Electron injection material and OLED (Organic Light Emitting Diode)

Abstract

The invention relates to the technical field of preparation of organic photoelectric materials, in particular to an electron injection material and an OLED (Organic Light Emitting Diode). An electron injection layer material containing an N atom group is used as a main body material and is subjected to co-evaporation with low-work function metal to form an electron injection layer; the compound containing the N atom group in the main body material binds the low work function metal, so that the stability of the metal in the electron injection layer is improved, the interface bonding effect between the cathode and the electron transmission layer is optimized, the active metal content of the electron injection layer is reduced, the layering influence between the organic layer and the metal is reduced, and the performance of the device is improved. And the device life and luminous efficiency are improved.

Description

[0001] This application is a divisional application of the invention patent application filed on December 4, 2023, with application number "202311677388.4" and titled "An Electron Injection Material and an OLED Organic Electroluminescent Device". Technical Field

[0002] This invention relates to the field of organic optoelectronic material preparation technology, and in particular to an electron injection material and an OLED organic electroluminescent device. Background Technology

[0003] OLED is a popular display technology today, boasting advantages such as self-emissiveness, ultra-thinness, wide viewing angle, fast response speed, low power consumption, and flexible display. In traditional single-layer devices, the material of the emissive layer not only emits light but also performs the functions of electron and hole transport. However, the materials used for the emissive layer generally do not have excellent electron transport properties, and organic materials that simultaneously possess both electron and hole transport layer characteristics are rare, meaning they can only transport one type of electron or hole. Therefore, the resulting single-layer devices exhibit an imbalance between electron and hole injection and transport, leading to poor luminous efficiency. In recent years, with the development of OLED display technology, higher performance requirements have been continuously raised, and device structures are constantly evolving.

[0004] To generate suitable step energy levels for better carrier transport, existing multilayer device structures add functional layers such as electron / hole injection layers and electron / hole transport layers on top of the light-emitting layer. Among these, the electron injection layer material is often directly composed of a thin layer of reactive metal (such as YB, Li, etc.), but the adhesion between the metal layer and the organic layer is poor, the interfacial bonding is weak, and the device lifetime is relatively poor. Furthermore, using a thin metal layer increases the extinction coefficient and reduces the device's luminous efficiency. Therefore, finding a high-performance electron injection layer material is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing an electron injection material and an OLED organic electroluminescent device. This invention utilizes a specific electron injection material co-deposited with a low work function metal to form an electron injection layer. This process, when used to fabricate an organic device, reduces interfacial bonding between the organic layer and the cathode / electron transport layer, minimizes the delamination between the organic layer and the metal, and improves device lifetime and luminous efficiency.

[0006] To achieve the objectives of this invention, the technical solution is as follows: According to one or more embodiments, the present invention provides an electron injection material compound having the general formula structure shown in formula (I) or formula (II): ; In formula (I) or formula (II), L is selected from C1-C20 alkyl, C3-C30 fused heteroalkyl, C6-C30 aryl, C5-C30 heteroaryl, C6-C30 fused aryl, C5-C30 fused heteroaryl, and the group consisting thereof; the heteroatom is an O, S or N atom; R1-R3 are each independently selected from hydrogen, deuterium, C6-C30 aryl, C5-C30 N heteroaryl, and the group consisting thereof.

[0007] According to one or more embodiments, L in formula (I) or formula (II) is selected from phenyl, naphthyl, anthracene, pyridyl, quinolinyl, dibenzofuranyl, dibenzothiophene, or dimethylfluorenyl.

[0008] According to one or more embodiments, R1-R3 in formula (I) or formula (II) are each independently selected from hydrogen, deuterium, phenyl, naphthyl or pyridyl.

[0009] According to one or more embodiments, the electron-injection material compound is selected from any of the following chemical structures: .

[0010] In another aspect, the present invention also provides the application of electron injection material compounds with general structures as shown in formula (I) or formula (II) above in the fabrication of electronic devices.

[0011] Furthermore, the electronic devices include organic photovoltaic devices, organic light-emitting devices (OLEDs), organic integrated circuits (O-ICs), organic field-effect transistors (O-FETs), organic light-emitting transistors (O-LETs), organic solar cells (O-SCs), organic optical detectors, organic photosensors, organic field quenching devices (O-FQDs), light-emitting electrochemical cells (LECs), and organic laser diodes (O-lasers).

