Organic compound having phosphine oxide structure, and organic electroluminescent device, display device, and lighting device comprising same

Abstract

The invention discloses an organic compound having a phosphine oxide structure, and an organic electroluminescent device, a display device and a lighting device comprising the same. The structural general formula of the organic compound is shown as a formula I. Phosphoric acid fragments are connected with nitrogen-containing aromatic rings of phenanthroline, the LUMO energy level of the material can be remarkably reduced through the synergistic effect of the electron withdrawing effect of phosphine oxide groups and the nitrogen-containing aromatic rings, two phenanthroline fragments with good coordination capacity are introduced on the phosphine oxide structure through aryl linking groups, the complexing condition of the material and an n-doped material is improved, and the material has good stability. The electron injection condition from the pCGL layer to the nCGL layer is improved, the charge generation capability is improved, the driving voltage of a device is reduced, in addition, phosphine oxide structures substituted on heteroaromatic rings at two end positions are V-shaped in a three-dimensional space, the molecular stacking effect is inhibited, the coordination combination of a material and a dopant is enhanced, and especially when the substitution site of phenanthroline is the ortho-position of a nitrogen atom, the material can be effectively prevented from being damaged. The film-forming property and stability of the material after being mixed with the n-doped material can be improved, and the service life of a device can be prolonged. And # imgabs0 # I is adopted.

Description

Technical Field

[0001] The present invention belongs to the technical field of OLED, and specifically comprises an organic compound with a phosphine oxide structure and an organic electroluminescent device, a display device and a lighting device comprising the same. Background Art

[0002] Organic light-emitting diode (OLED) displays have many advantages, such as high contrast, fast response, and flexibility. Therefore, technicians are constantly working on developing efficient OLED devices for mobile displays or long-life OLED devices for automotive applications.

[0003] Recently, the demand for higher brightness of OLED displays has been increasing, so the development of tandem OLEDs has attracted more and more attention, especially for the mid-sized display market. Tandem OLEDs consist of more than two single-layer OLEDs stacked with an intermediate layer called a charge generation layer (CGL) in the middle. The CGL layer usually consists of a stacked nCGL layer and a pCGL layer, which generate electrons and holes, respectively, and supply electrons to the stacked single-layer OLED on the anode side and holes to the stacked single-layer OLED on the cathode side. Tandem OLED displays have RGB emission layers independently stacked on sub-pixels of the same color, so current efficiency can be improved through the additional charges generated on the CGL.

[0004] Generally, the mechanism of charge generation is that the electrons on the HOMO of the pCGL layer jump to the LUMO energy level of the nCGL layer, so that a hole is generated on the pCGL layer and an electron is generated on the nCGL layer. At present, the common structural fragments of nCGL materials are nitrogen-containing heteroaryl groups, such as pyridine, quinoline, phenanthroline, etc., which use the electronegativity of nitrogen atoms in nitrogen-containing heteroaryl groups to improve the electron-withdrawing ability of the material. However, the LUMO of nCGL materials containing nitrogen heteroaromatic ring fragments is usually around -1.5eV, while the HOMO energy level of pCGL materials containing triarylamine fragments is usually around -5.0eV. Therefore, there is usually a large energy level difference between the nCGL layer and the pCGL layer. The excessive energy difference reduces the efficiency of charge generation, which makes the charge generation process more difficult.

[0005] In addition, the application scenarios of OLED display panels will become more and more extensive in the future, especially in car screens. Compared with portable mobile devices, the operating environment of car screens will be more severe, which requires OLED materials to have better stability under large temperature changes to ensure the stability of device performance. However, the large conjugated plane of the aromatic fragments commonly used in charge generation materials makes the materials easy to crystallize during the stable heating-cooling process in the environment, causing screen dead pixels. Therefore, it is urgent to develop new charge generation materials to better balance the energy level difference between the nCGL layer and the pCGL layer and improve the stability of the materials in harsh environments. Summary of the invention

[0006] In view of the above problems existing in the prior art, the present invention provides an organic compound having a phosphine oxide structure and an organic electroluminescent device, a display device and a lighting device comprising the same. The organic compound provided by the present invention can significantly reduce the LUMO energy level of the material, reduce the energy level difference between the nCGL layer and the pCGL layer, and improve the charge generation efficiency; the compound provided by the present invention has high stability and can better adapt to the temperature difference changes in harsh environments. Therefore, the organic compound provided by the present invention is suitable for the n-type charge generation layer of the tandem OLED device, which can solve the problems in the prior art.

