Phosphine oxide group-containing polybipyridine compound, and organic electroluminescent device, display device and lighting device comprising same

Abstract

The invention discloses a phosphine oxide group-containing polypyridine compound, and an organic electroluminescent device, a display device and a lighting device comprising the same. The structural general formula of the multi-bipyridine compound is as shown in formula I in the specification. According to the polypyridine compound provided by the invention, by introducing a polypyridine group, a certain coordination complexing site is provided, the coordination complexing ability with an nCGL material is improved, and by introducing a phenylphosphine oxide group, conjugation is blocked, the molecular weight is increased, and the energy gap and the stability of the material are increased; particularly, a pyridine / quinoxaline fragment is used for connecting a phosphine oxide group and a polypyridyl group, the driving voltage of the laminated device can be further reduced, in addition, complexing sites can be increased by selecting a proper connecting position, for example, when pyridine is used as a connecting group and the connecting position of the pyridine and the polypyridyl group is at the ortho-position of an N atom on a pyridine structure, the complexing sites can be increased, and the complexing sites can be increased. The performance of a device prepared from the material is better. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the technical field of OLED, and specifically comprises a polypyridine compound containing a phosphine oxygen group and an organic electroluminescent device, a display device and a lighting device containing the same. Background Art

[0002] Organic light-emitting diodes (OLEDs) have significant advantages in display effects, performance, application forms and environmental protection due to their self-luminous characteristics. Each pixel can control light independently, achieving infinite contrast and deep black. With wide color gamut and high resolution, they can present delicate and realistic images. They also have extremely fast response speed, low power consumption, and thin and light structure, which is easy to integrate and can support special scenes such as transparent display. Therefore, they are becoming the benchmark for the next generation of display technology.

[0003] In organic light-emitting diode (OLED) devices, performance optimization of n-type charge generation layer (nCGL) materials is one of the key challenges to improve device efficiency and stability. At present, nCGL materials have the following three major technical bottlenecks: 1) Insufficient coordination stability and energy level regulation efficiency: N-type charge generation layer materials usually need to be complexed with dopants to adjust the energy level and reduce the energy level difference. This requires that the charge generation material contains a coordination group in its molecular structure. Nitrogen-containing aromatic groups usually have coordination ability, such as pyridine, but the coordination compound formed by a single coordination group and the dopant material has poor stability, while the coordination complexation of the chelated ligand composed of multiple coordination sites and the dopant is more stable. Common nCGL materials have only one chelating center. Since the N-type dopant and the N-type charge generation material gradually form a complex during the film formation process, the coordination process may be insufficient due to the small number of chelating sites or the excessive steric hindrance of the chelating group, which reduces the role of the N-type dopant material in regulating the energy level and makes it difficult to reduce the voltage; 2) Interface charge loss and material degradation problems: The charge transfer at the interface between nCGL and pCGL depends on the electron transfer from the HOMO energy level of pCGL to the LUMO energy level of nCGL. However, it is difficult to achieve a sufficiently small energy level difference through molecular design of existing organic small molecules, and doping regulation is required. However, there are uncoordinated nCGL molecules in the actual film layer, and their unregulated HOMO energy level may cause the holes of pCGL to be directly injected into the HOMO of nCGL, causing interfacial charge recombination, accelerating the degradation of nCGL materials, and losing electrons on LUMO, significantly reducing the charge generation efficiency. Therefore, the HOMO energy level depth of nCGL needs to be further optimized to suppress such losses; 3) The contradiction between the design of multifunctional groups and coordination ability: Although the electron-pulling fragments in electron transport materials such as triazine, pyrimidine, pyridine and other nitrogen-containing heterocycles have good ability to improve the electron transport of materials, they are usually unable to form a chelate structure with the metal when used alone, and thus rarely appear in the charge generation layer. However, when the above fragments are used in combination, they may have certain coordination ability and can be used as fragments of the charge generation layer. Although there are reports on the design of directly connecting terpyridine and phosphoric acid, there are multiple connecting groups between the phosphine oxygen group and the nitrogen-containing heterocycle. The influence of the chemical structure and connection position of different connecting groups on the material performance is still unclear and still needs further study.

[0004] 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 to improve the comprehensive performance of the materials. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention provides a polypyridine compound containing a phosphine oxygen group and an organic electroluminescent device, a display device and a lighting device containing the same.

