ORGANOMETALLIC COMPOUND AND ORGANIC LIGHT-EMITTING DEVICE INCLUDING THE SAME

Provided are an organometallic compound and an organic light-emitting device including the organometallic compound. The organometallic compound may be represented by Formula 1. In Formula 1, L1 may be a ligand represented by Formula 2A or 2B, and L2 may be a monovalent organic ligand or a divalent organic ligand.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2017-0058095, filed on May 10, 2017, in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference.

BACKGROUND

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

2. Description of the Related Art

Organic light-emitting devices are self-emission devices that produce full-color images, and also have wide viewing angles, high contrast ratios, short response times, and excellent characteristics in terms of brightness, driving voltage, and response speed, as compared to other devices in the art.

SUMMARY

Aspects of embodiments of the present disclosure provide a novel organometallic compound and an organic light-emitting device including the same.

An aspect of an embodiment of the present disclosure provides an organometallic compound represented by Formula 1 below:

M in Formula 1 may be Pt, Pd, Ir, or Os,

in Formula 1, L1may be a ligand represented by Formula 2A or 2B, and n1 may be 1 or 2, wherein, when n1 is two, two L1(s) may be identical to or different from each other,

in Formula 1, L2may be a monovalent organic ligand or a divalent organic ligand, and n2 may be 1 or 2,

the sum of n1 and n2 in Formula 1 may be 1, 2, or 3,

*1,*2, and*3in Formula 2A and*1,*2,*3, and*4in Formula 2B each indicate a binding site to M in Formula 1,

X1may be N or C, X2may be N or C, X3may be N or C, and X4may be N or C,

Y1to Y8may each independently be N or C,

a bond between X1and Y1may be a single bond or a double bond,

a bond between X1and Y2may be a single bond or a double bond,

a bond between X2and Y3may be a single bond or a double bond,

a bond between X2and Y4may be a single bond or a double bond,

a bond between X3and Y5may be a single bond or a double bond,

a bond between X3and Y6may be a single bond or a double bond,

rings A1to A4may each independently be a C5-C30carbocyclic group or a C2-C60heterocyclic group,

a5 may be selected from 1 to 3, wherein, when a5 is two or more, two or more L5(s) may be identical to or different from each other,

R15and R16may optionally be linked to a neighboring substituent selected from R11to R14to form a substituted or unsubstituted C5-C30carbocyclic group or a substituted or unsubstituted C1-C30heterocyclic group,

b1 to b4 may each independently be 0, 1, 2, or 3, wherein, when b1 is zero, *-(T1)b1-*′ may be a single bond, when b2 is zero, *-(T2)b2-*′ may be a single bond, when b3 is zero, *-(T3)b3-*′ may be a single bond, and when b4 is 0, *-(T4)b4-*′ may be a single bond,

*and *′ each indicate a binding site to a neighboring atom,

Z1to Z4may each be represented by Formula 3,

c1 to c4 may each independently be 0, 1, 2, or 3,

the sum of c1, c2, and c3 in Formula 2A may be one or more,

the sum of c1, c2, c3, and c4 in Formula 2B may be one or more,

T5in Formula 3 may be a substituted or unsubstituted C5-C30carbocyclic group or a substituted or unsubstituted C2-C60heterocyclic group,

b5 may be an integer from 0 to 5,

Another aspect of an embodiment of the present disclosure provides an organic light-emitting device including: a first electrode; a second electrode; and an organic layer between the first electrode and the second electrode and including an emission layer, wherein the organic layer includes at least one of the organometallic compound.

BRIEF DESCRIPTION OF THE DRAWING

These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawing which is a schematic view of an organic light-emitting device according to an embodiment.

DETAILED DESCRIPTION

An organometallic compound according to an embodiment is represented by Formula 1 below:

M in Formula 1 may be platinum (Pt), palladium (Pd), iridium (Ir), or osmium (Os).

In one embodiment, M may be platinum, but embodiments of the present disclosure are not limited thereto.

In Formula 1, L1may be a ligand represented by Formula 2A or 2B, and n1 may be 1 or 2, wherein, when n1 is two, two L1(s) may be identical to or different from each other.

In one embodiment, n1 is 1, but embodiments of the present disclosure are not limited thereto.

In Formula 1, L2may be a monovalent organic ligand or a divalent organic ligand, and n2 may be 0, 1, or 2.

In one embodiment, L2may be a monovalent organic ligand, but embodiments of the present disclosure are not limited thereto.

In one or more embodiments, L2may be selected from ligands represented by Formulae 3A to 3F, but embodiments of the present disclosure are not limited thereto:

In Formulae 3A to 3F,

X11may be N or C(R31), and X12may be N or C(R32),

a11 to a21 may each independently be an integer from 0 to 3,

R31and R32may optionally be linked to form a saturated or unsaturated ring, and R33and R34may optionally be linked to form a saturated or unsaturated ring,

*″ indicates a binding site to M in Formula 1,

In one embodiment, L2may be selected from —F, —Cl, —Br, and a cyano group.

In one embodiment, n2 is 0, but embodiments of the present disclosure are not limited thereto.

The sum of n1 and n2 in Formula 1 may be 1, 2, or 3.

In one embodiment, the sum of n1 and n2 may be 1 or 2, but embodiments of the present disclosure are not limited thereto.

*1,*2, and*3in Formula 2A and*1,*2,*3, and*4in Formula 2B each indicate a binding site to M in Formula 1.

