Patent Application
20180198080
This application claims priority to Korean Patent Application No. 10-2017-0004165, filed on Jan. 11, 2017, in the Korean Intellectual Property Office, and all the benefits accruing therefrom under 35 U.S.C. § 119, the content of which is incorporated herein in its entirety by reference.
One or more embodiments relate to an organometallic compound, a composition containing the organometallic compound, and an organic light-emitting device.
Organic light-emitting devices (OLEDs) are self-emission devices, which produce full-color images, and which have wide viewing angles, high contrast ratios, short response times, and excellent characteristics in terms of brightness, driving voltage, and response speed, compared to the devices in the art.
In an example, an organic light-emitting device includes an anode, a cathode, and an organic layer disposed between the anode and the cathode, wherein the organic layer includes an emission layer. A hole transport region may be disposed between the anode and the emission layer, and an electron transport region may be disposed between the emission layer and the cathode. Holes provided from the anode may move toward the emission layer through the hole transport region, and electrons provided from the cathode may move toward the emission layer through the electron transport region. The holes and the electrons recombine in the emission layer to produce excitons. These excitons transit from an excited state to a ground state, thereby generating light.
Various types of organic light emitting devices are known. However, there still remains a need in OLEDs having low driving voltage, high efficiency, high brightness, and long lifespan.
One or more embodiments include a novel organometallic compound, a composition containing the organometallic compound, and an organic light-emitting device.
Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.
According to one or more embodiments, an organometallic compound is represented by Formula 1:
Formula 1
In Formula 1,
According to one or more embodiments, a composition containing the organometallic compound includes a first organometallic compound represented by Formula 1 and a second organometallic compound represented by Formula 2:
In Formulae 1 and 2,
According to one or more embodiments, an organic light-emitting device includes:
The organometallic compound may act as a dopant in the organic layer.
These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings in which:
Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain aspects. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.
It will be understood that when an element is referred to as being “on” another element, it can be directly in contact with 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 of the present embodiments.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. 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.
The term “or” means “and/or.” 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.
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 general inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Exemplary embodiments are described herein with reference to cross section illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, a region illustrated or described as flat may, typically, have rough and/or nonlinear features. Moreover, sharp angles that are illustrated may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the present claims.
“About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” can mean within one or more standard deviations, or within +30%, 20%, 10%, 5% of the stated value.
In an embodiment, an organometallic compound is provided. The organometallic compound according to an embodiment may be represented by Formula 1 below:
M1 in Formula 1 may be selected from a first-row transition metal of the Periodic Table of Elements, a second-row transition metal of the Periodic Table of Elements, and a third-row transition metal of the Periodic Table of Elements.
For example, M1 may be selected from iridium (Ir), platinum (Pt), osmium (Os), titanium (Ti), zirconium (Zr), hafnium (Hf), europium (Eu), terbium (Tb), thulium (Tm), and rhodium (Rh).
In one or more embodiments, M1 may be iridium, but embodiments of the present disclosure are not limited thereto.
In Formula 1, n1 may be 1, 2, or 3, wherein, when n1 is two or more, two or more ligands represented by
in Formula 1 (wherein * and *′ each indicate a binding site to M1 in Formula 1) may be identical to or different from each other, L2 may be selected from a monodentate ligand and a bidentate ligand, and n2 may be 0, 1, 2, 3, or 4, wherein, when n2 is two or more, two or more groups L2 may be identical to or different from each other. L2 is the same as described below.
In one or more embodiments, in Formula 1, M1 may be Ir or Os, and the sum of n1 and n2 may be 3 or 4; or M1 may be Pt, and the sum of n1 and n2 may be 2.
In one or more embodiments, in Formula 1, M1 may be Ir, n1 may be 3, and n2 may be 0, but embodiments of the present disclosure are not limited thereto.
In one or more embodiments, in Formula 1, M1 may be Ir, n1 may be 3, n2 may be 0, and three ligands represented by
may be identical to one another.
X1 and X2 in Formula 1 may each independently be carbon or nitrogen.
In one or more embodiments, X1 and X2 may each be carbon, but embodiments of the present disclosure are not limited thereto.
CY1 and CY2 in Formula 1 may each independently be selected from a C5-C30 carbocyclic group and a C2-C30 heterocyclic group.
For example, CY1 and CY2 may each independently be selected from a cyclopentene group, a cyclohexene group, a benzene group, a pyridine group, a pyrimidine group, a pyridazine group, a pyrazine group, a triazine group, a pyrrole group, a pyrazole group, an imidazole group, a triazole group, an oxazole group, an isoxazole group, an oxadiazole group, a thiazole group, an isothiazole group, and a thiadiazole group.
In one or more embodiments, CY1 and CY2 may each independently be a benzene group, a pyridine group, or a pyrimidine group.
In one or more embodiments, CY1 and CY2 may each be a benzene group, but embodiments of the present disclosure are not limited thereto.
R1, R2, and R11 to R16 in Formula 1 may each independently be selected from hydrogen, deuterium, —F, —Cl, —Br, —I, —SF5, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a substituted or unsubstituted C1-C60 alkyl group, a substituted or unsubstituted C2-C60 alkenyl group, a substituted or unsubstituted C2-C60 alkynyl group, a substituted or unsubstituted C1-C60 alkoxy group, a substituted or unsubstituted C3-C10 cycloalkyl group, a substituted or unsubstituted C1-C10 heterocycloalkyl group, a substituted or unsubstituted C3-C10 cycloalkenyl group, a substituted or unsubstituted C1-C10 heterocycloalkenyl group, a substituted or unsubstituted C6-C60 aryl group, a substituted or unsubstituted C6-C60 aryloxy group, a substituted or unsubstituted C6-C60 arylthio group, a substituted or unsubstituted C7-C60 arylalkyl group, a substituted or unsubstituted C1-C60 heteroaryl group, a substituted or unsubstituted C1-C60 heteroaryloxy group, a substituted or unsubstituted C1-C60 heteroarylthio group, a substituted or unsubstituted C2-C60 heteroarylalkyl group, a substituted or unsubstituted monovalent non-aromatic condensed polycyclic group, a substituted or unsubstituted monovalent non-aromatic condensed heteropolycyclic group, —N(Q1)(Q2), —Si(Q3)(Q4)(Q5), —B(Q6)(Q7), and —P(═O)(Q8)(Q9). Q1 to Q09 are the same as described herein.
