peak brightness occurred. (Reference) Figure 9B When comparing the average brightness and peak brightness between Experimental Example 1 EX1 and Experimental Example 3 EX3, it can be seen that the average brightness of Experimental Example 3 EX3 is larger than that of Experimental Example 1 EX1, while the peak brightness is considerably smaller. Therefore, referring to Table 3, the peak brightness of Experimental Example 3 EX3 corresponds to approximately 116% of the average brightness. In Experimental Example 3 EX3, it can be seen that the use of the green dopant GD with a low HOMO energy level improves hole trapping to the green dopant GD.

[0137] from Figure 9CAs can be seen, in Experiment 4 EX4, after switching from a black state to a low grayscale state, a brightness peak does not appear immediately. When switching to the low grayscale state, the brightness gradually increases over time and then maintains a constant average saturation brightness. In this case, in Experiment 4 EX4 according to the embodiments of the present disclosure, the peak brightness appears within the average brightness range, the average brightness and the peak brightness are similar, and referring to Table 3, Experiment 4 EX4 shows a peak brightness of approximately 106% relative to the average brightness.

[0138] In other words, as shown in Experimental Example 4 EX4, the light-emitting device and light-emitting display device according to embodiments of this disclosure include a green dopant GD with a low HOMO energy level and an electron transport matrix GEH with a wide band gap but a relatively small difference in HOMO energy level from the green dopant GD in the green light-emitting layer, thereby preventing specific color brightness peaks and flickering after switching from a black state to a low grayscale state. This means that when holes are injected from the hole transport layer into the green light-emitting layer, multiple passes of the green dopant, hole transport matrix, and electron transport matrix are formed, thereby reducing carrier charging and preventing flickering before the conduction voltage between the first and second electrodes of the light-emitting device.

[0139] Materials contained in the green luminescent layer of embodiments of this disclosure will be described.

[0140] The green dopant GD and the first green dopant GD1 in the embodiments of this disclosure are iridium-based phosphorescent dopants with different substituents and different from each other in terms of HOMO energy level and hole mobility / electron mobility.

[0141] In other words, the green dopant GD in the embodiments of this disclosure further includes electron-withdrawing groups, such as cyanide groups (-CN) or fluorine groups (-F), in the iridium-based phosphorescent dopant, and therefore has a low HOMO level. The green dopant GD in the embodiments of this disclosure has a HOMO level that is approximately 0.09 eV lower than the HOMO level of the first green dopant GD1. In this case, although the difference in HOMO level between the green dopant GD and the first green dopant GD1 is not significant, there is a difference with the HOMO level of the hole transport matrix GHH, and as described above, the movement and function of holes when injected from the hole transport layer into the green emitting layer can vary considerably.

[0142] Furthermore, since the green dopant GD in the embodiments of this disclosure has a low HOMO energy level, therefore... Figure 4A As shown, the hole mobility is superior to that of the first green dopant GD1, and as... Figure 4B As shown, the electron mobility is also superior to that of the first green dopant, GD1.

[0143] Figure 10 This is a schematic diagram illustrating an electronic transport substrate according to an embodiment of the present disclosure.

[0144] like Figure 10 As shown, the electron transport matrix GEH can be formed by bonding the hole transport moiety EA on one side to the strong electron transport moiety EC on the other side via the linker EB between the two. Therefore, the electron transport matrix GEH contains a bipolar compound and is bipolar.

[0145] The linker EB can be, for example, an aromatic derivative having five or more carbon atoms.

[0146] Examples of hole transport modulo EAs can include carbazole derivatives, such as biscarbazole and indolecarbazole. To ensure the stability of the hole transport modulo EA, one of the hydrogen atoms in the hole transport modulo EA can be substituted with deuterium.

[0147] Examples of electron transport components (ECs) can include pyrimidines, pyrazines, pyridazines, triazines, etc., which contain two or more nitrogen atoms.

[0148] The electron transport matrix GEH has a LUMO level LUMO_GEH similar to the LUMO level of the hole transport matrix GHH and a HOMO level HOMO_GEH lower than the HOMO level of the green dopant GD, and therefore has a wide bandgap. To achieve this wide bandgap, the electron transport portion EC and the hole transport portion EA are tilted or twisted at a specific angle at their junction with the linker EB, thereby reducing the effective conjugation of the compounds used to form the electron transport matrix GEH.

