An organic electroluminescent device, a preparation method thereof, and a panel

Abstract

The present invention provides an organic electroluminescent device, a preparation method thereof, and a panel. The organic electroluminescent device includes an electron transport layer; the electron transport layer includes a first electron transport material and a second electron transport material; the first electron transport material has a structure shown in Formula I or Formula II; the second electron transport material has a structure shown in Formula IV. ETL1 and ETL2 form a Premix ETL material. By defining the structures of ETL1 and ETL2, the ETL1 and ETL2 included in the Premix ETL material have mutually matching electron injection performance and electron transport performance. The combination of an ETL molecule with excellent electron injection performance and an ETL molecule with excellent electron transport performance is matched to form an electron transport layer, which can exert the maximum efficacy, can well replace ETL doped with LiQ, can realize better electron injection and transport in the device, and thus obtain more excellent device performance.

Description

Technical Field

[0001] The present invention relates to the technical field of organic electroluminescent devices, and particularly to an organic electroluminescent device, a preparation method thereof, and a panel. Background Art

[0002] In recent years, organic electroluminescent displays (OLEDs) have gradually received more attention as a new type of flat panel display. Due to their characteristics such as active light emission, high luminance, high resolution, wide viewing angle, fast response speed, low power consumption, and flexibility, they have become a popular mainstream display product in the market.

[0003] With the continuous advancement of OLED technology, OLED devices have gradually developed into multi-layer thin film devices with multiple functional layers. People have paid more attention to the research on high-efficiency organic materials and device performance that affect OLEDs. An organic electroluminescent device with good efficiency and long lifespan is usually the result of an optimized combination of various organic materials, which provides great opportunities and challenges for the design and development of functional materials and device structures with various structures. The electron transport layer (ETL), as the main carrier transport channel, has a decisive impact on key device performance such as voltage, efficiency, and lifespan. Currently, the electron transport layer is mainly composed of co-evaporation of an organic material and lithium 8-hydroxyquinolate (LiQ) as the electron transport layer.

[0004] LiQ has extremely strong injection characteristics and is used as the electron transport layer by doping with ET, which can effectively improve the injection characteristics of the device, and then can reduce the operating voltage of the device and improve the efficiency. However, since LiQ belongs to an organometallic complex, the material stability is relatively weaker than that of organic materials. During the operation of the device, LiQ is prone to cracking, and Li atoms are prone to diffusion, passing through the HBL layer into the light-emitting layer. In the EML layer, Li will act as a quenching center, causing singlet excitons and triplet excitons to be quenched and deactivated, thereby affecting the recombination luminescence of excitons. Furthermore, it affects the lifespan and efficiency of the device. In addition, the mobility of LiQ is poor, and doping LiQ is not conducive to electron transport. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide an organic electroluminescent device, a preparation method thereof, and a panel, and the provided organic electroluminescent device avoids the use of LiQ and has high efficiency and lifespan.

[0006] The present invention provides an organic electroluminescent device, including an electron transport layer;

[0007] The electron transport layer includes a first electron transport material and a second electron transport material;

[0008] The first electron transport material has a structure represented by Formula I or Formula II:

[0009]

[0010] In Formula I, X is CR5R6, O, S, NR7 or a single bond;

[0011] Ar1, Ar2, Ar3, and Ar4 are independently selected from H, substituted or unsubstituted aryl or heteroaryl having 5 to 30 ring atoms, and at least one of Ar1, Ar2, Ar3, and Ar4 is selected from the structure shown in Formula III:

[0012]

[0013] R3 and R4 are independently selected from substituted or unsubstituted aryl or heteroaryl;

[0014] X4, X5, and X6 are independently selected from CH or N, and at least one is N;

[0015] R5, R6, and R7 are independently selected from substituted or unsubstituted C1-C10 alkyl;

[0016] In Formula II, X1, X2, and X3 are independently selected from CH or N, and at least one is N;

[0017] R1 and R2 are independently selected from substituted or unsubstituted aryl or heteroaryl;

[0018] L1 is selected from substituted or unsubstituted arylene or heteroarylene;

[0019] A is selected from cyano, aryl, heteroaryl, cyano-substituted aryl, or cyano-substituted heteroaryl;

[0020] The second electron transport material has the structure shown in Formula IV:

[0021]

[0022] Wherein, L is substituted or unsubstituted phenylene, biphenylene, naphthylene;

[0023] Ar5 or Ar6 is substituted or unsubstituted aryl, heteroaryl, C1-C10 alkyl;

[0024] Y is O or S;

[0025] B is substituted or unsubstituted C6-C60 aryl, C2-C60 heteroaryl;

[0026] And Ar5 or Ar6 can form a ring with L and B.

