Light emitting device and light emitting display apparatus including the same

Abstract

Disclosed are a light-emitting device and a light-emitting display apparatus including the same. The light-emitting device includes a first electrode and a second electrode facing each other, a light-emitting layer between the first electrode and the second electrode, a hole transport common layer between the first electrode and the light-emitting layer and an electron transport common layer between the light-emitting layer and the second electrode, a first hole transport auxiliary layer and a second hole transport auxiliary layer sequentially disposed between the hole transport common layer and the light-emitting layer, and an electron blocking layer between the second hole transport auxiliary layer and the light-emitting layer. A highest occupied molecular orbital (HOMO) level of the second hole transport auxiliary layer can be higher than a HOMO level of each of the first hole transport auxiliary layer and the electron blocking layer located on opposite sides of the second hole transport auxiliary layer, respectively.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2024-0179539, filed in Korea on December 5, 2024, which is incorporated herein by reference as if fully set forth herein. Technical Field

[0003] This disclosure relates to light-emitting devices, and more specifically, to light-emitting devices that have improved discharge characteristics and improved electroluminescence characteristics by changing the arrangement of the light-emitting layer in the light-emitting device, and to light-emitting display devices including the light-emitting device. Background Technology

[0004] In the present era, there is an increasing demand for various forms of display devices used to display information via images.

[0005] Currently developed light-emitting display devices include light-emitting devices that form pixels without requiring separate light source units, and such light-emitting devices have advantages in terms of thinness or flexibility and excellent color purity.

[0006] For example, such a light-emitting device includes two different electrodes and a light-emitting layer between the electrodes to emit light of different colors, thereby providing an image to convey information. Summary of the Invention

[0007] Therefore, this disclosure relates to light-emitting devices that substantially eliminate one or more problems caused by limitations and disadvantages of related technologies, and light-emitting display devices including such light-emitting devices.

[0008] The light-emitting display device displays an image by repeatedly turning the sub-pixels on and off.

[0009] The light-emitting display device has light-emitting devices in each sub-pixel, and emits light-emitting layers of different colors for the light-emitting devices to display different colors. In addition, the light-emitting devices also have separate functional layers together with the light-emitting layers to provide optical effects.

[0010] The light-emitting layer of a light-emitting device receives holes and electrons, and the holes and electrons recombine in the light-emitting layer to generate excitons for emitting light.

[0011] However, in structures with multiple functional layers to capture holes and electrons in the light-emitting layer of a light-emitting device, the following phenomenon occurs: the holes and electrons transferred to the light-emitting layer do not discharge to the two electrodes in the off state but are retained, resulting in light leakage.

[0012] The purpose of this disclosure is to provide a light-emitting device and a light-emitting display device including the light-emitting device, which prevents a trailing shadow phenomenon caused by a brightness delay before the off state due to discharge delay when switching to the off state, and improves electroluminescence characteristics.

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

[0014] In one embodiment of this disclosure, the light-emitting device is able to maintain the microcavity effect within the sub-pixel, while addressing low grayscale defects by changing the configuration of the optical compensation layer within the components of the light-emitting device disposed in the sub-pixel.

[0015] To achieve these and other advantages and according to the purposes of the invention, as embodied and broadly described herein, a light-emitting device includes: a first electrode and a second electrode facing each other; a light-emitting layer between the first electrode and the second electrode; a hole transport common layer between the first electrode and the light-emitting layer and an electron transport common layer between the light-emitting layer and the second electrode; a first hole transport auxiliary layer and a second hole transport auxiliary layer sequentially disposed between the hole transport common layer and the light-emitting layer; and an electron blocking layer between the second hole transport auxiliary layer and the light-emitting layer. The highest occupied molecular orbital (HOMO) energy level of the second hole transport auxiliary layer may be higher than the HOMO energy levels of each of the first hole transport auxiliary layer and the electron blocking layer located on either side of the second hole transport auxiliary layer.

[0016] In another aspect of this disclosure, a light-emitting display device includes: a substrate comprising green sub-pixels, red sub-pixels, and blue sub-pixels; a first electrode disposed in each of the green, red, and blue sub-pixels; a hole transport common layer disposed on the first electrode across the green, red, and blue sub-pixels; a green light-emitting layer, a red light-emitting layer, and a blue light-emitting layer disposed on the hole transport common layer at each of the green, red, and blue sub-pixels; a first hole transport auxiliary layer, a second hole transport auxiliary layer, and an electron blocking layer sequentially disposed between the hole transport common layer and the green light-emitting layer at the green sub-pixel; an electron transport common layer disposed on the green, red, and blue light-emitting layers across the green, red, and blue sub-pixels; and a second electrode on the electron transport common layer. The highest occupied molecular orbital (HOMO) energy level of the second hole transport auxiliary layer may be higher than the HOMO energy levels of each of the first hole transport auxiliary layer and the electron blocking layer located on either side of the second hole transport auxiliary layer.

[0017] It will be understood that both the foregoing general description of this disclosure and the following detailed description are exemplary and illustrative, and are intended to provide further explanation of the claimed invention. Attached Figure Description

[0018] The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings:

[0019] Figure 1 This is a schematic diagram illustrating a light-emitting display device according to one embodiment of the present disclosure;

[0020] Figure 2 This illustrates a setting according to one embodiment of the present disclosure. Figure 1 A cross-sectional view of the light-emitting device in a sub-pixel;

[0021] Figure 3 yes Figure 2 Energy band diagram of the light-emitting device;

[0022] Figure 4 This is a cross-sectional view showing the light-emitting device of a sub-pixel of a light-emitting display device according to one embodiment of the present disclosure;

[0023] Figure 5 It is shown Figure 4 A graph showing the JV characteristics of a green light-emitting device;

[0024] Figure 6 It is shown Figure 4A graph showing the CV characteristics of a green light-emitting device;

[0025] Figure 7 It is shown as Figure 4 A graph showing the brightness characteristics of a green light-emitting device as a function of its current density;

[0026] Figure 8 It is shown Figure 4 A curve showing the JV characteristics of the light-emitting device of the red sub-pixel;

[0027] Figure 9 It is shown Figure 4 A graph showing the CV characteristics of the light-emitting device of the red sub-pixel;

[0028] Figure 10 It is shown as Figure 4 A graph showing the brightness characteristics of the light-emitting device of the red sub-pixel as a function of the current density; and

[0029] Figure 11 This is a cross-sectional view showing a light-emitting display device according to one embodiment of the present disclosure. Detailed Implementation

[0030] The advantages and features of this disclosure, as well as methods for achieving said advantages and features, will become apparent from the exemplary embodiments described in detail herein and 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 assist those skilled in the art in fully understanding the scope of this disclosure. The scope of protection of this disclosure is defined by the claims and their equivalents.

[0031] In the following description of this disclosure, detailed descriptions of known steps, components, functions, techniques, and configurations may be omitted where such descriptions might unnecessarily obscure the focus of this disclosure. Furthermore, the names of components used in the following description are chosen for clarity of description and may differ from the names of components 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 will be understood that this disclosure can be practiced without these specific details. In other instances, known methods, procedures, components, and circuits have not been described in detail to avoid unnecessarily obscuring aspects of this disclosure.

[0032] The shapes, dimensions, ratios, angles, numbers, etc., of the various exemplary embodiments shown in the accompanying drawings for illustrating the present disclosure are given by way of example only. The present disclosure is not limited to the illustrations in the accompanying drawings.

[0033] In this specification, where terms such as “comprising,” “having,” “including,” etc. are used, one or more components may be added unless a term such as “only” is used. As used herein, the term “and / or” includes any and all of a single associated listed item and a combination of two or more associated listed items.

[0034] Expressions such as “at least one of” can modify the entire list of elements when placed before it, without needing to modify individual elements. The term “at least one” should be understood to include any and all combinations of one or more of the associated listed items. For example, “at least one of the first, second, and third elements” means all combinations of the three listed elements, combinations of any two of the three elements, and each individual element—the first, second, and third elements.

[0035] The terminology used herein is for describing specific aspects and is not intended to limit the scope of 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.

[0036] When interpreting components or values, components or values ​​should be interpreted to include a range of errors or tolerances, even if no explicit description of such a range of errors or tolerances is provided.

[0037] In describing various exemplary embodiments of this disclosure, when using terms such as "on," "above," "below," and "next to" to describe the positional relationship between two elements, at least one intermediate element may exist between the two elements unless "immediately adjacent," "directly," or "closely" is used. It should be understood that when an element or layer is referred to as "connected to" or "coupled to" another element or layer, that element or layer may be directly connected to or coupled to the other element or layer, or one or more intermediate elements or layers may exist.

[0038] 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 “just,” “immediately after,” or “directly” are used.

[0039] In describing 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, rather than to limit the components. Therefore, throughout the specification, a "first" component may be the same as a "second" component, unless otherwise specifically mentioned.

[0040] As will be fully understood by those skilled in the art, the features of the various embodiments of this disclosure may be coupled or combined with each other in part or in whole, and may interoperate with each other and be technically driven in a variety of ways. Embodiments of this disclosure may be performed independently of each other or may be performed together in an interdependent relationship.

[0041] As used herein, the term "doped" layer refers to a layer comprising a first material and a second material having physical properties different from those of the first material (e.g., n-type and p-type materials, or organic and inorganic materials). Besides the difference in properties, the first and second materials may also differ in their amounts within the doped layer. For example, the host material may be the dominant component, while the dopant material may be a minor component. The first material constitutes the majority of the weight of the doped layer. Based on the total weight of the first material in the doped layer, the second material may be added in an amount less than 30% by weight. Considering the weight ratio, a "doped" layer can be a layer used to distinguish the host material from the dopant material of a 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, then the layer is considered a "doped" layer when the n-type material is present in an amount less than 30% by weight, or when the p-type material is present in an amount less than 30% by weight.

[0042] 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 a layer is p-type and none of the materials constituting the layer is n-type. Similarly, a layer is considered "undoped" if at least one of the materials constituting a layer is organic and none of the materials constituting the layer is inorganic.

[0043] In this disclosure, an electroluminescence (EL) spectrum can be calculated by multiplying (a) a photoluminescence (PL) spectrum by (b) an external coupling or emission spectrum curve, wherein the photoluminescence (PL) spectrum applies the inherent properties of the emitting material, such as a dopant material or a host material, included in the organic emitting layer, and the external coupling or emission spectrum curve is determined by the structure and optical properties of the organic light-emitting element, including the thickness of the organic layer, such as, for example, an electron transport layer.

[0044] The term “can” fully encompasses all the meanings and scope of the term “may”.

[0045] 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 the elements in each of the drawings, similar reference numerals may refer to similar elements even though the same elements are shown in other drawings.

[0046] In the following, embodiments according to this disclosure will be described in detail with reference to the accompanying drawings.

[0047] Figure 1 This is a schematic diagram illustrating a light-emitting display device according to one embodiment of the present disclosure. All components of each light-emitting display device according to all embodiments of the present disclosure are operatively coupled and configured.

[0048] like Figure 1 As shown, the light-emitting display device 1000 according to an embodiment of the present disclosure includes a display panel 11, an image processor 12, a timing controller 13, a data driver 14, a scan driver 15, and a power supply device 16.

[0049] Display panel 11 displays images in response to data signals DATA supplied from data driver 14, scan signals supplied from scan driver 15, and power supplied from power supply device 16.

[0050] The display panel 11 may include sub-pixels SP disposed at each intersection of multiple gate lines GL and multiple data lines DL. The structure of the sub-pixels SP may vary depending on the type of the light-emitting display device 1000.

