An organic electroluminescent device

Abstract

An organic electroluminescent device, the organic electroluminescent device comprising: a first electrode, a second electrode facing the first electrode, a light-emitting layer between the first electrode and the second electrode, and a covering layer on the electrode on the side where light is emitted, wherein a hole transport region is provided between the anode and the light-emitting layer, an electron transport region is provided between the cathode and the light-emitting layer, the electron transport region comprises an electron transport layer, the electron transport layer comprises a first electron transport compound and a second electron transport compound, the structure of the first electron transport compound is shown in general formula (1); the second electron transport compound is a metal Li complex, as shown in any one of general formulas (2) to (5). The present invention adopts a combination of a first electron transport material and a second electron transport material metal Li complex, which can effectively regulate the injection of electrons from the cathode into the light-emitting layer or the hole blocking layer, which can not only reduce the device voltage, but also improve the device efficiency and life.

Description

Technical Field

[0001] The present invention relates to an organic electroluminescent device, and in particular to an application of a combination of a first electron transport compound and a second electron transport compound in an electron transport layer in a blue organic electroluminescent device. Background Art

[0002] Organic light emitting diode (OLED) device technology can be used to manufacture new display products and new lighting products. It is expected to replace existing liquid crystal displays and fluorescent lighting, and has a wide range of applications. OLED light-emitting devices are like sandwich structures, including electrode material films and organic functional materials sandwiched between different electrode film layers. Various functional materials are superimposed on each other according to their uses to form OLED light-emitting devices. As a current device, when voltage is applied to the electrodes at both ends of the OLED light-emitting device and the electric field acts on the positive and negative charges in the organic layer functional material film layer, the positive and negative charges are further compounded in the light-emitting layer, generating OLED electroluminescence.

[0003] The OLED optoelectronic functional material film layer that constitutes the OLED device includes at least two layers of structure. The OLED device structure used in the industry includes multiple film layers such as hole injection layer, hole transport layer, electron blocking layer, light-emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc. That is to say, the optoelectronic functional materials used in OLED devices include at least hole injection materials, hole transport materials, light-emitting materials, electron transport materials, etc., and the material types and matching forms are rich and diverse.

[0004] Factors affecting the efficiency and life of organic electroluminescent devices include: i) whether the electrons and holes in the light-emitting layer are balanced; ii) whether the emission regions in the light-emitting layer are widely (or uniformly) distributed in the light-emitting layer, rather than focusing on the hole transport layer or the electron transport layer. It has been found that when only one type (kind) of material is used as an electron transport layer, all the listed factors cannot be met. However, when a) at least two types (kinds) of different materials are used as electron transport layers and b) the characteristics of the substituents of the at least two types (kinds) of different materials are different from each other, all the listed factors can be met, thereby improving the efficiency and life of the organic electroluminescent device.

[0005] For the device life, the heat resistance and film stability of the material are also important. Materials with low heat resistance are not only prone to decomposition during material evaporation, but also thermal decomposition caused by the heat generated by the device during operation, leading to material degradation. In the case of poor phase stability of the material film, the material will also undergo thin film crystallization in a short period of time, resulting in direct layer separation of the organic film layer and device degradation. Therefore, the materials used are required to have high heat resistance and good film stability.

[0006] Patent CN107342366A and Patent CN105593336A disclose that triazine derivatives and 8-hydroxyquinoline lithium are vacuum deposited in a ratio of 1:1 as an electron transport layer, and then LiF is deposited on the electron transport layer. The driving voltage and efficiency improvement effect of the device is not very obvious, and Patent CN107342366A does not involve the device life. Patent CN105593336A has a poor device life. Compared with the prior art, the device voltage is large and the device luminous efficiency is low. Traditional inorganic lithium compounds, such as lithium fluoride, lithium carbonate and lithium oxide, have high material evaporation temperatures and are easily decomposed by water and oxygen. More importantly, inorganic lithium compounds are easily separated from organic matter, resulting in a reduced device life.

[0007] In order to improve the efficiency and life of organic electroluminescent devices, it is necessary to improve the device structure and develop new materials to meet the various requirements of future flat panel displays. Therefore, it is necessary to continuously develop materials with better performance for organic electroluminescent devices. Summary of the invention

[0008] In view of the above problems existing in the prior art, the present invention provides an organic electroluminescent device. The present invention adopts the combination of the first electron transport material and the second electron transport material metal Li complex described in the general formula (1), which can effectively regulate the injection of electrons from the cathode into the light-emitting layer or the hole blocking layer, and can not only reduce the device voltage, but also improve the device efficiency and life.

[0009] The technical solution of the present invention is as follows:

[0010] An organic electroluminescent device, comprising: a first electrode, a second electrode facing the first electrode, a light-emitting layer between the first electrode and the second electrode, and a covering layer on the electrode on the side where light is emitted; if the first electrode is an anode, the second electrode is a cathode; if the first electrode is a cathode, the second electrode is an anode; wherein a hole transport region is provided between the anode and the light-emitting layer, an electron transport region is provided between the cathode and the light-emitting layer, the electron transport region comprises an electron transport layer, wherein the electron transport layer comprises a first electron transport compound and a second electron transport compound, and the structure of the first electron transport compound is as shown in general formula (1):

[0011]

[0012] In the general formula (1), Ar 1 ,Ar 2 are independently substituted or unsubstituted C 6 -C 30 Aryl, substituted or unsubstituted C 3 -C 30 any one of the heteroaryl groups; L represents any one of a substituted or unsubstituted phenylene group, a substituted or unsubstituted biphenylene group, a substituted or unsubstituted naphthylene group, or a substituted or unsubstituted pyridylene group;

[0013] Ring A and Ring B are independently any one of substituted or unsubstituted phenyl and substituted or unsubstituted naphthyl, and Ring A and Ring B are not both phenyl;

[0014] The second electron transport compound is a metal Li complex, and its structure is shown in any one of the general formulas (2), (3), (4) and (5):

[0015]

[0016] In the general formula (2), the general formula (3), the general formula (4) and the general formula (5), R 1 ~R 11 are independently represented by hydrogen, protium, deuterium, tritium, C 1 -C 20 Alkyl, substituted or unsubstituted C 6 -C 30 Aryl, substituted or unsubstituted C 3 -C 30 One of the heteroaryl groups of 1 ~R 11 Two adjacent groups in the 6 -C 30 Aryl or C 3 -C 30 heteroaryl;

[0017] Ar a ,Ar b are independently substituted or unsubstituted C 6 -C 30 Aryl, substituted or unsubstituted C 3 -C 30 Any of the heteroaryl groups of d , where R d Represented by hydrogen atoms, deuterium atoms, substituted or unsubstituted C 6 -C30 Aryl, substituted or unsubstituted C 3 -C 30 One of the heteroaryl groups; two adjacent R d It can also bond to form C 6 -C 30 Aryl or C 3 -C 30 heteroaryl;

[0018] The substituents for the substituent groups are selected from one or more of protium, deuterium, tritium, cyano, fluorine atoms, methyl, ethyl, isopropyl, tert-butyl, anthracenyl, phenyl, pyridyl, and biphenyl;

[0019] The heteroatom in the heteroaryl group is selected from one or more of an oxygen atom, a sulfur atom and a nitrogen atom.

