Multiple host materials and organic electroluminescent devices containing them

Abstract

To provide an organic electroluminescent device that can exhibit excellent life characteristics while maintaining high luminous efficiency.SOLUTION: A plurality of host materials include at least one first host compound and at least one second host compound, wherein the first host compound is represented by the following formula 2, and the second host compound is represented by a specific formula.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a plurality of host materials and an organic electroluminescent device containing the same. [Background technology]

[0002] Electroluminescent devices (EL devices) are self-emissive display devices that offer advantages such as wider viewing angles, higher contrast ratios, and faster response times. The first organic EL device was developed in 1987 by Eastman Kodak using small aromatic diamine molecules and aluminum complexes as materials to form the emissive layer (see Appl. Phys. Lett. 51, 913, 1987).

[0003] Organic light-emitting diode (OLED) devices convert electrical energy into light by applying electricity to an organic electroluminescent material, and typically include an anode, a cathode, and an organic layer formed between the two electrodes. The organic layers of an OLED device may include a hole injection layer, a hole transport layer, an electron blocking layer, an emissive layer (containing a host material and a dopant material), an electron buffer layer, an electron blocking layer, an electron transport layer, an electron injection layer, etc. The materials used in the organic layers can be classified according to their function into hole injection materials, hole transport materials, electron blocking materials, emissive materials, electron buffer materials, hole blocking materials, electron transport materials, electron injection materials, etc. In an OLED device, when a voltage is applied, holes from the anode and electrons from the cathode are injected into the emissive layer, and high-energy excitons are generated by the recombination of holes and electrons. When an organic light-emitting compound returns from an excited state to a ground state, it transitions to an excited state due to energy, and emits light from that energy.

[0004] The most important factor determining the luminous efficiency in organic EL devices is the light-emitting material. Light-emitting materials are required to have high quantum efficiency, high electron and hole mobility, and uniformity and stability of the formed light-emitting layer. Light-emitting materials are classified by emission color into blue, green, and red light-emitting materials, and further include yellow or orange light-emitting materials. Furthermore, light-emitting materials are classified functionally into host materials and dopant materials. In recent years, an urgent challenge has been the development of organic EL devices with high efficiency and long lifespan. In particular, considering the EL properties required for medium and large OLED panels, the development of significantly superior light-emitting materials that surpass conventional materials is urgently needed. For this purpose, preferably, the host material, as a solid-state solvent and energy transmitter, should have high purity and a suitable molecular weight for deposition under vacuum. Furthermore, the host material is required to have high glass transition and thermal decomposition temperatures to achieve thermal stability, high electrochemical stability to achieve a long lifespan, easy formability of amorphous thin films, good adhesion to adjacent layers, and no interlayer movement.

[0005] By using luminescent materials as a combination of host and dopant, color purity, luminous efficiency, and stability can be improved. Generally, EL devices with superior properties have a structure that includes a luminescent layer formed by doping a host with a dopant. When using such a dopant / host material system as a luminescent material, the host material has a significant impact on the efficiency and lifespan of the EL device, so their selection is important.

[0006] Japanese Patent Publication No. 2001-23777 discloses an organic electroluminescent device that uses a compound in which a nitrogen-containing five-membered heteroaryl is condensed at an intermediate benzene ring of a phenanthrene skeleton as a host material. The organic electroluminescent device containing the compound disclosed in the above document exhibits excellent blue color purity characteristics. However, the above document does not disclose the mixed structure of the phosphorescent layer, and further improvements in driving voltage, current efficiency, and driving life are needed. [Overview of the Initiative]

Problems to be Solved by the Invention

[0007] An object of the present disclosure is to provide an organic electroluminescent device having a long lifespan while maintaining high luminous efficiency.

Means for Solving the Problems

[0008] As a result of intensive research to solve the above technical problems, the inventor of the present invention has found that the above object can be achieved by a plurality of host materials including at least one first host compound represented by the following formula 1 or 2 and at least one second host compound represented by the following formula 3, and thus completed the present invention.

Chemical Formula

Chemical formula

[0009] Advantageous effects of the invention The phenanthroxazole and phenanthrothiazole compounds according to this disclosure inherently possess high electronegativity and electron-rich groups, and have rigid properties as structures in which phenanthrene and oxazole, or phenanthrene and thiazole, are condensed, thereby promoting intermolecular charge transitions. Furthermore, when such intermolecular stacking is enhanced, the introduction of horizontal molecular orientation becomes easier, thereby enabling the introduction of fast electron current characteristics. Therefore, by using a limited number of structures such as triazine and pyrimidine derivatives as luminescent materials, it is possible to provide organic electroluminescent devices that exhibit relatively low driving voltages by improving interfacial properties such as current efficiency, power efficiency, and high purity color, as well as excellent luminescence efficiency, while maintaining the intermolecular stacking effect together with the electron transport layer.

[0010] Furthermore, when using a light-emitting material that mixes a hole-type amine substituted with a phenanthroxazole compound and a phenanthrothiazole compound as a first host with an electron-type azine material substituted with a phenanthroxazole compound and a phenanthrothiazole compound as a second host, it is possible to introduce organic electroluminescent devices with high efficiency, long lifetime, and fast drive voltage. Generally, when phosphorescent materials are substituted with other substituents such as carbazole-type derivatives with high dihedral angles, the drive voltage increases and efficiency decreases due to the interruption of electron current. However, when using the light-emitting compounds according to this disclosure, it is possible to improve the interface properties by fast current injection characteristics and by improving intermolecular stacking and interactions, thereby producing organic electroluminescent devices with current efficiency, power efficiency, and high purity color, as well as relatively low drive voltage and excellent luminescence efficiency. [Brief explanation of the drawing]

[0011] [Figure 1] The current efficiency based on brightness of the organic electroluminescent devices manufactured in Comparative Example 2 and Device Example 1 is shown. [Modes for carrying out the invention]

[0012] The following provides a detailed description of this disclosure. However, the following description is intended to illustrate the disclosure and is not intended to limit its scope.