[0027] The present invention provides a display panel, including the above-mentioned organic electroluminescent device.

[0028] The electron transport layer of the present invention comprises a first electron transport material ETL1 and a second electron transport material ETL2. ETL1 and ETL2 form a Premix ETL material. By defining the structures of ETL1 and ETL2, the ETL1 and ETL2 comprised in the Premix ETL material have mutually matched electron injection performance and electron transport performance. The combination of an ETL molecule with excellent electron injection performance and an ETL molecule with excellent electron transport performance is matched to form an electron transport layer, which can exert the maximum efficacy, can well replace the ETL doped with LIQ, can realize better electron injection and transport in the device, and thus obtain more excellent device performance.

[0029] On the other hand, the two evaporation sources used for doping LiQ in the ETL in the existing solution can be replaced with one evaporation source for Premix ETL, thereby reducing the production cost; in addition, LiQ is prone to cracking, while both ETL1 and ETL2 comprised in the Premix ETL material of the present invention are pure organic compounds, and the thermal stability of the material is more excellent than that of LiQ, thus reducing the adverse effect on the device performance caused by the cracking of LiQ. Description of the Drawings

[0030] Figure 1 is a schematic structural diagram of an organic light-emitting device provided by the present invention;

[0031] Among them, 110 is a glass substrate, 120 is an anode, 130 is a hole injection layer, 140 is a hole transport layer A, 150 is a hole transport layer B, 160 is a light-emitting layer, 170 is an electron transport layer, and 180 is a cathode. Detailed Embodiments

[0032] The present invention provides an organic electroluminescent device, comprising an electron transport layer;

[0033] The electron transport layer comprises a first electron transport material and a second electron transport material;

[0034] The first electron transport material has a structure shown in Formula I or Formula II:

[0035]

[0036] In Formula I, X is CR5R6, O, S, NR7 or a single bond;

[0037] Ar1, Ar2, Ar3, Ar4 are independently selected from H, a substituted or unsubstituted aryl or heteroaryl having 5 to 30 ring atoms, and at least one of Ar1, Ar2, Ar3, Ar4 is selected from the structure shown in Formula III:

[0038]

[0039] R3 and R4 are independently selected from substituted or unsubstituted aryl or heteroaryl;

[0040] X4, X5, and X6 are independently selected from CH or N, and at least one is N;

[0041] R5, R6, and R7 are independently selected from substituted or unsubstituted C1-C10 alkyl;

[0042] In formula II, X1, X2, and X3 are independently selected from CH or N, and at least one is N;

[0043] R1 and R2 are independently selected from substituted or unsubstituted aryl or heteroaryl;

[0044] L1 is selected from substituted or unsubstituted arylene or heteroarylene;

[0045] A is selected from cyano, aryl, heteroaryl, cyano-substituted aryl, or cyano-substituted heteroaryl;

[0046] The second electron transport material has the structure shown in formula IV:

[0047]

[0048] Wherein, L is substituted or unsubstituted phenylene, biphenylene, naphthylene;

[0049] Ar5 or Ar6 is substituted or unsubstituted aryl, heteroaryl, C1-C10 alkyl;

[0050] Y is O or S;

[0051] B is substituted or unsubstituted C6-C60 aryl, C2-C60 heteroaryl;

[0052] And Ar5 or Ar6 can form a ring with L and B.

[0053] The heteroatoms of the above-mentioned heteroaryl include but are not limited to one or more of O, S, N, and Si.

[0054] Optionally, the dipole moment of the first electron transport material (ETL1) having the structure shown in formula I or formula II is 0-6D, and the dipole moment of the second electron transport material (ETL2) having the structure shown in formula IV is 4-15D.

[0055] The above-mentioned ETL1 with a dipole moment of 0-6D has good transport performance; the ETL2 with a dipole moment of 4-15D has good injection characteristics, similar to LIQ.

[0056] Optionally, the dipole moment of ETL1 includes but is not limited to 0.35D, 0.51D, 0.94D, 5.2D, 5.5D.

[0057] Optionally, the dipole moment of ETL2 is 4 - 6 D.

[0058] Optionally, the dipole moment of ETL2 includes, but is not limited to, 4.19 D, 4.43 D, 4.46 D, 5.04 D, 5.17 D.

