Organometallic Compound and Organic Light-Emitting Diode Comprising the Same

Abstract

A novel organometallic compound is disclosed, which reduces or inhibits triplet exciton quenching (TPQ) and decay phenomena, thereby improving the luminous efficiency and lifetime of an organic light-emitting diode including the compound. In addition, an organic light-emitting diode including the compound is disclosed. The organic light-emitting diode including the compound includes a first electrode, a second electrode, and one or more light-emitting stacks disposed between the first electrode and the second electrode.

Description

Technical Field

[0001] The present disclosure relates to an organometallic compound and an organic light emitting diode including the organometallic compound. More specifically, the present disclosure relates to an organometallic compound and an organic light emitting diode including the organometallic compound, which reduces or inhibits the TPQ (Triplet Polaron Quenching) phenomenon and the roll-off phenomenon to improve the luminous efficiency and lifespan of the organic light emitting diode including the organometallic compound. Background Art

[0002] As display devices are applied to various fields, the interest in display devices is increasing day by day. One type of display device is an organic light emitting display device including organic light emitting diodes (OLEDs) that are rapidly developing. Organic light emitting diodes emit light. Compared with conventional display devices, organic light emitting diodes can operate at a low voltage, consume relatively little power, exhibit excellent colors, and can be used in various ways because a flexible substrate can be applied thereto. In addition, the size of the organic light emitting diode can be freely adjusted.

[0003] Compared with liquid crystal displays (LCDs), organic light emitting diodes (OLEDs) have excellent viewing angles and contrast ratios, and are lightweight and ultrathin because OLEDs do not require a backlight. The organic light emitting diode includes a plurality of organic layers between a negative electrode (electron injection electrode; cathode) and a positive electrode (hole injection electrode; anode). The plurality of organic layers may include a hole injection layer, a hole transport layer, a hole transport auxiliary layer, an electron blocking layer, a light emitting layer, an electron transport layer, and the like.

[0004] In this organic light emitting diode structure, when a voltage is applied to the two electrodes, electrons and holes are respectively injected into the light emitting layer from the negative electrode and the positive electrode. Therefore, excitons are generated in the light emitting layer and then fall to the ground state, thereby emitting light.

[0005] In an organic light emitting diode, charges are injected into the light emitting layer formed between the anode and the cathode, such that electrons and holes pair with each other and recombine with each other to generate excitons, and the energy of the excitons is converted into light.

[0006] In this regard, excitons exist in the form of singlet excitons and triplet excitons. In recent years, there has been a trend to use phosphorescent materials instead of fluorescent materials for the light emitting layer. When a fluorescent light emitting material is used, about 25% of the singlet excitons generated in the light emitting layer are used for light emission, while most of the triplet excitons, about 75% of the excitons generated in the light emitting layer, are dissipated as heat. However, when a phosphorescent light emitting material is used, both singlet and triplet states are used for light emission.

[0007] In a phosphorescent organic light-emitting diode, a phenomenon called "triplet exciton quenching (TPQ)" may occur, in which triplet excitons are quenched by polarons that are not converted into excitons at the interface between the hole transport layer (HTL) and the emitting layer (EML) and inside the emitting layer (EML), thereby degrading the performance of the organic light-emitting diode.

[0008] Specifically, when holes are transported from the hole transport layer (HTL) to the interface of the emitting layer (EML), the holes can be transported to a large number of emitting layers or to the dopants therein. In this regard, when holes from the hole transport layer move to the dopants, the TPQ phenomenon increases. This is a factor that reduces the efficiency of the organic light-emitting diode.

[0009] In addition, polarons that are not converted into excitons inside the emitting layer react with the dopants of the emitting layer, resulting in a quenching phenomenon. This TPQ phenomenon not only reduces the efficiency of the organic light-emitting diode, but also exacerbates the attenuation phenomenon that causes color shift based on current density, thereby degrading the performance of the organic light-emitting diode.

[0010] Therefore, in order to further improve the performance of organic light-emitting diodes using phosphorescent light-emitting materials, it is necessary to develop a scheme that can reduce or suppress the TPQ phenomenon and the attenuation phenomenon occurring in organic light-emitting diodes. Summary of the Invention

[0011] An object of the present disclosure is to provide an organometallic compound having a novel structure, which can be incorporated into the emitting layer of an organic light-emitting diode.

[0012] In addition, an object of the present disclosure is to provide a charge scavenger that causes polaron quenching to reduce the triplet polaron quenching (TPQ) and attenuation phenomena occurring in an organic light-emitting diode, and to provide an organic light-emitting diode including the charge scavenger.

[0013] Furthermore, an object of the present disclosure is to provide an organometallic compound that acts as a charge scavenger to reduce the operating voltage of an organic light-emitting diode and improve the efficiency and lifespan of the organic light-emitting diode, and to provide an organic light-emitting diode including an organic emitting layer containing the organometallic compound.

[0014] The objects of the present disclosure are not limited to the above objects. Other objects and advantages of the present disclosure not mentioned can be understood based on the following description, and can be more clearly understood based on the embodiments of the present disclosure. In addition, it will be readily understood that the objects and advantages of the present disclosure can be achieved using the means shown in the claims and their combinations.

[0015] To achieve the above objects, one aspect of the present disclosure provides an organometallic compound having a novel structure represented by the following Chemical Formula 1:

[0016] [Chemical Formula 1] Ir(L A ) m (L B ) n

[0017] wherein in Chemical Formula 1, L A may be a main ligand represented by one selected from the group consisting of the following Chemical Formulas 2-1 to 2-3, and L B may be a co-ligand represented by the following Chemical Formula 3:

[0018] [Chemical Formula 2-1]

[0019] [Chemical Formula 2-2]

[0020] [Chemical Formula 2-3]

[0021] [Chemical Formula 3]

[0022] wherein in each of Chemical Formulas 2-1 to 2-3,

[0023] X may represent one selected from the group consisting of O, S, NR7, and C(R8)(R9),

[0024] R 1-1 、R 1-2 、R 1-3 、R 1-4 、R 2-1 、R 2-2 、R 2-3 、R 2-4 、R 3-1 、R 3-2 、R 3-3 、R 3-4 、R 4-1 、R 4-2 and R 4-3 each may independently represent one selected from the group consisting of the following: hydrogen, deuterium, a halogen atom, a C1-C30 alkyl group, a C3-C30 cycloalkyl group, a C1-C30 heteroalkyl group, a C7-C30 arylalkyl group, a C1-C30 alkoxy group, a C6-C30 aryloxy group, an amino group, a silyl group, a C2-C30 alkenyl group, a C3-C30 cycloalkenyl group, a C3-C30 heteroalkenyl group, a C2-C30 alkynyl group, a C6-C40 aryl group, a C3-C40 heteroaryl group, an acyl group, a carbonyl group, a carboxylic acid, an ester, a nitrile, an isonitrile, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group, and combinations thereof,

[0025] R 1-1 、R1-2 , R 1-3 , R 1-4 , R 2-1 , R 2-2 , R 2-3 , R 2-4 , R 3-1 , R 3-2 , R 3-3 , R 3-4 , R 4-1 , R 4-2 and R 4-3 Two adjacent substituents in and R can be connected to each other to form a ring structure selected from the group consisting of: substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C2-C20 heterocycloalkyl, substituted or unsubstituted C7-C20 arylalkyl, substituted or unsubstituted C2-C20 heteroarylalkyl, substituted or unsubstituted C3-C20 cycloalkenyl, substituted or unsubstituted C6-C30 aryl, and substituted or unsubstituted C3-C30 heteroaryl,

[0026] R7, R8, and R9 can each independently represent one selected from the group consisting of: C1-C30 alkyl, C3-C30 cycloalkyl, C1-C30 heteroalkyl, C7-C30 arylalkyl, C1-C30 alkoxy, C6-C30 aryloxy, amino, silyl, C2-C30 alkenyl, C3-C30 cycloalkenyl, C3-C30 heteroalkenyl, C2-C30 alkynyl, C6-C40 aryl, and C3-C40 heteroaryl,

[0027] wherein in Chemical Formula 3,

[0028] R 5-1 , R 5-2 , R 5-3 , R 5-4 , R 6-1 , R 6-2 , R 6-3 and R 6-4 can each independently represent one selected from the group consisting of hydrogen, deuterium, C1-C5 straight-chain alkyl, and C1-C5 branched alkyl, wherein the C1-C5 straight-chain alkyl or C1-C5 branched alkyl can be substituted by at least one selected from deuterium and halogen,

[0029] R 5-1 , R 5-2 , R 5-3 , R 5-4 , R 6-1 , R 6-2 , R 6-3 and R 6-4Two adjacent substituents in [the compound] may be connected to each other to form a ring structure selected from the group consisting of: substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C2-C20 heterocycloalkyl, substituted or unsubstituted C7-C20 arylalkyl, substituted or unsubstituted C2-C20 heteroarylalkyl, substituted or unsubstituted C3-C20 cycloalkenyl, substituted or unsubstituted C6-C30 aryl, and substituted or unsubstituted C3-C30 heteroaryl.

