Organometallic compound and organic light-emitting device including the same

An organometallic compound represented by Formula 1: M(L1)n1(L2)n2  Formula 1 wherein in Formula 1, M, L1, L2, n1, and n2 are defined in the detailed description.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No. 10-2014-0059303, filed on May 16, 2014, in the Korean Intellectual Property Office, and all the benefits accruing therefrom under 35 U.S.C. § 119, the content of which is incorporated herein in its entirety by reference.

BACKGROUND

The present disclosure relates to organometallic compounds and organic light-emitting devices including the same.

2. Description of the Related Art

Organic light emitting devices (OLEDs) are self-emission devices that have wide viewing angles, high contrast ratios, and short response times. In addition, OLEDs exhibit excellent brightness, driving voltage, and response speed characteristics, and produce full-color images.

Various types of organic light emitting devices are known. However, there still remains a need in OLEDs having low driving voltage, high efficiency, high brightness, and long lifespan.

SUMMARY

Provided are novel organometallic compounds and organic light-emitting devices including the same.

According to an aspect, an organometallic compound is represented by Formula 1:
M(L1)n(L2)n2Formula 1

wherein in Formula 1,

L1may be selected from ligands represented by Formula 2;

L2may be selected from a monovalent organic ligand, a divalent organic ligand, a trivalent organic ligand, and a tetravalent organic ligand, and is different from L1;

when n1 is two or more, ligands L1may be identical or different, and when n2 is two or more, ligands L2may be identical to different;

wherein in Formula 2,

X1is N or C(R1);

X2is N or C(R2);

X3is N or C(R3); and

X4is N or C(R4);

provided that each of R5to R8is not simultaneously a hydrogen;

*and *′ each indicates a binding site to M in Formula 1;

According to another aspect, an organic light-emitting device includes:

a first electrode;

a second electrode; and

an organic layer disposed between the first electrode and the second electrode,

wherein the organic layer includes an emission layer, and further includes at least one organometallic compound represented by Formula 1.

The organometallic compound may be included in the emission layer, the organometallic compound included in the emission layer may act as a dopant, and the emission layer may further include a host.

DETAILED DESCRIPTION

An organometallic compound according to an embodiment is represented by Formula 1:
M(L1)n1(L2)n2Formula 1

For example, M in Formula 1 may be iridium or platinum, but is not limited thereto.

In Formula 1,

L1is selected from ligands represented by Formula 2,

L2is selected from a monovalent organic ligand, a divalent organic ligand, a trivalent organic ligand, and a tetravalent organic ligand, and

L2is different from L1.

L1and L2in Formula 2 will be described in detail later.

The organometallic compound represented by Formula 1 is “neutral.” That is, the organometallic compound represented by Formula 1 is not a salt consisting of the pair of a cation and an anion. Accordingly, a layer including the organometallic compound represented by Formula 1 may be formed by deposition. For example, a layer including the organometallic compound represented by Formula 1 may be effectively formed by deposition at a temperature of about 100 to about 500° C., at a vacuum degree of about 10−8to about 10−3torr, and at a deposition speed of about 0.01 to about 100 Angstrom per second (Å/sec). Accordingly, a device including the organometallic compound represented by Formula 1 may have improved manufacturing workability.

In Formula 2,

X1may be N or C(R1),

X2may be N or C(R2),

X3may be N or C(R3), and

X4may be N or C(R4).

For example, in Formula 2,

X3may be C(R3), and

but they are not limited thereto.

R1to R8are each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a substituted or unsubstituted C1-C60alkyl group, a substituted or unsubstituted C2-C60alkenyl group, a substituted or unsubstituted C2-C60alkynyl group, a substituted or unsubstituted C1-C60alkoxy group, a substituted or unsubstituted C3-C10cycloalkyl group, a substituted or unsubstituted C2-C10heterocycloalkyl group, a substituted or unsubstituted C3-C10cycloalkenyl group, a substituted or unsubstituted C2-C10heterocycloalkenyl group, a substituted or unsubstituted C6-C60aryl group, a substituted or unsubstituted C6-C60aryloxy group, a substituted or unsubstituted C6-C60arylthio group, a substituted or unsubstituted C2-C60heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —N(Q1)(Q2), —Si(Q3)(Q4)(Q5), and —B(Q6)(Q7), provided that each of R5to R8in Formula 2 is not simultaneously a hydrogen. In other words, at least one of R5to R8, which are substituents of a pyridine ring in Formula 2, is selected from substituents other than hydrogen. Q1to Q7may be understood by referring to a detailed description thereof to be provided later.

According to an embodiment, in Formula 2, R1to R8may be each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a substituted or unsubstituted C1-C20alkyl group, a substituted or unsubstituted C1-C20alkoxy group, a substituted or unsubstituted C6-C20aryl group, a substituted or unsubstituted C2-C20heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, and —Si(Q3)(Q4)(Q5).

In some embodiments, R1to R8in Formula 2 may be each independently selected from

wherein Q3to Q5and Q33to Q35may be each independently selected from a hydrogen, a C1-C20alkyl group, a C1-C20alkoxy group, a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, and an isoquinolinyl group, but they are not limited thereto.

In some embodiments, R1to R8in Formula 2 may be each independently selected from

wherein Q3to Q5and Q33to Q35may be each independently selected from a hydrogen, a C1-C20alkyl group, a C1-C20alkoxy group, a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, and an isoquinolinyl group, but they are not limited thereto.

For example, L1in Formula 1 may be selected from a ligand represented by Formula 2A below through a ligand represented by Formula 2D below, but is not limited thereto.

R1to R7in Formulae 2A to 2D may be understood by referring to the corresponding description provided herein, and R5to R7in Formulae 2A to 2D are not simultaneously a hydrogen.

* and *′ in Formulae 2A to 2D are binding sites to M in Formula 1.