For example, R1, R2, and R11 to R16 may each independently be selected from: hydrogen, deuterium, —F, —Cl, —Br, —I, a hydroxyl group, a cyano group, a nitro group, an amino group, an amidino group, a hydrazine group, a hydrazone group, a carboxylic acid group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, —SF5, a C1-C20 alkyl group, and a C1-C20 alkoxy group;
In one or more embodiments, R1, R2, and R11 to R16 may each independently be selected from:
Two or more neighboring groups of R1, R2, R11 to R13, CY1, and CY2 in Formula 1 may optionally be linked to form a C5-C30 carbocyclic group unsubstituted or substituted with at least one R101 (for example, a 5-membered or 6-membered carbocyclic group unsubstituted or substituted with at least one R101), or a C2-C30 heterocyclic group unsubstituted or substituted with at least one R101 (for example, a 5-membered or 6-membered heterocyclic group unsubstituted or substituted with at least one R101). R101 is the same as described in connection with R1.
a1 and a2 in Formula 1 respectively indicate the number of groups R1 and the number of groups R2 and may each independently be an integer from 0 to 5.
For example, a1 and a2 may each independently be 0, 1, or 2, but embodiments of the present disclosure are not limited thereto.
R19 and R20 in Formula 1 may each independently be selected from hydrogen, deuterium, a C1-C30 alkyl group, a C1-C30 alkyl group substituted with at least one deuterium, a C6-C60 aryl group, and a C6-C60 aryl group substituted with at least one selected from a C1-C30 alkyl group and deuterium.
In one or more embodiments, R1, R2, R11 to R16, R19, and R20 in Formula 1 may each independently be selected from:
In one or more embodiments, at least one of R1, R2, R11 to R16, R19, and R20 in Formula 1 may be a deuterium-containing substituent, and the deuterium-containing substituent may be selected from:
For example, the deuterium-containing substituent may be selected from:
In one or more embodiments, the deuterium-containing substituent may be selected from:
In one or more embodiments, the deuterium-containing substituent may be selected from —D, —CH2D, —CHD2, —CD3, —CH2CH2D, —CH2CHD2, —CH2CD3, —CHDCH3, —CHDCH2D, —CHDCHD2, —CHDCD3, —CD2CH3, —CD2CH2D, —CD2CHD2, —CD2CD3, —CH2CH2CH2D, —CH2CH2CHD2, —CH2CH2CD3, —CH2CHDCH3, —CH2CHDCH2D, —CH2CHDCHD2, —CH2CHDCD3, —CH2CD2CH3, —CH2CD2CH2D, —CH2CD2CHD2, —CH2CD2CD3, —CHDCH2CH2D, —CHDCH2CHD2, —CHDCH2CD3, —CHDCHDCH3, —CHDCHDCH2D, —CHDCHDCHD2, —CHDCHDCD3, —CHDCD2CH3, —CHDCD2CH2D, —CHDCD2CHD2, —CHDCD2CD3, —CD2CH2CH2D, —CD2CH2CHD2, —CD2CH2CD3, —CD2CHDCH3, —CD2CHDCH2D, —CD2CHDCHD2, —CD2CHDCD3, —CD2CD2CH3, —CD2CD2CH2D, —CD2CD2CHD2, —CD2CD2CD3, —CH(CH3)(CH2D), —CH(CH3)(CHD2), —CH(CH2D)(CH2D), —CH(CH3)(CD3), —CH(CHD2)(CHD2), —CH(CH2D)(CD3), CH(CHD2)(CHD2), —CH(CHD2)(CD3), —CH(CD3)2, —CD(CH3)2, —CD(CH3)(CH2D), —CD(CH3)(CHD2), —CD(CH2D)(CH2D), —CD(CH3)(CD3), —CD(CHD2)(CHD2), CD(CH2D)(CD3), —CD(CHD2)(CHD2), —CD(CHD2)(CD3), —CD(CD3)2, and —C(CD3)3, but embodiments of the present disclosure are not limited thereto.
In one or more embodiments, the deuterium-containing substituent may be selected from deuterium, —CD3, —CD2H, —CDH2, —CH2CD2H, —CH2CDH2, —CHDCH3, —CHDCD2H, —CHDCDH2, —CHDCD3, —CD2CD3, —CD2CD2H, —CD2CDH2, and groups represented by Formulae 9-14 to 9-24, but embodiments of the present disclosure are not limited thereto.
In one or more embodiments, the ligand represented by
in Formula 1 (wherein * and *′ each indicate a binding site to M1 in Formula 1) may include at least one deuterium. Whether the ligand represented by
includes deuterium may be confirmed by analyzing the organometallic compound represented by Formula 1 through a 1H NMR spectrum or analyzing a molecular weight of the organometallic compound by using a molecular weight measurement apparatus such as matrix-assisted laser desorption/ionization (MALDI) apparatus.
A compound (hereinafter, referred to as a “first standard compound”), which has the same backbone as the organometallic compound represented by Formula 1 but does not include deuterium, is prepared. A 1H NMR spectrum of the first standard compound and a 1H NMR spectrum of the organometallic compound represented by Formula 1 are obtained. Then, the number of hydrogens that are substituted with deuterium among hydrogens bonded at a specific position (specific carbon) of the organometallic compound represented by Formula 1 may be calculated by comparing integral values of signals of specific ppm selected from the measured spectrum.
In one or more embodiments, a compound (hereinafter, referred to as a “second standard compound”) which has the same backbone as the organometallic compound represented by Formula 1 and in which all hydrogens of the organometallic compound represented by Formula 1 are substituted with deuterium is assumed. The number of hydrogens of the organometallic compound represented by Formula 1 that are substituted with deuterium may be calculated by comparing a calculated molecular weight of the second standard compound with a molecular weight of the organometallic compound represented by Formula 1.
In one or more embodiments, at least one of R12, R14, R19, and R20 in Formula 1 may be a deuterium-containing substituent as described above. The deuterium-containing substituent is the same as described herein.