[0013] Organic electroluminescent devices containing organic electroluminescent compounds represented by formulas 1, 2, or 3 above are described in more detail below.

[0014] In equations 1 and 2 above, X1 represents -N=, -NR7-, -O-, or -S-, and Y1 represents -N=, -NR8-, -O-, or -S-, except that when X1 represents -N=, Y1 represents -NR8-, -O-, or -S-, and when X1 represents -NR7-, Y1 represents -N=, -O-, or -S-. According to one embodiment of the present disclosure, one of X1 and Y1 can be -N=, and the other can be -NR7-, -O-, or -S-. Furthermore, according to another embodiment of the present disclosure, one of X1 and Y1 can be -N=, and the other can be -O- or -S-. Here, both X1 and Y1 cannot represent -O- or -S-, and when either X1 or Y1 can be -O-, the other cannot be -S-. For example, X1 can be -N= and Y1 can be -O-, X1 can be -O- and Y1 can be -N=, or X1 can be -S- and Y1 can be -N=.

[0015] In formulas 1 and 2 above, R1 represents a substituted or unsubstituted (C6-C30) aryl, or a substituted or unsubstituted (3-30 member) heteroaryl, preferably a substituted or unsubstituted (C6-C30) aryl, or a substituted or unsubstituted (5-25 member) heteroaryl, more preferably a substituted or unsubstituted (C6-C30) aryl, or a substituted or unsubstituted (5-20 member) heteroaryl, such as unsubstituted phenyl, unsubstituted biphenyl, unsubstituted naphthyl, methyl-substituted fluorenyl, methyl-substituted benzofluorenyl, unsubstituted dibenzofuranyl, unsubstituted dibenzothiophenyl, spiro[fluoren-fluoren]yl, or spiro[fluoren-benzofluoren]yl.

[0016] In formulas 1 and 2 above, R2 to R6 are independently hydrogen, deuterium, halogen, cyano, substituted or unsubstituted (C1 to C30) alkyl, substituted or unsubstituted (C6 to C30) aryl, substituted or unsubstituted (3 to 30 member) heteroaryl, substituted or unsubstituted (C3 to C30) cycloalkyl, substituted or unsubstituted (C1 to C30) alkoxy, substituted or unsubstituted tri(C1 to C30) alkylsilyl, substituted or unsubstituted di(C1 to C30) alkyl(C6 to C30) arylsilyl, substituted or unsubstituted (C1 to C30) alkyldi(C6 to C3 0) Represents an arylsilyl, substituted or unsubstituted tri(C6~C30)arylsilyl, substituted or unsubstituted mono- or di-(C1~C30)alkylamino, substituted or unsubstituted mono- or di-(C6~C30)arylamino, or a substituted or unsubstituted (C1~C30)alkyl(C6~C30)arylamino, or can be bonded with adjacent substituents to form a substituted or unsubstituted (C3~C30) monocyclic or polycyclic, alicyclic, or aromatic ring, where these carbon atoms are at least one heterophosphate selected from nitrogen, oxygen, and sulfur. They may be replaced by carbon atoms, preferably independently representing hydrogen, a substituted or unsubstituted (C6-C25) aryl, a substituted or unsubstituted (3-25 member) heteroaryl, a substituted or unsubstituted mono- or di-(C6-C25) arylamino, or bonded with adjacent substituents to form a substituted or unsubstituted (C3-C25) monocyclic or polycyclic, alicyclic, or aromatic ring, where these carbon atoms may be replaced by at least one heteroatom selected from nitrogen, oxygen, and sulfur, more preferably independently These can represent hydrogen, a substituted or unsubstituted (C6-C20) aryl, a substituted or unsubstituted (5-25 member) heteroaryl, or a substituted or unsubstituted di(C6-C18) arylamino, or bond with adjacent substituents to form a substituted or unsubstituted (C3-C25) monocyclic or polycyclic, alicyclic, or aromatic ring, where these carbon atoms may be replaced by at least one heteroatom selected from nitrogen and oxygen, and the heteroaryl may contain at least one heteroatom selected from B, N, O, S, Si, and P.For example, R5 and R6 can each independently be a substituted or unsubstituted phenyl, a substituted or unsubstituted m-biphenyl, a substituted or unsubstituted p-biphenyl, a substituted or unsubstituted fluorenyl, a substituted or unsubstituted naphthyl, a substituted or unsubstituted phenantrenyl, or a substituted or unsubstituted benzofluorenyl.

[0017] In formulas 1 and 2 above, a represents 1 or 2, preferably 1; b and c each independently represent 1 or 2, preferably 1; and d and e each independently represent an integer from 1 to 4, preferably 1 or 2.

[0018] In formulas 1 and 2 above, L1 represents a single bond, substituted or unsubstituted (C6-C30) arylene, or substituted or unsubstituted (3-30 member) heteroarylene, preferably a single bond, or substituted or unsubstituted (C6-C18) arylene, more preferably a single bond, or unsubstituted (C6-C12) arylene, which can be, for example, a single bond, or unsubstituted phenylene.

[0019] A compound represented by formula 1 or 2 can be represented by any one of the following formulas 1-1 to 1-5: [ka]

[0020] In equations 1-1 to 1-5 above, R1 to R6, L1 and a to e are as defined in equations 1 and 2.

[0021] In equation 3 above, X 11 -N=, -NR 17 -, -O- or -S- represents Y 11 -N=, -NR 18 - represents -O- or -S-, however X 11 When -N= represents Y 11 -NR 18 -, -O- or -S- represents X 11 ga-NR 17 When representing -, Y 11represents -N=, -O-, or -S-. According to one embodiment of the present disclosure, X 11 and Y 11 One of them can be -N= and the other can be -NR 17 It can be -, -O-, or -S-. Furthermore, according to another embodiment of the present disclosure, X 11 and Y 11 One of them can be -N=, and the other can be -O- or -S-. Here, X 11 and Y 11 Both X1 and Y1 cannot represent -O- or -S-, and if either X1 or Y1 can be -O-, the other cannot be -S-.