[0007] To achieve the above objectives, the technical solutions adopted by the present invention include: The first aspect of the present invention provides an organic compound having a phosphine oxide structure, wherein the general structural formula of the organic compound is as shown in Formula I: I; Wherein, R1 is selected from one of the following structures: , , , , , ; Any hydrogen in R1 can be replaced by deuterium; L1 and L2 are each independently selected from substituted or unsubstituted C6 to C36 aryl groups. When L1 and L2 have substituents, the substituents are selected from phenyl or deuterium; R2 is selected from hydrogen or deuterium; In Formula I, at least one hydrogen may be substituted with deuterium, and at least one nitrogen may be substituted with nitrogen-15 (i.e. 15 N) substituted, at least one oxygen may be replaced by oxygen-17 (i.e. 17 O) or oxygen-18 (i.e. 18 O) substitution, at least one carbon may be substituted by carbon-13 (i.e. 13 C) Replacement.

[0008] Furthermore, the C6 to C36 aryl group is selected from one of the following structures: , , , , , , , .

[0009] Furthermore, the organic compound is selected from one of the following structures: , , , , , , , , , , , , , , , , , , , , , , , , ; Any hydrogen on the aromatic or heteroaromatic ring in the structure may be replaced by deuterium.

[0010] Furthermore, in Formula I, at least one hydrogen is replaced by deuterium.

[0011] Furthermore, the organic compound is selected from one of the following structures:

[0012]

[0013]

[0014] .

[0015] The second aspect of the present invention provides a use of the organic compound as described above in preparing an organic electroluminescent device.

[0016] The third aspect of the present invention provides an organic electroluminescent device, comprising an anode, a first hole transport region, a first light-emitting layer, a first electron transport region, a charge generation region, a second hole transport region, a second light-emitting layer, a second electron transport region, a cathode, and a covering layer, which are sequentially arranged on a substrate; wherein the charge generation region includes one or more organic compounds as described above.

[0017] Furthermore, the charge generation region includes an n-type charge generation layer and a p-type charge generation layer, wherein the n-type charge generation layer includes one or more organic compounds as described above.

[0018] A fourth aspect of the present invention provides a display device comprising the organic electroluminescent device as described above.

[0019] A fifth aspect of the present invention provides a lighting device, comprising the organic electroluminescent device as described above.

[0020] Beneficial effects of the present invention: The present invention uses a highly polarized phosphine oxide structure, which has a strong electron-withdrawing property, thereby improving the electron-withdrawing property of the aromatic structure connected to the structure. In particular, the present invention uses a phosphoric acid fragment to connect with the nitrogen-containing aromatic ring of phenanthroline, and the LUMO energy level of the material can be significantly reduced through the synergistic effect of the electron-withdrawing action of the phosphine oxide group and the nitrogen-containing aromatic ring. Furthermore, two phenanthroline fragments with good coordination ability are introduced into the phosphine oxide structure through an aromatic connecting group, which can improve the complexation with n-doped materials such as Li and Yb, improve the electron injection of the pCGL layer to the nCGL layer, and improve the charge generation ability. On the other hand, the phosphine oxide structure substituted on the two terminal heteroaromatic rings is V-shaped in three-dimensional space, which can inhibit the molecular stacking effect and enhance the coordination and combination of the molecule and the dopant through the V-shaped molecular configuration. In particular, when the substitution site of the phenanthroline is the ortho position of the nitrogen atom, the nitrogen atom can form a hydrogen bond with the hydrogen on the connected aromatic group, thereby improving the stability of the molecule itself, thereby improving the film forming property and stability of the material after mixing with the n-doped material. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of the organic electroluminescent device of the present invention. DETAILED DESCRIPTION

[0022] In order to more clearly understand the content of the present invention, it will be described in detail with reference to the drawings and embodiments.