[0020] In a preferred embodiment, the electron transport layer is located in direct contact with the light-emitting layer; Ar 1 ,Ar 2 R is independently substituted or unsubstituted phenyl, substituted or unsubstituted biphenyl, substituted or unsubstituted pyridyl, substituted or unsubstituted naphthyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted naphthobenzofuranyl, substituted or unsubstituted quinolyl, substituted or unsubstituted pyrimidinyl, substituted or unsubstituted azadibenzofuranyl; 1 ~R 11 each independently represents protium, deuterium, tritium, methyl, ethyl, isopropyl, tert-butyl, substituted or unsubstituted phenyl, substituted or unsubstituted biphenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted terphenyl, substituted or unsubstituted anthracenyl, substituted or unsubstituted phenanthryl, substituted or unsubstituted pyridyl, substituted or unsubstituted pyridazinyl, substituted or unsubstituted triazinyl, substituted or unsubstituted carbazolinyl, substituted or unsubstituted pyrimidinyl, substituted or unsubstituted pyrazinyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted carbazolyl, substituted or unsubstituted N-phenylcarbazolyl, substituted or unsubstituted dibenzothiophenyl, substituted or unsubstituted quinolyl, substituted or unsubstituted isoquinolyl, substituted or unsubstituted naphthyridinyl, substituted or unsubstituted quinoxalinyl, substituted or unsubstituted cinnolinyl or substituted or unsubstituted quinazolinyl; Ar a ,Ar b R is independently a substituted or unsubstituted phenyl, a substituted or unsubstituted biphenyl, a substituted or unsubstituted naphthyl, a substituted or unsubstituted pyridyl, a substituted or unsubstituted pyridazinyl, a substituted or unsubstituted quinolyl, a substituted or unsubstituted triazinyl, a substituted or unsubstituted benzofuranyl, a substituted or unsubstituted dibenzofuranyl, a substituted or unsubstituted carbazolyl, or a substituted or unsubstituted carbazoline group; drepresented by a hydrogen atom, a deuterium atom, a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted pyridazinyl group, a substituted or unsubstituted quinolyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted benzofuranyl group, a substituted or unsubstituted dibenzofuranyl group, a substituted or unsubstituted carbazolyl group, or a substituted or unsubstituted carbazoline group;

[0021] The substituent for the substituent group is selected from one or more of protium, deuterium, tritium, cyano, fluorine atom, methyl, ethyl, isopropyl, tert-butyl, anthracenyl, phenyl, pyridyl, biphenyl.

[0022] In a preferred embodiment, an additional hole blocking layer is present between the electron transport layer and the light-emitting layer.

[0023] In a preferred embodiment, the structure of the first electron transport compound is any one of the following structures:

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030] Preferably, the structure of the second electron transport compound is any one of the following structures:

[0031]

[0032]

[0033] In a preferred embodiment, the weight ratio of the first electron transport compound to the second electron transport compound is 1:10 to 10:1, preferably 1:9 to 9:1, more preferably 2:8 to 8:2, and even more preferably 3:7 to 7:3.

[0034] In a preferred embodiment, the thickness of the electron transport layer is 10-80 nm, preferably 20-60 nm, and more preferably 25-45 nm.

[0035] A method for preparing the organic electroluminescent device, the method comprising laminating a first electrode, an organic functional material layer and a second electrode on a substrate from bottom to top, wherein the organic functional material layer consists of a hole transport region, a light-emitting layer and an electron transport region, and the lamination is performed by vacuum evaporation at a temperature of 100-500°C for 10 -8 -10 -2 Torr vacuum and at a rate of .

[0036] A display device comprises the organic electroluminescent device.

[0037] The beneficial technical effects of the present invention are:

[0038] 1. The general formula (1) of the present invention contains a triazine group and has excellent electron transport ability. When the compound described in the general formula (1) is used in the organic material layer (especially the electron transport layer and the electron injection layer) of the organic light-emitting device, the device can have the characteristics of long life and high efficiency;

[0039] 2. The compound described in the general formula (1) of the present invention has a deeper HOMO energy level (greater than 6 eV), which can effectively block holes from the light-emitting layer; the general formula (1) of the present invention has a carbazole derivative group, which can have a higher triplet energy, can play a role in improving the luminous efficiency, and can provide a device with a long life by enhancing the stability of the device;

[0040] 3. The LUMO energy level of the compound described in the general formula (1) is greater than or equal to 3.0 eV, while the LUMO energy level of the compound described in the general formula (2) is smaller. When the first electron transport material and the second electron transport material selected from the general formula (1) are used in combination with the metal Li complex, the electrons injected from the cathode into the light-emitting layer or the hole blocking layer can be effectively regulated, which can not only reduce the device voltage, but also improve the device efficiency and life.

[0041] 4. The first electron transport compound of the present invention has a more negative LUMO energy level than the main material of the light-emitting layer, which can effectively avoid excessive electron injection into the light-emitting layer, reduce the exciton quenching effect, and help to improve the device service life.

[0042] 5. Furthermore, the first electron transport compound of the present invention has good electron mobility, which is beneficial to reduce the device driving voltage and improve the electron-hole recombination efficiency in the light-emitting layer; when combined with the second electron transport compound metal Li complex of the present invention, it can improve the device efficiency and life. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic structural diagram of an organic electroluminescent device according to one embodiment of the present invention.

[0044] Figure 1 In the figure, 1. substrate; 2. first electrode; 3. hole injection layer; 4. hole transport layer; 5. electron blocking layer; 6. light-emitting layer; 7. hole blocking layer; 8. electron transport layer; 9. electron injection layer; 10. second electrode; 11. covering layer; A. electron transport region; B. hole transport region.

[0045] Figure 2 It is a schematic structural diagram of an organic electroluminescent device according to one embodiment of the present invention.

[0046] Figure 2 In the figure, 1. substrate; 2. first electrode; 3. hole injection layer; 4. hole transport layer; 5. electron blocking layer; 6. light-emitting layer; 7. electron transport layer; 8. electron injection layer; 9. second electrode; 10. covering layer; A. electron transport region; B. hole transport region. DETAILED DESCRIPTION

[0047] In this application, unless otherwise specified, HOMO means the highest occupied orbital of a molecule, and LUMO means the lowest unoccupied orbital of a molecule. In addition, the "difference in HOMO energy levels" and "difference in LUMO energy levels" referred to in this specification mean the difference in the absolute value of each energy value. In addition, in the present invention, HOMO and LUMO energy levels are expressed in absolute values, and the comparison between energy levels is also a comparison of the absolute values ​​thereof. Those skilled in the art know that the larger the absolute value of an energy level, the lower the energy of the energy level.