[0012] In another aspect, the present invention also provides an organic electroluminescent device comprising a cathode, an anode, and at least one organic functional layer therebetween; wherein the organic functional layer comprises an electron injection layer comprising an electron injection material compound having a general structure as shown in Formula (I) or Formula (II) above.

[0013] Furthermore, the electron injection layer is also doped with a low work function metal material, which is selected from one or more of silver, ytterbium, and magnesium.

[0014] The doping amount of the low work function metal material in the electron injection layer is 1-5%.

[0015] According to one or more embodiments, the low work function metal material is ytterbium metal with a doping amount of 2%-2.5%.

[0016] According to one or more embodiments, the thickness of the electron injection layer in the organic electroluminescent device is 50-150 Å.

[0017] In another aspect, the present invention also provides an organic optoelectronic device, comprising a substrate layer, a first electrode, a second electrode facing the first electrode, and an electron injection layer disposed between the first electrode and the second electrode; wherein the luminescent material layer comprises an electron injection material compound having a general structure as shown in Formula (I) or Formula (II) above.

[0018] The present invention also provides a composition comprising an electron-injection material compound having a general structure as shown in formula (I) or formula (II) above.

[0019] The present invention also provides a formulation comprising an electron-injected material compound having the general structure shown in formula (I) or formula (II) above, or a composition as described above, and at least one solvent. The solvent is not particularly limited and may be any solvent well known to those skilled in the art, such as unsaturated hydrocarbon solvents like toluene, xylene, mesitylene, tetrahydronaphthalene, decahydronaphthalene, dicyclohexane, n-butylbenzene, sec-butylbenzene, tert-butylbenzene, carbon tetrachloride, chloroform, dichloromethane, dichloroethane, chlorobutane, bromobutane, chloropentane, bromopentane, chlorohexane, bromohexane, chlorocyclohexane, bromocyclohexane, etc.; halogenated unsaturated hydrocarbon solvents like chlorobenzene, dichlorobenzene, trichlorobenzene, etc.; ether solvents like tetrahydrofuran, tetrahydropyran, etc.; and ester solvents like alkyl benzoates.

[0020] The present invention also provides a display or lighting device comprising one or more of the organic electroluminescent devices described above.

[0021] Compared with the prior art, the present invention has the following beneficial effects: This invention uses an electron injection layer material containing nitrogen atom groups as the main material, which is co-deposited with a low work function metal to form an electron injection layer. The compound containing nitrogen atom groups in the main material binds the low work function metal, thereby improving the stability of the metal in the electron injection layer, optimizing the interfacial bonding between the metal and the cathode and electron transport layer, reducing the content of active metal in the electron injection layer, reducing the impact of delamination between the organic layer and the metal, and improving device lifespan and luminous efficiency. Attached Figure Description

[0022] Figure 1This is a schematic diagram of the structure of the OLED device provided in Embodiment 1 of the present invention. Detailed Implementation

[0023] The present invention will now be described in detail. The descriptions of the constituent elements described below are sometimes based on representative embodiments or specific examples of the invention, but the invention is not limited to such embodiments or specific examples. This disclosure can be more readily understood by referring to the following detailed descriptions and the examples contained therein. Before disclosing and describing the compounds, devices, and / or methods of the present invention, it should be understood that, unless otherwise stated, they are not limited to specific synthetic methods or specific reagents, as these can vary. It should also be understood that the terminology used in this invention is for describing particular aspects only and is not intended to be limiting. Although any similar or equivalent methods and materials described in this invention can be used in this practice or experiment, exemplary methods and materials are now described.

[0024] Preparation Example Preparation Example 1: Synthesis of Compounds 1-2 The synthesis route is shown below: ; 64 mmol of compound 1-2-1 was dissolved in 130 mL of 1,4-dioxane, followed by the addition of 33 mmol of 1-1-2, 1.5 mmol of tetraphenylphosphine palladium, and 93 mmol of potassium carbonate. The mixture was stirred at 100 °C for 6 h. After the reaction was terminated, the product was cooled to 25 °C and extracted with distilled water and ethyl acetate. The organic layer was dried over anhydrous magnesium sulfate, filtered, and concentrated. The concentrated residue was purified by column chromatography using ethyl acetate and hexane as the developing solvent to obtain target compound 1-2. The structure of target compound 1-2 was determined by liquid chromatography-mass spectrometry (LC-MS) (m / z)(M+): theoretical value 586.22, measured value 586.56.