In one or more embodiments, at least one of R11, R12, R13, R19, and R20 in Formula 1 (for example, all of R11, R12, R13, R19, and R20) may a deuterium-containing substituent as described above. The deuterium-containing substituent is the same as described herein.
In one or more embodiments, R12 and R14 in Formula 1 may each independently be selected from:
The organometallic compound represented by Formula 1 may be represented by Formula 1-1:
In Formula 1-1, M1, n1, L2, n2, R11 to R16, R19, and R20 are the same as described herein, R1a to R1e are the same as described in connection with R1, and R2a to R2e are the same as described in connection with R2.
For example, at least one of R11 to R13 in Formula 1-1 may each independently be a deuterium-containing substituent as described herein.
In one or more embodiments, in Formula 1-1, at least one of R11 to R13, at least one of R1a to R1e, and at least one of R2a to R2e may each independently be a deuterium-containing substituent as described herein.
In one or more embodiments, R11 to R13, R1a to R1e, and R2a to R2e in Formula 1-1 may each independently be a deuterium-containing substituent as described herein, but embodiments of the present disclosure are not limited thereto.
In one or more embodiments, the organometallic compound represented by Formula 1 may be represented by Formula 1(1):
In Formula 1(1), M1, n1, L2, n2, R12, R14, R19, and R20 are the same as described herein, R1a and R1e are the same as described in connection with R1, and R2a and R2e are the same as described in connection with R2.
In one or more embodiments, at least one of R1a, R1e, R2a, R2e, R12, R14, R19, and R20 in Formulae 1-1 and 1(1) may not be hydrogen.
For example, at least one of R1a, R1e, R2a, R2e, R12, R14, R19, and R20 in Formulae 1-1 and 1(1) may each independently be selected from:
In one or more embodiments, at least one of R14, R19, and R20 in Formulae 1-1 and 1(1) may be a deuterium-containing substituent. The deuterium-containing substituent are the same as described herein.
In one or more embodiments, at least one of R19 and R20 in Formulae 1-1 and 1(1) may be deuterium.
L2 in Formula 1 may be selected from a monodentate ligand and a bidentate ligand.
For example, in Formula 1, L2 may be a monodentate ligand, and L2 may be selected from I−, Br−, Cl−, sulfide, nitrate, azide, hydroxide, cyanate, isocyanate, thiocyanate, water, acetonitrile, pyridine, ammonia, carbon monoxide, P(Ph)3, P(Ph)2CH3, PPh(CH3)2, and P(CH3)3, but embodiments of the present disclosure are not limited thereto.
In one or more embodiments, in Formula 1, L2 may be a bidentate ligand, and L2 may be selected from oxalate, acetylacetonate, a picolinic acid, 1,2-bis(diphenylphosphino)ethane, 1,1-bis(diphenylphosphino)methane, glycinate, and ethylenediamine, but embodiments of the present disclosure are not limited thereto.
In one or more embodiments, L2 in Formula 1 may be selected from ligands represented by Formulae 3A to 3F:
In Formulae 3A to 3F,
In one or more embodiments, L2 in Formula 1 may be represented by one of Formulae 5-1 to 5-119, but embodiments of the present disclosure are not limited thereto:
In Formulae 5-1 to 5-119,
The organometallic compound represented by Formula 1 is neutral and may not have a salt form including an anion and a cation.
The organometallic compound represented by Formula 1 may be selected from Compounds 1 to 9, but embodiments of the present disclosure are not limited thereto:
A maximum emission wavelength of the organometallic compound may be in a range of about 440 nanometers (nm) to about 470 nm (for example, about 440 nm to about 467 nm). When the maximum emission wavelength is in a range of about 440 nm to about 470 nm, an organic light-emitting device emitting deep blue light may be provided.
The organometallic compound represented by Formula 1 essentially includes CY1 and CY2 at positions defined herein.
Thus, the organometallic compound may have a natural population analysis (NPA) charge value of about 0.50 or less, for example, about 0 to about 0.48. The NPA charge value is evaluated by a density functional theory (DFT) method using a Gaussian program that is structurally optimized at a level of B3LYP/6-31G(d,p).
Also, an open fraction value of atom A bonded to R19 in Formula 1 (see Formula 1′) may be about 0.5 or less, for example, about 0.1 to about 0.49.
Formula 1′
The open fraction value is calculated by using Equation 1. Equation 1 will be described below with reference to
Open fraction value=Areascreened/Areafree. Equation 1
In Equation 1,
The atom B means a combination of any atoms that can screen the atom A of Formula 1.
The open fraction value represents how much the atom A is opened in Formula 1. As the open fraction value decreases, the atom A is more screened by another atom B in Formula 1 and is less opened. A bond between the atom A and R19 in Formula 1 is a relatively weak bond that may be easily damaged by heat or the like generated when an organic light-emitting device is stored and/or driven. Since the atom A of Formula 1 has a relatively small open fraction value as described above, that is, since a relatively large portion of the atom A is screened by another atom B of Formula 1, damage to the bond between the atom A and R19 in Formula 1 may be substantially prevented. Thus, the organometallic compound represented by Formula 1 may have robustness.
Since the organometallic compound having the NPA charge value and the open fraction value in the above-described ranges has excellent heat resistance and/or decomposition resistance, an electronic device (for example, an organic light-emitting device) including the organometallic compound may have a long lifespan.
On the other hand, a “carbon atom C” in Formula 1 is essentially bonded to a cyano group (see Formula 1′). Thus, since the organometallic compound represented by Formula 1 has a deep highest occupied molecular orbital (HOMO) energy level (that is, a large absolute value of a HOMO energy level or a low HOMO energy level), the organometallic compound may have a high triplet energy level. Therefore, the use of the organometallic compound represented by Formula 1 may make it possible to emit deep blue light having excellent color purity.
Also, in one or more embodiments, the organometallic compound represented by Formula 1 may include at least one deuterium. For example, at least one of R19 and R20 in Formula 1 may be a deuterium-containing substituent. Compared with a single bond between carbon and hydrogen, a single bond between carbon and deuterium has a strong bond strength and a short bond length. Thus, the deuterium-containing organometallic compound may have higher thermal stability than the deuterium-free organometallic compound. Therefore, radicalization of the organometallic compound represented by Formula 1 slowly progresses due to heat and/or electric field generated when the organic light-emitting device is kept and/or driven, and thus, an organic light-emitting device including the organometallic compound may have a longer lifespan.