For example, R5to R7in Formulae 2A to 2D may be each independently selected from

wherein Q3to Q5and Q33to Q35may be each independently selected from a hydrogen, a C1-C20alkyl group, a C1-C20alkoxy group, a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, and an isoquinolinyl group, but they are not limited thereto.

L2in Formula 1 may be selected from a ligand represented by Formula 3 below, a ligand represented by Formula 4 below, and a ligand represented by one of Formulae 5-1 to 5-4:

Y1to Y4in Formula 3 are each independently carbon (C) or nitrogen (N).

For example, in Formula 3, Y1may be N and Y4may be C, but they are not limited thereto.

For example, in Formula 3, Y2and Y3may be C, but they are not limited thereto.

In Formula 3, Y1and Y2may be linked to each other via a single bond or a double bond, and Y3and Y4may be linked to each other via a single bond or a double bond.

In Formula 3, CY1and CY2may be each independently a C5-C60carbocyclic group or a C2-C60heterocyclic group, and optionally, CY1and CY2may be linked to each other via a single bond or a first linking group.

For example, in Formula 3, CY1and CY2may be each independently a benzene, a naphthalene, a fluorene, a spiro-fluorene, an indene, a pyrrole, a thiophene, a furan, a imidazole, a pyrazole, a thiazole, an isothiazole, an oxazole, an isooxazole, a triazole, a pyridine, a pyrazine, a pyrimidine, a pyridazine, a quinoline, an isoquinoline, a benzoquinoline, a quinoxaline, a quinazoline, a carbazole, a benzoimidazole, a benzofuran, a benzothiophene, an isobenzothiophene, a benzooxazole, an isobenzooxazole, a triazole, a tetrazole, an oxadiazole, a triazine, a dibenzofuran, a dibenzothiophene, a benzofuropyridine, or a benzothienopyridine.

According to an embodiment, in Formula 3, CY1may be a pyridine, a triazole, an imidazole, a pyrazole, a benzofuropyridine, or a benzothienopyridine, and CY2may be a benzene or a pyridine, but they are not limited thereto.

In some embodiments, in Formula 3, CY1and CY2are linked to each other via a single bond or a first linking group, and the first linking group may be represented by Formula 6 below:
*—(Z31)c1—*  Formula 6

Q41to Q49may be each independently selected from

c1 is an integer of 1 to 10, and when c1 is 2 or more, groups Z31may be identical or different.

Q41to Q49may be understood by referring to a detailed description to be stated herein in connection with Z1.

For example, R41to R49in Formula 6 may be each independently selected from

a phenyl group, a naphthyl group, a pyridinyl group, and a pyrimidinyl group; but they are not limited thereto.

For example, in Formula 3, CY1and CY2may be linked to each other via a single bond or a first linking group, the first linking group may be represented by *—C(Q44)(Q44)45)-*′ or

(that is, b1 in Formula 6 is 1), and Q44to Q49may be each independently a hydrogen, a C1-C10alkyl group, or a C1-C10alkoxy group, but they are not limited thereto.

In Formula 4,

X11may be N or C(R11),

X12may be N or C(R12),

X13may be N or C(R13), and

X14may be N or C(R14).

For example, in Formula 4,

X13may be C(R13), and

X14may be C(R14), but they are not limited thereto.

Examples of Z1, Z2, and R11to R14may be understood by referring to detailed examples of R1presented herein.

a and b in Formula 3 may be each independently an integer of 1 to 5. For example, a and b may be each independently 1 or 2, but they are not limited thereto.

* and *′ in Formulae 3 and 4 are binding sites to M in Formula 1.

Y5and Y6in Formula 5-1 may be each independently carbon (C) or nitrogen (N).

Y5and Y6in Formula 5-1 may be linked to each other via a single bond or a double bond.

CY3in Formula 5-1 may be a C5-C60carbocyclic group or a C2-C60heterocyclic group. Examples of CY3in Formula 5-1 may be understood by referring to examples stated herein in connection with CY1and CY2.

Z3to Z9in Formulae 5-1 to 5-4 may be each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a substituted or unsubstituted C1-C60alkyl group, a substituted or unsubstituted C2-C60alkenyl group, a substituted or unsubstituted C2-C60alkynyl group, a substituted or unsubstituted C1-C60alkoxy group, a substituted or unsubstituted C3-C10cycloalkyl group, a substituted or unsubstituted C2-C10heterocycloalkyl group, a substituted or unsubstituted C3-C10cycloalkenyl group, a substituted or unsubstituted C2-C10heterocycloalkenyl group, a substituted or unsubstituted C6-C60aryl group, a substituted or unsubstituted C6-C60aryloxy group, a substituted or unsubstituted C6-C60arylthio group, a substituted or unsubstituted C2-C60heteroaryl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group. Z3to Z9may be understood by referring to the description provided herein in connection with Z1.

A1in Formulae 5-3 may be P or As.

X11aand X11bin Formula 5-4 may be each independently N, O, N(R34), P(R35)(R36), or As(R37)(R38). R34to R38may be understood by referring to the description provided herein in connection with Z1.

R33″in Formula 5-4 may be a single bond, a double bond, a substituted or unsubstituted C1-C5alkylene group, or a substituted or unsubstituted C2-C5alkenylene group.

* and *′ in Formulae 5-1 to 5-4 are binding sites to M in Formula 1.

In an embodiment, L2in Formula 1 may be selected from the ligand represented by Formula 3 and the ligand represented by Formula 4.

In some embodiments, L2in Formula 1 may be selected from a ligand represented by Formula 3-1 to a ligand represented by 3-142, but is not limited thereto:

Examples of Z1, Z2, Z1a, Z1b, Z2a, Z2b, Z2c, and Q44to Q49in Formulae 3-1 to 3-142 may be understood by referring to examples presented herein in connection with R1.

a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, and a triazinyl group;

a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, and a triazinyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C1-C20alkyl group, a C1-C20alkoxy group, a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, and —Si(Q33)(Q34)(Q35); and

In Formulae 3-1 to 3-142,

a4 and b4 may be each independently 1, 2, 3, or 4;

a3 and b3 may be each independently 1, 2, or 3;

a2 and b2 may be each independently 1 or 2; and

* and *′ are binding sites to M in Formula 1.

