An organic electroluminescent device

Abstract

The present invention relates to an organic electroluminescent device, the organic electroluminescent device comprises a first electrode, a second electrode and an organic layer located between the first electrode and the second electrode, the organic layer comprises a light-emitting layer and an electron transport layer, the material of the electron transport layer is a mixture of ETL1 and ETL2; the ETL1 material comprises any one of the compounds shown in formula (1), and the ETL2 material comprises any one of the compounds shown in formula (2). The present invention can exert a performance superior to that of the electron transport material of formula (1) and the electron transport material of formula (2) by mixing them for use, and the synergistic effect of the two can further balance the carriers and enhance the stability of the electron transport layer, thereby improving the luminous efficiency of the device, reducing the driving voltage, and prolonging the service life.

Description

Technical Field

[0001] The invention relates to the technical field of organic electroluminescence, and in particular to an organic electroluminescence device. Background Art

[0002] The core of OLED devices is a thin film structure containing a variety of organic functional materials. Common functionalized organic materials include: hole injection materials, hole transport materials, hole blocking materials, electron injection materials, electron transport materials, electron blocking materials, luminescent host materials and luminescent guest (dyes), etc. When power is turned on, electrons and holes are injected and transported to the luminescent area respectively and recombine there, thereby generating excitons and emitting light.

[0003] In order to further meet the ever-increasing demand for the optoelectronic performance of OLED devices and the energy-saving needs of mobile electronic devices, it is necessary to continuously develop new and efficient OLED materials, among which it is of great significance to improve the stability of the electron transport layer and balance the carriers to improve the overall performance of the device.

[0004] In recent years, people in the industry have been constantly trying and exploring to improve device efficiency and stability. Most of them are seeking new materials to improve device performance. A large number of novel materials have been developed for use in organic electroluminescent devices. Although they have improved device performance to a certain extent, they still have problems such as insufficient material stability and carrier imbalance, resulting in high device voltage and short life.

[0005] Therefore, there is an urgent need to develop organic electroluminescent devices with higher performance in this field. Summary of the invention

[0006] In view of the shortcomings of the prior art, one of the purposes of the present invention is to provide an organic electroluminescent device having a lower driving voltage, and higher luminous efficiency and lifespan.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] The present invention provides an organic electroluminescent device, comprising a first electrode, a second electrode and an organic layer located between the first electrode and the second electrode, wherein the organic layer comprises a light-emitting layer and an electron transport layer, wherein the electron transport layer comprises a mixture of a first electron transport material ETL1 and a second electron transport material ETL2, wherein the molar mass ratio of ETL1 to ETL2 is 1:9-9:1, and preferably the molar mass ratio of ETL1 to ETL2 is 3:7-7:3.

[0009] A compound comprising the structure shown in formula (1):

[0010]

[0011] In formula (1), Ar1 is selected from a substituted or unsubstituted C12-C60 aryl group, a substituted or unsubstituted C3-C60 heteroaryl group;

[0012] R a ~R b Each is independently selected from one of hydrogen, C1-C12 aliphatic hydrocarbon group, C1-C12 aliphatic hydrocarbonoxy group, halogen, cyano group, nitro group, hydroxyl group, C1-C30 silane group, amino group, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C3-C30 heteroaryl group;

[0013] R 1 ~R 4 Each is independently selected from hydrogen, C1-C12 aliphatic hydrocarbon group, C1-C12 aliphatic hydrocarbonoxy group, halogen, cyano, nitro, hydroxyl, C1-C30 silane group, amino, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C3-C30 heteroaryl group, R 1 and R 2 Can be interconnected to form a ring, R 3 and R 2 Can be interconnected to form a ring, R 3 and R 4 Can be interconnected to form a ring;

[0014] The above Ar1, R a ~R b , R 1 ~R 4 When there is a substituent, it means that it is substituted by one or more substituents selected from halogen, C1-C12 aliphatic hydrocarbon group, C1-C12 aliphatic hydrocarbonoxy group, C6-C12 aryl group, C3-C12 heteroaryl group, cyano group, and hydroxyl group.

[0015] The ETL2 comprises a compound having a structure as shown in formula (2):

[0016]

[0017] In formula (2), L is selected from a substituted or unsubstituted C6-C30 arylene group; preferably, when L is selected from a substituted arylene group, the substituent is a C3-C30 heteroaryl group;

[0018] R 5 , R 6 and R 7 Each is independently selected from one of hydrogen, cyano, substituted or unsubstituted C1-C10 alkyl or cycloalkyl, substituted or unsubstituted C6-C30 aryl, and substituted or unsubstituted C3-C30 heteroaryl;

[0019] Ar2 is a substituent group represented by the following formula (A):

[0020]

[0021] In formula (A), X 1 ~X 6 Each is independently selected from a nitrogen atom, CH or CR, and at least one of them is a nitrogen atom, and each R is independently selected from one of a C1-C10 alkyl group, a C1-C10 alkoxy group, a substituted or unsubstituted C6-C30 aryl group, and a substituted or unsubstituted C3-C30 heteroaryl group;

[0022] When the above L, R, X 1 ~X 6 , R 5 , R 6 and R 7 When substituents are present, the substituents are independently selected from one of halogen, C1-C10 alkyl or cycloalkyl, C2-C10 alkenyl, C1-C6 alkoxy or thioalkoxy groups, C6-C30 aryl, and C3-C30 heteroaryl.

[0023] Preferably, in formula (1): Ar1 is selected from substituted or unsubstituted C12-C30 aryl, substituted or unsubstituted C8-C30 heteroaryl, and Ar1 is a fused aryl or fused heteroaryl with a large conjugated structure, and the fused aryl or fused heteroaryl with a large conjugated structure is a conjugated system with 14 to 24 conjugated π electrons; preferably Ar1 is a conjugated system with 14 to 18 conjugated π electrons; R a ~R b Each is independently selected from one of halogen, cyano, nitro, hydroxyl, substituted or unsubstituted C6-C30 aryl, and substituted or unsubstituted C3-C30 heteroaryl.