[0059] Optionally, when the dipole moment of ETL1 is small, 0 - 1 D, the mass ratio of ETL1 and ETL2 is 50:50 - 30:70.

[0060] Optionally, the above mass ratio includes, but is not limited to, 3:7, 4:6, or 5:5.

[0061] When the dipole moment of ETL1 is large, 2 - 6 D, the mass ratio of ETL1 and ETL2 is 80:20 - 60:40.

[0062] Optionally, the above mass ratio includes, but is not limited to, 8:2, 7:3, 6:4.

[0063] When the dipole moment of ETL1 is small, ETL1 has little contribution to the injectivity. At this time, ETL1 only plays a role in transportation. At this time, a relatively large proportion of ETL2 needs to be doped to improve the injection characteristics of the material. When the dipole moment of ETL1 is large, ETL1 has a certain contribution to the injectivity. At this time, in addition to playing a role in transportation, ETL1 also contributes to the injection characteristics. A small proportion of ETL2 needs to be doped to assist in improving the injection characteristics of the material. Such a ratio can ensure that the formed hybrid ETL layer can not only take into account the injection characteristics but also have a fast transportation characteristic, making it have the characteristics of traditional ETL doped with LIQ and can also solve the adverse effects brought by the introduction of LIQ.

[0064] The test results show that the device prepared with the above ratio of ETL1 and ETL2 has a higher lifespan and efficiency, and a lower voltage.

[0065] Optionally, the absolute value of the difference between the lowest unoccupied molecular orbital energy level (LUMO energy level) of ETL1 and the lowest unoccupied molecular orbital energy level (LUMO energy level) of ETL2 ≤ 0.3 eV.

[0066] It can be expressed as: |LUMO(ETL1) - LUMO(ETL2)| ≤ 0.3 eV.

[0067] Optionally, the triplet energy level (T1) of ETL1 ≥ 2.35 eV; the triplet energy level (T1) of ETL2 ≥ 2.35 eV.

[0068] It can be expressed as: T1(ETL1) ≥ 2.35 eV; T1(ETL2) ≥ 2.35 eV.

[0069] Optionally, the triplet energy level (T1) of the emitting layer (EML) of the organic electroluminescent device is less than or equal to the triplet energy level (T1) of the electron blocking layer (EBL); the triplet energy level (T1) of the emitting layer (EML) of the organic electroluminescent device is less than or equal to the triplet energy level (T1) of the electron transport layer (Premix ETL composed of ETL1 and ETL2).

[0070] It can be expressed as: T1(EML) ≤ T1(EBL); T1(EML) ≤ T1(Premix ETL).

[0071] By defining the structure, the first electron transport material and the second electron transport material form a Premix ETL material, which has mutually matching electron injection performance and electron transport performance, is beneficial to reducing the energy level barrier caused by too large an energy level difference in the mixed electron transport layer, resulting in blocked electron transport and further causing a decrease in the material mobility. At the same time, the exciton can be confined in the emitting layer to prevent the energy from being fed back to the functional layer adjacent to the EML, thereby further improving the efficiency of the device.

[0072] In order to make the first electron transport material and the second electron transport material have a higher degree of matching and enable the device to obtain the best performance, the present invention optimizes the structures of the first electron transport material and the second electron transport material.

[0073] Optionally, in formula I, X is CR5R6, O, S, NR7 or a single bond;

[0074] Ar1, Ar2, Ar3, Ar4 are independently selected from H, substituted or unsubstituted monocyclic aryl, monocyclic heteroaryl, and at least one of Ar1, Ar2, Ar3, Ar4 is selected from the structure shown in formula III:

[0075]

[0076] R3, R4 are independently selected from substituted or unsubstituted monocyclic aryl, five- or six-membered monocyclic heteroaryl, a group formed by connecting or fusing 2 to 3 monocyclic aryl and / or five- or six-membered monocyclic heteroaryl through a single bond, and fluorenyl;

[0077] The heteroatom of the monocyclic heteroaryl is selected from one or more of N, O, S, and Si;

[0078] X4, X5, X6 are independently selected from CH or N, and at least one is N;

[0079] R5, R6, R7 are independently selected from substituted or unsubstituted C1-C6 alkyl.