[0030] m may be 1, 2, or 3, n may be 0, 1, or 2, and the sum of m and n may be 3.

[0031] Another aspect of the present disclosure provides an organic light-emitting device including: a first electrode; a second electrode facing the first electrode; and a light-emitting stack disposed between the first electrode and the second electrode, wherein the light-emitting stack includes an organic layer, wherein the organic layer includes a hole transport layer and a red light-emitting layer, wherein the hole transport layer includes a hole transport material, wherein the red light-emitting layer contains a red host, a red dopant, and a charge scavenger, and wherein the charge scavenger includes an organometallic compound having a novel structure represented by Chemical Formula 1 above.

[0032] The organometallic compound according to the present disclosure may be included in the light-emitting layer of an organic light-emitting diode such that the triplet exciton quenching (TPQ) phenomenon and the decay phenomenon occurring in the organic light-emitting diode can be reduced or suppressed. Accordingly, the operating voltage of the organic light-emitting diode can be lowered, and the efficiency and lifetime characteristics of the organic light-emitting diode can be improved.

[0033] The effects of the present disclosure are not limited to the above effects, and other effects not mentioned will be clearly understood by those skilled in the art from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a cross-sectional view schematically showing an organic light-emitting diode in which the light-emitting layer contains an organometallic compound according to an exemplary embodiment of the present disclosure.

[0035] Figure 2 is a cross-sectional view schematically showing an organic light-emitting diode having a tandem structure including two light-emitting stacks and containing the organometallic compound represented by Chemical Formula 1 according to an exemplary embodiment of the present disclosure.

[0036] Figure 3 is a cross-sectional view schematically showing an organic light-emitting diode having a tandem structure including three light-emitting stacks and containing the organometallic compound represented by Chemical Formula 1 according to an exemplary embodiment of the present disclosure.

[0037] Figure 4It is a cross-sectional view schematically showing an organic light-emitting display device including an organic light-emitting diode according to an exemplary embodiment of the present disclosure. Detailed Embodiments

[0038] Advantages and features of the present disclosure, and methods for achieving these advantages and features, will become clear with reference to embodiments described in detail below in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below, but may be implemented in various different forms. Therefore, these embodiments are described only to make the present disclosure complete and to fully inform those of ordinary skill in the art to which the present disclosure pertains of the scope of the present disclosure, and the present disclosure is defined only by the scope of the claims.

[0039] The shapes, sizes, ratios, angles, quantities, etc. disclosed in the accompanying drawings for describing the embodiments of the present disclosure are only exemplary, and the present disclosure is not limited to these. In this application, the same reference numerals refer to the same elements. In addition, for simplicity of description, descriptions and details of well-known steps and elements are omitted. Furthermore, in the following detailed description of the present disclosure, many details are set forth to provide a comprehensive understanding of the present disclosure. However, it should be understood that the present disclosure may be practiced without these specific details. In other cases, well-known methods, processes, components, and circuits are not described in detail so as not to unnecessarily obscure aspects of the present disclosure.

[0040] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the present disclosure. Unless the context clearly indicates otherwise, the singular forms "a" and "an" used herein are also intended to include the plural forms. It will be further understood that when used in this specification, the terms "comprise", "including", "include", and "including" specify the presence of the stated features, integers, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, operations, elements, components, and / or portions thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. When a phrase such as "at least one" precedes a list of elements, it may modify the entire list of elements and may not modify the individual elements of the list. In the interpretation of numerical values, errors or tolerances may occur even without their explicit description.

[0041] In addition, it should also be understood that when a first element or layer is referred to as being 'on' a second element or layer, the first element can be directly disposed on the second element, or can be indirectly disposed on the second element, wherein a third element or layer is disposed between the first element or layer and the second element or layer. It should be understood that when an element or layer is referred to as 'connected to' or 'coupled to' another element or layer, it can be directly on the other element or layer, directly connected to or coupled to the other element or layer, or there can be one or more intermediate elements or layers. In addition, it should also be understood that when an element or layer is referred to as being 'between' two elements or layers, it can be the only element or layer between the two elements or layers, or there can also be one or more intermediate elements or layers.

[0042] In addition, as used herein, when a layer, film, region, plate, etc. is disposed 'on' or 'above' another layer, film, region, plate, etc., the former can directly contact the latter, or another layer, film, region, plate, etc. can be disposed between the former and the latter. As used herein, when a layer, film, region, plate, etc. is directly disposed 'on' or 'above' another layer, film, region, plate, etc., the former directly contacts the latter, and there is no other layer, film, region, plate, etc. disposed between the former and the latter. In addition, as used herein, when a layer, film, region, plate, etc. is disposed 'under' or 'below' another layer, film, region, plate, etc., the former can directly contact the latter, or another layer, film, region, plate, etc. can be disposed between the former and the latter. As used herein, when a layer, film, region, plate, etc. is directly disposed 'under' or 'below' another layer, film, region, plate, etc., the former directly contacts the latter, and there is no other layer, film, region, plate, etc. disposed between the former and the latter.

[0043] In the description of temporal relationships, for example, the temporal sequence relationship between two events, such as 'after', 'after...', 'before', etc., unless indicating 'directly after', 'immediately after' or 'directly before', another event may occur between them.

[0044] It should be understood that although the terms 'first','second', 'third', etc. may be used herein to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Thus, without departing from the spirit and scope of the present disclosure, the first element, component, region, layer or part described below can be referred to as the second element, component, region, layer or part.

[0045] The features of the various embodiments of the present disclosure can be partially or completely combined with each other and can be technically related or operable with each other. The embodiments can be implemented independently of each other and can be implemented together in an associated relationship.

[0046] When interpreting a numerical value, unless there is a separate and explicit description, the value is interpreted to include the error range.

[0047] It should be understood that when an element or layer is referred to as "connected to" or "coupled to" another element or layer, it can be directly on the other element or layer, directly connected to or coupled to the other element or layer, or there can be one or more intermediate elements or layers. Additionally, it should also be understood that when an element or layer is referred to as "between" two elements or layers, it can be the only element or layer between the two elements or layers, or there can also be one or more intermediate elements or layers.

[0048] The features of the various embodiments of the present disclosure can be partially or completely combined with each other and can be technically related or operable with each other. The embodiments can be implemented independently of each other and can be implemented together in an associated relationship.

[0049] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive concept belongs. It will be further understood that terms such as those defined in a common dictionary should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless explicitly so defined herein.

[0050] As used herein, the phrase "adjacent substituents are connected to each other to form a ring (or ring structure)" means that adjacent substituents can combine with each other to form a substituted or unsubstituted alicyclic ring or aromatic ring. The phrase "substituent adjacent to" a certain substituent can mean a substituent that substitutes an atom directly connected to the atom substituted by the certain substituent, a substituent that is spatially closest to the certain substituent, or a substituent that substitutes the atom substituted by the certain substituent. For example, two substituents at the ortho positions of a benzene ring structure and two substituents on the same carbon of an aliphatic ring can be interpreted as "adjacent substituents".

[0051] In the present disclosure, the HOMO (highest occupied molecular orbital) energy level is calculated based on cyclic voltammetry (CV) and based on the following conditions and equations.

[0052]

[0053] In the present disclosure, the triplet energy (T1) is obtained as follows: the photoluminescence of a solution of a material to be measured dissolved in a 2-methyl THF solvent is measured at an environment of 77K to obtain a PL spectrum, and the energy level (unit: eV) of the first peak of the obtained PL spectrum is converted into the triplet energy.

[0054] Hereinafter, the structure of the organometallic compound according to the present disclosure and the organic light-emitting diode including the organometallic compound will be described.

[0055] The organometallic compound according to an embodiment of the present disclosure is a novel iridium coordination compound represented by the following Chemical Formula 1, wherein the main ligand and the auxiliary ligand connecting iridium (Ir) as the central coordination metal may be represented by L A and L B in Chemical Formula 1 below. In each of the main ligand and the auxiliary ligand, the dotted line of the 2-phenylpyridine moiety represents the bonding to the central metal Ir (iridium):

[0056] [Chemical Formula 1] Ir(L A ) m (L B ) n

[0057] Specifically, L A as the main ligand has a basic structure of a pyridine in which a polycyclic fused ring (hexagon-pentagon-hexagon-pentagon-hexagon) is connected to the pyridine of 2-phenylpyridine. L A as the main ligand can be divided into the following Chemical Formulas 2-1 to 2-3 based on two X orientations of the polycyclic fused ring:

[0058] [Chemical Formula 2-1]

[0059] [Chemical Formula 2-2]

[0060] [Chemical Formula 2-3]

[0061] wherein in each of Chemical Formulas 2-1 to 2-3,

[0062] X may represent one selected from the group consisting of O, S, NR7, and C(R8)(R9),