[0024] More preferably, in formula (1):

[0025] Ar1 is selected from the group consisting of phenanthryl, triphenylene, fluoranthenyl, anthracene, pyrene, dihydropyrene, anise, perylene, fluoranthene, benzanthracene, triphenylene, tetracene, pentacene, benzopyrene, benzofuran, isobenzofuran, benzothiophene, isobenzothiophene, quinoline, isoquinoline, acridine, phenanthridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, phenothiazine, phenazine, indazole, benzimidazole, naphthalene One or a combination of two of imidazole, phenanthroimidazole, pyrazole, benzopyrazole, pyridopyridine, pyridoimidazole, pyrazinoimidazole, quinoxalinoimidazole, benzoxazole, naphthoxazole, anthraxazole, phenanthroxiazole, benzothiazole, benzopyridazine, pyrimidine, benzopyrimidine, quinoxaline, phenazine, naphthyridine, azacarbazole, benzocarboline, phenanthroline, benzotriazole, purine, pteridine, indolizine, and benzothiadiazole;

[0026] R a ~R b One or a combination of two selected from phenyl, naphthyl, biphenyl, fluorenyl, pyridyl, furanyl, thienyl, diphenylpropanefuranyl, and dibenzothienyl;

[0027] R 1 ~R 4 Each is independently selected from hydrogen, methyl, ethyl, isopropyl, tert-butyl, phenyl, biphenyl, terphenyl, naphthyl, anthracenyl, phenanthrenyl, indenyl, fluorenyl, fluoranthenyl, triphenylene, pyrenyl, peryl, The invention also includes one or two of the following: phenyl, tetraphenyl, furanyl, thienyl, pyrrolyl, benzofuranyl, benzothienyl, isobenzofuranyl, indolyl, dibenzofuranyl, dibenzothienyl, carbazolyl, benzodioxolyl, pyridyl, phenylpyridyl, quinolyl, quinazolinyl, quinoxalinyl, pyrimidinyl, o-phenanthroline, triazine, benzimidazolyl, and oxazolyl.

[0028] More preferably, Ar1 is selected from one of the following groups:

[0029]

[0030] "*" represents the connection site with the parent nucleus, and the connection bond of the substituent "—" is represented by crossing the ring structure, indicating that the connection site is at any bonding position on the ring structure. The hydrogen atoms on these groups can be replaced, and the substituents are selected from halogen, C1-C12 aliphatic hydrocarbon groups, C1-C12 aliphatic hydrocarbon groups, C6-C12 aryl groups, C3-C12 heteroaryl groups, cyano groups, and hydroxyl groups.

[0031] Preferably, the ETL1 comprises any one of the following compounds:

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038] Preferably, the ETL2 comprises a compound having a structure as shown in formula (2-1), (2-2), (2-3) or (2-4):

[0039]

[0040] Among them, R 5 , R 6 , R 7 and L are defined as in the general formula (1);

[0041] R 8 One selected from hydrogen, cyano, substituted or unsubstituted C1-C10 alkyl, C1-C10 alkoxy, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C30 heteroaryl; m is zero to the maximum allowed integer value.

[0042] More preferably, the ETL2 comprises any one of the following compounds:

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051] It should be noted that in this specification, the expression of Ca to Cb means that the number of carbon atoms in the group is a to b. Unless otherwise specified, the number of carbon atoms does not include the number of carbon atoms in the substituent. In the present invention, the expression of chemical elements, unless otherwise specified, usually includes the concept of isotopes with the same chemical properties. For example, the expression of "hydrogen" also includes the concept of "deuterium" and "tritium" with the same chemical properties. Carbon (C) includes 12 C. 13 C, etc., no further details.

[0052] In the structural formula disclosed in this specification, the expression of the ring structure crossed by “—” indicates that the connection site is any position on the ring structure that can form a bond.

[0053] In this specification, unless otherwise specified, aryl and heteroaryl include both monocyclic and condensed rings. The so-called monocyclic aryl refers to a molecule containing at least one phenyl group. When the molecule contains at least two phenyl groups, the phenyl groups are independent of each other and connected by a single bond, such as phenyl, biphenyl, terphenyl, etc.; condensed ring aryl refers to a molecule containing at least two benzene rings, but the benzene rings are not independent of each other, but condensed to each other by sharing the ring edge, such as naphthyl, anthracenyl, etc.; monocyclic heteroaryl refers to a molecule containing at least one heteroaryl group. When the molecule contains one heteroaryl group and other groups (such as aryl, heteroaryl, alkyl, etc.), the heteroaryl group and other groups are independent of each other and connected by a single bond, such as pyridine, furan, thiophene, etc.; condensed ring heteroaryl refers to a molecule composed of at least one phenyl group and at least one heteroaryl group fused together, or at least two heteroaryl rings fused together, such as quinoline, isoquinoline, benzofuran, dibenzofuran, benzothiophene, dibenzothiophene, etc.

