Organic light-emitting device

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 a hole transport region between the first electrode and the emission layer, the hole transport region including at least one selected from a hole transport layer, a hole injection layer, and a buffer layer, and an electron transport region between the emission layer and the second electrode, the electron transport region including at least one selected from a hole blocking layer, an electron transport layer, and an electron injection layer, wherein the electron transport region includes a compound represented by Formula 1 and a compound represented by Formula 2

CROSS-REFERENCE TO RELATED APPLICATION

Korean Patent Application No. 10-2014-0158902, filed on Nov. 14, 2014, in the Korean Intellectual Property Office, and entitled: “Organic Light-Emitting Device,” is incorporated by reference herein in its entirety.

BACKGROUND

Embodiments relate to an organic light-emitting device.

2. Description of the Related Art

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

SUMMARY

Embodiments are directed to an organic light-emitting device.

The embodiments may be realized by providing 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 a hole transport region between the first electrode and the emission layer, the hole transport region including at least one selected from a hole transport layer, a hole injection layer, and a buffer layer, and an electron transport region between the emission layer and the second electrode, the electron transport region including at least one selected from a hole blocking layer, an electron transport layer, and an electron injection layer, wherein the electron transport region includes a compound represented by Formula 1 and a compound represented by Formula 2:

wherein, in Formula 1, R1, R2, and Ar are each independently selected from a hydrogen, a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a substituted or unsubstituted C1-C60alkyl group, a substituted or unsubstituted C2-C60alkenyl group, a substituted or unsubstituted C2-C60alkynyl group, a substituted or unsubstituted C1-C60alkoxy group, a substituted or unsubstituted C3-C10cycloalkyl group, a substituted or unsubstituted C1-C10heterocycloalkyl group, a substituted or unsubstituted C3-C10cycloalkenyl group, a substituted or unsubstituted C2-C10heterocycloalkenyl group, a substituted or unsubstituted C6-C60aryl group, a substituted or unsubstituted C6-C60aryloxy group, a substituted or unsubstituted C6-C60arylthio group, a substituted or unsubstituted 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), and —B(Q6)(Q7); L is selected from a substituted or unsubstituted C3-C10cycloalkylene group, a substituted or unsubstituted C2-C10heterocycloalkylene group, a substituted or unsubstituted C3-C10cycloalkenylene group, a substituted or unsubstituted C2-C10heterocycloalkenylene group, a substituted or unsubstituted C6-C60arylene group, a substituted or unsubstituted C1-C60heteroarylene group, a substituted or unsubstituted divalent non-aromatic condensed polycyclic group, and a substituted or unsubstituted divalent non-aromatic condensed heteropolycyclic group; m and n are each independently an integer selected from 1 to 4; a is an integer selected from 0 to 2; b is an integer selected from 1 and 2; when m or n are 2 or more, each R1or R2is identical to or different from each other;

The electron transport layer may include the compound represented by Formula 1 and the compound represented by Formula 2.

The electron transport layer may include at least one selected from a first electron transport layer a second electron transport layer, and a third electron transport layer.

The electron transport layer may include a first electron transport layer and a second electron transport layer, the first electron transport layer may include the compound represented by Formula 1, and the second electron transport layer may include the compound represented by Formula 2.

The electron transport layer may include a first electron transport layer and a second electron transport layer, the first electron transport layer may include the compound represented by Formula 2, and the second electron transport layer may include the compound represented by Formula 1.

R1and R2may each independently be selected from a hydrogen and a deuterium.

L may be selected from a substituted or unsubstituted C6-C60arylene group and a substituted or unsubstituted divalent non-aromatic condensed polycyclic group.

Ar may be selected from a substituted or unsubstituted C6-C60aryl group and a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group.

L may be a group represented by one of the following Formulae 2a and 2b:

wherein, in Formulae 2a and 2b, * indicates a binding site to a neighboring atom.