[0022] In equation 3 above, R 11 This represents a substituted or unsubstituted (C6-C30) aryl, or a substituted or unsubstituted (3-30 member) heteroaryl, preferably a substituted or unsubstituted (C6-C30) aryl, or a substituted or unsubstituted (5-25 member) heteroaryl, more preferably a substituted or unsubstituted (C6-C30) aryl, or a substituted or unsubstituted (5-20 member) heteroaryl, and can be, for example, unsubstituted phenyl, unsubstituted biphenyl, unsubstituted naphthyl, methyl-substituted fluorenyl, substituted or unsubstituted carbazolyl, methyl-substituted benzofluorenyl, unsubstituted dibenzofuranyl, unsubstituted dibenzothiophenyl, unsubstituted benzonaphthofuranil, spiro[fluoren-fluoren]yl, or spiro[fluoren-benzofluoren]yl.

[0023] In equation 3 above, R 12 ~R 18Each of these independently consists of hydrogen, deuterium, halogen, cyano, substituted or unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C6-C30) aryl, substituted or unsubstituted (3-30 member) heteroaryl, substituted or unsubstituted (C3-C30) cycloalkyl, substituted or unsubstituted (C1-C30) alkoxy, substituted or unsubstituted tri(C1-C30) alkylsilyl, substituted or unsubstituted di(C1-C30) alkyl(C6-C30) arylsilyl, substituted or unsubstituted (C1-C30) alkyldi(C6-C30) arylsilyl, and substituted Alternatively, they may represent an unsubstituted tri(C6-C30)arylsilyl, a substituted or unsubstituted mono- or di-(C1-C30)alkylamino, a substituted or unsubstituted mono- or di-(C6-C30)arylamino, or a substituted or unsubstituted (C1-C30)alkyl(C6-C30)arylamino, or they may bond with adjacent substituents to form a substituted or unsubstituted (C3-C30) monocyclic or polycyclic, alicyclic, or aromatic ring, where these carbon atoms are replaced by at least one heteroatom selected from nitrogen, oxygen, and sulfur. These atoms may, preferably independently, represent hydrogen, a substituted or unsubstituted (C6-C25) aryl, a substituted or unsubstituted (3-25 member) heteroaryl, a substituted or unsubstituted mono- or di-(C6-C25) arylamino, or, in combination with adjacent substituents, form a substituted or unsubstituted (C3-C25) monocyclic or polycyclic, alicyclic, or aromatic ring, where these carbon atoms may be replaced by at least one heteroatom selected from nitrogen, oxygen, and sulfur, and more preferably independently These can represent hydrogen, a substituted or unsubstituted (C6-C20) aryl, a substituted or unsubstituted (5-25 member) heteroaryl, or a substituted or unsubstituted di(C6-C18) arylamino, or bond with adjacent substituents to form a substituted or unsubstituted (C3-C25) monocyclic or polycyclic, alicyclic, or aromatic ring, where these carbon atoms may be replaced by at least one heteroatom selected from nitrogen and sulfur, and the heteroaryl contains at least one heteroatom selected from B, N, O, S, Si, and P. For example, R 15 and R 16Each of these may be independently selected from the group consisting of substituted or unsubstituted phenyl, substituted or unsubstituted o-biphenyl, substituted or unsubstituted m-biphenyl, substituted or unsubstituted p-biphenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted fluorenyl, substituted or unsubstituted carbazolyl, substituted or unsubstituted dibenzothiophenyl, substituted or unsubstituted benzofluorenyl, substituted or unsubstituted benzocarbazole, and substituted or unsubstituted benzonaphthothiophene.

[0024] In the above formula 3, a' represents 1 or 2, preferably 1; b' and c' each independently represent 1 or 2, preferably 1; and d' represents an integer from 1 to 4, preferably 1 or 2.

[0025] In equation 3 above, X represents either N or CH.

[0026] In the above formula 3, L2 represents a single-bonded, substituted or unsubstituted (C6-C30) arylene, or a substituted or unsubstituted (3-30 member) heteroarylene, preferably a single-bonded, substituted or unsubstituted (C6-C18) arylene, more preferably a single-bonded, unsubstituted (C6-C12) arylene, which can be, for example, a single-bonded or unsubstituted phenylene.

[0027] The compound represented by formula 3 can be represented by any one of the following formulas 3-1 to 3-6: [ka]

[0028] In equations 3-1 to 3-6 above, R 11 ~R 18 L2, X, and a'~d' are as defined in Equation 3.

