CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2020-0052884, filed on Apr. 29, 2020, in the Korean Intellectual Property Office, the content of which is incorporated herein in its entirety by reference.

BACKGROUND
1. Field

One or more embodiments relate to an organometallic compound, an organic light-emitting device including the same, and an electronic apparatus including the organic light-emitting device.

2. Description of Related Art

Organic light-emitting devices are self-emission devices, which have improved characteristics in terms of viewing angles, response times, brightness, driving voltage, and response speed, and produce full-color images.

In an example, an organic light-emitting device includes an anode, a cathode, and an organic layer between the anode and the cathode, wherein the organic layer includes an emission layer. A hole transport region may be between the anode and the emission layer, and an electron transport region may be between the emission layer and the cathode. Holes provided from the anode may move toward the emission layer through the hole transport region, and electrons provided from the cathode may move toward the emission layer through the electron transport region. The holes and the electrons recombine in the emission layer to produce excitons. These excitons transit from an excited state to a ground state to thereby generate light.

SUMMARY

One or more embodiments include a novel organometallic compound, an organic light-emitting device including the same, and an electronic apparatus including the organic light-emitting device.

Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments of the disclosure.

According to one or more embodiments, an organometallic compound has

a charge capture ability (CCA) of about 4.0 to about 10.5, wherein

the CCA is represented by Equation 1,

wherein the organometallic compound includes a transition metal and a ligand(s) in the number of n linked to the transition metal, wherein

n is an integer from 1 to 6,

the ligand(s) in the number of n includes at least one ligand linked to the transition metal through carbon, nitrogen, or a combination thereof, and

the ligand(s) in the number of n does not include a ligand linked to the transition metal through two oxygens:

Charge Capture Ability (CCA)=5×10⁻⁹×DM×PD, Equation 1

wherein, in Equation 1,

DM indicates a dipole moment of the organometallic compound evaluated by a density functional theory (DFT) calculation based on Hartree atomic units, and

PD indicates a polarizability determinant of the organometallic compound evaluated by a DFT calculation based on Hartree atomic units.

According to one or more embodiments, an organic light-emitting device includes: a first electrode; a second electrode facing the first electrode; and an organic layer including an emission layer and at least one organometallic compound, wherein the organic layer is between the first electrode and the second electrode.

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

According to one or more embodiments, an electronic apparatus includes the organic light-emitting device.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic cross-sectional view of an organic light-emitting device according to an exemplary embodiment; and

FIG. 2 shows data of Tables 2 and 3 represented in contour plots, wherein the x-axis represents charge capture ability (CCA), the y-axis represents a dopant amount (mol %) per 100 mol % of an emission layer, and the z-axis represents a relative lifespan (%) of an organic light-emitting device shown in shades, the organic light-emitting device including an emission layer including a dopant with CCA of the corresponding x-axis at an amount (mol %) of the corresponding y-axis.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain aspects. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.

It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.

It will be understood that, although the terms “first,” “second,” “third” etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, “a first element,” “component,” “region,” “layer” or “section” discussed below could be termed a second element, component, region, layer or section without departing from the teachings herein.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, “a,” “an,” “the,” and “at least one” do not denote a limitation of quantity, and are intended to cover both the singular and plural, unless the context clearly indicates otherwise. For example, “an element” has the same meaning as “at least one element,” unless the context clearly indicates otherwise.

“Or” means “and/or.” As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or “top,” may be used herein to describe one element's relationship to another element as illustrated in the Figures. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. For example, if the device in one of the figures is turned over, elements described as being on the “lower” side of other elements would then be oriented on “upper” sides of the other elements. The exemplary term “lower,” can therefore, encompasses both an orientation of “lower” and “upper,” depending on the particular orientation of the figure. Similarly, if the device in one of the figures is turned over, elements described as “below” or “beneath” other elements would then be oriented “above” the other elements. The exemplary terms “below” or “beneath” can, therefore, encompass both an orientation of above and below.

“About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” can mean within one or more standard deviations, or within ±30%, 20%, 10% or 5% of the stated value.

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

Exemplary embodiments are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present claims.

According to one or more embodiments, an organometallic compound has a charge capture ability (CCA) of about 4.0 to about 10.5.

For example, the organometallic compound may have a CCA of about 4.30 to about 10.25.

The CCA refers to charge-capturing characteristics of the organometallic compound, and may be represented by Equation 1:

Charge Capture Ability (CCA)=5×10⁻⁹×DM×PD. Equation 1

In Equation 1, DM indicates a dipole moment of the organometallic compound evaluated by a density functional theory (DFT) calculation based on Hartree atomic units, and

PD indicates a polarizability determinant of the organometallic compound evaluated by a DFT calculation based on Hartree atomic units.

In one or more embodiments, the constant “5×10⁻⁹” introduced in Equation 1 is a constant introduced to control the number of digits of the CCA.

The Hartree atomic units are also referred to as atomic units (au, or a.u.), and are a system of natural units of measurement which is widely known in the fields of atomic physics and computational chemistry calculations. The Hartree atomic units are clearly distinguished from the Rydberg atomic units and atomic mass units, and are a unit system for focusing especially on the characteristics of electrons. In this regard, in the Hartree atomic units, all four fundamental physical constants including 1) electron mass, 2) elementary charge, 3) reduced Planck constant, and 4) inverse Coulomb constant are defined as “1”. In Equation 1 calculated based on such Hartree atomic units, DM and PM do not have a measurement unit such as debye, and it would be easily recognized by those skilled in the art.