[0149] Meanwhile, as the conjugation in the compounds that make up the material becomes shorter, the band gap of the material tends to widen.

[0150] Furthermore, compared to the first electron transport matrix GEHA, the electron transport matrix GEH of the embodiments of this disclosure has a wider band gap. However, the electron transport matrix GEH of the embodiments of this disclosure is twisted or tilted at the connection between the connector EB and the hole transport portion EA, resulting in a lower hole mobility compared to the relatively flat first electron transport matrix GEHA compound. The electron transport matrix GEH of the embodiments of this disclosure is twisted or tilted at the connection between the connector EB and the electron transport portion EC, resulting in a lower electron mobility compared to the relatively flat first electron transport matrix GEHA compound. Additionally, the electron transport matrix GEH of the embodiments of this disclosure comprises a compound in which the hole transport portion EA and the electron transport portion EC are linked to the connector EB, thereby possessing bipolarity.

[0151] The HOMO and LUMO levels described in this paper are evaluated based on the energy level of a vacuum of 0.0 eV. Both the HOMO and LUMO levels are below 0.0 eV and therefore have negative values. When comparing two materials, the deeper the energy level of a material, the lower the level on the energy map and the larger its absolute value.

[0152] Therefore, the HOMO level of the green dopant GD in the green emitting layer GEML of the embodiments of this disclosure is lower than the HOMO level of the first green dopant GD1, which has general hole trapping characteristics, and thus has a larger absolute value.

[0153] The HOMO level HOMO_GD of the green dopant GD is lower than the HOMO level HOMO_GHH of the hole transport matrix GHH, but higher than the HOMO level HOMO_GEH of the electron transport matrix GEH. <HOMO_GD<HOMO_GHH)。

[0154] In this scenario, when holes are transferred from the hole transport layer HTL adjacent to the green emitting layer GEML to the green emitting layer, the holes are not captured at the relatively low HOMO level of the green dopant GD. Instead, they are partitioned and moved to the hole transport matrix GHH and the green dopant GD of the green emitting layer GEML, thereby preventing hole charging from becoming severe in the emitting layer GEML.

[0155] Furthermore, in the embodiments of this disclosure, the electron transport matrix GEH in the green light-emitting layer GEML has a wide band gap, but has a higher HOMO energy level HOMO_GEH than the HOMO energy level HOMO_GEH1 of the electron transport matrix of a general green light-emitting layer (hereinafter referred to as the first electron transport matrix GEH1).

[0156] Figure 11 This is a cross-sectional view showing a light-emitting device according to another embodiment of the present disclosure.

[0157] like Figure 11 As shown, a light-emitting device according to another embodiment of the present disclosure includes a hole injection layer HIL, a hole transport layer HTL, a green light-emitting layer GEML, an electron transport layer ETL, and an electron injection layer EIL between a first electrode AND and a second electrode CAT.

[0158] Green luminescent layer GEML includes Figures 1 to 2 and Figure 3B The hole transport matrix GHH, electron transport matrix GEH, and green dopant GD are described in the paper.

[0159] Here, the green dopant GD has a HOMO level lower than that of the hole transport matrix GHH, and the electron transport matrix GEH has a LUMO level that differs from that of the hole transport matrix GHH by 0.15 eV or less, and has a wide bandgap with a HOMO level lower than that of the green dopant GD. Furthermore, the electron transport matrix GEH has a HOMO level 0.25 eV to 0.55 eV lower than that of the green dopant GD.

[0160] result, Figure 11 The light-emitting device has improved luminous efficiency of the green light-emitting layer, and due to the improved charging and discharging characteristics of the light-emitting device, it can prevent the flickering of green light when switching from the off state to the on state.

[0161] The following will describe an example of applying the above-described light-emitting device to a light-emitting display device.

[0162] Figure 12 This is a cross-sectional view showing a light-emitting display device according to an embodiment of the present disclosure.