[0054] In the present specification, the substituted or unsubstituted C6-C30 aryl group is preferably a C6-C20 aryl group, and more preferably a group selected from the group consisting of phenyl, naphthyl, anthracenyl, benzanthryl, phenanthryl, triphenylenyl, pyrene, chrysene, peryl, fluoranthene, naphthyl, pentacene, benzopyrene, biphenyl, isophenyl, terphenyl, triphenyl, tetraphenyl, fluorenyl, spirobifluorenyl, dihydrophenanthryl, dihydropyrenyl, tetrahydropyrenyl, cis- or trans-indenofluorenyl, trimerized indenyl, isotrimerized indenyl, spirotrimerized indenyl, and spiroisotrimerized indenyl. Specifically, the biphenyl group is selected from 2-biphenyl, 3-biphenyl and 4-biphenyl; the terphenyl group includes p-terphenyl-4-yl, p-terphenyl-3-yl, p-terphenyl-2-yl, m-terphenyl-4-yl, m-terphenyl-3-yl and m-terphenyl-2-yl; the naphthyl group includes 1-naphthyl or 2-naphthyl; the anthracenyl group is selected from 1-anthracenyl, 2-anthracenyl and 9-anthracenyl; the fluorenyl group is selected from 1-fluorenyl, 2-fluorenyl, 3-fluorenyl, 4-fluorenyl and 9-fluorenyl; the pyrenyl group is selected from 1-pyrenyl, 2-pyrenyl and 4-pyrenyl; the tetraphenyl group is selected from 1-tetraphenyl, 2-tetraphenyl and 9-tetraphenyl. Preferred examples of the aryl group in the present invention include phenyl, biphenyl, terphenyl, naphthyl, anthracenyl, phenanthrenyl, indenyl, fluorenyl and its derivatives, fluoranthenyl, triphenylene, pyrenyl, peryl, The biphenyl group is selected from the group consisting of 2-biphenyl, 3-biphenyl and 4-biphenyl; the terphenyl group includes p-terphenyl-4-yl, p-terphenyl-3-yl, p-terphenyl-2-yl, m-terphenyl-4-yl, m-terphenyl-3-yl and m-terphenyl-2-yl; the naphthyl group includes 1-naphthyl or 2-naphthyl; the anthracenyl group is selected from the group consisting of 1-anthracenyl, 2-anthracenyl and 9-anthracenyl. The fluorenyl group is selected from the group consisting of 1-fluorenyl, 2-fluorenyl, 3-fluorenyl, 4-fluorenyl and 9-fluorenyl; the fluorenyl derivative is selected from the group consisting of 9,9-dimethylfluorene, 9,9-spirobifluorene and benzofluorene; the pyrenyl group is selected from the group consisting of 1-pyrenyl, 2-pyrenyl and 4-pyrenyl; the naphthyl group is selected from the group consisting of 1-naphthyl, 2-naphthyl and 9-naphthyl. The C6-C30 aryl group of the present invention can also be a group formed by combining the above groups by single bond connection or / and fusion.

[0055] The heteroatom in the present invention is generally selected from N, O, S, P, Si and Se, preferably selected from N, O and S.

[0056] In the present specification, the substituted or unsubstituted C3-C60 heteroaryl group is preferably a C3-C30 heteroaryl group, more preferably a nitrogen-containing heteroaryl group, an oxygen-containing heteroaryl group, a sulfur-containing heteroaryl group, etc. Specific examples include: furyl, thienyl, pyrrolyl, pyridyl, benzofuranyl, benzothienyl, isobenzofuranyl, isobenzothienyl, indolyl, isoindolyl, dibenzofuranyl, dibenzothienyl, carbazolyl and its derivatives, quinolyl, isoquinolyl, acridinyl, phenanthridine yl, benzo-5,6-quinolyl, benzo-6,7-quinolyl, benzo-7,8-quinolyl, phenothiazinyl, phenazinyl, pyrazolyl, indazolyl, imidazolyl, benzimidazolyl, naphthoimidazolyl, phenanthroimidazolyl, pyridoimidazolyl, pyrazinoimidazolyl, quinoxalinoimidazolyl, oxazolyl, benzoxazolyl, naphthoxazolyl, anthrazolyl, phenanthroxazolyl, 1,2-thiazolyl, 1,3-thiazolyl, benzothiazolyl, pyridazinyl, benzopyridazinyl, pyrimidazinyl, pyridinyl, benzopyrimidinyl, quinoxalinyl, 1,5-diazaanthryl, 2,7-diazapyrenyl, 2,3-diazapyrenyl, 1,6-diazapyrenyl, 1,8-diazapyrenyl, 4,5-diazapyrenyl, 4,5,9,10-tetraazaperyl, pyrazinyl, phenazinyl, phenothiazinyl, naphthyridinyl, azacarbazolyl, benzocarbolinyl, phenanthrolinyl, 1,2,3-triazolyl, 1,2,4-triazolyl, benzotriazolyl, 1,2,3-oxadiazolyl, oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl, 1,3,4-thiadiazolyl, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, tetrazolyl, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine, purinyl, pteridinyl, indolizine, benzothiadiazole and the like. Preferred examples of heteroaryl groups in the present invention include furanyl, thienyl, pyrrolyl, benzofuranyl, benzothienyl, isobenzofuranyl, indolyl, dibenzofuranyl, dibenzothienyl, carbazolyl and derivatives thereof, wherein the carbazolyl derivative is preferably 9-phenylcarbazole, 9-naphthylcarbazolebenzocarbazole, dibenzocarbazole or indolecarbazole. The C3-C60 heteroaryl group of the present invention may also be a group formed by combining the above groups by single bond connection or / and fusion.

[0057] In the present specification, examples of the C1-C10 alkyl or cycloalkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 2-methylbutyl, n-pentyl, sec-pentyl, cyclopentyl, neopentyl, n-hexyl, cyclohexyl, adamantyl, neohexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, 2-ethylhexyl and the like.

[0058] In the present specification, examples of C1-C10 alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, isobutoxy, tert-butoxy, pentyloxy, isopentyloxy, hexyloxy, heptyloxy, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, etc., among which methoxy, ethoxy, n-propoxy, isopropoxy, tert-butoxy, sec-butoxy, isobutoxy, isopentyloxy, and methoxy is more preferred.