[0025] Preparation Example 2: Synthesis of Compounds 1-4 Compounds 1-4 were synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 686.25, measured value 686.75.

[0026] Preparation Example 3: Synthesis of Compounds 1-5 Compounds 1-5 were synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 588.21, test value 588.60.

[0027] Preparation Example 4: Synthesis of Compounds 1-11 The synthesis route is shown below: ;

[0028] Compound 1-11 was synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 587.21, measured value 587.53.

[0029] Preparation Example 5: Synthesis of Compounds 1-12 Compounds 1-12 were synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 637.23, measured value 637.77.

[0030] Preparation Example 6: Synthesis of Compounds 1-13 Compounds 1-13 were synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 636.23, measured value 636.65.

[0031] Preparation Example 7: Synthesis of Compounds 1-17 Compounds 1-17 were synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 686.25, measured value 686.83.

[0032] Preparation Example 8: Synthesis of Compounds 1-20 Compounds 1-20 were synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 702.28, measured value 702.69.

[0033] Preparation Example 9: Synthesis of Compounds 1-22 Compounds 1-22 were synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 692.20, measured value 692.65.

[0034] Preparation Example 10: Synthesis of Compounds 1-23 Compounds 1-23 were synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 704.27, test value 704.73.

[0035] Preparation Example 11: Synthesis of Compounds 1-26 Compounds 1-26 were synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 676.23, measured value 676.66.

[0036] Preparation Example 12: Synthesis of Compounds 1-28 Compound 1-28 was synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 702.28, measured value 702.66.

[0037] Preparation Example 13: Synthesis of Compound 2-1 The synthesis route is shown below: ;

[0038] Compound 2-1 was synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 562.22, measured value 562.71.

[0039] Preparation Example 14: Synthesis of Compounds 2-9 Compounds 2-9 were synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 411.15, measured value 411.57.

[0040] Preparation Example 15: Synthesis of Compound 2-10 Compound 2-10 was synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 563.21, measured value 563.75.

[0041] Preparation Example 16: Synthesis of Compounds 2-13 Compound 2-13 was synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 654.22, measured value 654.68.

[0042] Preparation Example 17: Synthesis of Compounds 2-19 Compound 2-19 was synthesized according to the synthesis steps and reaction conditions of Preparation Example 1. The results of LC-MS (m / z)(M+) analysis by liquid chromatography-mass spectrometry were as follows: theoretical value 670.19, measured value 670.53.

[0043] Example This invention discloses an OLED device structure, as detailed below: An OLED device structure, the schematic diagram of which is shown below. Figure 1 As shown, it includes, in sequence: substrate layer 1, second electrode layer 2, organic light-emitting functional layer 3, first electrode layer 4, and cover layer 5. The organic light-emitting functional layer 3 is composed of hole injection layer 31, hole transport layer 32, light-emitting layer 33, electron transport layer 34, and electron injection layer 35 from bottom to top.

[0044] The manufacturing process of OLED devices: First, the alkali-free glass substrate was cleaned with isopropanol for 15 minutes using an ultrasonic cleaner, followed by 30 minutes of UV ozone cleaning in air. The treated substrate was then subjected to vacuum evaporation. First, an ITO / Ag / ITO layer of 100nm was deposited as the second electrode layer 2. Then, a hole injection layer 31 (rate ratio HT:PD = 97:3, 10nm), a hole transport layer 32 (HT, 30nm), a blue emitting layer 33 (body BH and doped BD (rate ratio BH:BD = 98:2, 20nm)), an electron transport layer 34 (rate ratio ET:Liq = 1:1, 35nm), and an electron injection layer 35 (body materials 1-2 and doped metal Yb (doping ratio 2.5%), 5nm) were sequentially deposited. Finally, Mg and Ag (rate ratio 1:9, 13nm) were co-deposited to form a semi-transparent cathode, i.e., the first electrode layer 4. Then, a compound CPL (70nm) was deposited as the capping layer 5. Finally, the light-emitting device was encapsulated using epoxy resin adhesive under a nitrogen atmosphere, which is recorded as Example 1. The molecular structural formulas of the relevant materials are shown below: .