[0163] like Figure 12 As shown, the light-emitting display device according to an embodiment of the present disclosure can be configured to... Figure 1 The light-emitting device is applied to at least one of multiple sub-pixels R_SP, G_SP, B_SP and W_SP, and emits light on the emitting side via a first electrode AND.

[0164] The light-emitting device (ED) of each sub-pixel may include a first electrode AND, a second electrode CAT, and an intermediate layer OS. The intermediate layer OS may include multiple stacks and have the same configuration in multiple sub-pixels R_SP, G_SP, B_SP, and W_SP. In addition, the intermediate layer OS may include an electron transport stack between the multiple stacks and the charge generation layer.

[0165] like Figure 12 As shown, the light-emitting display device according to an embodiment of the present disclosure may include a substrate 100 having a plurality of sub-pixels R_SP, G_SP, B_SP, W_SP, a light-emitting device ED generally disposed on the substrate 100, a thin-film transistor TFT disposed on each of the sub-pixels R_SP, G_SP, B_SP, W_SP and connected to a first electrode AND of the light-emitting device ED, and color filter layers 109R, 109G, 109B disposed below the first electrode AND of at least one sub-pixel.

[0166] Figure 12The example illustrates a case where a white subpixel W_SP is included in the light-emitting display device, but this disclosure is not limited thereto, and it is also possible to omit the white subpixel W_SP and provide only red, green, and blue subpixels R_SP, G_SP, and B_SP. In some cases, it is also possible to represent a combination of white cyan, magenta, and yellow subpixels by replacing the red, green, and blue subpixels.

[0167] The thin-film transistor (TFT) includes, for example, a gate electrode 102, a semiconductor layer 104, and a source electrode 106a and a drain electrode 106b connected to both sides of the semiconductor layer 104. Furthermore, a channel protection layer may be provided on the upper portion of the semiconductor layer 104 where the channel is located to prevent direct connection between the source electrode 106a / drain electrode 106b and the semiconductor layer 104. The TFT may include a buffer layer 101 on the substrate 100, and may be located on the buffer layer 101.

[0168] A gate insulating film 103 is disposed between the gate electrode 102 and the semiconductor layer 104.

[0169] The semiconductor layer 104 can be formed of, for example, oxide semiconductor, amorphous silicon, polycrystalline silicon, or a combination of two or more thereof. For example, when the semiconductor layer 104 is an oxide semiconductor, the heating temperature required to form the thin-film transistor can be reduced, allowing the substrate 100 to be used with a high degree of freedom, which is advantageous for application in flexible display devices.

[0170] The gate electrode 102 can be disposed on the gate insulating film 103, and the interlayer insulating film 105 can be further disposed between the gate electrode 102 and the source electrode 106a / drain electrode 106b.

[0171] Furthermore, the drain electrode 106b of the thin-film transistor TFT can be connected to the first electrode AND and the contact hole CT disposed in the first protective film 107 and the second protective film 108.

[0172] The first protective film 107 is mainly used to protect the thin-film transistor TFT, and color filters 109R, 109G, and 109B can be disposed on the first protective film 107.

[0173] The second protective film 108 is disposed on the first protective film 107, which includes color filters 109R, 109G, and 109B.

[0174] When multiple sub-pixels include red sub-pixel R_SP, green sub-pixel G_SP, blue sub-pixel B_SP, and white sub-pixel W_SP, such as Figure 12As shown, color filters are provided as first to third color filters 109R, 109G, and 109B for the remaining sub-pixels R_SP, G_SP, and B_SP, excluding the white sub-pixel W_SP, to allow white light emitted via the first electrode AND to pass through according to each wavelength. Furthermore, a second protective film 108 is formed below the first electrode AND to cover the first to third color filters 109R, 109G, and 109B. The first electrode AND is formed on the surface of the second protective film 108, excluding the contact hole CT, and is connected to one of the drain electrode 106b and source electrode 106a of the thin-film transistor TFT to receive electrical signals from the thin-film transistor TFT.

[0175] Here, the thin-film transistor array substrate 1000 may include a substrate 100, thin-film transistors (TFTs), color filters 109R, 109G, and 109B, as well as a first protective film 107 and a second protective film 108.