[0063] R 1-1 、R 1-2 、R 1-3 、R 1-4 、R 2-1 、R 2-2 、R 2-3 、R 2-4 、R 3-1 、R3-2 and R 3-3 and R 3-4 and R 4-1 and R 4-2 and R 4-3 each may independently represent one selected from the group consisting of: hydrogen, deuterium, a halogen atom, a C1-C30 alkyl group, a C3-C30 cycloalkyl group, a C1-C30 heteroalkyl group, a C7-C30 arylalkyl group, a C1-C30 alkoxy group, a C6-C30 aryloxy group, an amino group, a silyl group, a C2-C30 alkenyl group, a C3-C30 cycloalkenyl group, a C3-C30 heteroalkenyl group, a C2-C30 alkynyl group, a C6-C40 aryl group, a C3-C40 heteroaryl group, an acyl group, a carbonyl group, a carboxylic acid, an ester, a nitrile, an isonitrile, a sulfanyl group, a sulfinyl group, a sulfonyl group, a phosphino group, and combinations thereof,

[0064] R 1-1 and R 1-2 and R 1-3 and R 1-4 and R 2-1 and R 2-2 and R 2-3 and R 2-4 and R 3-1 and R 3-2 and R 3-3 and R 3-4 and R 4-1 and R 4-2 and R 4-3 and two adjacent substituents in R may be connected to each other to form a ring structure selected from the group consisting of: a substituted or unsubstituted C3-C20 cycloalkyl group, a substituted or unsubstituted C2-C20 heterocycloalkyl group, a substituted or unsubstituted C7-C20 arylalkyl group, a substituted or unsubstituted C2-C20 heteroarylalkyl group, a substituted or unsubstituted C3-C20 cycloalkenyl group, a substituted or unsubstituted C6-C30 aryl group, and a substituted or unsubstituted C3-C30 heteroaryl group,

[0065] R7, R8, and R9 each may independently represent one selected from the group consisting of: a C1-C30 alkyl group, a C3-C30 cycloalkyl group, a C1-C30 heteroalkyl group, a C7-C30 arylalkyl group, a C1-C30 alkoxy group, a C6-C30 aryloxy group, an amino group, a silyl group, a C2-C30 alkenyl group, a C3-C30 cycloalkenyl group, a C3-C30 heteroalkenyl group, a C2-C30 alkynyl group, a C6-C40 aryl group, and a C3-C40 heteroaryl group.

[0066] In addition, L as an auxiliary ligand B may be a bidentate ligand and may be represented by the following Chemical Formula 3:

[0067] [Chemical Formula 3]

[0068] In Chemical Formula 3,

[0069] R 5-1 、R 5-2 、R 5-3 、R 5-4 、R 6-1 、R 6-2 、R 6-3 and R 6-4 each independently may represent one selected from the group consisting of hydrogen, deuterium, C1-C5 linear alkyl, and C1-C5 branched alkyl, wherein the C1-C5 linear alkyl or C1-C5 branched alkyl may be substituted with at least one selected from deuterium and halogen,

[0070] R 5-1 、R 5-2 、R 5-3 、R 5-4 、R 6-1 、R 6-2 、R 6-3 and R 6-4 and two adjacent substituents among them may be connected to each other to form one ring structure selected from the group consisting of: substituted or unsubstituted C3-C20 cycloalkyl, substituted or unsubstituted C2-C20 heterocycloalkyl, substituted or unsubstituted C7-C20 arylalkyl, substituted or unsubstituted C2-C20 heteroarylalkyl, substituted or unsubstituted C3-C20 cycloalkenyl, substituted or unsubstituted C6-C30 aryl, and substituted or unsubstituted C3-C30 heteroaryl.

[0071] In Chemical Formula 1, m may be 1, 2, or 3, n may be 0, 1, or 2, and the sum of m and n may be 3.

[0072] The organometallic compound according to an embodiment of the present disclosure may have a heteroleptic or homoleptic structure. For example, the organometallic compound according to an embodiment of the present disclosure may have a heteroleptic structure in which m is 1 and n is 2 in Chemical Formula 1; or a heteroleptic structure in which m is 2 and n is 1; or a homoleptic structure in which m is 3 and n is 0.

[0073] Specific examples of the compound represented by Chemical Formula 1 according to the present disclosure may include one selected from the group consisting of the following Compounds 1 to 20. However, the specific examples of the compound represented by Chemical Formula 1 according to the present disclosure are not limited thereto, as long as it satisfies the above limitations of Chemical Formula 1:

[0074]

[0075] Reference Figure 1, an organic light-emitting device 100 according to an embodiment of the present disclosure may include a first electrode 110, a second electrode 120 facing the first electrode 110, and a light-emitting stack disposed between the first electrode 110 and the second electrode 120, wherein the light-emitting stack includes an organic layer 130. The organic layer 130 may include a hole transport layer (HTL) 150 and a red light-emitting layer 160, wherein the hole transport layer 150 may include a hole transport material, and the red light-emitting layer 160 may include a red host 160' and a red dopant 160" doped therein.

[0076] In particular, in the present disclosure, the red light-emitting layer 160 may contain not only the red host 160' and the red dopant 160", but also a charge scavenger 160"'. Therefore, as described above, triplet exciton quenching (TPQ) and decay occurring at the interface between the hole transport layer and the light-emitting layer and / or inside the light-emitting layer (EML) can be reduced or suppressed. Thus, the present disclosure is completed.

[0077] Specifically, in the prior art, generally, the light-emitting layer contains a host material and a dopant material doped therein. However, according to the present disclosure, a material that causes exciton quenching is additionally doped into the light-emitting layer, thereby reducing or suppressing the decay phenomenon and the TPQ phenomenon of the dopant material. In this regard, the material that causes exciton quenching to reduce or suppress the decay phenomenon and the TPQ phenomenon of the dopant material is referred to as the charge scavenger 160"'.

[0078] That is, when the host 160' of the light-emitting layer 160 is doped with the dopant 160" and the charge scavenger 160"', the following effects can be achieved.

[0079] i) The holes of the dopant 160" injected from the hole transport layer 150 into the light-emitting layer 160 can be captured by the charge scavenger 160"', thereby reducing the accumulation of holes at the interface between the hole transport layer 150 and the light-emitting layer 160, so that the TPQ phenomenon of the dopant 160" occurring at the interface can be reduced, thereby improving the efficiency and lifetime of the organic light-emitting diode.

[0080] ii) The charge scavenger 160"' can cause the quenching phenomenon of excitons inside the light-emitting layer 160, thereby reducing the TPQ phenomenon of the dopant 160" occurring inside the light-emitting layer 160. In an organic light-emitting diode including a tandem structure as described below, the charge scavenger 160"' can control the color shift according to the current density, so that the efficiency and lifetime of the organic light-emitting diode can be improved, and the decay phenomenon can also be reduced.

[0081] In order for the charge scavenger to exhibit the above-described effects, it is preferable that the red dopant, the charge scavenger, and the hole transport layer material of the organic light-emitting diode according to the present disclosure satisfy the following condition (1).

[0082] [Condition (1)]: |HOMO (RD) | ≤ |HOMO (CS) | ≤ |HOMO (HTL) |

[0083] In Condition (1), |HOMO (RD) | represents the absolute value of the HOMO energy level of the red dopant, |HOMO (CS) | represents the absolute value of the HOMO energy level of the charge scavenger, and |HOMO (HTL) | represents the absolute value of the HOMO energy level of the hole transport material.

[0084] When the absolute value of the HOMO energy level of the charge scavenger 160"' satisfies Condition (1), the holes of the dopant 160" injected from the hole transport layer 150 into the light-emitting layer 160 are captured by the charge scavenger 160"', thereby reducing the TPQ phenomenon.

[0085] According to the present disclosure, it is preferred that the red dopant and the charge scavenger of the organic light-emitting diode further satisfy the following Condition (2).

[0086] [Condition (2)]: T 1(RD) < T 1(CS)

[0087] In Condition (2), T 1(RD) represents the triplet energy level of the red dopant, and T 1(CS) represents the triplet energy level of the charge scavenger.

[0088] The charge scavenger 160"' is doped into the host 160' of the light-emitting layer 160 and participates in light emission together with the red dopant 160", thus shifting the color coordinates of the light-emitting layer, thereby reducing the target color rendering accuracy. In addition, in this case, it is difficult to reduce or suppress the TPQ phenomenon. Therefore, it is desirable to satisfy Condition (2) so that the triplet energy level value of the charge scavenger 160"' is higher than the triplet energy level value of the red dopant 160", so that energy transfer from the charge scavenger 160"' to the red dopant 160" may occur.

[0089] In addition, in order to enable the red light-emitting layer 160 to satisfy Condition (2) simultaneously, it is preferred that T 1(RD) can be in the range of 1.8 to 2.2 eV, and T 1(CS) can be lower than or equal to 2.6 eV. More preferably, T 1(RD) can be in the range of 1.8 to 2.0 eV, and T 1(CS) can be lower than or equal to 2.4 eV. Most preferably, T 1(RD) can be in the range of 1.9 to 2.0 eV, and T 1(CS)It can be lower than or equal to 2.3 eV.