In Formulae 2A and 2B, X1may be N or C, X2may be N or C, X3may be N or C, and X4may be N or C.

Y1to Y8in Formulae 2A and 2B may each independently be N or C.

In Formulae 2A and 2B,

a bond between X1and Y1may be a single bond or a double bond,

a bond between X1and Y2may be a single bond or a double bond,

a bond between X2and Y3may be a single bond or a double bond,

a bond between X2and Y4may be a single bond or a double bond,

a bond between X3and Y5may be a single bond or a double bond, and

a bond between X3and Y6may be a single bond or a double bond.

Rings A1to A4in Formulae 2A and 2B may each independently be a C5-C30carbocyclic group or a C2-C60heterocyclic group.

In one or more embodiments, rings A1to A4may each independently be selected from a benzene group, a pyridine group, a pyrimidine group, a triazine group, a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isoxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazol group, a benzopyrazole group, a benzimidazole group, an imidazopyrazinyl group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, and a benzothiadiazol group.

In one or more embodiments, rings A1to A4may each independently be selected from a benzene group, a pyridine group, a pyrimidine group, a triazine group, a pyrazole group, an imidazole group, a triazole group, a benzopyrazole group, a benzimidazole group, and an imidazopyrazinyl group, but embodiments of the present disclosure are not limited thereto.

a5 may be selected from 1 to 3, wherein, when a5 is two or more, two or more L5(s) may be identical to or different from each other, and

R15and R16may optionally be linked to a neighboring substituent selected from R11to R14to form a substituted or unsubstituted C5-C30carbocyclic group or a substituted or unsubstituted C1-C30heterocyclic group.

In one embodiment, when at least one of T1to T3is *—N[(L5)a5-(R15)]—*′, R15may be a substituted or unsubstituted C1-C60aryl group, or may optionally be linked to a neighboring substituent selected from R11to R14to form a substituted or unsubstituted C1-C60heterocyclic group.

In one or more embodiments, R15may be a substituted or unsubstituted phenyl group, or may optionally be linked to one of L1to L4to form a substituted or unsubstituted carbazole ring or a substituted or unsubstituted azacarbazole ring, but embodiments of the present disclosure are not limited thereto.

b1 to b4 in Formulae 2A and 2B may each independently be 0, 1, 2, or 3. When b1 is zero, *-(T1)b1-*′ may be a single bond, when b2 is zero, *-(T2)b2-*′ may be a single bond, when b3 is zero, *-(T3)b3-*′ may be a single bond, when b4 is zero, *-(T4)b4-*′ may be a single bond, and * and *′ each indicate a binding site to a neighboring atom.

In Formulae 2A and 2B, Z1to Z4may each be represented by Formula 3, and c1 to c4 may each independently be 0, 1, 2, or 3.

In Formulae 2A and 2B, the sum of c1, c2, and c3 in Formula 2A may be one or more, and the sum of c1, c2, c3, and c4 in Formula 2B may be one or more.

T5in Formula 3 may be a substituted or unsubstituted C5-C30carbocyclic group or a substituted or unsubstituted C2-C60heterocyclic group.

In one embodiment, rings A1to A4may each independently be selected from:

b5 in Formula 3 may be an integer from 0 to 5.

In one embodiment, b5 may be 0, 1, or 2.

In one or more embodiments, b5 may be 0.

In one or more embodiments, R3and R11to R16may each independently be selected from:

In one or more embodiments, R3and R11to R16may each independently be selected from:

In one embodiment, (i) c1 may be 1, and a moiety represented by

in Formula 2A or 2B may be represented by Formula 4A-1 or 4A-2:

In one or more embodiments, c2 may be 1, and a moiety represented by

in Formula 2A or 2B may be represented by Formula 4B-1 or 4B-2:

*1and*2each indicate a binding site to M in Formula 1.

In one embodiment, c1 may be 1, and a moiety represented by

in Formula 2A or 2B may be represented by Formula 4A-1-1:

In one or more embodiments, (ii) c2 may be 1, and a moiety represented by

in Formula 2A or 2B may be represented by Formula 4B-1-1:

In Formulae 4A-1-1 and 4B-1-1,

*1and*2each indicate a binding site to M in Formula 1.

In one embodiment, Y12and Y22in Formulae 4A-1-1 and 4B-1-1 may each be C, but embodiments of the present disclosure are not limited thereto.

In one embodiment, the organometallic compound may be selected from Compounds 1 to 42, but embodiments of the present disclosure are not limited thereto:

In general, an intermolecular aggregation easily occurs in a metal complex of a solid, for example, a d8planar metal complex such as Pt(II), due to a strong intermolecular interaction such as a ligand-ligand, metal-metal, and/or ligand-metal interaction. Due to such a phenomenon, when the degree of doping exceeds about 0.1%, which is the degree often used in the art, it is highly likely that an aggregation of complex units will be caused in an emission layer. Such aggregation causes formation what is referred to as an excimer (also referred to as exciplex) at the time of optical and/or electrical excitation. Since the excimer has a wide emission band without a regular system (e.g., the excimer does not emit light having a narrow band of wavelengths in an ordered system), it is difficult to implement pure basic colors (RGB) when the excimer is present.