[0176] A light-emitting device ED is formed on a thin-film transistor array substrate 1000 including a partition 119 defining a light-emitting portion BH. The light-emitting device ED may include a transparent first electrode AND, a second electrode CAT facing the first electrode AND, and an intermediate layer OS formed between the first electrode AND and the second electrode CAT. It may also include multiple light-emitting stacks S1, S2, S3, and S4, first to third charge-generating layers CGL1, CGL2, and CGL3, and a green light-emitting layer GEML in at least one green light-emitting stack among the multiple light-emitting stacks S1, S2, S3, and S4 that emits green light. The green light-emitting layer GEML includes a hole transport matrix GHH, an electron transport matrix GEH, and a green dopant GD, such as... Figure 2 and Figure 3B As shown.

[0177] Here, the green dopant GD has a HOMO level lower than that of the hole transport matrix GHH, and the electron transport matrix GEH has a LUMO level that differs from that of the hole transport matrix GHH by 0.15 eV or less, and also has a wide bandgap with a HOMO level lower than that of the green dopant GD. Furthermore, the electron transport matrix GEH has a HOMO level 0.25 eV to 0.55 eV lower than that of the green dopant GD.

[0178] result, Figure 12 The light-emitting device ED has improved luminous efficiency of the green light-emitting layer, and due to the improved charging and discharging characteristics of the light-emitting device, it can prevent the flickering of green light when switching from the off state to the on state.

[0179] The first electrode AND is divided into each sub-pixel, and the remaining layers of the light-emitting device ED, excluding the first electrode AND, can be provided as a whole in the entire display area, rather than being distinguished by sub-pixels.

[0180] The first electrode AND or the second electrode CAT can be connected to a thin-film transistor (TFT).

[0181] Meanwhile, the above Figure 12 The light-emitting display device is shown as having a structure that emits light downwards, but this disclosure is not limited thereto. For example, the first electrode AND includes a reflective electrode, the second electrode CAT is a transparent electrode or a reflective transparent electrode, and a color filter is disposed above the second electrode CAT, so that the light-emitting display device can be applied in a top-emitting manner.

[0182] In the above structure, the intermediate OS of the light-emitting device ED is shared for each sub-pixel, but the light-emitting display device of the embodiments of this disclosure is not limited to this.

[0183] Figure 13 This is a cross-sectional view showing a light-emitting display device according to another embodiment of the present disclosure.

[0184] In addition, such as Figure 13 As shown, a light-emitting display device according to another embodiment of this disclosure may include a first electrode AND and a second electrode CAT facing each of the red sub-pixel R_SP, the green sub-pixel G_SP, and the blue sub-pixel B_SP, and a plurality of light-emitting stacks between the first electrode AND and the second electrode CAT, wherein the plurality of light-emitting stacks have overlapping light-emitting layers emitting the same color. That is, the red sub-pixel R_SP may have red light-emitting layers REML1 and REML2 in separate stacks, with a charge-generating layer CGL disposed between them; the green sub-pixel G_SP may have green light-emitting layers GEML1 and GEML2 in separate stacks, with a charge-generating layer CGL disposed between them; and the blue sub-pixel B_SP may have blue light-emitting layers BEML1 and BEML2 in separate stacks, with a charge-generating layer CGL disposed between them.

[0185] Here, a common layer CML11 related to hole injection and hole transport is provided between the first electrode AND and the first red light-emitting layer REML1, the first green light-emitting layer GEML1 and the first blue light-emitting layer BEML1, and a common layer CML21 related to electron transport is provided between the first red light-emitting layer REML1, the first green light-emitting layer GEML1 and the first blue light-emitting layer BEML1 and the charge generation layer CGL.

[0186] The charge generation layer CGL can be set by stacking an n-type charge generation layer NCGL and a p-type charge generation layer PCGL.

[0187] Furthermore, a common layer CML12 related to hole injection and hole transport can be provided between the charge generation layer CGL and the second red light-emitting layer REML2, the second green light-emitting layer GEML2 and the second blue light-emitting layer BEML2, and a common layer CML22 including an electron transport layer and an electron injection layer can be provided between the second red light-emitting layer REML2, the second green light-emitting layer GEML2 and the second blue light-emitting layer BEML2 and the second electrode CAT.