Ar may be a group represented by one of the following Formulae 3a to 3c:

wherein, in Formulae 3a to 3c, Z1may be selected from a hydrogen, a deuterium, a substituted or unsubstituted C1-C20alkyl group, a substituted or unsubstituted C6-C20aryl group, a substituted or unsubstituted C1-C20heteroaryl group, a halogen group, a cyano group, a nitro group, a hydroxyl group, and a carboxyl group; p may be an integer selected from 1 to 9; and * indicates a binding site to a neighboring atom.

The compound represented by Formula 1 may be one of the following Compounds 1-1 to 1-10:

R11, R12, R19to R21, R28to R30, and R37may each independently be selected from a hydrogen and a deuterium.

R13to R18, R22to R27, and R31to R36may each independently be selected from a hydrogen, a deuterium, a substituted or unsubstituted C1-C20alkyl group, and a substituted or unsubstituted C6-C20aryl group.

R13to R18, R22to R27, and R31to R36may each independently be selected from a hydrogen, a deuterium, a methyl group, and a phenyl group.

The compound represented by Formula 2 may be one of the following Compounds 2-1 to 2-4:

The electron transport region may include a metal complex.

The metal complex may be a lithium complex.

The metal complex may be selected from a lithium quinolate and the following compound ET-D2.

The organic layer may be formed by using a wet method.

The embodiments may be realized by providing a flat panel display apparatus including a thin film transistor, the thin film transistor including a source electrode and a drain electrode; and the organic light-emitting device according to an embodiment, wherein the first electrode of the organic light-emitting device is electrically connected to the source electrode or the drain electrode of the thin film transistor.

DETAILED DESCRIPTION

In the drawing FIGURE, the dimensions of layers and regions may be exaggerated for clarity of illustration. Like reference numerals refer to like elements throughout.

According to an embodiment, an organic light-emitting device may include a first electrode; a second electrode facing the first electrode; and an organic layer between the first electrode and the second electrode and including an emission layer.

The organic layer may include, e.g., i) a hole transport region that is disposed between the first electrode and the emission layer and includes at least one selected from a hole transport layer, a hole injection layer and a buffer layer, and ii) an electron transport region that is disposed between the emission layer and the second electrode and includes at least one selected from a hole blocking layer, an electron transport layer, and an electron injection layer.

The electron transport region may include, e.g., a compound represented by Formula 1 and a compound represented by Formula 2 below.

In Formula 1,

m and n may each independently be an integer selected from 1 to 4;

a may be an integer selected from 0 to 2; and

b may be an integer selected from 1 and 2.

When m or n are 2 or more, each R1or R2may be identical to or different from each other.

In Formula 2,

The compound represented by Formula 1 according to an embodiment may have a pyridine-pyridine structure, which has high molecular polarity, thereby having an excellent electron transport ability.

However, when an organic light-emitting device is being driven, Joule heat may be generated or polaron quenching may occur. Due to the Joule heat or polaron quenching, a pyridine-pyridine structure may be easily broken. This may adversely affect the lifespan of the organic light-emitting device. Thus, an organic light-emitting device including the compound represented by Formula 1 (e.g., alone) may not have satisfying lifespan characteristics.

The compound represented by Formula 2 is a triazine-based or triazine-containing compound, and may have a high electric stability and a low level of the highest occupied molecular orbital (HOMO) energy level, which is a common feature of triazine-based molecules. The compound represented by Formula 2, therefore, may have an excellent hole blocking ability, a high glass transition temperature, and crystallization prevention characteristics.

The compound represented by Formula 2 may have a relatively low efficiency when it comes to injection of electrons from the cathode, and low stability in its cation state, although its hole blocking ability may be excellent. Therefore, an organic light-emitting device having the compound represented by Formula 2 (e.g., alone) may not have satisfying lifespan characteristics.

According to an exemplary embodiment, the compound represented by Formula 1 and the compound represented by Formula 2 may be used together to form an electron transport layer to thereby overcome the individual effects of each of the compounds described above, and may produce a synergistic effect. Thus, the manufactured organic light-emitting device has excellent lifespan characteristics as well as a high efficiency and a low driving voltage.

