Electronic transport material, preparation method thereof and organic electroluminescent device

Abstract

The present application relates to the technical field of organic electroluminescence devices, in particular to an electron transport material, a preparation method thereof and an organic electroluminescence device. The electron transport material is selected from a compound shown in the following formula 1: the electron transport material takes 9-phenyl-9-dibenzofuranyl fluorene ring as a mother nucleus, the fluorene ring is bonded to a cyanophenyl-substituted triazine group through a chemical bond or an arylene or heteroarylene, wherein the 9-phenyl-9-dibenzofuranyl fluorene ring ensures the spatial torsion of the molecule, avoids the poor film-forming property of the device caused by the molecular stacking; the triazine group and the cyan group have strong electron-withdrawing property, are conducive to electron transport, enhance the recombination of electrons and holes in the light-emitting layer, and thus improve the light-emitting efficiency of the device; the cyan group is bonded to the triazine group through the biphenyl group to increase the conjugation, which is more conducive to adjusting the energy level, reducing the injection barrier, reducing the driving voltage, and at the same time is also conducive to the balanced distribution of the intramolecular electrons, and further improves the light-emitting efficiency of the device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic electroluminescence devices, in particular to an electron transport material, a preparation method thereof and an organic electroluminescence device. BACKGROUND

[0002] Compared with traditional display and lighting technologies, organic electroluminescence devices (OLED) have obvious advantages, such as no need for a backlight source, light weight, low energy consumption, fast response speed, flexibility, clear display of moving images, and the like, which can meet the performance requirements of people on information display systems in many aspects.

[0003] An OLED specifically includes electrode material film layers and organic functional materials sandwiched between different electrode film layers, including a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer and an electron injection layer. The electron transport layer is a key component in the structure of the OLED, responsible for regulating the injection speed and injection amount of electrons, but the electron mobility of general organic materials is low, and the hole mobility is high, resulting in an imbalance between electrons and holes in the device, thereby reducing the efficiency and stability of the device.

[0004] In recent years, research on organic electron transport materials has been carried out, but it is still an urgent problem for those skilled in the art to develop an electron transport material with high mobility so that the OLED prepared therefrom has the performance advantages of high luminous efficiency and low driving voltage.

[0005] In view of this, the present application is proposed. SUMMARY

[0006] The purpose of the present application is to provide an electron transport material, a preparation method thereof and an organic electroluminescence device. The electron transport material provided by the embodiments of the present application can improve the luminous efficiency and reduce the driving voltage of the organic electroluminescence device.

[0007] The present application is implemented as follows:

[0008] In a first aspect, the embodiments of the present application provide an electron transport material selected from the following compound shown in formula 1:

[0009] wherein L is independently selected from any one of a functional group group formed by a chemical bond, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenyl naphthyl group, a dimethyl fluorenyl group, a phenanthryl group, a pyridyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a phenyl dibenzofuranyl group, a phenyl dibenzothiophenyl group, a naphthyl dibenzofuranyl group, a naphthyl dibenzothiophenyl group and a 9-phenyl carbazyl group;

[0010] Ar is independently selected from any one of the groups shown in the following structural formula:

[0011]

[0012] In a second aspect, the embodiments of the present application provide a preparation method of an electron transport material, which is synthesized according to the following synthesis path:

[0013]

[0014] wherein Hal and Hal1 are selected from halogen.

[0015] In a third aspect, the embodiments of the present application provide an organic electroluminescent device comprising an electron transport layer prepared by the above electron transport material.