The DFT calculation may be performed by using various quantum mechanical calculation programs. For example, the quantum mechanical calculation programs include Gaussian, Games, Psi4, and the like.

In one or more embodiments, the DFT calculation may be performed by a Gaussian program, such as a Gaussian 09 program.

In one or more embodiments, when using the Gaussian program, the B3LYP/LanL2DZ function is used for a metal included in a compound to be measured for DM and PM and the B3LYP/6-31G(D,P) function is used for an organic ligand included in a compound to be measured for DM and PM, so as to optimize the molecular structure of the compound to be measured for DM and PM.

In one or more embodiments, a process of calculating DM of Equation 1 by using the Gaussian program may include: 1) a step of calculating a dipole moment in debye units represented by “Dipole moment (field-independent basis, debye): X, Y, Z, Tot” and 2) a step of applying the formula “1 debye=0.3934 a.u.” to the dipole moment in debye units and converting it into DM of Equation 1 based on the Hartree atomic units.

In one or more embodiments, a process of calculating PM of Equation 1 by using the Gaussian program may include: 1) a step of calculating polarizability represented by “Exact polarizability: α_x, α_xy, α_yy, α_xz, α_yz, α_zz” and 2) a step of calculating PD according to Equation 1A for the polarizability and converting it into PM of Equation 1 based on the Hartree atomic units:

PD
=

det
(

⁢

α
xx

α
xy

α
xz

α
xy

α
yy

α
yz

α
xz

α
yz

α
zz

⁢

)

=



⁢

α
xx

α
xy

α
xz

α
xy

α
yy

α
yz

α
xz

α
yz

α
zz



.

Equation
⁢

⁢
1
⁢
A

Although not intended to be limited by a specific theory, the organometallic compound included in an emission layer of an organic light-emitting device may have characteristics of capturing charges (holes and/or electrons) injected from a pair of electrodes.

In one or more embodiments, when an amount of captured charges of the organometallic compound included in an emission is too large, the charge transport in an emission layer is not smooth so that a recombination zone of holes and electrons may be formed too locally. As a result, triplet-triplet annihilation and/or triplet-polaron quenching may increase since the concentration of excitons in the recombination zone becomes too high, and in this regard, a lifespan of an organic light-emitting device may be reduced.

In one or more embodiments, when the amount of captured charges of the organometallic compound included in an emission layer is too small, the charge transport in an emission layer is active so that the recombination zone is formed too widely. As a result, charges that fail to be recombined may be accumulated at both interfaces of an emission layer, and in this regard, a lifespan of an organic light-emitting device may be reduced.

Thus, the inventors of the present disclosure discovered that a lifespan of an organic light-emitting device including the organometallic compound may be significantly improved by controlling the amount of captured charges of the organometallic compound, and that the control of the amount of captured charges of the organometallic compound related to a lifespan of an organic light-emitting device may be achieved by controlling a dipole moment (i.e., DM of Equation 1) and a polarizability determinant (i.e., PM of Equation 1) of the organometallic compound.

In detail, the dipole moment of the organometallic compound is regarded as a parameter related to a charge capture radius of the organometallic compound, and the polarizability determinant of the organometallic compound is regarded as a parameter related to an induced dipole moment generated by an electric field when driving an organic light-emitting device. Thus, both the dipole moment and the polarizability determinant should be considered to effectively control the charge capturing characteristics of the organometallic compound.

The organometallic compound may emit green light.

In one or more embodiments, the organometallic compound may emit light having a maximum emission wavelength from about 490 nm to about 550 nm.

For example, a maximum emission wavelength of a PL spectrum and/or an EL spectrum of the organometallic compound may be from about 490 nm to about 550 nm.

In one or more embodiments, the organometallic compound may include a transition metal and a ligand in the number of n linked to the transition metal.

For example, the transition metal may be a first-row transition metal, a second-row transition metal, or a third-row transition metal of the Periodic Table of Elements.

In one or more embodiments, the transition metal may be iridium (Ir), platinum (Pt), osmium (Os), titanium (Ti), zirconium (Zr), hafnium (Hf), europium (Eu), terbium (Tb), thulium (Tm), rhodium (Rh), or rhenium (Re).

In one or more embodiments, the organometallic compound may include one transition metal.

In one or more embodiments, n may be an integer from 1 to 6. In one or more embodiments, n may be 2 or 3.

The ligand(s) in the number of n may include at least one ligand linked to the transition metal through carbon, nitrogen, or a combination thereof, but may not include a ligand linked to the transition metal through two oxygens (e.g., a bidentate ligand linked to the transition metal through two oxygens).

In one or more embodiments, in the organometallic compound,

the transition metal may be Ir, Os, Rh, or Re,

n may be 3, and

each of the ligands in the number of n may be a bidentate ligand linked to the transition metal through carbon, nitrogen, or a combination thereof.

In one or more embodiments, the organometallic compound may be represented by Formula 1 or 2:

M₁(L₁)_n1(L₂)_n2 Formula 1

M₂(L₁)(L₁₁). Formula 2

In Formula 1, M₁may be Ir, Os, Rh, or Re.

In Formula 1, n1 and n2 may each independently be 1 or 2, and the sum of n1 and n2 may be 3.

In Formula 2, M₂may be Pt, Pd, or Ag.

In Formulae 1 and 2, L₁and L₂may each independently be a bidentate ligand linked to the transition metal through carbon, nitrogen or a combination thereof. In Formula 2, L₁₁may be any bidentate ligand.