Furthermore, in one or more embodiments, R14 in Formula 1 may be a substituent other than hydrogen. For example, R14 in Formula 1 may be a C1-C20 alkyl group or a deuterium-containing substituent. The organometallic compound represented by Formula 1 may have a high lowest unoccupied molecular orbital (LUMO) energy level and a high triplet (Ti) energy level. Thus, the use of the organometallic compound represented by Formula 1 may make it possible to emit blue light having excellent color purity.
Table 1 below shows results obtained when HOMO energy levels, LUMO energy levels, T1 energy levels, and maximum emission wavelengths of some of the organometallic compounds represented by Formula 1 and Compounds E and F were evaluated using a Gaussian 09 program for optimizing a molecular structure through DFT based on B3LYP.
From Table 1, it can be confirmed that Compounds 1 to 9 have relatively high Ti energy levels, as compared with Compounds E and F.
On the other hand, in synthesizing an organometallic compound that is represented by Formula 1 but includes at least one deuterium, if the organometallic compound is not completely deuterated, an organometallic compound in which hydrogen is not substituted with deuterium may also be synthesized. Thus, a composition containing the organometallic compound, which includes the organometallic compound represented by Formula 1 (hereinafter, a “first organometallic compound”) and further includes an organometallic compound represented by Formula 2 (hereinafter, a “second organometallic compound”), may be provided:
In Formulae 1 and 2,
Formula 1 is the same as described herein, and M11, n11, L12, n12, X3, X4, CY3, CY4, R3, R4, R21 to R26, a3, a4, R29, and R30 in Formula 2 are the same as described in connection with M1, n1, L2, n2, X1, X2, CY1, CY2, R1, R2, R11 to R16, a1, a2, R19, and R20 in Formula 1, except that deuterium is not included.
For example, in Formula 2,
A deuteration rate of the composition containing the organometallic compound may be about 50% or more. The deuteration rate may be calculated by using Equation 2:
deuteration rate (%)=nD2/(nH2+nD2)×100. Equation 2
In Equation 2,
When a substituent indicated by a dashed box in Compound 4 is a deuterium-containing substituent, a deuterium-free substituent corresponding to the deuterium-containing substituent in Compound 4′ may mean a substituent indicated by a dashed box in Compound 4′. That is, in the present disclosure, substituents bonded to carbon at the same position in two compounds that differ from each other only in terms of the presence or absence of isotope are defined as “corresponding” substituents.
For example, if the first organometallic compound includes two deuterium-containing substituents, nD2 means the total number of deuterium atoms included in the two deuterium-containing substituents. Also, nH2 means the sum of the number of hydrogens included in the two deuterium-containing substituents and the number of hydrogens included in the deuterium-free substituent of the second organometallic compound corresponding to the two deuterium-containing substituents.
In one or more embodiments, the deuteration rate may be about 70% or more, about 90% or more, about 95% or more, about 96% or more, about 97% or more, about 98% or more, or about 99% or more, but embodiments of the present disclosure are not limited thereto.
Synthesis methods of the organometallic compound represented by Formula 1 may be recognizable by one of ordinary skill in the art by referring to Synthesis Examples provided below. The composition containing the organometallic compound is not the addition of at least one second organometallic compound, but may result from an incomplete deuteration in synthesizing the organometallic compound represented by Formula 1. For example, the composition may include a mixture of Compound 3 and a resultant from an incomplete deuteration of Compound 3 or a mixture of Compound 4 and a resultant from an incomplete deuteration of Compound 4, but embodiments of the present disclosure are not limited thereto.
Synthesis methods of the organometallic compound represented by Formula 1 may be recognizable by one of ordinary skill in the art by referring to Synthesis Examples provided below.
The organometallic compound represented by Formula 1 or the composition containing the organometallic compound may be suitable for use as a dopant in an organic layer of an organic light-emitting device, for example, an emission layer in the organic layer.
According to one or more embodiments, an organic light-emitting device may include:
Since the organic light-emitting device includes the organic layer including the organometallic compound represented by Formula 1 or the composition containing the organometallic compound, the organic light-emitting device may have high efficiency, a long lifespan, and high color purity.
The organometallic compound represented by Formula 1 or the composition containing the organometallic compound may be used between a pair of electrodes of the organic light-emitting device. For example, the organometallic compound represented by Formula 1 or the composition containing the organometallic compound may be included in the emission layer. The organometallic compound or the composition containing the organometallic compound may act as a dopant, and the emission layer may further include a host (that is, an amount of the organometallic compound represented by Formula 1 or the composition containing the organometallic compound is smaller than an amount of the host). In this embodiment, the dopant may emit blue light.
The expression “(an organic layer) includes at least one of organometallic compounds” as used herein may include an embodiment in which “(an organic layer) includes identical organometallic compounds represented by Formula 1” and an embodiment in which “(an organic layer) includes two or more different organometallic compounds represented by Formula 1.”
For example, the organic layer may include, as the organometallic compound, only Compound 1. In this embodiment, Compound 1 may be included in an emission layer of the organic light-emitting device. In one or more embodiments, the organic layer may include, as the organometallic compound, Compound 1 and Compound 2. In these embodiments, Compound 1 and Compound 2 may be included in an identical layer (for example, Compound 1 and Compound 2 all may be included in an emission layer).
The first electrode may be an anode, which is a hole injection electrode, and the second electrode may be a cathode, which is an electron injection electrode; or the first electrode may be a cathode, which is an electron injection electrode, and the second electrode may be an anode, which is a hole injection electrode.
In one or more embodiments, in the organic light-emitting device, the first electrode is an anode, and the second electrode is a cathode, and the organic layer further includes a hole transport region disposed between the first electrode and the emission layer and an electron transport region disposed between the emission layer and the second electrode, wherein the hole transport region includes at least one selected from a hole injection layer, a hole transport layer, and an electron blocking layer, and wherein the electron transport region includes at least one selected from a hole blocking layer, an electron transport layer, and an electron injection layer.