[0080] Optionally, in formula I, X is CR5R6, O, S, NR7 or a single bond;

[0081] Ar1, Ar2, Ar3, and Ar4 are independently selected from H, substituted or unsubstituted phenyl, pyridyl, pyrrolyl, pyrimidinyl, pyrazinyl, and triazinyl, and at least one of Ar1, Ar2, Ar3, and Ar4 is selected from the structure shown in Formula III:

[0082]

[0083]

[0084] R3 and R4 are independently selected from substituted or unsubstituted phenyl, biphenyl, 4-pyridylphenyl, pyridyl, pyrrolyl, pyrimidinyl, pyrazinyl, triazinyl, naphthyl, anthryl, phenanthryl, quinolinyl, isoquinolinyl, quinoxalinyl, quinazolinyl, carbazolyl, dibenzofuranyl, dibenzothiophenyl, and fluorenyl;

[0085] X4, X5, and X6 are all N;

[0086] R5, R6, and R7 are independently selected from substituted or unsubstituted methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and tert-butyl.

[0087] Optionally, the substituents of Ar1, Ar2, Ar3, Ar4, R3, R4, R5, R6, and R7 are independently selected from deuterium, halogen, and C1-C6 alkyl.

[0088] Optionally, the compound shown in Formula I has any of the following structures:

[0089]

[0090] Optionally, in Formula II, X1, X2, and X3 are independently selected from CH or N, and at least one is N;

[0091] R1 and R2 are independently selected from substituted or unsubstituted monocyclic aryl, five- or six-membered monocyclic heteroaryl, and groups formed by linking or fusing 2-3 monocyclic aryl and / or five- or six-membered monocyclic heteroaryl through single bonds;

[0092] The heteroatoms of the monocyclic heteroaryl are selected from one or more of N, O, S, and Si;

[0093] L1 is selected from substituted or unsubstituted monocyclic aryl, five- or six-membered monocyclic heteroaryl, groups formed by linking or fusing 2-3 monocyclic aryl and / or five- or six-membered monocyclic heteroaryl through single bonds, and fluorenyl;

[0094] The heteroatoms of the monocyclic heteroaryl are selected from one or more of N, O, S, and Si;

[0095] A is selected from cyano, phenyl, monocyclic heteroaryl, cyano-substituted phenyl, and cyano-substituted monocyclic heteroaryl.

[0096] Optionally, in Formula II, X1, X2, and X3 are all N;

[0097] R1 and R2 are independently selected from substituted or unsubstituted phenyl and pyridyl;

[0098] L1 is selected from substituted or unsubstituted phenylene, pyridylene, biphenylene, and fluorenylene;

[0099] A is selected from cyano, phenyl, pyridyl, cyano-substituted phenyl, and cyano-substituted pyridyl.

[0100] Optionally, the compound represented by Formula II has any of the following structures:

[0101]

[0102] Optionally, in the structure of Formula IV, Ar5 or Ar6 is a substituted or unsubstituted monocyclic aryl group, a five- or six-membered monocyclic heteroaryl group, a group formed by linking or fusing 2 to 3 monocyclic aryl groups and / or five- or six-membered monocyclic heteroaryl groups through single bonds, or a C1-C6 alkyl group;

[0103] The heteroatom of the monocyclic heteroaryl group is selected from one or more of N, O, S, and Si;

[0104] B is a substituted or unsubstituted monocyclic aryl group, a five- or six-membered monocyclic heteroaryl group, or a group formed by linking or fusing 2 to 3 monocyclic aryl groups and / or five- or six-membered monocyclic heteroaryl groups through single bonds;

[0105] The heteroatom of the monocyclic heteroaryl group is selected from one or more of N, O, S, and Si.

[0106] Optionally, in the structure of Formula IV, Ar5 or Ar6 is a substituted or unsubstituted phenyl, naphthyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or tert-butyl;

[0107] B is a substituted or unsubstituted phenyl, naphthyl, anthracenyl, bianthracenyl, or phenanthryl.

[0108] Optionally, the compound represented by Formula IV has any of the following structures:

[0109]

[0110] The above-mentioned organic electroluminescent device provided by the present invention can be an organic light-emitting device well-known to those skilled in the art. Optionally, the organic light-emitting device includes a substrate, an ITO anode, a hole injection layer HIL (optionally with a thickness of 5 - 30 nm), a hole transport layer HTL (optionally with a thickness of 100 - 2000 nm), an electron blocking layer EBL (optionally with a thickness of 5 - 100 nm), a light-emitting layer EML (optionally with a thickness of 20 - 100 nm), a hole blocking layer HBL (optionally with a thickness of 5 - 100 nm), an electron transport layer ETL (optionally with a thickness of 20 - 100 nm), an electron injection layer EIL (optionally with a thickness of 1 - 10 nm), and a cathode.