[0051] For example, subpixels (SPs) can be formed using a top-emitting method, a bottom-emitting method, or a dual-emitting method, depending on their structure. A subpixel SP is a unit that can emit light of its own color with or without a specific type of color filter. For example, a subpixel SP may include red subpixels, green subpixels, and blue subpixels. Alternatively, a subpixel SP may include, for example, red subpixels, blue subpixels, white subpixels, and green subpixels, but subpixels of other colors are also possible. A subpixel SP may have one or more different emitting portions depending on its light-emitting characteristics. For example, blue subpixels and subpixels emitting light of different colors may have different emitting portions.

[0052] One or more subpixels SP can constitute a unit pixel. For example, a unit pixel may include red subpixels, green subpixels, and blue subpixels, and these subpixels may be repeatedly arranged. Alternatively, a unit pixel may include red subpixels, green subpixels, blue subpixels, and white subpixels, and these subpixels may be repeatedly arranged, or they may be arranged in a quadrilateral. In embodiments according to this disclosure, the color type, arrangement type, arrangement order, etc., of the subpixels can be determined based on light-emitting characteristics, device lifetime, device specifications, etc., and are not limited thereto.

[0053] The display panel 11 can be divided into a display area (AA: within the dashed area) where subpixels SP are configured to display images and a non-display area NA surrounding the display area AA. A scan driver 15 can be installed in the non-display area NA of the display panel 11. Additionally, the non-display area NA may include pad portions PAD, which include pad electrodes PD.

[0054] Here, the display area AA is also referred to as the "active area", and the non-display area NA is also referred to as the "non-active area".

[0055] In addition to the externally supplied data signal DATA, the image processor 12 can also output a data enable signal DE. Besides the data enable signal DE, the image processor 12 can also output one or more of a vertical synchronization signal, a horizontal synchronization signal, and a clock signal, but these signals are omitted for the sake of description.

[0056] In addition to the drive signals from the image processor 12, the timing controller 13 can also receive data signals DATA. The drive signals may include a data enable signal DE. Additionally, the drive signals may include a vertical synchronization signal, a horizontal synchronization signal, and a clock signal. Based on the drive signals, the timing controller 13 outputs a data timing control signal DDC for controlling the operating timing of the data driver 14 and a gate timing control signal GDC for controlling the operating timing of the scan driver 15.

[0057] The data driver 14, in response to the data timing control signal DDC supplied from the timing controller 13, samples and latches the data signal DATA supplied from the timing controller 13, converts the data signal DATA into a gamma reference voltage, and outputs the gamma reference voltage.

[0058] Data driver 14 can output data signal DATA via data line DL. Data driver 14 can be provided as an integrated circuit IC. For example, data driver 14 can be electrically connected via a flexible circuit film to pad electrodes PD disposed in the non-display area NA of display panel 11.

[0059] The scan driver 15 can output a scan signal in response to the gate timing control signal GDC supplied from the timing controller 13. The scan driver 15 can output the scan signal through the gate line GL. The scan driver 15 can be implemented as an integrated circuit IC, or it can be implemented in the display panel 11 as an in-panel gate GIP.

[0060] The power supply device 16 can output high-potential voltage and low-potential voltage for driving the display panel 11. The power supply device 16 can supply high-potential voltage to the display panel 11 through a first power line EVDD (driving power line or pixel power line) and supply low-potential voltage to the display panel 11 through a second power line EVSS (auxiliary power line or common power line).

[0061] The display panel 11 is divided into a display area AA and a non-display area NA, and includes a plurality of sub-pixels SP defined by gate lines GL and data lines DL, which intersect each other in the display area AA to form a matrix.

[0062] Subpixels (SPs) may include emitting subpixels that emit at least two of the following colors: red, green, blue, yellow, magenta, and cyan. Additionally, subpixels (SPs) may emit their own color with or without a specific type of color filter, but this disclosure is not necessarily limited thereto. The color type, arrangement type, and arrangement order of the subpixel SPs can be determined based on luminescent characteristics, device lifetime, and device specifications.

[0063] Each of the subpixels SP can include a light-emitting portion and a non-light-emitting portion surrounding the light-emitting portion.

[0064] Figure 2 This illustrates a setting according to one embodiment of the present disclosure. Figure 1 A cross-sectional view of the light-emitting device in a sub-pixel. Figure 3 yes Figure 2 The energy band diagram of the light-emitting device.

[0065] like Figure 2 and Figure 3 As shown, a light-emitting device according to one embodiment of the present disclosure includes: a first electrode AND and a second electrode CAT facing each other; a light-emitting layer EML disposed between the first electrode AND and the second electrode CAT; a hole transport common layer CML1 disposed between the first electrode AND and the light-emitting layer EML; an electron transport common layer CML2 disposed between the light-emitting layer EML and the second electrode CAT; and a first hole transport auxiliary layer P1, a second hole transport auxiliary layer P2, and an electron blocking layer EBL sequentially disposed between the hole transport common layer CML1 and the light-emitting layer EML.

[0066] The first electrode AND can be the anode, and the second electrode CAT can be the cathode.

[0067] The first electrode AND can include, for example, a metallic material with high reflectivity or a transparent electrode. For example, the first electrode AND can be formed as a single-layer structure of a transparent conductive film such as ITO (indium tin oxide), IZO (indium zinc oxide), TO (tin oxide), or ITZO (indium tin zinc oxide); as a multilayer structure such as a stacked structure of aluminum (Al) and titanium (Ti) (Ti / Al / Ti), a stacked structure of aluminum (Al) and ITO (ITO / Al / ITO), an APC (Ag / Pd / Cu) alloy, a stacked structure of APC alloy and ITO (ITO / APC / ITO), a stacked structure of silver (Ag) and molybdenum / titanium alloy (Ag / MoTi); or as a single-layer structure comprising one material selected from silver (Ag), aluminum (Al), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba), or an alloy of two or more of these materials. However, embodiments of this disclosure are not limited thereto, and other materials may also be used. When the first electrode AND is formed of a single layer of transparent conductive film, light from the light-emitting device ED can be emitted through the first electrode AND. When the first electrode AND includes a reflective electrode, light can be emitted through the second electrode CAT facing the first electrode AND.

[0068] In a top-emitting light-emitting display device, the second electrode CAT may include a transparent electrode or a thin reflective transparent electrode that can transmit light, allowing light to pass through the second electrode CAT. The transparent electrode may be, for example, ITO or IZO, and the reflective transparent electrode may be formed of an alloy material selected from one or more of silver (Ag), aluminum (Al), molybdenum (Mo), gold (Au), magnesium (Mg), ytterbium (Yb), and strontium (Sr), but embodiments of this disclosure are not limited thereto, and other materials may also be used.

[0069] Alternatively, in a bottom-emitting light-emitting display device, the second electrode CAT may include a reflective electrode. For example, the reflective electrode may include an alloy of one or more of silver (Ag), aluminum (Al), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba), but is not limited to these examples. The second electrode CAT may be a transparent electrode. The second electrode CAT may include a transparent metallic material (TCO, transparent conductive material) such as ITO (indium tin oxide) or IZO (indium zinc oxide) that can transmit light, or a semi-transparent metallic material such as magnesium (Mg), silver (Ag), or an alloy of magnesium (Mg) and silver (Ag), but embodiments of this disclosure are not limited to these, and other materials may also be used. When the second electrode CAT includes a semi-transparent metallic material, the luminous efficiency can be improved through the microcavity effect. When the second electrode CAT includes a semi-transparent metallic material, its thickness is thin enough to allow light to pass through it.

[0070] The hole transport common layer CML1 is a layer in which holes are injected from the first electrode AND and transferred to the light-emitting layer EML, and may include multiple configurations. The hole transport common layer CML1 may include, for example, a hole injection layer HIL and a hole transport layer HTL, but embodiments of this disclosure are not limited thereto, and may also include other layers.

[0071] The hole injection layer HIL is in direct contact with the first electrode AND, which is a metal component serving as a reflective or transparent electrode, and functions to reduce the energy barrier at the interface with the first electrode AND. The hole injection layer HIL may comprise an inorganic material of metal fluoride to reduce the energy barrier at the interface with the first electrode AND. Alternatively, the hole injection layer HIL may comprise a p-type dopant in a hole transport organic material.

[0072] The hole transport layer (HTL) may include a hole transport material. For example, the hole transport material may include at least one of NPD (N,N-dinaphthyl-N,N'-diphenylbenzidine), TPD (N,N'-bis-(3-methylphenyl)-N,N'-bis-(phenyl)-benzidine), spiro-TAD (2,2',7,7′-tetra(N,N-diphenylamino)-9,9'-spirobisfluorene) or MTDATA (4,4',4"-tris(N-3-methylphenyl-N-phenylamino)-triphenylamine), but is not limited thereto.

[0073] An electron blocking layer (EBL) is used to prevent electrons from passing through the emitting layer (EML). For this function, the EBL comprises a material having a LUMO energy level higher than the lowest unoccupied molecular orbital (LUMO) energy level of the emitting layer. Additionally, the EBL prevents delays in hole transport between the hole transport layer (HTL) and the emitting layer (EML) and comprises a hole transport material with a large band gap.

[0074] The emissive layer (EML) consists of a host (H) and a dopant (D). Depending on the color of light emitted from the EML, the host H and the dopant D can have different compositions.

[0075] When the emissive layer (EML) includes a dopant D having an emission peak with a wavelength of 430 nm to 495 nm, the EML can emit blue light. The dopant D of the blue emissive layer can include a boron-based fluorescent dopant to improve efficiency and provide a predetermined lifetime.

[0076] When the emissive layer EML includes a dopant D having an emission peak with a wavelength of 500 nm to 595 nm, the emissive layer EML can emit green light. The dopant D of the green emissive layer may include an iridium-based phosphorescent dopant to provide a predetermined brightness.

[0077] When the emissive layer (EML) includes a dopant D having an emission peak with a wavelength of 600 nm to 650 nm, the EML can emit red light. The dopant D in the red emissive layer can include an iridium-based phosphorescent dopant to provide a predetermined brightness. The emission wavelength of the dopant D in the red emissive layer can be tuned to a longer wavelength by changing the substituents.

[0078] Dopant D has different materials depending on the emission wavelength, and therefore, the host material has a band gap and triplet energy levels to optimize the excitation of dopant D.

[0079] The electron transport common layer CML2 may include a hole blocking layer HBL, an electron transport layer ETL, and an electron injection layer EIL.

[0080] The hole blocking layer HBL is located on the opposite side of the electron blocking layer EBL, with the light emitting layer EML disposed therebetween and used to confine holes so that holes do not escape from the light emitting layer EML and to facilitate excitation.

[0081] The electron injection layer (EIL) is used to lower the energy barrier when electrons are injected from the second electrode (CAT) into the organic material. The EIL is formed with a relatively small thickness compared to the electron transport layer (ETL) and can comprise metallic and halogen materials such as alkali metals, alkaline earth metals, or transition metals.

[0082] An electron transport layer (ETL) is used to transfer electrons injected from the second electrode (CAT) into the electron injection layer (EIL) to the light-emitting layer (EML). The ETL may include at least one selected from, for example, the group consisting of: Alq3 (tris(8-hydroxyquinoline aluminum), PBD, TAZ, spiro-PBD, BAlq, Liq (lithium quinoline), BMB-3T, PF-6P, TPBI, COT, and SAlq, but this disclosure is not limited thereto.

[0083] A light-emitting device according to one embodiment of the present disclosure is characterized in that the hole transport auxiliary layer PL includes a first hole transport auxiliary layer P1 and a second hole transport auxiliary layer P2 formed of different materials. In embodiments of the present disclosure, the hole transport auxiliary layer PL may include three or more layers having at least one common material, but embodiments of the present disclosure are not limited thereto.

[0084] like Figure 3 As shown, the second hole transport auxiliary layer P2 is in contact with the first hole transport auxiliary layer P1 on one side and with the electron blocking layer EBL on the other side.

[0085] The highest occupied molecular orbital (HOMO) energy level of the second hole transport auxiliary layer P2 is higher than the HOMO energy levels of each of the first hole transport auxiliary layer P1 and the electron blocking layer EBL located on either side or opposite to the second hole transport auxiliary layer P2.