[0059] In the present specification, examples of C1-C30 silyl groups include silyl groups substituted with the groups listed in the above C1-C30 alkyl groups, specifically including methylsilyl, dimethylsilyl, trimethylsilyl, ethylsilyl, diethylsilyl, triethylsilyl, tert-butyldimethylsilyl, tert-butyldiphenylsilyl and the like.

[0060] In the present specification, examples of halogen include fluorine, chlorine, bromine, and iodine.

[0061] More specifically, as the above-mentioned R 1 ~R 8The group of the present invention preferably includes hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 2-methylbutyl, n-pentyl, sec-pentyl, cyclopentyl, neopentyl, n-hexyl, cyclohexyl, neohexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, 2-ethylhexyl, trifluoromethyl, pentafluoroethyl, 2,2,2-trifluoroethyl, phenyl, naphthyl, anthracenyl, benzanthryl, phenanthryl, triphenylene, pyrenyl, chrysene, peryl, fluoranthenyl, naphthyl, pentacene, benzopyrenyl, biphenyl, phenylene, terphenylene, triphenylene, quaternaryl, fluorenyl, spirobifluorenyl, di ... phenanthrenyl, dihydropyrenyl, tetrahydropyrenyl, cis- or trans-indenofluorenyl, trimerized indenyl, isotrimerized indenyl, spirotrimerized indenyl, spiroisotrimerized indenyl, furanyl, benzofuranyl, isobenzofuranyl, dibenzofuranyl, thienyl, benzothienyl, isobenzothienyl, dibenzothienyl, pyrrolyl, isoindolyl, carbazolyl, indenocarbazolyl, pyridinyl, quinolyl, isoquinolyl, acridinyl, phenanthridinyl, benzo-5,6-quinolyl, benzo-6,7-quinolyl, benzo-7,8-quinolyl, pyrazolyl, indazolyl, imidazolyl, benzimidazolyl, naphthoimidazolyl, phenanthroimidazolyl, pyridoimidazolyl , pyrazinoimidazolyl, quinoxalinoimidazolyl, oxazolyl, benzoxazolyl, naphthoxazolyl, anthrazolyl, phenanthroxazolyl, 1,2-thiazolyl, 1,3-thiazolyl, benzothiazolyl, pyridazinyl, benzopyridazinyl, pyrimidinyl, benzopyrimidinyl, quinoxalinyl, 1,5-diazaanthryl, 2,7-diazapyrenyl, 2,3-diazapyrenyl, 1,6-diazapyrenyl, 1,8-diazapyrenyl, 4,5-diazapyrenyl, 4,5,9,10-tetraazaperyl, pyrazinyl, phenazinyl, phenothiazinyl, naphthyridinyl, azacarbazolyl, benzocarbolinyl, phenanthrolinyl, 1,2, 3-triazolyl, 1,2,4-triazolyl, benzotriazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl, 1,2,5-oxadiazolyl, 1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl, 1,3,4-thiadiazolyl, 1,3,5-triazinyl, 1,2,4-triazinyl, 1,2,3-triazinyl, tetrazolyl, 1,2,4,5-tetrazinyl, 1,2,3,4-tetrazinyl, 1,2,3,5-tetrazinyl, purinyl, pteridinyl, indolizinyl, benzothiadiazolyl, or a combination of two of the above groups.

[0062] In the present invention, the "substituted or unsubstituted" group may be substituted with one substituent or with multiple substituents. When there are multiple substituents, they may be selected from different substituents. When the same expressions are involved in the present invention, they all have the same meaning, and the selection range of substituents is as shown above and will not be repeated one by one.

[0063] The present invention provides a novel organic electroluminescent device, wherein a mixture of ETL1 and ETL2 is selected as the main material of an electron transport layer, and then a third electron transport material is doped, wherein the third electron transport material is LiQ. The electron transport layer formed by the technical solution of the present invention can balance the injection of carriers in the device and enhance the stability of the electron transport layer, thereby reducing the driving voltage of the device, and improving the luminous efficiency and the life of the device.

[0064] Preferably, in the electron transport layer, the molar mass ratio of ETL1 and ETL2 is 1:9 to 9:1, for example, 1:9, 2:8, 3:7, 4:6, 6:4, 7:3, 8:2, 9:1, etc., and preferably the molar mass ratio of ETL1 and ETL2 is 3:7 to 7:3.

[0065] Preferably, the doping concentration of LiQ in the electron transport layer in the mixture comprising ETL1 and ETL2 is 10% to 200% (molar mass percentage), for example, 10%, 50%, 80%, 100%, 120%, 150%, 200%, etc., preferably 80% to 120%.

[0066] Preferably, the total thickness of the electron transport layer is 15 nm-35 nm, for example, 15 nm, 20 nm, 25 nm, 28 nm, 30 nm, 35 nm, etc. Preferably, the total thickness of the electron transport layer is 25 nm-30 nm.

[0067] Preferably, the specific compounds selected by ETL1 and ETL2 have The difference in evaporation temperature at the evaporation rate is within 20° C. In this preferred embodiment, the difference in evaporation temperature of the selected compounds ETL1 and ETL2 is small, which can ensure that the two materials ETL1 and ETL2 can be premixed, which has the advantage of reducing production costs.

[0068] In the embodiment of the present invention, ETL1 preferably uses compound D5, and ETL2 preferably uses compound C35. The combination of the two is used as the main material in the electron transport layer. The evaporation temperatures are 220°C and 218°C, respectively, with a difference of less than 20°C. The preparation process adopts a process of premixing followed by co-evaporation, which has the beneficial effects of simple process and low cost.