[0029] In this specification, "(C1-C30) alkyl" is intended to be a linear or branched alkyl having 1 to 30 carbon atoms (preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms) constituting the chain, and includes methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl. "(C2-C30) alkenyl" is intended to be a linear or branched alkenyl having 2 to 30 carbon atoms (preferably 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms) constituting the chain, and includes vinyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 2-methylbuta-2-enyl, and the like. "(C2~C30)Alkynnyl" is intended to be a linear or branched alkynyl having 2 to 30 carbon atoms (preferably 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms) that constitute the chain, and includes ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-methylpento-2-inyl, etc. "(C3~C30)Cycloalkyl" is intended to be a monocyclic or polycyclic hydrocarbon having 3 to 30 ring skeleton carbon atoms (preferably 3 to 20 carbon atoms, more preferably 3 to 7 carbon atoms), and includes cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc. "(3 to 7-membered)Heterocycloalkyl" is intended to be a cycloalkyl having 3 to 7, preferably 5 to 7 ring skeleton atoms, including at least one heteroatom selected from the group consisting of B, N, O, S, Si, and P, preferably O, S, and N, and includes tetrahydrofuran, pyrrolidine, thiolane, tetrahydropyran, etc. "(C6~C60)aryl(ene)" is intended to be a monocyclic or fused ring group derived from an aromatic hydrocarbon having 6 to 60 ring skeleton carbon atoms (preferably 6 to 30, more preferably 6 to 20), and may be partially saturated or contain a spiro structure.Examples of the above-mentioned aryls include phenyl, biphenyl, terphenyl, naphthyl, binaphthyl, phenylnaphthyl, naphthylphenyl, fluorenyl, phenylfluorenyl, benzofluorenyl, dibenzofluorenyl, phenantrenyl, phenylphenantrenyl, anthracenyl, indenyl, triphenylethyleneyl, pyrenyl, tetracenyl, perilenyl, crisenyl, naphthacenyl, fluoranthenyl, and the like. The term "(3-30 member) heteroaryl (heteroarylene)" is intended to be an aryl having 3-30 ring skeleton atoms and containing at least one, preferably 1-4, heteroatoms selected from the group consisting of B, N, O, S, Si, and P. The above-mentioned heteroaryls may be monocyclic rings or fused rings fused with at least one benzene ring, may be partially saturated, and may be formed by bonding at least one heteroaryl or aryl group to a heteroaryl group via a single bond. Heteroaryls include monocyclic heteroaryls such as furyl, thiophenyl, pyrrolyl, imidazolyl, pyrazolyl, thiazolyl, thiadiazolyl, isothiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, triazinyl, tetradinyl, triazolyl, tetrazolyl, flazanyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, etc., and condensed cyclic heteroaryls such as benzofuranil, benzothiophenyl, isobenzofuranil, dibenzofuranil, dibenzothiophenyl, benzimidazolyl, benzothiazolyl, benzoisothiazolyl, benzoisoxazolyl, benzoxazolyl, isoindolyl, indolyl, benzoindolyl, indazolyl, benzothiadiazolyl, quinolyl, isoquinolyl, sinnolinyl, quinazolinyl, quinoxalinyl, naphthilidyl, carbazolyl, phenoxazinyl, phenantridinyl, benzodioxolyl, etc."Nitrogen-containing (5-30 member) heteroaryl" is intended to be an aryl group having at least one N and 5-30 ring skeleton atoms (preferably 5-20, more preferably 5-15 ring skeleton atoms), and preferably 1-4 heteroatoms, and may be a monocyclic ring or a fused ring fused with at least one benzene ring, may be partially saturated, and may be formed by bonding at least one heteroaryl or aryl group to a heteroaryl group by a single bond, and includes monocyclic heteroaryls such as pyrrolyl, imidazolyl, pyrazolyl, triazinyl, tetradinyl, triazolyl, tetrazolyl, pyridyl, pyrazinyl, pyrimidinyl, and pyridadinyl, and fused ring heteroaryls such as benzimidazolyl, isoindolyl, indolyl, indazolyl, benzothiadiazolyl, quinolyl, isoquinolyl, cinnolinyl, quinazolinyl, quinoxalinyl, carbazolyl, and phenantridinyl. "Halogens" include F, Cl, Br, and I.

[0030] Furthermore, in the expression "substituted or unsubstituted," "substituted" means that a hydrogen atom in a particular functional group is replaced by another atom or another functional group (i.e., a substituent). R1 ​​to R8 in formulas 1 to 3, R 11 ~R 18In L1 and L2, the substituents of substituted alkyl, substituted alkoxy, substituted cycloalkyl, substituted aryl(ene), substituted heteroaryl(ene), substituted trialkylsilyl, substituted triarylsilyl, substituted dialkylarylsilyl, substituted alkyldiarylsilyl, substituted mono- or di-alkylamino, substituted mono- or di-arylamino, substituted alkylarylamino, and substituted monocyclic or polycyclic, alicyclic or aromatic rings are each independently deuterium; halogen; cyano; carboxyl; nitro; hydroxyl; (C1~C30) aryl Kill; Halo(C1~C30)alkyl; (C2~C30)alkenyl; (C2~C30)alkynyl; (C1~C30)alkoxy; (C1~C30)alkylthio; (C3~C30)cycloalkyl; (3~7 member)heterocycloalkyl; (C6~C30)aryloxy; (C6~C30)arylthio; (C6~C30)aryl- or di(C6~C30)arylamino substituted or unsubstituted (3~30 member)heteroaryl; cyano-, (3~30 member)heteroaryl-, or tri(C6~C30)arylsilyl substituted or unsubstituted (C6~C30) Aryl; Tri(C1~C30)alkylsilyl; Tri(C6~C30)arylsilyl; Di(C1~C30)alkyl(C6~C30)arylsilyl; (C1~C30)alkyldi(C6~C30)arylsilyl; Amino; Mono- or di-(C1~C30)alkylamino; Mono- or di-(C6~C30)arylamino; (C1~C30)alkyl(C6~C30)arylamino; (C1~C30)alkylcarbonyl; (C1~C30)alkoxycarbonyl; (C6~C30)arylcarbonyl; Di(C6~C30)arylboro At least one selected from the group consisting of yl; di(C1~C30)alkylboronyl; (C1~C30)alkyl(C6~C30)arylboronyl; (C6~C30)al(C1~C30)alkyl; and (C1~C30)alkyl(C6~C30)aryl, preferably independently of each other, (C1~C20)alkyl; (C6~C18)aryl-substituted or unsubstituted (3~25 member) heteroaryl; cyano-, tri(C6~C18)arylsilyl-, or (3~20 member) heteroaryl-, substituted or unsubstituted (C6~C20)aryl;It is at least one selected from the group consisting of tri(C6-C18)arylsilyl and (C1-C20)alkyl(C6-C20)aryl compounds.