[0111] Optionally, the structure of the organic electroluminescent device is as follows:

[0112] ITO / HIL(10nm) / HTL(100nm) / EBL(10nm) / Host:Dopant(1:1, 3wt%, 20nm) / HBL(5nm) / ETL:LIQ(1:1, 30nm) or ET-1:ET-2 (different ratios, 30nm) / cathode(100nm).

[0113] Optionally, the anode material of the organic electroluminescent device of the present invention can be selected from metals - copper, gold, silver, iron, chromium, nickel, manganese, palladium, platinum, etc. and their alloys; such as metal oxides - indium oxide, zinc oxide, indium tin oxide (ITO), indium zinc oxide (IZO), etc.; such as conductive polymers - polyaniline, polypyrrole, poly(3-methylthiophene), etc. In addition to the above hole injection - assisting materials and their combinations, it also includes known materials suitable for making anodes.

[0114] Optionally, the cathode material of the organic electroluminescent device of the present invention can be selected from metals - aluminum, magnesium, silver, indium, tin, titanium, etc. and their alloys; such as multi - layer metal materials - LiF / Al, LiO2 / Al, BaF2 / Al, etc. In addition to the above electron injection - assisting materials and their combinations, it also includes known materials suitable for making cathodes.

[0115] Optionally, in the organic electroluminescent device of the present invention, there is at least one light - emitting layer (EML) and an electron transport layer (ETL) in the organic thin - film layer, and it can also include other functional layers, including a hole injection layer (HIL), a hole transport layer (HTL), an electron blocking layer (EBL), a hole blocking layer (HBL), and an electron injection layer (EIL).

[0116] Optionally, the organic light - emitting device of the present invention is prepared according to the following method:

[0117] Form an anode on a transparent or opaque smooth substrate, form an organic thin layer on the anode, and form a cathode on the organic thin layer.

[0118] Optionally, known film-forming methods such as evaporation, sputtering, spin coating, dipping, ion plating, etc. can be used to form the organic thin layer.

[0119] In the present invention, ETL1 and ETL2 in the above-mentioned electron transport layer can be evaporated by co-evaporation or premixing. The premixing can be carried out by physical grinding, co-sublimation or solvent co-dissolution for pre-mixing.

[0120] Optionally, the evaporation temperatures of ETL1 and ETL2 differ by no more than 30 °C, which can prevent uneven evaporation of the material due to too low temperature or cracking of the material due to too high temperature.

[0121] In the present invention, the above-mentioned organic light-emitting device (OLED device) can be used in a display device, and the organic light-emitting display device can be a mobile phone display screen, a computer display screen, a TV display screen, a smart watch display screen, a smart car display panel, a VR or AR helmet display screen, a display screen of various smart devices, etc.

[0122] Based on this, the present invention provides a panel including the above-mentioned organic light-emitting device.

[0123] The present invention also provides a display device including the above-mentioned display panel.

[0124] Next, the technical solutions of the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0125] Example 1

[0126] Using the computational chemistry software "Spartan‘18", the dipole moment of the equilibrium geometry in the ground state at the B3LYP / 6-31g* calculation level is calculated using the DFT (Density Functional Theory) method. If there can be more than one conformation, the conformation with the lowest total energy is selected to determine the dipole moment. The dipole moment reflects the magnitude of the polarity of the material. The greater the polarity of the material, the better the injectivity, indicating that this material can improve injection and can replace LIQ. The results are shown in Table 1:

[0127] Table 1 Dipole Moments of Compounds

[0128] ETL1 Dipole moment (D) ETL2 Dipole moment (D) Compound 1 0.35 Compound 11 5.04 Compound 2 0.51 Compound 12 5.17 Compound 3 0.94 Compound 13 4.19 Compound 6 5.2 Compound 14 4.46 Compound 7 5.5 Compound 15 4.43

[0129] Device Example

[0130] Preparation process:

[0131] (1) Ultrasonically treat the glass plate with ITO in a cleaning agent, rinse it in deionized water, ultrasonically remove oil in an acetone - ethanol mixed solvent, and bake it in a clean environment until all moisture is completely removed;

[0132] (2) Place the above - mentioned glass substrate with an anode in a vacuum chamber, evacuate to 1*10 -5 Pa, and vacuum - evaporate a hole - injection material on the above - mentioned anode layer film to form a hole - injection layer;