In some embodiments, L2in Formula 1 may be selected from a ligand represented by Formula 3-2, a ligand represented by Formula 3-132, and a ligand represented by Formula 4, and in Formulae 3-2, 3-132, and 4;

X13may be C(R13), and

a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, and a triazinyl group;

a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, and a triazinyl group, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C1-C20alkyl group, a C1-C20alkoxy group, a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, and —Si(Q33)(Q34)(Q35); and

a4 and b4 may be each independently 1, 2, 3, or 4; a3 and b3 may be each independently 1, 2, or 3; a2 and b2 may be each independently 1 or 2; and * and *′ are binding sites to M in Formula 1, but they are not limited thereto.

In some embodiments, L2in Formula 1 may be selected from a ligand represented by Formula 3-2A to a ligand represented by 3-2I and a ligand represented by Formula 4A, but is not limited thereto:

* and *′ in Formulae 3-2A to 3-2I and 4A are binding sites to M in Formula 1.

In some embodiments, the organometallic compound may be represented by Formulae 1A or 1B below, but is not limited thereto:

For example, in Formulae 1A and 1B,

Y1and Y2are linked to each other via a single bond or a double bond, and Y3and Y4are linked to each other via a single bond or a double bond;

CY1and CY2may be each independently a benzene, a naphthalene, a fluorene, a spiro-fluorene, an indene, a pyrrole, a thiophene, a furan, a imidazole, a pyrazole, a thiazole, an isothiazole, an oxazole, an isooxazole, a triazole, a pyridine, a pyrazine, a pyrimidine, a pyridazine, a quinoline, an isoquinoline, a benzoquinoline, a quinoxaline, a quinazoline, a carbazole, a benzoimidazole, a benzofuran, a benzothiophene, an isobenzothiophene, a benzooxazole, an isobenzooxazole, a triazole, a tetrazole, an oxadiazole, a triazine, a dibenzofuran, a dibenzothiophene, a benzofuropyridine, or a benzothienopyridine;

wherein Q3to Q5and Q33to Q35may be each independently selected from a hydrogen, a C1-C20alkyl group, a C1-C20alkoxy group, a phenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, a triazinyl group, a quinolinyl group, and an isoquinolinyl group, provided that each of R5to R8is not simultaneously a hydrogen;

a and b may be each independently 1, 2, or 3.

In some embodiments, in Formula 1A, Y1may be nitrogen (N), Y4may be carbon (C), CY1may be a pyridine, a triazole, an imidazole, a pyrazole, a benzofuropyridine, or a benzothienopyridine, and CY2may be a benzene or a pyridine, but they are not limited thereto.

n1 in Formula 1 indicates the number of L1, and may be 1, 2, or 3, and when n1 is 2 or more, two or more L1may be identical or different.

n2 in Formula 1 indicates the number of L2, and may be 0, 1, 2, 3, or 4, and when n2 is 2 or more, two or more L2may be identical or different.

In some embodiments, in Formula 1, n1 is 3, n2 is 0, and M is iridium; and i) L1includes only ligands represented by Formula 2A (in Formula 2A, R1to R4are a hydrogen, and R7is a phenyl group) and thus, three L1are identical, or ii) L1includes two ligands represented by Formula 2A (in Formula 2A, R1to R4are a hydrogen, and R7is a phenyl group) and one ligand represented by Formula 2B (in Formula 2B, R1to R4are a hydrogen, R6is a methyl group, and R7is a phenyl group).

In some other embodiments, in Formula 1, n1 is 1, n2 is 2, and M is iridium; and i) L2includes only two ligands represented by Formula 3-2A and thus, two L2may be identical, or ii) L2includes the ligand represented by Formula 3-2A and the ligand represented by Formula 3-2B and thus, two L2may be different.

The organometallic compound represented by Formula 1 may include any one selected from Compounds 1 to 33, but is not limited thereto:

Since n1 of the organometallic compound represented by Formula 1, which indicates the number of L1, is not zero, the organometallic compound represented by Formula 1 necessarily includes at least one ligand represented by Formula 2.

In Formula 2, a “pyridine-based ring” and a “benzimidazole-based ring” are linked to each other via an N—C bond (see Formula 2′). In Formula 2, each of R5to R8, which are substituents of the “pyridine-based ring,” cannot simultaneously be a hydrogen. That is, at least one of R5to R8, which are substituents of the “pyridine-based ring” in Formula 2, is a substituent that is not a hydrogen. Accordingly, in the organometallic compound represented by Formula 1, stability due to electrons in a lowest unoccupied molecular orbital (LUMO) level may improve, and thus, the organometallic compound represented by Formula 1 may have excellent electrochemical stability. Thus, an organic light-emitting device including the organometallic compound represented by Formula 1 has high-purity blue emission, in addition to high efficiency, high brightness, and long lifespan.

For example, the organometallic compound represented by Formula 1 enables emission of deep blue light which has a maximum emission wavelength of about 435 nanometers (nm) to about 500 nm, the x color coordinate of about 0.14 to about 0.20 (for example, in a range of about 0.14 to about 0.18) and the y color coordinate of about 0.10 to about 0.30 (for example, in a range of about 0.15 to about 0.25).

The highest occupied molecular orbital (HOMO), LUMO, singlet (S1) energy level, and triplet (T1) energy level of each of Compounds 1 to 33 were evaluated according to DFT method using Gaussian program (structural optimization was performed at B3LYP, 6-31G(d,p) levels), and the evaluation results are shown in Table 1 below.