The term “organic layer” as used herein refers to a single layer and/or a plurality of layers between the first electrode and the second electrode of the organic light-emitting device. The “organic layer” may include, in addition to an organic compound, an organometallic complex including metal.
A substrate may be additionally disposed under the first electrode 11 or above the second electrode 19. For use as the substrate, any substrate that is used in general organic light-emitting devices may be used, and the substrate may be a glass substrate or a transparent plastic substrate, each having excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and water resistance.
The first electrode 11 may be formed by depositing or sputtering a material for forming the first electrode 11 on the substrate. The first electrode 11 may be an anode. The material for forming the first electrode 11 may be selected from materials with a high work function to facilitate hole injection. The first electrode 11 may be a reflective electrode, a semi-transmissive electrode, or a transmissive electrode. The material for forming the first electrode 11 may be, for example, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO2), and zinc oxide (ZnO). In one or more embodiments, 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 first electrode 11.
The first electrode 11 may have a single-layered structure or a multi-layered structure including two or more layers. For example, the first electrode 11 may have a three-layered structure of ITO/Ag/ITO, but the structure of the first electrode 110 is not limited thereto.
The organic layer 15 is disposed on the first electrode 11.
The organic layer 15 may include a hole transport region, an emission layer, and an electron transport region.
The hole transport region may be disposed between the first electrode 11 and the emission layer.
The hole transport region may include at least one selected from a hole injection layer, a hole transport layer, an electron blocking layer, and a buffer layer. The hole transport layer may be a single layer or may include two or more layers.
The hole transport region may include only either a hole injection layer or a hole transport layer. In one or more embodiments, the hole transport region may have a hole injection layer/hole transport layer structure, a hole injection layer/hole transport layer/electron blocking layer structure, a hole transport layer/electron blocking layer structure, a hole injection layer/first hole transport layer/second hole transport layer structure, a hole injection layer/first hole transport layer/second hole transport layer/electron blocking layer structure, or a first hole transport layer/second hole transport layer/electron blocking layer structure, in which layers of each structure may be sequentially stacked on the first electrode 11 in this stated order.
A hole injection layer may be formed on the first electrode 11 by using one or more suitable methods selected from 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 Angstroms per second (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 revolutions per minute (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.
Conditions for forming a hole transport layer and an electron blocking layer may be understood by referring to conditions for forming the hole injection layer.
The hole transport region may include at least one selected from 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/dodecylbenzene sulfonic acid (PANI/DBSA), poly(3,4-ethylenedioxythiophene)/poly(4-styrene sulfonate) (PEDOT/PSS), polyaniline/camphor sulfonic acid (PANI/CSA), polyaniline/poly(4-styrene sulfonate) (PANI/PSS), a compound represented by Formula 201 below, and a compound represented by Formula 202 below:
Ar101 and Ar102 in Formula 201 may each independently be selected from:
In Formula 201, xa and xb may each independently be an integer from 0 to 5, or 0, 1, or 2. For example, xa is 1 and xb is 0, but xa and xb are not limited thereto.
R101 to R108, R111 to R119, and R121 to R124 in Formulae 201 and 202 may each independently be selected from:
R109 in Formula 201 may be selected from:
According to an embodiment, the compound represented by Formula 201 may be represented by Formula 201A, but embodiments of the present disclosure are not limited thereto:
R101, R111, R112, and R109 in Formula 201A may be understood by referring to the description provided herein.
For example, the compound represented by Formula 201 and the compound represented by Formula 202 may include compounds HT1 to HT20 illustrated below, but embodiments of the present disclosure are not limited thereto.
A thickness of the hole transport region may be in a range of about 100 Angstroms (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, the thickness of the hole injection layer may be in a range of about 100 Å to about 10,000 Å, and for example, about 100 Å to about 1,000 Å, and the thickness of the hole transport layer may be in a range of about 50 Å to about 2,000 Å, and for example, about 100 Å to about 1,500 Å. While not wishing to be bound by theory, it is understood that 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 improving 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 present disclosure are not limited thereto. Non-limiting examples of the p-dopant are a quinone derivative, such as tetracyanoquinonedimethane (TCNQ) or 2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinonedimethane (F4-TCNQ); a metal oxide, such as a tungsten oxide or a molybdenum oxide; and a cyano group-containing compound, such as Compound HT-D1 or Compound HT-D2 below, but embodiments of the present disclosure are not limited thereto.
The hole transport region may include a buffer layer.
Also, 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 a formed organic light-emitting device may be improved.
Then, an emission layer may be formed on the hole transport region by vacuum deposition, spin coating, casting, LB deposition, or the like. When the emission layer is formed by vacuum deposition or spin coating, the deposition or coating conditions may be similar to those applied to form the hole injection layer although the deposition or coating conditions may vary according to the material that is used to form the emission layer.
Meanwhile, 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 emission layer may include a host and a dopant, and the dopant may include the organometallic compound represented by Formula 1 or a composition containing the organometallic compound.
The host may include at least one selected from TPBi, TBADN, ADN (also referred to as “DNA”), CBP, CDBP, TCP, mCP, Compound H50, and Compound H51:
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 stack structure including a red emission layer, a green emission layer, and/or a blue emission layer, the emission layer may emit white light.
When the emission layer includes a host and a dopant, an amount of the dopant may be in a range of about 0.01 parts by weight to about 15 parts by weight based on 100 parts by weight of the host, but embodiments of the present disclosure are not limited thereto.
The dopant may include at least one of organometallic compounds represented by Formula 1 or a composition containing the organometallic compound.
A thickness of the emission layer may be in a range of about 100 Å to about 1,000 Å, for example, about 200 Å to about 600 Å. While not wishing to be bound by theory, it is understood that when the thickness of the emission layer is within this range, excellent light-emission characteristics may be obtained without a substantial increase in driving voltage.
Then, an electron transport region may be disposed on the emission layer.
The electron transport region may include at least one selected from a hole blocking layer, an electron transport layer, and an electron injection layer.
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, but 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 BAIq but embodiments of the present 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. While not wishing to be bound by theory, it is understood that when the thickness of the hole blocking layer is within these ranges, the hole blocking layer may have improved hole blocking ability without a substantial increase in driving voltage.
The electron transport layer may include at least one selected from BCP, Bphen, Alq3, BAIq, TAZ, and NTAZ.
