Patent Application
20240284697
This application claims priority to Korean Patent Application No. 10-2023-0014402, filed on Feb. 2, 2023, in the Korean Intellectual Property Office, and all the benefits accruing therefrom under 35 U.S.C. § 119, the disclosure of which is herein incorporated by reference in its entirety.
The disclosure relates to a light-emitting device and an electronic apparatus including the same.
Organic light-emitting devices are self-emissive devices, which have improved characteristics in terms of viewing angles, response time, brightness, driving voltage, and response speed, and produce full-color images. An organic light-emitting device includes an anode, a cathode, and an interlayer arranged between the anode and the cathode and including a first emission layer and a second emission layer. A hole transport region may be arranged between the anode and the first emission layer, and an electron transport region may be arranged between the second emission layer and the cathode. Holes provided from the anode may move toward the emission layer(s) through the hole transport region, and electrons provided from the cathode may move toward the emission layer(s) through the electron transport region. The holes and the electrons recombine in the emission layer(s) to produce excitons. The excitons may transition from an excited state to a ground state resulting in light emission from the device.
Provided are a light-emitting device including a first emission layer and a second emission layer, and an electronic apparatus including the light-emitting device.
Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments of the disclosure.
According to an aspect of the disclosure, a light-emitting device includes an anode, a cathode facing the anode, a first emission layer arranged on the anode and including a first phosphorescent emitter, and a second emission layer arranged on the first emission layer and including a first fluorescent emitter and a second phosphorescent emitter, wherein a decay time (Tdecay(1)) of the first emission layer is shorter than a decay time (Tdecay(2)) of the second emission layer.
According to another aspect of the disclosure, an electronic apparatus includes the light-emitting device.
The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with FIGURE which is a schematic cross-sectional view of a light-emitting device according to an embodiment.
Reference will now be made in detail to embodiments, an example of which is illustrated in the accompanying FIGURE. The present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below.
As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms, including “at least one,” unless the content clearly indicates otherwise. “At least one” is not to be construed as limiting “a” or “an.” “Or” means “and/or.” As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.
It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.
It will be understood that, although the terms “first,” “second,” “third” etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, “a first element,” “component,” “region,” “layer” or “section” discussed below could be termed a second element, component, region, layer or section without departing from the teachings herein.
“About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” can mean within one or more standard deviations, or within +10% or +5% of the stated value.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
A light-emitting device includes: an anode; a cathode facing the anode; a first emission layer arranged on the anode and including a first phosphorescent emitter; and a second emission layer arranged on the first emission layer and including a first fluorescent emitter and a second phosphorescent emitter, wherein a decay time (Tdecay(1)) of the first emission layer may be shorter than a decay time (Tdecay(2)) of the second emission layer.
In the light-emitting device according to an embodiment, a triplet excited state (T1) of the first phosphorescent emitter may be greater than or equal to a singlet excited state (S1) of the first fluorescent emitter. In addition, in the light-emitting device according to an embodiment, a difference between a triplet excited state (T1) of the first fluorescent emitter and a singlet excited state (S1) of the first fluorescent emitter may be less than 0.3 eV. Accordingly, the decay time Tdecay(2) of the second emission layer may be significantly longer in time than the decay time Tdecay(1) of the first emission layer.
In the light-emitting device according to an embodiment, the first emission layer and the second emission layer may each independently include at least one group selected from a first host and a second host.
The light-emitting device according to an embodiment may satisfy any one of Conditions i) to v):
In the light-emitting device according to an embodiment, a weight of a host included in the first emission layer may be greater than a weight of a first phosphorescent emitter included in the first emission layer. For example, the weight of the first phosphorescent emitter may be less than or equal to 20 parts by weight based on 100 parts by weight (total weight) of the first emission layer.
In the light-emitting device according to an embodiment, a weight of a host included in the second emission layer may be greater than the sum weight of the first fluorescent emitter included in the second emission layer and a weight of the second phosphorescent emitter included in the second emission layer. For example, the sum weight of the first fluorescent emitter and the weight of the second phosphorescent emitter may be less than or equal to 40 parts by weight based on 100 parts by weight (total weight) of the second emission layer.
In the light-emitting device according to an embodiment, the first host may be a hole-transporting host, and the second host may be an electron-transporting host.
In the light-emitting device according to an embodiment, the first host may include at least one carbazole moiety, and the second host may include at least one azine moiety.