Referring to Table 1, it is confirmed that Compounds 1 to 33 have HOMO, LUMO, S1energy levels and T1energy level that are suitable for use as a material for an organic light-emitting device. Accordingly, the organometallic compound represented by Formula 1 has electric characteristics that are suitable for use as a material for an organic light-emitting device.

Synthesis methods of the organometallic compound represented by Formula 1 may be apparent to one of ordinary skill in the art by referring to Synthesis Examples provided below.

The organometallic compound represented by Formula 1 is suitable for use in an organic layer of an organic light-emitting device, for example, for use as a dopant in an emission layer of the organic layer. Thus, another aspect provides an organic light-emitting device that includes:

a first electrode;

a second electrode; and

an organic layer that is disposed between the first electrode and the second electrode,

wherein the organic layer including an emission layer and at least one of the organometallic compound represented by Formula 1.

The organic light-emitting device may have, due to the inclusion of an organic layer including the organometallic compound represented by Formula 1, low driving voltage, high efficiency, high brightness, and long lifespan. An organic light-emitting device including the organometallic compound represented by Formula 1 enables emission of deep blue light which has a maximum emission wavelength of about 435 nm to about 500 nm, the x color coordinate of about 0.14 to about 0.20 (for example, in a range of about 0.14 to about 0.18) and the y color coordinate of about 0.10 to about 0.25 (for example, in a range of about 0.15 to about 0.25).

The organometallic compound of Formula 1 may be used between a pair of electrodes of an organic light-emitting device. For example, the organometallic compound represented by Formula 1 may be included in the emission layer. In this regard, the organometallic compound may act as a dopant, and the emission layer may further include a host (that is, an amount of the organometallic compound represented by Formula 1 may be smaller than that of the host).

The expression “(an organic layer) includes at least one organometallic compounds” used herein may include a case in which “(an organic layer) includes identical organometallic compounds of Formula 1 and a case in which (an organic layer) includes two or more different organometallic compounds of Formula 1.

For example, the organic layer may include, as the organometallic compound, only Compound 1. In this regard, Compound 1 may be situated in an emission layer of the organic light-emitting device. In some embodiments, the organic layer may include, as the organometallic compound, Compound 1 and Compound 2. In this regard, Compound 1 and Compound 2 may be situated in an identical layer (for example, Compound 1 and Compound 2 all may be situated in an emission layer).

The first electrode may be an anode, which is a hole injection electrode, and the second electrode may be a cathode, which is an electron injection electrode, or the first electrode may be a cathode, which is an electron injection electrode, or the second electrode may be an anode, which is a hole injection electrode.

For example, the first electrode may be an anode, and the second electrode may be a cathode, and the organic layer may include

i) a hole transport region that is disposed between the first electrode and the emission layer, wherein the hole transport region includes at least one of a hole injection layer, a hole transport layer, and an electron blocking layer, and

ii) an electron transport region that is disposed between the emission layer and the second electrode, wherein the electron transport region includes at least one selected from a hole blocking layer, an electron transport layer, and an electron injection layer.

The term “organic layer” used herein refers to a single layer and/or a plurality of layers disposed between the first electrode and the second electrode of an organic light-emitting device. The “organic layer” may include, in addition to an organic compound, an organometallic complex including metal.

FIG. 1is a schematic view of an organic light-emitting device10according to an embodiment. Hereinafter, the structure of an organic light-emitting device according to an embodiment and a method of manufacturing an organic light-emitting device according to an embodiment will be described in connection withFIG. 1. The organic light-emitting device10includes a first electrode11, an organic layer15, and a second electrode19, which are sequentially stacked.

A substrate may be additionally disposed under the first electrode11or above the second electrode19. For use as the substrate, any substrate that is used in general organic light-emitting devices may be used, and the substrate may be a glass substrate or transparent plastic substrate, each with excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and water repellency.

The first electrode11may be formed by depositing or sputtering a material for forming the first electrode on the substrate. The first electrode11may be an anode. The material for the first electrode11may be selected from materials with a high work function to make holes be easily injected. The first electrode11may be a reflective electrode, a semi-transmissive electrode, or a transmissive electrode. The material for the first electrode11may be indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO2), zinc oxide (ZnO), or the like. In some embodiments, magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), or magnesium-silver (Mg—Ag) may be used.

The first electrode11may have a single-layer structure or a multi-layer structure including two or more layers. For example, the first electrode11may have a three-layered structure of ITO/Ag/ITO, but the structure of the first electrode11is not limited thereto.

The organic layer15is disposed on the first electrode11.

The hole transport region may be disposed between the first electrode11and the emission layer.

The hole transport region may include at least one of a hole injection layer, a hole transport layer, an electron blocking layer, and a buffer layer.

The hole transport region may include only either a hole injection layer or a hole transport layer. The hole injection layer may have a single-layer structure or a multi-layer structure. For example, the hole transport region may have a structure of hole injection layer/hole transport layer, a structure of hole injection layer/hole transport layer/electron blocking layer, and a structure of first hole injection layer/second hole injection layer/electron blocking layer, each stacked in this stated order on the first electrode11, but the structure of the hole transport region is not limited thereto.

When the hole transport region includes a hole injection layer (HIL), the hole injection layer may be formed on the first electrode11by using various methods, such as vacuum deposition, spin coating, casting, or Langmuir-Blodgett (LB).

When a hole injection layer is formed by vacuum deposition, the deposition conditions may vary according to a material that is used to form the hole injection layer, and the structure and thermal characteristics of the hole injection layer. For example, the deposition conditions may include a deposition temperature of about 100 to about 500° C., a vacuum pressure of about 10−8to about 10−3torr, and a deposition rate of about 0.01 to about 100 Å/sec. However, the deposition conditions are not limited thereto.