In Formula 1, i) L₁and L₂may be identical to each other; or ii) L₁and L₂may be different from each other.

In Formula 2, i) when n1 is 2, two L₁(s) may be identical to each other; ii) when n1 is 2, two L₁(s) may be different from each other; iii) when n2 is 2, two L₂(s) may be identical to each other; or iv) when n2 is 2, two L₂(s) may be different from each other.

In Formula 2, i) L₁and L₁₁may be identical to each other; or ii) L₁and L₁₁may be different from each other.

Two or more among L₁(s) in the number of n1 and L₂(s) in the number of n2 in Formula 1 may optionally be linked together through a first linking group to form a tetradentate ligand or a hexadentate ligand, and L₁and L₁₁in Formula 2 may optionally be linked together through a first linking group to form a tetradentate ligand. The first linking group may be understood by referring to the description of T₁in Formula 3-1 below.

In one or more embodiments, the organometallic compound may be represented by Formula 1, and L₁and L₂in Formula 1 may be different from each other.

In one or more embodiments, L₁in Formulae 1 and 2 may be a ligand represented by Formula 3-1, and L₂in Formula 1 may be a ligand represented by Formula 3-2:

[Image Omitted]

In Formulae 3-1 and 3-2, * and *′ each indicate a binding site to M in Formula 1 or M₂in Formula 2.

In Formulae 3-1 and 3-2, Y₁to Y₄may each independently be N or C.

For example, in Formulae 3-1 and 3-2, Y₁and Y₃may each independently be N, and Y₂and Y₄may each independently be C.

A bond between Y₁in Formula 3-1 and each of M₁in Formula 1 and M₂in Formula 2 may be a coordinate bond, a bond between Y₂in Formula 3-1 and each of M₁in Formula 1 and M₂in Formula 2 may be a covalent bond, a bond between M₁in Formula 1 and Y₃in Formula 3-2 may be a coordinate bond, and a bond between M₁in Formula 1 and Y₄in Formula 3-2 may be a covalent bond. Thus, the organometallic compound represented by Formula 1 may be electrically neutral.

In Formulae 3-1 and 3-2, ring CY₁to ring CY₄may each independently be a C₅-C₃₀carbocyclic group or a C₂-C₃₀heterocyclic group.

For example, in Formulae 3-1 and 3-2, ring CY₁to ring CY₄may each independently be i) a first ring, ii) a second ring, iii) a condensed ring in which two or more first rings are condensed with each other, iv) a condensed ring in which two or more second rings are condensed with each other, or v) a condensed ring in which one or more first rings and one or more second rings are condensed with each other,

the first ring may be a cyclopentane group, a cyclopentadiene group, a furan group, a thiophene group, a pyrrole group, a silole group, a germole group, a borole group, a phosphole group, an oxazole group, an oxadiazole group, an oxatriazole group, a thiazole group, a thiadiazole group, a thiatriazole group, an isothiatriazole group, a pyrazole group, an imidazole group, a triazole group, a tetrazole group, an azasilole group, an azagermole group, an azaborole group, or an azaphosphole group, and

the second ring may be an adamantane group, a norbornane group, a norbornene group, a bicyclo[1.1.1]pentane group, a bicyclo[2.1.1]hexane group, a bicyclo[2.2.2]octane group, a cyclohexane group, a cyclohexene group, a benzene group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, or a triazine group.

In one or more embodiments, ring CY₁to CY₄in Formulae 3-1 and 3-2 may each independently be a cyclopentene group, a cyclohexane group, a cyclohexene group, a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a thiophene group, a furan group, an indole group, a benzoborole group, a benzophosphole group, an indene group, a benzosilole group, a benzogermole group, a benzothiophene group, a benzoselenophene group, a benzofuran group, a carbazole group, a dibenzoborole group, a dibenzophosphole group, a fluorene group, a dibenzosilole group, a dibenzogermole group, a dibenzothiophene group, a dibenzoselenophene group, a dibenzofuran group, a dibenzothiophene 5-oxide group, a 9H-fluorene-9-one group, a dibenzothiophene 5,5-dioxide group, an azaindole group, an azabenzoborole group, an azabenzophosphole group, an azaindene group, an azabenzosilole group, an azabenzogermole group, an azabenzothiophene group, an azabenzoselenophene group, an azabenzofuran group, an azacarbazole group, an azadibenzoborole group, an azadibenzophosphole group, an azafluorene group, an azadibenzosilole group, an azadibenzogermole group, an azadibenzothiophene group, an azadibenzoselenophene group, an azadibenzofuran group, an azadibenzothiophene 5-oxide group, an aza-9H-fluorene-9-one group, an azadibenzothiophene 5,5-dioxide group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isooxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group, a 5,6,7,8-tetrahydroquinoline group, a 5,6,7,8-tetrahydroquinoline group, an adamantane group, a norbornane group, or a norbornene group.