[0086] When holes flow from the emissive layer EML to the first electrode AND and discharge occurs in the off state, the second hole transport auxiliary layer P2 has a higher HOMO energy level than the adjacent layer, and therefore can temporarily and rapidly accumulate holes, thereby preventing the following phenomenon: holes are not retained at the interface between the emissive layer EML and the electron blocking layer EBL in the off state, and the charge retained at the interface between the emissive layer EML and the electron blocking layer EBL flows back to the emissive layer, which will lead to low grayscale light leakage even at low voltage.

[0087] Furthermore, the HOMO level of the second hole transport auxiliary layer P2 is higher than that of the HOMO level of the emitting layer. This is intended to allow holes to smoothly migrate to the side with the higher HOMO level during the off state.

[0088] The HOMO level of the second hole transport auxiliary layer P2 can have a difference of 0.25 eV or greater from the HOMO level of the electron blocking layer EBL in contact with the second hole transport auxiliary layer P2. The second hole transport auxiliary layer P2 can have a HOMO level that is significantly different from the HOMO level of the electron blocking layer EBL, and holes can also be rapidly migrated from the electron blocking layer EBL by the large surface potential GSP with the electron blocking layer EBL.

[0089] When the light-emitting device of a sub-pixel switches from an on state to an off state, holes retained in the light-emitting layer escape to the first electrode AND, and electrons escape to the second electrode CAT, resulting in discharge. However, when the holes and electrons released from the light-emitting layer EML do not pass through the adjacent layer but accumulate at the interface on both sides of the light-emitting layer, the discharge is delayed. In particular, holes or electrons retained at the interface adjacent to the light-emitting layer EML can be observed as weak light leakage. The light-emitting device according to an embodiment of the present disclosure has the following configuration: a second hole transport auxiliary layer P2 having a higher HOMO energy level than the adjacent layer is provided on one side of the electron blocking layer EBL to rapidly transfer holes from the electron blocking layer EBL adjacent to the light-emitting layer EML in the off state, so that the holes retained in the light-emitting layer EML during discharge smoothly pass through the electron blocking layer and accumulate in the second hole transport auxiliary layer P2. Therefore, the light-emitting device according to the embodiments of the present disclosure can improve the threshold voltage Vth of the electrostatic capacitance of the light-emitting device by providing a second hole transport layer P2 having a HOMO energy level that is relatively higher than the HOMO energy level of the electron blocking layer EBL, thereby preventing low grayscale leakage.

[0090] The second hole transport auxiliary layer P2 temporarily accumulates holes between the first hole transport auxiliary layer P1 and the electron blocking layer EBL, and serves as a trap layer. For this purpose, the second hole transport auxiliary layer P2 can have a smaller band gap than either the first hole transport auxiliary layer P1 or the electron blocking layer EBL. During the discharge process, the holes accumulated in the second hole transport auxiliary layer P2 escape towards the first electrode AND over time. Although the second hole transport auxiliary layer P2 temporarily accumulates holes, it is separated from the light-emitting layer EML via the electron blocking layer EBL disposed between the second hole transport auxiliary layer P2 and the light-emitting layer EML, and has a large HOMO energy level difference with the electron blocking layer EBL, thus acting as a large energy barrier to prevent holes retained in the first hole transport auxiliary layer P1 in the off state from passing to the electron blocking layer EBL.

[0091] By adjusting the thickness of the hole transport auxiliary layer PL, which includes a first hole transport auxiliary layer P1 and a second hole transport auxiliary layer P2, in the light-emitting device, the position of the light-emitting layer EML between the first electrode AND and the second electrode CAT can be controlled. Depending on the emitted light color, the total thickness of the hole transport auxiliary layer PL, which exhibits optimal microcavity effect, can vary.

[0092] The thickness of the first hole transport auxiliary layer P1 in the hole transport auxiliary layer PL can be proportional to the wavelength of the emitted light of each color.

[0093] For example, when the light-emitting device ED1 has a light-emitting layer EML that emits green light, the first hole transport auxiliary layer P1 can have a thickness proportional to any wavelength in the range of 500 nm to 595 nm, but the embodiments of this disclosure are not limited to this, and other wavelengths can also be used.

[0094] The first hole transport auxiliary layer P1 occupies the majority of the thickness of the hole transport auxiliary layer PL and is responsible for the main optical functions of the hole transport auxiliary layer PL. By adjusting the thickness of the first hole transport auxiliary layer P1, the vertical position of the light-emitting layer EML within the light-emitting device ED1 is adjusted, and thus the microcavity characteristics are controlled. The first hole transport auxiliary layer P1 has a refractive index of 2.0 or higher, thereby improving the microcavity characteristics and brightness-viewing angle characteristics.

[0095] The first hole transport auxiliary layer P1 has a higher hole mobility than the second hole transport auxiliary layer P2. Because of its higher hole mobility, the first hole transport auxiliary layer P1 smoothly transfers holes to the hole transport layer HTL and the light-emitting layer EML when the light-emitting device is turned on, thereby reducing the driving voltage.

[0096] The first hole transport auxiliary layer P1 can have a lower HOMO level than the adjacent second hole transport auxiliary layers P2 and HTL. Conversely, the HOMO level difference between the first hole transport auxiliary layer P1 and the second hole transport auxiliary layer P2 can be smaller than the HOMO level difference between the first hole transport auxiliary layer P1 and the hole transport layer HTL. The HOMO level difference between the first hole transport auxiliary layer P1 and the hole transport layer HTL can be less than approximately 0.15 eV. In some cases, the HOMO level of the first hole transport auxiliary layer P1 can be almost identical to the HOMO level of the hole transport layer HTL.

[0097] The second hole transport auxiliary layer P2 has a higher HOMO level than each of the hole transport layer HTL, the first hole transport auxiliary layer P1, and the electron blocking layer EBL associated with hole transport or hole transfer, and generates a large surface potential at the interface with the electron blocking layer EBL, and has the effect of reducing the capacitance of the light-emitting device.

[0098] The second hole transport auxiliary layer P2 has a higher HOMO energy level than the electron blocking layers EBL and the first hole transport auxiliary layer P1 on either side, and accumulates holes, which can be rapidly released between the emissive layer EML and the electron blocking layer EBL. Furthermore, the second hole transport auxiliary layer P2 increases the threshold voltage of the light-emitting device's capacitance and reduces low-grayscale efficiency. Therefore, the second hole transport auxiliary layer P2 can prevent low-grayscale leakage of the light-emitting device.

[0099] The second hole transport assist layer P2 can have a lower refractive index than the first hole transport assist layer P1. For example, the refractive index of the second hole transport assist layer P2 can be 2.0 or lower.

[0100] The second hole transport auxiliary layer P2, which is thinner than the first hole transport auxiliary layer P1, has a thickness of approximately 1 / 30 to 1 / 3 of the total thickness of the hole transport auxiliary layer PL. The second hole transport auxiliary layer P2 has a thickness of approximately 30 Å to 70 Å and accumulates holes during discharge in the off state, but does not cause hole transport delay when the light-emitting device is turned on when a predetermined level or higher voltage is applied.

[0101] When three or more hole transport auxiliary layers are disposed between the hole transport layer and the electron blocking layer, the hole transport auxiliary layer with the highest HOMO level among the three or more hole transport auxiliary layers can be adjacent to the electron blocking layer, but this is not required, and the hole transport auxiliary layer with the highest HOMO level among the three or more hole transport auxiliary layers can be interposed between the other two hole transport auxiliary layers. When three or more hole transport auxiliary layers are disposed between the hole transport layer and the electron blocking layer, the hole transport auxiliary layer with the smallest thickness among the three or more hole transport auxiliary layers can be positioned adjacent to the electron blocking layer EBL. When three or more hole transport auxiliary layers are disposed, the HOMO levels of the three or more hole transport auxiliary layers can be different, or at least two of the hole transport auxiliary layers can be the same or substantially the same.

[0102] Reference Figure 3In addition to the above description, the HOMO level of the hole transport layer HTL can be higher than the HOMO level of the first hole transport auxiliary layer P1, and the HOMO level of the first hole transport auxiliary layer P1 can be lower than the HOMO level of the second hole transport auxiliary layer P2, while the HOMO level of the second hole transport auxiliary layer P2 can be higher than the HOMO level of the electron blocking layer EBL. Furthermore, the HOMO level of the electron blocking layer EBL can be lower than the HOMO level of the emitting layer EML. Finally, the HOMO level of the emitting layer EML can be higher than the HOMO level of the hole blocking layer HBL, while the HOMO level of the hole blocking layer HBL can be approximately the same as the HOMO level of the electron transport layer ETL. However, this is not mandatory. In some embodiments, the HOMO levels of the emitting layer EML, the hole blocking layer HBL, and the electron transport layer ETL can be approximately the same as the HOMO level of the electron transport layer ETL. Figure 3 The implementation methods are different.

[0103] In embodiments of this disclosure, the HOMO level of the second hole transport auxiliary layer P2 can be the highest among the HOMO levels of the hole transport layer HTL, the first hole transport auxiliary layer P1, the second hole transport auxiliary layer P2, the electron blocking layer EBL, the light emitting layer EML, the hole blocking layer HBL, and the electron transport layer ETL. However, this is not necessary, and as long as the HOMO level of the second hole transport auxiliary layer P2 is higher than the HOMO levels of the first hole transport auxiliary layer P1 and the electron blocking layer EBL, one or more layers other than the first hole transport auxiliary layer P1 and the electron blocking layer EBL can have a HOMO level that is not lower than the HOMO level of the second hole transport auxiliary layer P2.

[0104] Further reference Figure 3 The LUMO level of the hole transport layer HTL can be lower than the LUMO level of the first hole transport auxiliary layer P1, and the LUMO level of the first hole transport auxiliary layer P1 can be higher than the LUMO level of the second hole transport auxiliary layer P2, while the LUMO level of the second hole transport auxiliary layer P2 can be higher than the LUMO level of the electron blocking layer EBL. Furthermore, the LUMO level of the electron blocking layer EBL can be higher than the LUMO level of the luminescent layer EML. Finally, the LUMO level of the luminescent layer EML can be lower than the LUMO level of the hole blocking layer HBL, while the LUMO level of the hole blocking layer HBL can be higher than the LUMO level of the electron transport layer ETL.

[0105] In embodiments of this disclosure, the LUMO level of the first hole transport auxiliary layer P1 can be the highest among the LUMO levels of the hole transport layer HTL, the first hole transport auxiliary layer P1, the second hole transport auxiliary layer P2, the electron blocking layer EBL, the light emitting layer EML, the hole blocking layer HBL, and the electron transport layer ETL. However, this is not necessary, and as long as the LUMO level of the light emitting layer EML is lower than the LUMO level of the other layers, one or more layers other than the light emitting layer EML can have a LUMO level higher than the LUMO level of the first hole transport auxiliary layer P1.

[0106] In addition, refer to Figure 3 The band gap of the hole transport layer HTL can be smaller than that of the first hole transport auxiliary layer P1, and the band gap of the first hole transport auxiliary layer P1 can be larger than that of the second hole transport auxiliary layer P2, while the band gap of the second hole transport auxiliary layer P2 can be smaller than that of the electron blocking layer EBL. Furthermore, the band gap of the electron blocking layer EBL can be larger than that of the emitting layer EML. Finally, the band gap of the emitting layer EML can be smaller than that of the hole blocking layer HBL, while the band gap of the hole blocking layer HBL can be larger than that of the electron transport layer ETL.