The first host may include a compound represented by Formula 1:
For example, ring CY11 to ring CY14 may each independently be a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a thiophene group, a furan group, an indole group, a benzoborole group, a benzophosphole group, an indene group, a benzosilole group, a benzogermole group, a benzothiophene group, a benzoselenophene group, a benzofuran group, a carbazole group, a dibenzoborole group, a dibenzophosphole group, a fluorene group, a dibenzosilole group, a dibenzogermole group, a dibenzothiophene group, a dibenzoselenophene group, a dibenzofuran group, a dibenzothiophene 5-oxide group, a 9H-fluorene-9-one group, a dibenzothiophene 5,5-dioxide group, an azaindole group, an azabenzoborole group, an azabenzophosphole group, an azaindene group, an azabenzosilole group, an azabenzogermole group, an azabenzothiophene group, an azabenzoselenophene group, an azabenzofuran group, an azacarbazole group, an azadibenzoborole group, an azadibenzophosphole group, an azafluorene group, an azadibenzosilole group, an azadibenzogermole group, an azadibenzothiophene group, an azadibenzoselenophene group, an azadibenzofuran group, an azadibenzothiophene 5-oxide group, an aza-9H-fluorene-9-one group, an azadibenzothiophene 5,5-dioxide group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isooxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group, or a 5,6,7,8-tetrahydroquinoline group.
In the light-emitting device according to an embodiment, CY11 to CY14 may each independently be a benzene group or a naphthalene group, each unsubstituted or substituted with deuterium, —F, —Cl, —Br, —I, —CD3, —CD2H, —CDH2, —CF3, —CF2H, —CFH2, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a C1-C60 alkyl group, or a combination thereof.
In the light-emitting device according to an embodiment, b17 may be 1 or more,
In the light-emitting device according to an embodiment, a moiety represented by
in Formula 1 may be represented by one of Formulae 1-1-a to 1-20-a:
In Formulae 1-1-a to 1-20-a,
In the light-emitting device according to an embodiment, a moiety represented by
in Formula 1 may be represented by one of Formulae 1-1-b to 1-17-b:
In Formulae 1-1-b to 1-17-b,
In the light-emitting device according to an embodiment, a first host may include at least one compound represented by H1 to H25:
In the light-emitting device according to an embodiment, the second host may include a compound represented by Formula 2:
In Formula 2,
L21 and L22 may each independently be a single bond, a substituted or unsubstituted C3-C60 carbocyclic group, or a substituted or unsubstituted C1-C60 heterocyclic group,
For example, substituted or unsubstituted CY23 and substituted or unsubstituted CY24 may each independently be a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, a cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a thiophene group, a furan group, an indole group, a benzoborole group, a benzophosphole group, an indene group, a benzosilole group, a benzogermole group, a benzothiophene group, a benzoselenophene group, a benzofuran group, a carbazole group, a dibenzoborole group, a dibenzophosphole group, a fluorene group, a dibenzosilole group, a dibenzogermole group, a dibenzothiophene group, a dibenzoselenophene group, a dibenzofuran group, a dibenzothiophene 5-oxide group, a 9H-fluorene-9-one group, a dibenzothiophene 5,5-dioxide group, an azaindole group, an azabenzoborole group, an azabenzophosphole group, an azaindene group, an azabenzosilole group, an azabenzogermole group, an azabenzothiophene group, an azabenzoselenophene group, an azabenzofuran group, an azacarbazole group, an azadibenzoborole group, an azadibenzophosphole group, an azafluorene group, an azadibenzosilole group, an azadibenzogermole group, an azadibenzothiophene group, an azadibenzoselenophene group, an azadibenzofuran group, an azadibenzothiophene 5-oxide group, an aza-9H-fluorene-9-one group, an azadibenzothiophene 5,5-dioxide group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isooxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a 5,6,7,8-tetrahydroisoquinoline group, or a 5,6,7,8-tetrahydroquinoline group.
For example, each of the groups Cy23 and Cy24 above, the groups Cy23 and Cy24 may be substituted with at least one R10a. R10a may be the same as described herein in connection with R23.
In Formula 2, X21 may be N or C(R21a), X22 may be N or C(R22a), and X23 may be N or C(R23a).
In an embodiment, at least one of X21 to X23 may be N.
For example, at least one of X21 to X23 may be N, two or X21 to X23 may be N, and X21 to X23 may each be N.
In Formula 2, L21 and L22 may each independently be a single bond, a substituted or unsubstituted C3-C60 carbocyclic group, or a substituted or unsubstituted C1-C60 heterocyclic group.
For example, L21 and L22 may each independently be: a single bond; or
In one embodiment, L21 and L22 may each independently be: a single bond; or a group represented by any one of Formulae L-1 to L-12:
In Formulae L-1 to L-12,
In an embodiment, R21 and R22 may each independently be a C6-C60 aryl group unsubstituted or substituted with at least one R10a, a group represented by Formula 2A, or a group represented by Formula 2B, and
In Formulae 2A and 2B,
In the light-emitting device according to an embodiment, a second host may include at least one compound represented by E1 to E18:
In the light-emitting device according to an embodiment, a first phosphorescent emitter and a second phosphorescent emitter, the latter of which may be identical to or different from the first phosphorescent emitter.