[0016] The electron transport material provided by the embodiments of the present application has the following beneficial effects: the electron transport material provided by the embodiments of the present application takes 9-phenyl-9-dibenzofuranyl fluorene ring as a mother nucleus, and a fluorene ring is bonded to a cyanophenyl-substituted triazine group through a chemical bond or an arylene or heteroarylene group, wherein the 9-phenyl-9-dibenzofuranyl fluorene ring ensures the spatial torsion of the molecule, avoiding the poor film-forming property of the device caused by the molecular stacking; the triazine group and the cyan group have strong electron-withdrawing property, which is conducive to electron transport, enhances the recombination of electrons and holes in the light-emitting layer, and thus improves the light-emitting efficiency of the device; the cyan group is bonded to the triazine group through a biphenyl group, which increases the conjugation and is more conducive to adjusting the energy level, reducing the injection barrier, reducing the driving voltage, and also being conducive to the balanced distribution of intramolecular electrons, further improving the light-emitting efficiency of the device. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0018] Figure 1 The nuclear magnetic hydrogen spectrum of compound 7 provided for the embodiment 1 of the present application;

[0019] Figure 2 The nuclear magnetic hydrogen spectrum of compound 52 provided for the embodiment 2 of the present application;

[0020] Figure 3 The nuclear magnetic hydrogen spectrum of compound 215 provided for the embodiment 3 of the present application;

[0021] Figure 4 The nuclear magnetic hydrogen spectrum of compound 390 provided for the embodiment 4 of the present application;

[0022] Figure 5The nuclear magnetic hydrogen spectrum of compound 579 provided for the embodiment 5 of the present application is shown in the following table:

[0023] Figure 6 The nuclear magnetic hydrogen spectrum of compound 585 provided for the embodiment 6 of the present application is shown in the following table:

[0024] Figure 7 The nuclear magnetic hydrogen spectrum of compound 592 provided for the embodiment 1 of the present application is shown in the following table. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. The specific conditions not mentioned in the embodiments are carried out according to the conventional conditions or the conditions suggested by the manufacturers. The reagents or instruments not mentioned by the manufacturers are all conventional products that can be purchased in the market.

[0026] The embodiments of the present application provide an electron transport material selected from the following compound shown in formula 1:

[0027] wherein L is independently selected from any one of the functional group group consisting of a chemical bond, a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenyl naphthyl group, a dimethyl fluorenyl group, a phenanthryl group, a pyridyl group, a dibenzofuranyl group, a dibenzothiophenyl group, a phenyl dibenzofuranyl group, a phenyl dibenzothiophenyl group, a naphthyl dibenzofuranyl group, a naphthyl dibenzothiophenyl group and a 9-phenyl carbazyl group; preferably, L is selected from any one of a chemical bond, a phenyl group or a biphenyl group.

[0028] Ar is independently selected from any one of the groups shown in the following structural formula:

[0029]

[0030] Preferably, Ar is independently selected from any one of the groups shown in the following structural formula:

[0031]

[0032] It should be noted that * in the above structural formula represents a connection site.

[0033] Further, the electron transport material is selected from any one of the compounds shown in the following structural formula:

[0034]

[0035] wherein R represents hydrogen or cyano. The electron transport material is selected from any one of the compounds shown in the following structural formula:

[0036]

[0037]

[0038]

[0039]

[0040]

[0041] More specifically, the electron transport material is selected from any one of the compounds represented by the following structural formula:

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075] The electronic transport material provided by the embodiment of the present application ensures the spatial torsion of the 9-phenyl-9-dibenzofuranyl fluorene ring of the molecule, avoids the poor film-forming property of the device caused by the molecular stacking; the triazine group and the cyano group have strong electron-withdrawing property, which is beneficial to the electronic transport, enhances the recombination of the electron and the hole in the light-emitting layer, and thus improves the light-emitting efficiency of the device; the cyano group is bonded to the triazine group through the biphenyl group, which increases the conjugation and is more beneficial to the adjustment of the energy level, reduces the injection barrier, reduces the driving voltage, and is also beneficial to the balanced distribution of the intramolecular electron, and further improves the light-emitting efficiency of the device.