[0006] To achieve the above objectives, the technical solutions adopted by the present invention include:

[0007] The first aspect of the present invention provides a polypyridine compound containing a phosphine oxide group, wherein the general structural formula of the polypyridine compound is as shown in Formula I:

[0008]

[0009] Wherein, X represents C or N;

[0010] L represents a substituted or unsubstituted C5 to C20 nitrogen-containing aromatic ring;

[0011] When L has a substituent, the substituent is selected from phenyl or deuterium;

[0012] In formula I, any hydrogen may be replaced by deuterium, any nitrogen may be replaced by nitrogen-15, any oxygen may be replaced by oxygen-17 or oxygen-18, and any carbon may be replaced by carbon-13.

[0013] Further, L represents a substituted or unsubstituted C5 to C15 nitrogen-containing aromatic ring.

[0014] Further, L represents a substituted or unsubstituted C5 to C10 nitrogen-containing aromatic ring.

[0015] Further, the X represents N;

[0016] The L represents one of substituted or unsubstituted pyridine, substituted or unsubstituted quinazoline, and substituted or unsubstituted quinoxaline.

[0017] Further, the L represents

[0018] One of them.

[0019] Further, the L represents

[0020] One of them.

[0021] When L is selected from pyridine, for example Etc., a more preferred way of connecting terpyridine (or dipyridine) and the phosphorus oxygen structure is that terpyridine (or dipyridine) is connected to the N-ortho position on pyridine, and the position of the other connecting position is selected arbitrarily, and it is connected to the phosphorus oxygen structure.

[0022] When L is selected from a pyridine structure, for example Etc., a more preferred way to connect terpyridine (or dipyridine) and the phosphorus oxygen structure is: only focus on the connection position on the pyridine structure, and the terpyridine (or dipyridine) can be connected to the N-ortho position on the pyridine structure.

[0023] Furthermore, the polypyridine compound is selected from one of the structures shown below:

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033] The second aspect of the present invention provides a use of the polypyridine compound described above in preparing an organic electroluminescent device.

[0034] 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 of the polypyridine compounds as described above.

[0035] 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.

[0036] A fourth aspect of the present invention provides a display device comprising the organic electroluminescent device as described above.

[0037] A fifth aspect of the present invention provides a lighting device, comprising the organic electroluminescent device as described above.

[0038] Beneficial effects of the present invention:

[0039] The polypyridine compound provided by the present invention has phosphine oxide group and polypyridine group as main constituent fragments. On the one hand, the polypyridine group can provide certain coordination and complexing sites to improve the coordination and complexing ability with the nCGL material. On the other hand, the phenylphosphine oxide group can block conjugation, increase the molecular weight, and increase the energy gap and stability of the material. In particular, the researchers of the present invention found that when pyridine / quinoxaline fragments are used as connecting groups, the prepared materials can be applied to the charge generation layer to further reduce the driving voltage of the stacked device compared with triazine, pyrimidine, oxathiophene, etc. as connecting groups. This may be because when pyridine / quinoxaline is used as a connecting group, the electron pulling ability of pyridine and quinoxaline is relatively small, and the effect on the material energy level is small. In addition, certain substitution positions can increase the complexing sites. For example, when pyridine is used as a connecting group and the position connected to the polypyridine group is at the ortho position of N on the pyridine structure, the device prepared using the material of the present invention has better performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic structural diagram of the organic electroluminescent device of the present invention. DETAILED DESCRIPTION

[0041] 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.

[0042] 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.

[0043] Experimental Section

[0044] 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.

[0045] Synthesis Example

[0046] In the structure of the present invention, if the substituents 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:

[0047]

[0048] In the above general formula, L is a single bond or a phenyl group, and "ring N" represents a nitrogen-containing heterocyclic ring, which in the present invention mainly refers to pyridine, quinoxaline or quinazoline.

[0049] For example, the preparation of A6 is as follows:

[0050]

[0051] Under nitrogen protection, C1 (3.60 g; 10 mmol), D1 (4.04 g; 20 mmol), [Ru(bpy) 3 Cl 2 ]·6H 2 O (0.75 g; 1 mmol), [Ni(cod) 2 ] (0.11g; 0.4mmol), dtbbpy (0.11g; 0.4mmol), Cs 2 CO 3 (6.52 g; 20 mmol) and anhydrous methanol (100 mL). Afterwards, the solution was placed about 5 cm away from a 3W blue LED and stirred at room temperature for 24 hours. Then, the solvent was removed in vacuo, and the crude product was purified by silica gel flash chromatography (eluent: petroleum ether / ethyl acetate = 1: 1, v / v) to obtain a pure product A6 (3.91 g, 9 mmol) as a white solid in a yield of 90%, MS (m / z) (M+): 434.