In the light-emitting device according to an embodiment, the first phosphorescent emitter and the second phosphorescent emitter may each independently include a compound represented by Formula 3 or Formula 5:
M51(L51)n51(L52)n52 Formula 5
In the light-emitting device according to an embodiment, M31 and M51 in Formulae 3 and 5 may each independently be beryllium (Be), magnesium (Mg), aluminum (Al), calcium (Ca), titanium (Ti), manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), zirconium (Zr), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), rhenium (Re), platinum (Pt), or gold (Au).
In the light-emitting device according to an embodiment, M31 and M51 in Formulae 3 and 5 may each independently be palladium (Pd), platinum (Pt), or gold (Au).
In the light-emitting device according to an embodiment, in Formula 3, n34 may be 0, X31 may be C, and a bond between X11 and M may be a coordinate bond.
In the light-emitting device according to an embodiment, in Formula 3, CY31 to CY34 may each independently be
In the light-emitting device according to an embodiment, in Formula 3, CY32 to CY34 may each independently include a benzene group, a naphthalene group, an anthracene group, a phenanthrene group, a triphenylene group, a pyrene group, a chrysene group, cyclopentadiene group, a 1,2,3,4-tetrahydronaphthalene group, a furan group, a thiophene group, a silole group, an indene group, a fluorene group, an indole group, a carbazole group, a benzofuran group, a dibenzofuran group, a benzothiophene group, a dibenzothiophene group, a benzosilole group, a dibenzosilole group, an azafluorene group, an azacarbazole group, an azadibenzofuran group, an azadibenzothiophene group, an azadibenzosilole group, a pyridine group, a pyrimidine group, a pyrazine group, a pyridazine group, a triazine group, a quinoline group, an isoquinoline group, a quinoxaline group, a quinazoline group, a phenanthroline group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, a tetrazole group, an oxazole group, an isooxazole group, a thiazole group, an isothiazole group, an oxadiazole group, a thiadiazole group, a benzopyrazole group, a benzimidazole group, an indazole group, a benzoxazole group, a benzothiazole group, a benzoxadiazole group, a benzothiadiazole group, a benzotriazole group, a diazaindene group, a triazaindene group, a 5,6,7,8-tetrahydroisoquinoline group, or a 5,6,7,8-tetrahydroquinoline group, each unsubstituted or substituted with at least one R10a. R10a may be the same as described herein in connection with R23.
In the light-emitting device according to an embodiment, the first phosphorescent emitter and the second phosphorescent emitter may each independently include an organometallic compound represented by Formula 3-1 or Formula 3-2:
In the light-emitting device according to an embodiment, in Formulae 3-1 and 3-2,
In the light-emitting device according to an embodiment, in Formulae 3-1 and 3-2, at least one of R311 to R317 may include a C1-C20 alkyl group, a C6-C60 aryl group, or a C7-C60 arylalkyl group, each unsubstituted or substituted with a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a phenyl group, a cumyl group, or any combination thereof.
In the light-emitting device according to an embodiment, the first phosphorescent emitter and the second phosphorescent emitter may each independently include at least one selected from groups represented by P1 to P52:
In the light-emitting device according to an embodiment, the first phosphorescent emitter and the second phosphorescent emitter may each independently be included at about 0 wt % to about 10 wt %.
In the light-emitting device according to an embodiment, a first fluorescent emitter may be represented by Formula 4:
In the light-emitting device according to an embodiment, in Formula 4, Z may be B.
In the light-emitting device according to an embodiment, the first fluorescent emitter may be represented by any one of Formulae 4-1 to 4-8:
In the light-emitting device according to an embodiment, the first fluorescent emitter may include at least one group represented by D1 to D30:
In the light-emitting device according to an embodiment, the first fluorescent emitter may be included in the emission layer at about 0 wt % to about 10 wt %.
In the light-emitting device according to an embodiment, a thickness of the second emission layer may be greater than a thickness of the first emission layer.
In the light-emitting device according to an embodiment, the thickness of the first emission layer may be less than or equal to half (or 50%) of a total thickness of the first emission layer and the second emission layer. For example, when the total thickness of the first emission layer and the second emission layer is 400 Å, the thickness of the first emission layer may be less than or equal to 200 Å.
In the light-emitting device according to an embodiment, the thickness of the first emission layer may be greater than or equal to one-tenth (or 10%) based on the total thickness of the first emission layer and the second emission layer. For example, when the total thickness of the first emission layer and the second emission layer is 400 Å, the thickness of the first emission layer may be greater than or equal to 40 Å.
In the light-emitting device according to an embodiment, the thickness of the first emission layer may be 20% to 40% based on the total thickness (100%) of the first emission layer and the second emission layer.
In the light-emitting device according to an embodiment, the anode may be a hole injection electrode, the cathode may be an electron injection electrode, and the first emission layer may be arranged between the anode and the second emission layer.