In embodiments of the present disclosure, the ligand of the organometallic compound represented by Formula 1 is always substituted with the substituent represented by Formula 3, and thus is oriented in a way that an isoxazole or pyrazole substituent is perpendicular (e.g., substantially perpendicular) to the substituent represented by Formula 3. Therefore, as compared with the structure having no such substituent, steric hindrance occurs (or is increased) and the formation of an excimer is hindered by intermolecular stacking. Thus, it is possible to implement a light-emitting device having high efficiency and a long lifespan in a color region of deep blue light. For example, when the ligand and the substituent represented by Formula 3 are linked via a C—C bond, the effect of a distortion structure is increased and the effect of excimer formation suppression is increased (or maximized).

The organometallic compound according to embodiments of the present disclosure may emit blue light. For example, the organometallic compound may emit blue light having an upper (or a maximum) emission wavelength of 440 nm to 495 nm, for example, 450 nm to 465 nm (in the case of bottom emission, CIEx,ycolor coordinates (0.14, 0.06) to (0.14, 0.08)), but embodiments of the present disclosure are not limited thereto. Accordingly, the organometallic compound represented by Formula 1 may be suitably used to manufacture an organic light-emitting device that emits deep blue light.

A synthesis method for the organometallic compound represented by Formula 1 will be readily apparent to those of ordinary skill in the art by referring to the following examples.

At least one of 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 may be included in an emission layer. The organometallic compound may act as a dopant in the emission layer.

Accordingly, provided is an organic light-emitting device including: a first electrode; a second electrode facing the first electrode; and an organic layer between the first electrode and the second electrode, the organic layer including an emission layer, wherein the organic layer includes at least one organometallic compound represented by Formula 1.

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

For example, the organic layer may include, as the organometallic compound, only Compound 1. In this regard, Compound 1 may exist in an emission layer of the organic light-emitting device. In one or more embodiments, the organic layer may include, as the organometallic compound, Compound 1 and Compound 2. In this regard, Compound 1 and Compound 2 may exist in an identical layer (for example, Compound 1 and Compound 2 may all exist in an emission layer), or different layers (for example, Compound 1 may exist in an emission layer and Compound 2 may exist in an electron transport region).

According to one embodiment,

the first electrode of the organic light-emitting device may be an anode,

the second electrode of the organic light-emitting device may be a cathode,

the electron transport region may include a hole blocking layer, an electron transport layer, an electron injection layer, or any combination thereof.

The term “organic layer” as used herein refers to a single layer and/or a plurality of layers disposed between the first electrode and the second electrode of the organic light-emitting device. A material included in the “organic layer” is not limited to an organic material.

Description of the Accompanying Drawing

The accompanying drawing is a schematic view of an organic light-emitting device10according to an embodiment. The organic light-emitting device10includes a first electrode110, an organic layer150, and a second electrode190.

Hereinafter, the structure of the organic light-emitting device10according to an embodiment and a method of manufacturing the organic light-emitting device10will be described in connection with the accompanying drawing.

In the accompanying drawing, a substrate may be additionally disposed under the first electrode110or above the second electrode190. The substrate may be a glass substrate or a plastic substrate, each having excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and water resistance.

The first electrode110may be formed by depositing or sputtering a material for forming the first electrode110on the substrate. When the first electrode110is an anode, the material for a first electrode may be selected from materials with a high work function to facilitate hole injection.

The organic layer150is disposed on the first electrode110. The organic layer150may include an emission layer.

[Hole Transport Region in Organic Layer150]

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

For example, the hole transport region may have a single-layered structure including a single layer including a plurality of different materials, or a multi-layered structure having a hole injection layer/hole transport layer structure, a hole injection layer/hole transport layer/emission auxiliary layer structure, a hole injection layer/emission auxiliary layer structure, a hole transport layer/emission auxiliary layer structure, or a hole injection layer/hole transport layer/electron blocking layer structure, wherein for each structure, constituting layers are sequentially stacked from the first electrode110in this stated order, but the structure of the hole transport region is not limited thereto.

In Formulae 201 and 202,

xa5 may be an integer from 1 to 10, and

For example, in Formula 202, R201and R202may optionally be linked via a single bond, a dimethyl-methylene group, or a diphenyl-methylene group, and R203and R204may optionally be linked via a single bond, a dimethyl-methylene group, or a diphenyl-methylene group.

In one embodiment, in Formulae 201 and 202,

L201to L205may each independently be selected from:

In one or more embodiments, xa5 may be 1, 2, 3, or 4.

In one or more embodiments, R201to R204and Q201may each independently be selected from:

Q31to Q33are the same as described above.

In one or more embodiments, at least one of R201to R203in Formula 201 may each independently be selected from:

In one or more embodiments, in Formula 202, i) R201and R202may be linked via a single bond, and/or ii) R203and R204may be linked via a single bond.

In one or more embodiments, at least one of R201to R204in Formula 202 may be selected from:

a carbazolyl group; and

In one embodiment, the compound represented by Formula 201 may be represented by Formula 201A(1) below, but embodiments of the present disclosure are not limited thereto:

In one embodiment, the compound represented by Formula 201 may be represented by Formula 201A-1 below, but embodiments of the present disclosure are not limited thereto:

In one embodiment, the compound represented by Formula 202 may be represented by Formula 202A:

In one embodiment, the compound represented by Formula 202 may be represented by Formula 202A-1:

R211and R212may be understood by referring to the description provided herein in connection with R203,

The hole transport region may include at least one compound selected from Compounds HT1 to HT39, but embodiments of the present disclosure are not limited thereto:

The emission auxiliary layer may increase light-emission efficiency by compensating for an optical resonance distance according to the wavelength of light emitted by an emission layer, and the electron blocking layer may block the flow of electrons from an electron transport region. The emission auxiliary layer and the electron blocking layer may include the materials as described above.