[0052] The synthesis methods of other type A intermediates are similar to the preparation method of A6.

[0053] Synthesis Example 1

[0054]

[0055] Under nitrogen protection, A1 (3.58 g; 10 mmol), B1 (3.59 g; 10 mmol), potassium carbonate (4.14 g, 30 mmol), tetrakis(triphenylphosphine)palladium (0.12 g, 0.1 mmol) were added to the reaction bottle, and 80 mL of deoxygenated solvent tetrahydrofuran and 20 mL of water were added, and the reaction was carried out at 60°C for 12 h. After the reaction was completed, the reaction system was cooled to room temperature, 60 mL of water was added, stirred for 5 min, and then separated. The organic phase was washed with 120 mL of water again and separated, and the organic phase was repeated twice. The solvent was removed from the organic phase using a rotary evaporator, and the obtained solid was recrystallized and purified using toluene to finally obtain the product C1: 4.19 g, yield: 82%, MS (m / z) (M+): 511.

[0056] Synthesis Example 2

[0057]

[0058] The method is the same as that of Synthesis Example 1, except that A2 (3.58 g; 10 mmol) and B2 (3.69 g; 10 mmol) replace A1 and B1, and finally the product C2 is 4.48 g, with a yield of 86%, and MS (m / z) (M+): 521.

[0059] Synthesis Example 3

[0060]

[0061] The method is the same as that of Synthesis Example 1, except that A3 (3.58 g; 10 mmol) and B3 (3.59 g; 10 mmol) replace A1 and B1, and finally the product C3: 4.09 g, yield: 80%, MS (m / z) (M+): 511.

[0062] Synthesis Example 4

[0063]

[0064] The method is the same as that of Synthesis Example 1, except that A4 (4.34 g; 10 mmol) and B4 (3.59 g; 10 mmol) replace A1 and B1, and finally the product C4: 4.55 g, yield: 89%, MS (m / z) (M+): 511.

[0065] Synthesis Example 5

[0066]

[0067] The method is the same as that of Synthesis Example 1, except that A5 (4.34 g; 10 mmol) and B5 (3.59 g; 10 mmol) replace A1 and B1, and finally product C5: 4.75 g, yield: 81%, MS (m / z) (M+): 587.

[0068] Synthesis Example 6

[0069]

[0070] The method is the same as that of Synthesis Example 1, except that A6 (4.34 g; 10 mmol) and B6 (3.59 g; 10 mmol) replace A1 and B1, and finally the product C6 is obtained: 5.17 g, yield: 88%, MS (m / z) (M+): 587.

[0071] Synthesis Example 7

[0072]

[0073] The method is the same as that of Synthesis Example 1, except that A7 (4.34 g; 10 mmol) and B7 (3.59 g; 10 mmol) replace A1 and B1, and finally the product C7 is 5.11 g, with a yield of 87%, and MS (m / z) (M+): 587.

[0074] Synthesis Example 8

[0075]

[0076] The method is the same as that of Synthesis Example 1, except that A8 (4.34 g; 10 mmol) and B8 (3.59 g; 10 mmol) replace A1 and B1, and finally the product C8 is 5.28 g, with a yield of 90%, and MS (m / z) (M+): 587.

[0077] Synthesis Example 9

[0078]

[0079] The method is the same as that of Synthesis Example 1, except that A9 (3.58 g; 10 mmol) and B9 (3.59 g; 10 mmol) replace A1 and B1, and finally product C9: 4.09 g, yield: 80%, MS (m / z) (M+): 511.

[0080] Synthesis Example 10

[0081]

[0082] The method is the same as that of Synthesis Example 1, except that A10 (3.58 g; 10 mmol) and B10 (3.59 g; 10 mmol) are used to replace A1 and B1, and finally product C10: 4.39 g, yield: 86%, MS (m / z) (M+): 511.

[0083] Synthesis Example 11

[0084]

[0085] The method is the same as that of Synthesis Example 1, except that A11 (3.58 g; 10 mmol) and B11 (3.59 g; 10 mmol) are used to replace A1 and B1, and finally product C11: 4.45 g, yield: 87%, MS (m / z) (M+): 511.