The light-emitting device according to an embodiment may further include an organic layer, and the organic layer may be arranged on the cathode. In addition, the organic layer may have a microcavity structure.
In the light-emitting device according to an embodiment, Tdecay(1) may be about 0.5 microseconds (μs) to about 5 μs. Tdecay(1) may be about 1 μs to about 4 μs. Tdecay(1) may be about 1.5 μs to about 3 μs.
In the light-emitting device according to an embodiment, Tdecay(2) may be about 1 μs to about 20 μs. Tdecay(2) may be about 2 μs to about 15 μs. Tdecay(2) may be about 3 μs to about 10 μs.
In the light-emitting device according to an embodiment, a ratio of Tdecay(2) to Tdecay(1) may be greater than 1:1 to less than or equal to 40:1. The ratio of Tdecay(2) to Tdecay(1) may be about 2:1 to about 20:1. The ratio of Tdecay(2) to Tdecay(1) may be about 2.5:1 to about 10:1.
As for the decay time Tdecay(1) of the first emission layer and the decay time Tdecay(2) of the second emission layer, when the aforementioned numerical range is satisfied, lifespan of the light-emitting device including the first emission layer and the second emission layer may be improved.
For example, the organic light-emitting device may include an anode, a cathode, and an interlayer, and the interlayer may include a first emission layer and a second emission layer. The interlayer may further include a hole transport region arranged between the anode and the first emission layer and an electron transport region arranged between the second emission layer and the cathode. The hole transport region may include a hole injection layer, a hole transport layer, an electron blocking layer, an auxiliary layer, or any combination thereof. The electron transport region may include a buffer layer, a hole blocking layer, an electron transport layer, an electron injection layer, or any combination thereof.
The light-emitting device according to an embodiment may include the first emission layer and the second emission layer. The first emission layer may be formed on the anode, and the second emission layer may be formed on the first emission layer. The first emission layer may include the first phosphorescent emitter, and the second emission layer may include the first fluorescent emitter and a second phosphorescent emitter.
In addition, a decay time Tdecay(1) of the first emission layer may be shorter than a decay time Tdecay(2) of the second emission layer, and excitons formed in the first emission layer may be annihilated faster than excitons formed in the second emission layer. Accordingly, an exciton concentration in the first emission layer may be less than an exciton concentration in the second emission layer, and thus, decomposition of an emitter and a host which may occur during annihilation in the excited state, such as triplet-triplet annihilation (TTA) or triplet-polaron annihilation (TPA) may be relatively more suppressed in the first emission layer.
The thickness of the first emission layer may be adjusted such that the exciton distribution is formed mainly in the first emission layer. Accordingly, decomposition of emitter and host due to formation of exciton in the first emission layer may be further suppressed. As a result, lifespan of the light-emitting device including the first emission layer and the second emission layer may be improved. Moreover, as the second emission layer is included on a surface of the first emission layer, emission characteristics of the emission layer may be further improved.
The
A substrate (not shown) may be additionally located under the anode 11 or on the cathode 19. The substrate may be a conventional substrate used in organic light-emitting devices, e.g., a glass substrate or a transparent plastic substrate, each having excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and water repellency.
The anode 11 may be, for example, formed by depositing or sputtering a material for anode on the substrate. The material for anode may be selected from materials with a high work function to facilitate hole injection. The anode 11 may be a reflective electrode, a semi-transmissive electrode, or a transmissive electrode. The material for anode may be indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO2), or zinc oxide (ZnO). In one or more embodiments, the material for anode may be metal, such as magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), or magnesium-silver (Mg—Ag).
The anode 11 may have a single-layered structure or a multi-layered structure including two or more layers. For example, the anode 11 may have a three-layered structure of ITO/Ag/ITO, but embodiments are not limited thereto.
The interlayer 15 may be arranged on the anode 11.
The interlayer 15 may include: a hole transport region; an emission layer; and an electron transport region.
The emission layer may include a first emission layer and a second emission layer. The first emission layer may be formed on the anode 11, and the second emission layer may be formed on the first emission layer.
In the light-emitting device according to an embodiment, the emission layer may include the first emission layer and the second emission layer. A decay time Tdecay(1) of the first emission layer may be shorter than a decay time Tdecay(2) of the second emission layer.
The first emission layer may include the phosphorescent emitter, the first host, and/or the second host. The second emission layer may include the same or different phosphorescent emitter, a fluorescent emitter, the same or different first host, and/or the same or different second host.
In addition, the first emission layer may be arranged between the anode 11 and the second emission layer. As a result, holes emitted from the anode 11 may arrive at the first emission layer faster than the second emission layer.
The hole transport region may be between the anode 11 and the emission layer.
The hole transport region may include a hole injection layer, a hole transport layer, an electron blocking layer, a buffer layer, or any combination thereof.