[0076] In a second aspect, the embodiment of the present application provides a preparation method of the above electronic transport material, which synthesizes the electronic transport material according to the following synthesis path:

[0077] Hal and Hal1 are selected from halogen, for example, are selected from any one of Cl, Br and I.

[0078] Specifically, the first step: under nitrogen protection, the reactant 1 (1.0 eq), the reactant 2 (1.1-1.3 eq), the palladium catalyst (0.05-0.1 eq) and potassium acetate (2.0-3.0 eq) are dissolved in a mixed solvent of N,N-dimethylformamide (DMF), heated to 85-95℃, and reacted for 8-12h. The solvent is removed using a rotary evaporator, the residue is added to dichloromethane, stirred, filtered, and purified by column chromatography to obtain intermediate 1.

[0079] The second step: under nitrogen protection, intermediate 1 (1.0 eq), reactant 3 (1.1-1.3 eq), palladium catalyst (0.01-0.02 eq) and phosphine ligand (0.02-0.05 eq), base (2.0-2.3 eq) are added to a mixed solvent of toluene, ethanol, water (volume ratio 2-4:1:1) respectively, heated to 80-100℃, reacted for 8-12h, cooled to room temperature, added with H2O, and after the solid is completely precipitated, the filter cake is dried, the obtained solid is dissolved by heating with toluene, and the hot solution is passed through a silica gel funnel with methanol:dichloromethane (volume ratio 1:40-60) as the developing agent, the filtrate is removed by rotary evaporator, and the obtained solid is dried to obtain the compound of formula 1.

[0080] The palladium catalyst can be any one of Pd2(dba)3, Pd(PPh3)4, PdCl2, PdCl2(dppf), Pd(OAc)2, Pd(PPh3)2Cl2 and NiCl2(dppf);

[0081] The phosphine ligand can be any one of P(t-Bu)3, X-phos, PET3, PMe3, PPh3, KPPh2 and P(t-Bu)2Cl;

[0082] The base can be any one of K2CO3, K3PO4, Na2CO3, CsF, Cs2CO3 or t-BuONa.

[0083] In a third aspect, the embodiments of the present application also provide an organic electroluminescent device, which comprises an anode, a cathode and an organic thin film layer arranged between the anode and the cathode, and the organic thin film layer comprises an electron transport layer, wherein the compound of formula 1 prepared by the present application is used as the electron transport layer material to prepare the electron transport layer.

[0084] The organic thin film layer can specifically comprise any one or a combination of at least two of a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting auxiliary layer, a light-emitting layer, a hole blocking layer, an electron injection layer and a cap layer.

[0085] The anode is made of a conductor with a high work function to help hole injection, such as a metal, a metal oxide and / or a conductive polymer. The metal can be selected from nickel, platinum, vanadium, chromium, copper, zinc, gold, silver or an alloy thereof; the metal oxide can be selected from zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide; the combination of a metal and an oxide can be selected from ZnO and Al or SnO2 and Sb or ITO and Ag; the conductive polymer can be selected from poly(3-methylthiophene), poly(3,4-(ethylen-1,2-dioxy)thiophene), polypyrrole and polyaniline, but is not limited thereto.

[0086] The hole injection layer and the hole transport layer efficiently inject or transport holes from the anode between the electrodes to which an electric field has been supplied. Desirably, the hole injection efficiency is high and the injected holes are efficiently transported. Therefore, a material with a small ionization potential and a large hole mobility, and further excellent stability, which is not easily contaminated with impurities during manufacture and use, is preferred. The hole injection layer is preferably a p-doped hole injection layer; the hole transport material can be selected from arylamine derivatives, conductive polymers, and block copolymers having both a conjugated portion and a non-conjugated portion.

[0087] A light-emitting auxiliary layer (a multi-layer hole transport layer) is interposed between the hole transport layer and the light-emitting layer, which functions to smoothly move the holes from the anode to the light-emitting layer and to block the electrons from the cathode.