[0086] Synthesis Example 12

[0087]

[0088] The method is the same as that of Synthesis Example 1, except that A12 (3.58 g; 10 mmol) and B12 (3.59 g; 10 mmol) replace A1 and B1, and finally the product C12: 4.34 g, yield: 85%, MS (m / z) (M+): 511.

[0089] Synthesis Example 13

[0090]

[0091] The method is the same as that of Synthesis Example 1, except that A13 (4.34 g; 10 mmol) and B13 (3.59 g; 10 mmol) replace A1 and B1, and finally the product C13: 5.28 g, yield: 90%, MS (m / z) (M+): 587.

[0092] Synthesis Example 14

[0093]

[0094] The method is the same as that of Synthesis Example 1, except that A14 (4.34 g; 10 mmol) and B14 (3.59 g; 10 mmol) replace A1 and B1, and finally the product C14: 4.7 g, yield: 80%, MS (m / z) (M+): 587.

[0095] Synthesis Example 15

[0096]

[0097] The method is the same as that of Synthesis Example 1, except that A15 (4.34 g; 10 mmol) and B15 (3.59 g; 10 mmol) replace A1 and B1, and finally the product C15: 4.81 g, yield: 82%, MS (m / z) (M+): 587.

[0098] Synthesis Example 16

[0099]

[0100] The method is the same as that of Synthesis Example 1, except that A16 (4.34 g; 10 mmol) and B16 (3.59 g; 10 mmol) replace A1 and B1, and finally the product C16 is obtained: 4.87 g, yield: 83%, MS (m / z) (M+): 587.

[0101] Synthesis Example 17

[0102]

[0103] The method is the same as that of Synthesis Example 1, except that A17 (4.09 g; 10 mmol) and B17 (3.59 g; 10 mmol) replace A1 and B1, and finally the product C17: 4.5 g (yield: 80%), MS (m / z) (M+): 562.

[0104] Synthesis Example 18

[0105]

[0106] The method is the same as that of Synthesis Example 1, except that A18 (4.85 g; 10 mmol) and B18 (3.59 g; 10 mmol) replace A1 and B1, and finally the product C18 is 5.55 g, with a yield of 87%, and MS (m / z) (M+): 638.

[0107] Synthesis Example 19

[0108]

[0109] The method is the same as that of Synthesis Example 1, except that A19 (4.34 g; 10 mmol) and B19 (3.61 g; 10 mmol) replace A1 and B1, and finally the product C19: 5.3 g, yield: 90%, MS (m / z) (M+): 589.

[0110] Synthesis Example 20

[0111]

[0112] The method is the same as that of Synthesis Example 1, except that A20 (4.34 g; 10 mmol) and B20 (3.61 g; 10 mmol) replace A1 and B1, and finally the product C20 is obtained: 5.07 g, yield: 86%, MS (m / z) (M+): 589.

[0113] Synthesis Example 21

[0114]

[0115] The method is the same as that of Synthesis Example 1, except that A21 (4.85 g; 10 mmol) and B21 (3.58 g; 10 mmol) replace A1 and B1, and finally the product C21: 5.16 g, yield: 81%, MS (m / z) (M+): 637.

[0116] Comparative Examples 1-7

[0117] The compounds DB01-DB07 that were tested during the research are provided below, and their specific structural formulas are as follows:

[0118]

[0119] Material performance evaluation

[0120] The technical effect achieved by the material of the present invention is the comprehensive result of the reasonable design and regulation of the advantageous performance of each fragment of the molecular structure. The reasons are multifaceted, but in order to further illustrate the technical advantages brought by the present invention, the complexing sites and HOMO energy levels of the synthetic examples of the present invention are tested and characterized to illustrate the unique advantages of the material of the present invention.

[0121] The complexation sites are mainly located on the polypyridine groups, M is a metal atom, and the common complexation modes are as follows:

[0122]

[0123] Complexation site: According to the compound structure of the synthesis example and the comparative example, the number of complexation sites is counted. The more complexation sites there are, the greater the possibility of complexation with the metal, and the more stable the complex is, which is beneficial to reduce the electron injection barrier and improve the charge generation capacity. HOMO energy level evaluation method: The material is identified by testing the redox characteristics of the material using cyclic voltammetry (CV); the specific steps are: the sample is dissolved in ultra-dry dichloromethane with a concentration of 0.5 mg / mL, the electrolyte is an organic solution of 0.1 M tetrabutylammonium hexafluorophosphate, and the electrolyte is 0.1 M Bu 4 NPF 6 , the electrodes were a three-electrode system (working electrode: GC, reference electrode: Ag / AgCl, counter electrode: Pt), the potential (V)-current (A) diagram of each compound was obtained, and the HOMO energy level of each material was calculated from the oxidation starting point of the diagram.