When the hole injection layer is formed using spin coating, coating conditions may vary according to the material used to form the hole injection layer, and the structure and thermal properties of the hole injection layer. For example, a coating speed may be from about 2,000 revolutions per minute (rpm) to about 5,000 rpm, and a temperature at which a heat treatment is performed to remove a solvent after coating may be from about 80° C. to about 200° C. However, the coating conditions are not limited thereto.

Conditions for a hole transport layer and an electron blocking layer may be understood by referring to conditions for forming the hole injection layer.

Ar101to Ar102in Formula 201 may be each independently selected from

In Formula 201, xa and xb may be each independently an integer of 0 to 5, for example 0, 1, or 2. For example, xa may be 1 and xb may be 0, but they are not limited thereto.

a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C1-C10alkyl group (for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and so on), and a C1-C10alkoxy group (for example, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, or a pentoxy group);

a phenyl group, a naphthyl group, an anthracenyl group, a fluorenyl group, and a pyrenyl group; and

R109in Formula 201 may be selected from

a phenyl group, a naphthyl group, an anthracenyl group and a pyridinyl group; and

According to an embodiment, the compound represented by Formula 201 may be represented by Formula 201A, but is not limited thereto:

R101, R111, R112, and R109in Formula 201A may be understood by referring to the description provided herein.

For example, the compound represented by Formula 201, and the compound represented by Formula 202 may include compounds HT1 to HT20 illustrated below, but are not limited thereto.

For example, the hole transport region may include a first hole injection layer and a second hole injection layer, and the second hole injection layer may include the electron-generation material alone or together with other materials.

The hole transport region may include a buffer layer.

Also, the buffer layer may compensate for an optical resonance distance according to a wavelength of light emitted from the emission layer, and thus, efficiency of a formed organic light-emitting device may be improved.

Then, an emission layer (EML) may be formed on the hole transport region by vacuum deposition, spin coating, casting, LB deposition, or the like. When the emission layer is formed by vacuum deposition or spin coating, the deposition or coating conditions may be similar to those applied to form the hole injection layer although the deposition or coating conditions may vary according to the material that is used to form the emission layer.

The emission layer may include a host and a dopant, and the dopant may include the organometallic compound represented by Formula 1.

The host may be any known host. The host may include, for example, identical compounds or two different compounds.

For example, the host may be CBP, CDBP, TCP, or mCP, but is not limited thereto.

When the organic light-emitting device is a full color organic light-emitting device, the emission layer may be patterned into a red emission layer, a green emission layer, and a blue emission layer. According to another embodiment, due to a stacked structure including a red emission layer, a green emission layer, and/or a blue emission layer, the emission layer may emit white light.

When the emission layer includes a host and a dopant, an amount of the dopant may be in a range of about 0.01 to about 15 parts by weight based on 100 parts by weight of the host, but is not limited thereto.

Then, an electron transport region may be disposed on the emission layer.

The electron transport region may include at least one selected from a hole blocking layer, an electron transport layer, and an electron injection layer.

For example, the electron transport region may have a structure of hole blocking layer/electron transport layer/electron injection layer or a structure of electron transport layer/electron injection layer, but the structure of the electron transport region is not limited thereto. The electron transport layer may have a single-layered structure or a multi-layer structure including two or more different materials.

Conditions for forming the hole blocking layer, the electron transport layer, and the electron injection layer which constitute the electron transport region may be understood by referring to the conditions for forming the hole injection layer.

When the electron transport layer includes a hole blocking layer, the hole blocking layer may include, for example, at least one of BCP and Bphen, but may also include other materials.

A thickness of the hole blocking layer may be in a range of about 20 Å to about 1,000 Å, for example, about 30 Å to about 300 Å. When the thickness of the hole blocking layer is within these ranges, the hole blocking layer may have improved hole blocking ability without a substantial increase in driving voltage.

The electron transport layer may further include at least one selected from BCP, Bphen, Alq3, Balq, TAZ, and NTAZ.

In some embodiments, the electron transport layer may include at least one selected from ET1 and ET19, but are not limited thereto.

The electron transport region may include an electron injection layer (EIL) that allows electrons to be easily provided from a second electrode19.

The electron injection layer may include at least one selected from, LiF, NaCl, CsF, Li2O, BaO, and LiQ.

The second electrode19is disposed on the organic layer15. The second electrode19may be a cathode. A material for forming the second electrode19may be selected from metal, an alloy, an electrically conductive compound, and a combination thereof, which have a relatively low work function. For example, lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), or magnesium-silver (Mg—Ag) may be used as a material for forming the second electrode19. To manufacture a top emission type light-emitting device, a transmissive electrode formed using ITO or IZO may be used as the second electrode19.

Hereinbefore, the organic light-emitting device has been described with reference toFIG. 1, but is not limited thereto.

A C1-C60alkyl group used herein refers to a linear or branched aliphatic hydrocarbon monovalent group having 1 to 60 carbon atoms. Detailed examples thereof are a methyl group, an ethyl group, a propyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an iso-amyl group, and a hexyl group. A C1-C60alkylene group used herein refers to a divalent group having the same structure as the C1-C60alkyl group.

A C2-C60alkenyl group used herein refers to a hydrocarbon group formed by substituting at least one carbon double bond in the middle or at the terminal of the C2-C60alkyl group. Detailed examples thereof are an ethenyl group, a propenyl group, and a butenyl group. A C2-C60alkenylene group used herein refers to a divalent group having the same structure as the C2-C60alkenyl group.

A C2-C60alkynyl group used herein refers to a hydrocarbon group formed by substituting at least one carbon trip bond in the middle or at the terminal of the C2-C60alkyl group. Detailed examples thereof are an ethynyl group, and a propynyl group. A C2-C60alkynylene group used herein refers to a divalent group having the same structure as the C2-C60alkynyl group.