[0031] The compounds represented by formula 1 or 2 may, more specifically, be represented by, but are not limited to, the following compounds: [ka] [ka]

[0032] The compounds represented by formula 3 may, more specifically, be represented by, but are not limited to, the following compounds: [ka] [ka] [ka] [ka]

[0033] The organic electroluminescent device according to this disclosure comprises an anode, a cathode, and at least one organic layer between the anode and the cathode. The organic layer comprises a light-emitting layer containing a host and a phosphorescent dopant. The host comprises a plurality of host compounds, at least one of which is represented by formula 1 or 2 above, and the second host compound is represented by formula 3 above.

[0034] In this disclosure, the light-emitting layer is a layer that emits light and may be a single layer or a plurality of layers stacked together. In the light-emitting layer, the doping concentration of the dopant compound based on the host compound is preferably less than 20% by weight.

[0035] The organic layer may include an emissive layer and may further include at least one layer selected from a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, an intermediate layer, a hole blocking layer, and an electron blocking layer.

[0036] In the organic electroluminescent device of this disclosure, the weight ratio of the first host compound to the second host compound is in the range of 1:99 to 99:1.

[0037] The dopant included in the organic electroluminescent device according to this disclosure is preferably at least one phosphorescent dopant. The phosphorescent dopant material included in the organic electroluminescent device according to the present invention is not particularly limited, but can preferably be selected from metallized complex compounds of iridium (Ir), osmium (Os), copper (Cu), and platinum (Pt), more preferably from orthometallated complex compounds of iridium (Ir), osmium (Os), copper (Cu), and platinum (Pt), and even more preferably from orthometallated iridium complex compounds.

[0038] The dopants included in the organic electroluminescent devices of this disclosure may include, but are not limited to, compounds represented by the following formula 101: [ka] (In the formula, L is structure 1 or 2 below: [ka] Selected from, R 100 ~R 103 Each independently represents hydrogen, deuterium, halogen, halogen-substituted or unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C3-C30) cycloalkyl, substituted or unsubstituted (C6-C30) aryl, cyano, substituted or unsubstituted (3-30 member) heteroaryl, or substituted or unsubstituted (C1-C30) alkoxy; or R 100 ~R 103It may bond with adjacent substituents to form substituted or unsubstituted condensed rings, such as substituted or unsubstituted quinolines, substituted or unsubstituted benzophropyridines, substituted or unsubstituted benzothienopyridines, substituted or unsubstituted indenopyridines, substituted or unsubstituted benzophroquinolines, substituted or unsubstituted benzothienoquinolines, or substituted or unsubstituted indenoquinolines; R 104 ~R 107 Each independently represents hydrogen, deuterium, halogen, halogen-substituted or unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C3-C30) cycloalkyl, substituted or unsubstituted (C6-C30) aryl, substituted or unsubstituted (3-30 member) heteroaryl, cyano, or substituted or unsubstituted (C1-C30) alkoxy; or R 104 ~R 107 It may bond with adjacent substituents to form substituted or unsubstituted condensed rings, such as substituted or unsubstituted naphthyl, substituted or unsubstituted fluorene, substituted or unsubstituted dibenzothiophene, substituted or unsubstituted dibenzofuran, substituted or unsubstituted indenopyridine, substituted or unsubstituted benzoflopyridine, or substituted or unsubstituted benzothienopyridine; R 201 ~R 211 Each independently represents hydrogen, deuterium, halogen, halogen-substituted or unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C3-C30) cycloalkyl, or substituted or unsubstituted (C6-C30) aryl; or R 201 ~R 211 (The substituent may bond with an adjacent substituent to form a substituted or unsubstituted fused ring; n represents an integer from 1 to 3.)

[0039] Specific examples of dopant materials include the following: [ka] [ka] [ka] [ka]

[0040] The organic electroluminescent device of this disclosure may further contain at least one compound selected from the group consisting of arylamine compounds and styrylarylamine compounds in the organic layer.

[0041] Furthermore, in the organic electroluminescent device of this disclosure, the organic layer may further include at least one metal selected from the group consisting of Group 1 metals, Group 2 metals, Group 4 transition metals, Group 5 transition metals, lanthanides and organometallic compounds of d-transition elements of the periodic table, and at least one complex compound containing the aforementioned metals.

[0042] In the organic electroluminescent device of this disclosure, it may be preferable to arrange at least one layer selected from a chalcogenide layer, a metal halide layer, and a metal oxide layer (hereinafter referred to as a "surface layer") on the internal surface of one or both electrodes. Specifically, it is preferable to arrange a silicon or aluminum chalcogenide (including oxide) layer on the anode surface of the electroluminescent medium layer, and it is preferable to arrange a metal halide layer or a metal oxide layer on the cathode surface of the electroluminescent medium layer. Such surface layers can provide operational stability to the organic electroluminescent device. Preferably, the chalcogenide is SiO X (1≦X≦2), AlO X (1≦X≦1.5), including SiON, SiAlON, etc., the aforementioned metal halides include LiF, MgF2, CaF2, rare earth metal fluorides, etc., and the aforementioned metal oxides include Cs2O, Li2O, MgO, SrO, BaO, CaO, etc.

[0043] A hole injection layer, a hole transport layer, or an electron blocking layer, or a combination thereof, may be used between the anode and the light-emitting layer. The hole injection layer may be formed from multiple layers to lower the hole injection barrier (or hole injection voltage) from the anode to the hole transport layer or electron blocking layer. Two compounds can be used simultaneously in each layer. The hole transport layer or electron blocking layer may also be formed from multiple layers.

[0044] A layer selected from an electron buffer layer, a hole blocking layer, an electron transport layer, or an electron injection layer, or a combination thereof, may be used between the light-emitting layer and the cathode. The electron buffer layer may be formed from multiple layers to control electron injection and improve the interfacial properties between the light-emitting layer and the electron injection layer. Two compounds can be used simultaneously in each layer. In addition, the hole blocking layer or electron transport layer may be formed from multiple layers, and each layer may contain two or more compounds.