[0090] According to the present disclosure, in order to improve the light-emitting efficiency of the diode, a red light-emitting layer 160 can be formed by doping a red dopant 160" and a charge scavenger 160"' into a red host 160'.

[0091] Preferably, based on the total weight of the red host 160', the doping concentration of each of the red dopant 160" and the charge scavenger 160"' can be in the range of 1 to 30 wt%. For example, based on the total weight of the red host 160', the doping concentration of each of the red dopant 160" and the charge scavenger 160"' can be in the range of 3 to 20 wt%, such as 5 to 15 wt%, such as 5 to 10 wt%, such as 3 to 8 wt%, such as 3 to 5 wt%. The present disclosure is not limited thereto, and the doping concentration of each of the red dopant and the charge scavenger can be adjusted based on the type of materials used.

[0092] In addition, in the present disclosure, based on the results of sufficient research, it is experimentally determined that the doping concentration of the charge scavenger 160" can be less than twice the doping concentration of the red dopant 160".

[0093] As described above, the charge scavenger can be doped into the light-emitting layer and can act as a light-emitting dopant. Therefore, when the doping concentration of the charge scavenger is greater than or equal to twice the doping concentration of the red dopant, the desired red light-emitting layer cannot be achieved. Although the red dopant is doped therein, the chromaticity coordinate system (CIEx, CIEy) may shift, such that the color of the emitted light is greenish.

[0094] Specifically, the chromaticity coordinate system of the red light-emitting layer obtained when increasing the doping concentration of the charge scavenger is compared with the chromaticity coordinate system (CIEx, CIEy) of the red light-emitting layer in which no charge scavenger is doped. Therefore, due to the large difference from the reference chromaticity coordinate system, it is difficult to present the target color of the emitted light. For example, when the absolute value of the change amount of CIEx or CIEy is greater than 0.004 to 0.005, the color of the light emitted from the actually manufactured diode tends to be greenish. In particular, CIEx can be a more important factor for color rendering in the red light-emitting layer.

[0095] Therefore, the charge scavenger 160"' can be doped into the host, such that the TPQ and attenuation phenomena can be suppressed or reduced, thereby improving the efficiency of the organic light-emitting diode. In particular, when considering color rendering, it is preferable to adjust the doping concentration of the charge scavenger 160"' to be less than twice the doping concentration of the red dopant 160".

[0096] The organic light-emitting diode according to the present disclosure includes the features of the present disclosure as described above. Figure 1The organic layer 130 disposed between the first electrode 110 and the second electrode 120 of the organic light-emitting diode 100 may be embodied as a stack formed by sequentially laminating a hole injection layer (HIL) 140, a hole transport layer (HTL) 150, a light-emitting layer (EML) 160, an electron transport layer (ETL) 170, and an electron injection layer (EIL) on the first electrode 110. The second electrode 120 may be formed on the electron injection layer 180, and a protective layer (not shown) may be formed thereon.

[0097] According to the present disclosure, the respective thicknesses of each layer included in the first electrode 110, the second electrode 120, and the organic layer 130 are not particularly limited and may be adjusted as needed. For example, the thickness of each of the first electrode 110 and the second electrode 120 may be in the range of 50 - 200 nm, the thickness of the hole injection layer 140 may be in the range of 5 - 10 nm, the thickness of the hole transport layer 150 may be in the range of 5 - 130 nm, the thickness of the light-emitting layer 160 may be in the range of 5 - 50 nm, the thickness of the electron transport layer 170 may be in the range of 5 - 50 nm, and the thickness of the electron injection layer 180 may be in the range of 5 - 50 nm.

[0098] In addition, although Figure 1 not shown in, a hole transport auxiliary layer may be further added between the hole transport layer 150 and the red light-emitting layer 160. The hole transport auxiliary layer may contain a compound having good hole transport characteristics and may reduce the difference in HOMO energy levels between the hole transport layer 150 and the light-emitting layer 160, thereby adjusting the hole injection characteristics. Therefore, the hole accumulation at the interface between the hole transport auxiliary layer and the light-emitting layer 160 can be reduced. Therefore, the deterioration of the diode can be reduced, so that the diode can be stabilized, thereby improving its efficiency and lifetime.

[0099] The first electrode 110 may be used as a positive electrode and may be made of ITO, IZO, tin oxide, or zinc oxide, which is a conductive material having a relatively large work function value. However, the present disclosure is not limited thereto.

[0100] The second electrode 120 may be used as a negative electrode and may include aluminum (Al), magnesium (Mg), calcium (Ca), or silver (Ag), which is a conductive material having a relatively small work function value, or an alloy or combination thereof. However, the present disclosure is not limited thereto.

[0101] The hole injection layer 140 may be located between the first electrode 110 and the hole transport layer 150. The hole injection layer 140 may have a function of improving the interfacial characteristics between the first electrode 110 and the hole transport layer 150, and may be selected from materials having suitable conductivity. The hole injection layer 140 may include a compound selected from the group consisting of secondary amine compounds, tertiary amine compounds, [n]radialene compounds, indacene compounds, metallophthalocyanine compounds, and combinations thereof. Specific examples thereof may include at least one selected from the group consisting of HATCN, MTDATA, TCTA, CuPc, TDAPB, PEDOT / PSS, N1,N1'-([1,1'-biphenyl]-4,4'-diyl)bis(N1,N4,N4-triphenylbenzene-1,4-diamine), and the like. Preferably, the hole injection layer 140 may include HATCN. However, the present disclosure is not limited thereto.

[0102] The hole transport layer 150 may be adjacent to the light-emitting layer and located between the first electrode 110 and the light-emitting layer 160. The material of the hole transport layer 150 may include a compound selected from the group consisting of TAPC, TPD, NPB, CBP, N-(biphenyl-4-yl)-9,9-dimethyl-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)-9H-fluorene-2-amine, N-(biphenyl-4-yl)-N-(4-(9-phenyl-9H-carbazol-3-yl)phenyl)biphenyl)-4-amine, and the like. Preferably, the material of the hole transport layer 150 may include TAPC or NPB. However, the present disclosure is not limited thereto.

[0103] The red light-emitting layer 160 according to the present disclosure may be embodied as a phosphorescent red light-emitting layer, and may contain a red host 160', a red dopant 160" doped in the red host 160', and a charge scavenger 160"'.

[0104] For example, any material used for the red host 160' in the art may be used as long as it can achieve the effects of the present disclosure. For example, the red host 160' according to the present disclosure may include one selected from the following: a compound containing a carbazolyl group, a tertiary amine compound, a compound containing a pyridyl group, a compound containing a pyrimidinyl group, and a compound containing a triazinyl group. More specifically, the red host 160' according to the present disclosure may include one selected from DMAC-BPP, PXZ-TRZ, DPTPCz, CBP, mCP (1,3-bis(carbazol-9-yl)), and the like. However, the present disclosure is not limited thereto. For example, any material used for the red host 160' in the art may be used as long as it can achieve the effects of the present disclosure.

[0105] In addition, for example, the red dopant 160" according to the present disclosure may preferably include a metal complex of iridium (Ir) or platinum (Pt) having a large atomic number. An iridium (Ir) metal complex is preferred. More specifically, the red dopant 160" may include a red doping material selected from the following: Ir(piq)3, Ir(piq)2(acac), Ir(2-phq)3, Ir(ppy)3, Ir(ppy)2(bpmp), Ir(ppz)3, Ir(piq)3, Ir(ppy)2(bpmp), etc. However, the present disclosure is not limited thereto. For example, the HOMO energy level of the red dopant 160" is preferably in the range of -5.5 to -4.8 (eV), and its T1 is preferably in the range of 1.8 to 2.2 (eV). The HOMO energy level and T1 of the red dopant 160" do not have to be limited thereto as long as those are applicable to the red light emitting layer.

[0106] According to the present disclosure, when selecting the material of the hole transport layer of the organic light emitting diode and the material of the red dopant of the red light emitting layer, the material of the charge scavenger 160"' can be selected as a material having a HOMO energy level that satisfies at least the above condition (1). In addition, it is more preferable to select a material having a HOMO energy level and a triplet energy level that simultaneously satisfy conditions (1) and (2) as the material of the charge scavenger 160"'. Therefore, a material that satisfies condition (1) or simultaneously satisfies conditions (1) and (2) can be selected as the material of the charge scavenger 160"'.

[0107] According to a preferred aspect of the present disclosure, the charge scavenger may include, but is not limited to, an organometallic compound represented by the following Chemical Formula 1 of the present disclosure:

[0108] [Chemical Formula 1] Ir(L A ) m (L B ) n

[0109] Wherein in Chemical Formula 1, L A may be a main ligand represented by one selected from the group consisting of the following Chemical Formulas 2-1 to 2-3, and L B may be an auxiliary ligand represented by the following Chemical Formula 3:

[0110] [Chemical Formula 2-1]

[0111] [Chemical Formula 2-2]

[0112] [Chemical Formula 2-3]

[0113] [Chemical Formula 3]

[0114] The definitions of each of Chemical Formulas 1, 2-1, 2-2, 2-3, and 3 are the same as those described in the claims of the present disclosure and the above description.