A C2-C10heterocycloalkyl group used herein refers to a monovalent monocyclic group having at least one hetero atom selected from N, O, P, and S as a ring-forming atom and 2 to 10 carbon atoms. Detailed examples thereof are a tetrahydrofuranyl group, and a tetrahydrothiophenyl group. A C2-C10heterocycloalkylene group used herein refers to a divalent group having the same structure as the C2-C10heterocycloalkyl group.

A C3-C10cycloalkenyl group used herein refers to a monovalent monocyclic group that has 3 to 10 carbon atoms and at least one double bond in the ring thereof and does not have aromaticity. Detailed examples thereof are a cyclopentenyl group, a cyclohexenyl group, and a cycloheptenyl group. A C3-C10cycloalkenylene group used herein refers to a divalent group having the same structure as the C3-C10cycloalkenyl group.

A C2-C10heterocycloalkenyl group used herein refers to a monovalent monocyclic group that has at least one hetero atom selected from N, O, P, and S as a ring-forming atom, 2 to 10 carbon atoms, and at least one double bond in its ring. Detailed examples of the C2-C10heterocycloalkenyl group are a 2,3-dihydrofuranyl group and a 2,3-dihydrothiophenyl group. A C2-C10heterocycloalkenylene group used herein refers to a divalent group having the same structure as the C2-C10heterocycloalkenyl group.

A monovalent non-aromatic condensed polycyclic group used herein refers to a monovalent group (for example, having 8 to 60 carbon atoms) that has two or more rings condensed to each other, only carbon atoms as ring forming atoms, wherein the molecular structure as a whole is non-aromatic in the entire molecular structure. A detailed example of the monovalent non-aromatic condensed polycyclic group is a fluorenyl group. A divalent non-aromatic condensed polycyclic group used herein refers to a divalent group having the same structure as the monovalent non-aromatic condensed polycyclic group.

A monovalent non-aromatic condensed heteropolycyclic group used herein refers to a monovalent group (for example, having 2 to 60 carbon atoms) that has two or more rings condensed to each other, has a heteroatom selected from N, O P, and S, other than carbon atoms, as ring forming atoms, wherein the molecular structure as a whole is non-aromatic in the entire molecular structure. An example of the monovalent non-aromatic condensed heteropolycyclic group is a carbazolyl group. A divalent non-aromatic condensed heteropolycyclic group used herein refers to a divalent group having the same structure as the monovalent non-aromatic condensed heteropolycyclic group.

Hereinafter, a compound and an organic light-emitting device according to embodiments are described in detail with reference to Synthesis Example and Examples. However, the organic light-emitting device is not limited thereto. The wording “B was used instead of A” used in describing Synthesis Examples means that a molar equivalent of A was identical to a molar equivalent of B.

EXAMPLES

Synthesis Example 1

Synthesis of Intermediate A-1

Intermediate A-1 was synthesized as shown in Reaction Scheme 1.

Synthesis of Intermediate A-2

Intermediate A-3 (25 g), phenyl boronic acid (10.74 g), Pd(PPh3)4(3.05 g), K2CO3(24.3 g), and THF (333 mL), and distilled water (166 mL) were all placed in a 1 L reaction container, and then refluxed under nitrogen for 12 hours. When the reaction stopped, the result was cooled to room temperature, and then, an aqueous layer was removed, and an organic layer collected was washed once with 5% brine (500 mL) and once with distilled water (500 mL). The resultant organic layer was dried with MgSO4, and then, a solvent was removed therefrom, and then, the result was refined by silica gel column chromatography using a mixed solvent including ethyl acetate (EA) and n-hexane (at a ratio of 3:97) solvent to obtain Intermediate A-2 (12.4 g).

Synthesis of Intermediate A-1

Intermediate A-2 (10 g), benzimidazole (5 g), KOt-Bu (6.7 g), CuI (0.4 g), benzotriazole (0.5 g), and dimethylsulfoxide (50 mL) were all placed in a 100 mL reaction container, and then, refluxed under nitrogen for 12 hours. When the reaction stopped, the result was cooled to room temperature, and then, ethyl acetate (1 L) and 0.1 N HCl aqueous solution (1 L) were added thereto, and then, an organic layer was isolated and washed with 5% brine (1 L). The resultant organic layer was dried with MgSO4, and then, a solvent was removed therefrom, and then, the result was refined by silica gel column chromatography using a mixed solvent including EA and n-hexane (at a ratio of 50:50) solvent to obtain Intermediate A-1 (4.98 g).

Synthesis Example 2

Synthesis of Intermediate B-1

Synthesis of Intermediate B-2

Intermediate B-2 was synthesized in the same manner as used to synthesize Intermediate A-2 in Synthesis Example 1, except that Intermediate B-3 shown in Table 2 was used instead of Intermediate A-3. The synthesis yield and MS data of Intermediate B-2 are shown in Table 2.

Synthesis of Intermediate B-1

Intermediate B-1 was synthesized in the same manner as used to synthesize Intermediate A-1 in Synthesis Example 1, except that Intermediate B-2 was used instead of Intermediate A-2. The synthesis yield and MS data of Intermediate B-1 are shown in Table 2.

Synthesis Example 3

Synthesis of Intermediate C-1

Synthesis of Intermediate C-2

Intermediate C-2 was synthesized in the same manner as used to synthesize Intermediate A-2 in Synthesis Example 1, except that Intermediate C-3 shown in Table 2 was used instead of Intermediate A-3. The synthesis yield and MS data of Intermediate C-2 are shown in Table 2.

Synthesis of Intermediate C-1

Intermediate C-1 was synthesized in the same manner as used to synthesize Intermediate A-1 in Synthesis Example 1, except that Intermediate C-2 was used instead of Intermediate A-2. The synthesis yield and MS data of Intermediate C-1 are shown in Table 2.