[0045] Following the method provided in Example 1, OLED devices were fabricated using the electron injection layer materials listed in Table 1 as substitutes for compound 1-2+Yb(2.5%) in Example 1, and are designated as Examples 2-22 and Comparative Examples 1-3. The molecular structure of comparative compound 1 is shown below: .

[0046] Performance testing Experiment 1: Optical performance testing of the device was conducted using the CS2000; Experiment 2: Lifetime performance testing of the device was conducted using a lifetime tester. The performance test results of the device are shown in Table 1.

[0047] Table 1. Device luminescence characteristics data

[0048] As shown in Table 1, compared with Comparative Examples 1-3, Examples 1 to 22 exhibited superior device performance in terms of driving voltage, current efficiency, and lifetime. The performance improvements in each device application example are based on the fact that the N-structured electron injection material of this invention reduces the interfacial bonding between it and the cathode and electron transport layer, and minimizes the delamination effect between the organic layer and the metal. Furthermore, co-depositing it with a low work function metal to form an electron injection layer for electronic device fabrication, especially devices fabricated after doping with 1-5% low work function metal, achieves higher current efficiency and lifetime while reducing the driving voltage. This indicates that the electron injection material provided by this invention has certain commercial application value.

[0049] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. An electron injection material compound, characterized by, The electron injection material compound has a general structure shown in the following formula (I): ； In formula (I), L is selected from naphthyl, anthracenyl, pyridyl, quinolyl, dibenzofuranyl, dibenzothiophenyl or dimethylfluorenyl; R1-R2 are each independently selected from hydrogen, deuterium, C6-C30 aryl, C5-C30 N-heteroaryl, and the group consisting of.

2. The electron injection material compound according to claim 1, wherein, In formula (I), R1-R2 are each independently selected from hydrogen, deuterium, phenyl, naphthyl or pyridyl.

3. An electron injection material compound, characterized by, The electron injection material compound is selected from any one of the following chemical structures: 。 4. Use of the electron injection material compound according to any one of claims 1-3 in the preparation of an electronic device.

5. Use according to claim 4, characterized in that, The electronic device includes an organic photovoltaic device, an organic electroluminescent device, an organic integrated circuit, an organic field effect transistor, an organic light emitting transistor, an organic solar cell, an organic optical detector, an organic photoreceptor, an organic field quenching device, a light emitting electrochemical cell or an organic laser diode.

6. An organic electroluminescent device, characterized by The organic electroluminescent device includes a cathode, an anode and at least one organic functional layer between the two; the organic functional layer includes an electron injection layer, and the electron injection layer includes the electron injection material compound according to any one of claims 1-3.

7. The organic electroluminescent device according to claim 6, characterized in that The electron injection layer is further doped with a low work function metal material, and the low work function metal material is selected from one or more of silver, ytterbium and magnesium.

8. The organic electroluminescent device according to claim 7, characterized in that The doping amount of the low work function metal material in the electron injection layer is 1-5%.

9. The organic electroluminescent device according to claim 7, characterized in that, The low work function metal material is ytterbium, and the doping amount is 2%-2.5%.

10. The organic electroluminescent device according to claim 6, wherein The thickness of the electron injection layer is 50-150 A.

11. An organic optoelectronic device, characterized in that The organic optoelectronic device includes a substrate layer, a first electrode, a second electrode facing the first electrode, and an electron injection layer disposed between the first electrode and the second electrode; wherein the electron injection layer includes the electron injection material compound according to any one of claims 1-3.

12. A composition characterized in that, The composition includes the electron injection material compound according to any one of claims 1-3.

13. A formulation characterized in that, The preparation includes the electron injection material compound according to any one of claims 1-3 and at least one solvent.

14. A display or illumination device, characterized in that The device includes one or more of the organic electroluminescent devices according to claim 6.

Images