In one embodiment, the p-dopant may have a lowest unoccupied molecular orbital of about −3.5 eV or less.

The p-dopant may include at least one selected from a quinone derivative, a metal oxide, and a cyano group-containing compound, but embodiments of the present disclosure are not limited thereto.

For example, the p-dopant may include at least one selected from:

a metal oxide, such as tungsten oxide or molybdenum oxide;

a compound represented by Formula 221 below:

In Formula 221,

[Emission Layer in Organic Layer150]

The emission layer may include a host and a dopant. The dopant may include at least one selected from a phosphorescent dopant and a fluorescent dopant.

An amount of the dopant in the emission layer may be, for example, in a range of about 0.01 parts by weight to about 15 parts by weight based on 100 parts by weight of the host, but embodiments of the present disclosure are not limited thereto.

In one or more embodiments, the host may include a compound represented by Formula 301 below.

In Formula 301,

xb1 may be an integer from 0 to 5,

xb21 may be an integer from 1 to 5, and

In one embodiment, Ar301in Formula 301 may be selected from:

When xb11 in Formula 301 is two or more, two or more of Ar301(s) may be linked via a single bond.

In one or more embodiments, the compound represented by Formula 301 may be represented by Formula 301-1 or 301-2:

In Formulae 301-1 and 301-2,

xb22 and xb23 may each independently be 0, 1, or 2,

L302to L304may each independently be the same as described in connection with L301,

xb2 to xb4 may each independently be the same as described in connection with xb1, and

R302to R304may each independently be the same as described in connection with R301.

For example, in Formulae 301, 301-1, and 301-2, L301to L304may each independently be selected from:

Q31to Q33are the same as described above.

In one embodiment, in Formulae 301, 301-1, and 301-2, R301to R304may each independently be selected from:

Q31to Q33are the same as described above.

In one or more embodiments, the host may include an alkaline earth metal complex. For example, the host may be selected from a Be complex (for example, Compound H55), a Mg complex, and a Zn complex.

In one embodiment, the host may include at least one selected from a silicon-containing compound (for example, BCPDS used in the following examples or the like) and a phosphine oxide-containing compound (for example, POPCPA used in the following examples or the like).

However, embodiments of the present disclosure are not limited thereto. In one embodiment, the host may include only one compound, or two or more different compounds (for example, a host used in the following examples includes BCPDS and POPCPA).

[Phosphorescent Dopant Included in Emission Layer in Organic Layer150]

The phosphorescent dopant may include an organometallic compound represented by Formula 1 below:

[Electron Transport Region in Organic Layer150]

The electron transport region may include at least one selected from a buffer layer, a hole blocking layer, an electron control layer, an electron transport layer, and an electron injection layer, but embodiments of the present disclosure are not limited thereto.

For example, the electron transport region may have an electron transport layer/electron injection layer structure, a hole blocking layer/electron transport layer/electron injection layer structure, an electron control layer/electron transport layer/electron injection layer structure, or a buffer layer/electron transport layer/electron injection layer structure, wherein for each structure, constituting layers are sequentially stacked from an emission layer. However, embodiments of the structure of the electron transport region are not limited thereto.

The electron transport region (for example, a buffer layer, a hole blocking layer, an electron control layer, or an electron transport layer in the electron transport region) may include a metal-free compound containing at least one π electron-depleted nitrogen-containing ring.

The “π electron-depleted nitrogen-containing ring” indicates a C1-C60heterocyclic group having at least one *—N=*′ moiety as a ring-forming moiety.

Examples of the π electron-depleted nitrogen-containing ring include an imidazole, a pyrazole, a thiazole, an isothiazole, an oxazole, an isoxazole, a pyridine, a pyrazine, a pyrimidine, a pyridazine, an indazole, a purine, a quinoline, an isoquinoline, a benzoquinoline, a phthalazine, a naphthyridine, a quinoxaline, a quinazoline, a cinnoline, a phenanthridine, an acridine, a phenanthroline, a phenazine, a benzimidazole, an isobenzothiazole, a benzoxazole, an isobenzoxazole, a triazole, a tetrazole, an oxadiazole, a triazine, thiadiazole, an imidazopyridine, an imidazopyrimidine, and an azacarbazole, but are not limited thereto.

For example, the electron transport region may include a compound represented by Formula 601:

In Formula 601,

xe1 may be an integer from 0 to 5,

xe21 may be an integer from 1 to 5.

In one embodiment, at least one of Ar601(s) in the number of xe11 and R601(s) in the number of xe21 may include the π electron-depleted nitrogen-containing ring.

In one embodiment, in Formula 601, ring Ar601may be selected from:

When xe11 in Formula 601 is two or more, two or more Ar601(s) may be linked via a single bond.

In one or more embodiments, Ar601in Formula 601 may be an anthracene group.

In one or more embodiments, a compound represented by Formula 601 may be represented by Formula 601-1:

In Formula 601-1,

X614may be N or C(R614), X615may be N or C(R615), and X616may be N or C(R616), wherein at least one selected from X614to X616may be N,

L611to L613may each independently be the same as described in connection with L601,

xe611 to xe613 may each independently be the same as described in connection with xe1,

R611to R613may each independently be the same as described in connection with R601, and

In one embodiment, in Formulae 601 and 601-1, L601and L611to L613may each independently be selected from:

In one or more embodiments, in Formulae 601 and 601-1, R601and R611to R613may each independently be selected from:

—S(═O)2(Q601), and —P(═O)(Q601)(Q602), and

Q601and Q602are the same as described above.