[0048] The C used in this article 6-30 Aryl refers to a monovalent group including a carbocyclic aromatic system having 6 to 30 carbon atoms as ring atoms. 6-30 The arylene group refers to a divalent group including a carbocyclic aromatic system having 6 to 30 carbon atoms as ring atoms. 6-30 Non-limiting examples of aryl groups may include phenyl, biphenyl, phenanthryl, anthracenyl, terphenyl, naphthyl, and the like. 6-30 Non-limiting examples of the arylene group may include phenylene, biphenylene, phenanthrenyl, terphenylene, naphthylene, and the like. 6-30 Aryl and / or C 6-30 When the arylene group includes two or more rings, these rings may be fused to each other.

[0049] The C used in this article 3-30 The heteroaryl group refers to a monovalent group including a carbocyclic aromatic system having at least one heteroatom selected from N, O and S as a ring atom and 3 to 30 carbon atoms. 3-30The heteroarylene group refers to a divalent group including a carbocyclic aromatic system having at least one heteroatom selected from N, O and S as a ring-forming atom and 3 to 30 carbon atoms. 3-30 Non-limiting examples of heteroaryl groups may include pyridyl, dibenzofuranyl, benzoxazolyl, bisbenzoxazolyl, carbazolyl, N-phenylcarbazolyl, pyridazinyl, quinolyl, triazinyl, benzofuranyl, carbazolyl, carbazolinyl, pyrimidinyl, pyrazinyl, dibenzofuranyl, dibenzothiophenyl, quinolyl, isoquinolyl, triphenylene, naphthyridinyl, quinoxalinyl, cinnolinyl, or quinazolinyl, etc. 3-30 Non-limiting examples of heteroarylene groups may include divalent groups of the above groups. 3-30 Heteroaryl and C 3-30 When the heteroarylene group includes two or more rings, these rings may be fused to each other.

[0050] The C used in this article 1-20 The alkyl group refers to a monovalent group including a straight or branched chain alkyl group having 1 to 20 carbon atoms. 1-20 Non-limiting examples of alkyl groups may include methyl, ethyl, propyl, isopropyl, tert-butyl, pentyl, and the like.

[0051] Preferably, the present invention provides an organic electroluminescent device, which includes, from bottom to top, a substrate, a first electrode, an organic functional layer, a second electrode, and a covering layer, the covering layer being on the electrode on the side where light is emitted, wherein if the first electrode is a cathode, the second electrode is an anode; if the first electrode is an anode, the second electrode is a cathode, wherein the organic functional layer includes: a light-emitting layer, which is located between the anode and the cathode, and the light-emitting layer contains a main material and a doping material; a hole transport region, which is located between the anode and the light-emitting layer; and an electron transport region, which is located between the light-emitting layer and the cathode. Preferably, the hole transport region includes one or more of a hole injection layer, a hole transport layer, and an electron blocking layer. Preferably, the electron transport region includes one or more of a hole blocking layer, an electron transport layer, and an electron injection layer.

[0052] Preferably, if Figure 1 As shown, the organic electroluminescent device according to the present invention includes a substrate, a first electrode (anode), a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, a second electrode (cathode) and a covering layer in sequence.

[0053] Preferably, the organic electroluminescent device according to the present invention comprises, in sequence, a substrate, a first electrode (anode), a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer, a second electrode (cathode) and a covering layer.

[0054] In one embodiment of the present invention, the organic functional layer of the organic electroluminescent device includes a hole injection layer doped with P-type material, a hole transport layer, an electron blocking layer, a fluorescent light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer.

[0055] As the substrate of the organic electroluminescent device of the present invention, any substrate commonly used in organic electroluminescent devices can be used. Examples are transparent substrates such as glass or transparent plastic substrates; opaque substrates such as silicon substrates; flexible PI film substrates. Different substrates have different mechanical strengths, thermal stability, transparency, surface smoothness, and waterproofness. Depending on the properties of the substrate, its use direction is different. In the present invention, a transparent substrate is preferably used. The thickness of the substrate is not particularly limited.

[0056] A first electrode is formed on the substrate, and the first electrode and the second electrode may be opposite to each other. The first electrode may be an anode or a cathode. If the first electrode is an anode, the first electrode material is preferably a material with a high work function so that holes can be easily injected into the organic functional material layer. Non-limiting examples of the first electrode material include, but are not limited to, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO 2 ), zinc oxide (ZnO), magnesium (Mg), aluminum (Al), silver (Ag), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In) and magnesium-silver (Mg-Ag). The first electrode may have a single-layer structure or a multilayer structure including two or more layers. For example, the first electrode may have a three-layer structure of ITO / Ag / ITO, but is not limited thereto. In addition, the thickness of the first electrode depends on the material used, and is typically 50-500nm, preferably 70-300nm and more preferably 100-200nm.

[0057] The hole transport region may be disposed between the anode and the light emitting layer. The hole transport region may include a hole injection layer, a hole transport layer, and an electron blocking layer. For example, referring to Figure 1 The hole transport region may include a hole injection layer 3, a hole transport layer 4 and an electron blocking layer 5 which are sequentially arranged on the first electrode from bottom to top.

[0058] The hole injection layer structure is that the hole injection layer material is uniformly or non-uniformly dispersed in the hole transport layer, and the hole injection material can be, for example, a P dopant. The P dopant can be selected from at least one compound selected from the following: a quinone derivative, such as tetracyanoquinodimethane (TCNQ) or 2,3,5,6-tetrafluoro-tetracyano-1,4-benzoquinodimethane (F4-TCNQ); a metal oxide, such as tungsten oxide or molybdenum oxide; or a cyano-containing compound, such as the compounds P1, NDP and F4-TCNQ shown below:

[0059]

[0060] According to the present invention, P1 is preferably used as P dopant. The ratio of the hole transport layer to the P dopant used in the present invention is 99:1-70:30, preferably 99:1-85:15 and more preferably 97:3-87:13, based on mass.

[0061] The thickness of the hole injection layer of the present invention may be 1-100 nm, preferably 2-50 nm and more preferably 5-20 nm.

[0062] When the hole transport region includes a hole transport layer, the material of the hole transport layer is preferably a material with high hole mobility, which can transfer holes from the anode or the hole injection layer to the light-emitting layer. The hole transport material can be a phthalocyanine derivative, a triazole derivative, a triarylmethane derivative, a triarylamine derivative, an oxazole derivative, an oxadiazole derivative, a hydrazone derivative, a stilbene derivative, a pyridoline derivative, a polysilane derivative, an imidazole derivative, a phenylenediamine derivative, an amino-substituted quilone derivative, a styrene anthracene derivative, a styrene compound such as a styrene amine derivative, a fluorene derivative, a spirofluorene derivative, a silazane derivative, an aniline copolymer, a porphyrin compound, a carbazole derivative, a polyarylalkane derivative, polyphenylene vinyl and its derivatives, polythiophene and its derivatives, poly-N-vinylcarbazole derivatives, thiophene oligomers and other conductive polymer oligomers, aromatic tertiary amine compounds, styrene amination derivatives compounds, triamines, tetraamines, benzidines, propargyl diamine derivatives, p-phenylenediamine derivatives, m-phenylenediamine derivatives, 1,1'-bis(4-diarylaminophenyl)cyclohexane, 4,4'-bis(diarylamino)biphenyls, bis[4-(diarylamino)phenyl]methanes, 4,4"-bis(diarylamino)terphenyls, 4,4'"-bis(diarylamino)quaterphenyls, 4,4'-bis(diarylamino)diphenyl ethers, 4,4'-bis(diarylamino)diphenylsulfanes, bis[4-(diarylamino)phenyl]dimethylmethanes, bis[4-(diarylamino)phenyl]-bis(trifluoromethyl)methanes or 2,2-diphenylethylene compounds, etc.