The hole transport region may include only either a hole injection layer or a hole transport layer. Alternatively, the hole transport region may have a hole injection layer/hole transport layer structure or a hole injection layer/hole transport layer/electron blocking layer structure, wherein, for each structure, respective layers are sequentially stacked in this stated order from the anode 11.
When the hole transport region includes a hole injection layer, the hole injection layer may be formed on the anode 11 by using one or more suitable methods, such as vacuum deposition, spin coating, casting, and Langmuir-Blodgett (LB) deposition.
When a hole injection layer is formed by vacuum deposition, the deposition conditions may vary according to a material that is used to form the hole injection layer, and the structure and thermal characteristics of the hole injection layer. For example, the deposition conditions may include a deposition temperature of about 100° C. to about 500° C., a vacuum pressure of about 10−8 torr to about 10−3 torr, and a deposition rate of about 0.01 Å/sec to about 100 Å/sec. However, the deposition conditions are not limited thereto.
When the hole injection layer is formed using spin coating, coating conditions may vary according to the material used to form the hole injection layer, and the structure and thermal properties of the hole injection layer. For example, a coating speed may be from about 2,000 rpm to about 5,000 rpm, and a temperature at which a heat treatment is performed to remove a solvent after coating may be from about 80° C. to about 200° C. However, the coating conditions are not limited thereto.
The conditions for forming the hole transport layer and the electron blocking layer may be the same as the conditions for forming the hole injection layer.
The hole transport region may include at least one of m-MTDATA, TDATA, 2-TNATA, NPB, β-NPB, TPD, spiro-TPD, spiro-NPB, methylated NPB, TAPC, HMTPD, 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA), polyaniline/dodecylbenzenesulfonic acid (PANI/DBSA), poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS), polyaniline/camphor sulfonic acid (PANI/CSA), (polyaniline)/poly(4-styrenesulfonate) (PANI/PSS), a compound represented by Formula 201, and a compound represented by Formula 202:
R101 to R108, R111 to R119 and R121 to R124 in Formulae 201 and 202 may each independently be:
According to an embodiment, the compound represented by Formula 201 may be represented by Formula 201A below, but embodiments of the disclosure are not limited thereto:
R101, R111, R112, and Rice in Formula 201A are each the same as described in the specification.
For example, the compound represented by Formula 201, and the compound represented by Formula 202 may include compounds HT1 to HT20 illustrated below, but are not limited thereto:
A thickness of the hole transport region may be in the range of about 100 Å to about 10,000 Å, for example, about 100 Å to about 1,000 Å. When the hole transport region includes at least one of 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, for example, about 100 Å to about 1,000 Å, and a thickness of the hole transport layer may be in a range of about 50 Å to about 2,000 Å, for example, 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, satisfactory hole transporting characteristics may be obtained without a substantial increase in driving voltage.
The hole transport region may further include, in addition to these materials, a charge-generation material for the improvement of conductive properties. The charge-generation material may be homogeneously or non-homogeneously dispersed in the hole transport region.
The charge-generation material may be, for example, a p-dopant. The p-dopant may be one selected from a quinone derivative, a metal oxide, and a cyano group-containing compound, but embodiments of the disclosure are not limited thereto. For example, non-limiting examples of the p-dopant are: a quinone derivative, such as tetracyanoquinonedimethane (TCNQ), 2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinonedimethane (F4-TCNQ), and F6-TCNQ; a metal oxide, such as a tungsten oxide and a molybdenium oxide; and a cyano group-containing compound, such as Compounds HT-D1 and F12, but are not limited thereto:
The hole transport region may include a buffer layer.
The buffer layer may compensate for an optical resonance distance according to a wavelength of light emitted from the emission layer, and thus, efficiency of the light-emitting device may be improved.
The emission layer may be formed on the hole transport region by using one or more suitable methods, such as vacuum deposition, spin coating, casting, or LB deposition. When the emission layer is formed by vacuum deposition or spin coating, the deposition or coating conditions may be similar to those applied in forming the hole injection layer although the deposition or coating conditions may vary according to a material that is used to form the hole transport layer.
In addition, when the hole transport region includes an electron blocking layer, a material for the electron blocking layer may be selected from materials for the hole transport region described above and materials for a host to be explained later. However, the material for the electron blocking layer is not limited thereto. For example, when the hole transport region includes an electron blocking layer, a material for the electron blocking layer may be mCP, which will be explained later.
The amount of dopant in the emission layer may be from 0.1 parts by weight to 20 parts by weight based on 100 parts by weight of the emission layer.
The total thickness of the emission layer may be about 100 Å to about 1,000 Å. In addition, the total thickness of the emission layer may be about 200 Å to about 600 Å.
When the organic light-emitting device is a full-color organic light-emitting device, the emission layer may be patterned into a red emission layer, a green emission layer, and a blue emission layer. In one or more embodiments, due to a stacked structure including a red emission layer, a green emission layer, and/or a blue emission layer, the emission layer may emit white light.