[0045] Furthermore, in the organic electroluminescent device of this disclosure, it is preferable that the mixed region of an electron transport compound and a reducing dopant or a mixed region of a hole transport compound and an oxidizing dopant is located on at least one surface of the electrode pair. In this case, the electron transport compound is reduced to anion, making it easier to inject and transport electrons from the mixed region to the electroluminescent medium. Furthermore, the hole transport compound is oxidized to a cation, making it easier to inject and transport holes from the mixed region to the electroluminescent medium. Preferably, the oxidizing dopant includes various Lewis acids and acceptor compounds, and the reducing dopant includes alkali metals, alkali metal compounds, alkaline earth metals, rare earth metals, and mixtures thereof. An organic electroluminescent device having two or more light-emitting layers and emitting white light can be prepared by using the reducing dopant layer as a charge-generating layer.

[0046] To form each layer of the organic electroluminescent device of this disclosure, dry deposition methods such as vacuum deposition, sputtering, plasma and ion plating, or wet deposition methods such as inkjet printing, nozzle printing, slot coating, spin coating, dip coating and flow coating can be used.

[0047] When using a wet film formation method, thin films can be formed by dissolving or diffusing the materials forming each layer into any suitable solvent such as ethanol, chloroform, tetrahydrofuran, or dioxane. Any solvent can be used as long as the materials forming each layer can be dissolved or diffused and there are no problems with film formation.

[0048] Furthermore, the first and second host compounds of this disclosure may be evaporated simultaneously or mixed.

[0049] By using the organic electroluminescent device of this disclosure, a display system or a lighting system can be manufactured.

[0050] The organic electroluminescent compounds, methods for preparing them, and the luminescence properties of organic electroluminescent devices containing them are described in detail below with respect to representative compounds of this disclosure in order to fully understand this disclosure.

[0051] Example 1: Preparation of compound H1-1 [ka] Compound 1-1 (4 g, 12 mmol), bis(biphenyl-4-yl)[4-(4,4,5,5-tetramethyl-[1,3,2]-dioxaboran-2-yl)phenyl]amine (6.8 g, 13 mmol), palladium(II) acetate (0.3 g, 1 mmol), 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (0.9 g, 2 mmol), cesium carbonate (11.5 g, 35 mmol), 60 mL of o-xylene, 15 mL of ethanol, and 15 mL of distilled water were added to the reactor and refluxed for 3 hours. After the reaction was complete, the organic layer was washed with distilled water and extracted with ethyl acetate. Next, the organic layer was dried over magnesium sulfate. The solvent was removed using a rotary evaporator, and the resulting product was purified by column chromatography to obtain compound H1-1 (2.2 g, yield: 27%).

[0052] [Table 1]

[0053] Example 2: Preparation of compound H1-42 [ka] Compound 2-1 (4.8 g, 11.34 mmol), N-(4-bromophenyl)-N-phenyl-[1,1'-biphenyl]-4-amine (5 g, 12.47 mmol), tetrakis(triphenylphosphine)palladium (0.4 g, 0.34 mmol), sodium carbonate (3.0 g, 28.35 mmol), 57 mL of toluene, 14 mL of ethanol, and 14 mL of distilled water were added to the reactor and stirred at 120°C for 4 hours. After the reaction was complete, methanol was added dropwise to the mixture, and the resulting solid was filtered. The resulting solid was purified by column chromatography and recrystallized to obtain compound H1-42 (1.4 g, yield: 20.0%).

[0054] [Table 2]

[0055] Example 3: Preparation of compound H1-27 [ka] Compound 3-1 (4.5 g, 16.09 mmol), 9,9-dimethyl-N-phenyl-9H-fluoren-2-amine (5.5 g, 19.31 mmol), palladium(II) acetate (0.2 g, 0.80 mmol), tri-t-butylphosphine (0.8 mL, 1.60 mmol), sodium tert-butoxide (2.3 g, 24.14 mmol), and 80 mL of o-xylene were added to the reactor and refluxed at 120°C for 2 hours. After the reaction was complete, the mixture was cooled to room temperature, the resulting solid was filtered, and washed with ethyl acetate. The filtrate was distilled under reduced pressure, and the resulting solid was purified by column chromatography and recrystallized to obtain compound H1-27 (2.4 g, yield: 28%).

[0056] [Table 3]

[0057] Example 4: Preparation of compound H2-1 [ka] Compound 2-1 (10 g, 23.7 mmol), 2-chloro-4,6-diphenyltriazine (CAS: 3842-55-5, 5.8 g, 21.6 mmol), tetrakis(triphenylphosphine)palladium (1.2 g, 1.0 mmol), potassium carbonate (7.5 g, 59 mmol), 90 mL of toluene, 30 mL of ethanol, and 30 mL of distilled water were added to the reactor and stirred at 120 °C for 4 hours. After the reaction was complete, methanol was added dropwise to the mixture, and the resulting solid was filtered. The resulting solid was purified by column chromatography and recrystallized to obtain compound H2-1 (5.7 g, yield: 50%).

[0058] [Table 4]

[0059] Example 5: Preparation of compound H2-2 [ka] Compound 2-1 (3.48 g, 8.3 mmol), 2-([1,1'-biphenyl]-4-yl)-4-chloro-6-phenyl-1,3,5-triazine (CAS: 1472062-94-4, 3.53 g, 9.1 mmol), tetrakis(triphenylphosphine)palladium (0.48 g, 0.41 mmol), sodium carbonate (2.2 g, 20.7 mmol), 28 mL of toluene, 7 mL of ethanol, and 7 mL of distilled water were added to the reactor and stirred at 120 °C for 5 hours. After the reaction was complete, methanol was added dropwise to the mixture, and the resulting solid was filtered. The resulting solid was purified by column chromatography and recrystallized to obtain compound H2-2 (3.7 g, yield: 74%).