The electron transport region may include at least one compound selected from Compounds ET1 to ET36, but embodiments of the present disclosure are not limited thereto:

In one embodiment, the electron transport region may include a phosphine oxide-containing compound (for example, TSPO1 used in the following examples or the like), but embodiments of the present disclosure are not limited thereto. In one embodiment, the phosphine oxide-containing compound may be used in a hole blocking layer in the electron transport region, but embodiments of the present disclosure are not limited thereto.

A thickness of the buffer layer, the hole blocking layer, and/or the electron control 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 thicknesses of the buffer layer, the hole blocking layer, and/or the electron control layer are within these ranges, the electron blocking layer may have excellent electron blocking characteristics or electron control characteristics without a substantial increase in driving voltage.

The metal-containing material may include at least one selected from alkali metal complex and alkaline earth-metal complex. The alkali metal complex may include a metal ion selected from a Li ion, a Na ion, a K ion, a Rb ion, and a Cs ion, and the alkaline earth-metal complex may include a metal ion selected from a Be ion, a Mg ion, a Ca ion, a Sr ion, and a Ba ion. A ligand coordinated with the metal ion of the alkali metal complex or the alkaline earth-metal complex may be selected from a hydroxy quinoline, a hydroxy isoquinoline, a hydroxy benzoquinoline, a hydroxy acridine, a hydroxy phenanthridine, a hydroxy phenyloxazole, a hydroxy phenylthiazole, a hydroxy diphenyloxadiazole, a hydroxy diphenylthiadiazole, a hydroxy phenylpyridine, a hydroxy phenylbenzimidazole, a hydroxy phenylbenzothiazole, a bipyridine, a phenanthroline, and a cyclopentadiene, but embodiments of the present disclosure are not limited thereto.

The electron transport region may include an electron injection layer that facilitates injection of electrons from the second electrode190. The electron injection layer may directly contact the second electrode190.

The electron injection layer may include an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal compound, an alkaline earth-metal compound, a rare earth metal compound, an alkali metal complex, an alkaline earth-metal complex, a rare earth metal complex, or any combinations thereof.

The alkali metal may be selected from Li, Na, K, Rb, and Cs. In one embodiment, the alkali metal may be Li, a Na, or Cs. In one or more embodiments, the alkali metal may be Li or Cs, but embodiments of the present disclosure are not limited thereto.

The rare earth metal may be selected from Sc, Y, Ce, Tb, Yb, and Gd.

The alkali metal compound, the alkaline earth-metal compound, and the rare earth metal compound may be selected from oxides and halides (for example, fluorides, chlorides, bromides, or iodides) of the alkali metal, the alkaline earth-metal, and the rare earth metal.

The alkali metal compound may be selected from alkali metal oxides, such as Li2O, Cs2O, or K2O, and alkali metal halides, such as LiF, NaF, CsF, KF, LiI, NaI, CsI, or KI. In one embodiment, the alkali metal compound may be selected from LiF, Li2O, NaF, LiI, NaI, CsI, and KI, but embodiments of the present disclosure are not limited thereto.

The alkaline earth-metal compound may be selected from alkaline earth-metal oxides, such as BaO, SrO, CaO, BaxSr1-xO (0<x<1), or BaxCa1-xO (0<x<1). In one embodiment, the alkaline earth-metal compound may be selected from BaO, SrO, and CaO, but embodiments of the present disclosure are not limited thereto.

The rare earth metal compound may be selected from YbF3, ScF3, ScO3, Y2O3, Ce2O3, GdF3, and TbF3. In one embodiment, the rare earth metal compound may be selected from YbF3, ScF3, TbF3, Ybl3, Scl3, and Tbl3, but embodiments of the present disclosure are not limited thereto.

The alkali metal complex, the alkaline earth-metal complex, and the rare earth metal complex may include an ion of alkali metal, alkaline earth-metal, and rare earth metal as described above, and a ligand coordinated with a metal ion of the alkali metal complex, the alkaline earth-metal complex, or the rare earth metal complex may be selected from hydroxy quinoline, hydroxy isoquinoline, hydroxy benzoquinoline, hydroxy acridine, hydroxy phenanthridine, hydroxy phenyloxazole, hydroxy phenylthiazole, hydroxy diphenyloxadiazole, hydroxy diphenylthiadiazole, hydroxy phenylpyridine, hydroxy phenylbenzimidazole, hydroxy phenylbenzothiazole, bipyridine, phenanthroline, and cyclopentadiene, but embodiments of the present disclosure are not limited thereto.

The electron injection layer may include (or consist of) an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal compound, an alkaline earth-metal compound, a rare earth metal compound, an alkali metal complex, an alkaline earth-metal complex, a rare earth metal complex, or any combinations thereof, as described above. In one or more embodiments, the electron injection layer may further include an organic material. When the electron injection layer further includes an organic material, an alkali metal, an alkaline earth metal, a rare earth metal, an alkali metal compound, an alkaline earth-metal compound, a rare earth metal compound, an alkali metal complex, an alkaline earth-metal complex, a rare earth metal complex, or any combinations thereof may be homogeneously or non-homogeneously dispersed in a matrix including the organic material.