[0088] The light-emitting layer is a compound that emits light by being excited by the recombination of holes and electrons, and is preferably a compound that can form a stable thin film shape and exhibits strong light-emitting efficiency in a solid state. The light-emitting layer can be a single layer or a plurality of layers, and can include a host material and a dopant material. The amounts of the host material and the dopant material are determined in accordance with the properties of the respective materials. As a doping method, co-evaporation with the host material or simultaneous evaporation after mixing with the host material can be used.

[0089] The electron transport layer and the electron injection layer efficiently transport or inject electrons from the cathode between the electrodes to which an electric field has been supplied. A material with a large electron affinity, a large electron mobility, excellent stability and a small tendency to produce impurities is preferred.

[0090] The cathode is a material that can efficiently inject electrons, and can be selected from the same materials as the anode. If a metal with a low work function that helps efficient electron injection is selected, a small amount of lithium, cesium or magnesium, etc. is usually doped to avoid instability in the atmosphere.

[0091] The OLED device is not particularly limited in terms of the materials of other layers, except that the electron transport layer contains the compound of Formula 1.

[0092] The features and properties of the present application are further described in detail below with reference to examples.

[0093] Example 1

[0094] The present application provides a preparation method of an electron transport material (compound 7), which is synthesized by referring to the following synthesis path:

[0095] Specifically as follows:

[0096] The reactant 1-7 (20 mmol, CAS: 2237935-99-6), the reactant 2-7 (25 mmol), Pd(PPh3)4 (1.0 mmol) and potassium acetate (4.0 mmol) were dissolved in a mixed solvent of DMF under nitrogen protection, and the temperature was raised to 90°C, and the reaction was carried out for 10 h. The solvent was removed by using a rotary evaporator, the residue was added into dichloromethane for stirring, filtration and purification by column chromatography, and the intermediate 1-7 (8.02 g in mass, yield: 75%, test value MS (ESI, m / Z): [M+H] = 534.59, the mass spectrometer model was Waters XEVO TQD, low precision, and the test was carried out by using an ESI source) was obtained. +

[0097] The intermediate 1-7 (20 mmol), the reactant 3-7 (25 mmol, CAS: 2260561-71-3), Pd(PPh3)2Cl2 (0.2 mmol) and X-phos (0.4 mmol), K2CO3 (4.0 mmol) were respectively added into a mixed solvent of toluene, ethanol and water (150 mL:50 mL:50 mL) under nitrogen protection, the temperature was raised to 95°C, the reaction was carried out for 10 h, and the temperature was cooled to room temperature, H2O was added, the solid was precipitated, and then the filtration was carried out, the filter cake was dried, the obtained solid was dissolved by heating with toluene, the hot silica gel funnel was used with methanol:dichloromethane (volume ratio was 1:4) as a developing agent, the filtrate was removed by using a rotary evaporator, the obtained solid was dried, and the compound 7 (8.31 g in mass, yield: 56%) was obtained.

[0098] Characterization: (1) the nuclear magnetic resonance hydrogen spectrum of the compound 7 was as shown in the following formula: Figure 1

[0099] (2) HPLC purity: >99.8%.

[0100] (3) elemental analysis: theoretical value: C, 85.92; H, 4.35; N, 7.56; O, 2.16; test value: C, 85.84; H, 4.41; N, 7.58; O, 2.19.

[0101] (4) MS (ESI, m / Z): [M+H] + = 741.89. ​​

[0102] Example 2

[0103] The present embodiment provides a preparation method of an electron transport material (compound 52), which is synthesized by referring to the following synthesis path:

[0104] Specifically as follows:

[0105] The synthesis method and the amount provided by the present embodiment are the same as those of the method for synthesizing compound 7 provided by example 1, and the difference is that the reactant 1-7 and the reactant 3-7 are replaced by the reactant 1-52 (CAS: 2767222-21-7) and the reactant 3-52 (CAS: 2817692-03-6) respectively, so as to obtain the compound 52 (mass: 10.62 g, yield: 63%).