[0060] [Table 5]

[0061] The LUMO (lowest empty molecular orbital) energy, HOMO (highest occupied molecular orbital) energy, and triplet energy of compounds H1-1 and H1-27 synthesized in Examples 1 and 3 above were calculated using density functional theory (DFT) at the B3LYP / 6-31g(d) level and are shown in Table 1 below.

[0062] Basically, the LUMO and HOMO energy values ​​measured as described above have negative values; however, for convenience, they are expressed as absolute values. Furthermore, when comparing the degrees of LUMO / HOMO energy values, it is their absolute values ​​that are compared.

[0063] [Table 6]

[0064] Referring to Table 1 above, the device characteristics of the first host compounds according to one embodiment, namely compound H1-1 represented by formula 1 and compound H1-27 represented by formula 2, can be compared and predicted. Specifically, compound H1-27 has a HOMO energy value similar to compound H1-1 and a lower LUMO energy value than compound H1-1. Therefore, it is expected that electron carriers will be sufficiently confined when compound H1-27 is used. Furthermore, when host compounds H1-1 and H1-27 are combined with a host having strong electron current characteristics, it can be confirmed that their energy values ​​do not pose a problem for exciplex formation. In addition, the triplet energy values ​​of compounds H1-1 and H1-27 are 2.4 eV and 2.5 eV, respectively, which are sufficient to block the triplet energy of the dopant. That is, when compound H1-1 or H1-27 is used as the first host compound according to one embodiment, it can be expected that a device containing one of them will exhibit similar device characteristics to a device containing the other.

[0065] Therefore, in the following device examples, an organic electroluminescent device is manufactured by using only compounds H1-1 and H1-42 represented by Formula 1 as representative first host compounds, and the characteristics of the device are described.

[0066] Comparative Example 1: Fabrication of a red-emitting organic electroluminescent device not according to this disclosure An OLED device not described herein was fabricated. First, a transparent electrode indium tin oxide (ITO) thin film (10 Ω / sq) of an OLED glass substrate (Geomatec Co., Ltd., Japan) was sequentially ultrasonically cleaned with acetone and isopropyl alcohol, and then stored in isopropanol. Next, the ITO substrate was mounted in the substrate holder of a vacuum deposition apparatus. Compound HI-1 was introduced into the cell of the vacuum deposition apparatus, and then the pressure in the chamber of the apparatus was set to 10 -7The vacuum was controlled to Thor. Then, an electric current was passed through the cell to evaporate the introduced material, thereby forming a first hole injection layer with a thickness of 80 nm on the ITO substrate. Next, compound HI-2 was introduced into another cell of the vacuum deposition apparatus, and an electric current was applied to the cell to evaporate the introduced material, thereby forming a second hole injection layer with a thickness of 5 nm on the first hole injection layer. Next, compound HT-1 was introduced into another cell of the vacuum deposition apparatus. Then, an electric current was passed through the cell to evaporate the introduced material, thereby forming a first hole transport layer with a thickness of 10 nm on the second hole injection layer. Subsequently, compound HT-2 was introduced into another cell of the vacuum deposition apparatus, and an electric current was passed through the cell to evaporate the introduced material, thereby forming a second hole transport layer with a thickness of 60 nm on the first hole transport layer. After forming the hole injection layer and the hole transport layer, the light-emitting layer was deposited as follows. Compound H1-1 was introduced as the host in one cell of a vacuum deposition apparatus, and compound D-39 was introduced as the dopant in another cell of the apparatus. The two materials were evaporated at different rates, and the dopant was deposited at a doping amount of 3 wt% based on the total amount of host and dopant to form a 40 nm thick light-emitting layer on the second hole transport layer. Next, compounds ETL-1 and EIL-1 were deposited on the light-emitting layer as electron transport materials in a 50:50 weight ratio to form a 35 nm thick electron transport layer. Then, compound EIL-1 was deposited on the electron transport layer to a thickness of 2 nm as an electron injection layer, and then an 80 nm thick Al cathode was deposited on the electron injection layer using another vacuum deposition apparatus. In this way, an OLED device was fabricated. All materials used to fabricate the OLED device were 10 -6 It was purified by vacuum sublimation using a Thor's oak microscope.

[0067] Comparative Example 2: Fabrication of a red-emitting organic electroluminescent device not according to the present disclosure An OLED device was manufactured using the same method as in Comparative Example 1, except that compound H2-2 was used instead of H1-1 as the light-emitting material.

[0068] Comparative Example 3: Fabrication of a red-emitting organic electroluminescent device not according to the present disclosure An OLED device was manufactured using the same method as in Comparative Example 1, except that compound H2-1 was used instead of H1-1 as the light-emitting material.

[0069] Device Examples 1-3: Fabrication of Red Emitting Organic Electroluminescent Devices According to the Disclosure In Device Examples 1 to 3, OLED devices were manufactured in the same manner as in Comparative Example 1, except that the first and second host compounds listed in Table 2 were introduced as hosts into one cell of a vacuum deposition apparatus, and compound D-39 was introduced as a dopant into another cell of the apparatus. The two host materials were evaporated simultaneously in the same 1:1 ratio, and the dopant was evaporated at different rates with a doping amount of 3% by weight based on the total weight of the host and dopant, to form a 40 nm thick light-emitting layer.

[0070] Table 2 below shows the driving voltage, luminous efficiency, and CIE color coordinates at a brightness of 1,000 nits for the organic electroluminescent devices of Comparative Examples 1-3 and Device Examples 1-3 manufactured as described above, and the time taken for the luminescence to decrease from 100% to 90% at a brightness of 5,000 nits (lifetime; T90). Furthermore, Figure 1 shows the current efficiency with respect to brightness for the organic electroluminescent devices manufactured in Comparative Example 2 and Device Example 1.