[0063] The thickness of the hole transport layer of the present invention may be 5-200 nm, preferably 10-180 nm, and more preferably 20-150 nm.

[0064] The electron blocking layer requires that the triplet state (T1) energy level of the material is higher than the T1 energy level of the main material in the light-emitting layer, which can play a role in blocking the energy loss of the light-emitting layer material; the HOMO energy level of the electron blocking layer material is between the HOMO energy level of the hole transport layer material and the HOMO energy level of the main material of the light-emitting layer, which is conducive to the injection of holes from the positive electrode into the light-emitting layer. At the same time, the electron blocking layer material is required to have a high hole mobility, which is conducive to hole transport and reduces the power of the device; the LUMO energy level of the electron blocking layer material is higher than the LUMO energy level of the main material of the light-emitting layer, which plays a role in electron blocking, that is, the electron blocking layer material is required to have a wide bandgap width (Eg). The electron blocking layer materials that meet the above conditions can be triarylamine derivatives, fluorene derivatives, spirofluorene derivatives, dibenzofuran derivatives, carbazole derivatives, etc. Among them, triarylamine derivatives are preferred, such as N4,N4-bis([1,1'-biphenyl]-4-yl)-N4'-phenyl N4'-[1,1':4',1"-terphenyl]-4-yl-[1,1'-biphenyl]-4,4'-diamine; spirofluorene derivatives, such as N-([1,1'-diphenyl]-4-yl)-N-(9,9-dimethyl-9H-furan-2-yl)-9,9'-spirobifluorene-2-amine; dibenzofuran derivatives, such as N,N-di([1,1'-biphenyl]-4-yl)-3'-(dibenzo[b,d]furan-4-yl)-[1,1'-biphenyl]-4-amine, but are not limited to these.

[0065] According to the present invention, the thickness of the electron blocking layer may be 1-200 nm, preferably 5-150 nm, and more preferably 10-100 nm.

[0066] According to the present invention, a light-emitting layer may be provided on the hole transport region. The material of the light-emitting layer is a material that can emit visible light by receiving holes from the hole transport region and electrons from the electron transport region, respectively, and combining the received holes and electrons. The light-emitting layer may include a host material and a doping material. As the host material and guest material of the light-emitting layer of the organic electroluminescent device of the present invention, the host material may be one or a combination of two of anthracene derivatives, quinoxaline derivatives, triazine derivatives, xanthone derivatives, diphenyl ketone derivatives, carbazole derivatives, pyridine derivatives or pyrimidine derivatives. The guest material may be a pyrene derivative, a boron derivative, a chrysene derivative, a spirofluorene derivative, an iridium complex or a platinum complex. According to the present invention, the ratio of the host material to the guest material used is 99:1-70:30, preferably 99:1-85:15 and more preferably 97:3-87:13, based on mass.

[0067] The thickness of the light-emitting layer of the present invention may be 5-60 nm, preferably 10-50 nm, and more preferably 20-45 nm.

[0068] The hole blocking layer can be arranged on the light-emitting layer. The triplet state (T1) energy level of the hole blocking layer material is higher than the T1 energy level of the main material of the light-emitting layer, which can play a role in blocking the energy loss of the light-emitting layer material; the HOMO energy level of the material is lower than the HOMO energy level of the main material of the light-emitting layer, which plays a role in hole blocking. At the same time, the hole blocking layer material is required to have a high electron mobility, which is conducive to electron transmission and reduces the application power of the device; the hole blocking layer material that meets the above conditions can be triazine derivatives, azabenzene derivatives, etc. Among them, triazine derivatives are preferred; but not limited to this.

[0069] The thickness of the light-emitting layer of the present invention may be 5-60 nm, preferably 10-40 nm, and more preferably 10-30 nm.

[0070] The electron transport layer may be disposed on the hole blocking layer. The electron transport layer material is a material that easily receives electrons from the cathode and transfers the received electrons to the light-emitting layer. The electron transport layer is as described above.

[0071] As the first electron transport compound of the present invention, it is preferable to use the above-mentioned I-1, I-2, I-3, I-4, I-5, I-6, I-7, I-16, I-20, I-28, I-34, I-49, I-50, I-52, I-57, I-58, I-59, I-60, I-61, I-62, I-63, I-64, I-65, I-66, I-67, I-68, I-69, I-70, I-71, I-72, I-73, I-76, I-82, I-87, I-89, I-92, I-96, I-102, I-117, I-140, I-145, I-150, One or more of I-155 and I-164, more preferably the above-mentioned I-1, I-2, I-3, I-4, I-5, I-6, I-7, I-16, I-20, I-28, I-34, I-49, I-50, I-52, I-57, I-58, I-59, I-60, I-61, I- 62. One or more of I-63, I-64, I-65, I-66, I-67, I-68, I-69, I-70, I-71, I-72, I-73, I-76, I-82, I-87, I-89, I-140, I-145, I-150, I-155 and I-164. As the second electron transport compound of the present invention, it is preferred to use one or more of the above-mentioned II-1, II-2, II-3, II-4, II-5, II-6, II-19, II-22, II-25, II-28, II-30, II-39, II-40, II-44, II-45, II-47 and II-48, and it is more preferred to use one or more of the above-mentioned II-1, II-3, II-4, II-5, II-6, II-28, II-30, II-39, II-40, II-44, II-45, II-47 and II-48.

[0072] The electron transport layer of the present invention comprises a first electron transport compound and a second electron transport compound, and has a thickness of 10-80 nm, preferably 20-60 nm, and more preferably 25-45 nm.

[0073] In a preferred embodiment of the present invention, the electron injection layer material preferably has a low work function material metal Yb, so that electrons are easily injected into the organic functional material layer. The thickness of the electron injection layer of the present invention can be 0.1-5nm, preferably 0.5-3nm, and more preferably 0.8-1.5nm.

[0074] In a preferred embodiment of the present invention, a second electrode is disposed on the electron transport region.

[0075] In an embodiment of the present invention, the second electrode can be a cathode or an anode. In a preferred embodiment of the present invention, the second electrode is used as a cathode. The material used to form the cathode can be a material with a low work function, such as a metal, an alloy, a conductive compound or a mixture thereof. Non-limiting examples of the second electrode can include lithium (Li), ytterbium (Yb), magnesium (Mg), aluminum (Al), calcium (Ca), and aluminum-lithium (Al-Li), magnesium-indium (Mg-In) and magnesium-silver (Mg-Ag). The thickness of the second electrode depends on the material used, typically 5-100nm, preferably 7-50nm and more preferably 10-25nm.