The second electrode190may be disposed on the organic layer150having such a structure. The second electrode190may be a cathode which is an electron injection electrode, and in this regard, a material for forming the second electrode190may be selected from metal, an alloy, an electrically conductive compound, and a combination thereof, which have a relatively low work function.

The second electrode190may include at least one selected from lithium (Li), silver (Ag), magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), magnesium-silver (Mg—Ag), ITO, and IZO, but embodiments of the present disclosure are not limited thereto. The second electrode190may be a transmissive electrode, a semi-transmissive electrode, or a reflective electrode.

Layers constituting the hole transport region, an emission layer, and layers constituting the electron transport region may be formed in a certain region by using one or more suitable methods selected from vacuum deposition, spin coating, casting, Langmuir-Blodgett (LB) deposition, ink-jet printing, laser-printing, and laser-induced thermal imaging.

The term “C3-C10cycloalkyl group” as used herein refers to a monovalent saturated hydrocarbon monocyclic group having 3 to 10 carbon atoms, and examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group. The term “C3-C10cycloalkylene group” as used herein refers to a divalent group having substantially the same structure as the C3-C10cycloalkyl group, except that the C3-C10cycloalkylene group is divalent.

The term “C6-C60aryloxy group” as used herein refers to —OA102(wherein A102is the C6-C60aryl group), and a C6-C60arylthio group used herein indicates —SA103(wherein A103is the C6-C60aryl group).

The term “monovalent non-aromatic condensed polycyclic group” as used herein refers to a monovalent group (for example, having 8 to 60 carbon atoms) having two or more rings condensed with each other (e.g., combined together), only carbon atoms as ring-forming atoms, and no aromaticity in its entire molecular structure. A detailed example of the monovalent non-aromatic condensed polycyclic group includes a fluorenyl group. The term “divalent non-aromatic condensed polycyclic group,” used herein, refers to a divalent group having substantially the same structure as the monovalent non-aromatic condensed polycyclic group, except that the divalent non-aromatic condensed polycyclic group is divalent.

The term “monovalent non-aromatic condensed heteropolycyclic group” as used herein refers to a monovalent group (for example, having 1 to 60 carbon atoms) having two or more rings condensed to each other, at least one heteroatom selected from N, O, Si, P, and S, other than carbon atoms, as a ring-forming atom, and no aromaticity in its entire molecular structure. An example of the monovalent non-aromatic condensed heteropolycyclic group includes a carbazolyl group. The term “divalent non-aromatic condensed heteropolycyclic group” as used herein refers to a divalent group having substantially the same structure as the monovalent non-aromatic condensed heteropolycyclic group, except that the divalent non-aromatic condensed heteropolycyclic group is divalent.

The term “C4-C60carbocyclic group” as used herein refers to a monocyclic or polycyclic group having 4 to 60 carbon atoms in which a ring-forming atom is a carbon atom only. The C4-C60carbocyclic group may be an aromatic carbocyclic group or a non-aromatic carbocyclic group. The C4-C60carbocyclic group may be a ring, such as benzene, a monovalent group, such as a phenyl group, or a divalent group, such as a phenylene group. In one or more embodiments, depending on the number of substituents connected to the C4-C60carbocyclic group, the C4-C60carbocyclic group may be a trivalent group or a quadrivalent group.

The term “C2-C60heterocyclic group” as used herein refers to a group having the same structure as the C4-C60carbocyclic group, except that as a ring-forming atom, at least one heteroatom selected from N, O, Si, P, and S is used in addition to carbon (the number of carbon atoms may be in a range of 2 to 60).

The term “Ph” as used herein represents a phenyl group, the term “Me” as used herein represents a methyl group, the term “Et” as used herein represents an ethyl group, the term “ter-Bu” or “But,” as used herein, represents a tert-butyl group, and the term “OMe” as used herein represents a methoxy group.

The term “biphenyl group” used herein refers to “a phenyl group” substituted with a phenyl group. The “biphenyl group” may be “a substituted phenyl group” having “a C6-C60aryl group” as a substituent.

The term “terphenyl group” used herein refers to a “phenyl group substituted with a biphenyl group. The “terphenyl group” may be “a substituted phenyl group” including “a substituted C6-C60aryl group” having “a C6-C60aryl group” as a substituent.

*and *′ used herein, unless defined otherwise, each refer to a binding site to a neighboring atom in a corresponding formula.

Hereinafter, a compound according to embodiments and an organic light-emitting device according to embodiments will be described in more detail with reference to Synthesis Examples and Examples. The expression “B was used instead of A” used in describing Synthesis Examples means that an identical number of molar equivalents of A was used in place of molar equivalents of B.

EXAMPLES

Synthesis Example 1: Synthesis of Compound 2

a) Synthesis of Intermediate A

5.26 g (16.7 mmol) of 1,3,5-tribromobenzene, 2.16 g (17.6 mmol) of 2-pyridineboronic acid, 0.68 g (0.59 mmol) of Pd(PPh3)4, and 4.85 g (35.1 mmol) of K2CO3were dissolved in 60 mL of tetrahydrofuran (THF) and 30 mL of distilled water and then stirred at a temperature of 80° C. for 12 hours. The reaction solution was cooled to room temperature, and an organic layer was extracted therefrom three times by using 50 mL of water and 50 mL of ethyl acetate. The obtained organic layer was dried by using magnesium sulfate, and a solvent was evaporated therefrom. Then, the residue obtained therefrom was separated and purified by silica gel column chromatography to obtain 3.50 g of Intermediate A.