[0133] (3) Evaporate a hole - transporting material on the hole - injection layer to form a hole - transporting layer;

[0134] (4) Vacuum - evaporate an electron - blocking layer of the device on the hole - transporting layer;

[0135] (5) Vacuum - evaporate a light - emitting layer of the device on the electron - blocking layer. The light - emitting layer includes a host material and a guest material. Using the method of co - evaporation from multiple sources, the weight ratio of the host and guest materials is 90:10;

[0136] (6) Vacuum - evaporate a hole - blocking layer of the device on the light - emitting layer;

[0137] (7) Vacuum - evaporate an electron - transporting layer of the device on the hole - blocking layer. The electron - transporting layer material in the present invention is Premix ETL. The two ETLs in this material have been mixed during material preparation and are placed in one evaporation crucible for evaporation;

[0138] (8) Vacuum - evaporate 0.5 nm thick LiF as an electron - injection layer on the electron - transporting layer (ETL).

[0139] (9) Evaporate an Al layer on the electron - injection layer as the cathode of the device.

[0140] The material structures of each functional layer of the OLED device are as follows:

[0141]

[0142] In the above - mentioned device, the ETL layer is shown in Table 2:

[0143] Table 2 Composition and ratio of the ETL layer in the device

[0144] Device Example ETL (Doping Ratio) Device Example 1 Compound 1: Compound 11 (3:7) Device Example 2 Compound 1: Compound 11 (4:6) Device Example 3 Compound 1: Compound 11 (5:5) Device Example 4 Compound 1: Compound 11 (6:4) Device Example 5 Compound 1: Compound 11 (7:3) Device Example 6 Compound 6: Compound 12 (9:1) Device Example 7 Compound 6: Compound 12 (8:2) Device Example 8 Compound 6: Compound 12 (7:3) Device Example 9 Compound 6: Compound 12 (6:4) Device Example 10 Compound 6: Compound 12 (3:7) Device Example 11 Compound 6: Compound 12 (2:8) Comparative Example 1 Compound 1: LiQ Comparative Example 2 Compound 6: LiQ

[0145] For the organic light - emitting diode manufactured by the above - mentioned method, the performance results of the device tested at a fixed current density are shown in Table 3.

[0146] Table 3 Device performance detection

[0147] Example Voltage Efficiency Lifetime CIEx CIEy Device Example 1 96.53％ 110.67％ 105.24％ 0.1341 0.1185 Device Example 2 97.22％ 103.41％ 103.18％ 0.1339 0.1168 Device Example 3 99.34％ 103.12％ 107.76％ 0.1337 0.1122 Device Example 4 101.55％ 101.98％ 99.01％ 0.1335 0.1232 Device Example 5 102.84％ 99.01％ 96.89％ 0.1341 0.1194 Comparative Example 1 100％ 100％ 100％ 0.1344 0.1172 Device Example 6 99.53％ 102.67％ 98.24％ 0.1314 0.1132 Device Example 7 96.22％ 104.41％ 103.18％ 0.1332 0.1297 Device Example 8 99.14％ 103.12％ 107.76％ 0.1344 0.1168 Device Example 9 99.89％ 103.52％ 104.98％ 0.1341 0.1161 Device Example 10 102.55％ 99.48％ 93.01％ 0.1329 0.1311 Device Example 11 102.84％ 96.01％ 90.89％ 0.1333 0.1285 Comparative Example 2 100％ 100％ 100％ 0.1335 0.1268

[0148] For the organic light-emitting device prepared according to the example of the present invention, it can be seen that in the device structure, the ETL uses a new generation of Premix ETL to replace the traditional ETL doped with LiQ. By optimizing the ratio of the two components in Premix ETL according to the change of the dipole moment of the two-component system, the performance of the device can be greatly improved. As can be seen from the device results in Table 3, when the compound 1:LiQ in the ETL layer is replaced with compound 1:compound 11, and the ratios of compound 1:compound 11 are 3:7, 4:6, and 5:5 respectively, compared with Comparative Example 1, the voltages of the devices are reduced by 3.47%, 2.78%, and 0.66% respectively, the efficiencies are increased by 10.67%, 3.41%, and 3.12% respectively, and the lifetimes are increased by 5.24%, 3.18%, and 7.76% respectively. The voltage, efficiency, and lifetime performance of the devices are all improved. When the compound 6:LiQ in the ETL layer is replaced with compound 6:compound 12, and the ratios of compound 6:compound 12 are 8:2, 7:3, and 6:4 respectively, compared with Comparative Example 2, the voltages of the devices are reduced by 3.78%, 0.86%, and 0.11% respectively, the efficiencies are increased by 4.41%, 3.12%, and 3.52% respectively, and the lifetimes are increased by 3.18%, 7.76%, and 4.98% respectively. The voltage, efficiency, and lifetime performance of the devices are also all improved.