[0076] In order to improve the light extraction efficiency of the organic electroluminescent device, a light extraction layer (i.e., CPL layer) can be added on the electrode (preferably the cathode) on the light emitting side of the device. According to the principles of optical absorption and refraction, the refractive index of the CPL cover layer material should be as high as possible, and the absorption coefficient should be as small as possible. Any material known in the art can be used as the CPL layer material, such as Alq 3 , CPL-1 (its specific structure will be shown below). The thickness of the CPL cover layer is generally 5-300 nm, preferably 20-100 nm and more preferably 40-80 nm.

[0077] The organic electroluminescent device may further include an encapsulation structure. The encapsulation structure may be a protective structure that prevents foreign substances such as moisture and oxygen from entering the organic layer of the organic electroluminescent device. The encapsulation structure may be, for example, a can, such as a glass can or a metal can; or a thin film covering the entire surface of the organic layer.

[0078] The preferred device structure of the organic electroluminescent device of the present invention adopts the top emitting form. Preferably, the anode of the organic electroluminescent device of the present invention adopts an electrode with high reflectivity, preferably ITO / Ag / ITO; the cathode adopts a transparent electrode, preferably a mixed electrode of Mg:Ag=1:9, thereby forming a microcavity resonance effect, and the device emits light from the Mg:Ag electrode side.

[0079] Method for preparing organic electroluminescent device

[0080] The present invention also relates to a method for preparing the above-mentioned organic electroluminescent device, which comprises laminating a first electrode, an organic functional material layer and a second electrode on a substrate in sequence. The organic functional material layer is formed by laminating a hole transport region, a light-emitting layer and an electron transport region in sequence from bottom to top on the first electrode, the hole transport region is formed by laminating a hole injection layer, a hole transport layer and an electron blocking layer in sequence from bottom to top on the first electrode, and the electron transport region is formed by laminating a hole blocking layer, an electron transport layer and an electron injection layer in sequence from bottom to top on the light-emitting layer. In addition, a CPL layer can also be laminated on the second electrode to improve the light extraction efficiency of the organic electroluminescent device.

[0081] For lamination, vacuum deposition, vacuum evaporation, spin coating, casting, LB method, inkjet printing, laser printing or LITI methods may be used, but are not limited thereto. Vacuum evaporation means heating and coating a material onto a substrate in a vacuum environment.

[0082] In the present invention, the various layers are preferably formed by vacuum evaporation, wherein the layers can be formed at a temperature of about 100-500° C. and at a temperature of about 10 -8 -10 -2 Torr vacuum and approx. Preferably, the temperature is 200-400°C, more preferably 250-300°C. The vacuum degree is preferably 10 -6 -10 -2 Torr, more preferably 10 -5 -10 -3 The rate is about More preferably, about

[0083] In addition, it should be noted that the materials used to form each layer described in the present invention can be formed into a film alone and used as a single layer, or can be mixed with other materials to form a film and used as a single layer. It can also be a stacked structure between layers formed into films alone, a stacked structure between layers formed into films after mixing, or a stacked structure of layers formed into films alone and layers formed into films after mixing.

[0084] Display device

[0085] The present invention also relates to a display device including the above-mentioned organic electroluminescent device, in particular a flat panel display device. In a preferred embodiment, the display device may include one or more of the above-mentioned organic electroluminescent devices, and in the case of including a plurality of devices, the devices are stacked and combined laterally or longitudinally. The display device may also include at least one thin film transistor. The thin film transistor may include a gate electrode, a source electrode and a drain electrode, a gate insulating layer and an active layer, wherein one of the source electrode and the drain electrode may be electrically connected to the first electrode of the organic electroluminescent device. The active layer may include crystalline silicon, amorphous silicon, an organic semiconductor or an oxide semiconductor, but is not limited thereto.

[0086] Exemplary embodiments have been disclosed herein, and although specific terms are used therein, these terms are used and interpreted only as general and descriptive meanings, and not for limiting purposes. In some cases, as will be apparent to those of ordinary skill in the art with the filing of this application, unless specifically indicated, the features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with the features, characteristics, and / or elements described in conjunction with other embodiments. Accordingly, it will be understood by those skilled in the art that various changes may be made in form and detail without departing from the spirit and scope of the invention.

[0087] I. Preparation of the First Electron Transport Compound

[0088] Example 1: Compound I-1

[0089]

[0090] (1) In a 500 ml round-bottom flask under nitrogen atmosphere, the raw material E1 (2.671 g, 10 mmol) and the raw material F1 (2.820 g, 10 mmol) were completely dissolved in 200 ml of xylene, and sodium tert-butoxide (0.96 g, 10 mmol) was added. Pd(t-Bu 3 P) 2 (0.10 g, 0.20 mmol), and then heated and stirred for 5 hours. The temperature was lowered to room temperature, and after filtering and removing the alkali, the xylene was concentrated under reduced pressure and recrystallized from 220 ml of ethyl acetate to obtain intermediate G1 (2.35 g, yield 50%);

[0091] (2) In a 500 ml round-bottom flask under nitrogen atmosphere, the intermediate G1 (4.69 g, 10 mmol) and the raw material H1 (2.67 g, 10 mmol) were completely dissolved in 300 ml of tetrahydrofuran (THF), and a 2 M potassium carbonate solution (KCO3) was added. 2 CO 3 )150ml, add Pd(PPh 3 )4 (0.34 g, 0.30 mmol), heated and stirred for 6 hours, then cooled to room temperature, the water layer was removed, dried over anhydrous magnesium sulfate and concentrated under reduced pressure, and recrystallized using 280 ml of ethyl acetate to obtain compound I-1 (4.54 g, yield 79%).

[0092] Example 2: Compound I-2

[0093]

[0094] Example 3: Compound I-3

[0095]

[0096] Example 4: Compound I-4

[0097]

[0098] Example 5: Compound I-5

[0099]

[0100] Example 6: Compound I-6

[0101]

[0102] Example 7: Compound I-7

[0103]

[0104] Example 8: Compound I-16

[0105]

[0106] Example 9: Compound I-20

[0107]

[0108] Example 10: Compound I-28

[0109]

[0110] Example 11: Compound I-34

[0111]

[0112] Example 12: Compound I-49

[0113]

[0114] Example 13: Compound I-50

[0115]

[0116] (1) In a flask, raw material A1 (13.4 g, 50 mmol), raw material B1 (16.9 g, 60 mmol), CuI (4.8 g, 25 mmol) and K 3 PO 4 (31.8 g, 150 mmol) was dissolved in 500 ml of toluene, and the mixture was refluxed at 120° C. for 5 hours. After the reaction was completed, the organic layer was extracted with ethyl acetate, the residual moisture was removed using magnesium sulfate and dried, and separated by column chromatography to obtain intermediate C1 (14.5 g, yield 69%);

[0117] (2) In a flask, intermediate C1 (12.6 g, 30 mmol), 4,4,4',4',5,5,5',5'-octamethyl-2,2'-bi(1,3,2-dioxaborolane) (11.4 g, 45 mmol), KOAC (8.8 g, 90 mmol) and Pd(PPh 3 ) 2 Cl 2 (2.1 g, 0.003 mol) was dissolved in 300 mL of dioxane, and the mixture was refluxed. After the reaction was completed, the organic layer was extracted with ethyl acetate, the residual moisture was removed using magnesium sulfate and dried, and separated by column chromatography to obtain intermediate D1 (8.2 g, yield: 58%);

[0118] (3) In a flask, intermediate D1 (9.4 g, 20 mmol), raw material M1 (8.6 g, 24 mmol), Pd(PPh 3 ) 4 (1.3 g, 1.0 mmol) and K 2 CO 3 (7.4 g, 55 mmol) was dissolved in toluene, ethanol and H 2 After adding 2-Hydroxy-1-(4-oxo-2-yl)-4-nitropropene to the mixture of 4-(4-oxo-1-yl)-4-nitropropene, the mixture was refluxed at 120° C. for 24 hours. After the reaction was completed, the organic layer was extracted with ethyl acetate, dried and separated by column chromatography to obtain compound I-50 (5.9 g, yield: 45%).