In one or more embodiments, the electron transport layer may include at least one of ET1 to ET19, but embodiments of the present disclosure are not limited thereto:
A thickness of the electron transport layer may be in a range of about 100 Å to about 1,000 Å, for example, about 150 Å to about 500 Å. While not wishing to be bound by theory, it is understood that when the thickness of the electron transport layer is within the range described above, the electron transport layer may have satisfactory electron transport characteristics without a substantial increase in driving voltage.
Also, the electron transport layer may further include, in addition to the materials described above, a metal-containing material.
The metal-containing material may include a Li complex. The Li complex may include, for example, Compound ET-D1 (lithium 8-hydroxyquinolate, LiQ) or ET-D2.
The electron transport region may include an electron injection layer that promotes flow of electrons from the second electrode 19 thereinto.
The electron injection layer may include at least one selected from LiF, NaCl, CsF, Li2O, and BaO.
A thickness of the electron injection layer may be in a range of about 1 Å to about 100 Å, for example, about 3 Å to about 90 Å. While not wishing to be bound by theory, it is understood that when the thickness of the electron injection layer is within the range described above, the electron injection layer may have satisfactory electron injection characteristics without a substantial increase in driving voltage.
The second electrode 19 is disposed on the organic layer 15. The second electrode 19 may be a cathode. A material for forming the second electrode 19 may be selected from metal, an alloy, an electrically conductive compound, and a combination thereof, which have 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 a material for forming the second electrode 19. In one or more embodiments, to manufacture a top-emission type light-emitting device, a transmissive electrode formed using ITO or IZO may be used as the second electrode 19.
Hereinbefore, the organic light-emitting device has been described with reference to
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 iso-amyl 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” as used herein refers to a monovalent group represented by —OA101 (wherein A101 is the C1-C60 alkyl group), and non-limiting 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 including 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 including 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 non-limiting 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 saturated 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 non-limiting 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 hydrocarbon 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 a C6-C60 arylene group as used herein refers to a divalent group having a carbocyclic aromatic system having 6 to 60 carbon atoms. Non-limiting 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 term “C1-C60 heteroaryl group” as used herein refers to a monovalent group having a heterocyclic 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 heterocyclic 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. Non-limiting 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 C1-C60 heteroaryl group and the C1-C60 heteroarylene group each include two or more rings, the rings may be fused to each other.
The term “C6-C60 aryloxy group” as used herein indicates —OA102 (wherein A102 is the C6-C60 aryl group), a C6-C60 arylthio group as used herein indicates —SA103 (wherein A103 is the C6-C60 aryl group), and the term “C7-C60 arylalkyl group” as used herein indicates —A104A105 (wherein A104 is the C6-C59 aryl group and A105 is the C1-C53 alkyl group).
The term “C1-C60 heteroaryloxy group” as used herein refers to —OA106 (wherein A106 is the C1-C60 heteroaryl group), and the term “C1-C60 heteroarylthio group” as used herein indicates —SA107 (wherein A107 is the C1-C60 heteroaryl group).
The term “C2-C60 heteroarylalkyl group” as used herein refers to —A108A109 (A109 is a C1-C59 heteroaryl group, and A108 is a C1-C59 alkylene 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.
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 to 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. Non-limiting 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.
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 term “C5-C30 carbocyclic group” as used herein refers to a monocyclic group or a polycyclic group, and, according to its chemical structure, a monovalent, divalent, trivalent, tetravalent, pentavalent, or hexavalent group.
The term “C2-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 2 to 30 carbon atoms. The term “C2-C30 heterocyclic group” as used herein refers to a monocyclic group or a polycyclic group, and, according to its chemical structure, a monovalent, divalent, trivalent, tetravalent, pentavalent, or hexavalent group.
At least one substituent of the substituted C5-C30 carbocyclic group, substituted C2-C30 heterocyclic group, substituted C1-C60 alkyl group, substituted C2-C60 alkenyl group, substituted C2-C60 alkynyl group, substituted C1-C60 alkoxy group, substituted C3-C10 cycloalkyl group, substituted C1-C10 heterocycloalkyl group, substituted C3-C10 cycloalkenyl group, substituted C1-C10 heterocycloalkenyl group, substituted C6-C60 aryl group, substituted C6-C60 aryloxy group, substituted C6-C60 arylthio group, substituted C7-C60 arylalkyl group, substituted C1-C60 heteroaryl group, substituted C1-C60 heteroaryloxy group, substituted C1-C60 heteroarylthio group, substituted C2-C60 heteroarylalkyl group, substituted monovalent non-aromatic condensed polycyclic group, and substituted monovalent non-aromatic condensed heteropolycyclic group may be selected from:
When a group containing a specified number of carbon atoms is substituted with any of the groups listed in the preceding paragraph, the number of carbon atoms in the resulting “substituted” group is defined as the sum of the carbon atoms contained in the original (unsubstituted) group and the carbon atoms (if any) contained in the substituent. For example, when the term “substituted C1-C30 alkyl” refers to a C1-C30 alkyl group substituted with C6-C30 aryl group, the total number of carbon atoms in the resulting aryl substituted alkyl group is C7-C60.
Hereinafter, a compound and an organic light-emitting device according to embodiments are described in detail with reference to 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.
3.29 mmol of Ir(acac)3, 16.47 mmol of Ligand 1, and glycerol were added to a reaction vessel, and the mixture was refluxed for 12 hours in a nitrogen atmosphere. After the reaction was completed, the resultant mixture was cooled to room temperature, and the organic layer was separated by adding dichloromethane and distilled water. The organic layer was washed twice with distilled water, dried by using MgSO4, and a solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography (eluent: dichloromethane and n-hexane) to obtain 0.51 mmol of Compound 1. The structure and purity (99% or more) of Compound 1 were identified by using NMR, HPLC, and LCMS.
1H-NMR (300 MHz, CD2Cl2) δ 7.8 (1H, t), 7.7-7.55 (2H, m), 7.1-6.7 (10.5H, m), 6.6 (1H, s), 6.55-6.4 (2H, m).