In an implementation, the electron transport layer of the organic light-emitting device may include the compound represented by Formula 1 and the compound represented by Formula 2.

In an implementation, the electron transport layer of the organic light-emitting device may be formed in or include a plurality of layers. In an implementation, the electron transport layer may include at least one selected from a first electron transport layer and a second electron transport layer; and a third electron transport layer.

In an implementation, the electron transport layer of the organic light-emitting device may include the first electron transport layer and the second electron transport layer, the first electron transport layer may include the compound represented by Formula 1, and the second electron transport layer may include the compound represented by Formula 2.

In an implementation, the first electron transport layer may include the compound represented by Formula 2, and the second electron transport layer may include the compound represented by Formula 1.

In an implementation, R1and R2may each independently be selected from a hydrogen and a deuterium, e.g., may each independently be hydrogen or deuterium.

In an implementation, L may be selected from or include, e.g., a substituted or unsubstituted C6-C60arylene group and a substituted or unsubstituted divalent non-aromatic condensed polycyclic group.

In an implementation, Ar may be selected from or include, e.g., a substituted or unsubstituted C6-C60aryl group and a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group.

In an implementation, L may be any a group represented by one of the following Formulae 2a and 2b.

In Formulae 2a and 2b, * indicates a binding site to a neighboring atom.

In an implementation, Ar may be a group represented by one of the following Formulae 3a to 3c.

In Formulae 3a to 3c, Z1may be selected from or include, e.g., a hydrogen, a deuterium, a substituted or unsubstituted C1-C20alkyl group, a substituted or unsubstituted C6-C20aryl group, a substituted or unsubstituted C1-C20heteroaryl group, a halogen group, a cyano group, a nitro group, a hydroxyl group, and a carboxyl group;

p may be an integer selected from 1 to 9; and * indicates a binding site to a neighboring atom.

In an implementation, the compound represented by Formula 1 may be, e.g., one of the following Compounds 1-1 to 1-10.

In an implementation, R11, R12, R19to R21, R28to R30, and R37may each independently be selected from, e.g., a hydrogen and a deuterium.

In an implementation, R13to R18, R22to R27, and R31to R36may each independently be selected from or include, e.g., a hydrogen, a deuterium, a substituted or unsubstituted C1-C20alkyl group, and a substituted or unsubstituted C6-C20aryl group.

In an implementation, R13to R18, R22to R27, and R31to R36may each independently be selected from, e.g., a hydrogen, a deuterium, a methyl group, and a phenyl group.

In an implementation, the compound represented by Formula 2 may be, e.g., one of the following Compounds 2-1 to 2-4.

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

FIG. 1illustrates a schematic view of an organic light-emitting device10according to an embodiment. The organic light-emitting device10may include a first electrode110, an organic layer150, and a second electrode190.

Hereinafter, a structure and a method of manufacturing the organic light-emitting device according to an embodiment will be described with reference toFIG. 1.

Referring toFIG. 1, a substrate may be additionally disposed under the first electrode110or on the second electrode190. The substrate may be a glass substrate or transparent plastic substrate, each with excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and water resistance.

The first electrode110may be formed by depositing or sputtering a material for forming the first electrode on the substrate. When the first electrode110is an anode, the material for the first electrode may be selected from materials with a high work function to facilitate hole injection. The first electrode110may be a reflective electrode, a semi-transmissive electrode, or a transmissive electrode. The material for the first electrode may be a transparent and highly conductive material. Examples of such a material may include indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO2), and zinc oxide (ZnO). When the first electrode110is a semi-transmissive electrode or a reflective electrode, as a material for forming the first electrode, at least one selected from magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), and magnesium-silver (Mg—Ag) may be used.

The first electrode110may have a single-layer structure, or a multi-layer structure including a plurality of layers. For example, the first electrode110may have a triple-layer structure of ITO/Ag/ITO.