[0149] However, when the ratios of compound 1:compound 11 are 6:4 and 7:3 respectively, the performance of the devices prepared with these ratios is not as good as that of the devices prepared with the above ratios. Compared with Comparative Example 1, the voltages of the devices are increased by about 1.55% and 2.84% respectively, the lifetimes are reduced by 0.99% and 3.11% respectively, and when the ratio is 7:3, the efficiency is reduced by 0.99%. When the ratios of compound 6:compound 12 are 3:7 and 2:8 respectively, the performance of the devices prepared with these ratios is also not as good as that of the devices prepared with the above ratios. Compared with Comparative Example 2, the voltages of the devices are increased by 2.55% and 2.84% respectively, the efficiencies are reduced by 0.52% and 3.99% respectively, and the lifetimes are reduced by 6.99% and 9.11% respectively.

[0150] The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. An organic electroluminescent device, characterized in that, comprising an electron transport layer; the electron transport layer comprises a first electron transport material and a second electron transport material; the first electron transport material has a structure represented by Formula I or Formula II: In Formula I, X is CR5R6, O, S, NR7 or a single bond; Ar1, Ar2, Ar3, Ar4 are independently selected from H, substituted or unsubstituted aryl or heteroaryl having 5 to 30 ring atoms, and at least one of Ar1, Ar2, Ar3, Ar4 is selected from the structure represented by Formula III: R3 and R4 are independently selected from substituted or unsubstituted aryl or heteroaryl; X4, X5, X6 are independently selected from CH or N, and at least one is N; R5, R6, R7 are independently selected from substituted or unsubstituted C1-C10 alkyl; In Formula II, X1, X2, X3 are independently selected from CH or N, and at least one is N; R1, R2 are independently selected from substituted or unsubstituted aryl or heteroaryl; L1 is selected from substituted or unsubstituted arylene or heteroarylene; A is selected from cyano, aryl, heteroaryl, cyano-substituted aryl or cyano-substituted heteroaryl; the second electron transport material has a structure represented by Formula IV: wherein, L is substituted or unsubstituted phenylene, biphenylene, naphthylene; Ar5 or Ar6 is substituted or unsubstituted aryl, heteroaryl, C1-C10 alkyl; Y is O or S; B is substituted or unsubstituted C6-C60 aryl, C2-C60 heteroaryl; and Ar5 or Ar6 can form a ring with L and B; the absolute value of the difference between the lowest unoccupied molecular orbital energy level of the first electron transport material and the lowest unoccupied molecular orbital energy level of the second electron transport material ≤ 0.3 eV.

2. The organic electroluminescent device according to claim 1, wherein The dipole moment of the first electron transport material is 0 to 6 D, and the dipole moment of the second electron transport material is 4 to 15 D.

3. The organic electroluminescent device according to claim 2, wherein, The dipole moment of the first electron transport material is 0 to 1 D, and the mass ratio of the first electron transport material to the second electron transport material is 50:50 to 30:70; or the dipole moment of the first electron transport material is 2 to 6 D, and the mass ratio of the first electron transport material to the second electron transport material is 80:20 to 60:

40.

4. The organic electroluminescent device according to claim 1, characterized in that, The triplet energy level of the first electron transport material ≥ 2.35 eV; the triplet energy level of the second electron transport material ≥ 2.35 eV.

5. The organic electroluminescent device according to claim 1, characterized in that, In Formula I, X is CR5R6, O, S, NR7 or a single bond; Ar1, Ar2, Ar3, Ar4 are independently selected from H, substituted or unsubstituted monocyclic aryl, monocyclic heteroaryl, and at least one of Ar1, Ar2, Ar3, Ar4 is selected from the structure represented by Formula III: R3 and R4 are independently selected from substituted or unsubstituted monocyclic aryl, five- or six-membered monocyclic heteroaryl, a group formed by linking or condensing 2 to 3 monocyclic aryl and / or five- or six-membered monocyclic heteroaryl through a single bond, fluorenyl; The heteroatom of the monocyclic heteroaryl is selected from one or more of N, O, S, Si; X4, X5, X6 are independently selected from CH or N, and at least one is N; R5, R6, R7 are independently selected from substituted or unsubstituted C1-C6 alkyl.