Synthesis Example 4

Synthesis of Intermediate D-1

Intermediate D-1 was synthesized in the same manner as used to synthesize Intermediate A-1 in Synthesis Example 1, except that in synthesizing A-1, Intermediate D-2 was used instead of Intermediate A-2. The synthesis yield and MS data of Intermediate D-1 are shown in Table 2.

Synthesis Example 5

Synthesis of Compound 1

Compound 1 was synthesized as shown in Reaction Scheme 2.

Synthesis of Intermediate E-2

IrCl3-nH2O (18.7 g), E-3 (30 g), 2-ethoxyethanol (225 mL), and distilled water (75 mL) were all placed in a 1 L reaction container, and then, refluxed under nitrogen for 12 hours. When the reaction stopped, the result was cooled to room temperature. Then, distilled water (750 mL) was added to the reaction container and a solid produced was filtered, followed by being washed with distilled water (1 L), and then vacuum dried at a temperature of 60° C. for 12 hours to prepare Intermediate E-2 (23.7 g).

Synthesis of Intermediate E-1

Intermediate E-2 (23 g), AgCF3SO3(10.2 g), and acetonitrile (500 mL) were all placed in a 1 L reaction container, and then under nitrogen, refluxed for 12 hours. When the reaction stopped, the result was cooled to room temperature, and then, celite filtration was performed thereon to concentrate the residual filtrate, which was then vacuum dried for 12 hours to obtain Intermediate E-1 (27.3 g).

Synthesis of Compound 1

Intermediate E-1 (5 g), Intermediate A-1 (4.2 g), and 2-ethoxyethanol (150 mL) were all placed in a 500 mL reaction container, and then, under nitrogen, refluxed for 12 hours. When the reaction stopped, the result was cooled to room temperature, and then, distilled water (300 mL) was added thereto, and a solid produced was filtered, and washed with distilled water (200 mL). The resultant solid was dried and then refined by silica gel chromatography using a mixed solvent including dichloromethane and methanol (at a ratio of 90 to 10) to obtain Compound 1 (2.6 g).

Synthesis Example 6

Synthesis of Compound 2

Compound 2 was synthesized in the same manner as in Synthesis Example 5, except that in synthesizing Compound 1, Intermediate B-1 shown in Table 2 was used instead of Intermediate A-1. The synthesis yield and MS data of Compound 2 are shown in Table 2.

Synthesis Example 7

Synthesis of Compound 3

Compound 3 was synthesized in the same manner as in Synthesis Example 5, except that in synthesizing Compound 1, Intermediate C-1 shown in Table 2 was used instead of Intermediate A-1. The synthesis yield and MS data of Compound 3 are shown in Table 2.

Synthesis Example 8

Synthesis of Compound 4

Compound 4 was synthesized in the same manner as in Synthesis Example 5, except that in synthesizing Compound 1, Intermediate D-1 shown in Table 2 was used instead of Intermediate A-1. The synthesis yield and MS data of Compound 4 are shown in Table 3.

Synthesis Example 9

Synthesis of Compound 5

Compound 5 was synthesized in the same manner as in Synthesis Example 5, except that Intermediate F-3 shown in Table 2 was used instead of Intermediate E-3. The synthesis yield and MS data of Compound 5 are shown in Table 2.

Synthesis Example 10

Synthesis of Compound 6

Compound 6 was synthesized in the same manner as in Synthesis Example 5, except that Intermediate G-3 shown in Table 2 was used instead of Intermediate E-3. The synthesis yield and MS data of Compound 6 are shown in Table 2.

Synthesis Example 11

Synthesis of Compound 7

Compound 7 was synthesized as shown in Reaction Scheme 3.

Ir(COD)2BF4(4.0 g), Intermediate D-1 (10.14 g), and 1,2-propanediol (150 mL) were all placed in a 500 mL reaction container, and then, under nitrogen, refluxed for 12 hours. When the reaction stopped, the result was cooled to room temperature, and then, distilled water (300 mL) was added thereto, and a solid produced was filtered, and washed with distilled water (1 L). The resultant solid was dried, and then refined by silica gel chromatography using a mixed solvent including dichloromethane and methanol (at a ratio of 90 to 10) to obtain Compound 7 (2.4 g).

Evaluation Example 1

Photoluminescence (PL) Spectrum and Color Purity Evaluation

Compound 1 was diluted at a concentration of 10 mM in toluene, and PL of Compound 1 in solution was measured by using an ISC PC1 spectrofluorometer equipped with a xenon lamp. This experiment was performed on Compounds 2 to 7, and PL spectra of Compounds 1 to 7 were evaluated and results thereof are shown in Table 3.

PMMA in CH2Cl2solution and 8 percent by weight (wt %) of Compound 1 were mixed, and the obtained mixture was coated on a quartz substrate by using a spin coater, and then heat treated in an oven at a temperature of 80° C., and cooled to room temperature to obtain a film. Color-coordination-in-film of Compound 1 was evaluated using a Hamamatsu photonics absolute PL quantum yield measurement system that is equipped with a xenon light source, a monochromator, a photonic multichannel analyzer, and an integrating sphere, and uses PLQY measurement software (Hamamatsu Photonics, Ltd., Shizuoka, Japan). This experiment was performed on Compounds 2 to 7, and results thereof are shown in Table 3.

From Table 3, it was confirmed that Compounds 1 to 7 have excellent luminescent characteristics.

Evaluation Example 2

Evaluation on HOMO, LUMO, and Triplets (T1) Energy Levels of Synthesized Compounds

HOMO, LUMO and T1 energy levels of Compounds 1 to 7 were evaluated according to the method indicated in Table 4, and results thereof are shown in Table 5.