[0188] The common layers CML11 and CML12 associated with hole injection and transport may include at least one of a hole injection layer, a hole transport layer, and an electron blocking layer, and the common layers CML21 and CML22 associated with electron transport and injection may include at least one of a hole blocking layer, an electron transport layer, and an electron injection layer.

[0189] Here, as Figure 2 and Figure 3B As described, at least one of the green emitting layers GEML1 and GEML2 disposed in at least the green sub-pixel G_SP includes a hole transport matrix GHH, an electron transport matrix GEH, and a green dopant GD.

[0190] Here, the green dopant GD has a HOMO level lower than that of the hole transport matrix GHH, and the electron transport matrix GEH has a LUMO level that differs from that of the hole transport matrix GHH by 0.15 eV or less, and also has a wide bandgap with a HOMO level lower than that of the green dopant GD. Furthermore, the electron transport matrix GEH has a HOMO level 0.25 eV to 0.55 eV lower than that of the green dopant GD.

[0191] As a result, the green light-emitting device of the green sub-pixel G_SP can have improved luminous efficiency of the green light-emitting layer, and due to the improved charging and discharging characteristics, the green light-emitting device can prevent the flickering of green light when switching from the off state to the on state.

[0192] The light-emitting device and the light-emitting display device including the light-emitting device according to embodiments of the present disclosure have a green dopant GD in the green light-emitting layer. The green dopant GD has a HOMO energy level lower than the HOMO energy level of the hole transport matrix GHH, such that when holes are injected from the hole transport layer into the green light-emitting layer, multiple passes of the green dopant, the hole transport matrix and the electron transport matrix can be formed for hole movement.

[0193] Since holes or electrons are not trapped in the green dopant and contribute to exciton formation in each matrix and dopant, image quality degradation caused by residual charge carriers in the green light-emitting layer can be prevented.

[0194] The light-emitting device and the light-emitting display device including the light-emitting device contain a green dopant with a low HOMO energy level and an electron transport matrix with a small HOMO energy level difference from the green dopant in the green light-emitting layer, such that the onset voltage is higher than a predetermined level, the green layer has CV characteristics that promote the charging and discharging of charge carriers, and can prevent image quality degradation that occurs when the green light-emitting layer is turned on and off.

[0195] It can prevent or reduce the flickering of green emission spikes caused by residual charge carriers in the green emitting layer when switching from the off state to the low grayscale state.

[0196] The light-emitting display device according to the embodiments of the present disclosure and including the light-emitting device can improve the efficiency of the light-emitting layer and reduce image quality degradation, thereby achieving sustainable applicability and ESG (environmental / social / government) objectives.

[0197] A light-emitting device according to an embodiment of this disclosure may include a first electrode and a second electrode facing each other, and a green light-emitting stack comprising a hole transport layer, a green light-emitting layer, and an electron transport layer disposed between the first electrode and the second electrode. The green light-emitting layer may include a hole transport matrix, an electron transport matrix, and a green dopant. The HOMO level of the green dopant may be lower than the HOMO level of the hole transport matrix and may be higher than the HOMO level of the electron transport matrix. The HOMO level of the electron transport matrix may be higher than the HOMO level of the electron transport layer.

[0198] In a light-emitting display device according to an embodiment of the present disclosure, the HOMO energy level of the hole transport matrix may be lower than the HOMO energy level of the hole transport layer.

[0199] In a light-emitting display device according to one embodiment of the present disclosure, the HOMO level of the green dopant may differ from the HOMO level of the hole transport matrix by 0.15 eV or less.

[0200] In a light-emitting display device according to an embodiment of the present disclosure, the green dopant may be a phosphorescent dopant and may include iridium and electron-withdrawing groups.

[0201] In a light-emitting display device according to an embodiment of the present disclosure, the electron transport matrix may include a bipolar compound, wherein the electron transport portion and the hole transport portion are linked to a connector via a first connector and a second connector.