In one or more embodiments, in Formulae 3-1 and 3-2, Y₁and Y₃may each be N, ring CY₁and ring CY₃may each independently be a group represented by one of Formulae CYN-1 to CYN-52, and in Formulae 3-1 and 3-2, Y₂and Y₄may each be C, and ring CY₂and ring CY₄may each independently be a group represented by one of Formulae CYC-1 to CYC-65:

[Image Omitted]

In Formulae CYN-1 to CYN-52, X₁may be O, S, N, C, or Si (for example, 0, S, N(R₁₉), C(R₁₉)(R₂₀), or Si(R₁₉)(R₂₀)), *′ indicates a binding site to M₁in Formula 1 or M₂in Formula 2, and *″ indicates a binding site to T₁or T₃in Formulae 3-1 and 3-2, and

in Formulae CYC-1 to CYC-65, X₂may be O, S, N, C, or Si (for example, 0, S, N(R₁₉), C(R₁₉)(R₂₀), or Si(R₁₉)(R₂₀)), * indicates a binding site to M₁in Formula 1 or M₂in Formula 2, and *″ indicates a binding site to T₁or T₃in Formulae 3-1 and 3-2. It may be understood by those of ordinary skill in the art by referring Formulae 3-1 and 3-2 that at least one of N, C and Si, which are each independently a ring-forming atom in Formulae CYN-1 to CYN-52 and CYC-1 to CYC-65, may be optionally bound to a group represented by *-(A₁)_b1-R₁, a group represented by *-(A₂)_b2-R₂, a group represented by *-(A₃)_b3-R₃, and/or a group represented by *-(A₄)_b4-R₄.

In one or more embodiments,

ring CY₁in Formula 3-1 may be a pyridine group or a pyrimidine group, and/or

ring CY₂in Formula 3-1 may be a benzene group, a dibenzofuran group, a dibenzothiophene group, a carbazole group, a fluorene group, or a dibenzosilole group, and/or

ring CY₃in Formula 3-2 may be a benzimidazole group, a pyridoimidazole group, a pyridine group, or a pyrimidine group, and/or

ring CY₄in Formula 3-2 may be a dibenzofuran group, a dibenzothiophene group, a carbazole group, a fluorene group, a dibenzosilole group, an azadibenzofuran group, an azadibenzothiophene group, an azacarbazole group, an azafluorene group, or an azadibenzosilole group.

T₁and T₃in Formulae 3-1 and 3-2 may each independently be a single bond, a double bond, *—N(R₇)—*′, *—B(R₇)—*′, *—P(R₇)—*′, *—C(R₇)(R₈)—*′, *—Si(R₇)(R₈)—*′, *—Ge(R₇)(R₈)—*′, *—S—*′, *—Se—*′, *—O—*′, *—C(═O)—*′, *—S(═O)—*′, *—S(═O)₂—*′, *—C(R₇)=*′, *═C(R₇)—*′, *—C(R₇)═C(R₈)—*′, *—C(═S)—*′, or *—C≡C—*′. Here, * and *′ each indicate a binding site to a neighboring atom.

For example, T₁and T₃in Formulae 3-1 and 3-2 may each independently be a single bond.

In Formulae 3-1 and 3-2, A₁to A₄may each independently be a single bond, a C₅-C₃₀carbocyclic group unsubstituted or substituted with at least one R_10a, or a C₂-C₃₀heterocyclic group unsubstituted or substituted with at least one R_10a.

For example, A₁to A₄in Formulae 3-1 and 3-2 may each independently be:

a single bond; or

a cyclopentene group, a cyclohexane group, a cyclohexene group, a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a thiophene group, a furan group, an indole group, a benzoborole group, a benzophosphole group, an indene group, a benzosilole group, a benzogermole group, a benzothiophene group, a benzoselenophene group, a benzofuran group, a carbazole group, a dibenzoborole group, a dibenzophosphole group, fluorene group, a dibenzosilole group, a dibenzogermole group, a dibenzothiophene group, a dibenzoselenophene group, a dibenzofuran group, a dibenzothiophene 5-oxide group, a 9H-fluorene-9-one group, a dibenzothiophene 5,5-dioxide group, an azaindole group, an azabenzoborole group, an azabenzophosphole group, an azaindene group, an azabenzosilole group, an azabenzogermole group, an azabenzothiophene group, an azabenzoselenophene group, an azabenzofuran group, an azacarbazole group, an azadibenzoborole group, an azadibenzophosphole group, an azafluorene group, an azadibenzosilole group, an azadibenzogermole group, an azadibenzothiophene group, an azadibenzoselenophene group, an azadibenzofuran group, an azadibenzothiophene 5-oxide group, an aza-9H-fluorene-9-one group, an azadibenzothiophene 5,5-dioxide group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isooxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzoimidazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group, a 5,6,7,8-tetrahydroquinoline group, an adamantane group, a norbornane group, or a norbornene group, each unsubstituted or substituted with at least one R_10a

In Formulae 3-1 and 3-2, b1 to b4 may indicate the numbers of A₁to A₄, respectively, and may each independently be an integer from 1 to 10 (for example, 1, 2, or 3). When b1 is 2 or more, two or more of A₁(s) may be identical to or different from each other, when b2 is 2 or more, two or more of A₂(s) may be identical to or different from each other, when b3 is 2 or more, two or more of A₃(s) may be identical to or different from each other, and when b4 is 2 or more, two or more of A₄(s) may be identical to or different from each other.

In Formulae 3-1 and 3-2, R₁to R₄, R₇, and R₈may each independently be hydrogen, deuterium, —F, —Cl, —Br, —I, —SF₅, 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 heterocycloalkyl group, a substituted or unsubstituted C₃-C₁₀cycloalkenyl group, a substituted or unsubstituted heterocycloalkenyl 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 C₁-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), —Ge(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), —P(═O)(Q₈)(Q₉), or —P(Q₈)(Q₉). Q₁to Q₉are the same as described in the present specification.