6. The organic electroluminescent device according to claim 5, characterized in that, In Formula I, X is CR5R6, O, S, NR7 or a single bond; Ar1, Ar2, Ar3, and Ar4 are independently selected from H, substituted or unsubstituted phenyl, pyridyl, pyrrolyl, pyrimidinyl, pyrazinyl, triazinyl, and at least one of Ar1, Ar2, Ar3, and Ar4 is selected from the structure shown in Formula III: R3 and R4 are independently selected from substituted or unsubstituted phenyl, biphenyl, 4-pyridylphenyl, pyridyl, pyrrolyl, pyrimidinyl, pyrazinyl, triazinyl, naphthyl, anthracenyl, phenanthryl, quinolinyl, isoquinolinyl, quinoxalinyl, quinazolinyl, carbazolyl, dibenzofuranyl, dibenzothiophenyl, fluorenyl; X4, X5, and X6 are all N; R5, R6, and R7 are independently selected from substituted or unsubstituted methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl.

7. The organic electroluminescent device according to any one of claims 5 to 6, characterized in that, The substituents of Ar1, Ar2, Ar3, Ar4, R3, R4, R5, R6, and R7 are independently selected from deuterium, halogen, and C1-C6 alkyl.

8. The organic electroluminescent device according to claim 6, characterized in that, The compound shown in Formula I has any of the following structures:

9. The organic electroluminescent device according to claim 1, wherein In Formula II, X1, X2, and X3 are independently selected from CH or N, and at least one is N; R1 and R2 are independently selected from substituted or unsubstituted monocyclic aryl, five- or six-membered monocyclic heteroaryl, and groups formed by connecting or fusing 2-3 monocyclic aryl and / or five- or six-membered monocyclic heteroaryl through single bonds; The heteroatoms of the monocyclic heteroaryl are selected from one or more of N, O, S, and Si; L1 is selected from substituted or unsubstituted monocyclic aryl, five- or six-membered monocyclic heteroaryl, groups formed by connecting or fusing 2-3 monocyclic aryl and / or five- or six-membered monocyclic heteroaryl through single bonds, and fluorenyl; The heteroatoms of the monocyclic heteroaryl are selected from one or more of N, O, S, and Si; A is selected from cyano, phenyl, monocyclic heteroaryl, cyano-substituted phenyl, and cyano-substituted monocyclic heteroaryl.

10. The organic electroluminescent device according to claim 9, characterized in that, In Formula II, X1, X2, and X3 are all N; R1 and R2 are independently selected from substituted or unsubstituted phenyl and pyridyl; L1 is selected from substituted or unsubstituted phenylene, pyridylene, biphenylene, and fluorenylene; A is selected from cyano, phenyl, pyridyl, cyano-substituted phenyl, and cyano-substituted pyridyl.

11. The organic electroluminescent device according to claim 10, characterized in that, The compound shown in Formula II has any of the following structures:

12. The organic electroluminescent device according to claim 1, wherein, In the structure of Formula V, Ar5 or Ar6 is a substituted or unsubstituted monocyclic aryl, five- or six-membered monocyclic heteroaryl, a group formed by connecting or fusing 2-3 monocyclic aryl and / or five- or six-membered monocyclic heteroaryl through single bonds, or C1-C6 alkyl; The heteroatoms of the monocyclic heteroaryl are selected from one or more of N, O, S, and Si; B is a substituted or unsubstituted monocyclic aryl, five- or six-membered monocyclic heteroaryl, or a group formed by connecting or fusing 2-3 monocyclic aryl and / or five- or six-membered monocyclic heteroaryl through single bonds; The heteroatoms of the monocyclic heteroaryl are selected from one or more of N, O, S, and Si.

13. The organic electroluminescent device according to claim 12, wherein, In the structure of Formula V, Ar5 or Ar6 is a substituted or unsubstituted phenyl, naphthyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or tert-butyl; B is a substituted or unsubstituted phenyl, naphthyl, anthracenyl, bianthenyl, or phenanthryl.

14. The organic electroluminescent device according to claim 13, wherein The compound shown in Formula V has any of the following structures:

15. A display panel, comprising the organic electroluminescent device according to any one of claims 1 to 14.

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