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

The hole transport region may include, e.g., at least one selected from a hole injection layer (HIL), a hole transport layer (HTL), and a buffer layer. The electron transport region may include, e.g., at least one selected from a hole blocking layer (HBL), an electron transport layer (ETL), and an electron injection layer (EIL).

The hole transport region may have a single-layered structure formed of a single material, a single-layered structure formed of a plurality of different materials, or a multi-layered structure having a plurality of layers formed of a plurality of different materials.

For example, the hole transport region may have a single-layered structure formed of a plurality of different materials, or a structure of hole injection layer/hole transport layer, a structure of hole injection layer/hole transport layer/buffer layer, a structure of hole injection layer/buffer layer, a structure of hole transport layer/buffer layer, or a structure of hole injection layer/hole transport layer/electron blocking layer, wherein layers of each structure are sequentially stacked from the first electrode110in this stated order.

When the hole transport region includes a hole injection layer, the hole injection layer may be formed on the first electrode110by using various methods, e.g., vacuum-deposition, spin coating, casting, Langmuir-Blodgett (LB) method, ink-jet printing, laser-printing, or laser-induced thermal imaging (LITI).

When a hole injection layer is formed by vacuum-deposition, e.g., the vacuum-deposition may be performed at a temperature of a deposition temperature in a range of about 100° C. to about 500° C., at a vacuum degree in a range of about 10−8torr to about 10−3torr, and/or at a deposition rate in a range of about 0.01 Å/sec to about 100 Å/sec in consideration of a compound for a hole injection layer to be deposited, and the structure of a hole injection layer to be formed.

When a hole injection layer is formed by spin coating, the spin coating may be performed at a coating rate in a range of about 2,000 rpm to about 5,000 rpm, and/or at a temperature in a range of about 80° C. to 200° C. in consideration of a compound for a hole injection layer to be vacuum-deposited, and the structure of a hole injection layer to be formed.

When the hole transport region includes a hole transport layer, the hole transport layer may be formed on the first electrode110or the hole injection layer by using various methods, e.g., vacuum-deposition, spin coating, casting, LB method, ink-jet printing, laser-printing, or LITI. When the hole transport layer is formed by vacuum-deposition or spin coating, conditions for vacuum-deposition and coating may be similar to the above-described vacuum-deposition and coating conditions for forming the hole injection layer.

In Formulae 201 and 202,

L201to L205may be the same as defined in connection with L provided herein;

xa1 to xa4 may each independently be selected from 0, 1, 2, and 3; and

In some embodiments, in Formulae 201 and 202,

xa1 to xa4 may each independently be selected from 0, 1, and 2;

xa5 may be selected from 1, 2, and 3;

In an implementation, the compound represented by Formula 201 may be represented by Formula 201A.

In an implementation, the compound represented by Formula 201 may be represented by Formula 201 A-1.

In an implementation, the compound represented by Formula 202 may be represented by Formula 202A.

In an implementation, in Formulae 201A-1 and 202A,

xa1 to xa3 may each independently be selected from 0 and 1;

a C1-C20alkyl group and a C1-C20alkoxy group;

xa5 may be selected from 1 and 2.

In an implementation, in Formulae 201A and 201A-1, R213and R214may link to each other so as to form a saturated ring or an unsaturated ring.

The compound represented by Formula 201 and the compound represented by Formula 202 may include, e.g., one of the following Compounds HT1 to HT20.

A thickness of the hole transport region may be in a range of about 100 Å to about 10,000 Å, e.g., about 100 Å to about 1,000 Å. When the hole transport region includes the a hole injection layer and a hole transport layer, a thickness of the hole injection layer may be in a range of about 100 Å to about 10,000 Å, e.g., about 100 Å to about 1,000 Å, a thickness of the hole transport layer may be in a range of about 50 Å to about 2,000 Å, e.g., about 100 Å to about 1,500 Å. When the thicknesses of the hole transport region, the hole injection layer, and the hole transport layer are within these ranges, excellent hole transport characteristics may be obtained without a substantial increase in driving voltage.