For example, R₁to R₄, R₇, R₈, R₁₉, and R₂₀may each independently be:

hydrogen, 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, —SF₅, a C₁-C₂₀alkyl group, or a C₁-C₂₀alkoxy group; a C₁-C₂₀alkyl group or a C₁-C₂₀alkoxy group, substituted with deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, 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-C₁₀alkyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cycloctyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a bicyclo[2.2.2]octyl group, a (C₁-C₂₀alkyl)cyclopentyl group, a (C₁-C₂₀alkyl)cyclohexyl group, a (C₁-C₂₀alkyl)cycloheptyl group, a (C₁-C₂₀alkyl)cycloctyl group, a (C₁-C₂₀alkyl)adamantanyl group, a (C₁-C₂₀alkyl)norbornanyl group, a (C₁-C₂₀alkyl)norbornenyl group, a (C₁-C₂₀alkyl)cyclopentenyl group, a (C₁-C₂₀alkyl)cyclohexenyl group, a (C₁-C₂₀alkyl)cycloheptenyl group, a (C₁-C₂₀alkyl)bicyclo[1.1.1]pentyl group, a (C₁-C₂₀alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀alkyl)phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a pyridinyl group, a pyrimidinyl group, or any combination thereof;

a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cycloctyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀alkyl)phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, an azacarbazolyl group, an azadibenzofuranyl group or azadibenzothiophenyl group, each unsubstituted or substituted with deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, 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 cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cycloctyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a cyclopentenyl group, a cyclohexenyl group, a cycloheptenyl group, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a bicyclo[2.2.2]octyl group, a (C₁-C₂₀alkyl)cyclopentyl group, a (C₁-C₂₀alkyl)cyclohexyl group, a (C₁-C₂₀alkyl)cycloheptyl group, a (C₁-C₂₀alkyl)cycloctyl group, a (C₁-C₂₀alkyl)adamantanyl group, a (C₁-C₂₀alkyl)norbornanyl group, a (C₁-C₂₀alkyl)norbornenyl group, a (C₁-C₂₀alkyl)cyclopentenyl group, a (C₁-C₂₀alkyl)cyclohexenyl group, a (C₁-C₂₀alkyl)cycloheptenyl group, a (C₁-C₂₀alkyl)bicyclo[1.1.1]pentyl group, a (C₁-C₂₀alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀alkyl)bicyclo[2.2.2]octyl group, a phenyl group, a (C₁-C₂₀alkyl)phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a phenanthrenyl group, an anthracenyl group, a fluoranthenyl group, a triphenylenyl group, a pyrenyl group, a chrysenyl group, a pyrrolyl group, a thiophenyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an isothiazolyl group, an oxazolyl group, an isoxazolyl group, a pyridinyl group, a pyrazinyl group, a pyrimidinyl group, a pyridazinyl group, an isoindolyl group, an indolyl group, an indazolyl group, a purinyl group, a quinolinyl group, an isoquinolinyl group, a benzoquinolinyl group, a quinoxalinyl group, a quinazolinyl group, a cinnolinyl group, a carbazolyl group, a phenanthrolinyl group, a benzimidazolyl group, a benzofuranyl group, a benzothiophenyl group, an isobenzothiazolyl group, a benzoxazolyl group, an isobenzoxazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a triazinyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, an imidazopyridinyl group, an imidazopyrimidinyl group, an azacarbazolyl group, an azadibenzofuranyl group, an azadibenzothiophenyl group, or any combination thereof; or

—N(Q₁)(Q₂), —Si(Q₃)(Q₄)(Q₅), —Ge(Q₃)(Q₄)(Q₅), —B(Q₆)(Q₇), —P(═O)(Q₈)(Q₉), or —P(Q₈)(Q₉), and

Q₁to Q₉may each independently be:

—CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CH₃, —CH₂CD₃, —CH₂CD₂H, —CH₂CDH₂, —CHDCH₃, —CHDCD₂H, —CHDCDH₂, —CHDCD₃, —CD₂CD₃, —CD₂CD₂H, or —CD₂CDH₂; or

an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, a neopentyl group, an isopentyl group, a sec-pentyl group, a 3-pentyl group, a sec-isopentyl group, a phenyl group, a biphenyl group, or a naphthyl group, each unsubstituted or substituted with deuterium, a C₁-C₁₀alkyl group, a phenyl group, or any combination thereof.

In one or more embodiments, R₁to R₄, R₇, and R₈in Formulae 3-1 and 3-2 may each independently be hydrogen, deuterium, —F, cyano group, nitro group, —SF₅, —CH₃, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, a group represented by one of Formulae 9-1 to 9-39, a group in which at least one hydrogen in Formulae 9-1 to 9-39 is substituted with deuterium, a group represented by one of Formulae 9-201 to 9-237, a group in which at least one hydrogen in Formulae 9-201 to 9-237 is substituted with deuterium, a group represented by one of Formulae 10-1 to 10-129, a group in which at least one hydrogen in Formulae 10-1 to 10-129 is substituted with deuterium, a group represented by one of Formulae 10-201 to 10-350, a group in which at least one hydrogen in Formulae 10-201 to 10-350 is substituted with deuterium, —Si(Q₃)(Q₄)(Q₅), or —Ge(Q₃)(Q₄)(Q₅) (wherein Q₃to Q₅may be the same as described in the present specification):

[Image Omitted]

[Image Omitted]

In Formulae 9-1 to 9-39, 9-201 to 9-237, 10-1 to 10-129, and 10-201 to 10-350, * indicates a binding site to a neighboring atom, Ph is a phenyl group, TMS is a trimethylsilyl group, and TMG is a trimethylgermyl group.