[0115] In addition, the electron transport layer 170 and the electron injection layer 180 may be sequentially stacked between the red light emitting layer 160 and the second electrode 120. The material of the electron transport layer 170 needs to have a high electron mobility so that electrons can be stably supplied to the light emitting layer under smooth electron transport.

[0116] For example, the material of the electron transport layer 170 may include a compound selected from the group consisting of: Alq3 (tris(8-hydroxyquinoline)aluminum), Liq (lithium 8-hydroxyquinoline), PBD (2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole), TAZ (3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole), spiro-PBD, BAlq (bis(2-methyl-8-hydroxyquinoline)-4-(phenylphenoxy)aluminum), SAlq, TPBi (2,2',2-(1,3,5-benzenetriyl)-tris(1-phenyl-1H-benzoimidazole), oxadiazole, triazole, phenanthroline, benzoxazole, benzothiazole, ZADN (2-(4-(9,10-di(naphthalen-2-yl)anthracen-2-yl)phenyl)-1-phenyl-1H-benzo[d]imidazole), etc. Preferably, the material of the electron transport layer 170 may include ZADN. However, the present disclosure is not limited thereto.

[0117] The electron injection layer 180 is used to facilitate electron injection. The material of the electron injection layer may include a compound selected from the group consisting of Alq3 (tris(8-hydroxyquinoline)aluminum), PBD, TAZ, spiro-PBD, BAlq, SAlq, Bphen, etc. However, the present disclosure is not limited thereto. Alternatively, the electron injection layer 180 may include a mixture of an organic compound (or an organometallic compound) and a metal material, or may include only a metal material. For example, the electron injection layer 180 may include a mixture of Bphen and LiF.

[0118] In this regard, the metal material may include, for example, one or more selected from the group consisting of Liq, LiF, NaF, KF, RbF, CsF, FrF, BeF2, MgF2, CaF2, SrF2, BaF2, RaF2, etc. However, the present disclosure is not limited thereto. In addition, the material of the electron injection layer 180 may include a mixture of a metal material and a metal element with a low work function such as ytterbium (Yb), calcium (Ca), strontium (Sr), barium (Ba), lanthanum (La), etc. For example, a mixture of LiF and ytterbium (Yb) may be used as the material of the electron injection layer 180.

[0119] The organic light emitting diode according to the present disclosure may be embodied as a white light emitting diode having a tandem structure. The tandem organic light emitting diode according to an exemplary embodiment of the present disclosure may be formed in a structure in which adjacent light emitting stacks among two or more light emitting stacks are connected to each other through a charge generation layer (CGL). The organic light emitting diode may include at least two light emitting stacks disposed on a substrate, wherein each of the at least two light emitting stacks includes a first electrode and a second electrode facing each other, and a light emitting layer disposed between the first electrode and the second electrode to emit light in a specific wavelength band. The plurality of light emitting stacks may emit light of the same color or different colors. In addition, one or more light emitting layers may be included in one light emitting stack, and the plurality of light emitting layers may emit light of the same color or different colors.

[0120] Figure 2 and Figure 3 are cross-sectional views schematically showing an organic light emitting diode having two light emitting stacks in a tandem structure and an organic light emitting diode having three light emitting stacks in a tandem structure according to some embodiments of the present disclosure, respectively.

[0121] As Figure 2 shown, the organic light emitting diode 100 according to the present disclosure includes a first electrode 110 and a second electrode 120 facing each other, and an organic layer 230 disposed between the first electrode 110 and the second electrode 120. The organic layer 230 may be located between the first electrode 110 and the second electrode, and may include: a first light emitting stack ST1 including a first light emitting layer 261, a second light emitting stack ST2 located between the first light emitting stack ST1 and the second electrode 120 and including a second light emitting layer 262, and a charge generation layer CGL located between the first light emitting stack ST1 and the second light emitting stack ST2. The charge generation layer CGL may include an N-type charge generation layer 291 and a P-type charge generation layer 292. According to the present disclosure, at least one of the first light emitting layer 261 and the second light emitting layer 262 may be a red light emitting layer. The first light emitting stack ST1 may further include a first HTL 251 and a first ETL 271. The second light emitting stack ST2 may further include a second HTL 252 and a second ETL 272. In one embodiment, the first HTL 251 and the second HTL 252 may have a structure and material similar to or the same as that of the Figure 1 HTL 150. In one embodiment, the first ETL 271 and the second ETL 272 may have a structure and material similar to or the same as that of the Figure 1 ETL 170.

[0122] For example, as Figure 2As shown, the second light-emitting layer 262 of the second light-emitting stack ST2 may contain a host material 262', a red dopant 262", and a charge scavenger 262"', where the charge scavenger 262"' may include an organometallic compound represented by Chemical Formula 1 of the present disclosure.

[0123] Although Figure 2 not shown in, each of the first light-emitting stack ST1 and the second light-emitting stack ST2 may further include an additional light-emitting layer in addition to the first light-emitting layer 261 and the second light-emitting layer 262.

[0124] As Figure 3 shown, the organic light-emitting diode 100 according to the present disclosure includes a first electrode 110 and a second electrode 120 facing each other, and an organic layer 330 disposed between the first electrode 110 and the second electrode 120. The organic layer 330 may be located between the first electrode 110 and the second electrode 120, and may include: a first light-emitting stack ST1 including a first light-emitting layer 261, a second light-emitting stack ST2 including a second light-emitting layer 262, a third light-emitting stack ST3 including a third light-emitting layer 263, a first charge generation layer CGL1 located between the first light-emitting stack ST1 and the second light-emitting stack ST2, and a second charge generation layer CGL2 located between the second light-emitting stack ST2 and the third light-emitting stack ST3. The first charge generation layer CGL1 may include an N-type charge generation layer 291 and a P-type charge generation layer 292. The second charge generation layer CGL2 may include an N-type charge generation layer 293 and a P-type charge generation layer 294. At least one of the first light-emitting layer 261, the second light-emitting layer 262, and the third light-emitting layer 263 may be a red light-emitting layer according to the present disclosure. For example, as Figure 3 shown, the second light-emitting layer 262 of the second light-emitting stack ST2 may contain a host material 262', a red dopant 262", and a charge scavenger 262"', where the charge scavenger 262"' may include an organometallic compound represented by Chemical Formula 1 of the present disclosure. The first light-emitting stack ST1 may further include a first HTL 251 and a first ETL 271. The second light-emitting stack ST2 may further include a second HTL 252 and a second ETL 272. The third light-emitting stack ST3 may further include a third HTL 253 and a third ETL 273. In one embodiment, the first HTL 251, the second HTL 252, and the third HTL 253 may have a structure and material similar to or the same as that of Figure 1 the HTL 150. In one embodiment, the first ETL 271, the second ETL 272, and the third ETL 273 may have a structure and material similar to or the same as that of Figure 1 the ETL 170.

[0125] In addition, an organic light emitting diode according to an embodiment of the present disclosure may include a tandem structure in which four or more light emitting stacks and three or more charge generation layers are disposed between a first electrode and a second electrode.

[0126] The organic light emitting diode according to the present disclosure can be used as a light emitting element in each of an organic light emitting display device and a lighting device. In one embodiment, Figure 4 is a cross-sectional view schematically showing an organic light emitting display device including an organic light emitting diode according to some embodiments of the present disclosure as its light emitting element.

[0127] As Figure 4 shown, the organic light emitting display device 3000 includes a substrate 3010, an organic light emitting diode 4000, and a encapsulation film 3900 covering the organic light emitting diode 4000. A driving thin film transistor Td as a driving element and the organic light emitting diode 4000 connected to the driving thin film transistor Td are located on the substrate 3010.

[0128] Although Figure 4 not explicitly shown in, gate lines and data lines intersecting each other to define a pixel region, a power supply line extending in parallel with and spaced apart from one of the gate lines and the data lines, a switching thin film transistor connected to the gate lines and the data lines, and a storage capacitor connected to one electrode of the thin film transistor and the power supply line are further formed on the substrate 3010.

[0129] The driving thin film transistor Td is connected to the switching thin film transistor and includes a semiconductor layer 3100, a gate electrode 3300, a source 3520, and a drain 3540.

[0130] The semiconductor layer 3100 may be formed on the substrate 3010 and may be made of an oxide semiconductor material or polycrystalline silicon. When the semiconductor layer 3100 is made of an oxide semiconductor material, a light shielding pattern (not shown) may be formed under the semiconductor layer 3100. The light shielding pattern prevents incident light from entering the semiconductor layer 3100, thereby preventing the semiconductor layer 3100 from deteriorating due to light. Alternatively, the semiconductor layer 3100 may be made of polycrystalline silicon. In this case, two edges of the semiconductor layer 3100 may be doped with impurities.

[0131] A gate insulating layer 3200 made of an insulating material is formed above the entire surface of the substrate 3010 and on the semiconductor layer 3100. The gate insulating layer 3200 may be made of an inorganic insulating material such as silicon oxide or silicon nitride.