The hole transport region may further include, in addition to the mentioned materials above, a charge-generating material to improve conductive properties. The charge-generating material may be homogeneously or non-homogeneously dispersed throughout the hole transport region.

The hole transport region may further include a buffer layer as well as the electron blocking layer, hole injection layer, and hole transport layer described above. The buffer layer may compensate for an optical resonance distance according to a wavelength of light emitted from the emission layer, and light-emission efficiency of a formed organic light-emitting device may be improved. For use as a material included in the buffer layer, materials that are included in the hole transport region may be used. The electron blocking layer prevents injection of electrons from the electron transport region.

An emission layer may be formed on the first electrode110or the hole transport region by using various methods, e.g., vacuum-deposition, spin coating, casting, LB method, ink-jet printing, laser-printing, or LITI. When the emission layer is formed by vacuum-deposition or spin coating, deposition and coating conditions for the emission layer may be determined by referring to the deposition and coating conditions for the hole injection layer.

When the organic light-emitting device10is a full color organic light-emitting device, the emission layer may be patterned into a red emission layer, a green emission layer, or a blue emission layer, according to a sub pixel. In an implementation, the emission layer may have a stacked structure of a red emission layer, a green emission layer, and a blue emission layer, or may include a red-light emission material, a green-light emission material, and a blue-light emission material, which are mixed with each other in a single layer, to emit white light.

The emission layer may include a host and a dopant.

For example, the host may include at least one selected from TPBi, TBADN, ADN (also known as “DNA”), CBP, CDBP, and TCP.

In an implementation, the host may further include a compound represented by Formula 301:
Ar301-[(L301)xb1-R301]xb2<Formula 301>

In Formula 301,

a naphthalene, a heptalene, a fluorene, a spiro-fluorene, a benzofluorene, a dibenzofluorene, a phenalene, a phenanthrene, an anthracene, a fluoranthene, a triphenylene, a pyrene, a chrysene, a naphthacene, a picene, a perylene, a pentaphene and an indenoanthracene, each substituted with at least one selected from a deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphoric acid or a salt thereof, a C1-C60alkyl group, a C2-C60alkenyl group, a C2-C60alkynyl group, a C1-C60alkoxy group, a C3-C10cycloalkyl group, a C1-C10heterocycloalkyl group, a C3-C10cycloalkenyl group, a C2-C10heterocycloalkenyl group, a C6-C60aryl group, a C6-C60aryloxy group, a C6-C60arylthio group, a C1-C60heteroaryl group, a monovalent non-aromatic condensed polycyclic group, a monovalent non-aromatic condensed heteropolycyclic group, and —Si(Q301)(Q302)(Q303) (Q301to Q303may be each independently selected from a hydrogen, a C1-C60alkyl group, a C2-C60alkenyl group, a C6-C60aryl group, and a C1-C60heteroaryl group);

The descriptions for L301may be the same as defined in connection with L201herein;

a C1-C20alkyl group and a C1-C20alkoxy group;

xb1 may be selected from 0, 1, 2, and 3; and

xb2 may be selected from 1, 2, 3, and 4.

In an implementation, in Formula 301,

a C1-C20alkyl group and a C1-C20alkoxy group;

In an implementation, the host may include a compound represented by Formula 301A.

The descriptions for Formula 301A may be understood by referring to the descriptions provided herein.

The compound represented by Formula 301 may include, e.g., one of the following Compounds H1 to H42.

The dopant may include a suitable fluorescent dopant or a suitable phosphorescent dopant.

The phosphorescent dopant may include, e.g., an organometallic complex represented by Formula 401 below.