[0023] The organic compound of the present invention is suitable for use in light-emitting elements, display panels and electronic devices, and is particularly suitable for use in organic electroluminescent devices. The electronic device of the present invention is a device comprising a layer of at least one organic compound, and the device may also comprise an inorganic material or a layer formed entirely of an inorganic material. The electronic device is preferably an organic electroluminescent device (OLED). The schematic structural diagram of an exemplary organic electroluminescent device is shown in FIG. Figure 1 shown.

[0024] Experimental Section In order to understand the content of the present invention more clearly, the luminescent characteristics of the organic compound, the preparation method of the organic compound and the device will be explained in detail in conjunction with the examples. Various chemical reactions can be applied to the synthetic method of the compound of one embodiment of the present invention. However, it should be noted that the synthetic method of the compound of one embodiment of the present invention is not limited to the synthetic method described below. Unless otherwise indicated, the subsequent synthesis is carried out in anhydrous solvent under a protective gas atmosphere. Solvents and reagents can be purchased from conventional reagent suppliers.

[0025] Synthesis Example In the structure of the present invention, if the substituents containing phenanthroline fragments on both sides of the phosphinoyl group are the same, the target product is obtained by one step of Suzuki coupling, and the chemical reaction equation is as follows:

[0026] If the substituents of the phenanthroline fragments on both sides of the phosphinoyl group are different, the target product can be obtained by two-step Suzuki coupling. The chemical reaction equation is as follows:

[0027] Synthesis Example 1

[0028] A1 (8.72 g, 20 mmol), B1 (15.48 g, 40 mmol) and potassium carbonate (8.2 g, 60 mmol) were added to a mixed solution of 300 ml toluene: water = 4:1 (V / V), and then tetrakistriphenylphosphine palladium (2.3 g, 2 mmol) was introduced under nitrogen protection. The reaction system was then heated to 110°C, refluxed and maintained for 8 hours, cooled to room temperature, quenched with water and separated, the organic phase was dried over anhydrous sodium sulfate, the solvent was removed by rotation, and the crude product was separated and purified by petroleum ether: dichloromethane = 1:1 (V / V) column. Finally, the product C1 was obtained: 12.59 g, yield: 79%, MS (m / z) (M+): 797.

[0029] Synthesis Example 2

[0030] The synthesis method is the same as that of Synthesis Example 1, except that A2 (4.36 g; 10 mmol) and B2 (3.82 g; 10 mmol) replace A1 and B1, and finally the product C2 is 6.14 g, with a yield of 78%, and MS (m / z) (M+): 787.

[0031] Synthesis Example 3

[0032] The synthesis method is the same as that of Synthesis Example 1, except that A3 (5.36 g; 10 mmol) and B3 (3.82 g; 10 mmol) replace A1 and B1, and finally the product C3 is 7.27 g, with a yield of 82%, and MS (m / z) (M+): 887.

[0033] Synthesis Example 4

[0034] The synthesis method is the same as that of Synthesis Example 1, except that A4 (5.36 g; 10 mmol) and B4 (3.82 g; 10 mmol) replace A1 and B1, and finally the product C4 is 7.27 g, with a yield of 82%, and MS (m / z) (M+): 887.

[0035] Synthesis Example 5

[0036] The synthesis method is the same as that of Synthesis Example 1, except that A5 (5.88 g; 10 mmol) and B5 (3.82 g; 10 mmol) replace A1 and B1, and finally the product C5 is obtained: 7.14 g, yield: 76%, MS (m / z) (M+): 939.

[0037] Synthesis Example 6

[0038] The synthesis method is the same as that of Synthesis Example 1, except that A6 (5.88 g; 10 mmol) and B6 (3.82 g; 10 mmol) replace A1 and B1, and finally the product C6 is obtained: 7.23 g, yield: 77%, MS (m / z) (M+): 939.