[0124] Table 1 shows the relevant data on complexation sites and HOMO energy levels of the compounds of the synthesis examples and comparative examples.

[0125] Table 1

[0126] Material Number of complexation sites HOMO C1 5 -5.98 C2 5 -5.98 C3 5 -5.97 C4 5 -5.96 C5 5 -5.96 C6 5 -5.99 C7 5 -5.98 C8 5 -5.96 C9 3 -5.91 C10 3 -5.92 C11 3 -5.91 C12 3 -5.93 C13 3 -5.90 C14 3 -5.92 C15 3 -5.92 C16 3 -5.91 C17 5 -5.92 C18 5 -5.94 C19 3 -5.88 C20 1 -5.85 C21 3 -5.83 DB01 1 -5.63 DB02 3 -5.71 DB03 3 -5.75 DB04 5 Unable to detect DB05 3 -5.72 DB06 0 -5.70 DB07 3 -5.69

[0127] It can be seen from the above results that except for the HOMO energy level of DB04 which could not be measured, the HOMO energy levels of the materials of the present invention are all relatively deep, which makes the materials of the present invention have a certain ability to resist holes and excitons. In addition, the materials of the present invention have relatively more complexing sites, which is conducive to the coordination and complexing with the metal-doped materials, increasing the stability of the complex, and preventing the metal-doped materials from being freed to the pCGL layer to cause material degradation, thereby causing the device life to decrease and the voltage to increase.

[0128] Fabrication and characterization of OLEDs

[0129] Device Embodiment

[0130] 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;

[0131] 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.

[0132] 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.

[0133] 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.

[0134] 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.).

[0135] 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:

[0136] Device Example 1

[0137] 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.

[0138] Subsequently, HT01 and PD01 (the mass ratio of HT01 to PD01 is 97:3) are vacuum deposited on the ITO layer (anode) formed on the substrate with a thickness of 10 nm to form a hole injection layer; secondly, HT01 is vacuum deposited on the hole injection layer with a thickness of 15 nm to form a first hole transport layer, and secondly, BP01 is vacuum deposited on the first hole transport layer with a thickness of 5 nm to form a first electron blocking layer, and secondly, a mixture of BH01 and BD01 is vacuum deposited on the first electron blocking layer with a thickness of 20 nm to form a first light-emitting layer, wherein BH01 is used as the main component, BD01 is a dopant, and the mass ratio of the host to the dopant is 98:2; then, on the first light-emitting layer, HB01 is vacuum deposited with a thickness of 5 nm to form a first hole blocking layer; then, on the first hole blocking layer, ET01 and LiQ (the mass ratio of ET01 to Liq is 1:1) are vacuum deposited with a thickness of 15 nm to form a first electron transport layer; then, on the first electron transport layer, C1 and Yb (the mass ratio of C1 to Yb is 98:2) are vacuum deposited with a thickness of 10 nm to form an n-type charge generation layer, and HT01 and PD01 (HT0 1 and PD01 with a mass ratio of 97:3) to form a p-type charge generation layer, and then on the p-type charge generation layer, HT01 was vacuum deposited with a thickness of 15nm to form a second hole transport layer, and then on the second hole transport layer, BP01 was 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 BH01 and BD01 was vacuum deposited with a thickness of 20nm to form a second light-emitting layer, wherein BH01 was used as a host and BD01 was used as a dopant, and the mass ratio of the host to the dopant was 98:2; then on the second light-emitting layer, 5n m thick HB01 was vacuum deposited to form a second hole blocking layer; then on the above second hole blocking layer, ET01 and LiQ (the mass ratio of ET01 to Liq is 1:1) were vacuum deposited to form a second electron transport layer; then on the above second electron transport layer, Yb was deposited to a thickness of 1nm to form an electron injection layer, and then on the above electron injection layer, Mg and Ag (the mass ratio of Mg and Ag is 1:9) were deposited to a thickness of 15nm to form a cathode, and then on the above cathode, CP01 was deposited to a thickness of 50nm to form a covering layer to prepare a stacked organic electroluminescent device.

[0139] 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:

[0140]

[0141] Device Example 2-21

[0142] 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.