In Formula 401,

Ring A401and Ring A402may each independently be selected from or include, e.g., a substituted or unsubstituted benzene, a substituted or unsubstituted naphthalene, a substituted or unsubstituted fluorene, a substituted or unsubstituted spiro-fluorene, a substituted or unsubstituted indene, a substituted or unsubstituted pyrrole, a substituted or unsubstituted thiophene, a substituted or unsubstituted furan, a substituted or unsubstituted imidazole, a substituted or unsubstituted pyrazole, a substituted or unsubstituted thiazole, a substituted or unsubstituted isothiazole, a substituted or unsubstituted oxazole, a substituted or unsubstituted isoxazole, a substituted or unsubstituted pyridine, a substituted or unsubstituted pyrazine, a substituted or unsubstituted pyrimidine, a substituted or unsubstituted pyridazine, a substituted or unsubstituted quinoline, a substituted or unsubstituted isoquinoline, a substituted or unsubstituted benzoquinoline, a substituted or unsubstituted quinoxaline, a substituted or unsubstituted quinazoline, a substituted or unsubstituted carbazole, a substituted or unsubstituted benzoimidazole, a substituted or unsubstituted benzofuran, a substituted or unsubstituted benzothiophene, a substituted or unsubstituted isobenzothiophene, a substituted or unsubstituted benzoxazole, a substituted or unsubstituted isobenzoxazole, a substituted or unsubstituted triazole, a substituted or unsubstituted oxadiazole, a substituted or unsubstituted triazine, a substituted or unsubstituted dibenzofuran, and a substituted or unsubstituted dibenzothiophene.

L401may be an organic ligand;

xc1 may be 1, 2, or 3; and

In an implementation, when A401in Formula 401 has a plurality of substituents, the plurality of substituents of A401may bind to each other to form a saturated or unsaturated ring.

In an implementation, when A402in Formula 401 has a plurality of substituents, the plurality of substituents of A402may bind to each other to form a saturated or unsaturated ring.

In an implementation, when xc1 in Formula 401 is two or more, a plurality of ligands

in Formula 401 may be identical or different. In Formula 401, when xc1 is 2 or more, A401and A402may be directly connected or connected via a linking group (for example, a C1-C5alkylene group, —N(R′)— (here, R′ is a C1-C10alkyl group or a C6-C20aryl group), or —C(═O)—) to one other adjacent ligand of A401and A402respectively.

The phosphorescent dopant may include, e.g., at least one selected from Compounds PD1 to PD74 below.

An amount of the dopant in the emission layer may be, e.g., in a range of about 0.01 to about 15 parts by weight, based on 100 parts by weight of the host.

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

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

When the electron transport region includes a hole blocking layer, the hole blocking layer may be formed on the emission layer by using various methods, e.g., vacuum-deposition, spin coating, casting, LB method, ink-jet printing, laser-printing, or LITI. When the hole blocking layer is formed by vacuum-deposition or spin coating, deposition and coating conditions for the hole blocking layer may be determined by referring to the deposition and coating conditions for the hole injection layer.

In an implementation, the hole blocking layer may include, e.g., at least one selected from BCP and Bphen.

A thickness of the hole blocking layer may be in a range of about 20 Å to about 1,000 Å, e.g., about 30 Å to about 300 Å. When the thickness of the hole blocking layer is within this range, excellent hole blocking characteristics may be obtained without a substantial increase in driving voltage.

The electron transport region may have a structure of, e.g., electron transport layer/electron injection layer or a structure of hole blocking layer/electron transport layer/electron injection layer, wherein layers of each structure are sequentially stacked from the emission layer in the stated order. The electron transport layer may be formed of a plurality of layers. In an implementation, the electron transport layer may include at least one selected from a first electron transport layer and a second electron transport layer, and a third electron transport layer. In an implementation, the electron transport layer may include a third electron transport layer, and at least one of a first electron transport layer and a second electron transport layer. In an implementation, the electron transport layer may include, e.g., any of a first electron transport layer, a second electron transport layer, and/or a third electron transport layer. In an implementation, the first electron transport layer, the second electron transport layer, and/or the third electron transport layer may each independently include materials that are different from one another.