[0107] In embodiments of this disclosure, the band gap of the emissive layer EML can be the smallest among the band gaps of the hole transport layer HTL, the first hole transport auxiliary layer P1, the second hole transport auxiliary layer P2, the electron blocking layer EBL, the emissive layer EML, the hole blocking layer HBL, and the electron transport layer ETL. However, this is not necessary, and as long as the band gap of the emissive layer EML is smaller than the band gaps of the other layers, one or more layers other than the emissive layer EML can have band gaps different from those described above.

[0108] Meanwhile, the hole injection layer (HIL) and the electron injection layer (EIL) are in Figure 3 The hole injection layer (HIL) and electron injection layer (EIL) are very thin layers that are in contact with the first electrode (AND) and the second electrode (CAT), respectively. They are used to inject holes and electrons and do not act as an obstacle to the discharge of the light-emitting device.

[0109] At the same time, Figure 2 In the components of the light-emitting device ED1, the CPL on the second electrode CAT serves as a capping layer to improve the luminous efficiency of the light emitted from the light-emitting device and to protect the light-emitting device.

[0110] The capping layer CPL can include multiple layers with different refractive indices to improve the luminescence effect.

[0111] In the following, an embodiment of a light-emitting display device according to the present disclosure will be described.

[0112] Figure 4 This is a cross-sectional view showing the light-emitting device of a sub-pixel of a light-emitting display device according to one embodiment of the present disclosure.

[0113] like Figure 4 As shown, a light-emitting display device according to one embodiment of the present disclosure includes a red sub-pixel RSP, a green sub-pixel GSP, and a blue sub-pixel BSP. Since the resonant characteristics required for the emission of light of a certain color are different, the sub-pixels RSP, GSP, and BSP can have different stacking configurations.

[0114] Depending on the wavelength of the emitted light of a certain color, the light-emitting display device may include a hole transport auxiliary layer (RPL) or a hole transport auxiliary layer (GPL).

[0115] For example, within the visible light wavelength range, red has the longest wavelength and blue has the shortest. Therefore, the thickness of the red hole transport auxiliary layer RPL of the red sub-pixel RSP can be greater than the thickness of the green hole transport auxiliary layer GPL of the green sub-pixel GSP, but it is not limited to this.

[0116] Figure 4 The example shown has a configuration in which the blue subpixel BSP does not have a hole transport auxiliary layer, but embodiments of this disclosure are not limited thereto. For example, a blue hole transport auxiliary layer with a thickness smaller than the green hole transport auxiliary layer GPL of the green subpixel GSP can be provided in the blue subpixel.

[0117] The above example illustrates the following situation: the red emitting layer REML, the green emitting layer GEML, and the blue emitting layer BEML have the same vertical positions corresponding to the resonance condition in the same order; however, the implementation of this disclosure is not limited to this. For example, when the red emitting layer REML has a first order of vertical positions and the green emitting layer GEML has a second order of vertical positions, the green hole transport auxiliary layer GPL disposed in the green sub-pixel GSP can be thicker than the red hole transport auxiliary layer RPL disposed in the red sub-pixel RSP.

[0118] Specifically, according to Figure 4The light-emitting display device 1000 of the illustrated embodiment includes: a first electrode AND disposed in each of the red sub-pixel RSP, the green sub-pixel GSP, and the blue sub-pixel BSP; a hole transport common layer CML1 disposed on the first electrode AND across the red sub-pixel RSP, the green sub-pixel GSP, and the blue sub-pixel BSP; a red light-emitting layer REML, a green light-emitting layer GEML, and a blue light-emitting layer BEML disposed on the hole transport common layer CML1 across the red sub-pixel RSP, the green sub-pixel GSP, and the blue sub-pixel BSP; an electron transport common layer CML2 disposed on the red light-emitting layer REML, the green light-emitting layer GEML, and the blue light-emitting layer BEML across the red sub-pixel RSP, the green sub-pixel GSP, and the blue sub-pixel BSP; and a second electrode CAT disposed on the electron transport common layer CML2.

[0119] A capping layer CPL is applied to the second electrode CAT to enhance the light-emitting effect of the light-emitting devices RED, GED, or BED of each sub-pixel RSP, GSP, and BSP.

[0120] According to embodiments of the present disclosure, the light-emitting display device 1000 may include optional layers RFL, GFL, and BFL in each sub-pixel in addition to the hole transport common layer CML1 and the electron transport common layer CML2.

[0121] For example, the green optional layer GFL located at the green sub-pixel GSP may include a first hole transport auxiliary layer GPL1, a second hole transport auxiliary layer GPL2, an electron blocking layer EBL, and a green emitting layer GEML, which are sequentially disposed between the hole transport common layer CML1 and the electron transport common layer CML2.

[0122] The red optional layer RFL located at the red sub-pixel RSP may include a third hole transport auxiliary layer RPL1, a fourth hole transport auxiliary layer RPL2, an electron blocking layer EBL, and a red emitting layer REML, which are sequentially disposed between the hole transport common layer CML1 and the electron transport common layer CML2.

[0123] The optional blue layer BFL located at the blue sub-pixel BSP may include an electron blocking layer EBL and a blue emitting layer BEML sequentially disposed between the hole transport common layer CML1 and the electron transport common layer CML2.

[0124] In the example above, the red optional layer RFL, green optional layer GFL, and blue optional layer BFL all include a common electron blocking layer EBL. The electron blocking layer EBL can be shared across the red sub-pixel RSP, green sub-pixel GSP, and blue sub-pixel BSP, or it can be formed individually for each sub-pixel RSP, GSP, and BSP. When setting the electron blocking layer EBL for each sub-pixel RSP, GSP, or BSP, each of the sub-pixels RSP, GSP, or BSP can be patterned using the same deposition mask as the hole transport auxiliary layer below it or the emitting layer on it, thus reducing the number of deposition masks in the process.

[0125] exist Figure 4 In the example shown, a green hole transport auxiliary layer GPL, including a first hole transport auxiliary layer GPL1 and a second hole transport auxiliary layer GPL2, is set in the green sub-pixel GSP; a red hole transport auxiliary layer RPL, including a third hole transport auxiliary layer RPL1 and a fourth hole transport auxiliary layer RPL2, is set in the red sub-pixel RSP; and no hole transport auxiliary layer is set in the blue sub-pixel BSP.

[0126] However, the light-emitting display device according to the embodiments of this disclosure is not limited thereto. For example, a hole transport auxiliary layer may also be provided between the hole transport common layer CML1 and the electron blocking layer EBL in the blue sub-pixel BSP. The hole transport auxiliary layer provided in the blue sub-pixel BSP may have a smaller thickness than the hole transport auxiliary layers GPL and RPL provided in the green sub-pixel GSP and the red sub-pixel RSP. In some cases, when a hole transport auxiliary layer is provided in the blue sub-pixel BSP, the hole transport auxiliary layer may be formed of the same material as one of the first to fourth hole transport auxiliary layers GPL1, GPL2, RPL1, and RPL2 or have the same thickness as one of the first to fourth hole transport auxiliary layers GPL1, GPL2, RPL1, and RPL2.

[0127] A first hole transport auxiliary layer (GPL1) located at the green sub-pixel GSP is vertically positioned to ensure optimal resonance of the green emitting layer (GEML) at the green sub-pixel GSP between the first electrode AND and the second electrode CAT. Similarly, a third hole transport auxiliary layer (RPL1) located at the red sub-pixel RSP is vertically positioned to ensure optimal resonance of the red emitting layer (REML) at the red sub-pixel RSP between the first electrode AND and the second electrode CAT. The thicknesses of the first and third hole transport auxiliary layers GPL1 and RPL1 can be proportional to the green and red emission wavelengths, respectively. Furthermore, the thicknesses of the first and third hole transport auxiliary layers GPL1 and RPL1 are varied according to the color coordinates corresponding to the green and red emission wavelengths, respectively.

[0128] The thickness of the third hole transport auxiliary layer RPL1 can be greater than the thickness of the first hole transport auxiliary layer GPL1.

[0129] The second hole transport auxiliary layer GPL2 disposed in the green sub-pixel GSP can have a higher HOMO energy level than each of the first hole transport auxiliary layer GPL1 and the electron blocking layer EBL located on both sides or opposite sides of the second hole transport auxiliary layer GPL2.

[0130] Meanwhile, the first hole transport assist layer GPL1 can be provided by co-depositing the material of the second hole transport assist layer GPL2 with the material of the electron blocking layer EBL.

[0131] Compared to other color light-emitting devices, green light-emitting devices (GEDs) exhibit higher luminous efficiency and superior visibility. Therefore, the arrangement density of green light-emitting devices (GEDs) among red, green, and blue light-emitting devices in a light-emitting display device can be significantly increased. When a single-layer hole transport auxiliary layer is provided to correspond the color coordinates of green subpixels in a light-emitting display device—which has a difference in arrangement density between green and other color light-emitting devices—a significant green tint can be observed in the first frame response (FFR) driven by low grayscale.

[0132] The first frame response (FFR) of a light-emitting display device is related to various factors such as the arrangement of thin-film transistors and red, green, and blue subpixels, the driving method, and the compensation algorithm. Specifically, regarding the light-emitting devices, green light is significantly observed in the panel at low grayscale levels. This is because the capacitance of green light-emitting devices is larger than that of other color light-emitting devices.

[0133] The light-emitting display device according to embodiments of this disclosure includes a first hole transport auxiliary layer GPL1 and a second hole transport auxiliary layer GPL2 having a HOMO energy level difference in the structure of a green hole transport auxiliary layer GPL in a green sub-pixel GSP, thereby reducing the capacitance of the green light-emitting device. Therefore, the capacitance of the green light-emitting device can be adjusted in the initial state similarly to that of red and blue light-emitting devices, and specific colors are prevented from becoming overly prominent.

[0134] The light-emitting display device according to embodiments of the present disclosure, in addition to a first hole transport auxiliary layer GPL1 used for color coordinate adjustment in the hole transport auxiliary layer GPL in at least the green sub-pixel GSP, also includes a second hole transport auxiliary layer GPL2 having a higher HOMO energy level to assist hole discharge, thereby preventing low grayscale color deviation in green. Therefore, the light-emitting display device according to embodiments of the present disclosure can improve the discharge effect in low grayscale states or off states.

[0135] The proportion of green light-emitting devices greatly helps to represent white in light-emitting display devices. In the off state, holes at the interface between the light-emitting layer and the electron blocking layer in the green sub-pixel migrate quickly through the electron blocking layer EBL due to the large surface potential characteristics of the second hole transport auxiliary layer GPL2. Furthermore, the holes temporarily accumulate due to the high HOMO energy level of the second hole transport auxiliary layer GPL2, which effectively prevents leakage caused by residual holes at the interface of the light-emitting layer under low grayscale.

[0136] Furthermore, the light-emitting display device according to embodiments of this disclosure can ensure energy balance among the red, green, and blue light-emitting devices by reducing the initial capacitance of the green light-emitting device, which has high brightness efficiency. Additionally, the light-emitting display device can prevent defects in specific colors from being observed in the low grayscale state of the light-emitting display device.

[0137] at the same time, Figure 4 The structure has a configuration of a third hole transport auxiliary layer RPL1 and a fourth hole transport auxiliary layer RPL2 with a HOMO energy level difference in the red hole transport auxiliary layer RPL in the red sub-pixel RSP, thereby enhancing the discharge effect of the red light-emitting device in the off state and preventing light leakage in the low grayscale state.

[0138] The third hole transport auxiliary layer RPL1 adjusts the vertical position of the red emitting layer REML to correspond to the color coordinates of red, which are proportional to the red wavelength. The third hole transport auxiliary layer RPL1 can have a greater thickness than the first hole transport auxiliary layer GPL1 adjacent to it.

[0139] A fourth hole transport assist layer RPL2 is disposed between the third hole transport assist layer RPL1 and the electron blocking layer EBL to facilitate hole release. The fourth hole transport assist layer RPL2 may have a thinner thickness than the second hole transport assist layer GPL2.