[0069] In the present invention, the electron blocking layer further includes a guest material LiQ, and its structure is as follows:

[0070]

[0071] Preferably, the organic functional layer further includes a hole injection layer, a hole transport layer and an electron injection layer.

[0072] The organic electroluminescent device of the present invention is prepared by vacuum evaporation, and can also be prepared by other methods, not limited to vacuum deposition. The present invention is described only by using the device prepared by vacuum deposition.

[0073] The preparation method includes substrate cleaning, drying, pretreatment, cavity entry, and sequential vacuum deposition of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer (electron injection layer), a cathode, and a light extraction layer.

[0074] Among them, the substrate is a rigid substrate or a flexible substrate. The rigid substrate includes a glass substrate, a Si substrate, etc., and the flexible substrate includes a polyvinyl alcohol (PVA) film, a polyimide (PD) film, a polyester (PET) film, etc.; the substrate of the present invention is preferably a rigid glass substrate.

[0075] The anode may preferably be a conductive compound, alloy, metal, or a mixture of such materials having a large work function. Inorganic materials may be used, including metals or metal oxides, laminates formed by alternating metals and metals or metals and non-metals, etc. Metal oxides include indium tin oxide (ITO), zinc oxide (ZnO), indium zinc oxide (IZO), tin oxide (SnO), etc. Metals include gold, silver, copper, aluminum, etc. having a relatively high work function; the anode of the present invention is preferably ITO.

[0076] The hole injection layer can be a single compound material or a combination of multiple compounds. For example, the hole injection layer can use one or more compounds of HT-1 to HT-51, or one or more compounds of HI-1 to HI-3; or one or more compounds of HT-1 to HT-51 can be doped with one or more compounds of HI-1 to HI-3.

[0077]

[0078] The material of the hole transport layer can be selected from, but not limited to, phthalocyanine derivatives such as CuPc, conductive polymers or polymers containing conductive dopants such as polyphenylene ethylene, polyaniline / dodecylbenzenesulfonic acid (Pani / DBSA), poly(3,4-ethylenedioxythiophene) / poly(4-styrenesulfonate) (PEDOT / PSS), polyaniline / camphorsulfonic acid (Pani / CSA), polyaniline / poly(4-styrenesulfonate) (Pani / PSS), aromatic amine derivatives such as the compounds shown in HT-1 to HT-51 below; or any combination thereof.

[0079]

[0080]

[0081]

[0082]

[0083] The light-emitting layer includes a light-emitting dye (i.e., dopant) that can emit light of different wavelength spectra, and may also include a host material (Host). The light-emitting layer may be a monochrome light-emitting layer that emits a single color such as red, green, and blue. A plurality of monochrome light-emitting layers of different colors may be arranged in a plane according to a pixel pattern, or may be stacked together to form a color light-emitting layer. When light-emitting layers of different colors are stacked together, they may be separated from each other or may be connected to each other. The light-emitting layer may also be a single color light-emitting layer that can simultaneously emit different colors such as red, green, and blue.

[0084] According to different technologies, the light-emitting layer material can be made of different materials such as fluorescent electroluminescent materials, phosphorescent electroluminescent materials, and thermally activated delayed fluorescent materials. In an OLED device, a single light-emitting technology can be used, or a combination of multiple different light-emitting technologies can be used. These different light-emitting materials classified by technology can emit light of the same color or different colors.

[0085] The main material of the blue light emitting layer is selected from any one or a combination of at least two of the following compounds BFH-1 to BFH-17:

[0086]

[0087] The guest material of the blue light emitting layer is selected from any one or a combination of at least two of the compounds shown in BFD-1 to BFD-24 below:

[0088]

[0089]

[0090] The phosphorescent light emitting layer host material is selected from any one or a combination of at least two of the following compounds PH-1 to PH-85:

[0091]

[0092]

[0093]

[0094]

[0095] The guest material of the phosphorescent light emitting layer, the green light is selected from any one or a combination of at least two of the compounds shown in the following GPD-1 to GPD-47, and the red light is selected from any one or a combination of at least two of the compounds shown in the following RPD-1 to RPD-28:

[0096]

[0097]

[0098]

[0099] The cathode is a metal such as a magnesium-silver mixture, LiF / Al, ITO, a metal mixture, an oxide, etc., and LiF / Al is preferred in the present invention.

[0100] Compared with the prior art, the present invention has the following beneficial effects:

[0101] The present invention provides a novel organic electroluminescent device. A combination of electron transport materials represented by formula (1) and formula (2) is selected as the main material in the electron transport layer, which can exert a performance superior to that of the combination when used alone. The synergistic effect of the two can further balance the carriers and enhance the stability of the electron transport layer, thereby improving the luminous efficiency of the device, reducing the driving voltage, and prolonging the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0102] Figure 1 It is a schematic diagram of the structure of the organic electroluminescent device provided in Example 1 of the present invention, wherein 1 is anode, 2 is hole injection layer, 3 is hole transport layer, 4 is light-emitting layer, 5 is electron transport layer, 6 is electron injection layer, and 7 is cathode. DETAILED DESCRIPTION

[0103] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0104] The compounds of general formula (1) used in the following examples are prepared by the method disclosed in patent application No. 201811081491.1. Those skilled in the art can also prepare them by other existing technologies, and the preparation method will not be described in detail in the present invention.

[0105] The compounds of general formula (2) used in the following examples are prepared by the method disclosed in patent application No. 201910014144.5. Those skilled in the art can also prepare them by other existing technologies, and the preparation method will not be described in detail in the present invention.

[0106] Example 1

[0107] This embodiment provides an organic electroluminescent device. The structure of the organic electroluminescent device is as shown in the attached specification. Figure 1 As shown, it specifically includes an anode 1, a hole injection layer (HIL layer) 2, a hole transport layer (HTL layer) 3, a light emitting layer (EML layer) 4, an electron transport layer (ETL layer) 5, an electron injection layer (EIL layer) 6 and a cathode 7.