[0119] Example 14: Synthesis of Compound I-52

[0120]

[0121] Example 15: Synthesis of Compound I-57

[0122]

[0123] Example 16: Synthesis of Compound I-66

[0124]

[0125] Example 17: Synthesis of Compound I-72

[0126] Example 18: Synthesis of Compound I-87

[0127]

[0128] Example 19: Synthesis of Compound I-89

[0129] II. Preparation of the Second Electron Transport Compound

[0130] Example 1: Compound II-1

[0131]

[0132] 4.64 g of raw material J1 was dissolved in 50 ml of acetonitrile, and 2.5 M n-BuLi (15.5 mL, 36.36 mmol) was gradually added dropwise to the solution under nitrogen atmosphere at room temperature. After adding n-BuLi, the mixture was stirred for 1 h. The yellow solid was filtered out, washed with a small amount of ice water and acetonitrile, and finally air-dried. 4.7 g of solid was obtained, with a yield of 93%.

[0133] Example 2: Compound II-3

[0134]

[0135] (1) Raw material J2 3.2g, raw material K2 2.46g and Cs 2 CO 3 3.0g was mixed, 60ml of toluene, 12ml of ethanol and 12ml of water were added, and Pd(OAc) was added 2 55 mg and 250 mg of Xphos were heated and stirred for 4 hours. After the reaction was completed, the temperature was lowered to room temperature and then filtered. The filtrate was poured into water, extracted with chloroform, and MgSO 4 The organic layer was dried, concentrated under reduced pressure, and subjected to column chromatography to obtain 2.74 g (yield 69%) of white solid intermediate L2;

[0136] (2) 2.74 g of intermediate L2 was dissolved in 50 ml of acetonitrile, and 2.5 M n-BuLi (15.5 mL, 36.36 mmol) was gradually added dropwise to the solution under nitrogen atmosphere at room temperature. After adding n-BuLi, the mixture was stirred for 1 h. The yellow solid was filtered off, washed with a small amount of ice water and acetonitrile, and finally air-dried. 2.53 g of solid was obtained, with a yield of 90%.

[0137] The preparation methods of the remaining second electron transport compounds are the same as that of compound II-3, and the raw materials and reaction equations involved are as follows:

[0138] Example 3: Compound II-4

[0139]

[0140] Example 4: Compound II-5

[0141]

[0142] Example 5: Compound II-6

[0143]

[0144] Example 6: Compound II-28

[0145]

[0146] Example 7: Compound II-30

[0147]

[0148] Example 8: Compound II-39

[0149]

[0150] Example 9: Compound II-40

[0151]

[0152] Example 10: Compound II-44

[0153]

[0154] Example 11: Compound II-45

[0155]

[0156] Example 12: Compound II-47

[0157]

[0158] Example 13: Compound II-48

[0159]

[0160] Table 1

[0161]

[0162]

[0163]

[0164]

[0165]

[0166]

[0167] The glass transition temperature (Tg) of the first electron transport compound and the second electron transport compound synthesized in the embodiment was measured by DSC. The data in Table 2 show that they are stable in the thin film state. In order to further illustrate their electron injection and transport capabilities, their HOMO energy level, LUMO energy level and electron mobility were tested. The data in Table 2 show that the first electron transport compound and the second electron transport compound have suitable LUMO energy levels, indicating that they have good electron injection capabilities; compared with the electron mobility of traditional electron transport materials of 1.0 to 2.0*10E-4cm 2 / Vs, the compounds of the present invention have faster electron mobility, indicating that they have good electron transport properties.

[0168] The structural formulas of the comparative compounds ET-1 and ET-2 used are as follows:

[0169]

[0170] Table 2

[0171]

[0172]

[0173] The LUMO energy level of the material is derived from the absolute value of the difference between the HOMO energy level and Eg. The compound was evaporated on ITO glass with a film thickness of 60nm, and then its HOMO energy level was tested by IPS-3 (Riken Keiki) equipment. The compound was evaporated on quartz glass with a film thickness of 60nm, and the ultraviolet absorption of the material was tested by an ultraviolet spectrophotometer (Beijing Puxi General Company, Model: TU-1901), and Eg was obtained by testing. The electron mobility of the material was tested by the single charge device method, and the compound was made into a single electron device, and the electron mobility was obtained by testing the IVL data of the device.

[0174] As can be seen from Table 2, the Tg and electron mobility of the first electron transport compound and the second transport compound according to the present invention are significantly higher than those of the comparative compound. Therefore, the first and second electron transport compounds of the present invention have properties of more stable and better electron injection ability than the prior art compounds. In addition, the first electron transport compound and the second transport compound according to the present invention are comparable to the comparative compound in terms of T1 and HOMO. However, in terms of LUMO, the first electron transport compound and the second electron transport compound of the present invention have unexpected properties. Specifically, the LUMO energy level (absolute value basis) of the first electron transport compound according to the present invention is substantially greater than the LUMO energy level (absolute value basis) of the comparative compound, which reduces the LUMO energy level barrier of the electron injection layer and the electron transport layer, and is conducive to the transmission of electrons from the electron injection layer to the electron transport layer. According to the present invention, the absolute value of the difference between the LUMO energy levels of the first electron transport compound and the second electron transport compound is between 0.2-0.9, preferably between 0.4-0.8. The appropriate LUMO energy level difference between the first electron transport compound and the second electron transport compound is conducive to the transmission of electrons. Since the first electron transport compound and the second electron transport compound of the present invention have the above excellent and unexpected properties, they are particularly suitable for preparing organic electroluminescent devices.

[0175] IV. Device Preparation Examples

[0176] Device Example 1

[0177] Substrate layer 1 / anode layer 2 (ITO (15nm) / Ag (150nm) / ITO (15nm)) / hole injection layer 3 (HT-1:P-1=97:3 mass ratio, thickness 10nm) / hole transport layer 4 (HT-1, thickness 130nm) / electron blocking layer 5 (EB-1, thickness 10nm) / light-emitting layer 6 (EMH-1:EMD-1=97:3 mass ratio, thickness 20nm) / hole blocking layer 7 (HB-1, thickness 5nm) / electron transport layer 8 (compound I-1:compound II-1 mass ratio 1:1, thickness 30nm) / electron injection layer 9 (Yb, thickness 1nm) / cathode layer 10 (Mg:Ag=1:9 mass ratio, thickness 15nm) / CPL layer 11 (CPL-1, thickness 70nm).