TABLE 4HOMO energy levelEach compound was diluted at a concentration of 1 × 10−5M in CHCl3, and anevaluation methodUV absorption spectrum thereof was measured at room temperature byusing a Shimadzu UV-350 spectrometer, and a HOMO energy level thereofwas calculated by using an optical band gap (Eg) from an edge of theabsorption spectrum.LUMO energy levelA potential (V)-current (A) graph of each compound was obtained by usingevaluation methodcyclic voltammetry (CV) (electrolyte: 0.1M Bu4NClO4/solvent: CH2Cl2/electrode: 3 electrode system (working electrode: GC, reference electrode:Ag/AgCl, auxiliary electrode: Pt)), and then, from reduction onset of thegraph, a LUMO energy level of the compound was calculated.T1 energy levelA mixture (each compound was dissolved in an amount of 1 mg in 3 cc ofevaluation methodtoluene) of toluene and each compound was loaded into a quartz cell, andthen, the resultant quartz cell was loaded into liquid nitrogen (77K) and aphotoluminescence spectrum thereof was measured by using a device formeasuring photoluminescence, and the obtained spectrum was comparedwith a photoluminescence spectrum measured at room temperature, andpeaks observed only at low temperature were analyzed to calculate T1energy levels.

From Table 5, it was confirmed that Compounds 1 to 7 have electric characteristics that are suitable for use as a material for forming an organic light-emitting device.

Evaluation Example 3

Thermal Characteristics Evaluation of Synthesized Compounds

Each of Compounds 1 to 7 was subjected to thermal analysis (N2atmosphere, temperature range: room temperature to 800° C. (10° C./min)-TGA, room temperature to 400° C.-DSC, Pan Type: Pt Pan in disposable Al Pan(TGA), disposable Al pan(DSC)) using thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC), and obtained results are shown in Table 6 below. As shown in Table 6, it was confirmed that the synthesized compounds had excellent thermal stability.

A glass substrate with a 1,500 Å-thick ITO (indium tin oxide) electrode (first electrode, anode) formed thereon was washed with distilled water and sonicated with ultrasonic waves. When the washing with distilled water was completed, sonication washing was performed using a solvent, such as isopropyl alcohol, acetone, or methanol. The result was dried and then transferred to a plasma washer, and the resultant substrate was washed with oxygen plasma for 5 minutes and then, transferred to a vacuum depositing device.

Compound HT3 was vacuum deposited on the ITO electrode on the glass substrate to form a first hole injection layer having a thickness of 3,500 Å, and then, Compound HT-D1 was vacuum deposited on the first hole injection layer to form a second hole injection layer having a thickness of 300 Å, and TAPC was vacuum deposited on the second hole injection layer to form an electron blocking layer having a thickness of 100 Å, thereby completing the formation of a hole transport region.

mCP (host) and Compound 1 (dopant, 7 wt %) were co-deposited on the hole transport region to form an emission layer having a thickness of 300 Å.

Compound ET3 was vacuum deposited on the emission layer to form an electron transport layer having a thickness of 250 Å, and then, ET-D1 (Liq) was deposited on the electron transport layer to form an electron injection layer having a thickness of 5 Å, and an Al second electrode (cathode) having a thickness of 1,000 Å was formed on the electron injection layer, thereby completing manufacturing of an organic light-emitting device.

An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an emission layer, as a dopant, Compound 2 was used instead of Compound 1.

An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an emission layer, as a dopant, Compound 3 was used instead of Compound 1.

An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an emission layer, as a dopant, Compound 4 was used instead of Compound 1.

An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an emission layer, as a dopant, Compound 5 was used instead of Compound 1.

An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an emission layer, as a dopant, Compound 6 was used instead of Compound 1.

An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an emission layer, as a dopant, Compound 7 was used instead of Compound 1.

Comparative Example 1

An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an emission layer, as a dopant, Compound A was used instead of Compound 1.

Comparative Example 2

An organic light-emitting device was manufactured in the same manner as in Example 1, except that in forming an emission layer, as a dopant, Compound B was used instead of Compound 1.

Evaluation Example 4

Evaluation on Characteristics of an Organic Light-Emitting Device

The current density, brightness, and luminescence efficiency, and half-lifespan according to voltage of the organic light-emitting devices manufactured according to Examples 1 to 7, and Comparative Examples 1 and 2 were measured, the measurement method is described in detail below, and results thereof are shown in Table 7. T80lifespan indicates a period of time (hr) taken for the brightness to reach 80% with respect to 100% of initial brightness:

(1) Change in Current Density According to Voltage

Regarding the manufactured organic light-emitting device, a current flowing in a unit device was measured by using a current-voltage meter (Keithley 2400) while a voltage was raised from 0 volts (V) to 10 V, and the measured current value was divided by an area.

(2) Change in Brightness According to Voltage

Regarding the manufactured organic light-emitting device, brightness was measured by using Minolta Cs-1000A while a voltage was raised from 0 V to 10 V.

Current efficiency (candelas per ampere, cd/A) was measured at the same current density (10 milliamperes per square centimeter, mA/cm2) by using brightness, current density, and voltage measured according to (1) and (2).

From Table 7, it was confirmed that the organic light-emitting devices of Examples 1 to 7 had, compared to the organic light-emitting devices of Comparative Examples 1 and 2, similar color purity, low driving voltage, high current density, high brightness, and long lifespan. Although not limited to a particular theory, as shown in Table 7, the organic light-emitting devices of Examples 1 to 7 have substantially prolonged lifespan characteristics compared to the organic light-emitting devices of Comparative Examples 1 and 2. While not wanting to be bound by a theory, it is understood that when each of R5to R8in Formula 2 is not simultaneously a hydrogen (that is, R5to R8in Formula 2 include at least one substituent that is not a hydrogen), stability of a pyridine ring of Formula 2 associated with a LUMO level of the organometallic compound described above Formula 1 improves.

The organometallic compound according to embodiments has excellent electric characteristics and thermal stability. Accordingly, an organic light-emitting device including the organometallic compound may have a low driving voltage, high efficiency, high brightness, and a long lifespan.