[0106] Characterization: (1) The nuclear magnetic resonance hydrogen spectrum of compound 52 is as shown in the following figure: Figure 2 .

[0107] (2) HPLC purity: > 99.8%.

[0108] (3) Elemental analysis: Theoretical value: C, 85.59; H, 4.19; N, 8.32; O, 1.90; Test value: C, 85.56; H, 4.24; N, 8.33; O, 1.93.

[0109] (4) MS (ESI, m / Z): [M+H] + = 843.05.

[0110] Example 3

[0111] The present embodiment provides a preparation method of an electron transport material (compound 215), which is synthesized by referring to the following synthesis path:

[0112] Specifically as follows:

[0113] The synthesis method and the amount provided by the present embodiment are the same as those of the method for synthesizing compound 7 provided by example 1, and the difference is that the reactant 1-7 and the reactant 3-7 are replaced by the reactant 1-215 (CAS: 2883197-30-4) and the reactant 3-215 (CAS: 2883453-96-9) respectively, so as to obtain the compound 215 (mass: 10.79 g, yield: 66%).

[0114] Characterization: (1) The nuclear magnetic resonance hydrogen spectrum of compound 215 is as shown in the following figure: Figure 3 .

[0115] (2) HPLC purity: > 99.8%.

[0116] (3) Elemental analysis: Theoretical value: C, 86.74; H, 4.44; N, 6.86; O, 1.96; Test value: C, 86.68; H, 4.49; N, 6.88; O, 2.00.

[0117] (4) MS (ESI, m / Z): [M+H] + = 817.10.

[0118] Example 4

[0119] The present embodiment provides a preparation method of an electron transport material (compound 390), which is synthesized by referring to the following synthesis path:

[0120] Specifically as follows:

[0121] The synthesis method and the amount provided by the present embodiment are the same as the method of synthesizing compound 7 provided by Example 1, and the difference is that reactant 1-7 and reactant 3-7 are respectively replaced by reactant 1-390 (CAS: 2237936-00-2) and reactant 3-390 (CAS: 2506373-46-0) to obtain compound 390 (mass: 12.34 g, yield: 69%).

[0122] Characterization: (1) The proton nuclear magnetic resonance spectrum of compound 390 is as shown in the following figure. Figure 4

[0123] (2) HPLC purity: > 99.8%.

[0124] (3) Elemental analysis: Theoretical value: C, 87.42; H, 4.51; N, 6.27; O, 1.79; Test value: C, 87.39; H, 4.55; N, 6.28; O, 1.81.

[0125] (4) MS (ESI, m / Z): [M+H] + = 894.08.

[0126] Example 5

[0127] The present embodiment provides a preparation method of an electron transport material (compound 579), which is synthesized by referring to the following synthesis path:

[0128] Specifically as follows:

[0129] ​The synthetic method and the amount provided in the embodiment are the same as the method for synthesizing compound 7 provided in embodiment 1, and the difference is that reactant 1-7 and reactant 3-7 are replaced by reactant 1-579 (CAS: 2359605-29-9) and reactant 3-579 (CAS: 2763214-56-6) respectively to obtain compound 579 (mass is 11.33 g, yield: 60%).

[0130] Characterization: (1) The nuclear magnetic resonance hydrogen spectrum of compound 579 is as shown in the following figure. Figure 5

[0131] (2) HPLC purity: > 99.8%.

[0132] (3) Elemental analysis: Theoretical value: C, 87.87; H, 4.49; N, 5.94; O, 1.70; Test value: C, 87.82; H, 4.53; N, 5.96; O, 1.73.

[0133] (4) MS (ESI, m / Z): [M+H] + = 944.16.