[0202] In a light-emitting display device according to one embodiment of the present disclosure, the HOMO level of the electron transport matrix can be 0.25 eV to 0.55 eV lower than the HOMO level of the green dopant.

[0203] In a light-emitting display device according to an embodiment of the present disclosure, among the materials included in the green light-emitting layer, the electron transport matrix has the widest band gap. The LUMO level of the electron transport matrix can be closer to the LUMO level of the hole transport matrix than the LUMO level of the electron transport layer. The HOMO level of the electron transport matrix can be closer to the HOMO level of the electron transport layer than the HOMO level of the green dopant.

[0204] In a light-emitting display device according to an embodiment of the present disclosure, a green dopant may be included in the green light-emitting layer in an amount of 5 wt% to 25 wt%.

[0205] In a light-emitting display device according to an embodiment of the present disclosure, the light-emitting device may further include: a red light-emitting stack including a red light-emitting layer disposed between the first electrode and the hole transport layer of the green light-emitting stack, a first charge-generating layer, a first blue light-emitting stack including a first blue light-emitting layer, a second charge-generating layer, and a third charge-generating layer and a second blue light-emitting stack including a second blue light-emitting layer disposed between the electron transport layer of the green light-emitting stack and the second electrode.

[0206] In a light-emitting display device according to an embodiment of the present disclosure, the green light-emitting layer may be thicker than the red light-emitting layer, the first blue light-emitting layer, and the second blue light-emitting layer.

[0207] In a light-emitting display device according to an embodiment of the present disclosure, the content of green dopant in the green light-emitting layer may be higher than the content of dopant in each of the red light-emitting layer, the first blue light-emitting layer, and the second blue light-emitting layer.

[0208] In a light-emitting display device according to an embodiment of the present disclosure, each of the first to third charge-generating layers may include an n-type charge-generating layer and a p-type charge-generating layer. The hole transport layer of the green light-emitting stack may contact the p-type charge-generating layer of the second charge-generating layer. The electron transport layer of the green light-emitting stack may contact the n-type charge-generating layer of the third charge-generating layer.

[0209] In a light-emitting display device according to an embodiment of the present disclosure, the second blue light-emitting layer may be thicker than the first blue light-emitting layer.

[0210] In a light-emitting display device according to an embodiment of the present disclosure, the content of green dopant in the green light-emitting layer may be higher than the content of dopant in each of the red light-emitting layer, the first blue light-emitting layer, and the second blue light-emitting layer.

[0211] In a light-emitting display device according to an embodiment of the present disclosure, two or more green light-emitting stacks, including a green light-emitting stack, may be stacked with a charge-generating layer disposed between them.

[0212] A light-emitting display device according to an embodiment of the present disclosure may include: a substrate comprising a plurality of sub-pixels, a pixel circuit at each of the plurality of sub-pixels, the pixel circuit including at least one transistor, and a light-emitting device connected to the pixel circuit at at least one of the plurality of sub-pixels.

[0213] The light-emitting device disclosed herein and the light-emitting display device including the light-emitting device have the following effects.

[0214] The light-emitting device and the light-emitting display device including the light-emitting device according to embodiments of the present disclosure have a green dopant GD having a HOMO level lower than the HOMO level of the hole transport matrix GHH in the green light-emitting layer, such that when holes are injected from the hole transport layer into the green light-emitting layer, multiple passes of the green dopant, the hole transport matrix and the electron transport matrix can be formed for hole movement.

[0215] Since holes or electrons are not trapped in the green dopant and contribute to exciton formation in each matrix and dopant, image quality degradation caused by residual charge carriers in the green light-emitting layer can be prevented.

[0216] The light-emitting device and the light-emitting display device including the light-emitting device include a green dopant with a low HOMO energy level and an electron transport matrix with a small HOMO energy level difference from the green dopant in the green light-emitting layer, such that the onset voltage is higher than a predetermined level, the green layer has CV characteristics that promote the charging and discharging of charge carriers, and can prevent image quality degradation that occurs when the green light-emitting layer is turned on and off.

[0217] It can prevent or reduce the flickering of green emission spikes when switching from the off state to a low grayscale state due to residual charge carriers in the green emitting layer.