The “group in which at least one hydrogen in Formulae 9-1 to 9-39 is substituted with deuterium” and “the group in which at least one hydrogen in Formulae 9-201 to 9-237 is substituted with deuterium” may be, for example, a group represented by one of Formulae 9-501 to 9-514 and 9-601 to 9-636:

[Image Omitted]

The “group in which at least one hydrogen in Formulae 10-1 to 10-129 is substituted with deuterium” and the “group in which at least one hydrogen in Formulae 10-201 to 10-350 is substituted with deuterium” may be, for example, a group represented by one of Formulae 10-501 to 10-553:

[Image Omitted]

In Formulae 3-1 and 3-2, a1 to a4 may each indicate the numbers of a group represented by *-(A₁)_b1-R₁, a group represented by *-(A₂)_b2-R₂, a group represented by *-(A₃)_b3-R₃, and a group represented by *-(A₄)_b4-R₄, respectively, and may each independently be an integer from 0 to 20 (for example, an integer from 0 to 8). When a1 is 2 or more, two or more groups represented by *-(A₁)_b1-R₁may be identical to or different from each other, when a2 is 2 or more, two or more groups represented by *-(A₂)_b2-R₂may be identical to or different from each other, when a3 is 2 or more, two or more groups represented by *-(A₃)_b3-R₃may be identical to or different from each other, and when a4 is 2 or more, two or more groups represented by *-(A₄)_b4-R₄may be identical to or different from each other.

For example, in Formula 3-2, R₄may not be hydrogen, and a4 may be an integer from 1 to 6.

In one or more embodiments, the organometallic compound may be represented by Formula 1, and Formula 1 may include a group represented by —Si(Q₃)(Q₄)(Q₅), a group represented by —Ge(Q₃)(Q₄)(Q₅), or any combination thereof.

In one or more embodiments, at least one of R₁(s) in the number of a1 in Formula 3-1 may be a group represented by —Si(Q₃)(Q₄)(Q₅) or a group represented by —Ge(Q₃)(Q₄)(Q₅).

In one or more embodiments, a group represented by

[Image Omitted]

in Formula 3-1 may be a group represented by one of Formulae CY1(1) to CY1(25):

[Image Omitted]

In Formulae CY1(1)-1 to CY1(25),

Y₁may be N,

R₁₁to R₁₈may be the same as described in connection with R₁, wherein, in Formulae CY1(2) to CY1(16), R₁₁to R₁₄may not be each hydrogen,

*′ indicates a binding site to M₁in Formula 1 or M₂in Formula 2, and

*″ indicates a binding site to T₁in Formula 3-1.

In one or more embodiments, a group represented by

[Image Omitted]

in Formula 3-1 may be a group represented by one of Formulae CY1-1 to CY1-4:

[Image Omitted]

In Formulae CY1-1 to CY1-4,

Y₁may be N,

X₁₂may be Si or Ge,

R₁₁to R₁₈may each be the same as described in connection with R₁,

Q₃to Q₅may each be the same as described in the present specification,

*′ indicates a binding site to M₁in Formula 1 or M₂in Formula 2, and

*″ indicates a binding site to T₁in Formula 3-1.

In one or more embodiments, R₁(s) in the number of a1 in Formula 3-1 (for example, R₁₁to R₁₈in Formulae CY1-1 to CY1-4) may each independently be hydrogen, deuterium, a C₁-C₂₀alkyl group, a deuterated C₁-C₂₀alkyl group, a C₃-C₁₀cycloalkyl group, or a deuterated C₃-C₁₀cycloalkyl group.

In one or more embodiments, R₁(s) in the number of a1 in Formula 3-1 (for example, R₁₁to R₁₈in Formulae CY1-1 to CY1-4) may each independently be hydrogen, deuterium, —F, —Cl, —Br, —I, a cyano group, a substituted or unsubstituted C₁-C₂₀alkyl group, or a substituted or unsubstituted C₃-C₁₀cycloalkyl group.

In one or more embodiments, Ru(s) in the number of a1 in Formula 3-1 (for example, R₁₁to R₁₈in Formulae CY1-1 to CY1-4) may each independently be:

hydrogen, deuterium, —F, or a cyano group;

a C₁-C₂₀alkyl group unsubstituted or substituted with deuterium, —F, cyano group, a C₃-C₁₀cycloalkyl group, a (C₁-C₂₀alkyl)C₃-C₁₀cycloalkyl group, or any combination thereof; or

a C₃-C₁₀cycloalkyl group unsubstituted or substituted with deuterium, —F, cyano group, a C₁-C₂₀alkyl group, or any combination thereof.