[0132] A gate electrode 3300 made of a conductive material such as metal is formed on the gate insulating layer 3200 and corresponds to the center of the semiconductor layer 3100. The gate electrode 3300 is connected to the switching thin film transistor.

[0133] An interlayer insulating layer 3400 made of an insulating material is formed over the entire surface of a substrate 3010 and on a gate electrode 3300. The interlayer insulating layer 3400 may be made of an inorganic insulating material such as silicon oxide or silicon nitride, or an organic insulating material such as benzocyclobutene or photo-acryl.

[0134] The interlayer insulating layer 3400 has a first semiconductor layer contact hole 3420 and a second semiconductor layer contact hole 3440 defined therein that respectively expose two opposite sides of the semiconductor layer 3100. The first semiconductor layer contact hole 3420 and the second semiconductor layer contact hole 3440 are respectively located on two opposite sides of the gate electrode 3300 and are spaced apart from the gate electrode 3300.

[0135] A source electrode 3520 and a drain electrode 3540 made of a conductive material such as metal are formed on the interlayer insulating layer 3400. The source electrode 3520 and the drain electrode 3540 are located around the gate electrode 3300 and are spaced apart from each other, and are respectively in contact with two opposite sides of the semiconductor layer 3100 through the first semiconductor layer contact hole 3420 and the second semiconductor layer contact hole 3440. The source electrode 3520 is connected to a power supply line (not shown).

[0136] The semiconductor layer 3100, the gate electrode 3300, the source electrode 3520, and the drain electrode 3540 constitute a driving thin film transistor Td. The driving thin film transistor Td has a coplanar structure in which the gate electrode 3300, the source electrode 3520, and the drain electrode 3540 are located above the semiconductor layer 3100.

[0137] Alternatively, the driving thin film transistor Td may have an inverted staggered structure in which the gate electrode is disposed below the semiconductor layer and the source and drain electrodes are disposed above the semiconductor layer. In this case, the semiconductor layer may be made of amorphous silicon. In one embodiment, a switching thin film transistor (not shown) may have a structure substantially the same as that of the driving thin film transistor (Td).

[0138] In one example, the organic light emitting display device 3000 may include a color filter 3600 that absorbs light generated by an electroluminescent element (light emitting diode) 4000. For example, the color filter 3600 may absorb red (R) light, green (G) light, blue (B) light, and white (W) light. In this case, the red, green, and blue color filter patterns that absorb light may be independently formed in different pixel regions. Each of these color filter patterns may be arranged to overlap with respective organic layers 4300 of the organic light emitting diode 4000, thereby emitting light corresponding to the wavelength band of each color filter. Employing the color filter 3600 may allow the organic light emitting display device 3000 to achieve full color.

[0139] For example, when the organic light-emitting display device 3000 is a bottom-emitting type, the light-absorbing color filter 3600 may be located on a part of the interlayer insulating layer 3400 corresponding to the organic light-emitting diode 4000. In an optional embodiment, when the organic light-emitting display device is a top-emitting type, the color filter may be located above the organic light-emitting diode 4000, that is, above the second electrode 4200. For example, the color filter 3600 may be formed to have a thickness of 2-5 μm.

[0140] In one example, a protective layer 3700 having a drain contact hole 3720 defined therein is formed to cover the driving thin-film transistor Td, and the drain contact hole 3720 exposes the drain 3540 of the driving thin-film transistor Td.

[0141] On the protective layer 3700, respective first electrodes 4100 connected to the drain 3540 of the driving thin-film transistor Td through the drain contact hole 3720 are respectively formed in each pixel region.

[0142] The first electrode 4100 may serve as a positive electrode (anode), and may be made of a conductive material having a relatively large work function value. For example, the first electrode 4100 may be made of a transparent conductive material such as ITO, IZO, or ZnO.

[0143] In one example, when the organic light-emitting display device 3000 is a top-emitting type, a reflective electrode or a reflective layer may be further formed under the first electrode 4100. For example, the reflective electrode or the reflective layer may be made of one of aluminum (Al), magnesium (Mg), silver (Ag), nickel (Ni), and an aluminum-palladium-copper (APC) alloy.

[0144] A bank layer 3800 covering the edge of the first electrode 4100 is formed on the protective layer 3700. The bank layer 3800 exposes the center of the first electrode 4100 corresponding to the pixel region.

[0145] An organic layer 4300 is formed on the first electrode 4100. If necessary, the organic light-emitting diode 4000 may have a series structure. For the series structure, reference may be made to Figures 2 to 4 and their descriptions above.

[0146] The second electrode 4200 is formed on the substrate 3010 on which the organic layer 4300 has been formed. The second electrode 4200 is disposed above the entire surface of the display region, and is made of a conductive material having a relatively small work function value, and may serve as a negative electrode (cathode). For example, the second electrode 4200 may be made of one of aluminum (Al), magnesium (Mg), and an aluminum-magnesium alloy (Al-Mg).

[0147] The first electrode 4100, the organic layer 4300, and the second electrode 4200 constitute the organic light-emitting diode 4000.

[0148] The encapsulation film 3900 is formed on the second electrode 4200 to prevent external moisture from infiltrating into the organic light-emitting diode 4000. Although Figure 4 not explicitly shown in [], the encapsulation film 3900 may have a three-layer structure in which a first inorganic layer, an organic layer, and an inorganic layer are sequentially stacked. However, the present disclosure is not limited thereto.

[0149] Hereinafter, preparation examples of the present disclosure and embodiments of the present application will be described. However, the following embodiments of the present application are merely an example of the present disclosure. The present disclosure is not limited thereto.

[0150] Preparation Example of Ligand

[0151] (1) Preparation of Ligand A

[0152] Step 1) Preparation of Ligand A-3

[0153]

[0154] In a 500 ml round-bottom flask, under a nitrogen atmosphere, compound SM-1 (6.12 g, 20 mmol), compound SM-2 (3.04 g, 20 mmol), Pd(PPh3)4 (1.2 g, 1 mmol), and K2CO3 (8.3 g, 60 mmol) were dissolved in a mixture of 200 ml of toluene and 50 ml of water, and the mixed solution was stirred under reflux for 12 hours. The organic layer was extracted therefrom with chloroform and washed with water. Water was removed therefrom with anhydrous magnesium sulfate, the resulting product was filtered through a filter, and the organic solvent was distilled off under reduced pressure, followed by column purification to obtain compound A-3 (6.35 g, yield: 88%).

[0155] Step 2) Preparation of Ligand A-2

[0156]

[0157] Under a nitrogen atmosphere, compound A-3 (7.22 g, 20 mmol), 1 M BBr3 (46 ml, 46 mmol), and CH2Cl2 (300 ml) were added to a 500 ml round-bottom flask, the mixture was stirred at 0 °C for 8 hours, and the reaction occurred overnight at room temperature. After the reaction was completed, the reaction product was neutralized with a saturated aqueous NaHCO3 solution. The sample was transferred to a separatory funnel, extracted with CH2Cl2, and purified by column chromatography to prepare compound A-2 (5.93 g, yield: 89%).

[0158] Step 3) Preparation of Ligand A-1

[0159]

[0160] Under a nitrogen atmosphere, compound A-2 (6.66 g, 20 mmol), K2CO3 (6.07 g, 44 mmol) and NMP (200 ml) were charged into a 500 ml round-bottom flask. The mixture was stirred at 150 °C for 8 hours and then cooled to room temperature. The sample was transferred to a separatory funnel, water (200 ml) was added thereto, and extraction was performed with AcOEt. The sample was purified by column chromatography. Compound A-1 (5.16 g, yield: 88%) was thus obtained.

[0161] Step 4) Preparation of ligand A

[0162]

[0163] In a 500 ml round-bottom flask, under a nitrogen atmosphere, compound A-1 (5.86 g, 20 mmol), compound SM (3.98 g, 20 mmol), Pd(PPh3)4 (2.3 g, 2 mmol), P(t-Bu)3 (0.81 g, 4 mmol) and NaOtBu (7.7 g, 80 mmol) were dissolved in 200 ml of toluene, and the mixed solution was stirred under reflux for 12 hours. The organic layer was extracted therefrom with chloroform and washed with water. Water was removed therefrom with anhydrous magnesium sulfate, the resulting product was filtered through a filter, and the organic solvent was distilled off under reduced pressure, followed by column purification, thereby obtaining compound A (7.33 g, yield: 89%).

[0164] (2) Preparation of ligand B

[0165]

[0166] BB (5.16 g, 4.8 mmol), silver trifluoromethanesulfonate (AgOTf, 3.6 g, 14.3 mmol) and dichloromethane were charged into a 1000 ml round-bottom flask, and the mixture was stirred at room temperature for 16 hours to carry out the reaction. After the reaction was completed, the solid was removed therefrom by filtration using celite. The solvent was distilled off under reduced pressure. The resulting solid compound B (6.03 g, yield: 88%) was thus obtained.