[0039] Synthesis Example 7

[0040] The synthesis method is the same as that of Synthesis Example 1, except that A7 (7.4 g; 10 mmol) and B7 (3.82 g; 10 mmol) replace A1 and B1, and finally the product C7 is 8.51 g, with a yield of 78%, and MS (m / z) (M+): 1091.

[0041] Synthesis Example 8

[0042] The synthesis method is the same as that of Synthesis Example 1, except that A8 (7.4 g; 10 mmol) and B8 (3.87 g; 10 mmol) replace A1 and B1, and finally the product C8 is 8.48 g, with a yield of 77%, and MS (m / z) (M+): 1101.

[0043] Synthesis Example 9

[0044] The synthesis method is the same as that of Synthesis Example 1, except that A9 (7.4 g; 10 mmol) and B9 (3.82 g; 10 mmol) replace A1 and B1, and finally the product C9 is 8.18 g, with a yield of 75%, and MS (m / z) (M+): 1091.

[0045] Synthesis Example 10

[0046] The synthesis method is the same as that of Synthesis Example 1, except that A10 (6.88 g; 10 mmol) and B10 (3.82 g; 10 mmol) replace A1 and B1, and finally the product C10 is 8.42 g, with a yield of 81%, and MS (m / z) (M+): 1039.

[0047] Synthesis Example 11

[0048] The synthesis method is the same as that of Synthesis Example 1, except that A11 (6.88 g; 10 mmol) and B11 (3.82 g; 10 mmol) replace A1 and B1, and finally the product C11: 8.21 g, yield: 79%, MS (m / z) (M+): 1039.

[0049] Synthesis Example 12

[0050] The synthesis method is the same as that of Synthesis Example 1, except that A12 (7.4 g; 10 mmol) and B12 (3.82 g; 10 mmol) replace A1 and B1, and finally the product C12 is obtained: 9.38 g, yield: 86%, MS (m / z) (M+): 1091.

[0051] Synthesis Example 13

[0052] The synthesis method is the same as that of Synthesis Example 1, except that A13 (4.36 g; 10 mmol) and B13 (3.06 g; 10 mmol) replace A1 and B1, and finally the product C13: 5.4 g, yield: 85%, MS (m / z) (M+): 635.

[0053] Synthesis Example 14

[0054] The synthesis method is the same as that of Synthesis Example 1, except that A14 (4.36 g; 10 mmol) and B14 (3.06 g; 10 mmol) replace A1 and B1, and finally the product C14 is obtained: 5.4 g, yield: 85%, MS (m / z) (M+): 635.

[0055] Synthesis Example 15

[0056] The synthesis method is the same as that of Synthesis Example 1, except that A15 (4.36 g; 10 mmol) and B15 (3.06 g; 10 mmol) replace A1 and B1, and finally the product C15 is obtained: 5.27 g, yield: 83%, MS (m / z) (M+): 635.

[0057] Synthesis Example 16

[0058] The synthesis method is the same as that of Synthesis Example 1, except that A16 (5.36 g; 10 mmol) and B16 (3.06 g; 10 mmol) replace A1 and B1, and finally the product C16 is obtained: 5.59 g, yield: 76%, MS (m / z) (M+): 735.

[0059] Synthesis Example 17

[0060] The synthesis method is the same as that of Synthesis Example 1, except that A17 (5.36 g; 10 mmol) and B17 (3.06 g; 10 mmol) replace A1 and B1, and finally the product C17 is obtained: 6.25 g, yield: 85%, MS (m / z) (M+): 735.

[0061] Synthesis Example 18

[0062] The synthesis method is the same as that of Synthesis Example 1, except that A18 (6.88 g; 10 mmol) and B18 (3.06 g; 10 mmol) replace A1 and B1, and finally the product C18 is 6.83 g, with a yield of 77%, and MS (m / z) (M+): 887.