R₁(s) in the number of a1 in Formula 3-1 (for example, R₁₁to R₁₈in Formulae CY1-1 to CY1-4) may each independently be:

hydrogen, deuterium, —F, or a cyano group;

a C₁-C₂₀alkyl group unsubstituted or substituted with deuterium, —F, a cyano group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cycloctyl group, an adamantanyl group, a norbornanyl group(bicyclo[2.2.1]heptyl group), a norbornenyl group, a cyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, a bicyclo[2.2.2]octyl group, a (C₁-C₂₀alkyl)cyclopentyl group, a (C₁-C₂₀alkyl)cyclohexyl group, a (C₁-C₂₀alkyl)cycloheptyl group, a (C₁-C₂₀alkyl)cycloctyl group, a (C₁-C₂₀alkyl)adamantanyl group, a (C₁-C₂₀alkyl)norbornanyl group, a (C₁-C₂₀alkyl)norbornenyl group, a (C₁-C₂₀alkyl)bicyclo[1.1.1]pentyl group, a (C₁-C₂₀alkyl)bicyclo[2.1.1]hexyl group, a (C₁-C₂₀alkyl)bicyclo[2.2.2]octyl group, or any combination thereof; or a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cycloctyl group, an adamantanyl group, a norbornanyl group, a norbornenyl group, a bicyclo[1.1.1]pentyl group, a bicyclo[2.1.1]hexyl group, or a bicyclo[2.2.2]octyl group, each unsubstituted or substituted with deuterium, —F, a cyano group, a C₁-C₂₀alkyl group, or any combination thereof.

In one or more embodiments, R₁₁in Formula CY1-1 may not be hydrogen.

In one or more embodiments, R₁₁in Formula CY1-1 may be neither hydrogen nor a methyl group.

In one or more embodiments, R₁₁in Formula CY1-1 may be neither hydrogen, a methyl group, nor a cyano group.

In one or more embodiments, in Formula CY1-1, R₁₁may not be hydrogen, and R₁₂and R₁₃may each be hydrogen.

In one or more embodiments, R₁₁in Formula CY1-1 may be a group including 4 or more carbons.

In one or more embodiments, R₁₁in Formula CY1-1 may be:

a methyl group substituted with deuterium, —F, a cyano group, a C₁-C₂₀alkyl group, a deuterated C₁-C₂₀alkyl group, a C₃-C₁₀cycloalkyl group, a (C₁-C₂₀alkyl)C₃-C₁₀cycloalkyl group, a phenyl group, a (C₁-C₂₀alkyl)phenyl group, a naphthyl group, a pyridinyl group, a furanyl group, a thiophenyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, or any combination thereof; or

a C₂-C₂₀alkyl group, a C₃-C₁₀cycloalkyl group, a phenyl group, a naphthyl group, a pyridinyl group, a furanyl group, a thiophenyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, or a dibenzothiophenyl group, each unsubstituted or substituted with deuterium, —F, a cyano group, a C₁-C₂₀alkyl group, a deuterated C₁-C₂₀alkyl group, a C₃-C₁₀cycloalkyl group, a (C₁-C₂₀alkyl)C₃-C₁₀cycloalkyl group, a phenyl group, a (C₁-C₂₀alkyl)phenyl group, a naphthyl group, a pyridinyl group, a furanyl group, a thiophenyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, or any combination thereof.

In one or more embodiments, Q₁to Q₉(for example, Q₃to Q₅in Formula CY1-1) may each independently be a C₁-C₆₀alkyl group or a C₆-C₆₀aryl group, each unsubstituted or substituted with deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, 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-C₁₀alkyl group, or any combination thereof.

In one or more embodiments, Q₁to Q₉(for example, Q₃to Q₅in Formula CY1-1) may each independently be a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, a tert-pentyl group, an neopentyl group, an isopentyl group, a sec-pentyl group, a 3-pentyl group, a sec-isopentyl group, an n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an n-octyl group, an isooctyl group, a sec-octyl group, a tert-octyl group, an n-nonyl group, an isononyl group, a sec-nonyl group, a tert-nonyl group, an n-decyl group, an isodecyl group, a sec-decyl group, a tert-decyl group, a phenyl group, a biphenyl group, or a naphthyl group, each unsubstituted or substituted with deuterium, —F, —Cl, —Br, —I, —CD₃, —CD₂H, —CDH₂, —CF₃, —CF₂H, —CFH₂, hydroxyl group, cyano group, nitro group, amino group, amidino group, a hydrazine group, a hydrazone group, carboxylic acid or a salt thereof, sulfonic acid or a salt thereof, phosphoric acid or a salt thereof, C₁-C₁₀alkyl group, or any combination thereof.

In one or more embodiments, Q₁to Q₉(for example, Q₃to Q₅in Formula CY1-1) may each independently be —CH₃, —CH₂CH₃, —CD₃, —CD₂H, —CDH₂, —CH₂CD₃, or —CD₂CH₃.

In one or more embodiments, Q₃to Q₅in Formula CY1-1 may be identical to or different from each other.

In one or more embodiments, a group represented by

[Image Omitted]

in Formula 3-1 may be a group represented by one of Formulae CY2(1) to CY2(67):

[Image Omitted]

In Formulae CY2(1)-1 to CY2(67),

Y₂may be C,

X₂₁may be O, S, N(R₂₇), C(R₂₇)(R₂₈), Si(R₂₇)(R₂₈),

R₂₁to R₂₈may each be the same as described in connection with R₂, wherein, in Formulae CY2(2) to CY2(16), CY2(27) to CY2(32), CY2(34) to CY2(39), CY2(41) to CY2(46), CY2(48) to CY2(53), CY2(55) to CY2(60), and CY2(62) to CY2(67), R₂₁to R₂₆may not be each hydrogen,

* indicates a binding site to M₁in Formula 1 or M₂in Formula 2, and

*″ indicates a binding site to T₁in Formula 3-1.