[0167] (3) Preparation of ligand C

[0168]

[0169] Compound SM-3 (6.04 g, 20 mmol), compound SM-4 (4.68 g, 20 mmol), Pd(PPh3)4 (1.2 g, 1 mmol) and K2CO3 (8.3 g, 60 mmol) were dissolved in a mixture of 200 ml of toluene and 50 ml of water, and the mixed solution was stirred under reflux for 12 hours. The organic layer was extracted therefrom with chloroform and washed with water. Water was removed therefrom with anhydrous magnesium sulfate, and the resulting product was filtered through a filter, and the organic solvent was distilled off under reduced pressure, and then column purification was carried out to obtain compound C (7.48 g, yield: 91%).

[0170] <Preparation Example of Organometallic Compound>

[0171] Preparation of Compound 1

[0172]

[0173] In a 100 ml round-bottom flask, under a nitrogen atmosphere, iridium precursor B (2.15 g, 3.5 mmol) and ligand A (1.44 g, 3 mmol) were dissolved in a mixed solvent (2-ethoxyethanol:DMF = 40 ml:40 ml), and the mixed solution was stirred at 130 °C for 48 hours to carry out the reaction. After the reaction was completed, the organic layer was extracted therefrom with dichloromethane and distilled water, and the solvent was removed therefrom by distillation under reduced pressure. Column chromatography was carried out on the crude product using toluene:hexane to obtain compound 1 (2.57 g, yield: 94%).

[0174] Preparation of Compound 13

[0175]

[0176] In a 100 ml round-bottom flask, under a nitrogen atmosphere, iridium precursor B (2.15 g, 3.5 mmol) and ligand C (1.44 g, 3 mmol) were dissolved in a mixed solvent (2-ethoxyethanol:DMF = 40 ml:40 ml), and the mixed solution was stirred at 130 °C for 48 hours to carry out the reaction. After the reaction was completed, the organic layer was extracted therefrom with dichloromethane and distilled water, and the solvent was removed by distillation under reduced pressure. Column chromatography was carried out on the crude product using toluene:hexane to obtain compound 13 (2.48 g, yield: 83%).

[0177] <Examples of the Present Application>

[0178] 1. Manufacture of Organic Light-Emitting Diode

[0179] Wash the one with a coating thickness of A glass substrate of ITO (indium tin oxide) thin film is then ultrasonically cleaned with solvents such as isopropyl alcohol, acetone, and methanol. Then, the glass substrate is dried. In this way, an ITO transparent electrode is formed. HATCN, which is a hole injection material, is deposited on the ITO transparent electrode by thermal vacuum deposition. In this way, a hole injection layer with a thickness of 10 nm is formed. Then, NPB, which is a hole transport material, is deposited on the hole injection layer by thermal vacuum deposition. In this way, a hole transport layer with a thickness of 30 nm is formed.

[0180] Then, DMAC-BPP, which is the host material of the red light emitting layer, is deposited on the hole transport layer by thermal vacuum deposition. Ir(piq)2(acac), which is a dopant, is doped into the host material at a doping concentration of 5%. Compound 1, which is a charge scavenger, is doped into the host material at a doping concentration of 3%. In this way, a red light emitting layer with a thickness of 20 nm is formed.

[0181] ZADN (thickness: 25 nm), which is an electron transport material, is deposited on the red light emitting layer by thermal vacuum deposition. Then, BPhen+Li (thickness: 20 nm), which is an electron injection material, is deposited on the electron transport layer by thermal vacuum deposition. Then, aluminum with a thickness of 100 nm is deposited thereon to form a negative electrode. An organic light emitting diode is fabricated in this way.

[0182] 2. Performance testing of the organic light emitting diode

[0183] Data regarding the fabricated organic light emitting diode are recorded and calculated as follows.

[0184] 1) Each of CIEx and CIEy is recorded according to the CIE 1931 chromaticity coordinate system.

[0185] 2) Using a luminance meter, the external quantum efficiency (EQE, %) is measured at a current density of 10 mA / cm 2 .

[0186] 3) The EQE is measured at current densities in the range of 0.25 mA / cm 2 to 100 mA / cm 2 . Then, the normalized EQE at each current density based on the EQE at 0.25 mA / cm 2 is calculated.

[0187] 4) According to Equation 1 below, the decay value is calculated based on the normalized EQE values at 0.25 mA / cm 2 and 100 mA / cm 2 respectively:

[0188] [Equation 1]

[0189]

[0190] The meaning of Equation 1 refers to the percentage of the ratio of the EQE at a high gray level (100 mA / cm 2 ) to the EQE at a low gray level (0.25 mA / cm 2 ). The attenuation value is set as the rate at which the EQE decreases as the current density value increases.

[0191] In addition, when the attenuation value (%) in each experimental group is greater than the reference value, this indicates a reduction in the attenuation phenomenon.

[0192] <Experimental Group 1>: Comparative Examples 1-1 to 1-3 and Examples 1-1 to 1-2 of the present application

[0193] Except for the materials of the charge scavenger and the HTL used as shown in Table 1 below, the organic light-emitting diodes are fabricated in the same manner as in Part 1 of <Examples of the present application> described above. That is, Comparative Example 1-1 does not include a charge scavenger. Comparative Examples 1-2 and 1-3 use Ir(ppy)2(acac) and FIrPic instead of Compound 1 as the charge scavenger, respectively. Examples 1-1 and 1-2 of the present application use Compound 1 and 13 as the charge scavenger, respectively. (That is, <Examples of the present application> described above corresponds to Example 1-1 of the present application in Experimental Group 1.)

[0194] In the same manner as in Part 2 of <Examples of the present application> described above, the performance tests of the organic light-emitting diodes of Comparative Examples 1-1 to 1-3 and Examples 1-1 to 1-2 of the present application are carried out. The test results are described in Table 2. In Experimental Group 1, the test result value of Comparative Example 1-1 is set as the reference value.

[0195] Table 1

[0196]

[0197]

[0198] The HOMO level of Ir(piq)2(acac) is in the range of -5.0 (eV) to -5.1 (eV), and its T1 is 2.00 (eV).

[0199] The HOMO level of Ir(ppy)2(acac) is -4.95 (eV), and its T1 is 2.47 (eV).

[0200] The HOMO level of FIrPic is -5.6 (eV), and its T1 is 2.65 (eV).

[0201] The HOMO energy level of Compound 1 is -5.12 (eV), and its T1 is 2.25 (eV).

[0202] The HOMO energy level of Compound 13 is -5.12 (eV), and its T1 is 1.95 (eV).

[0203] The HOMO energy level of TAPC is -5.5 (eV).

[0204] Table 2

[0205]

[0206] From the results of Table 1 and Table 2, it can be seen that when each of Examples 1-1 and 1-2 of the present application in which the light-emitting layer is doped with a charge scavenger satisfying the condition (1) of the present disclosure or simultaneously satisfying the conditions (1) and (2) is compared with Comparative Example 1-1, a red light-emitting layer of each of Examples 1-1 and 1-2 of the present application is realized, such that the EQE (%) of each of Examples 1-1 and 1-2 of the present application increases and its decay value increases. On the contrary, the EQE (%) of each of Comparative Examples 1-2 and 1-3 in which the light-emitting layer is doped with a charge scavenger not satisfying the conditions (1) and (2) is lower than the EQE (%) of Comparative Example 1-1 in which the light-emitting layer is not doped with a charge scavenger, and the decay values of Comparative Examples 1-2 and 1-3 are smaller than the decay value of Comparative Example 1-1, resulting in a deteriorated result.

[0207] <Experimental Group 2>: Comparative Examples 2-1 to 2-3 and Examples 2-1 to 2-2 of the present application

[0208] Except for using the materials of the dopant, the charge scavenger, and the HTL as shown in Table 3 below, an organic light-emitting diode was fabricated in the same manner as in 1. of <Examples of the present application> described above.

[0209] That is, in Comparative Examples 2-1 to 2-3 and Examples 2-1 to 2-2 of the present application, the material of the dopant is Ir(2-phq)3 instead of Ir(piq)2(acac). Comparative Example 2-1 does not include a charge scavenger. Comparative Examples 2-2 and 2-3 use Ir(ppy)2(acac) and FIrPic instead of Compound 1 as the charge scavenger, respectively. Examples 2-1 and 2-2 of the present application use Compound 1 and 13 as the charge scavenger, respectively.

[0210] In the same manner as in 2. of <Examples of the present application> described above, a performance test of each of the organic light-emitting diodes of Comparative Examples 2-1 to 2-3 and Examples 2-1 to 2-2 of the present application was conducted. The test results are described in Table 4. In Experimental Group 2, the test result value of Comparative Example 2-1 was set as the reference value.

[0211] Table 3

[0212] Example Host Dopant Charge scavenger HTL Comparative Example 2-1 DMAC-BPP <![CDATA[Ir(2-phq)3]]> - TAPC Comparative Example 2-2 DMAC-BPP <![CDATA[Ir(2-phq)3]]> <![CDATA[Ir(ppy)2(acac)]]> TAPC Comparative Example 2-3 DMAC-BPP <![CDATA[Ir(2-phq)3]]> FIrPic TAPC Example 2-1 of the present application DMAC-BPP <![CDATA[Ir(2-phq)3]]> Compound 1 TAPC Example 2-2 of the present application DMAC-BPP <![CDATA[Ir(2-phq)3]]> Compound 13 TAPC

[0213] The HOMO energy level of Ir(2-phq)3 is 5.1 (eV), and its T1 is 2.00 (eV).