In an implementation, the organic layer150of the organic light-emitting device may include an electron transport region between the emission layer and the second electrode190, and the electron transport region may include the compound represented by Formula 1 and the compound represented by Formula 2. In an implementation, the electron transport layer may include the first electron transport layer and the second electron transport layer. In an implementation, the first electron transport layer may include the compound represented by Formula 1, and the second electron transport layer may include compound represented by Formula 2. In an implementation, the first electron transport layer may include the compound represented by Formula 2, and the second electron transport layer may include the compound represented by Formula 1.

A thickness of the electron transport layer may be in a range of about 100 Å to about 1000 Å, for example, about 150 Å to about 500 Å. When the thickness of the electron transport layer is within this range, excellent electron transport characteristics may be obtained without a substantial increase in driving voltage.

In an implementation, the electron transport layer may further include a metal-containing material, in addition to the materials described above.

The metal-containing material may include a lithium (Li) complex. In an implementation, the Li complex may include, e.g., Compound ET-D1 (lithium quinolate, LiQ) or Compound ET-D2.

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

The electron injection layer may be formed on the electron transport layer by using various methods, such as vacuum-deposition, spin coating, casting, LB method, ink-jet printing, laser-printing, or LITI. When the electron injection layer is formed by vacuum-deposition or spin coating, vacuum-deposition and coating conditions for the electron injection layer may be determined by referring to the vacuum-deposition and coating conditions for the hole injection layer.

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

The second electrode190may be disposed on the organic layer150. The second electrode190may be a cathode that is an electron injection electrode, and in this regard, a material for forming the second electrode190may be a material having a low work function, and such a material may be metal, alloy, an electrically conductive compound, or a mixture thereof. Examples of the material for the second electrode190may include lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), or magnesium-silver (Mg—Ag). In an implementation, the material for forming the second electrode190may be, e.g., ITO or IZO. The second electrode190may be a reflective electrode, a semi-transmissive electrode, or a transmissive electrode.

The organic layer of the organic light-emitting device according to an embodiment may be formed by vacuum-depositing the compound according to an embodiment or using wet method in which the compound according to an embodiment is prepared in the form of solution, and then the solution of the compound is used for coating.

The organic light-emitting device according to an embodiment may be included in a variety type of flat panel display apparatuses, e.g., a passive matrix organic light-emitting display apparatus and an active matrix organic light-emitting display apparatus. Particularly, when the organic light-emitting device is included in an active matrix organic light-emitting display apparatus, a first electrode disposed on a substrate is a pixel electrode, and the first electrode may be electrically connected to a source electrode or drain electrode of a thin film transistor. In addition, the organic light-emitting device may be included in a flat panel display apparatus that may display images on both sides.

Hereinbefore, the organic light-emitting device has been described with reference toFIG. 1.

Hereinafter, definitions of substituents used herein will be presented (the number of carbon numbers used to restrict a substituent is not limited, and does not limit properties of the substituent, and unless defined otherwise, the definition of the substituent is consistent with a general definition thereof).

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

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

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

A C3-C10cycloalkyl group used herein refers to a monovalent monocyclic saturated hydrocarbon group including 3 to 10 carbon atoms, and detailed examples thereof are a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group. A C3-C10cycloalkylene group used herein refers to a divalent group having the same structure as a C3-C10cycloalkyl group.

A C1-C10heterocycloalkyl group used herein refers to a monovalent monocyclic group including at least one hetero atom selected from N, O, P, and S as a ring-forming atom and 1 to 10 carbon atoms, and detailed examples thereof are a tetrahydrofuranyl group and a tetrahydrothiophenyl group. A C2-C10heterocycloalkylene group used herein refers to a divalent group having the same structure as a C1-C10heterocycloalkyl group.

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

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

A C6-C60aryl group used herein refers to a monovalent group including a carbocyclic aromatic system having 6 to 60 carbon atoms, and a C6-C60arylene group used herein refers to a divalent group including a carbocyclic aromatic system having 6 to 60 carbon atoms. Detailed examples of the C6-C60aryl group are a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a pyrenyl group, and a chrysenyl group. When the C6-C60aryl group and the C6-C60arylene group each include a plurality of rings, the rings may be fused to each other.