An electron transport region may be located on the emission layer.
The electron transport region may include a hole blocking layer, an electron transport layer, an electron injection layer, or a combination thereof.
For example, the electron transport region may have a hole blocking layer/electron transport layer/electron injection layer structure or an electron transport layer/electron injection layer structure, and the structure of the electron transport region is not limited thereto. The electron transport layer may have a single-layered structure or a multi-layered structure including two or more different materials.
Conditions for forming the hole blocking layer, the electron transport layer, and the electron injection layer which constitute the electron transport region may be understood by referring to the conditions for forming the hole injection layer.
When the electron transport region includes a hole blocking layer, the hole blocking layer may include, for example, at least one of BCP, Bphen, and BAlq but embodiments of the disclosure are not limited thereto:
A thickness of the hole blocking layer may be in a range of about 20 Å to about 1,000 Å, for example, about 30 Å to about 300 Å. When the thickness of the hole blocking layer is within these ranges, excellent hole blocking characteristics may be obtained without a substantial increase in driving voltage.
The electron transport layer may further include at least one selected from BCP, Bphen, Alq3, BAlq, TAZ, and NTAZ:
In one or more embodiments, the electron transport layer may include at least one of ET1 to ET25, but are not limited thereto:
A thickness of the electron transport layer may be in the range of about 100 Å to about 1,000 Å, for example, about 150 Å to about 500 Å. When the thickness of the electron transport layer is within the range described above, the electron transport layer may have satisfactory electron transporting characteristics without a substantial increase in driving voltage.
The electron transport layer may include a metal-containing material in addition to the material as described above.
The metal-containing material may include a Li complex. The Li complex may include, for example, Compound ET-D1 (lithium quinolate, LiQ) or ET-D2:
The electron transport region may also include an electron injection layer that promotes the flow of electrons from the cathode 19 thereinto.
The electron injection layer may include LiF, NaCl, CsF, Li2O, BaO, or a combination thereof.
A thickness of the electron injection layer may be in a range of about 1 Å to about 100 Å, and, for example, about 3 Å to about 90 Å. When the thickness of the electron injection layer is within the ranges above, satisfactory electron injection characteristics may be obtained without a substantial increase in driving voltage.
The cathode may be arranged on the interlayer. A material for cathode may be a metal, an alloy, an electrically conductive compound, or a combination thereof, which has a relatively low work function. For example, lithium (Li), magnesium (Mg), aluminum (Al), aluminum-lithium (Al—Li), calcium (Ca), magnesium-indium (Mg—In), or magnesium-silver (Mg—Ag) may be used as the material for forming the cathode. In an embodiment, to manufacture a top-emission type light-emitting device, a transmissive electrode formed using ITO or IZO may be used as the cathode 19.
Hereinbefore, the organic light-emitting device has been described with reference to the FIGURE, but embodiments of the disclosure are not limited thereto.
The term “C1-C60 alkyl group” as used herein refers to a linear or branched saturated aliphatic hydrocarbon monovalent group having 1 to 60 carbon atoms, and non-limiting examples thereof include a methyl group, an ethyl group, a propyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isoamyl group, and a hexyl group. The term “C1-C60 alkylene group” as used herein refers to a divalent group having the same structure as the C1-C60 alkyl group.
The term “C1-C60 alkoxy group” used herein refers to a monovalent group represented by —OA101 (wherein A101 is the C1-C60 alkyl group), and examples thereof include a methoxy group, an ethoxy group, and an isopropyloxy group.
The term “C2-C60 alkenyl group” as used herein refers to a hydrocarbon group formed by substituting at least one carbon-carbon double bond in the middle or at the terminus of the C2-C60 alkyl group, and examples thereof include an ethenyl group, a propenyl group, and a butenyl group. The term “C2-C60 alkenylene group” as used herein refers to a divalent group having the same structure as the C2-C60 alkenyl group.
The term “C2-C60 alkynyl group” as used herein refers to a hydrocarbon group formed by substituting at least one carbon-carbon triple bond in the middle or at the terminus of the C2-C60 alkyl group, and examples thereof include an ethynyl group and a propynyl group. The term “C2-C60 alkynylene group” as used herein refers to a divalent group having the same structure as the C2-C60 alkynyl group.
The term “C3-C10 cycloalkyl group” as used herein refers to a monovalent saturated hydrocarbon monocyclic group having 3 to 10 carbon atoms, and examples thereof include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group. The term “C3-C10 cycloalkylene group” as used herein refers to a divalent group having the same structure as the C3-C10 cycloalkyl group.
The term “C1-C10 heterocycloalkyl group” as used herein refers to a monovalent monocyclic group having at least one heteroatom selected from N, O, P, Si, and S as a ring-forming atom and 1 to 10 carbon atoms, and examples thereof include a tetrahydrofuranyl group and a tetrahydrothiophenyl group. The term “C1-C10 heterocycloalkylene group” as used herein refers to a divalent group having the same structure as the C1-C10 heterocycloalkyl group.