[0214] The energy levels of Ir(ppy)2(acac), FIrPic, Compound 1, Compound 13, and TAPC are the same as those described above.

[0215] Table 4

[0216]

[0217] As can be seen from the results of Table 3 and Table 4, when each of Examples 2-1 and 2-2 of the present application in which the light-emitting layer is doped with a charge scavenger satisfying the condition (1) of the present disclosure or simultaneously satisfying the conditions (1) and (2) is compared with Comparative Example 2-1, the red light-emitting layers of each of Examples 2-1 and 2-2 of the present application are realized, such that the EQE (%) of each of Examples 2-1 and 2-2 of the present application increases and its decay value increases. On the contrary, the EQE (%) of each of Comparative Examples 2-2 and 2-3 in which the light-emitting layer is doped with a charge scavenger not satisfying the conditions (1) and (2) is lower than the EQE (%) of Comparative Example 2-1 in which the light-emitting layer is not doped with a charge scavenger, and the decay values of Comparative Examples 2-2 and 2-3 are smaller than the decay value of Comparative Example 2-1, resulting in deteriorated results.

[0218] <Experimental Group 3>: Refer to Comparative Example 1 and Reference Experimental Examples 1 to 10

[0219] Except for the materials of the dopant, the charge scavenger, and the HTL as shown in Table 5 below, an organic light-emitting diode is manufactured in the same manner as in 1. of <Examples of the Present Application> described above. That is, Comparative Example 1 does not contain a charge scavenger. While increasing the doping concentration of Compound 1 doped as a charge scavenger from 1% to 10% at 1%, an organic light-emitting diode is manufactured (Reference Experimental Examples 1 to 10).

[0220] In the same manner as in part 2 of <Examples of the Present Application> described above, a performance test of the organic light-emitting diode of each of Comparative Example 1 and Reference Experimental Examples 1 to 10 is performed. The test results are described in Table 6. In Experimental Group 3, the test result value of Comparative Example 1 is set as a reference value.

[0221] Table 5

[0222] Example Host Dopant (5%) Charge scavenger (doping concentration) HTL Reference Comparative Example 1 DMAC-BPP <![CDATA[Ir(piq)2(acac)]]> - TAPC Reference Experimental Example 1 DMAC-BPP <![CDATA[Ir(piq)2(acac)]]> Compound 1 (1%) TAPC Reference Experimental Example 2 DMAC-BPP <![CDATA[Ir(piq)2(acac)]]> Compound 1 (2%) TAPC Reference Experimental Example 3 DMAC-BPP <![CDATA[Ir(piq)2(acac)]]> Compound 1 (3%) TAPC Reference Experimental Example 4 DMAC-BPP <![CDATA[Ir(piq)2(acac)]]> Compound 1 (4%) TAPC Reference Experimental Example 5 DMAC-BPP <![CDATA[Ir(piq)2(acac)]]> Compound 1 (5%) TAPC Reference Experimental Example 6 DMAC-BPP <![CDATA[Ir(piq)2(acac)]]> Compound 1 (6%) TAPC Reference Experimental Example 7 DMAC-BPP <![CDATA[Ir(piq)2(acac)]]> Compound 1 (7%) TAPC Reference Experimental Example 8 DMAC-BPP <![CDATA[Ir(piq)2(acac)]]> Compound 1 (8%) TAPC Reference Experimental Example 9 DMAC-BPP <![CDATA[Ir(piq)2(acac)]]> Compound 1 (9%) TAPC Reference Experimental Example 10 DMAC-BPP <![CDATA[Ir(piq)2(acac)]]> Compound 1 (10%) TAPC

[0223] Table 6

[0224]

[0225] As can be seen from the results in Tables 5 and 6, when Compound 1 that satisfies conditions (1) and (2) of the present disclosure is used as a charge scavenger doped into the red light-emitting layer, and even when its doping concentration is only 1%, Reference Experimental Example 1 has a greater EQE (%) and decay value compared to Reference Comparative Example 1 in which the charge scavenger is not doped into the red light-emitting layer.

[0226] However, compared to Reference Comparative Example 1, Reference Experimental Example 10 in which the doping concentration (10%) of the charge scavenger is twice the doping concentration (5%) of the dopant has a difference of 0.004 in terms of CIEx and a difference of 0.005 in terms of CI Ey, respectively. Therefore, in fact, it can be seen that the color of the light emitted from the organic light-emitting diode of Reference Experimental Example 10 is greenish. Therefore, it can be determined that when the doping concentration of the charge scavenger is greater than or equal to twice the doping concentration of the dopant, the accurate target red color is not presented.

[0227] The protection scope of the present disclosure shall be interpreted by the scope of the claims, and all technical concepts within the equivalent scope thereof shall be interpreted as being included within the scope of the present disclosure. Although the embodiments of the present disclosure have been described in more detail with reference to the accompanying drawings, the present disclosure is not necessarily limited to these embodiments. The present disclosure can be implemented in various modified ways without departing from the technical concept of the present disclosure. Therefore, the embodiments disclosed in the present disclosure are not intended to limit the technical concept of the present disclosure, but only to describe the present disclosure. The scope of the technical concept of the present disclosure is not limited to the described embodiments. Therefore, it should be understood that the above-described embodiments are exemplary in all aspects and not restrictive. The protection scope of the present disclosure shall be interpreted by the claims, and all technical concepts within the scope of the present disclosure shall be interpreted as being included within the scope of the present disclosure.

Claims

1. An organic light-emitting device, comprising: A first electrode; A second electrode facing the first electrode; and An emission stack disposed between the first electrode and the second electrode, Wherein the emission stack includes an organic layer, Wherein the organic layer includes a hole transport layer and a red emission layer, Wherein the hole transport layer includes a hole transport material, Wherein the red emission layer includes a red host, a red dopant, and a charge scavenger, Wherein the charge scavenger includes an organometallic compound selected from Compound 1 and Compound 13:

2. The organic light-emitting device according to claim 1, wherein the device satisfies the following condition (1): [Condition (1)]: |HOMO (RD) | ≤ |HOMO (CS) | ≤ |HOMO (HTL) | Among them, in condition (1), |HOMO (RD) | represents the absolute value of the HOMO energy level of the red dopant, and |HOMO (CS) | represents the absolute value of the HOMO energy level of the charge scavenger, and |HOMO (HTL) | represents the absolute value of the HOMO energy level of the hole transport material.

3. The organic light-emitting device according to claim 1, wherein the organic light-emitting device further satisfies the following condition (2): [Condition (2)]: T 1(RD) <T 1(CS) Among them, in condition (2), T 1(RD) represents the triplet energy level of the red dopant, and T 1(CS) represents the triplet energy level of the charge scavenger.

4. The organic light-emitting device according to claim 3, wherein T 1(RD) is in the range of 1.8 eV to 2.2 eV, wherein T 1(CS) is less than or equal to 2.6 eV.

5. The organic light-emitting device according to claim 1, wherein based on the total weight of the red host, the doping concentration of the red dopant is in the range of 1-30 wt%. Wherein based on the total weight of the red host, the doping concentration of the charge scavenger is in the range of 1-30 wt%.

6. The organic light-emitting device according to claim 5, wherein the doping concentration of the charge scavenger is less than twice the doping concentration of the red dopant.

7. The organic light-emitting device according to claim 1, wherein the organic layer further includes at least one of a hole injection layer, an electron transport layer, or an electron injection layer.

8. An organic light-emitting device, comprising: A first electrode; A second electrode facing the first electrode; and A first emission stack and a second emission stack located between the first electrode and the second electrode, Wherein each of the first emission stack and the second emission stack includes at least one emission layer, Wherein at least one emission layer of at least one of the first emission stack or the second emission stack includes a red emission layer, Wherein the red emission layer includes a red host, a red dopant, and a charge scavenger, Wherein the charge scavenger includes an organometallic compound selected from Compound 1 and Compound 13:

9. An organic light-emitting device, comprising: A first electrode; A second electrode facing the first electrode; and A first emission stack, a second emission stack, and a third emission stack located between the first electrode and the second electrode, Wherein each of the first emission stack, the second emission stack, and the third emission stack includes at least one emission layer, Wherein at least one emission layer of at least one of the first emission stack, the second emission stack, or the third emission stack includes a red emission layer, Wherein the red emission layer includes a red host, a red dopant, and a charge scavenger, Wherein the charge scavenger includes an organometallic compound selected from Compound 1 and Compound 13:

10. An organic light-emitting display device, comprising: A substrate; A driving element located on the substrate; and An organic light-emitting element disposed on the substrate and connected to the driving element, wherein the organic light-emitting element includes the organic light-emitting device according to claim 1.

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