In one or more embodiments, a group represented by

[Image Omitted]

in Formula 3-2 may be a group represented by one of Formulae CY3(1) to CY3(37):

[Image Omitted]

In Formulae CY3(1)-1 to CY3(37),

Y₃may be N,

A₃₅may be the same as described in connection with A₃,

R₃₁to R₃₅may each be the same as described in connection with R₃, wherein R₃₁to R₃₅may not be each hydrogen,

*′ indicates a binding site to M₁in Formula 1, and

*″ indicates a binding site to T₃in Formula 3-2.

In one or more embodiments, in Formulae CY3(17) to CY3(37),

A₃₅may be:

a single bond; or

a benzene group, a naphthalene group, a phenanthrene group, a dibenzofuran group, or a dibenzothiophene group, each unsubstituted or substituted with deuterium, a C₁-C₂₀alkyl group, a deuterated C₁-C₂₀alkyl group, a phenyl group, a (C₁-C₂₀alkyl)phenyl group, a naphthyl group, a (C₁-C₂₀alkyl)naphthyl group, a phenanthrenyl group, a (C₁-C₂₀alkyl)phenanthrenyl group, a dibenzofuranyl group, a dibenzothiophenyl, or any combination thereof, and

R₃₅may be:

hydrogen, deuterium, or a C₁-C₂₀alkyl group; or

a phenyl group, a naphthyl group, a phenanthrenyl group, a dibenzofuranyl group, or dibenzothiophenyl group, each unsubstituted or substituted with deuterium, a C₁-C₂₀alkyl group, a deuterated C₁-C₂₀alkyl group, a phenyl group, a (C₁-C₂₀alkyl)phenyl group, a naphthyl group, a (C₁-C₂₀alkyl)naphthyl group, a phenanthrenyl group, a (C₁-C₂₀alkyl)phenanthrenyl group, a dibenzofuranyl group, a dibenzothiophenyl, or any combination thereof.

In one or more embodiments, in Formulae CY3(17) to CY3(37), R₃₅may be a C₆-C₂₀aryl group simultaneously substituted with at least one C₁-C₂₀alkyl group and at least one C₆-C₂₀aryl group.

In one or more embodiments, a group represented by

[Image Omitted]

in Formula 3-2 may be a group represented by one of Formulae CY4(1) to CY4(38):

[Image Omitted]

In Formulae CY4(1)-1 to CY4(38),

Y₄may be C,

X₄₁may be O, S, N(R₄₇), C(R₄₇)(R₄₈), or Si(R₄₇)(R₄₈),

R₄₁to R₄₈may each be the same as described in connection with R₄, wherein R₄₁to R₄₆may not be each hydrogen,

* indicates a binding site to M₁in Formula 1, and

*″ indicates a binding site to T₃in Formula 3-2.

In one or more embodiments, R₁(s) in the number of a1 in Formula 3-1 (for example, R₁₁to R₁₈in Formulae CY1-1 to CY1-4) and R₄(s) in the number of a4 in Formula 3-2 (for example, R₄₁to R₄₆in Formulae CY4(1) to CY4(38)) may each independently be:

hydrogen, deuterium, —F, or a cyano group; or

a C₁-C₂₀alkyl group, a C₃-C₁₀cycloalkyl group, a phenyl group, a naphthyl group, a pyridinyl group, a furanyl group, a thiophenyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, or a dibenzothiophenyl group, each unsubstituted or substituted with deuterium, —F, cyano group, a C₁-C₂₀alkyl group, a deuterated C₁-C₂₀alkyl group, a C₃-C₁₀cycloalkyl group, a (C₁-C₂₀alkyl)C₃-C₁₀cycloalkyl group, a phenyl group, a (C₁-C₂₀alkyl)phenyl group, a naphthyl group, a pyridinyl group, a furanyl group, a thiophenyl group, a benzofuranyl group, a benzothiophenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, or any combination thereof.

Here, R₄₁to R₄₆in Formulae CY4(1) to CY4(38) may not be each hydrogen.

In one or more embodiments, the organometallic compound may include at least one deuterium.

In Formulae 3-1 and 3-2, 1) two or more of a plurality of R₁(s) may optionally be linked together to form a C₆-C₃₀carbocyclic group unsubstituted or substituted with at least one R_10aor a C₂-C₃₀heterocyclic group unsubstituted or substituted with at least one R_10a, 2) two or more of a plurality of R₂(s) may optionally be linked together to form a C₆-C₃₀carbocyclic group unsubstituted or substituted with at least one R_10aor a C₂-C₃₀heterocyclic group unsubstituted or substituted with at least one R_10a, 3) two or more of a plurality of R₃(s) may optionally be linked together to form a C₅-C₃₀carbocyclic group unsubstituted or substituted with at least one R_10aor a C₂-C₃₀heterocyclic group unsubstituted or substituted with at least one R_10a, 4) two or more of a plurality of R₄(s) may optionally be linked together to form a C₅-C₃₀carbocyclic group unsubstituted or substituted with at least one R_10aor a C₂-C₃₀heterocyclic group unsubstituted or substituted with at least one R_10a, and 5) two or more of R₁to R₄, R₇, and R₈may optionally be linked together to form a C₅-C₃₀carbocyclic group unsubstituted or substituted with at least one R_10aor a C₂-C₃₀heterocyclic group unsubstituted or substituted with at least one R_10a. In the present specification, R_10amay be the same as described in connection with R₁.

In the present specification, symbols * and *′ as used herein each indicate a binding site to a neighboring atom, unless otherwise stated.

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

Examples of the organometallic compound include one of compounds of [Group 1], one of compounds of [Group 2], and one of compounds of [Group 3]: