Organic light-emitting device and apparatus including the same

An organic light-emitting device includes: a first electrode; a second electrode facing the first electrode; and an organic layer located between the first electrode and the second electrode and including an emission layer, wherein the emission layer includes a host and a dopant, the host includes a first compound and a second compound, and the first compound, the second compound, and the dopant are different from one another. Two compounds in the host included in the emission layer may have different HOMO and LUMO energy levels and may form an exciplex, and a difference between a HOMO energy level and a LUMO energy level of the exciplex (ΔEexciplex) may be greater than a difference between a HOMO energy level and a LUMO energy level of the dopant (ΔEdopant).

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2020-0040483, filed on Apr. 2, 2020, in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference.

BACKGROUND

One or more aspects of embodiments of the present disclosure relate to an organic light-emitting device and an organic light-emitting display apparatus including the same.

2. Description of 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/or excellent characteristics in terms of brightness, driving voltage, and/or response speed, compared to devices in the related art.

SUMMARY

One or more aspects of embodiments of the present disclosure are directed toward a high-quality organic light-emitting device having low driving voltage, high efficiency, and/or long lifespan.

One or more example embodiments of the present disclosure provide an organic light-emitting device including:

a first electrode,

a second electrode facing the first electrode, and

an organic layer located between the first electrode and the second electrode and including an emission layer,

wherein the emission layer includes a host and a dopant,

the host includes a first compound and a second compound,

the first compound, the second compound, and the dopant are different from one another,

two compounds in the host included in the emission layer have different highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels and form an exciplex, and

a difference between a HOMO energy level and a LUMO energy level of the exciplex (ΔEexciplex) is greater than a difference between a HOMO energy level and a LUMO energy level of the dopant (ΔEdopant).

In one embodiment, the second compound may have a smaller electron transport capability compared to the first compound.

In one embodiment, the first compound and the second compound may form an exciplex.

In one embodiment, a HOMO energy level (eV) of an exciplex (HOMOexciplex) may be identical to a HOMO energy level (eV) of the first compound or a HOMO energy level (eV) of the second compound, whichever has a smaller absolute value, and a LUMO energy level (eV) of an exciplex (LUMOexciplex) may be identical to a LUMO energy level (eV) of the first compound or a LUMO energy level (eV) of the second compound, whichever has a greater absolute value.

In one embodiment, a difference between a HOMO energy level of the first compound and a HOMO energy level of the second compound may be about 0.1 eV or more, and a difference between a LUMO energy level of the first compound and a LUMO energy level of the second compound may be about 0.1 eV or more.

In one embodiment, i) both the first compound and the second compound may include an electron transport moiety, ii) neither of the first compound and the second compound may include an electron transport moiety, or iii) the first compound may include an electron transport moiety and the second compound may not include an electron transport moiety.

In one embodiment, i) both the first compound and the second compound may include an electron transport moiety, ii) neither of the first compound and the second compound may include an electron transport moiety, or iii) the first compound may include an electron transport moiety and the second compound may not include an electron transport moiety, and in all cases, the first compound and the second compound may form exciplex.

In one embodiment, the electron transport moiety may be a cyano group, a fluoro group, a π-electron-deficient nitrogen-containing cyclic group, or any combination thereof.

In one embodiment, the first compound may be an electron transport host, and the second compound may be a hole transport compound.

In one embodiment, the first compound and the second compound may each have a higher triplet energy level (T1) than the dopant.

In one embodiment, a weight ratio of the first compound to the second compound may be about 90:10 to about 10:90.

In one embodiment, the host may further include a third compound; the first compound, the second compound, the third compound, and the dopant may be different from each other, two compounds in the host included in the emission layer may have different HOMO and LUMO energy levels and may form an exciplex, and a difference between a HOMO energy level and a LUMO energy level of the exciplex (ΔEexciplex) may be greater than a difference between a HOMO energy level and a LUMO energy level of the dopant (ΔEdopant).

In one embodiment, the third compound may be an electron transport host, a hole transport host, or a bipolar host.

In one embodiment, a weight ratio of the first compound and the second compound to the third compound may be about 1:99 to about 99:1.

In one embodiment, the emission layer may further include two or more hosts for a total of N hosts, wherein N may be an integer of 4 or more; the two or more hosts, the first compound, the second compound, and the dopant may be different from each other; two compounds selected from the N hosts included in the emission layer may have different HOMO and LUMO energy levels and may form an exciplex, and a difference between a HOMO energy level and a LUMO energy level of the exciplex (ΔEexciplex) may be greater than a difference between a HOMO energy level and a LUMO energy level of the dopant (ΔEdopant).

In one embodiment, the exciplex may have an energy band gap (ΔEexciplex) of about 2.5 eV to about 3.5 eV.

In one embodiment, the dopant in the emission layer may be a phosphorescent dopant or a fluorescent dopant.

In one embodiment, the organic layer may further include a hole transport region between the first electrode and the emission layer and an electron transport region between the emission layer and the second electrode; the hole transport region may include at least one selected from a hole injection layer, a hole transport layer, an emission auxiliary layer, and an electron blocking layer; and 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.

In one embodiment, the hole transport region may include an arylamine compound.

In one embodiment, the electron transport region may include a π-electron-deficient nitrogen-containing cyclic containing compound.

One or more example embodiments of the present disclosure provide an organic light-emitting device including:

a first pixel electrode, a second pixel electrode, and a third pixel electrode respectively located in a first emission area, a second emission area, and a third emission area,

a counter electrode facing the first pixel electrode, the second pixel electrode, and the third pixel electrode, and

an organic layer located between the first pixel electrode, the second pixel electrode, and the third pixel electrode and the counter electrode and including an emission layer,

wherein the emission layer includes:

a first emission layer corresponding to the first emission area and emitting first-color light,

a second emission layer corresponding to the second emission area and emitting second-color light, and

a third emission layer corresponding to the third emission area and emitting third-color light,

wherein a maximum emission wavelength of the first-color light and a maximum emission wavelength of the second-color light are each greater than a maximum emission wavelength of the third-color light,

at least two emission layers selected from the first emission layer, the second emission layer, and the third emission layer include a host including a first compound and a second compound and a dopant,

the first compound, the second compound, and the dopant are different from one another,

two compounds in the host included in the emission layer have different HOMO and LUMO energy levels and form an exciplex, and

a difference between a HOMO energy level and a LUMO energy level of the exciplex (ΔEexciplex) is greater than a difference between a HOMO energy level and a LUMO energy level of the dopant (ΔEdopant).

In one embodiment, at least one emission layer selected from the first emission layer, the second emission layer, and the third emission layer may further include a third compound that is different from the first compound and the second compound.

One or more example embodiments of the present disclosure provide an apparatus including: a thin-film transistor including a source electrode, a drain electrode, and an activation layer; and the organic light-emitting device, wherein the first electrode or a pixel electrode of the organic light-emitting device is electrically connected with one selected from the source electrode and the drain electrode of the thin-film transistor.

DETAILED DESCRIPTION

As the present disclosure can be subject to various transformations and can have various examples, selected examples will be illustrated in the drawings and described in detail in the detailed description. Effects and features of the present disclosure, and methods of achieving the same will be clarified by referring to the detailed Examples with reference to the drawings. However, the present disclosure is not limited to the examples disclosed below, and may be implemented in various forms.

As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, the use of “may” when describing embodiments of the present disclosure refers to “one or more embodiments of the present disclosure”.

It will be further understood that the terms “includes,” “including,” “comprises,” and/or “comprising” when used herein specify the presence of stated features or components, but do not preclude the presence or addition of one or more other features or components.

It will be understood that when a layer, region, or component is referred to as being “on” or “onto” another layer, region, or component, it may be directly or indirectly formed on the other layer, region, or component. That is, for example, intervening layers, regions, or components may be present.

Sizes of elements in the drawings may be exaggerated for convenience of explanation. For example, since sizes and thicknesses of components in the drawings are arbitrarily illustrated for convenience of explanation, the following embodiments of the present disclosure are not limited thereto.

The term “an organic layer” as used herein may refer to a single layer and/or a plurality of layers located between the first electrode and the second electrode of an organic light-emitting device. Materials included in the “organic layer” are not limited to being an organic material.

The expression “(an organic layer) includes a compound represented by Formula 1” as used herein may include a case in which “(an organic layer) includes one compound of Formula 1” as well as a case in which “(an organic layer) includes two or more different compounds of Formula 1”.

FIG.1is a schematic cross-sectional view of an organic light-emitting device10according to an embodiment of the present disclosure. The organic light-emitting device10includes: a first electrode110; a second electrode190facing the first electrode110; and an organic layer150located between the first electrode110and the second electrode190and including an emission layer.

Hereinafter, a structure of the organic light-emitting device10according to an embodiment and a method of manufacturing the organic light-emitting device10will be described in connection withFIG.1.

First Electrode110

InFIG.1, a substrate may be additionally disposed under the first electrode110and/or above the second electrode190. The substrate may be a glass substrate and/or a plastic substrate, each having excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and/or water resistance.

The first electrode110may be formed by depositing and/or sputtering a material for forming the first electrode110on the substrate. When the first electrode110is an anode, the material for forming the first electrode110may 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. When the first electrode110is a transmissive electrode, the material for forming the first electrode110may be selected from indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO2), zinc oxide (ZnO), and any combination thereof, but embodiments of the present disclosure are not limited thereto.

The organic layer150is located on the first electrode110. The organic layer150includes an emission layer.

The emission layer may include a host and a dopant, the host may include a first compound and a second compound (e.g., the emission layer may include a first host compound and a second host compound), and the first compound, the second compound, and the dopant may be different from one another. Here, the term “different from” indicates that the compounds are not the same, and may have different structures, compositions, and properties.

In one embodiment, the second compound may be a host having a smaller electron transport capability than the first compound.

Two different host compounds (e.g., molecules) included in the emission layer may form an exciplex, and the energy level difference between the highest occupied molecular orbital (HOMO) energy level and the lowest unoccupied molecular orbital (LUMO) energy level (e.g., the HOMO-LUMO gap or energy band gap) of the exciplex (ΔEexciplex) may be greater than the energy level difference between the HOMO energy level and the LUMO energy level (e.g., the HOMO-LUMO gap) of the dopant (ΔEdopant).

The HOMO energy level (eV) and the LUMO energy level (eV) of the host, the HOMO energy level (eV) and the LUMO energy level (eV) of the exciplex, and the HOMO energy level (eV) and the LUMO energy level (eV) of the dopant may each be measured by cyclic voltammetry (CV).

In one embodiment, the first compound and the second compound may form an exciplex. In this case, the HOMO energy level (eV) of the exciplex (HOMOexciplex) may be identical to the HOMO energy level (eV) of the first compound or the HOMO energy level (eV) of the second compound, whichever has a smaller (lower) absolute value. For example, the HOMO energy level of the exciplex may be identical to the shallower value among the HOMO energy level of the first compound and the HOMO energy level of the second compound.

In one or more embodiments, the LUMO energy level (eV) of the exciplex (LUMOexciplex) may be identical to the LUMO energy level (eV) of the first compound or the LUMO energy level (eV) of the second compound, whichever has a greater (higher) absolute value. For example, the LUMO energy level of the exciplex may be identical to the deeper value among the LUMO energy level of the first compound and the LUMO energy level of the second compound.

FIG.2is an energy diagram of a first compound, a second compound, an exciplex, and a dopant, according to an embodiment.

Referring toFIG.2, for example, when the first compound and the second compound form an exciplex, the HOMO energy level of the exciplex is identical to the HOMO energy level of the second compound, which has a smaller absolute value compared to the HOMO energy level of the first compound; and the LUMO energy level of the exciplex is identical to a LUMO energy level of the first compound, which has a greater absolute value compared to the LUMO energy level of the second compound.

Accordingly, in the example ofFIG.2, a difference between the HOMO energy level and the LUMO energy level (e.g., the HOMO-LUMO gap) of the exciplex (ΔEexciplex) formed by the first compound and the second compound may be the same as the difference between the HOMO energy level of the second compound and the LUMO energy level of the first compound.

An energy band gap of the dopant (ΔEdopant) is smaller than an energy band gap of the exciplex (ΔEexciplex)FIG.2illustrates, for ease of understanding, that the LUMO energy level of the dopant is smaller than the LUMO energy level of the exciplex, and the HOMO energy level of the dopant is greater than the HOMO energy level of the exciplex, (e.g., so that the HOMO-LUMO gap of the dopant is entirely contained within the HOMO-LUMO gap of the exciplex). However, the HOMO and LUMO energy levels of the dopant are not limited thereto, and may each be independently selected as long as the values satisfy ΔEexciplex>ΔEdopant.

When the emission layer exciplex and the dopant satisfy the condition that ΔEexciplexis greater than ΔEdopant, an exciton formed in the exciplex may be efficiently transferred to the dopant. In addition, compared to an emission layer including a single host, when an emission layer includes at least two hosts, energy may be efficiently transferred from the hosts to the dopant. Thus, the organic light-emitting device may have high efficiency and/or long lifespan.

When the emission layer includes two or more hosts, compared to a case of the emission layer including one host, a hole-electron charge balance in the emission layer may be improved. When the first compound has greater electron mobility than the second compound, the first compound may be an electron transport host having relatively strong electron transport characteristics in the emission layer, and the second compound may be a hole transport host having relatively strong hole transport characteristics in the emission layer, but embodiments of the present disclosure are not limited thereto.

When the emission layer includes at least two hosts, holes provided from the first electrode110may flow to the emission layer via the HOMO of the hole transport host, and electrons provided from the second electrode190may flow to the emission layer via the LUMO of the electron transport host.

Even though the hole transport host including the holes and the electron transport host including the electrons may contact each other in the emission layer, because the holes and the electrons exist in (e.g., are concentrated on) different compounds, excitons may not be easily formed. In this case, when the electron transport host transfers electrons to the hole transport host, excitons may be formed in the hole transport host, or when the hole transport host transfers holes to the electron transport host, excitons may be formed in the electron transport host. In one or more embodiments, when the electron transport host and the hole transport host respectively transfer electrons and holes to the dopant, excitons may be formed in the dopant. As such, it is only when carriers are transferred over the energy barrier therebetween that excitons are formed to thereby emit light. Thus, driving voltage of an organic light-emitting device may be increased.

In contrast, in the organic light-emitting device according to an embodiment, two host compounds in the emission layer, for example, the first compound and the second compound, may have different HOMO and LUMO energy levels and may form an exciplex, and thus excitons may be formed without transferring holes or electrons over an energy barrier therebetween (e.g., the energy barrier for transfer of holes and/or electrons may be reduced, and in some embodiments, substantially zero).

As such, when the HOMO and LUMO energy levels of compounds or materials in the emission layer are aligned to induce efficient carrier injection, injection of holes and electrons may be improved, and excitons may be formed in the emission layer without an energy barrier due to the exciplex formed by the first compound and the second compound, such that the organic light-emitting device10may have low driving voltage and/or high efficiency.

The first compound and the second compound, which are host compounds in the emission layer, are not limited to being particular compounds as long as the exciplex formed in the emission layer can satisfy ΔEexciplex>ΔEdopant.

In one or more embodiments, when the first compound and the second compound in the emission layer form an exciplex, in order to efficiently form an exciplex, the difference between the HOMO energy level of the first compound and the HOMO energy level of the second compound may be, for example, about 0.1 eV or more, and the difference between the LUMO energy level of the first compound and the LUMO energy level of the second compound may be, for example, about 0.1 eV or more, but embodiments of the present disclosure are not limited thereto.

In one embodiment, the HOMO energy level of the second compound may be at least about 0.1 eV higher than the HOMO energy level of the first compound, and the LUMO energy level of the second compound may be at least about 0.1 eV higher than the LUMO energy level of the first compound, but embodiments of the present disclosure are not limited thereto. A first compound and a second compound satisfying the above-described energy conditions may efficiently form an exciplex.

In respective embodiments, i) both the first compound and the second compound may include an electron transport moiety, ii) neither of the first compound and the second compound may include an electron transport moiety, or iii) the first compound may include an electron transport moiety and the second compound may not include an electron transport moiety, or vice versa, and in each embodiment, the first compound and the second compound may form an exciplex.

In one embodiment, the electron transport moiety may be a cyano group, a fluoro group, a π-electron-deficient nitrogen-containing cyclic group, or any combination thereof.

The term “π-electron-deficient nitrogen-containing cyclic group” as used herein refers to a heterocyclic group having at least one *—N═*′ moiety as a ring-forming moiety.

In one embodiment, the first compound may be an electron transport host, and the second compound may be a hole transport compound.

In one embodiment, the first compound and the second compound may both (each) include an electron transport moiety, the first compound may be an electron transport host, and the second compound may be a hole transport host. In this case, the first compound may be or act as an electron transport host having electron injection and transport characteristics, and the second compound may be or act as a hole transport host having hole injection and transport characteristics, consistent with the relative magnitudes of electron mobility of the first compound and the second compound.

In one embodiment, neither of the first compound and the second compound may include an electron transport moiety, the first compound may be an electron transport host, and the second compound may be a hole transport host. For example, even a host or first compound that does not include an electron transport moiety may be or act as an electron transport host having electron injection and transport characteristics due to the comparative magnitudes of electron mobility of the first compound and the second compound, and the second compound may be or act as a hole transport host having hole injection and transport characteristics.

In one or more embodiments, the first compound may be an electron transport host including an electron transport moiety, and the second compound may be a hole transport host including a hole transport moiety.

The first compound may have high electron transport characteristics and may stably and efficiently transport electrons, thereby lowering the driving voltage, increasing current efficiency, and supporting long lifespan characteristics of a device.

The second compound may have hole transport characteristics and may efficiently transport holes with relative stability, thereby contributing to improvement of device characteristics.

In one embodiment, the first compound may be a bipolar compound including both an electron transport moiety and a hole transport moiety (e.g., simultaneously). The hole transport moiety may include a carbazole, a dibenzofuran, a dibenzothiophene, an amine group, and/or the like.

In one embodiment, both the first compound and the second compound may be bipolar compounds. However, an electron transport capability of the first compound may be greater than that of the second compound.

In one embodiment, an electron mobility of the first compound μ(C1) may be greater than that of the second compound μ(C2).

μ(C1) and μ(C2) may each be evaluated using DFT methods, for example, with the Gaussian program on structures optimized using the B3LYP/6-31G(d,p) functional and basis set.

In one embodiment, the first compound and the second compound may each have a higher triplet energy level (T1) than the dopant.

When the first compound and the second compound each have a triplet energy level (T1) satisfying the above-described condition, excitons recombined in a host or an exciplex may be efficiently transferred to the dopant.

In one embodiment, the first compound and the second compound may each independently be selected from compounds represented by Formulae 1 to 3 and 301.

In Formula 1,

Y1to Y8may each independently be N or C(R14), wherein, when C(R14) is 2 or more, two or more of R14(s) may be identical to or different from each other,

L11to L13may each independently be a substituted or unsubstituted C5-C60carbocyclic group or a substituted or unsubstituted C1-C60heterocyclic group,

a11 to a13 may each independently be an integer from 0 to 5,

two adjacent groups selected from R11to R14, R11a, and R11bmay optionally be linked together via a linking group selected from a single bond, *—O—*′, *—S—*′, *—B(R15)—′, *—N(R15)—*′, *—C(R15)(R16)—*′, *—C(R15)═C(R16)—′, a C5-C30carbocyclic group, and a C1-C30heterocyclic group,

R15and R16may each independently be selected from: hydrogen, a C1-C20alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; and a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, each substituted with at least one selected from deuterium, a C1-C20alkyl group, a phenyl group, a biphenyl group, a terphenyl group, and a naphthyl group,

b11 to b13 may each independently be an integer from 1 to 5, and

n1 and n2 may each independently be an integer from 1 to 4.

In Formula 2,

Y11to Y18may each independently be N or C(R24), wherein, when C(R24) is 2 or more, two or more of R24(s) may be identical to or different from each other,

CY1may be a group represented by Formula 2A, and CY2may be a group represented by Formula 2B,

in Formula 2A, C* and C** may each be a carbon condensed with an X21-containing 5-membered ring,

in Formula 2A, Y19to Y22may each independently be N, C, or C(R25), wherein, when C(R25) is 2 or more, two or more of R25(s) may be identical to or different from each other, and two adjacent among Y19to Y22may each be a carbon condensed with an X22-containing 5-membered ring,

L21to L24may each independently be a substituted or unsubstituted C5-C60carbocyclic group or a substituted or unsubstituted C1-C60heterocyclic group,

a21 to a24 may each independently be an integer from 0 to 5,

two adjacent groups selected from R21to R26, R21a, R21b, R26a, and R26bmay optionally be linked together via a linking group selected from a single bond, *—O—*′, *-5-*′*—B(R27)—′, *—N(R27)—*′, *—C(R27)(R28)—*′, —C(R27)═C(R28)—′, a C5-C30carbocyclic group, and a C1-C30heterocyclic group,

R27and R28may each independently be selected from: hydrogen, a C1-C20alkyl group, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group; and a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a fluorenyl group, a carbazolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, each substituted with at least one selected from deuterium, a C1-C20alkyl group, a phenyl group, a biphenyl group, a terphenyl group, and a naphthyl group,

b21 to b23 and b26 may each independently be an integer from 1 to 5, and

n21 and n22 may each independently be an integer from 1 to 4.

In Formula 3,

a31 may be an integer from 0 to 5,

b31 and b32 may each independently be an integer from 1 to 5, and

n31 may be an integer from 1 to 3.

wherein Q31to Q33may each independently be the same as described above.

In one embodiment, the compound represented by Formula 2 may be represented by any one of Formulae 2-1 to 2-6:

In one embodiment, the compound represented by Formula 3 may be represented by Formula 3-1:

In Formula 3-1, L31, L32, a31, a32, R31, R32, b31, and b32 may each independently be the same as described in the present specification,

L32and R33may each independently be the same as described in connection with L31and R31, respectively,

a32 may be an integer from 0 to 5, and

b33 may be an integer from 1 to 5.
[Ar301]xb11-[(L301)xb1-R301]xb21.  Formula 301

In Formula 301,

Ar301may be selected from a substituted or unsubstituted C5-C60carbocyclic group and a substituted or unsubstituted C1-C60heterocyclic group,

xb11 may be an integer from 1 to 3,

xb1 may be an integer from 0 to 5,

xb21 may be an integer from 1 to 5,

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

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

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

In Formulae 301-1 and 301-2

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

L301, xb1, R301, and Q31to Q33may each independently be the same as described above,

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, L301to L304in Formulae 301, 301-1, and 301-2 may each independently be selected from:

wherein Q31to Q33may each independently be the same as described above.

In one embodiment, R301to R304in Formulae 301, 301-1, and 301-2 may each independently be selected from:

wherein Q31to Q33may each independently be the same as described above.

In one or more embodiments, the first compound and the second compound may each independently be selected from Compounds C1 to C12 and H1 to H55, but embodiments of the present disclosure are not limited thereto:

In one or more embodiments, the first compound and the second compound may each independently be selected from Compounds C1 to C12 and H1 to H55, but the first compound and the second compound are different from each other. In addition, an electron transport capability of the second compound may be smaller than that of the first compound.

When the host includes the first compound and the second compound, a weight ratio of the first compound to the second compound may be about 90:10 to about 10:90. In one or more embodiments, a weight ratio of the first compound to the second compound may be about 20:80 to about 80:20 or about 30:70 to about 70:30. When a weight ratio of the first compound to the second compound is within the range, charge balance may be maintained in the emission layer, and thus, efficiency and lifespan may be improved.

In one embodiment, the host may further include a third compound, in addition to the first compound and the second compound. The first compound, the second compound, the third compound, and the dopant are different from each other.

When the carrier transport characteristics of the first host compound and/or the second host compound are insufficient, charge balance of the emission layer may be attained by introducing a third compound that is different from the first compound and the second compound. Thus, efficiency and lifespan of an organic light-emitting device may be further improved.

In one or more embodiments, the third compound may be an electron transport host, a hole transport host, or a bipolar host.

Two (e.g., any two) of the host compounds in the emission layer may have different HOMO and LUMO energy levels and form an exciplex, and the difference between the HOMO energy level and the LUMO energy level of the exciplex (ΔEexciplex) may be greater than the difference between the HOMO energy level and the LUMO energy level of the dopant (ΔEdopant).

In respective embodiments, the first compound and the second compound may form an exciplex, the second compound and the third compound may form an exciplex, or the first compound and the third compound may form an exciplex, but embodiments of the present disclosure are not limited thereto.

In one embodiment, the first compound, the second compound, and the third compound may each have a higher triplet energy level (T1) than the dopant.

When the first compound, and the second compound, and the third compound each have a triplet energy level (T1) satisfying the described condition, excitons formed by recombination in any host or an exciplex may be efficiently transferred to a dopant.

In one embodiment, the third compound may have electron transport characteristics or hole transport characteristics.

In one or more embodiments, the first compound may be an electron transport host, and the second compound and the third compound may each be a hole transport host. In one or more embodiments, the first compound and the second compound may each be an electron transport host, and the third compound may be a hole transport host. In one or more embodiments, the first compound and the third compound may each be an electron transport host, and the second compound may be a hole transport host. The third compound may supplement carrier transport characteristics that are relatively insufficient in an emission layer including a composition of the first compound and the second compound.

In one or more embodiments, the third compound may include an electron transport moiety.

In one or more embodiments, the third compound may not include an electron transport moiety.

In one embodiment, the third compound may be selected from compounds represented by Formulae 1 to 3 above.

In one or more embodiments, the third compound may be selected from Compounds C1 to C12 and H1 to H55, but embodiments of the present disclosure are not limited thereto:

In one or more embodiments, the first compound to the third compound may each independently be selected from Compounds C1 to C12 and H1 to H55, but the first compound, the second compound, and the third compound are different from one another. At the same time (e.g., simultaneously), an electron transport capability of the second compound may be smaller than that of the first compound.

When the host includes the first compound, the second compound, and the third compound, a weight ratio of the first compound and the second compound to the third compound may be about 1:99 to about 99:1. In this case, a weight ratio of the first compound to the second compound may be about 10:90 to about 90:10. When theses ranges are satisfied, the electron transporting capacity of the first compound and the hole transport capacity of the second compound may be balanced, such that bipolar characteristics may be realized, and the third compound may supplement the carrier transport characteristics that are relatively insufficient in an emission layer. Thus, the efficiency and/or lifespan of an organic light-emitting device may be improved. In one or more embodiments, a weight ratio of the first compound and the second compound to the third compound may be about 10:90 to about 90:10, about 20:80 to about 80:20, about 30:70 to about 70:30, about 40:60 to about 70:30, or about 50:50 to about 70:30.

In one or more embodiments, the emission layer may further include two or more hosts (e.g., at least four or more host compounds in total), and the two or more hosts, the first compound, the second compound, and the dopant may be different from each other.

In this case, two of the compounds having different HOMO and LUMO energy levels among the N hosts included in the emission layer (where N is an integer of 4 or more) may form an exciplex, and a difference between the HOMO energy level and the LUMO energy level of the exciplex (ΔEexciplex) may be greater than the difference between the HOMO energy level and the LUMO energy level of the dopant (ΔEdopant).

When there are N different hosts included in the emission layer, the emission layer may include a first compound to an Nth compound.

For example, the emission layer of the organic light-emitting device (10) may include one of the following combinations:

i) a first compound, a second compound, and a dopant;

ii) a first compound, a second compound, a third compound, and a dopant; and

iii) a first compound, a second compound, a third compound, . . . , an (N−1)th compound, an Nth compound, and a dopant.

The exciplex may have an energy band gap (ΔEexciplex) of, for example, about 2.5 eV to about 3.5 eV.

When the dopant is a red dopant, the dopant may have an energy band gap (ΔEdopant) of about 1.7 eV to about 3.2 eV. When the dopant is a green dopant, the dopant may have an energy band gap (ΔEdopant) of about 1.9 eV to about 3.2 eV. When the dopant is a blue dopant, the dopant may have an energy band gap (ΔEdopant) of about 2.0 eV to about 3.0 eV.

The dopant may be, for example, a phosphorescent dopant or a fluorescent dopant. The phosphorescent dopant or a fluorescent dopant may each be a red, green, or blue dopant. In one or more embodiments, the phosphorescent dopant may be a red or green phosphorescent dopant, and/or the fluorescent dopant may be a blue fluorescent dopant.

In one or more embodiments, an amount of the dopant in the emission layer may be about 0.01 parts by weight to about 30 parts by weight based on about 100 parts by weight of the host, but embodiments of the present disclosure are not limited thereto.

When the emission layer is patterned into a red emission layer, a green emission layer, or a blue emission layer, according to a subpixel, at least one of the red emission layer, the green emission layer, and the blue emission layer may include the first compound, the second compound, and the dopant, or in some embodiments may include the first compound, the second compound, the third compound, and the dopant.

Hole Transport Region in Organic Layer150

The hole transport region may have: i) a single-layered structure including (e.g., consisting of) a single material, ii) a single-layered structure including (e.g., consisting of) a plurality of different materials, or iii) a multi-layered structure having a plurality of layers including (e.g., consisting of) a plurality of different materials.

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 (e.g., consisting of) 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 constituting layers of each structure are sequentially stacked from the first electrode110in each stated order, but the structure of the hole transport region is not limited thereto.

The hole transport region may include an arylamine compound or a hole transport polymer.

In Formulae 201 and 202,

xa5 may be an integer from 1 to 10, and

In one or more embodiments, in Formula 202, R201and R202may optionally be linked to each other via a single bond, a dimethyl-methylene group, or a diphenyl-methylene group, and R203and R204may optionally be linked to each other 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 embodiment, xa1 to xa4 may each independently be 0, 1, or 2.

wherein Q31to Q33may each independently be the same as described above.

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

In one embodiment, in Formula 202, i) R201and R202may be linked to each other via a single bond, and/or ii) R203and R204may be linked to each other via a single bond.

In one embodiment, 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 201-2, but embodiments of the present disclosure are not limited thereto:

In one or more embodiments, the compound represented by Formula 201 may be represented by Formula 201-2(1), but embodiments of the present disclosure are not limited thereto:

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

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

In one or more embodiments, the compound represented by Formula 202 may be represented by Formula 202-1:

In one or more embodiments, the compound represented by Formula 202 may be represented by Formula 202-1(1):

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

In one or more embodiments, the compound represented by Formula 202 may be represented by Formula 202A-1:

L201to L203, xa1 to xa3, xa5, and R202to R204may each independently be the same as described above,

L205may be selected from a phenylene group, and a fluorenylene group,

X211may be selected from O, S, and N(R211),

X212may be selected from O, S, and N(R212),

R211and R212may each independently be the same as described in connection with R203, and

The hole transport region may include at least one compound selected from Compounds HT1 to HT72, but compounds to be included in the hole transport region are not limited thereto:

A thickness of the hole transport region may be about 100 Å to about 10,000 Å, for example, about 100 Å to about 1,000 Å. When the thickness of the hole transport region is within the range described above, satisfactory hole transportation characteristics may be obtained without a substantial increase in driving voltage.

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

In one embodiment, a LUMO energy level of the p-dopant may be −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.

In one embodiment, the p-dopant may include at least one selected from:

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

a compound represented by Formula 221,

In Formula 221,

Phosphorescent Dopant in Emission Layer

In Formulae 401 and 402,

L401may be selected from ligands represented by Formula 402, and xc1 may be 1, 2, or 3, wherein when xc1 is two or more, two or more of L401(s) may be identical to or different from each other,

L402may be an organic ligand, and xc2 may be an integer from 0 to 4, wherein when xc2 may be two or more, two or more of L402(s) may be identical to or different from each other,

X401to X404may each independently be nitrogen or carbon,

X401and X403may be linked via a single bond or a double bond, and X402and X404may be linked via a single bond or a double bond,

A401and A402may each independently be a C5-C60carbocyclic group or a C1-C60heterocyclic group,

X406may be a single bond, O, or S,

R401and R402may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amidino group, a hydrazino group, a hydrazono group, a substituted or unsubstituted C1-C20alkyl group, a substituted or unsubstituted C1-C20alkoxy 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 C1-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, and a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —Si(Q401)(Q402)(Q403), —N(Q401)(Q402), —B(Q401)(Q402), —C(═O)(Q401), —S(═O)2(Q401), and —P(═O)(Q401)(Q402), and Q401to Q403may each independently be selected from a C1-C10alkyl group, a C1-C10alkoxy group, a C6-C20aryl group, and a C1-C20heteroaryl group,

* and *′ in Formula 402 each indicate a binding site to a M in Formula 401.

In one or more embodiments, in Formula 402, i) X401may be nitrogen and X402may be carbon, or ii) both X401and X402may be nitrogen.

In one or more embodiments, when xc1 in Formula 401 is two or more, two A401(s) in two or more L401(s) may optionally be linked to each other via X407(which is a linking group, and two A402(s) may optionally be linked to each other via X408(which is a linking group) (see Compounds PD1 to PD4 and PD7). X407and X408may each independently be a single bond, *—C(═O)—*′, *—N(Q413)—*′, *—C(Q413)(Q414)—*′ or *—C(Q413)═C(Q414)—*′ (where Q413and Q414may each independently be hydrogen, deuterium, a C1-C20alkyl group, a C1-C20alkoxy group, a phenyl group, a biphenyl group, a terphenyl group, or a naphthyl group), but embodiments of the present disclosure are not limited thereto.

L402in Formula 401 may be a monovalent, divalent, or trivalent organic ligand. For example, L402may be selected from a halogen, a diketone (for example, acetylacetonate), a carboxylic acid (for example, picolinate), —C(═O), an isonitrile, —CN, and a phosphorus-based ligand (for example, phosphine or phosphite), but embodiments of the present disclosure are not limited thereto.

In one or more embodiments, the phosphorescent dopant may be selected from, for example, Compounds PD1 to PD25, but embodiments of the present disclosure are not limited thereto:

Fluorescent Dopant in Emission Layer

The fluorescent dopant may include an arylamine compound or a styrylamine compound.

The fluorescent dopant may include a compound represented by Formula 501:

In Formula 501,

xd1 to xd3 may each independently be an integer from 0 to 3,

xd4 may be an integer from 1 to 6.

In one embodiment, Ar501in Formula 501 may be selected from:

In one embodiment, L501to L503in Formula 501 may each independently be selected from:

In one or more embodiments, R501and R502in Formula 501 may each independently be selected from:

In one or more embodiments, xd4 in Formula 501 may be 2, but embodiments of the present disclosure are not limited thereto.

For example, the fluorescent dopant may be selected from Compounds FD1 to FD22:

In one or more embodiments, the fluorescent dopant may be selected from the following compounds, but embodiments of the present disclosure are not limited thereto:

Electron Transport Region in Organic Layer150

The electron transport region may have i) a single-layered structure including (e.g., consisting of) a single material, ii) a single-layered structure including (e.g., consisting of) a plurality of different materials, or iii) a multi-layered structure having a plurality of layers including (e.g., consisting of) a plurality of different materials.

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 the constituting layers of each structure 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, and/or an electron transport layer in the electron transport region) may include a metal-free compound containing at least one π-electron-deficient nitrogen-containing ring.

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

For example, the electron transport region may include a compound represented by Formula 601:
[Ar601]xe11-[(L601)xe1-R601]xe21.  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 the xe11 Ar601(s) and the xe21 R601(s) may include the π-electron-deficient nitrogen-containing ring.

In one embodiment, ring Ar601in Formula 601 may be selected from:

When xe11 in Formula 601 is 2 or more, two or more Ar601(s) may be linked to each other via a single bond.

In one embodiment, Ar601in Formula 601 may be an anthracene group.

In one or more embodiments, the 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), X616may be N or C(R616), and at least one of 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, L601and L611to L613in Formulae 601 and 601-1 may each independently be selected from:

In one or more embodiments, R601and R611to R613in Formulae 601 and 601-1 may each independently be selected from:

wherein Q601and Q602may each independently be the same as described above.

The electron transport region may include at least one compound selected from Compounds ET1 to ET96, but compounds to be included in the electron transport region are not limited thereto:

The thicknesses of the buffer layer, the hole blocking layer, and the electron control layer may each independently be 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 the electron control layer are within these ranges, excellent hole blocking characteristics or excellent electron control characteristics may be obtained without a substantial increase in driving voltage.

The metal-containing material may include at least one selected from an alkali metal complex and an alkaline earth-metal complex. A metal ion of the alkali metal complex may be selected from a lithium (Li) ion, a sodium (Na) ion, a potassium (K) ion, a rubidium (Rb) ion, and a cesium (Cs) ion, and a metal ion of the alkaline earth-metal complex may be selected from a beryllium (Be) ion, a magnesium (Mg) ion, a calcium (Ca) ion, a strontium (Sr) ion, and a barium (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 to facilitate electron injection from the second electrode190. The electron injection layer may directly contact the second electrode190.

The electron injection layer may have i) a single-layered structure including (e.g., consisting of) a single material, ii) a single-layered structure including (e.g., consisting of) a plurality of different materials, or iii) a multi-layered structure having a plurality of layers including (e.g., consisting of) a plurality of different materials.

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 combination thereof.

The alkali metal may be selected from Li, Na, K, Rb, and Cs. In one embodiment, the alkali metal may be Li, Na, or Cs. In one embodiment, 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 scandium (Sc), yttrium (Y), cerium (Ce), terbium (Tb), ytterbium (Yb), and gadolinium (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, and/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, and/or K2O), and alkali metal halides (such as LiF, NaF, CsF, KF, LiI, NaI, CsI, and/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), and/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, Sc2O3, Y2O3, Ce2O3, GdF3, and TbF3. In one embodiment, the rare earth metal compound may be selected from YbF3, ScF3, TbF3, YbI3, ScI3, and TbI3, 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 (e.g., 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 combination 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, the alkali metal, the alkaline earth metal, the rare earth metal, the alkali metal compound, the alkaline earth-metal compound, the rare earth metal compound, the alkali metal complex, the alkaline earth-metal complex, the rare earth metal complex, or combination thereof may be homogeneously or non-homogeneously dispersed in a matrix including (e.g., formed of) the organic material.

The second electrode190is located on the organic layer150. 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 a metal, an alloy, an electrically conductive compound, and any combination thereof, each having 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.

The organic light-emitting device10may further include a capping layer positioned in a direction of light emission.

The capping layer may increase the external luminescence efficiency of the device according to the principle of constructive interference.

The capping layer may have a refractive index of about 1.6 or more with respect to a wavelength of about 589 nm.

The capping layer may be an organic capping layer consisting of an organic material, an inorganic capping layer consisting of an inorganic material, or a composite capping layer including an organic material and an inorganic material.

The capping layer may include at least one material selected from carbocyclic compounds, heterocyclic compounds, amine-based compounds, porphyrin derivatives, phthalocyanine derivatives, naphthalocyanine derivatives, alkali metal complexes, and alkaline earth-metal complexes. The carbocyclic compound, the heterocyclic compound, and the amine-based compound may each be optionally substituted with a substituent containing at least one element selected from oxygen (O), nitrogen (N), sulfur (S), selenium (Se), silicon (Si), fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). In one embodiment, the capping layer may include an amine-based compound.

In one embodiment, the capping layer may include a compound represented by Formula 201 or a compound represented by Formula 202.

In one or more embodiments, the capping layer may include a compound selected from Compounds HT28 to HT33 and Compounds CP1 to CP5, but embodiments of the present disclosure are not limited thereto:

Hereinbefore, the organic light-emitting device has been described with reference toFIG.1, but embodiments of the present disclosure are not limited thereto.

The layers constituting the hole transport region, the emission layer, and the layers constituting the electron transport region may each be formed in a set or predetermined region 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 (LITI).

When the layers constituting the hole transport region, the emission layer, and the layers constituting the electron transport region are formed by spin coating, the spin coating may be performed at a coating speed of about 2,000 rpm to about 5,000 rpm and at a heat treatment temperature of about 80° C. to 200° C., depending on the material to be included and the structure of the layer to be formed.

FIG.3is a schematic cross-sectional view of an organic light-emitting device20according to an embodiment.

Although a substrate201is described, other substrates or variations thereof may be used. In some embodiments, for example, a thin-film transistor including a source electrode, a drain electrode, an activation layer, a buffer layer, and an organic insulation layer may be further located between the substrate201and first, second, and third pixel electrodes211,212, and213.

The organic light-emitting device20ofFIG.3includes a first emission area, a second emission area, and a third emission area.

The organic light-emitting device20includes the first pixel electrode211, the second pixel electrode212, and the third pixel electrode213, respectively located in the first emission area, the second emission area, and the third emission area.

The first pixel electrode211, the second pixel electrode212, and the third pixel electrode213are the same as described in connection with the first electrode110in the present specification.

The first pixel electrode211, the second pixel electrode212, and the third pixel electrode213may each be electrically connected with any one of the source electrode and the drain electrode of the thin-film transistor.

The organic light-emitting device20includes a counter electrode290facing the first pixel electrode211, the second pixel electrode212, and the third pixel electrode213.

An organic layer is located between the counter electrode290and the first pixel electrode211, the second pixel electrode212, and the third pixel electrode213.

The organic layer includes a hole injection layer220, a hole transport layer230, emission layers251,252, and253, an electron transport layer260, and an electron injection layer270. Although not shown inFIG.3, an emission auxiliary layer may be located between the hole transport layer230and the first emission layer251, the hole transport layer230and the second emission layer252, and/or the hole transport layer230and the third emission layer253.

A pixel-defining film205is formed on edge portions of the first pixel electrode211, the second pixel electrode212, and the third pixel electrode213. The pixel-defining film205defines each pixel area and may include or be formed of any suitable organic insulation material (for example, silicon-based materials), inorganic insulation materials, or organic/inorganic composite insulation materials.

The hole injection layer220and the hole transport layer230may be sequentially formed as common layers on the first pixel electrode211, the second pixel electrode212, and the third pixel electrode213.

The hole injection layer220and the hole transport layer230may be the same as described in connection with the organic light-emitting device10in the present specification.

The first emission layer251may be located corresponding to the first emission area to emit first-color light, the second emission layer252may be located corresponding to the second emission area to emit second-color light, and the third emission layer253may be located corresponding to the third emission area to emit third-color light, each being formed on the hole transport layer230.

The electron transport layer260, the electron injection layer270, and the counter electrode290may be sequentially formed as common layers with respect to the first emission area, the second emission area, and the third emission area.

The electron transport layer260and the electron injection layer270may be the same as described in connection with the organic light-emitting device10in the present specification. The counter electrode290may be the same as described in connection with the second electrode190in the present specification.

A capping layer300is located on the counter electrode290. The capping layer300may include or be formed of the organic material and/or the inorganic material described above. In one or more embodiments, the capping layer300may include compounds selected from Compounds HT28 to HT33 and Compounds CP1 to CP5, but embodiments of the present disclosure are not limited thereto.

The capping layer300may aid in efficient emission of light generated from the organic light-emitting device20, and may protect the organic light-emitting device20.

A maximum emission wavelength of the first-color light and a maximum emission wavelength of the second-color light may each be greater than a maximum emission wavelength of the third-color light.

The first color light may be red light, the second color light may be green light, and the third color light may be blue light, but embodiments of the present disclosure are not limited thereto. Accordingly, the organic light-emitting device20may emit full color. However, the first-color light, the second-color light, and the third-color light are not limited to the above, provided that the mixed color light can be white light.

In one or more embodiments, a maximum emission wavelength of the first-color light may be about 620 nm to about 750 nm, a maximum emission wavelength of the second-color light may be about 495 nm to about 570 nm, and a maximum emission wavelength of the third-color light may be about 430 nm to about 495 nm, but embodiments of the present disclosure are not limited thereto.

At least two of the emission layers among the first emission layer251, the second emission layer252, and the third emission layer253may include a host including a first compound and a second compound and a dopant, wherein the first compound, the second compound, and the dopant are different from one another.

Two host compounds in the emission layer having different HOMO and LUMO energy levels form an exciplex, and a difference between a HOMO energy level and a LUMO energy level of the exciplex (ΔEexciplex) may be greater than a difference between a HOMO energy level and a LUMO energy level of the dopant (ΔEdopant).

The first compound, the second compound, and the dopant may each be the same as described in connection with the organic light-emitting device10.

In one embodiment, the second compound may be a host having a smaller electron transport capability than the first compound.

In one embodiment, two emission layers selected from the first emission layer251, the second emission layer252, and the third emission layer253may each include two hosts (i.e., the first compound and the second compound) and a dopant, and in some embodiments, the first emission layer251, the second emission layer252, and the third emission layer253may each include two hosts (the first compound and the second compound) and a dopant.

In one embodiment, at least one emission layer selected from the first emission layer251, the second emission layer252, and the third emission layer253may further include a third compound that is different from the first compound and the second compound.

In one embodiment, at least one emission layer selected from the first emission layer251, the second emission layer252, and the third emission layer253may further include two or more hosts, each being different from the first compound and the second compound.

When there are N different hosts included in the emission layer, the emission layer may include a first compound to an Nth compound.

For example, at least one of the first emission layer251, the second emission layer252, and the third emission layer253of the organic light-emitting device20may include one of the following combinations:

i) a first compound, a second compound, and a dopant;

ii) a first compound, a second compound, a third compound, and a dopant; and

iii) a first compound, a second compound, a third compound, . . . , an (N−1)th compound, an Nth compound, and a dopant.

InFIG.3, the organic light-emitting device20including the pixel-defining film205, the hole injection layer220, the hole transport layer230, the electron transport layer260, and the electron injection layer270is illustrated, but various suitable modifications are possible, and for example, at least one of the described layers may be omitted.

Apparatus

The organic light-emitting device may be included in various suitable apparatuses.

One or more example embodiments of the present disclosure provide is an apparatus including the organic light-emitting device.

The apparatus may be, for example, a light-emitting apparatus, an authentication apparatus, or an electronic apparatus, but embodiments of the present disclosure are not limited thereto.

The light-emitting apparatus may be used as any suitable display, light source, and/or the like.

The authentication apparatus may be, for example, a biometric authentication apparatus for authenticating an individual using biometric information of a biometric body (for example, a fingertip, a pupil, and/or the like).

The authentication apparatus may further include, in addition to the organic light-emitting device, a biometric information collector.

The electronic apparatus may be applied to personal computers (for example, a mobile personal computer), mobile phones, digital cameras, electronic organizers, electronic dictionaries, electronic game machines, medical instruments (for example, electronic thermometers, sphygmomanometers, blood glucose meters, pulse measurement devices, pulse wave measurement devices, electrocardiogram (ECG) displays, ultrasonic diagnostic devices, or endoscope displays), fish finders, various measuring instruments, meters (for example, meters for a vehicle, an aircraft, and a vessel), projectors, and/or the like, but embodiments of the present disclosure are not limited thereto.