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

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

“Ph” used herein refers to a phenyl group, “Me” refers to a methyl group, “Et” refers to an ethyl group, and “ter-Bu” or “But” refers to a tert-butyl group.

Hereinafter, an organic light-emitting device according to an embodiment will be described in detail with reference to Examples.

A Corning 15 Ω/cm2(500 Å) ITO glass substrate was cut to a size of 50 mm×50 mm×0.5 mm, and then, sonicated by using isopropyl alcohol and pure water for 10 minutes respectively, and cleaned by exposure to ultraviolet rays with ozone for 10 minutes, and then, the glass substrate was mounted to a vacuum-deposition apparatus so as to use the glass substrate as an anode.

2-TNATA (available from Duksan Hi Metal Co., Ltd), was vacuum-deposited on the glass substrate to form a hole injection layer having a thickness of about 600 Å. Thereafter, 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB) (available from Duksan Hi Metal Co., Ltd), was vacuum-deposited as a hole transporting compound on the hole injection layer to form a hole transport layer having a thickness of about 300 Å.

Alq3(available from Duksan Hi Metal Co., Ltd) as an emission host and Ir(ppy)3[bis-(1-phenylisoquinolyl)iridium(III)acetylacetonate as a green phosphorescent dopant were co-deposited in a weight ratio of about 90:10 on the hole transport layer to form an emission layer having a thickness of about 400 Å.

Subsequently, Compound 2-1 was vacuum-deposited on the emission layer to form a first electron transport layer having a thickness of about 150 Å, and then, Compound 1-1 was vacuum-deposited on the first electron transport layer to form a second electron transport layer having a thickness of about 150 Å. Afterward, aluminum (Al) was vacuum-deposited on the electron transport layer having a thickness of about 2,000 Å, thereby completing the manufacture of an organic light-emitting device.

An organic light-emitting device was manufactured in the same manner as in Example 1, except that Compound 2-1 was vacuum-deposited on the emission layer to form a first electron transport layer having a thickness of about 140 Å, and Compound 1-1 was vacuum-deposited on the first electron layer to form a second electron transport layer having a thickness of about 140 Å, and then, lithium quinolate (LiQ) was vacuum-deposited on the second electron transport layer to form a third electron transport layer having a thickness of about 20 Å.

Examples 3 to 16

Organic light-emitting devices were manufactured in the same manner as in Example 1, following the conditions shown in Table 1.

Comparative Examples 1 to 6-1

Organic light-emitting devices were manufactured in the same manner as in Example 1, following the conditions shown in Table 1.

Referring to Table 1, the organic light-emitting device according to Examples 1 to 16 exhibited excellent emission characteristics, compared to the organic light emitting devices prepared in the Comparative Examples.

When the compound represented by Formula 1 and the compound represented by Formula 2 are used together in an organic light-emitting device, the organic light-emitting device may have an excellent lifespan characteristics, compared to an organic light-emitting device in which the compound represented by Formula 1 or the compound represented by Formula 2 is used alone. As described above, when the compound represented by Formula 1 and the compound represented by Formula 2 are used together in an organic light-emitting device, drawbacks of each electron transporting material may be overcome, and the compounds represented by Formula 1 and 2 may produce an unexpected synergistic effect.

The compound represented by Formula 1 may be unstable in its cation state, however, by disposing the compound represented by Formula 2 having a relatively stable electronic characteristics adjacent to the compound represented by Formula 1, electronic stress may be relieved. Furthermore, the compound represented by Formula 2 may still have excellent electron injection characteristics, which may enable the organic light-emitting device to have an improved lifespan.

As described above, according to the one or more of the above exemplary embodiments, the organic light-emitting device has a long lifespan while maintaining an improved efficiency.

The embodiments may provide an organic light-emitting device having both a long lifespan and improved efficiency.