b) Synthesis of Intermediate B

3.50 g (11.3 mmol) of Intermediate A, 2.44 g (11.3 mmol) of 3,5-dimethyl-1-phenyl-1H-pyrazole-4-yl)boronic acid, 0.46 g (0.40 mmol) of Pd(PPh3)4, and 3.28 g (23.8 mmol) of K2CO3were dissolved in 50 mL of THF and 25 mL of distilled water and then stirred at a temperature of 80° C. for 12 hours. The reaction solution was cooled to room temperature, and an organic layer was extracted therefrom three times by using 50 mL of water and 50 mL of ethyl acetate. The obtained organic layer was dried by using magnesium sulfate, and a solvent was evaporated therefrom. Then, the residue obtained therefrom was separated and purified by silica gel column chromatography to obtain 3.38 g of Intermediate B.

c) Synthesis of Compound 2

1.00 g (2.48 mmol) of Intermediate B and 1.03 g (2.48 mmol) of K2PtCl4were suspended in 120 mL of acetic acid and then stirred at a temperature of 110° C. for 3 days. The reaction solution was cooled to room temperature, and a precipitate was filtered therefrom, sequentially washed by using methanol, distilled water, ethanol, and diethylether, and then dried. A solid obtained therefrom was separated and purified by column chromatography to obtain 0.80 g of Compound 2.

Synthesis Example 2: Synthesis of Compound 3

0.65 g of Compound 3 was synthesized in substantially the same manner as in Synthesis Example 1, except that 2,2′-(5-(1,3,5-triphenyl-1H-pyrazol-4-yl)-1,3-phenylene)dipyridine was used instead of Intermediate B.

Synthesis Example 3: Synthesis of Compound 28

a) Synthesis of Intermediate A

2.40 g (12.05 mmol) of 2-methoxycarbazole, 4.28 g (18.05 mmol) of 3,5-dibromopyridine, 1.53 g (24.10 mmol) of Cu powder, 6.65 g (48.20 mmol) of potassium carbonate, and 0.315 g (1.200 mmol) of 18-Crown-6 were suspended in 50 mL of dimethylformamide purified by fractional distillation, and then stirred at a temperature of 150° C. for 10 hours. An organic layer was extracted from the reaction mixture by using ethyl acetate and distilled water. The extracted organic layer was dried by using magnesium sulfate and then filtered. Then, the residue obtained therefrom was purified by column chromatography (1/3=dichloromethane/normal hexane) to obtain 1.6 g of Intermediate A.

b) Synthesis of Intermediate B

1.6 g (4.50 mmol) of Intermediate A, 1.46 g (6.75 mmol) of (3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)boronic acid, 1.24 g (9.00 mmol) of potassium carbonate, and 0.30 g (0.27 mmol) of Pd(PPh3)4were suspended in 150 mL of a mixed solvent in which a ratio of toluene to distilled water was 4/1, and then stirred at a temperature of 80° C. for 18 hours. An organic layer was extracted from the reaction mixture by using dichloromethane and distilled water. The extracted organic layer was dried by using magnesium sulfate and then filtered. Then, the residue obtained therefrom was purified by column chromatography (1/30=methanol/dichloromethane) to obtain 1.7 g of Intermediate B.

c) Synthesis of Intermediate C

1.7 g (3.82 mmol) of Intermediate B was dissolved in 150 mL of dichloromethane and cooled to a temperature of −78° C. 7.83 mL (7.83 mmol) of BBr3(1.0 M in n-hexane) was added thereto, stirred for 1 hour, heated to a temperature of 0° C., and then stirred for 2 hours. The reaction was terminated by a sodium bicarbonate aqueous solution, and an organic layer was extracted therefrom by using dichloromethane. The extracted organic layer was dried by magnesium sulfate and then filtered. Then, the residue obtained therefrom was purified by column chromatography (1/2=ethyl acetate/normal hexane) to obtain 1.3 g of Intermediate C.

d) Synthesis of Intermediate D

1.2 g (2.79 mmol) of Intermediate C, 1.0 g (3.20 mmol) of 2-bromo-9-(pyridin-2-yl)-carbazole, 0.14 g (1.06 mmol) of picolinic acid, 0.11 g (0.53 mmol) of copper(I) iodide, and 1.14 g (5.58 mmol) of potassium phosphate were added to a round-bottom flask and suspended in 100 mL of dimethylsulfoxide. The reaction mixture was heated to a temperature of 120° C. and stirred for 20 hours. An organic layer was extracted from the reaction mixture by using ethyl acetate and distilled water. The extracted organic layer was dried by using magnesium sulfate and then filtered. Then, the residue obtained therefrom was purified by column chromatography (1/1=ethyl acetate/normal hexane) to obtain 1.0 g of Intermediate D.

e) Synthesis of Compound 28

0.35 g (0.52 mmol) of Intermediate D, 0.23 g (0.54 mmol) of potassium tetrachloroplatinate, and 0.017 g (0.052 mmol) of Bu4NBr were suspended in 30 mL of acetic acid. The reaction solution was bubbled with nitrogen for 30 minutes and stirred at room temperature for 8 hours. The reaction mixture was heated to a temperature of 120° C. and additionally stirred for 36 hours. Then, the reaction mixture was cooled to room temperature, and 100 mL of distilled water was added thereto. A precipitate was filtered therefrom, washed three times by using distilled water, and then dried with warm air. Then, a solid obtained therefrom was purified by column chromatography (1/1=dichloromethane/normal hexane) to obtain 0.24 g of Compound 28.