[0134] Embodiment 6

[0135] The embodiment of the application provides a preparation method of an electron transport material (compound 585), which is synthesized by referring to the following synthesis path:

[0136] Specifically as follows:

[0137] The synthetic method and the amount provided in the embodiment are the same as the method for synthesizing compound 7 provided in embodiment 1, and the difference is that reactant 1-7 and reactant 3-7 are replaced by reactant 1-52 and reactant 3-585 (CAS: 2857863-24-0) respectively to obtain compound 585. (mass is 10.09 g, yield: 54%).

[0138] Characterization: (1) The nuclear magnetic resonance hydrogen spectrum of compound 585 is as shown in the following figure. Figure 6

[0139] (2) HPLC purity: > 99.8%.

[0140] (3) Elemental analysis: Theoretical value: C, 87.53; H, 4.75; N, 6.00; O, 1.71; Test value: C, 87.48; H, 4.79; N, 6.01; O, 1.74.

[0141] (4) MS (ESI, m / Z): [M+H] + = 934.15.

[0142] ​​Example 7

[0143] The present embodiment provides a preparation method of an electron transport material (compound 592), which is synthesized by referring to the following synthesis path:

[0144] The specific process is as follows:

[0145] The synthesis method and the amount provided by the present embodiment are the same as those of the method for synthesizing compound 7 provided by Example 1, and the difference is that the reactant 1-7 and the reactant 3-7 are replaced by the reactant 1-592 (CAS: 2237935-98-5) and the reactant 3-592 (CAS: 2498901-93-0) respectively to obtain compound 592. (mass: 10.28 g, yield: 51%).

[0146] Characterization: (1) The proton nuclear magnetic resonance spectrum of compound 592 is as shown in the following figure. Figure 7

[0147] (2) HPLC purity: >99.8%.

[0148] (3) Elemental analysis: theoretical value: C, 85.86; H, 4.20; N, 8.34; O, 1.59; test value: C, 85.82; H, 4.24; N, 8.35; O, 1.62.

[0149] (4) MS (ESI, m / Z): [M+H] + = 1008.18.

[0150] Examples 8-158

[0151] The synthesis of the following compounds is completed by referring to the synthesis methods of Examples 1 to 7, and the mass spectrometer with the model number of Waters XEVOTQD is used for testing, the accuracy is low, and the ESI source is used for testing, and the mass spectrometry test values of the compounds are shown in the following Table 1.

[0152] Table 1 Mass spectrometry of Examples 8-158

[0153]

[0154]

[0155]

[0156] In addition, other compounds of the present application can be obtained by referring to the synthesis methods of the above-mentioned examples, so they are not listed one by one here.

[0157] The following will specifically describe an organic electron transport material and an organic electroluminescent device provided by the present application in combination with specific examples. ​

[0158] Device Example 1

[0159] This example provides a preparation of an organic electroluminescence device, in which the structure of the prepared OLED device is: ITO anode / HIL / HTL / Prime / EML / HBL / ETL / EIL / cathode / light extraction layer. The specifics are as follows:

[0160] a. ITO anode: ITO (indium tin oxide)-Ag-ITO (indium tin oxide) glass substrate with a coating thickness of 1200 nm was cleaned twice in distilled water, ultrasonic washing for 30 min, and then repeatedly cleaned twice with distilled water, ultrasonic washing for 10 min. After washing, methanol, acetone, and isopropanol were sequentially ultrasonic washed (5 min each time), dried, and then transferred to a plasma cleaning machine for washing for 5 min, and then sent to an evaporation machine. The substrate was used as an anode, and other functional layers were sequentially evaporated thereon. b. HIL (hole injection layer): The hole injection layer materials HT and P-dopant were vacuum evaporated at an evaporation rate of 0.1 nm / s, and the chemical formula is shown below. The evaporation rate ratio of HT and P-dopant was 97:3, and the thickness was 10 nm.

[0161] c. HTL (hole transport layer): The HT was vacuum evaporated on the hole injection layer as a hole transport layer at an evaporation rate of 0.1 nm / s to a thickness of 120 nm.