[0178] The specific preparation process is as follows:

[0179] like Figure 1 As shown, the substrate layer 1 is a glass substrate, and the ITO (15nm) / Ag (150nm) / ITO (15nm) anode layer 2 is washed, that is, alkaline washing, pure water washing, drying, and then ultraviolet-ozone washing are performed in sequence to remove organic residues on the surface of the anode layer. On the anode layer 2 after the above washing, a vacuum evaporation device (200*200mm evaporation equipment, purchased from Choshu Industry Co., Ltd., Japan) is used to evaporate HT-1 and P-1 with a film thickness of 10nm as the hole injection layer 3, and the mass ratio of HT-1 to P-1 is 97:3. Then, HT-1 with a thickness of 130nm is evaporated as the hole transport layer 4. Then, EB-1 with a thickness of 10nm is evaporated as the electron blocking layer 5. After the above-mentioned electron blocking material is deposited, the light-emitting layer 6 of the OLED light-emitting device is prepared, which includes EMH-1 as the main material and EMD-1 as the doping material, the mass ratio of EMH-1 and EMD-1 is 97:3, and the thickness of the light-emitting layer is 20nm. After the above-mentioned light-emitting layer 6, HB-1 is vacuum-deposited with a film thickness of 5nm, and this layer is the hole blocking layer 7; after the above-mentioned hole blocking layer 7, compound I-1 and compound II-1 are vacuum-deposited with a mass ratio of compound I-1 and compound II-1 of 1:1, and the film thickness is 30nm, and this layer is the electron transport layer 8. On the electron transport layer 8, a Yb layer with a film thickness of 1nm is prepared by a vacuum evaporation device, and this layer is the electron injection layer 9. On the electron injection layer 9, a Mg:Ag electrode layer with a film thickness of 15nm is prepared by a vacuum evaporation device, and the mass ratio of Mg and Ag is 1:9, and this layer is used as the cathode layer 10. On the cathode layer 10 , CPL-1 was vacuum-deposited to form a CPL layer 11 with a thickness of 70 nm.

[0180] Device Example 2 to Device Example 20

[0181] An organic electroluminescent device was prepared in the same manner as in Device Example 1, except that the parameters in Table 3 were used, wherein when the ratio of the first electron transport compound to the second electron transport compound was 5:5, the evaporation rates were controlled to be and When the ratio of the two is 6:4, the evaporation rates are controlled to be and When the ratio of the two is 4:6, the evaporation rates are controlled to be and When the ratio of the first electron transport compound to the second electron transport compound is 8:2, the evaporation rates are controlled to be and When the ratio of the two is 1:9, the evaporation rates are controlled as follows: and

[0182] Device Comparative Example 1 to Device Comparative Example 2

[0183] An organic electroluminescent device was prepared in the same manner as in Device Example 1, except that compounds ET-1 and ET-2 were used to replace the first electron transport compound in Example 1, as shown in Table 3, wherein when the ratio of the first electron transport compound to the second electron transport compound was 5:5, the evaporation rates were controlled to be respectively and When the ratio of the two is 6:4, the evaporation rates are controlled to be and When the ratio of the two is 4:6, the evaporation rates are controlled to be and

[0184] Device Example 21

[0185] Substrate layer 1 / anode layer 2 (ITO (15nm) / Ag (150nm) / ITO (15nm)) / hole injection layer 3 (HT-1:P-1=97:3 mass ratio, thickness 10nm) / hole transport layer 4 (HT-1, thickness 130nm) / electron blocking layer 5 (EB-1, thickness 10nm) / light-emitting layer 6 (EMH-1:EMD-1=97:3 mass ratio, thickness 20nm) / electron transport layer 7 (compound I-63:compound II-1 mass ratio 1:1, thickness 35nm) / electron injection layer 8 (Yb, thickness 1nm) / cathode layer 9 (Mg:Ag=1:9 mass ratio, thickness 15nm) / CPL layer 10 (CPL-1, thickness 70nm).

[0186] like Figure 2As shown, the substrate layer 1 is a glass substrate, and the ITO (15nm) / Ag (150nm) / ITO (15nm) anode layer 2 is washed, that is, alkaline washing, pure water washing, drying, and then ultraviolet-ozone washing are performed in sequence to remove organic residues on the surface of the anode layer. On the anode layer 2 after the above washing, a vacuum evaporation device is used to evaporate HT-1 and P-1 with a film thickness of 10nm as a hole injection layer 3, and the mass ratio of HT-1 to P-1 is 97:3. Then, HT-1 with a thickness of 130nm is evaporated as a hole transport layer 4. Then, EB-1 with a thickness of 10nm is evaporated as an electron blocking layer 5. After the above electron blocking material is evaporated, the light-emitting layer 6 of the OLED light-emitting device is manufactured, and its structure includes EMH-1 used as the main material of the OLED light-emitting layer 6, EMD-1 as the doping material, the mass ratio of EMH-1 to EMD-1 is 97:3, and the thickness of the light-emitting layer is 20nm. After the above-mentioned light-emitting layer 6, vacuum evaporation of compound I-63 and compound II-1 was continued, the mass ratio of compound I-63 and compound II-1 was 1:1, the film thickness was 35nm, and this layer was the electron transport layer 7. On the electron transport layer 7, a Yb layer with a film thickness of 1nm was made by vacuum evaporation equipment, and this layer was the electron injection layer 8. On the electron injection layer 8, a Mg:Ag electrode layer with a film thickness of 15nm was made by vacuum evaporation equipment, and the mass ratio of Mg and Ag was 1:9, and this layer was used as the cathode layer 9. On the cathode layer 9, 70nm of CPL-1 was vacuum evaporated as the CPL layer 10.

[0187] Device Example 22 to Device Example 40

[0188] An organic electroluminescent device was prepared in the same manner as in Device Example 21, except that the parameters in Table 4 were used, wherein when the ratio of the first electron transport compound to the second electron transport compound was 5:5, the evaporation rates were controlled to be and When the ratio of the two is 6:4, the evaporation rates are controlled as follows: and When the ratio of the two is 4:6, the evaporation rates are controlled to be and

[0189] Device Comparative Example 3 to Device Comparative Example 4

[0190] An organic electroluminescent device was prepared in the same manner as in device Example 21, except that compounds ET-1 and ET-2 were used to replace the first electron transport compound in Example 21, as shown in Table 4, wherein when the ratio of the first electron transport compound to the second electron transport compound was 5:5, the evaporation rates were controlled to be respectively and When the ratio of the two is 6:4, the evaporation rates are controlled to be and When the ratio of the two is 4:6, the evaporation rates are controlled to be and

[0191] The molecular structure formula of the relevant materials is shown below:

[0192]

[0193]

[0194] The structural formulas of ET-1 and ET-2 are shown above.