0.50 mmol of Compound 2 was synthesized in the same manner as in Synthesis Example 1, except that Ligand 2 was used instead of Ligand 1. The structure and purity (99% or more) of Compound 2 were identified by using NMR, HPLC, and LCMS.
1H-NMR (300 MHz, CD2Cl2) δ 7.50 (1H, s), 7.45 (1H, s), 7.15-6.88 (3H, m), 6.86-6.84 (3H, m), 6.82-6.72 (5H, m), 6.68 (1H, s), 6.46-6.42 (2H, m), 5.46 (1H, s), 2.59 (3H, s)
14 mmol (5.5 g) of Intermediate 3, 14 mmol of 3-cyano-phenylboronic acid, 0.45 mmol (0.52 g) of tetrakis-(triphenylphosphine)palladium(0), and 45 mmol (6.21 g) of potassium carbonate were mixed with 120 ml of a mixture of 1,4-dioxane and water (volume ratio: 3:1), and the mixture was refluxed at a temperature of 120° C. for overnight. The reaction mixture was cooled, and the product was extracted with ethyl acetate and water. The organic layer was washed three times with water, dried by using magnesium sulfate, and the solvent was removed under reduced pressure. The crude product obtained therefrom was purified by silica gel column chromatography (eluent: dichloromethane and hexane), thereby obtaining 7 mmol (3.0 g) of Ligand 3.
The structure and purity (99.73% or more) of Ligand 3 were identified by using NMR, HPLC, and LCMS. As a result of NMR analysis, it was identified that a deuterium substitution rate was 79% or more.
1H-NMR (300 MHz, CD2Cl2) δ 7.7 (0.11H, s), 7.6 (1H, m), 7.7-7.2 (3H, m), 6.99 (0.11H, s), 6.9 (2H, s), 6.8 (0.1H, s)
0.55 mmol of Compound 3 was synthesized in the same manner as in Synthesis Example 1, except that Ligand 3 was used instead of Ligand 1. The structure and purity (99% or more) of Compound 3 were identified by using NMR, HPLC, and LCMS.
1H-NMR (300 MHz, CD2Cl2) δ 7.80 (0.10H, s), 7.70 (0.08H, s), 7.50 (0.08H, s), 7.10 (0.13H, 7.00 (1H, s), 6.91 (0.10H, s), 6.88 (0.24H, t), 6.85 (1H, s), 6.80-6.75 (0.24H, m), 6.60 (1H, s), 6.50 (0.18H, s), 6.40 (1H, d), 5.45 (0.24H, s)
Ligand 4 was synthesized in the same manner as in Synthesis of Ligand 3 in Synthesis Example 3, except that Intermediate 4 was used instead of Intermediate 3. The structure and deuterium substitution rate of Ligand 4 were identified by using NMR, HPLC, and LCMS.
1H-NMR (300 MHz, CD2Cl2) δ 7.5 (0.36H, d), 7.4-7.1 (1.33H, m), 7-6.7 (1H, m), 2.5 (0.16H, s)
0.53 mmol of Compound 4 was synthesized in the same manner as in Synthesis Example 1, except that Ligand 4 was used instead of Ligand 1. The structure and purity (99% or more) of Compound 4 were identified by using NMR, HPLC, and LCMS.
1H-NMR (300 MHz, CD2Cl2) δ 7.47 (0.1H, s), 7.38 (0.1H, s), 7.10-6.65 (4.2H, m), 6.46 (1H, m), 5.5 (0.2H, s), 2.57 (0.39H, s)
0.50 mmol of Compound 5 was synthesized in the same manner as in Synthesis Example 1, except that Ligand 5 was used instead of Ligand 1. The structure and purity (99% or more) of Compound 5 were identified by using NMR, HPLC, and LCMS.
1H-NMR (300 MHz, CD2Cl2) δ 7.50 (1H, s), 7.45 (1H, s), 7.2-6.8 (11.2H, m), 6.7-6.6 (3H, m), 5.46 (1H, s), 3.2 (1H, m), 1.4 (6H, d)
0.51 mmol of Compound 6 was synthesized in the same manner as in Synthesis Example 1, except that Ligand 6 was used instead of Ligand 1. The structure and purity (99% or more) of Compound 6 were identified by using NMR, HPLC, and LCMS.
1H-NMR (300 MHz, CD2Cl2) δ 7.65 (1H, s), 7.56 (1H, s), 7.2-7.0 (3H, m), 6.9-6.6 (8H, m), 5.4 (1H, s), 1.47 (9H, s)
0.53 mmol of Compound 7 was synthesized in the same manner as in Synthesis Example 1, except that Ligand 7 was used instead of Ligand 1. The structure and purity (99% or more) of Compound 7 were identified by using NMR, HPLC, and LCMS.
1H-NMR (300 MHz, CD2Cl2) δ 7.50 (1H, s), 7.45 (1H, s), 7.15-6.88 (3H, m), 6.86-6.84 (3H, m), 6.82-6.72 (5H, m), 6.68 (1H, s), 6.46-6.42 (2H, m), 5.46 (1H, s), 2.60 (3H, s)
0.48 mmol of Compound 8 was synthesized in the same manner as in Synthesis Example 1, except that Ligand 8 was used instead of Ligand 1. The structure and purity (99% or more) of Compound 8 were identified by using NMR, HPLC, and LCMS.
1H-NMR (300 MHz, CD2Cl2) δ 7.8 (1H, s), 7.7 (2H, d), 7.6-7.5 (2H, m), 7.5-7.4 (1H, m), 7.1-7.0 (3H, t), 7.0-6.9 (5H, m), 6.9-6.8 (4H, m), 6.55 (1H, s), 6.5-6.4 (1H, m), 5.5 (1H, s)
0.5 mmol of Compound 9 was synthesized in the same manner as in Synthesis Example 1, except that Ligand 9 was used instead of Ligand 1. The structure and purity (99% or more) of Compound 9 were identified by using NMR, HPLC, and LCMS.
1H-NMR (300 MHz, CD2Cl2) δ 7.50-7.45 (2H, d), 7.15-6.9 (3H, m), 6.85-6.7 (5H, m), 6.7-6.65 (2H, m), 6.6 (1H, s), 6.4 (2H, s), 5.5 (1H, s), 2.6 (3H, s), 2.2 (3H, s)
The HOMO energy levels, LUMO energy levels, and T1 energy levels of Compounds 1 to 9, E, and F were evaluated using the methods provided in Table 2.