[0140] Meanwhile, the third hole transport auxiliary layer RPL1 can also be prepared by co-depositing materials for the second hole transport auxiliary layer GPL2 and materials for the electron blocking layer EBL.

[0141] In the off state or low grayscale state, the second hole transport auxiliary layer GPL2 rapidly receives and accumulates holes from the green emitting layer GEML through the electron blocking layer EBL. Therefore, the second hole transport auxiliary layer GPL2 has a higher HOMO level than the electron blocking layer EBL, which is in direct contact with the second hole transport auxiliary layer GPL2, and also has a higher HOMO level than the adjacent green emitting layer GEML.

[0142] Similarly, the fourth hole transport auxiliary layer RPL2 rapidly receives and accumulates holes from the red emitting layer REML through the electron blocking layer in the off state or low grayscale state. For this reason, the fourth hole transport auxiliary layer RPL2 has a higher HOMO level than the adjacent electron blocking layer EBL and a higher HOMO level than the adjacent red emitting layer REML.

[0143] Furthermore, the green emitting layer has a green host GH and a green dopant GD, and the HOMO level of the green emitting layer depends on the HOMO of the green host, which is the dominant component. The red emitting layer has a red host RH and a red dopant RD, and the HOMO level of the red emitting layer depends on the HOMO of the red host, which is the dominant component.

[0144] The HOMO energy level of the red emitting layer is different from that of the green emitting layer. Therefore, the HOMO energy levels of the fourth hole transport auxiliary layer RPL2 and the second hole transport auxiliary layer GPL2, which have higher HOMO energy levels than either the red or green emitting layers, can also be different.

[0145] Meanwhile, the first hole transport auxiliary layer GPL1 may include, for example, any one of TAPC (1,1-bis[(di-4-tolylamino)phenyl]cyclohexane), NPB (N,N'-bis(1-naphthyl)-N'N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine), TCTA (tris(4-carbazolyl-9-ylphenyl)amine), or CBP (4,4'-bis(N-carbazolyl)-1,1'-biphenyl), but is not limited thereto.

[0146] The second hole transport assist layer GPL2 has optical properties similar to those of the first hole transport assist layer GPL1, but can include electron-donating groups in its compound structure to increase the HOMO energy level. The second hole transport assist layer GPL2 can be formed from compounds comprising units of a hole transport material that is the same as or similar to the hole transport material in the first hole transport assist layer GPL1 and electron-donating groups.

[0147] For example, the electron-donating group can be triphenylamine, carbazole, fluorine, thiophene, methoxy (-OCH3), alkyl, etc., but is not limited to these.

[0148] As another example, the first hole transport assist layer GPL1 may also contain electron-withdrawing groups in the compound to lower the HOMO energy level, thereby increasing the HOMO energy level difference with the second hole transport assist layer GPL2.

[0149] Examples of electron-withdrawing groups include, but are not limited to, cyano (-CN), trifluoromethyl (-CF3), pyridine, oxadiazole, triazine, benzothiadiazole, etc.

[0150] Additionally, examples of the third hole transport auxiliary layer RPL1 may include, but are not limited to, TCTA (tris(4-carbazolyl-9-ylphenyl)amine), CBP (4,4'-bis(N-carbazolyl)-1,1'-biphenyl), NPD (N,N-di(1-naphthyl)-N,N'-diphenylbenzidine), FLU-DTPA (N1-(9,9-diphenyl-9H-fluorene-2-yl)-N1-(4-(diphenylamino)phenyl)-N4,N4-diphenylphenyl-1,4-diamine), and FLU-DCAR (N,N-bis(4-(9H-carbazolyl-9-yl)phenyl)-9,9-diphenyl-9H-fluorene-2-amine).

[0151] The fourth hole transport auxiliary layer RPL2 has similar optical properties to the third hole transport auxiliary layer RPL1, but can include electron-donating groups in the compound structure to increase the HOMO energy level. The fourth hole transport auxiliary layer RPL2 can be formed from compounds comprising units of hole transport materials the same as or similar to those in the third hole transport auxiliary layer RPL1 and electron-donating groups.

[0152] However, the embodiments of this disclosure are not limited thereto. The materials can be changed, as long as the HOMO energy level relationships of the hole transport layer, the first hole transport auxiliary layer GPL1 and the second hole transport auxiliary layer GPL2, the electron blocking layer and the green emitting layer GEML satisfy the above requirements.

[0153] The effects of using the structures of several hole transport layers based on this disclosure will be described experimentally below.

[0154] First, experimental examples (EX1) describing the use of a green hole transport auxiliary layer GPL as a single optical compensation layer, and experimental examples 2 and 3 (EX2 and EX3) describing the use of a laminate of a first hole transport auxiliary layer GPL1 and a second hole transport auxiliary layer GPL2 as a single optical compensation layer.

[0155] Figure 5 It is shown Figure 4 The curve of JV characteristics of green light-emitting devices. Figure 6 It is shown Figure 4 A graph showing the CV characteristics of a green light-emitting device. Figure 7 It shows that it depends on Figure 4 A graph showing the brightness characteristics of the current density of a green light-emitting device.

[0156] Table 1 shows the HOMO level, LUMO level, triplet level T, and band gap Eg of the hole transport layer HTL, the first hole transport auxiliary layer GPL1, the second hole transport auxiliary layer GPL2, the electron blocking layer EBL, the green dopant GD of the green light-emitting layer, and the green host GH of the green light-emitting layer in the green light-emitting device used in the experimental example.

[0157] [Table 1]

[0158]

[0159] In a green light-emitting device (GED), the first hole transport assist layer (GPL1) has a HOMO energy difference of 0.15 eV or less with the adjacent hole transport layer (HTL) and has a higher hole mobility than the second hole transport assist layer (GPL2). The first hole transport assist layer (GPL1) has a thickness T1 suitable for the color coordinate characteristics of the green light-emitting device. For example, the thickness of the first hole transport assist layer (GPL1) is 200 Å to 700 Å, but is not limited to this.

[0160] The second hole transport assist layer GPL2 has a HOMO energy level higher than -5.3 eV, and the absolute value of the HOMO energy level is 5.3 eV or less. The second hole transport assist layer GPL2 has a HOMO energy level difference of 0.25 eV or greater with the adjacent electron blocking layer EBL. The second hole transport assist layer GPL2 can facilitate hole discharge in the off state or low grayscale state, and can have a thickness of 1 / 30 to 1 / 3 of the thickness of the first hole transport assist layer GPL1. Preferably, the thickness of the second hole transport assist layer GPL2 can be 30 Å to 70 Å.

[0161] [Table 2]

[0162]

[0163] Experimental Examples 1 to 3 (EX1, EX2 and EX3) include materials having the physical properties of the hole transport layer, the first hole transport auxiliary layer and the second hole transport auxiliary layer, the electron blocking layer and the green luminescent layer as shown in Table 1.

[0164] In Experimental Example 1 (EX1), the green hole transport auxiliary layer GPL is a single first hole transport auxiliary layer GPL1 with a thickness of T1.

[0165] In Experimental Examples 2 and 3 (EX2 and EX3), the hole transport auxiliary layer is formed as a laminated structure of a first hole transport auxiliary layer GPL1 and a second hole transport auxiliary layer GPL2, but the thickness of the second hole transport auxiliary layer GPL2 is changed to 30 Å and 50 Å, respectively.

[0166] As shown in Table 2 and Figure 5 As can be seen from the JV curves, compared to Experimental Example 1 (EX1), the voltage used to provide the same current density gradually increases in Experimental Examples 2 and 3 (EX2 and EX3). This means that the threshold voltage used to obtain the predetermined current density in Experimental Examples 2 and 3 (EX2 and EX3) is higher than the threshold voltage in Experimental Example 1 (EX1), and leakage is reduced or prevented in the low grayscale state.

[0167] As from Figure 6 The CV curves show that, compared to Experimental Example 1 (EX1), the driving voltages that induce the predetermined change in capacitance are higher in Experimental Examples 2 and 3 (EX2 and EX3). This means that the light-emitting devices in Experimental Examples 2 and 3 (EX2 and EX3) ensure an initial capacitance level of the predetermined level or higher, and therefore there is no leakage in the low grayscale state or the off state.

[0168] As from Figure 7 The graph showing efficiency as a function of current density shows that experimental examples 2 and 3 (EX2 and EX3) achieve efficiency at 0.00001 mA / cm². 2 Up to 0.0001 mA / cm 2 It exhibits low brightness at low grayscale current density.

[0169] Table 2 shows the results at 10 mA / cm². 2 The efficiency (Eff (%)) compared to Experimental Example 1 (EX1) at the current density, which means that the efficiency of Experimental Examples 2 and 3 (EX2 and EX3) at the current density (10 mA / cm²) during normal operation is comparable. 2 The actual increase is below.

[0170] Additionally, the indicator module performance FFR is the color coordinate change of Experimental Examples 2 and 3 (EX2 and EX3) compared to Experimental Example 1 (EX1). As this value increases, low grayscale efficiency decreases.

[0171] Furthermore, as can be seen from Table 2, Experimental Example 1 (EX1) and Experimental Example 3 (EX3) exhibit similar light-emitting device lifetimes (LT (%)). Compared to Experimental Example 1 (EX1), Experimental Example 2 (EX2) has a reduced lifetime, but it has the effect of relatively increasing the threshold voltage of the light-emitting device, increasing the efficiency during operation, and reducing the low grayscale efficiency, thus it is superior to Experimental Example 1 (EX1) in terms of optical characteristics.

[0172] The results of Experimental Example 3 (EX3) in Table 2 show that, in the embodiments of this disclosure, when the thickness of the second hole transport auxiliary layer GPL2 is 50 Å or greater, the effects of preventing low grayscale light leakage, stabilizing driving characteristics, and providing effective discharge in the off state are achieved.

[0173] In the following, the effects of the experimental example will be described by changing the material used for the second hole transport auxiliary layer or the material used for the electron blocking layer in the structure of the green light-emitting device, compared with the structure of Experimental Example 3 (EX3) according to the embodiments of this disclosure.

[0174] [Table 3]

[0175]

[0176] Compared to Experimental Example 3 (EX3), in Experiments 4 and 5 (EX4 and EX5), the HOMO levels of the materials used for the second hole transport auxiliary layer GPL2A or GPL2B are lower than -5.3 eV. The HOMO level of the second hole transport auxiliary layer material GPL2A in Experimental Example 4 (EX4) is closer to the HOMO level of the electron blocking layer EBL than the HOMO level of the second hole transport auxiliary layer material GPL2B in Experimental Example 5 (EX5).

[0177] In Experimental Example 6 (EX6), the second hole transport assist layer GPL2 was formed using the same material as in Experimental Example 3 (EX3), but the electron blocking layer material adjacent to the second hole transport assist layer GPL2 was different, and the HOMO energy level between the electron blocking layer and the second hole transport assist layer GPL2 was set to 0.25 eV or less.

[0178] Based on the variations in Experimental Examples 3 to 6 (EX3, EX4, EX5, and EX6), Experimental Example 3 (EX3) exhibits the best effect in reducing low grayscale efficiency. Specifically, it was found that when the green light-emitting device in the light-emitting display device according to the embodiments of this disclosure is applied to Experimental Example 3 (EX3), the threshold voltage of the green light-emitting device increases, the efficiency during operation improves, and the lifespan remains stable. Furthermore, the phenomenon of green prominence can be prevented by reducing the efficiency of green at low grayscale. Additionally, the discharge effect in the off state can be improved.

[0179] In the following sections, experimental example 7 (EX7) in which the red hole transport auxiliary layer RPL of the red light-emitting device is used as a single optical compensation layer, and experimental examples 8 and 9 (EX8 and EX9) in which the third hole transport auxiliary layer RPL1 and the fourth hole transport auxiliary layer RPL2 are laminated, will be described.