[0195] Table 3. Organic electroluminescent devices prepared in device examples 1-20 and device comparative examples 1-2

[0196]

[0197] Table 4 Device Preparation Organic electroluminescent devices prepared in device examples 21-40 and device comparative examples 3-4

[0198]

[0199] V. Device Testing Examples

[0200] The devices prepared above were tested for driving voltage, current efficiency, CIEx, CIEy and LT95.

[0201] Table 5

[0202]

[0203]

[0204] Note: The driving voltage and current efficiency are both at 10mA / cm 2 The test data below; driving voltage, current efficiency, CIEx, CIEy are all tested by Foster IVL test system (Suzhou Foster Scientific Instrument Co., Ltd.); LT95 refers to the time taken for the device brightness to decay to 95% of the initial brightness when the device current density is 20mA / cm2, and the unit is hr; the life test system is the EAS-62C OLED device life tester of Japan System Technology Co., Ltd.

[0205] It can be seen from Table 5 that using the first electron transport compound and the second electron transport compound of the present invention as an electron transport layer in an organic electroluminescent device significantly reduces the driving voltage of the prepared organic electroluminescent device, significantly improves the current efficiency, and greatly prolongs the device life LT95.

Claims

1. An organic electroluminescent device, comprising: A first electrode, a second electrode facing the first electrode, a light-emitting layer between the first electrode and the second electrode, and a cover layer on the electrode on a side where light is emitted; If the first electrode is an anode, the second electrode is a cathode; if the first electrode is a cathode, the second electrode is an anode; wherein a hole transport region is provided between the anode and the light-emitting layer, and an electron transport region is provided between the cathode and the light-emitting layer, wherein the electron transport region comprises an electron transport layer, wherein the electron transport layer comprises a first electron transport compound and a second electron transport compound, and the structure of the first electron transport compound is shown in general formula (1): In the general formula (1), Ar1 and Ar2 are independently any one of substituted or unsubstituted phenyl, substituted or unsubstituted biphenyl, substituted or unsubstituted pyridyl, substituted or unsubstituted naphthyl, and substituted or unsubstituted dibenzofuranyl; L is any one of substituted or unsubstituted phenylene, substituted or unsubstituted biphenylene, and substituted or unsubstituted pyridylene; Ring A and Ring B are each independently naphthyl; The second electron transport compound is a metal Li complex, and its structure is shown in any one of the general formulas (2), (3), (4) and (5): In the general formula (2), the general formula (3), the general formula (4) and the general formula (5), R1 to R 11 each independently represents one of hydrogen, deuterium, methyl, ethyl, isopropyl, tert-butyl, substituted or unsubstituted phenyl, substituted or unsubstituted biphenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted pyridyl, substituted or unsubstituted pyridazinyl, substituted or unsubstituted carbazolinyl, substituted or unsubstituted pyrimidinyl, substituted or unsubstituted pyrazinyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted carbazolyl, substituted or unsubstituted dibenzothiophenyl, substituted or unsubstituted quinolyl, substituted or unsubstituted isoquinolyl, substituted or unsubstituted naphthyridinyl, substituted or unsubstituted quinoxalinyl, substituted or unsubstituted cinnolinyl or substituted or unsubstituted quinazolinyl; Ar a ,Ar b Each independently represents any one of a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted pyridazinyl group, a substituted or unsubstituted quinolyl group, a substituted or unsubstituted dibenzofuranyl group, a substituted or unsubstituted carbazolyl group, and a substituted or unsubstituted carbazoline group; Each occurrence of Z is represented by N or CR d , where R d is represented by one of a hydrogen atom, a deuterium atom, a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted pyridazinyl group, a substituted or unsubstituted quinolyl group, a substituted or unsubstituted dibenzofuranyl group, a substituted or unsubstituted carbazolyl group, and a substituted or unsubstituted carbazoline group; The substituent for the substituent group may be selected from one or more of deuterium, cyano, fluorine atom and phenyl.

2. The organic electroluminescent device according to claim 1, characterized in that: The electron transport layer is located in direct contact with the light-emitting layer; Ar1 ​​and Ar2 are independently represented by substituted or unsubstituted phenyl, substituted or unsubstituted biphenyl, substituted or unsubstituted pyridyl, substituted or unsubstituted naphthyl, substituted or unsubstituted dibenzofuranyl; R1 to R 11 each independently represents hydrogen, deuterium, tert-butyl, substituted or unsubstituted phenyl, substituted or unsubstituted biphenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted pyridyl, substituted or unsubstituted carbazoline, substituted or unsubstituted pyrimidinyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted carbazolyl, substituted or unsubstituted quinolyl, substituted or unsubstituted isoquinolyl, substituted or unsubstituted naphthyridinyl, substituted or unsubstituted quinoxalinyl or substituted or unsubstituted quinazolinyl; Ar a ,Ar b R is independently a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted quinolyl group, a substituted or unsubstituted dibenzofuranyl group, a substituted or unsubstituted carbazolyl group, or a substituted or unsubstituted carbazoline group; d represented by a hydrogen atom, a deuterium atom, a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted quinolyl group, a substituted or unsubstituted dibenzofuranyl group, a substituted or unsubstituted carbazolyl group, or a substituted or unsubstituted carbazoline group; The substituent for the substituent group may be selected from one or more of deuterium, cyano and fluorine atoms.

3. The organic electroluminescent device according to claim 1, characterized in that: An additional hole blocking layer is provided between the electron transport layer and the light emitting layer.

4. The organic electroluminescent device according to claim 1, characterized in that: The structure of the first electron transport compound is any one of the following structures:

5. The organic electroluminescent device according to claim 1, characterized in that: The structure of the second electron transport compound is any one of the following structures:

6. The organic electroluminescent device according to any one of claims 1 to 5, characterized in that: The weight ratio of the first electron transport compound to the second electron transport compound is 1:10 to 10:

1.

7. The organic electroluminescent device according to any one of claims 1 to 5, characterized in that: The weight ratio of the first electron transport compound to the second electron transport compound is 1:9 to 9:

1.

8. The organic electroluminescent device according to any one of claims 1 to 5, characterized in that: A weight ratio of the first electron transport compound to the second electron transport compound is 2:8 to 8:

2.

9. The organic electroluminescent device according to any one of claims 1 to 5, characterized in that: A weight ratio of the first electron transport compound to the second electron transport compound is 3:7 to 7:

3.

10. The organic electroluminescent device according to claim 1, characterized in that: The thickness of the electron transport layer is 10-80 nm.

11. The organic electroluminescent device according to claim 1, characterized in that: The thickness of the electron transport layer is 20-60 nm.

12. The organic electroluminescent device according to claim 1, characterized in that: The thickness of the electron transport layer is 25-45 nm.

13. A method for preparing the organic electroluminescent device according to any one of claims 1 to 12, characterized in that: The method comprises laminating a first electrode, an organic functional material layer and a second electrode on a substrate from bottom to top, wherein the organic functional material layer consists of a hole transport region, a light emitting layer and an electron transport region, and the lamination is performed by vacuum evaporation at a temperature of 100-500° C. for 10 -8 -10 -2 Torr vacuum and / second rate.

14. A display device, characterized in that: The display device comprises the organic electroluminescent device according to any one of claims 1 to 12.

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