[0071] [Table 7]

[0072] From the above device examples 1 to 3, it was confirmed that the compound combinations of the present disclosure can significantly improve efficiency and lifetime characteristics while maintaining a driving voltage similar to that of the comparative examples. Specifically, referring to Figure 1, the combination of light-emitting layers as an organic electroluminescent device according to one embodiment shows a significant improvement in roll-off compared to the comparative example, which is a combination of a single light-emitting layer.

[0073] The compounds used in the comparative examples and device examples are shown in Table 3 below.

[0074] Table 8

Claims

1. A plurality of host materials comprising at least one first host compound and at least one second host compound, The first host compound is represented by the following formulas 1-4: 【Chemistry 1】 (In the formula, R １ This represents a substituted or unsubstituted (C6-C30) aryl, or a substituted or unsubstituted (3-30 member) heteroaryl. R ２ , R ５ And R 6 can independently represent hydrogen, deuterium, halogen, cyano, substituted or unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C6-C30) aryl, substituted or unsubstituted (3-30 member) heteroaryl, substituted or unsubstituted mono- or di-(C1-C30) alkylamino, substituted or unsubstituted mono- or di-(C6-C30) arylamino, or substituted or unsubstituted (C1-C30) alkyl(C6-C30) arylamino, or bond with adjacent substituents to form substituted or unsubstituted (C3-C30) monocyclic or polycyclic, alicyclic, or aromatic rings, where these carbon atoms may be substituted with at least one heteroatom selected from nitrogen, oxygen, and sulfur. R3 represents hydrogen, deuterium, halogen, cyano, substituted or unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C6-C30) aryl, substituted or unsubstituted (3-30 member) heteroaryl, substituted or unsubstituted mono- or di-(C1-C30) alkylamino, substituted or unsubstituted mono- or di-(C6-C30) arylamino, or substituted or unsubstituted (C1-C30) alkyl(C6-C30) arylamino. L １ This represents a single bond, a substituted or unsubstituted (C6-C30) arylene, or a substituted or unsubstituted (3-30 member) heteroarylene. a represents 1, b represents 1 or 2, e represents an integer from 1 to 4, The heteroaryl(ene) comprises at least one heteroatom selected from B, N, O, S, Si, and P. Represented by, The second host compound is given by the following formula 3-1: 【Chemistry 2】 (In the formula, X represents N or CH, R １１ This represents a substituted or unsubstituted (C6-C30) aryl, or a substituted or unsubstituted (3-30 member) heteroaryl. R １２ Each of the R16 atoms can independently represent hydrogen, deuterium, halogen, cyano, substituted or unsubstituted (C1-C30) alkyl, substituted or unsubstituted (C6-C30) aryl, or substituted or unsubstituted (3-30 member) heteroaryl, or can bond with adjacent substituents to form substituted or unsubstituted (C3-C30) monocyclic or polycyclic, alicyclic, or aromatic rings, where these carbon atoms may be substituted with at least one heteroatom selected from nitrogen, oxygen, and sulfur. L ２ This represents a single bond, a substituted or unsubstituted (C6-C30) arylene, or a substituted or unsubstituted (3-30 member) heteroarylene. a' represents 1, b' and c' each independently represent 1 or 2. d' represents an integer from 1 to 4, The heteroaryl(ene) comprises at least one heteroatom selected from B, N, O, S, Si, and P. Multiple host materials represented by [this].

2. R １ to R ３ , R ５ , R6, R １１ to R16, L １ and L ２ wherein the substituted alkyl, the substituted aryl(ene), the substituted heteroaryl(ene), the substituted mono- or di-alkylamino, the substituted mono- or di-arylamino, the substituted alkylarylamino, and the substituents of the substituted monocyclic or polycyclic, alicyclic, or aromatic ring in R, R, R, R6, R, R16, L, and L are each independently deuterium; halogen; cyano; carboxyl; nitro; hydroxyl; (C1-C30)alkyl; halo(C1-C30)alkyl; (C2-C30)alkenyl; (C2-C30)alkynyl; (C1-C30)alkoxy; (C1-C30)alkylthio; (C3-C30)cycloalkyl; (3-7 member)heterocycloalkyl; (C6-C30)aryloxy; (C6-C30)arylthio; (C6-C30)aryl- or di(C6-C30)arylamino-substituted or unsubstituted (3-30 member)heteroaryl; cyano-, (3-30 member)heteroaryl- or tri(C6-C30)arylsilyl-substituted or unsubstituted (C6-C30)aryl; tri(C1-C30)alkylsilyl; tri(C6-C30)arylsilyl; di(C1-C30)alkyl(C6-C30)arylsilyl; (C1-C30)alkyldi(C6-C30)arylsilyl; amino; mono- or di-(C1-C30)alkylamino; mono- or di-(C6-C30)arylamino; (C1-C30)alkyl(C6-C30)arylamino; (C1-C30)alkylcarbonyl; (C1-C30)alkoxycarbonyl; (C6-C30)arylcarbonyl; di(C6-C30)arylboronyl; di(C1-C30)alkylboronyl; (C1-C30)alkyl(C6-C30)arylboronyl; (C6-C30)al(C1-C30)alkyl; and (C1-C30)alkyl(C6-C30)aryl, and is at least one selected from the group consisting of, the host material according to claim 1.

3. The first host compound is 【Transformation 3】 A host material according to claim 1, selected from the group consisting of the following.

4. The second host compound is 【Chemistry 4】 A host material according to claim 1, selected from the group consisting of the following.

5. An organic electroluminescent device comprising an anode, a cathode, and at least one light-emitting layer between the anode and the cathode, wherein the light-emitting layer comprises a host and a phosphorescent dopant, and the host comprises the host material described in claim 1.

Images