[0108] The preparation method of the organic electroluminescent device is as follows:

[0109] On an anode glass substrate with a film thickness of 150 nm formed of indium tin oxide (ITO) / Ag / indium tin oxide (ITO), a vacuum evaporation method was used. When the vacuum degree reached 2×10 -4 Each film layer was deposited at 100 Pa. First, a hole injection layer, i.e., a HT-4:3% HI-3 film (3% refers to the doping ratio of HI-3 in the hole injection layer) was formed on ITO. The evaporation rate ratio of HT-4 to HI-3 was 1:0.03, and the evaporation rate of HT-4 was / second, with a total thickness of 10nm; then 60nm of HT-4 was deposited as a hole transport layer at an evaporation rate of / sec. On the hole transport layer HT-4, the light-emitting layer is evaporated. BFH-4:3% BFD-4 (3% refers to the doping ratio of the dye in the light-emitting layer) is co-evaporated from different evaporation sources as a 20nm blue light-emitting layer. The evaporation rate ratio is 1:0.03, and the evaporation rate of BFH-4 is / second; then deposit 25nm of D5 and C35 mixture: 100% LiQ as the electron transport layer, where 100% refers to the molar mass percentage of the guest material and the host material (a mixture of the first electron transport material and the second electron transport material) in the electron transport layer, the molar mass ratio of D5:C35 in the D5 and C35 mixture is 6:4, and the evaporation rate of the D5 and C35 mixture is / second; then deposit 1nm of LiF as an electron injection layer, the evaporation rate is / sec; the Al layer with a thickness of 150nm serves as the cathode of the device.

[0110] Example 2

[0111] The only difference from Example 1 is that the molar mass ratio of D5:C35 in the D5:C35 mixture is 1:9.

[0112] Example 3

[0113] The only difference from Example 1 is that the molar mass ratio of D5:C35 in the D5:C35 mixture is 2:8.

[0114] Example 4

[0115] The only difference from Example 1 is that the molar mass ratio of D5:C35 in the D5:C35 mixture is 3:7.

[0116] Example 5

[0117] The only difference from Example 1 is that the molar mass ratio of D5:C35 in the D5:C35 mixture is 4:6.

[0118] Example 6

[0119] The only difference from Example 1 is that the molar mass ratio of D5:C35 in the D5:C35 mixture is 7:3.

[0120] Example 7

[0121] The only difference from Example 1 is that the molar mass ratio of D5:C35 in the D5 / C35 mixture is 8:2.

[0122] Example 8

[0123] The only difference from Example 1 is that the molar mass ratio of D5:C35 in the D5:C35 mixture is 9:1.

[0124] Example 9

[0125] The only difference from Example 1 is that the molar mass percentage of the mixture of guest LiQ, D5 and C35 in the electron transport layer is 10%.

[0126] Example 10

[0127] The only difference from Example 1 is that the molar mass percentage of the mixture of guest LiQ, D5 and C35 in the electron transport layer is 50%.

[0128] Embodiment 11

[0129] The only difference from Example 1 is that the molar mass percentage of the mixture of guest LiQ, D5 and C35 in the electron transport layer is 80%.

[0130] Example 12

[0131] The only difference from Example 1 is that the molar mass percentage of the mixture of guest LiQ, D5 and C35 in the electron transport layer is 120%.

[0132] Embodiment 13

[0133] The only difference from Example 1 is that the molar mass percentage of the mixture of guest LiQ, D5 and C35 in the electron transport layer is 150%.

[0134] Embodiment 14

[0135] The only difference from Example 1 is that the molar mass percentage of the mixture of guest LiQ, D5 and C35 in the electron transport layer is 200%.

[0136] Embodiment 15

[0137] The only difference from Example 1 is that the total thickness of the electron transport layer is 15 nm.

[0138] Example 16

[0139] The only difference from Example 1 is that the total thickness of the electron transport layer is 20 nm.

[0140] Embodiment 17

[0141] The only difference from Example 1 is that the total thickness of the electron transport layer is 28 nm.

[0142] Embodiment 18

[0143] The only difference from Example 1 is that the total thickness of the electron transport layer is 30 nm.

[0144] Embodiment 19

[0145] The only difference from Example 1 is that the total thickness of the electron transport layer is 35 nm.

[0146] Embodiment 20

[0147] The only difference from Example 1 is that the main material in the electron transport layer is replaced by a mixture of D6 and C35.

[0148] Embodiment 21

[0149] The only difference from Example 1 is that the main material in the electron transport layer is replaced by a mixture of D5 and C85.

[0150] Embodiment 22

[0151] The only difference from Example 1 is that the main material in the electron transport layer is replaced by a mixture of D9 and C85.

[0152] Embodiment 23

[0153] The only difference from Example 1 is that the main material in the electron transport layer is replaced by a mixture of D14 and C121.

[0154] Embodiment 24

[0155] The only difference from Example 1 is that the main material in the electron transport layer is replaced by a mixture of D18 and C162.

[0156] Embodiment 25

[0157] The only difference from Example 1 is that the main material in the electron transport layer is replaced by a mixture of D21 and C35.

[0158] Embodiment 26

[0159] The only difference from Example 1 is that the main material in the electron transport layer is replaced by a mixture of D62 and C85.

[0160] Embodiment 27

[0161] The only difference from Example 1 is that the molar mass percentage of the mixture of guest LiQ, D5 and C35 in the electron transport layer is 5%.

[0162] Embodiment 28

[0163] The only difference from Example 1 is that the molar mass percentage of the mixture of guest LiQ, D5 and C35 in the electron transport layer is 250%.