[0162] d. Prime (light-emitting auxiliary layer): The Prime was vacuum evaporated on the hole transport layer as a light-emitting auxiliary layer at an evaporation rate of 0.1 nm / s to a thickness of 5 nm. e. EML (emitting layer): Then, the host material (Host) and the dopant material (Dopant) were vacuum evaporated on the above light-emitting auxiliary layer as an emitting layer at an evaporation rate of 0.1 nm / s to a thickness of 30 nm, and the chemical formula of Host and Dopant is shown below. The evaporation rate ratio of Host and Dopant was 98:2.

[0163] f. HBL (hole blocking layer): The hole blocking layer HB was vacuum evaporated at an evaporation rate of 0.1 nm / s to a thickness of 5 nm.

[0164] g. ETL (electron transport layer): Compound 7 and Liq were vacuum evaporated as an electron transport layer at an evaporation rate of 0.1 nm / s to a thickness of 30 nm. The evaporation rate ratio of Compound 7 and Liq was 50:50.

[0165]

[0166] ​​​​​​​

[0167] h、EIL (electron injection layer): Yb film layer 1.0 nm was evaporated at an evaporation rate of 0.1 nm / s to form an electron injection layer.

[0168] i、Cathode: Magnesium and silver 13 nm were evaporated at an evaporation rate ratio of 1:9 to obtain an OLED device.

[0169] j、Light extraction layer: CPL with a thickness of 70 nm was vacuum evaporated on the cathode as a light extraction layer at an evaporation rate of 0.1 nm / s.

[0170] K、Subsequently, the substrate on which evaporation was completed was encapsulated. First, the cleaned cover plate was coated with UV glue using a gluing device, then the coated cover plate was moved to the pressing section, the substrate on which evaporation was completed was placed on the end of the cover plate, and finally the substrate and the cover plate were bonded under the action of the bonding device, and the UV glue was cured by light at the same time.

[0171]

[0172] Device Example 2-158:

[0173] The organic electroluminescent device of Application Example 2-158 was prepared according to the preparation method of the organic electroluminescent device provided in Device Example 1 above, except that the compound 7 in Device Example 1 was replaced by the corresponding compound in Example 2-158 to form an electron transport layer.

[0174] Device Comparative Example 1-14:

[0175] The organic electroluminescent device of Comparative Example 1-14 was prepared according to the preparation method of the organic electroluminescent device provided in Device Example 1 above, except that the compound 7 in Device Example 1 was replaced by Comparative Compound 1-14 to form an electron transport layer.

[0176] Among them, the structural formula of Comparative Compound 1-14 is as follows:

[0177]

[0178] The driving voltage, BI value and luminous efficiency of the organic electroluminescent devices obtained by the above Device Examples 1-158 and Device Comparative Example 1-14 were characterized at a brightness of 1000 (nits), and the test results are as follows Table 2:

[0179] Table 2

[0180]

[0181] ​​​

[0182]

[0183]

[0184]

[0185]

[0186]

[0187] Note: BI in Table 2 = luminous efficiency / CIEy, which reflects the influence of colorimetric on luminous efficiency in blue OLED devices.

[0188] From Table 2, it can be seen that the OLED devices prepared by using the compound having the specific structural formula provided by the embodiment of the present application as the electron transport material (device examples 1-158) and the OLED devices prepared by using the existing materials provided by device comparative examples 1-14, the driving voltage of the organic electroluminescent device prepared by the compound of general formula 1 of the present application is reduced by 0.05-0.27 eV compared with the organic electroluminescent device of the comparative example, the luminous efficiency is increased by 4%-17% compared with the device example 1 provided by the comparative example, and the BI value is also improved.