[0180] Figure 8 It is shown Figure 4 A graph showing the JV characteristics of the light-emitting device of the red subpixel. Figure 9 It is shown Figure 4 A graph showing the CV characteristics of the light-emitting device of the red sub-pixel. Figure 10 It is shown as Figure 4 A graph showing the brightness characteristics of the light-emitting device of the red sub-pixel as a function of the current density.

[0181] Table 4 shows the HOMO level, LUMO level, triplet level T, and band gap Eg of the hole transport layer HTL, the third hole transport auxiliary layer RPL1, the fourth hole transport auxiliary layer RPL2, the electron blocking layer EBL, the red dopant RD of the red emitting layer, and the red host RH of the red emitting layer in the red emitting devices used in Experimental Examples 7 to 9 (EX7, EX8, and EX9).

[0182] [Table 4]

[0183]

[0184] In a red light-emitting device (RED), the third hole transport auxiliary layer RPL1 has a HOMO energy level difference of 0.15 eV or less with the adjacent hole transport layer HTL, and has a higher hole mobility than the fourth hole transport auxiliary layer RPL2.

[0185] The third hole transport auxiliary layer RPL1 has a thickness T2 suitable for the color coordinate characteristics of a red light-emitting device. For example, the thickness of the third hole transport auxiliary layer RPL1 is 200 Å to 1200 Å, but is not limited to this.

[0186] The fourth hole transport assist layer RPL2 has a HOMO level higher than -5.6 eV, and the absolute value of the HOMO level is 5.6 eV or less. The fourth hole transport assist layer RPL2 has a HOMO level difference of 0.15 eV or greater with the adjacent electron blocking layer EBL. The fourth hole transport assist layer RPL2 facilitates hole discharge in the off state or low-level state, and its thickness can be 1 / 30 to 1 / 3 of the thickness of the third hole transport assist layer RPL1. Preferably, the thickness of the fourth hole transport assist layer RPL2 can be 30 Å to 50 Å.

[0187] [Table 5]

[0188]

[0189] Experimental Examples 7 to 9 (EX7, EX8 and EX9) include materials having the physical properties of the hole transport layer, the third hole transport auxiliary layer and the fourth hole transport auxiliary layer, the electron blocking layer and the red emitting layer as shown in Table 4.

[0190] In Experimental Example 7 (EX7), the red hole transport auxiliary layer RPL is formed as a single third hole transport auxiliary layer RPL1 with a thickness of T2.

[0191] In Experimental Examples 8 and 9 (EX8 and EX9), the hole transport auxiliary layer was formed as a laminated structure of a third hole transport auxiliary layer RPL1 and a fourth hole transport auxiliary layer RPL2, but the thickness of the fourth hole transport auxiliary layer RPL2 was changed to 30 Å and 50 Å, respectively.

[0192] As shown in Table 5 and Figure 8 The JV curves show that, compared to Experimental Example 7 (EX7), the voltage used to provide the same current density gradually increases in Experimental Examples 8 and 9 (EX8 and EX9). This means that the threshold voltage used to provide a predetermined current density or higher in Experimental Examples 8 and 9 (EX8 and EX9) is higher than the threshold voltage in Experimental Example 7 (EX7), and leakage is reduced or prevented in the low grayscale state.

[0193] As from Figure 9 The CV curves show that, compared to Experimental Example 7 (EX7), the driving voltages that cause a predetermined or greater change in capacitance are relatively higher in Experimental Examples 8 and 9 (EX8 and EX9). This means that the light-emitting devices in Experimental Examples 8 and 9 (EX8 and EX9) ensure an initial capacitance of or higher, and therefore there is no leakage in the low grayscale state or the off state.

[0194] As from Figure 10The graph showing the efficiency as a function of current density shows that, in experimental examples 8 and 9 (EX8 and EX9), at 0.0001 mA / cm², 2 up to 0.001 mA / cm 2 The brightness decreases at low grayscale current densities.

[0195] Table 5 shows the results at 10 mA / cm². 2 The efficiency (Eff (%)) at the current density compared to Experimental Example 7 (EX7) is shown, and Experimental Examples 8 and 9 (EX8 and EX9) actually have higher efficiency at the current density (10 mA / cm2) during normal operation.

[0196] Furthermore, the indicator module performance FFR is expressed in color coordinates (CIE), and the value for Experimental Example 7 (EX7) is lower than that for each of Experimental Examples 8 and 9 (EX8 and EX9). As this value increases, low-grayscale efficiency decreases. It can be seen that Experimental Example 8 (EX8) exhibits better FFR characteristics compared to Experimental Example 9 (EX9).

[0197] It can be seen that when the green light-emitting device and the red light-emitting device are placed next to each other, Experimental Example 3 (EX3) for the green light-emitting device and Experimental Example 8 (EX8) for the red light-emitting device exhibit similar FFR values.

[0198] For example, the thickness of the second hole transport assist layer GPL2 in a green light-emitting device can differ from the thickness of the fourth hole transport assist layer RPL2 in a red light-emitting device. By adjusting the thickness of the second hole transport assist layer GPL2 to be greater than the thickness of the fourth hole transport assist layer RPL2, a balance can be achieved between the low grayscale efficiency of the red subpixel and the low grayscale efficiency of the green subpixel.

[0199] In addition, as can be seen from Table 5, Experimental Example 7 (EX7) exhibits a similar light-emitting device lifetime (LT (%)) to Experimental Example 8 (EX8), and Experimental Example 9 (EX9) exhibits an improved light-emitting device lifetime (LT (%)) compared to Experimental Example 7 (EX7) and Experimental Example 8 (EX8).

[0200] The results of Experiment Examples 8 and 9 (EX8 and EX9) in Table 5 show that, in embodiments of this disclosure, when the thickness of the fourth hole transport auxiliary layer RPL2 is 30 Å to 50 Å, the effects of preventing low grayscale light leakage, stabilizing driving characteristics, and providing effective discharge in the off state are achieved.

[0201] The light-emitting device and light-emitting display apparatus according to embodiments of the present disclosure can prevent low-grayscale light leakage due to the increase in potential of the first electrode caused by residual charge between the electron blocking layer and the light-emitting layer in at least the green sub-pixel.

[0202] At least one hole transport auxiliary layer of the green subpixel is formed as a stacked structure of a first hole transport auxiliary layer and a second hole transport auxiliary layer with different HOMO energy levels. The second hole transport auxiliary layer acts as a trap layer between the first hole transport auxiliary layer and the electron blocking layer to temporarily accumulate holes and change the position of residual charge between the electron blocking layer and the light-emitting layer, thereby solving the low grayscale light leakage problem. Therefore, the electroluminescence characteristics of the light-emitting display device can be improved, and the prominence of specific colors or light leakage at low grayscale levels can be prevented.

[0203] The pixel circuit structure of a light-emitting display device according to one embodiment of the present disclosure will be described below.

[0204] Figure 11 This is a cross-sectional view showing a light-emitting display device according to one embodiment of the present disclosure.

[0205] like Figure 11 As shown, the substrate 100 on which each sub-pixel RSP, GSP or BSP is disposed can be formed as a single layer or multiple layers.

[0206] The substrate 100 may include at least one of a glass substrate, a plastic film, or a metal plate having a predetermined supporting force. The substrate 100 may be formed of a flexible material. For example, when the substrate 100 is formed of multiple layers, it may have a stacked structure of a first organic film, an inorganic insulating layer, and a second organic film. The outermost first organic film can prevent the introduction of external impurities and has a protective function. The second organic film can be used to planarize the formation surface of the internal array structure and prevent charge transfer or impurity transfer from the outside to the inside. The inorganic insulating layer between the first and second organic films can be used to prevent the diffusion of moisture and impurities between the first and second organic films.

[0207] A first insulating film 101 may be provided on the substrate 100. The first insulating film 101 may serve as a buffer layer or an active buffer layer. Buffer layers and active buffer layers may be used to prevent impurities from transferring from the underside of wiring and active layers included in the internal array to the upper side, and to support and protect the upper components. The first insulating film 101 may have multiple layers.

[0208] Thin-film transistors (TFTs) and storage capacitors can be disposed on the first insulating film 101 of each sub-pixel RSP, GSP, and BSP.

[0209] A light-blocking layer 111 can be provided on the first insulating film 101 to prevent light from being transmitted from below to the active layer 112 of the thin-film transistor TFT.

[0210] A second insulating film 102 can be provided between the light blocking layer 111 and the active layer 112 for insulation.

[0211] The thin-film transistor (TFT) can be disposed on each of a plurality of sub-pixels on the second insulating film 102. For example, the TFT may include an active layer 112, a gate electrode 113 overlapping the active layer 112, and a first source / drain electrode 114 and a second source / drain electrode 115 connected to both sides of the active layer 112, wherein the third insulating film 103 is interposed between the gate electrode 113 and the active layer 112.

[0212] For example, the storage capacitor may include a first storage electrode and a second storage electrode that overlap each other. At least one of the first storage electrode and the second storage electrode may be formed of the same material as the active layer 112, and the other may include the same material as the gate electrode 113, the first source / drain electrode 114 and the second source / drain electrode 115, and the light blocking layer 111.

[0213] The third insulating film 103 between the active layer 112 and the gate electrode 113 can be used as a gate insulating film.

[0214] The active layer 112 may include, for example, a silicon-based semiconductor or an oxide semiconductor. The silicon-based semiconductor may include crystalline and / or amorphous silicon. The oxide semiconductor may include at least one of gallium oxide, tin oxide, zinc oxide, indium oxide, iron oxide, or indium-gallium-zinc oxide. The oxide semiconductor layer may be formed from multiple layers with different materials or different material composition ratios. Each sub-pixel may include multiple thin-film transistors, and the thin-film transistors may be disposed on different layers. For example, each sub-pixel of substrate 100 may include multiple thin-film transistors with different active layers. For example, a first thin-film transistor may be formed as a silicon-based active layer and may be closer to substrate 100, and a second thin-film transistor may be formed as an oxide semiconductor active layer above the first thin-film transistor.

[0215] The active layer 112 may include a channel region overlapping with the gate electrode 113 and a source / drain region connected to the first source / drain electrode 114 and the second source / drain electrode 115.

[0216] The third insulating film 103 may be selectively disposed corresponding to the channel region of the active layer 112, and may be disposed on the entire surface of the substrate 100 except for the regions through which the first source / drain electrode 114 and the second source / drain electrode 115 pass. The third insulating film 103 may be used to insulate the active layer 112 from the gate electrode 113. The third insulating film 103 may be formed of an inorganic insulating material, and may be formed as, for example, a silicon oxide film (SiOx), a silicon nitride film (SiNx), a silicon oxide nitride film (SiOxNy), or a multilayer film thereof, but is not limited thereto.

[0217] A gate electrode 113 may be formed on the third insulating film 103. The gate electrode 113 may be configured to face the active layer 112, wherein the third insulating film 103 is interposed between the gate electrode 113 and the active layer 112.

[0218] A fourth insulating film 104 can be formed on the gate electrode 113 to cover and protect the gate electrode 113. Additionally, the fourth insulating film 104 can be used to protect at least one electrode and the active layer 112 of the thin-film transistor (TFT). The fourth insulating film 104 can be formed of an inorganic insulating material. For example, the fourth insulating film 104 can be formed as a silicon oxide film (SiOx), a silicon nitride film (SiNx), a silicon oxide nitride film (SiOxNy), or a multilayer film thereof, but is not limited thereto.

[0219] A first source / drain electrode 114 and a second source / drain electrode 115 may be provided on the fourth insulating film 104. The fourth insulating film 104 and the third insulating film 103 may have contact holes to contact the first source / drain electrode 114 and the second source / drain electrode 115 at both ends of the active layer 112, and the corresponding areas may be removed.

[0220] The gate electrode 113, the first source / drain electrode 114, and the second source / drain electrode 115 can each be formed as a single layer or multiple layers.