[0063] Synthesis Example 19

[0064] The synthesis method is the same as that of Synthesis Example 1, except that A19 (4.36 g; 10 mmol) and B19 (3.82 g; 10 mmol) replace A1 and B1, and finally the product C19 is obtained: 5.9 g, yield: 75%, MS (m / z) (M+): 787.

[0065] Synthesis Example 20

[0066] The synthesis method is the same as that of Synthesis Example 1, except that A20 (5.36 g; 10 mmol) and B20 (3.87 g; 10 mmol) replace A1 and B1, and finally the product C20 is obtained: 7.36 g, yield: 82%, MS (m / z) (M+): 897.

[0067] Synthesis Example 21

[0068] The synthesis method is the same as that of Synthesis Example 1, except that A21 (5.88 g; 10 mmol) and B21 (3.82 g; 10 mmol) replace A1 and B1, and finally the product C21: 7.32 g, yield: 78%, MS (m / z) (M+): 939.

[0069] Comparative Examples 1-3 The following provides compounds D1-D3 that were tested during the research process, and their specific structural formulas are as follows: D1. D2, D3.

[0070] Material performance evaluation In order to further illustrate the technical advantages brought by the present invention, the LUMO energy level and Tg of the compounds provided in the embodiments of the present invention are tested and characterized to illustrate that the compounds provided by the present invention have unique advantages: The LUMO energy level values ​​of compounds C1 to C21 provided by the present invention and compounds D1 to D3 provided by the comparative examples were calculated using the ORCA software using the B3LYP / 6-31G(d) method. The glass transition temperatures Tg of compounds C1 to C21 provided by the present invention and compounds D1 to D3 provided by the comparative examples were determined by differential scanning calorimetry (DSC, DSC204F1 differential scanning calorimeter manufactured by NETZSCH, Germany) at a heating rate of 10°C / min. The results are shown in Table 1.

[0071] Table 1

[0072] It can be seen from the above results that the compounds provided by the present invention have a deeper LUMO energy level and a higher Tg. Since the compounds provided by the present invention are substituted with an aromatic group on the nitrogen-containing heteroaromatic ring of phenanthroline, it is beneficial to give full play to the electron-pulling effect of the nitrogen atom and cooperate with the electron-pulling effect of the phosphine oxygen group, so that the compounds provided by the present invention have a deeper LUMO energy level, thereby reducing the energy level difference between pCGL and nCGL and improving the charge generation efficiency. In particular, in some embodiments of the present invention, the nitrogen atom of phenanthroline can form an intramolecular hydrogen bond with the hydrogen on the ortho-connected aromatic group, thereby improving the stability of the molecule itself. Further, the connecting groups of the compounds provided by the present invention are all substituted on the nitrogen-containing heteroaromatic ring, so that the molecular structure extends along the long axis direction of phenanthroline, which is beneficial to the interaction between molecules when the molecules are disorderly stacked, thereby improving the Tg of the material, so the compounds provided by the present invention are easier to form a uniform and dense film, thereby helping to improve the life of the device.

[0073] On the one hand, the compounds of Comparative Examples 1 and 2 are substituted on the aromatic ring of phenanthroline, and there is no aromatic substituent at the ortho position of the nitrogen atom on the nitrogen-containing ring, while the present invention uses aromatic substitution on the nitrogen-containing heteroaromatic ring of phenanthroline, which is conducive to the full play of the electron-withdrawing effect of the nitrogen atom and the electron-withdrawing effect of the phosphine oxygen group. Therefore, compared with the compounds of Comparative Examples 1 and 2, the LUMO energy level of the compounds provided by the present invention is deeper; on the other hand, the compounds of Comparative Examples 1 and 2 cannot form intramolecular hydrogen bonds, and the molecular stability is poor, while in some embodiments of the present invention, the ortho position of the nitrogen atom of phenanthroline contains an aromatic substituent, and the intramolecular hydrogen bonds formed can improve the stability of the molecule. The connecting groups of the invention are all substituted on the nitrogen-containing ring, so that the molecular structure extends along the long axis direction of phenanthroline, which is beneficial to the interaction between molecules when the molecules are disorderly stacked. Therefore, compared with the compounds of Comparative Examples 1 and 2, the Tg of the compound provided by the present invention is higher; although Comparative Example 3 also uses the same compound substituted on the nitrogen-containing aromatic ring, the phosphine oxygen structure substituted on the two terminal heteroaromatic rings of the compound provided by the present invention is V-shaped in three-dimensional space, which inhibits the molecular stacking effect, and can also enhance the coordination and binding between the molecule and the dopant through the V-shaped molecular configuration, further enhancing the stability of the molecule itself. Therefore, compared with the compound of Comparative Example 3, the Tg of the compound provided by the present invention is higher.