[0218] The light-emitting device and the light-emitting display device including the light-emitting device according to the embodiments of the present disclosure can improve the efficiency of the light-emitting layer and reduce image quality degradation, thereby ensuring continued applicability and achieving ESG (environmental / social / government) objectives.

[0219] It will be apparent to those skilled in the art that various modifications and variations can be made to this disclosure without departing from its spirit or scope. Therefore, this disclosure is intended to cover such modifications and variations as long as they fall within the scope of the appended claims and their equivalents.

Claims

1. A light-emitting device, comprising: The first and second electrodes facing each other; as well as The green light-emitting stack includes a hole transport layer, a green light-emitting layer, and an electron transport layer disposed between the first electrode and the second electrode. The green light-emitting layer comprises a hole transport matrix, an electron transport matrix, and a green dopant. The HOMO level of the green dopant is lower than the HOMO level of the hole transport matrix and higher than the HOMO level of the electron transport matrix. The HOMO energy level of the electron transport matrix is ​​higher than that of the electron transport layer.

2. The light-emitting device according to claim 1, wherein, The HOMO energy level of the hole transport matrix is ​​lower than that of the hole transport layer.

3. The light-emitting device according to claim 1, wherein, The HOMO level of the green dopant differs from the HOMO level of the hole transport matrix by 0.15 eV or less.

4. The light-emitting device according to claim 1, wherein, The green dopant is a phosphorescent dopant and includes iridium and electron-withdrawing groups.

5. The light-emitting device according to claim 1, wherein the electron transport matrix comprises a bipolar compound, wherein the electron transport portion and the hole transport portion are linked to a connector via a first connector and a second connector.

6. The light-emitting device according to claim 1, wherein the HOMO level of the electron transport matrix is ​​0.25 eV to 0.55 eV lower than the HOMO level of the green dopant.

7. The light-emitting device according to claim 1, wherein, Of the materials contained in the green luminescent layer, the electron transport matrix has the widest band gap. The LUMO level of the electron transport matrix is ​​closer to the LUMO level of the hole transport matrix than the LUMO level of the electron transport layer, and The HOMO level of the electron transport matrix is ​​closer to the HOMO level of the electron transport layer than the HOMO level of the green dopant.

8. The light-emitting device according to claim 1, wherein, The green dopant is included in the green luminescent layer in an amount of 5 wt% to 25 wt%.

9. The light-emitting device according to claim 1, further comprising: A red light-emitting stack including a red light-emitting layer, a first charge-generating layer, a first blue light-emitting stack including a first blue light-emitting layer, and a second charge-generating layer are disposed between the first electrode and the hole transport layer of the green light-emitting stack; as well as A third charge generation layer and a second blue light-emitting stack comprising a second blue light-emitting layer are disposed between the electron transport layer and the second electrode in the green light-emitting stack.

10. The light-emitting device according to claim 9, wherein, The green light-emitting layer is thicker than the red light-emitting layer, the first blue light-emitting layer, and the second blue light-emitting layer.

11. The light-emitting device according to claim 9, wherein, The content of the green dopant in the green light-emitting layer is higher than the content of the dopant in each of the red light-emitting layer, the first blue light-emitting layer, and the second blue light-emitting layer.

12. The light-emitting device according to claim 9, wherein, Each of the first to third charge generation layers includes an n-type charge generation layer and a p-type charge generation layer. The hole transport layer of the green light-emitting stack contacts the p-type charge generation layer of the second charge generation layer, and The electron transport layer of the green light-emitting stack contacts the n-type charge generation layer of the third charge generation layer.

13. The light-emitting device according to claim 9, wherein, The second blue emitting layer is thicker than the first blue emitting layer.

14. The light-emitting device according to claim 1, wherein, Two or more green light-emitting stacks, including the green light-emitting stack, are stacked with a charge-generating layer disposed between them.

15. A light-emitting display device, comprising: A substrate comprising multiple sub-pixels; A pixel circuit at each of the plurality of sub-pixels, the pixel circuit comprising at least one transistor; as well as According to claim 1, the light-emitting device is connected to the pixel circuit at at least one of the plurality of sub-pixels.

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