[0221] When the gate electrode 113, the first source / drain electrode 114, and the second source / drain electrode 115 are monolayers, they can be formed from one or an alloy of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), or copper (Cu). Alternatively, when the gate electrode 113, the first source / drain electrode 114, and the second source / drain electrode 115 comprise multiple layers, they can comprise bilayers of molybdenum / aluminum-neodymium, molybdenum / aluminum, titanium / aluminum, or copper / molybdenum / titanium. Alternatively, the gate electrode 113, the first source / drain electrode 114, and the second source / drain electrode 115 can comprise trilayers of molybdenum / aluminum-neodymium / molybdenum, molybdenum / aluminum / molybdenum, titanium / aluminum / titanium, or molybdenum / copper / molybdenum.

[0222] However, the configuration of the gate electrode 113, the first source / drain electrode 114, and the second source / drain electrode 115 is not limited thereto, and the gate electrode 113, the first source / drain electrode 114, and the second source / drain electrode 115 may comprise a multilayer formed of one or an alloy of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), or copper (Cu).

[0223] The first to fourth insulating films 101, 102, 103 and 104 can each be formed as inorganic insulating films. The inorganic insulating films can be formed as, for example, at least one of silicon oxide films, silicon nitride films or silicon oxide nitride films, but are not limited thereto.

[0224] A first planarization film 105 and a second planarization film 106 may be disposed on the first to fourth insulating films 101, 102, 103, and 104. The first planarization film 105 may have contact holes, and a connection electrode 116 connected to the second source / drain electrode 115 may be disposed in the contact holes. The second planarization film 106 is configured to cover the connection electrode 116 and the first planarization film 105. The first planarization film 105 and the second planarization film 106 may each comprise an organic material. The organic material may include at least one material selected from acrylic resin, phenolic resin, polyimide resin, unsaturated polyester resin, polyamide resin, benzocyclobutene resin, polystyrene resin, or polyphenylene sulfide resin.

[0225] For example, the connecting electrode 116 can be configured as a multilayer formed of one or an alloy of molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu). However, embodiments of this disclosure are not limited thereto. In some cases, the connecting electrode 116 can be omitted. When the connecting electrode 116 is omitted, one of the first source / drain electrode 114 and the second source / drain electrode 115 can be directly connected to the first electrode 122 of the light-emitting device ED.

[0226] The light-emitting device ED is formed by laminating a first electrode 122, an intermediate layer EL, and a second electrode 126.

[0227] The first electrode 122 can act as an anode. The first electrode 122 can pass through the second planarization film 106 and the first planarization film 105 and is connected to the transistor TFT. In the illustrated example, a connection electrode 116 is also disposed between the first electrode 122 and the transistor TFT, and the transistor TFT is connected to the connection electrode 116, which is also connected to the first electrode 122. However, the second source / drain electrode 115 of the transistor TFT and the first electrode 122 of the light-emitting device ED can be directly connected without the need for the connection electrode 116.

[0228] The first electrode 122 may include, for example, a metallic material with high reflectivity. For example, the first electrode 122 may be formed as a multilayer structure, such as a stacked structure of aluminum (Al) and titanium (Ti) (Ti / Al / Ti), a stacked structure of aluminum (Al) and ITO (ITO / Al / ITO), an APC (Ag / Pd / Cu) alloy, a stacked structure of APC alloy and ITO (ITO / APC / ITO), a stacked structure of silver (Ag) and molybdenum / titanium alloy (Ag / MoTi), or the first electrode 122 may include a single-layer structure formed of one material selected from silver (Ag), aluminum (Al), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba), or an alloy of two or more of these materials, but is not limited thereto. The first electrode 122 may be referred to as a "reflective electrode".

[0229] An intermediate layer EL is disposed on the first electrode 122. The intermediate layer EL may include a red intermediate layer REL in the red sub-pixel RSP, a green intermediate layer GEL in the green sub-pixel GSP, and a blue intermediate layer BEL in the blue sub-pixel BSP. The configuration of the intermediate layer for each sub-pixel is as follows: Figure 4 Configuration.

[0230] The red emitting layer REML can be individually included in the red sub-pixel RSP, the green emitting layer GEML can be individually included in the green sub-pixel GSP, and the blue emitting layer BEML can be individually included in the blue sub-pixel BSP. For example, the red emitting layer REML can be patterned in the red sub-pixel RSP, the green emitting layer GEML can be patterned in the green sub-pixel GSP, and the blue emitting layer BEML can be patterned in the blue sub-pixel BSP. However, this is provided only as an example. The red intermediate layer REL, the green intermediate layer GEL, and the blue intermediate layer BEM can have a series structure, wherein a charge generation layer is disposed between multiple stacks. For example, the light-emitting device ED of each sub-pixel RSP, GSP, or BSP can have multiple stacks, wherein the intermediate layer EL is laminated between the first electrode 122 and the second electrode 126, the first common layer CML1, the respective color emitting layers REML, GEML, and BEML, and the second common layer CML2, and can include a charge generation layer between adjacent stacks. This series structure includes a charge generation layer between stacks, and each stack can include one or more emitting layers. In this cascaded structure, as described above, a first hole transport auxiliary layer and a second hole transport auxiliary layer with different HOMO energy levels can be applied to at least one stack of green sub-pixels.

[0231] The edge of the first electrode 122 of each sub-pixel RSP, GSP, and BSP may overlap with the dam 150. The area of ​​the first electrode 122 exposed from the dam 150 may be a light-emitting portion REM, GEM, or BEM. The dam 150 exposes the light-emitting portion REM, GEM, or BEM of each sub-pixel RSP, GSP, and BSP. The dam 150 may include organic or inorganic insulating materials.

[0232] When a voltage is applied to the first electrode 122 and the second electrode 126, holes and electrons migrate to the organic light-emitting layer through the hole injection layer and the hole transport layer, and the electron injection layer and the electron transport layer, respectively. In the organic light-emitting layer, holes and electrons combine with each other to form excitons, and the excitons descend from the excited state to the ground state, thereby causing light emission.

[0233] In the multilayer system including intermediate layers (EL: REL, GEL, BEL), the hole transport common layer CML1 and the electron transport common layer CML2 can be set together in the entire display area AA.

[0234] The second electrode 126 can be a common layer disposed in the sub-pixel SP and subjected to the same voltage. For this purpose, the second electrode 126 can extend from the display area AA to a portion of the non-display area NA.

[0235] The second electrode 126 can be a light-transmitting electrode. The second electrode 126 acts as a cathode. The second electrode 126 can include: a transparent metallic material (TCO, transparent conductive material) that can transmit light, such as ITO (indium tin oxide) or IZO (indium zinc oxide); or a semi-transmitting metallic material (semi-transmitting conductive material), such as magnesium (Mg), silver (Ag), or an alloy of magnesium (Mg) and silver (Ag). When the second electrode 126 includes a semi-transmitting metallic material, the luminous efficiency can be increased through the microcavity effect. When the second electrode 126 includes a semi-transmitting metallic material, its thickness can be small enough to transmit light.

[0236] The first electrode 122 may include a reflective electrode to prevent light generated in the intermediate layer EL from being transmitted to a light-shielding component below the first electrode 122. The light generated in the intermediate layer EL resonates between the second electrode 126 and the first electrode 122, and is ultimately emitted upwards through the second electrode 126. Because the first electrode 122 includes a reflective component, light emitted from the light-emitting device ED can be identified in the light-emitting portion REM, GEM, or BEM, regardless of their arrangement, even though the first electrode 122 overlaps with wiring and transistor TFTs.

[0237] An encapsulation layer 140 protecting the light-emitting device ED can also be provided on the second electrode 126. The encapsulation layer 140 can be a single layer or multiple layers. When the encapsulation layer 140 is configured as multiple layers, it can be formed by laminating at least one inorganic encapsulation film with at least one organic encapsulation film. The inorganic encapsulation film can prevent moisture penetration, and the organic encapsulation film can cover particles and planarize the surface. The organic encapsulation film can be located inside the inorganic encapsulation film in a planar position. In this case, the inorganic encapsulation film can prevent moisture penetration to the sides.

[0238] According to one embodiment of the present disclosure, a light-emitting device has the following configuration: a plurality of hole transport auxiliary layers are separated from the light-emitting layer, wherein an electron blocking layer is located between the plurality of hole transport auxiliary layers and the light-emitting layer, and a second hole transport auxiliary layer adjacent to the electron blocking layer is formed of a material having a high HOMO energy level, such that when a charge is discharged, the charge can easily migrate across the electron blocking layer to the second hole transport auxiliary layer, thereby preventing light leakage caused by the charge retained in the layer adjacent to the light-emitting layer.

[0239] A light-emitting device according to one embodiment of this disclosure may include: a first electrode and a second electrode facing each other; a light-emitting layer between the first electrode and the second electrode; a hole transport common layer between the first electrode and the light-emitting layer and an electron transport common layer between the light-emitting layer and the second electrode; a first hole transport auxiliary layer and a second hole transport auxiliary layer sequentially disposed between the hole transport common layer and the light-emitting layer; and an electron blocking layer between the second hole transport auxiliary layer and the light-emitting layer. The HOMO energy level of the second hole transport auxiliary layer may be higher than the HOMO energy levels of each of the first hole transport auxiliary layer and the electron blocking layer located on both sides of the second hole transport auxiliary layer.

[0240] In one embodiment of the light-emitting device according to the present disclosure, the HOMO energy level of the second hole transport auxiliary layer may be higher than the HOMO energy level of the light-emitting layer.

[0241] In one embodiment of the light-emitting device according to the present disclosure, the second hole transport auxiliary layer may have a smaller band gap than each of the first hole transport auxiliary layer and the electron blocking layer.

[0242] In one embodiment of the light-emitting device according to the present disclosure, the first hole transport auxiliary layer may have a hole mobility greater than that of the second hole transport auxiliary layer.

[0243] In one embodiment of the light-emitting device according to the present disclosure, the refractive index of the first hole transport auxiliary layer may be greater than 2.0, and the refractive index of the second hole transport auxiliary layer may be lower than the refractive index of the first hole transport auxiliary layer.

[0244] In a light-emitting device according to one embodiment of the present disclosure, a first hole transport auxiliary layer may have one surface in contact with a hole transport common layer and another surface in contact with a second hole transport auxiliary layer. An electron blocking layer may have one surface in contact with the second hole transport auxiliary layer and another surface in contact with the light-emitting layer.

[0245] In one embodiment of the light-emitting device according to the present disclosure, the difference between the HOMO energy level of the first hole transport auxiliary layer and the HOMO energy level of the hole transport common layer in contact with the first hole transport auxiliary layer can be 0.15 eV or less.

[0246] In one embodiment of the light-emitting device according to the present disclosure, the difference between the HOMO energy level of the second hole transport assist layer and the HOMO energy level of the electron blocking layer in contact with the second hole transport assist layer can be 0.25 eV or greater.

[0247] In one embodiment of the light-emitting device according to the present disclosure, the first HOMO energy level difference between the second hole transport assist layer and the electron blocking layer may be greater than the second HOMO energy level difference between the second hole transport assist layer and the first hole transport assist layer.

[0248] In one embodiment of the light-emitting device according to this disclosure, the first hole transport auxiliary layer may be thicker than the second hole transport auxiliary layer. The thickness of the first hole transport auxiliary layer may be proportional to the wavelength of the color of the light emitted from the light-emitting layer.

[0249] In one embodiment of the light-emitting device according to this disclosure, the thickness of the second hole transport auxiliary layer may be from 30 Å to 70 Å.

[0250] In one embodiment of the light-emitting device according to this disclosure, the hole transport common layer may include a hole injection layer and a hole transport layer. The hole transport layer may be in contact with a first hole transport auxiliary layer.