[0074] Fabrication and characterization of OLEDs Device Embodiment The organic electroluminescent device provided by the present invention comprises an anode, a first hole transport region, a first light-emitting layer, a first electron transport region, a charge generation region, a second hole transport region, a second light-emitting layer, a second electron transport region, a cathode, and a covering layer which are sequentially arranged on a substrate; Further, the first hole transport region includes a hole injection layer, a first hole transport layer and a first electron blocking layer; the first electron transport region includes a first hole blocking layer and a first electron transport layer; the charge generation region includes an n-type charge generation layer and a p-type charge generation layer; the second hole transport region includes a second hole transport layer and a second electron blocking layer; the second electron transport region includes a second hole blocking layer, a second electron transport layer and an electron injection layer.

[0075] Furthermore, the light-emitting layer is composed of a main material and a doping material, and the main material of the light-emitting layer can be composed of one molecular material or multiple molecular materials.

[0076] The deuterated organic compound of the present invention can be used in one or more layers of the above-mentioned organic electroluminescent device, preferably used as the n-type charge generation layer material of the device.

[0077] The anode in the embodiment adopts anode materials commonly used in the art, such as ITO, Ag or their multilayer structures. The hole injection layer adopts hole injection materials commonly used in the art, and F4TCNQ, HATCN, NDP-9, etc. are added for doping. The hole transport layer adopts hole transport materials commonly used in the art. The light-emitting layer adopts light-emitting materials and doping materials commonly used in the art, for example, it can be composed of a main material and a doping material. The electron transport layer adopts electron transport materials commonly used in the art. The electron injection layer adopts electron injection materials commonly used in the art, such as LiQ, LiF, Yb, etc. The n-type charge generation layer material adopts the deuterated organic compound provided by the present invention. The cathode adopts materials commonly used in the art, such as metal Al, Ag or metal mixtures (Ag-doped Mg, Ag-doped Ca, etc.).

[0078] The electrode preparation method and the deposition method of each functional layer in this embodiment are conventional methods in the art, such as vacuum thermal evaporation or inkjet printing, etc., which will not be described in detail here. Only some process details and test methods in the preparation process are supplemented as follows: Device Example 1 The substrates used in the present invention were subjected to the following operations: the ITO substrate was patterned so that its luminous area had a size of 3 mm×3 mm, and then ultrasonically treated with water / isopropanol, UV / ozone irradiation, and then dried at 100°C. After that, the ITO substrate was mounted on a substrate holder of a vacuum deposition device and the pressure was adjusted so that the vacuum rate became 1×10 -7 torr.