[0164] Embodiment 29

[0165] The only difference from Example 1 is that the total thickness of the electron transport layer is 10 nm.

[0166] Embodiment 30

[0167] The only difference from Example 1 is that the total thickness of the electron transport layer is 40 nm.

[0168] Comparative Example 1

[0169] The only difference from Example 1 is that the main material in the electron transport layer is replaced with the prior art compound ET-11, and the structural formula of ET-11 is as follows:

[0170]

[0171] Comparative Example 2

[0172] The only difference from Example 1 is that the main material in the electron transport layer is replaced by a mixture of the prior art compound E-11 and compound C35.

[0173] Comparative Example 3

[0174] The only difference from Example 1 is that the main material in the electron transport layer is replaced with D5.

[0175] Comparative Example 4

[0176] The only difference from Example 1 is that the main material in the electron transport layer is replaced with C35.

[0177] Comparative Example 5

[0178] The only difference from Example 1 is that the molar mass ratio of D5:C35 in the mixture of D5 and C35 is 10:1.

[0179] Comparative Example 6

[0180] The only difference from Example 1 is that the molar mass ratio of D5:C35 in the mixture of D5 and C35 is 1:10.

[0181] Performance Testing

[0182] (1) Under the same brightness, the driving voltage and current efficiency of the organic electroluminescent devices prepared in the examples and comparative examples and the life of the devices were measured using a PR 750 photoradiometer, ST-86LA luminance meter (Beijing Normal University Photoelectric Instrument Factory) and Keithley 4200 test system. Specifically, the voltage was increased at a rate of 0.1 V per second, and the brightness of the organic electroluminescent device was measured at 1000 cd / m 2 The voltage at this time is the driving voltage (V), and the current density at this time is measured at the same time; the ratio of brightness to current density is the current efficiency (CE, cd / A);

[0183] (2) The life test of LT97 is as follows: using ST-86LA luminance meter (Beijing Normal University Optoelectronic Instrument Factory) at 3000 cd / m 2 , under the brightness, maintaining a constant current, measuring the time when the brightness of the organic electroluminescent device drops to 97% of the initial brightness. The data given in Table 1 are relative values ​​of the lifespan of the embodiments or comparative examples compared with Example 1.

[0184] The test results are shown in Table 1.

[0185] Table 1:

[0186]

[0187]

[0188]

[0189] As can be seen from Table 1, compared with the technical solution of the prior art using one main material of the electron transport layer, the device prepared by mixing two types of materials, ETL1 and ETL2, as the main material of the electron transport layer and doping LiQ in Examples 1-30 of the present invention can reduce the driving voltage, improve the current efficiency, and significantly improve the lifespan. At the same time, it can reduce the process cost and improve the finished product yield of the OLED display device. Furthermore, from the parallel comparison of the different doping ratios and different electron transport layer thickness parameters set in Examples 1-30, in the technical solution of the present invention, the preferred molar mass percentage of LiQ to the mixture containing ETL1 and ETL2 is 10% to 200%, and the most preferred is 80% to 120%, and the total thickness of the electron transport layer is preferably 15nm-35nm, and the most preferred is 25nm-30nm.

[0190] The applicant declares that the present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An organic electroluminescent device, characterized in that: The organic electroluminescent device comprises a first electrode, a second electrode and an organic layer located between the first electrode and the second electrode, wherein the organic layer comprises a light-emitting layer and an electron transport layer, wherein the electron transport layer comprises a mixture of a first electron transport material ETL1 and a second electron transport material ETL2, wherein the molar mass ratio of the ETL1 to the ETL2 is 1:9-9:1, and the ETL1 is selected from a compound having a structure as shown in formula (1): In formula (1), Ar1 is selected from substituted or unsubstituted C12-C30 aryl groups, substituted or unsubstituted C8-C30 heteroaryl groups, and Ar1 is a fused aryl group or fused heteroaryl group having a large conjugated structure, wherein the fused aryl group or fused heteroaryl group having a large conjugated structure is a conjugated system having 14 to 24 conjugated π electrons; R a ~R b Each is independently selected from one of hydrogen, C1-C12 aliphatic hydrocarbon group, C1-C12 aliphatic hydrocarbonoxy group, halogen, cyano group, nitro group, hydroxyl group, C1-C30 silane group, amino group, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C3-C30 heteroaryl group; R 1 ~R 4 Each is independently selected from hydrogen, C1-C12 aliphatic hydrocarbon group, C1-C12 aliphatic hydrocarbonoxy group, halogen, cyano, nitro, hydroxyl, C1-C30 silane group, amino, substituted or unsubstituted C6-C30 aryl group, substituted or unsubstituted C3-C30 heteroaryl group, R 1 and R 2 Can be interconnected to form a ring, R 3 and R 2 Can be interconnected to form a ring, R 3 and R 4 Can be interconnected to form a ring; The above Ar1, R a ~R b , R 1 ~R 4 When there is a substituent, it means that it is substituted by one or more substituents selected from halogen, C1-C12 aliphatic hydrocarbon group, C1-C12 aliphatic hydrocarbonoxy group, C6-C12 aryl group, C3-C12 heteroaryl group, cyano group, and hydroxyl group; The ETL2 is selected from the compound having the structure shown in formula (2): In formula (2), L is selected from substituted or unsubstituted C6-C30 arylene groups; R 5 , R 6 and R 7 Each is independently selected from one of hydrogen, cyano, substituted or unsubstituted C1-C10 alkyl or cycloalkyl, substituted or unsubstituted C6-C30 aryl, and substituted or unsubstituted C3-C30 heteroaryl; Ar2 is a substituent group represented by the following formula (A): In formula (A), X 1 ~X 6 Each is independently selected from a nitrogen atom, CH or CR, and at least one of them is a nitrogen atom, and each R is independently selected from one of a C1-C10 alkyl group, a C1-C10 alkoxy group, a substituted or unsubstituted C6-C30 aryl group, and a substituted or unsubstituted C3-C30 heteroaryl group; When the above L, R, X 1 ~X 6 , R 5 , R 6 and R 7 When there are substituents, the substituents are independently selected from one of halogen, C1-C10 alkyl or cycloalkyl, C2-C10 alkenyl, C1-C6 alkoxy or thioalkoxy groups, C6-C30 aryl, and C3-C30 heteroaryl.