[0251] In one embodiment of the light-emitting device according to this disclosure, the electron transport common layer may include a hole blocking layer, an electron transport layer, and an electron injection layer. The hole blocking layer may be in contact with the light-emitting layer.

[0252] In one embodiment of the light-emitting device according to the present disclosure, the light-emitting layer may include a phosphorescent dopant having an emission peak with a wavelength of 500 nm to 700 nm.

[0253] An embodiment of the present disclosure of a light-emitting display device may include: a substrate comprising a plurality of sub-pixels; a light-emitting device disposed in at least one sub-pixel; and a thin-film transistor connected to the light-emitting device.

[0254] In one embodiment of the light-emitting display device according to the present disclosure, the first hole transport auxiliary layer and the second hole transport auxiliary layer may be spaced apart from adjacent sub-pixels, and the electron blocking layer may be continuous in a plurality of sub-pixels.

[0255] A light-emitting display device according to one embodiment of the present disclosure may include: a substrate including green sub-pixels, red sub-pixels, and blue sub-pixels; a first electrode at each of the green, red, and blue sub-pixels; a hole transport common layer disposed on the first electrode across the green, red, and blue sub-pixels; a green light-emitting layer, a red light-emitting layer, and a blue light-emitting layer disposed on the hole transport common layer at each of the green, red, and blue sub-pixels; a first hole transport auxiliary layer, a second hole transport auxiliary layer, and an electron blocking layer sequentially disposed between the hole transport common layer and the green light-emitting layer in the green sub-pixels; an electron transport common layer disposed on the green, red, and blue light-emitting layers across the green, red, and blue sub-pixels; and a second electrode on the electron transport common layer. The HOMO energy level of the second hole transport auxiliary layer may be higher than the HOMO energy levels of each of the first hole transport auxiliary layer and the electron blocking layer located on either side of the second hole transport auxiliary layer.

[0256] According to one embodiment of the present disclosure, the light-emitting display device may further include a third hole transport auxiliary layer, a fourth hole transport auxiliary layer, and an electron blocking layer sequentially disposed between a hole transport common layer and a red light-emitting layer at a red sub-pixel. The HOMO energy level of the fourth hole transport auxiliary layer may be higher than the HOMO energy levels of each of the third hole transport auxiliary layer and the electron blocking layer located on either side of the fourth hole transport auxiliary layer.

[0257] In one embodiment of the light-emitting display device according to the present disclosure, the third hole transport auxiliary layer may be thicker than the first hole transport auxiliary layer.

[0258] In one embodiment of the light-emitting display device according to the present disclosure, the second hole transport auxiliary layer may be thicker than the fourth hole transport auxiliary layer.

[0259] In one embodiment of the light-emitting display device according to the present disclosure, the electron blocking layer may contact the second hole transport auxiliary layer at the green sub-pixel and may contact the fourth hole transport auxiliary layer at the red sub-pixel.

[0260] In one embodiment of the light-emitting display device according to the present disclosure, the first hole transport auxiliary layer and the second hole transport auxiliary layer do not need to overlap with the red sub-pixel and the blue sub-pixel.

[0261] As will be apparent from the foregoing, the light-emitting device and light-emitting display apparatus according to this disclosure have the following effects.

[0262] According to one embodiment of the present disclosure, a light-emitting device has the following configuration: a plurality of hole transport auxiliary layers are separated from the light-emitting layer, wherein an electron blocking layer is located between the plurality of hole transport auxiliary layers and the light-emitting layer, and a second hole transport auxiliary layer adjacent to the electron blocking layer is formed of a material having a high HOMO energy level, such that when a charge is discharged, the charge can easily migrate across the electron blocking layer to the second hole transport auxiliary layer, thereby preventing light leakage caused by the charge retained in the layer adjacent to the light-emitting layer.

[0263] The second hole transport auxiliary layer is formed of a material with a high surface potential, which enables excellent transient discharge through the contact surface. Therefore, transient discharge from the light-emitting layer in the off state to the second hole transport auxiliary layer from a relatively far distance is possible, thereby preventing low-grayscale light leakage.

[0264] The first hole transport auxiliary layer is formed of a high refractive index material, and therefore depends on the color of the light emitted from the light-emitting layer to be optimal for resonance, and the second hole transport auxiliary layer is formed of a material with a lower refractive index than the first hole transport auxiliary layer, and therefore maximizes the microcavity effect and facilitates the discharge function in the off state.

[0265] The light-emitting display device according to the embodiments of this disclosure can achieve energy balance, prevent specific light leakage at low gray levels, and ultimately improve light-emitting characteristics by differentially changing the configuration of the hole transport auxiliary layer in each sub-pixel.

[0266] It will be apparent to those skilled in the art that various modifications and variations can be made to this disclosure without departing from the spirit or scope of the invention. Therefore, this disclosure is intended to cover modifications and variations of the invention, provided 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; A light-emitting layer between the first electrode and the second electrode; A hole transport common layer between the first electrode and the light-emitting layer, and an electron transport common layer between the light-emitting layer and the second electrode; A first hole transport auxiliary layer and a second hole transport auxiliary layer are sequentially disposed between the hole transport common layer and the light-emitting layer; as well as An electron blocking layer between the second hole transport assist layer and the light-emitting layer. The highest occupied molecular orbital (HOMO) energy level of the second hole transport assist layer is higher than the HOMO energy levels of each of the first hole transport assist layer and the electron blocking layer located on opposite sides of the second hole transport assist layer.

2. The light-emitting device according to claim 1, wherein, The HOMO energy level of the second hole transport auxiliary layer is higher than the HOMO energy level of the light-emitting layer.

3. The light-emitting device according to claim 1, wherein, The second hole transport assist layer has a smaller band gap than each of the first hole transport assist layer and the electron blocking layer.

4. The light-emitting device according to claim 1, wherein, The first hole transport auxiliary layer has a hole mobility rate that is greater than that of the second hole transport auxiliary layer.

5. The light-emitting device according to claim 1, wherein, The refractive index of the first hole transport auxiliary layer is greater than about 2.0, and the refractive index of the second hole transport auxiliary layer is lower than that of the first hole transport auxiliary layer.

6. The light-emitting device according to claim 1, wherein, The first hole transport auxiliary layer has one surface that contacts the hole transport common layer and another surface that contacts the second hole transport auxiliary layer, and The electron blocking layer has one surface that contacts the second hole transport auxiliary layer and another surface that contacts the light-emitting layer.

7. The light-emitting device according to claim 1, wherein, The difference between the HOMO energy level of the first hole transport auxiliary layer and the HOMO energy level of the hole transport common layer in contact with the first hole transport auxiliary layer is about 0.15 eV or less.

8. The light-emitting device according to claim 1, wherein, The difference between the HOMO energy level of the second hole transport assist layer and the HOMO energy level of the electron blocking layer in contact with the second hole transport assist layer is about 0.25 eV or greater.

9. The light-emitting device according to claim 1, wherein, The first HOMO energy level difference between the second hole transport auxiliary layer and the electron blocking layer is greater than the second HOMO energy level difference between the second hole transport auxiliary layer and the first hole transport auxiliary layer.

10. The light-emitting device according to claim 1, wherein, The thickness of the first hole transport auxiliary layer is greater than the thickness of the second hole transport auxiliary layer, and the thickness of the first hole transport auxiliary layer is proportional to the wavelength of the color of the light emitted from the light-emitting layer.

11. The light-emitting device according to claim 1, wherein, The thickness of the second hole transport auxiliary layer is approximately 30 Å to 70 Å.

12. The light-emitting device according to claim 1, wherein, The hole transport common layer includes a hole injection layer and a hole transport layer, and The hole transport layer is in contact with the first hole transport auxiliary layer.

13. The light-emitting device according to claim 1, wherein, The electron transport common layer includes a hole blocking layer, an electron transport layer, and an electron injection layer, and The hole blocking layer is in contact with the light-emitting layer.

14. The light-emitting device according to claim 1, wherein, The light-emitting layer includes a phosphorescent dopant with an emission peak at a wavelength of approximately 500 nm to 700 nm.

15. The light-emitting device according to claim 1, wherein, The second hole transport auxiliary layer has a thickness of 1 / 30 to 1 / 3 of the total thickness of the first hole transport auxiliary layer and the second hole transport auxiliary layer.

16. The light-emitting device according to claim 1, wherein, The band gap of the luminescent layer is smaller than that of the other layers, and the lowest unoccupied molecular orbital (LUMO) energy level of the luminescent layer is lower than that of the other layers.

17. A light-emitting display device, comprising: A substrate comprising multiple sub-pixels; The light-emitting device according to any one of claims 1 to 16, wherein the light-emitting device is disposed in at least one sub-pixel of the plurality of sub-pixels; as well as A thin-film transistor connected to the light-emitting device.

18. The light-emitting display device according to claim 17, wherein, The first hole transport auxiliary layer and the second hole transport auxiliary layer are spaced apart from adjacent sub-pixels among the plurality of sub-pixels, and The electron blocking layer extends continuously within the plurality of sub-pixels.

19. A light-emitting display device, comprising: A substrate including green sub-pixels, red sub-pixels, and blue sub-pixels; A first electrode at each of the green sub-pixel, the red sub-pixel, and the blue sub-pixel; A common hole transport layer on the first electrode across the green sub-pixel, the red sub-pixel, and the blue sub-pixel; Green emitting layer, red emitting layer and blue emitting layer on the hole transport common layer at each of the green sub-pixel, the red sub-pixel and the blue sub-pixel respectively; A first hole transport auxiliary layer, a second hole transport auxiliary layer, and an electron blocking layer are sequentially disposed between the hole transport common layer and the green light-emitting layer in the green sub-pixel; An electron transport common layer across the green sub-pixel, the red sub-pixel, and the blue sub-pixel on the green light-emitting layer, the red light-emitting layer, and the blue light-emitting layer; as well as The second electrode on the electron transport common layer, The highest occupied molecular orbital (HOMO) energy level of the second hole transport auxiliary layer is higher than the HOMO energy level of each of the electron blocking layers of the first hole transport auxiliary layer located on the opposite side of the second hole transport auxiliary layer.

20. The light-emitting display device according to claim 19, further comprising a third hole transport auxiliary layer, a fourth hole transport auxiliary layer, and the electron blocking layer sequentially disposed between the hole transport common layer and the red light-emitting layer at the red sub-pixel. in, The HOMO level of the fourth hole transport auxiliary layer is higher than the HOMO levels of each of the third hole transport auxiliary layer and the electron blocking layer located on the opposite side of the fourth hole transport auxiliary layer.

21. The light-emitting display device according to claim 20, wherein, The thickness of the third hole transport auxiliary layer is greater than the thickness of the first hole transport auxiliary layer.

22. The light-emitting display device according to claim 21, wherein, The second hole transport auxiliary layer is thicker than the fourth hole transport auxiliary layer.

23. The light-emitting display device according to claim 20, wherein, The electron blocking layer contacts the second hole transport auxiliary layer at the green sub-pixel and the fourth hole transport auxiliary layer at the red sub-pixel.

24. The light-emitting display device according to claim 19, wherein, The first hole transport auxiliary layer and the second hole transport auxiliary layer do not overlap with the red sub-pixel and the blue sub-pixel.

25. A light-emitting device, comprising: The first and second electrodes facing each other; A light-emitting layer between the first electrode and the second electrode; A hole transport common layer between the first electrode and the light-emitting layer, and an electron transport common layer between the light-emitting layer and the second electrode; A first hole transport auxiliary layer and a second hole transport auxiliary layer are disposed between the hole transport common layer and the light-emitting layer; as well as An electron blocking layer between the second hole transport assist layer and the light-emitting layer. The first hole transport assist layer comprises the material of the second hole transport assist layer and the material of the electron blocking layer, and The second hole transport auxiliary layer, which serves as a trap layer between the first hole transport auxiliary layer and the electron blocking layer, has the highest occupied molecular orbital (HOMO) energy level.

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