Synthesis Example 4: Synthesis of Compound 17

0.85 g of Compound 17 was synthesized in substantially the same manner as in Synthesis Example 3, except that 2-(3-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)-5-(1-methyl-1H-imidazol-2-yl)phenoxy)-9-(pyridin-2-yl)-9H-carbazole was used instead of Intermediate D.

Synthesis Example 5: Synthesis of Compound 22

1.00 g of Compound 22 was synthesized in substantially the same manner as in Synthesis Example 3, except that 2-(3-(3-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)-5-(1-methyl-1H-314-imidazol-3-yl)phenoxy)phenoxy)pyridine was used instead of Intermediate D.

Synthesis Example 6: Synthesis of Compound 24

1.28 g of Compound 24 was synthesized in substantially the same manner as in Synthesis Example 3, except that N-(3-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)-5-((9-(pyridin-2-yl)-9H-carbazol-2-yl)oxy)phenyl)-N-phenylpyridin-2-amine was used instead of Intermediate D.

Synthesis Example 7: Synthesis of Compound 26

0.55 g of Compound 26 was synthesized in substantially the same manner as in Synthesis Example 3, except that 2-(3-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)-5-(1-methyl-1H-imidazol-2-yl)phenoxy)-9-(1-methyl-1H-imidazol-2-yl)-9H-carbazole was used instead of Intermediate D.

Synthesis Example 8: Synthesis of Compound 2

1.05 g of Compound 40 was synthesized in substantially the same manner as in Synthesis Example 3, except that 9-(4-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)pyridin-2-yl)-2-((9-(4-methylpyridin-2-yl)-9H-carbazol-2-yl)oxy)-9H-carbazole was used instead of Intermediate D.

Synthesis Example 9: Synthesis of Compound 41

0.88 g of Compound 41 was synthesized in substantially the same manner as in Synthesis Example 3, except that ((9-(4-phenylpyridin-2-yl)-9H-carbazol-2-yl)oxy)-9H-carbazole was used instead of Intermediate D.

Synthesis Example 10: Synthesis of Compound 42

0.85 g of Compound 42 was synthesized in substantially the same manner as in Synthesis Example 3, except that 9-(4-(3,5-dimethyl-1-phenyl-1H-pyrazol-4-yl)pyridin-2-yl)-2-((9-(4-isopropylpyridin-2-yl)-9H-carbazol-2-yl)oxy)-9H-carbazole was used instead of Intermediate D.

High resolution electron impact mass spectrometry (HR-EIMS) values and1H nuclear magnetic resonance (NMR) measurement results measured for the Synthesis Examples are shown in Table 1 below.

As a substrate and an ITO anode, a Corning 15 Ω/cm2(1,200 Å) ITO glass substrate was cut to a size of 50 mm×50 mm×0.7 mm, sonicated with isopropyl alcohol and pure water each for 5 minutes, and then cleaned by exposure to ultraviolet rays and ozone for 30 minutes. Then, the resultant ITO glass substrate was provided to a vacuum deposition apparatus.

2-TNATA was vacuum-deposited on the ITO anode formed on the ITO glass substrate to form a hole injection layer having a thickness of 600 Å, and NPB was vacuum-deposited on the hole injection layer to form a hole transport layer having a thickness of 300 Å.

BCPDS (bis(4-(9H-carbazol-9-yl)phenyl)diphenylsilane) and POPCPA ((4-{1-[4-(diphenylphosphoryl)phenyl]cyclohexyl}phenyl)diphenylamine) (co-host) (weight ratio of BCPDS to POPCPA was 1:1), and Compound 1 (dopant), were co-deposited on the hole transport layer at a weight ratio of the co-host to the dopant of 90:10, thereby forming an emission layer having a thickness of 300 Å.

TSPO1 (diphenyl-4-triphenylsilyl-phenylphosphine oxide) was deposited on the emission layer to form a hole blocking layer having a thickness of 50 Å, Alq3was deposited on the hole blocking layer to form an electron transport layer having a thickness of 300 Å, LiF was deposited on the electron transport layer to form an electron injection layer having a thickness of 10 Å, and Al was vacuum-deposited on the electron injection layer to form a cathode having a thickness of 3,000 Å, thereby completing the manufacture of an organic light-emitting device.

Examples 2 to 10 and Comparative Examples 1 to 4

Organic light-emitting devices were manufactured in substantially the same manner as in Example 1, except that Compounds shown in Table 2 were each used instead of Compound 1 as a dopant in forming an emission layer.

Evaluation Example 1

The driving voltage, current density, luminance, luminescent efficiency, and maximum emission wavelength of the organic light-emitting devices manufactured according to Examples 1 to 10 and Comparative Examples 1 to 4 were measured by using Keithley SMU 236 and a luminance meter PR650, and evaluation results thereof are shown in Table 2.

Referring to Table 2, it is confirmed that the organic light-emitting devices of Examples 1 to 10 have a low driving voltage, high luminance, and high luminescent efficiency, and are suitable for deep blue light emission, as compared with those of the organic light-emitting devices of Comparative Examples 1 to 4.

According to one or more embodiments, an organic light-emitting device including the organometallic compound may have a low driving voltage, high luminescent efficiency, high luminance, and a long lifespan.

As used herein, the terms “combination thereof” and “combinations thereof” may refer to a chemical combination (e.g., an alloy or chemical compound), a mixture, or a laminated structure of components.