In one embodiment, the apparatus may further include, in addition to the organic light-emitting device, a thin-film transistor. Here, the thin-film transistor includes a source electrode, an activation layer, and a drain electrode, and the first electrode or a pixel electrode of the organic light-emitting device may be in electrical contact (e.g., electrically connected) with one of the source electrode and the drain electrode of the thin-film transistor.

General Definition of Substituents

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, only carbon atoms as ring-forming atoms, and non-aromaticity in its entire molecular structure. Non-limiting examples of the monovalent non-aromatic condensed polycyclic group include an adamantyl group. The term “divalent non-aromatic condensed polycyclic group” as used herein refers to a divalent group having substantially the same structure as the monovalent non-aromatic condensed polycyclic group.

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 non-aromaticity in its entire molecular structure. Non-limiting examples of the monovalent non-aromatic condensed heteropolycyclic group include an azaadamantyl group. The term “divalent non-aromatic condensed heteropolycyclic group” as used herein refers to a divalent group having the same structure as the monovalent non-aromatic condensed heteropolycyclic group.

The term “C5-C60carbocyclic group” as used herein refers to a monocyclic or polycyclic group that includes only carbon as a ring-forming atom, and consists of 5 to 60 carbon atoms. The C5-C60carbocyclic group may be an aromatic carbocyclic group or a non-aromatic carbocyclic group. The C5-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 C5-C60carbocyclic group, the C5-C60carbocyclic group may be a trivalent group or a quadrivalent group.

The term “C1-C60heterocyclic group” as used herein refers to a group having substantially the same structure as the C5-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 1 to 60).

The term “terphenyl group” as used herein refers to “a phenyl group substituted with a biphenyl group”. For example, a “terphenyl group” is “a substituted phenyl group” having, as a substituent, “a C6-C60aryl group substituted with a C6-C60aryl group”.

Hereinafter, a light-emitting device according to embodiments will be described in more detail with reference to Examples.

EXAMPLES

Evaluation Example 1: Evaluation of HOMO and LUMO Energy Levels

The HOMO and LUMO energy levels of Compounds C1 to C12 used in Examples 1-1 to 1-11, 2-1 to 2-10, and 3-1 to 3-14, Compounds HA1 to HA6 used in Comparative Examples 1-1 to 1-4, 2-1 to 2-3, and 3-1 to 3-4, and Compounds PRD, PGD, and FBD, were measured by cyclic voltammetry, and results thereof are shown in Table 1.

Red Device Preparation Example

A 15 Ω/cm2(1,200 Å) ITO glass substrate (anode) available from Corning was cut to a size of 50 mm×50 mm×0.5 mm, sonicated with acetone, isopropyl alcohol, and pure water each for 15 minutes, and then cleaned by irradiation of ultraviolet rays and exposure of ozone thereto for 30 minutes. Then, the ITO glass substrate was provided to a vacuum deposition apparatus.

m-MTDATA was deposited on the ITO glass substrate to form a hole injection layer having a thickness of 110 nm, and NPB was deposited on the hole injection layer to form a hole transport layer having a thickness of 10 nm, thereby completing formation of a hole transport region.

A host and a dopant were co-deposited on the hole transport region so that a concentration of the dopant in the host was 2 wt %, thereby forming an emission layer having a thickness of 45 nm. As hosts, a first compound (C1) and a second compound (C2) were co-deposited at a deposition speed of 25 nm/min and 20 nm/min, respectively, and as a dopant, Compound PRD was used.

BAlq was deposited on the emission layer to form a hole blocking layer having a thickness of 10 nm, and subsequently, Alq3and LiQ were co-deposited thereon to form an electron transport layer having a thickness of 30 nm.

LiF was deposited on the electron transport layer to form an electron injection layer having a thickness of 1.3 nm, and subsequently Al was deposited thereon to form a cathode having a thickness of 200 nm. HT28 was deposited on the cathode to form a capping layer having a thickness of 60 nm, thereby completing the manufacture of an organic light-emitting device.

Examples 1-2 to 1-11 and Comparative Examples 1-1 to 1-4

Additional organic light-emitting devices were manufactured in substantially the same manner as in Example 1-1, except that, in forming an emission layer, the host and dopant compounds shown in Table 2 were used.

Evaluation Example 2: Red Device Evaluation Example

For each of the organic light-emitting devices manufactured according to Examples 1-1 to 1-11 and Comparative Examples 1-1 to 1-4, a driving voltage (V) at a current density of 10 mA/cm2, efficiency (cd/A), and lifespan (LT97) were measured, and the results are shown in Table 2. The driving voltage and the current density of the organic light-emitting devices were measured using a source meter (manufactured by Keithley Instrument Inc., 2400 series).

From Table 2, it is confirmed that the organic light-emitting devices manufactured according to Examples 1-1 to 1-11 have low driving voltages, high efficiencies, and long lifespans, compared to the organic light-emitting device manufactured according to Comparative Examples 1-1 to 1-4.

Green Device Preparation Example

Examples 2-1 to 2-10 and Comparative Examples 2-1 to 2-3

Additional organic light-emitting devices were manufactured in substantially the same manner as in Example 1-1, except that, in forming an emission layer, the host and dopant compounds shown in Table 3 were used.

Evaluation Example 3: Green Device Evaluation Example

For each of the organic light-emitting devices manufactured according to Examples 2-1 to 2-10 and Comparative Examples 2-1 to 2-3, a driving voltage (V) at a current density of 10 mA/cm2, efficiency (cd/A), and lifespan (LT97) were measured, and the results are shown in Table 3. The driving voltage and the current density of the organic light-emitting devices were measured using a source meter (manufactured by Keithley Instrument Inc., 2400 series).

From Table 3, it is confirmed that the organic light-emitting devices manufactured according to Examples 2-1 to 2-10 have low driving voltage, high efficiency, and long lifespan, compared to the organic light-emitting device manufactured according to Comparative Examples 2-1 to 2-3.

Blue Device Preparation Example

Examples 3-1 to 3-4 and Comparative Examples 3-1 to 3-4

Additional organic light-emitting devices were manufactured in substantially the same manner as in Example 1-1, except that, in forming an emission layer, the host and dopant compounds shown in Table 4 were used.

Evaluation Example 4: Blue Device Evaluation Example

For each of the organic light-emitting devices manufactured according to Examples 3-1 to 3-4 and Comparative Examples 3-1 to 3-4, a driving voltage (V) at a current density of 10 mA/cm2, efficiency (cd/A), and lifespan (LT97) were measured, and the results are shown in Table 4. The driving voltage and the current density of the organic light-emitting devices were measured using a source meter (manufactured by Keithley Instrument Inc., 2400 series).

From Table 4, it is confirmed that the organic light-emitting devices manufactured according to Examples 3-1 to 3-4 have low driving voltage, high efficiency, and long lifespan, compared to the organic light-emitting devices manufactured according to Comparative Examples 3-1 to 3-4.

The organic light-emitting device according to embodiments of the present disclosure may have low driving voltage, high efficiency, and long lifespan.