[0079] Subsequently, on the ITO layer (anode) formed on the substrate, compound HT01 and compound PD01 (the mass ratio of HT01 to PD01 is 97:3) are vacuum deposited with a thickness of 10 nm to form a hole injection layer; secondly, on the hole injection layer, compound HT01 is vacuum deposited with a thickness of 20 nm to form a first hole transport layer, and secondly, on the first hole transport layer, compound BP01 is vacuum deposited with a thickness of 5 nm to form a first electron blocking layer, and secondly, on the first electron blocking layer, a mixture of compound BH01 and compound BD01 is vacuum deposited with a thickness of 20 nm to form a first light-emitting layer, wherein BH01 is used as The main body and BD01 are dopants, and the mass ratio of the main body to the dopant is 98:2; then, on the above-mentioned first light-emitting layer, the compound HB01 is vacuum deposited with a thickness of 5nm to form a first hole blocking layer; then, on the above-mentioned first hole blocking layer, the compound ET01 and the compound LiQ (the mass ratio of ET01 to LiQ is 1:1) are vacuum deposited with a thickness of 15nm to form a first electron transport layer; then, on the above-mentioned first electron transport layer, the compound C1 and Yb (the mass ratio of C1 to Yb is 98:2) are vacuum deposited with a thickness of 15nm to form an n-type charge generation layer, and the compound HT01 and the compound P are vacuum deposited with a thickness of 10nm. D01 (the mass ratio of HT01 to PD01 is 97:3) to form a p-type charge generation layer, and then on the p-type charge generation layer, the compound HT01 is vacuum deposited with a thickness of 20nm to form a second hole transport layer, and then on the second hole transport layer, the compound BP01 is vacuum deposited with a thickness of 5nm to form a second electron blocking layer, and then on the second electron blocking layer, a mixture of the compound BH01 and the compound BD01 is vacuum deposited with a thickness of 20nm to form a second light-emitting layer, wherein BH01 is used as a host and BD01 is used as a dopant, and the mass ratio of the host to the dopant is 98:2; then on the second light-emitting layer On the above-mentioned second hole blocking layer, compound HB01 is vacuum deposited with a thickness of 5 nm to form a second hole blocking layer; then on the above-mentioned second hole blocking layer, compound ET01 and compound LiQ (the mass ratio of ET01 to LiQ is 1:1) are vacuum deposited with a thickness of 15 nm to form a second electron transport layer; then on the above-mentioned second electron transport layer, Yb is deposited with a thickness of 1 nm to form an electron injection layer, and then on the above-mentioned electron injection layer, Mg and Ag (the mass ratio of Mg and Ag is 1:9) are deposited with a thickness of 15 nm to form a cathode, and then on the above-mentioned cathode, CP01 is deposited with a thickness of 50 nm to form a covering layer, and a stacked organic electroluminescent device is prepared.

[0080] In addition to the materials used in the present invention, the molecular structures of the remaining materials in each layer of the device are as follows:

[0081]

[0082] Device Example 2-21 The above method is used to prepare the compound described in the example into an organic electroluminescent device, wherein C2 to C21 are used to replace C1 to prepare organic electroluminescent device examples 2-21.

[0083] Device Comparison Examples 1-3 The above method was used to prepare the compounds described in the examples into organic electroluminescent devices, wherein D1 to D3 were used to replace C1 to prepare organic electroluminescent device comparative examples 1-3.

[0084] The OLED devices described above were tested by standard methods. For this purpose, at J = 10 mA / cm 2 The driving voltage and luminous efficiency of the organic electroluminescent device are determined at a current density of J = 20 mA / cm 2 When working under LT95, the luminous brightness drops to 95% of its initial value L0 after time LT95.

[0085] The test instruments and methods for testing the performance of the OLED devices in the above embodiments and comparative examples are as follows: The luminous efficiency CE (cd / A) and color coordinates (CIEy) were tested using a spectrum scanner PhotoResearch PR-635; Current density and lighting voltage: tested using a digital source meter Keithley 2400; The luminous efficiency of blue light devices is greatly affected by chromaticity. The industry generally uses BI value as the basis for the efficiency of blue light devices. BI (Blue index) is obtained by dividing the luminous efficiency CE (cd / A) by the color coordinate (CIEy); Life test: Use silicon photoelectric OLED device life test system.

[0086] The performance test results of the above devices are listed in Table 2.