Results thereof are shown in Table 3.
It can be confirmed from Table 3 that Compounds 1 to 9 have electrical characteristics suitable for use as materials for an organic light-emitting device. For example, it can be confirmed that Compounds 1 to 9 have relatively higher triplet energy levels than Compounds E and F.
Light emission characteristics of each Compound were evaluated by evaluating PL spectra of Compounds 1 to 9, E, and F. Compound 1 was diluted with CHCl3 to a concentration of 10 millimolar (mM), and a PL spectrum was measured at room temperature by using ISC PC1 Spectrofluorometer with a xenon lamp. This process was repeated on Compounds 2 to 9, E, and F.
Maximum wavelengths of the PL spectra of Compounds 1 to 9, E, and F are shown in Table 4.
Referring to Table 4, compounds (Compounds 1 to 9), in which a cyano group is substituted at a para-position with respect to an Ir-carbon bond (Compound 1 to 9), exhibit a maximum emission wavelength of 470 nanometers (nm) or less (for example, 466 nm or less). On the other hand, compounds (Compounds E and F), in which a cyano group is not substituted at a para-position with respect to an Ir-carbon bond, exhibit a maximum emission wavelength greater than 470 nm. It can be seen from these results that deep blue light emission is provided when the cyano group is substituted at the para-position with respect to the Ir-carbon bond. It can be confirmed from Table 4 that Compounds 1 to 9 have excellent light emission characteristics.
The NPA charge values of Compounds 1 to 9 and A to F were evaluated by using a DFT method of a Gaussian program that was structurally optimized at a level of B3LYP/6-31G(d,p). Results thereof are shown in Table 5 below. Also, the open fraction value of an atom A of each of Compounds 1 to 9 and A to F (the position of the atom A of each Compound refers to the position of the atom A marked in Compound 1) was evaluated based on Equation 1. Results thereof are shown in Table 5.
Referring to Table 5, it can be confirmed that Compounds 1 to 9 have relatively small NPA charge values and open fraction values at the same time, as compared with Compounds A to F.
A glass substrate, on which an ITO electrode (first electrode, anode) having a thickness of 1,500 Å was formed, was sonicated with distilled water. After the sonicating with distilled water was completed, the glass substrate was ultrasonically cleaned by sequentially using isopropyl alcohol, acetone, and methanol, was dried, and then transferred to a plasma cleaner. Then, the glass substrate was cleaned for 5 minutes by using oxygen plasma and was provided to a vacuum deposition apparatus.
Compound HT3 was vacuum-deposited on the ITO electrode of the glass substrate to form a first hole injection layer having a thickness of 3,500 Å, Compound HT-D1 was vacuum-deposited on the first hole injection layer to form a second hole injection layer having a thickness of 300 Å, and TAPC was vacuum-deposited on the second hole injection layer to form an electron blocking layer having a thickness of 100 Å, thereby forming a hole transport region.
mCP (host) and Compound 1 (dopant, 7 wt %) were co-deposited on the hole transport region to form an emission layer having a thickness of 300 Å.
Compound ET3 was vacuum-deposited on the emission layer to form an electron transport layer having a thickness of 250 Å, ET-D1 (LiQ) was deposited on the electron transport layer to form an electron injection layer having a thickness of 5 Å, and Al was deposited on the electron injection layer to form a second electrode (cathode) having a thickness of 1,000 Å, thereby completing the manufacture of an organic light-emitting device.
Organic light-emitting devices of Examples 2 to 9 and Comparative Examples 1 to 4 were manufactured in the same manner as in Example 1, except that Compounds shown in Table 6 were each used instead of Compound 1 as a dopant in forming an emission layer.
An EL spectrum, a change in current density according to voltage, a change in luminance according to voltage, conversion efficiency, lifespan, and CIE color coordinates were measured with respect to the organic light-emitting devices manufactured according to Examples 1 to 9 and Comparative Examples 1 to 4. Specific measurement methods are as follows, and results thereof are shown in Table 6.
(1) Measurement of EL Spectrum
The EL spectra of the manufactured organic light-emitting devices were measured by using a luminance meter (Minolta Cs-1000A) at a luminance of 500 candelas per square meter (cd/m2).
(2) Measurement of Change in Current Density According to Voltage
A current value flowing through the manufactured organic light-emitting devices was measured by using a current-voltage meter (Keithley 2400) with respect to the manufactured organic light-emitting devices while increasing a voltage from 0 volts (V) to 10 V, and a current density was obtained by dividing the measured current value by an area.
(3) Measurement of Change in Luminance According to Voltage
Luminance was measured by using a luminance meter (Minolta Cs-1000A) with respect to the manufactured organic light-emitting devices while increasing a voltage from 0 V to 10 V.
(4) Measurement of Conversion Efficiency
Current efficiency (cd/A) of the same current density (10 milliamperes per square centimeter, mA/cm2) was calculated by using the luminance and the current density measured from (2) and (3) and the voltage. Then, conversion efficiency was calculated by dividing the current efficiency by a y value of CIE color coordinates measured in (6).
(5) Measurement of Lifespan
An amount of time (T95) that lapsed when luminance measured from (3) was 95% (T95) of initial luminance (100%) was calculated.
(6) Measurement of CIE Color Coordinates
CIE color coordinates were obtained by measuring EL spectra of the manufactured organic light-emitting devices at a luminance of 500 candelas per square meter (cd/m2) by using a luminance meter (Minolta Cs-1000A).
Efficiency*, T95*: Relative values of efficiency and T95 with respect to those of
From Table 6, it can be confirmed that the organic light-emitting devices of Examples 1 to 9 emit deep blue light having excellent color purity and have remarkably improved lifespan characteristics, as compared with the organic light-emitting devices of Comparative Examples 1 to 4.
The organometallic compound according to embodiments has excellent electrical characteristics and thermal stability. Accordingly, an organic light-emitting device including the organometallic compound may have excellent driving voltage, current density, efficiency, power, color purity, and lifespan characteristics.
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 of the present disclosure as defined by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2017-0004165 | Jan 2017 | KR | national |