2. The organic electroluminescent device according to claim 1, characterized in that: The molar mass ratio of ETL1 to ETL2 is 3:7-7:

3.

3. The organic electroluminescent device according to claim 1, characterized in that: When L is selected from a substituted arylene group, the substituent is a C3-C30 heteroaryl group.

4. The organic electroluminescent device according to claim 1, characterized in that: In formula (1): The R a ~R b Each is independently selected from one of halogen, cyano, nitro, hydroxyl, substituted or unsubstituted C6-C30 aryl, and substituted or unsubstituted C3-C30 heteroaryl.

5. The organic electroluminescent device according to claim 1, characterized in that: The Ar1 is a conjugated system having 14 to 18 conjugated π electrons.

6. The organic electroluminescent device according to claim 1, characterized in that: In formula (1): The Ar1 is selected from phenanthryl, triphenylene, fluoranthene, anthracene, pyrene, dihydropyrene, anise, perylene, fluoranthene, benzanthracene, triphenylene, tetracene, pentacene, benzopyrene, benzofuran, isobenzofuran, benzothiophene, isobenzothiophene, quinoline, isoquinoline, acridine, phenanthridine, benzo-5,6-quinoline, benzo-6,7-quinoline, benzo-7,8-quinoline, phenothiazine, phenazine, indazole, benzimidazole, naphthoimidazole, phenanthroimidazole, pyrazole, benzopyrazole, pyridopyridine, pyridoimidazole, pyrazinoimidazole, quinoxalinoimidazole, benzoxazole, naphthoxidazole, anthraxidazole, phenanthroxidazole, benzothiazole, benzopyridazine, pyrimidine, benzopyrimidine, quinoxaline, phenazine, naphthyridine, azacarbazole, benzocarboline, phenanthroline, benzotriazole, purine, pteridine, indolizine, benzothiadiazole or a combination of two thereof; R a ~R b One or a combination of two selected from phenyl, naphthyl, biphenyl, fluorenyl, pyridyl, furanyl, thienyl, diphenylpropanefuranyl, and dibenzothienyl; R 1 ~R 4 Each is independently selected from hydrogen, methyl, ethyl, isopropyl, tert-butyl, phenyl, biphenyl, terphenyl, naphthyl, anthracenyl, phenanthrenyl, indenyl, fluorenyl, fluoranthenyl, triphenylene, pyrenyl, peryl, The invention further comprises the following: 1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 51, 52, 53, 54, 55, 56, 57, 58, 59, 61, 62, 63, 64, 65, 67, 68, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92 7. The organic electroluminescent device according to claim 1, characterized in that: In formula (1), Ar1 is selected from one of the following groups: "*" represents the connection site, and the connection bond of the substituent is represented by "—" crossing the ring structure, which means that the connection site is at any bonding position on the ring structure. The hydrogen atoms on these groups can be substituted, and the substituents are selected from halogen, C1-C12 aliphatic hydrocarbon groups, C1-C12 aliphatic hydrocarbon oxide groups, C6-C12 aryl groups, C3-C12 heteroaryl groups, cyano groups, and hydroxyl groups.

8. The organic electroluminescent device according to claim 1, characterized in that: The ETL1 is selected from any one of the compounds shown below:

9. The organic electroluminescent device according to claim 1, characterized in that: The ETL2 is selected from compounds having structures shown in formula (2-1), (2-2) or (2-3): Among them, R 5 , R 6 , R 7 and L are defined the same as in formula (2); R 8 One selected from hydrogen, cyano, substituted or unsubstituted C1-C10 alkyl, C1-C10 alkoxy, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C3-C30 heteroaryl; m is an integer value from 0 to 2.

10. An organic electroluminescent device, comprising a first electrode, a second electrode and an organic layer located between the first electrode and the second electrode, wherein the organic layer comprises a light-emitting layer and an electron transport layer, wherein the electron transport layer comprises a mixture of a first electron transport material ETL1 and a second electron transport material ETL2, wherein the molar mass ratio of ETL1 to ETL2 is 1:9-9:1, wherein ETL1 is selected from the compound having the structure shown in formula (1) as claimed in claim 1, and wherein ETL2 is selected from any one of the following compounds:

11. The organic electroluminescent device according to any one of claims 1 to 10, characterized in that: The electron transport layer further includes a third electron transport material, the third electron transport material is LiQ, and the molar mass percentage of the mixture of the third electron transport material and the material selected from ETL1 and ETL2 is 10% to 200%.

12. The organic electroluminescent device according to claim 11, characterized in that: The molar mass percentage of the mixture of the third electron transport material and the selected from ETL1 and ETL2 is 80% to 120%.

13. The organic electroluminescent device according to any one of claims 1 to 10, characterized in that: The total thickness of the electron transport layer is 15nm-35nm.

14. The organic electroluminescent device according to claim 13, characterized in that: The total thickness of the electron transport layer is 25nm-30nm.

15. The organic electroluminescent device according to claim 1, characterized in that: The organic layer further includes at least one of a hole injection layer, a hole transport layer and an electron injection layer.

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