The term “C3-C10 cycloalkenyl group” as used herein refers to a monovalent monocyclic group that has 3 to 10 carbon atoms and at least one carbon-carbon double bond in the ring thereof and no aromaticity, and non-limiting examples thereof include a cyclopentenyl group, a cyclohexenyl group, and a cycloheptenyl group. The term “C3-C10 cycloalkenylene group” as used herein refers to a divalent group having the same structure as the C3-C10 cycloalkenyl group.
The term “C1-C10 heterocycloalkenyl group” as used herein refers to a monovalent monocyclic group that has at least one heteroatom selected from N, O, P, Si, and S as a ring-forming atom, 1 to 10 carbon atoms, and at least one carbon-carbon double bond in its ring. Examples of the C1-C10 heterocycloalkenyl group are a 2,3-dihydrofuranyl group, and a 2,3-dihydrothiophenyl group. The term “C1-C10 heterocycloalkenylene group” as used herein refers to a divalent group having the same structure as the C1-C10 heterocycloalkenyl group.
The term “C6-C60 aryl group” as used herein refers to a monovalent group having a carbocyclic aromatic system having 6 to 60 carbon atoms, and the term “C6-C60 arylene group” as used herein refers to a divalent group having a carbocyclic aromatic system having 6 to 60 carbon atoms. Examples of the C6-C60 aryl group include a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a pyrenyl group, and a chrysenyl group. When the C6-C60 aryl group and the C6-C60 arylene group each include two or more rings, the rings may be fused to each other. The C7-C60 alkylaryl group refers to a C6-C60 aryl group substituted with at least one C1-C60 alkyl group.
The term “C1-C60 heteroaryl group” as used herein refers to a monovalent group having a carbocyclic aromatic system that has at least one heteroatom selected from N, O, P, Si, and S as a ring-forming atom, and 1 to 60 carbon atoms. The term “C1-C60 heteroarylene group” as used herein refers to a divalent group having a carbocyclic aromatic system that has at least one heteroatom selected from N, O, P, and S as a ring-forming atom, and 1 to 60 carbon atoms. Examples of the C1-C60 heteroaryl group include a pyridinyl group, a pyrimidinyl group, a pyrazinyl group, a pyridazinyl group, a triazinyl group, a quinolinyl group, and an isoquinolinyl group. When the C6-C60 heteroaryl group and the C6-C60 heteroarylene group each include two or more rings, the rings may be fused to each other. The C2-C60 alkylheteroaryl group refers to a C1-C60 heteroaryl group substituted with at least one C1-C60 alkyl group.
The term “C6-C60 aryloxy group” as used herein indicates —OA102 (wherein A102 is the C6-C60 aryl group), and the term “C6-C60 arylthio group” as used herein indicates —SA103 (wherein A103 is the C6-C60 aryl group).
The term “C1-C60 heteroaryloxy group” as used herein refers to —OA104 (wherein A104 is the C1-C60 heteroaryl group), and the term “C1-C60 heteroarylthio group” as used herein refers to —SA105 (wherein A105 is the C1-C60 heteroaryl group).
The term “monovalent non-aromatic condensed polycyclic group” as used herein refers to a monovalent group (for example, having 8 to 60 carbon atoms) having two or more rings condensed to each other, only carbon atoms as ring-forming atoms, and no aromaticity in its entire molecular structure. Examples of the monovalent non-aromatic condensed polycyclic group include a fluorenyl group. The term “divalent non-aromatic condensed polycyclic group” as used herein refers to a divalent group having the same structure as the monovalent non-aromatic condensed polycyclic group described above.
The term “monovalent non-aromatic condensed heteropolycyclic group” as used herein refers to a monovalent group (for example, having 2 to 60 carbon atoms) having two or more rings condensed with each other, a heteroatom selected from N, O, P, Si, and S, other than carbon atoms, as a ring-forming atom, and no aromaticity in its entire molecular structure. Examples of the monovalent non-aromatic condensed heteropolycyclic group include a carbazolyl 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 described above.
The term “C5-C30 carbocyclic group” as used herein refers to a saturated or unsaturated cyclic group having, as a ring-forming atom, 5 to 30 carbon atoms only. The C5-C30 carbocyclic group may be a monocyclic group or a polycyclic group.
The term “C1-C30 heterocyclic group” as used herein refers to a saturated or unsaturated cyclic group having, as a ring-forming atom, at least one heteroatom selected from N, O, Si, P, and S other than 1 to 30 carbon atoms. The C1-C30 heterocyclic group may be a monocyclic group or a polycyclic group.