[0087] Table 2 Device performance test results

[0088] As can be seen from the above table, compared with the comparative example, the organic electroluminescent device provided by the present invention has a lower driving voltage and a longer lifespan. The compounds of comparative examples 1 and 2 are substituted on the aromatic ring of phenanthroline, and there is no aromatic structure at the ortho position of the nitrogen atom on the nitrogen-containing ring. The present invention introduces a connecting group on the nitrogen-containing ring of phenanthroline, and connects two phenanthrolines containing connecting groups on the nitrogen-containing aromatic rings through the phosphine oxygen structure to form a molecule, giving full play to the role of the phosphine oxygen group and the nitrogen-containing ring in regulating the energy level, reducing the energy level difference between pCGL and nCGL, and reducing the potential barrier for charge generation. Therefore, compared with comparative examples 1 and 2, the organic electroluminescent device provided by the present invention has a lower driving voltage; in some embodiments of the present invention, the ortho position of the nitrogen atom of phenanthroline contains an aromatic substituent, and the hydrogen bond formed can improve the stability of the molecule. The connecting groups of the present invention are all substituted on the nitrogen-containing ring, so that the molecular structure extends along the long axis direction of the phenanthroline, which is beneficial to the interaction between molecules when the molecules are disorderly stacked. The compounds of comparative examples 1 and 2 are used to make their Tg higher, while the compounds of comparative examples 1 and 2 cannot form intramolecular hydrogen bonds and have poor molecular stability. Therefore, the organic electroluminescent device provided by the present invention has a longer life than that of comparative examples 1 and 2. Although the compound of comparative example 3 also adopts the same substitution on the nitrogen-containing aromatic ring, the phosphine oxygen structure substituted on the two terminal heteroaromatic rings of the compound provided by the present invention is V-shaped in three-dimensional space, which suppresses the molecular stacking effect and can enhance the coordination and binding between the molecule and the dopant through the V-shaped molecular configuration. In particular, when the substitution site of phenanthroline is the ortho position of the nitrogen atom, the nitrogen atom can form a hydrogen bond with the hydrogen connected to the aromatic group, thereby improving the stability of the molecule itself, thereby improving the film-forming property and stability of the material after mixing with the dopant. Therefore, compared with comparative example 3, the organic electroluminescent device provided by the present invention has obvious improvements in voltage and life.

[0089] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. An organic compound having a phosphine oxide structure, characterized in that: The general structural formula of the organic compound is shown in Formula I: I； Wherein, R1 is selected from one of the following structures: 、 、 、 、 、 ； Any hydrogen in R1 can be replaced by deuterium; L1 and L2 are each independently selected from substituted or unsubstituted C6 to C36 aryl groups. When L1 and L2 have substituents, the substituents are selected from phenyl or deuterium; R2 is selected from hydrogen or deuterium; In Formula I, at least one hydrogen may be substituted with deuterium, at least one nitrogen may be substituted with nitrogen-15, at least one oxygen may be substituted with oxygen-17 or oxygen-18, and at least one carbon may be substituted with carbon-13.

2. The organic compound according to claim 1, characterized in that The substituted or unsubstituted C6 to C36 aryl group is selected from one of the following structures: 、 、 、 、 、 、 、 。 3. The organic compound according to claim 1, characterized in that The organic compound is selected from one of the following structures: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 ； Any hydrogen on the aromatic or heteroaromatic ring in the structure may be replaced by deuterium.

4. The organic compound according to claim 1, characterized in that In Formula I, at least one hydrogen is replaced by deuterium.

5. The organic compound according to claim 1, characterized in that The organic compound is selected from one of the following structures: 。 6. Use of the organic compound according to any one of claims 1 to 5 in the preparation of an organic electroluminescent device.

7. An organic electroluminescent device, characterized in that: It includes an anode, a first hole transport region, a first light-emitting layer, a first electron transport region, a charge generation region, a second hole transport region, a second light-emitting layer, a second electron transport region, a cathode, and a covering layer, which are sequentially arranged on a substrate; wherein the charge generation region includes one or more organic compounds as described in any one of claims 1 to 5.

8. The organic electroluminescent device according to claim 7, characterized in that: The charge generation region comprises an n-type charge generation layer and a p-type charge generation layer, wherein the n-type charge generation layer comprises one or more organic compounds according to any one of claims 1 to 5.

9. A display device, characterized in that Comprising the organic electroluminescent device as claimed in claim 7 or 8.

10. A lighting device, characterized in that Comprising the organic electroluminescent device as claimed in claim 7 or 8.

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