[0189] Among them, the difference between comparative compound 4 and compound 66 is whether the biphenyl group is substituted by cyano, and the introduction of strong electron-withdrawing group on the biphenyl group makes the electron distribution more balanced, which is beneficial to improve the mobility, so that the prepared organic electroluminescent device is significantly improved in luminous efficiency. As can be seen from Table 2, the luminous efficiency of compound 66 is increased by 11% compared with comparative compound 4, and the driving voltage is reduced by 0.12 eV. The device performance has been significantly improved in the field.

[0190] The difference between comparative compound 5 and compound 119 is the position of cyano. The cyano in comparative compound 5 is connected to the dibenzofuran group through the phenyl group, while the cyano in compound 119 is introduced to the triazine group through the biphenyl group, so that the charge distribution of compound 119 is more balanced. The polarization degree of the molecule in comparative compound 5 is easy to increase, and the mobility is slow. As can be seen from Table 2, the luminous efficiency of compound 119 is increased by 8% compared with comparative compound 5.

[0191] Comparing comparative compound 6 with compound 120, the introduction of dibenzofuran in fluorene ring is beneficial to electron transport, at the same time reduces the uneven distribution of intramolecular charge, avoids the bipolarity of the molecule, enhances the electron transport ability, and improves the luminous efficiency of the device. As can be seen from Table 2, the luminous efficiency of compound 120 is increased by 13% compared with comparative compound 6.

[0192] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. An electron transport material, characterized by, which is selected from the group consisting of compounds of the following Formula 1: wherein L is independently selected from any one of a group of functional groups formed by a chemical bond, phenyl, biphenyl, terphenyl, naphthyl, phenylnaphthyl, dimethylfluorenyl, phenanthryl, pyridyl, dibenzofuranyl, dibenzothiophenyl, phenyldibenzofuranyl, phenyldibenzothiophenyl, naphthyldibenzofuranyl, naphthyldibenzothiophenyl, and 9-phenylcarbazolyl; Ar is independently selected from any one of the following structural formulae: 。 2. The electron transport material according to claim 1, characterized in that, L is independently selected from any one of the group consisting of a chemical bond, a phenyl group and a biphenyl group.

3. The electron transport material according to claim 1, wherein Ar is independently selected from any one of the following structural formulae: 。 4. The electron transport material according to claim 1, wherein The electron transport material is selected from any one of the following structural formulae: wherein R represents hydrogen or cyano.

5. The electron transport material according to claim 1, wherein The electron transport material is selected from any one of the following structural formulae: 。 6. An electron transport material, characterized in that, The electron transport material is selected from any one of the following structural formulae: 。 7. A method of preparing the electron transport material of claim 1, wherein The electron transport material is synthesized according to the following synthesis path: wherein Hal and Hal1are selected from halogen.

8. The preparation method according to claim 7, characterized in that Hal and Hal1 are selected from any one of Cl, Br and I.

9. The production method according to claim 7, characterized by, Comprising: The reactant 1, the reactant 2 and the palladium catalyst are mixed to react, wherein the reaction temperature is 85-95℃, and the reaction time is 8-12h; The palladium catalyst comprises any one of Pd2(dba)3, Pd(PPh3)4, PdCl2, PdCl2(dppf), Pd(OAc)2, Pd(PPh3)2Cl2 and NiCl2(dppf); The molar ratio of the reactant 1, the reactant 2 and the palladium catalyst is 1:1.1-1.3:0.05-0.1; Comprising: the intermediate 1, the reactant 3, the palladium catalyst and the phosphine ligand are mixed to react, wherein the reaction temperature is 80-100℃, and the reaction time is 8-12h; The phosphine ligand is selected from any one of P(t-Bu)3, X-phos, PET3, PMe3, PPh3, KPPh2 and P(t-Bu)2Cl; The molar ratio of the intermediate 1, the reactant 3, the palladium catalyst and the phosphine ligand is 1:1.1-1.3:0.01-0.02:0.02-0.

05.

10. An organic electroluminescent device, characterized by It comprises an electron transport layer prepared by the electron transport material of claim 1.

Images