The term “at least one substituent” as pertaining to, for example, the substituted C5-C30 carbocyclic group, the substituted C1-C30 heterocyclic group, the substituted C1-C60 alkyl group, the substituted C2-C60 alkenyl group, the substituted C2-C60 alkynyl group, the substituted C1-C60 alkoxy group, the substituted C3-C10 cycloalkyl group, the substituted C1-C10 heterocycloalkyl group, the substituted C3-C10 cycloalkenyl group, the substituted C1-C10 heterocycloalkenyl group, the substituted C6-C60 aryl group, the substituted C7-C60 alkylaryl group, the substituted C6-C60 aryloxy group, the substituted C6-C60 arylthio group, the substituted C1-C60 heteroaryl group, the substituted C2-C60 alkyl heteroaryl group, the substituted monovalent non-aromatic condensed polycyclic group, and the substituted monovalent non-aromatic condensed heteropolycyclic group may be one of the following:
Hereinafter, a compound and an organic light-emitting device according to embodiments are described in detail with reference to Synthesis Example and Examples. However, the organic light-emitting device is not limited thereto. The wording “B was used instead of A” used in describing Synthesis Examples means that an amount of A used was identical to an amount of B used, in terms of a molar equivalent.
A silver-coated glass substrate and having an indium tin oxide (ITO) electrode (an anode) deposited thereon at a thickness of 1,500 Å was cleaned by ultrasonication using distilled water. After the ultrasonication in distilled water, sequential ultrasonication was performed in isopropyl alcohol, acetone, and methanol, and the glass substrate was dried and transferred to a plasma cleaner. The glass substrate was cleaned by using oxygen plasma for 5 minutes, and then transferred to a vacuum laminator.
Compound HT3 was deposited on the ITO electrode of the glass substrate to form a hole transport layer having a thickness of 1,000 Å, and mCP was deposited on the hole transport layer to form an electron blocking layer having a thickness of 100 Å, thereby forming a hole transport region.
A first phosphorescent emitter (P31), a first host (H1), and a second host (H2) were co-deposited on the hole transport region at a weight ratio of 13:57:30 to form a first emission layer having a thickness of 100 Å. A first phosphorescent emitter (P31), a first fluorescent emitter (D3), a first host (H1), and a second host (H2) were co-deposited on the first emission layer at a weight ratio of 13:1:56:30 to form a second emission layer having a thickness of 300 Å.
BCP was vacuum-deposited on the second emission layer to form a hole blocking layer having a thickness of 100 Å. Compound ET3 and LiQ were then co-deposited on the hole blocking layer to form an electron transport layer having a thickness of 300 Å. Next, Yb was deposited on the electron transport layer to form an electron injection layer having a thickness of 10 Å. A cathode having a thickness of 130 Å was formed on the electron injection layer by using Ag and Mg (with a respective weight ratio of 87:13). An organic layer of Compound HT3 having a thickness of 700 Å was formed over the cathode, thereby completing the manufacture of a top-emission organic light-emitting device having a microcavity effect.
The preparation was performed in the same manner as in Example 1, except that the first emission layer was excluded, and a thickness of the second emission layer was 400 Å.
The preparation was performed in the same manner as in Example 1, except that a thickness of the first emission layer was 400 Å, and the second emission layer was excluded.
The preparation was performed in the same manner as in Example 1, except that a thickness of the first emission layer was 200 Å, and a thickness of the second emission layer was 200 Å.
A decay time (Tdecay) of the first emission layer and the second emission layer of Example 1 was measured. Each of the first emission layer and the second emission layer was vacuum-deposited on a quartz substrate to obtain a film. Then, by measuring a time-resolved photoluminescence (TRPL) spectrum of each film at room temperature, a main peak, full-width half maximum (FWHM), and color coordinates (CIE) of the first emission layer and the second emission layer were measured, a decay time of the first emission layer and the second emission layer was calculated. Picoquant Fluo Time 300 was used as an evaluation device. The measured decay time is shown in Table 1 below.
Color coordinates, external quantum efficiency, and lifespan (T95) of light-emitting devices according to Example 1 and Comparative Examples 1, 2, and 3 were measured, and the results are shown in Table 2 below. As evaluation apparatuses, a current-voltage meter (Keithley 2400) and a luminance meter (Minolta Cs-1000A) were used. A relative time taken for the luminance to reach 95% of the initial luminance (100%) was evaluated as the lifespan (T95). The external quantum efficiency and the lifespan were shown in relative values based on the values of the light-emitting device of Comparative Example 1.
From Table 1, it is confirmed that light-emitting device according to Example 1 has improved lifespan, compared to light-emitting devices of Comparative Examples.
According to the one or more embodiments, a light-emitting device including a first emission layer and a second emission layer may have long lifespan characteristics. Accordingly, by using the light-emitting device, a high-quality electronic apparatus may be implemented.
It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments. While one or more embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0014402 | Feb 2023 | KR | national |