[0143] Device Comparison Examples 1-7

[0144] The above method was used to prepare the compounds described in the examples into organic electroluminescent devices, wherein DB01 to DB05 were used to replace C1 to prepare organic electroluminescent device comparative examples 1-7.

[0145] 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 = 30 mA / cm 2 When working under this condition, the luminous brightness drops to its initial value L after time LT97. 0 97% of the total.

[0146] The test instruments and methods for testing the performance of the OLED devices in the above embodiments and comparative examples are as follows:

[0147] The luminous efficiency CE (cd / A) and color coordinates (CIEy) were tested using a spectrum scanner PhotoResearch PR-655;

[0148] Current density and lighting voltage: tested using a digital source meter Keithley 2400;

[0149] 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);

[0150] Life test: Use silicon photoelectric OLED device life test system.

[0151] The performance test results of the above devices are listed in Table 2.

[0152] Table 2 Device performance test results

[0153] Devices Material Driving voltage(V) BI(cd / A / CIEy) LT97(h) Device Example 1 C1 6.48 334 187 Device Example 2 C2 6.49 332 189 Device Example 3 C3 6.48 332 185 Device Example 4 C4 6.49 335 185 Device Example 5 C5 6.43 337 193 Device Example 6 C6 6.41 338 197 Device Example 7 C7 6.42 336 194 Device Example 8 C8 6.43 337 190 Device Example 9 C9 6.59 323 179 Device Example 10 C10 6.55 324 179 Device Example 11 C11 6.55 324 177 Device Example 12 C12 6.55 321 179 Device Example 13 C13 6.54 329 181 Device Example 14 C14 6.51 328 183 Device Example 15 C15 6.51 329 181 Device Example 16 C16 6.51 326 184 Device Example 17 C17 6.61 319 169 Device Example 18 C18 6.61 318 165 Device Example 19 C19 6.69 316 157 Device Example 20 C20 6.77 313 152 Device Example 21 C21 6.72 315 156 Device Comparison Example 1 DB01 6.88 298 138 Device Comparison Example 2 DB02 6.81 306 131 Device Comparison Example 3 DB03 6.87 294 113 Device Comparison Example 4 DB04 6.88 304 130 Device Comparison Example 5 DB05 6.89 295 136 Device Comparative Example 6 DB06 6.94 301 114 Device Comparison Example 7 DB07 6.84 303 119

[0154] As can be seen from the above table, compared with device comparative example 1, the present invention adopts a nitrogen-containing heterocycle as a connecting group, so that the molecule as a whole has good electron-withdrawing properties, which is beneficial to reduce the electron injection barrier, thereby improving the device performance. Compared with device comparative example 2, the preferred connection scheme of the present invention is to connect the pyridine in the middle of the terpyridine through a nitrogen-containing aromatic group and the phosphine oxygen group, which makes the complexation site not change with the rotation of the single bond, so that the complex is relatively stable. In addition, the bipyridylphenyl used in the present invention is connected to the phosphine oxygen fragment through a nitrogen-containing aromatic group, that is, more coordination sites are maintained. At the same time, the phenyl group also contains three electron-withdrawing groups, which can keep the molecule at a deeper energy level. The fewer electron-withdrawing groups on the terminal phenyl of comparative example 2 lead to a smaller electron-withdrawing effect, which may make the phenyl group's electron transmission effect not obvious, but make the phenyl group a steric hindering group, which is not conducive to material stacking, and thus may affect carrier transmission; compared with device comparative example 3, the terpyridine Directly connected to the phosphine oxide group, not only the molecular weight is small, but the direct connection of two strong electron-pulling fragments will also reduce the stability of the molecule. Compared with device comparison example 4, device comparison example 4 uses triazine and pyrimidine as strong electron-pulling groups, which will significantly affect the overall energy level of the molecule, and the strong electron-pulling groups are directly connected, which may affect the stability of the material. This effect may be more obvious on small molecular weight materials. Compared with device comparison example 5, device comparison example 5 uses oxobenzofuran as a connecting group. Although oxobenzofuran does not significantly affect the molecular energy level, compared with the nitrogen-containing heterocycle used in the present invention, the pyridine and other connecting groups of the present invention can participate in the coordination of the terpyridine fragment and increase the coordination and complexing sites, so that the present invention has better device performance. Compared with comparison example 6, the fragment lacks a chelating group, which is not conducive to voltage reduction; compared with comparison example 7, the fragment lacks a strong electron-pulling phosphine oxide group, which may be not conducive to voltage reduction due to energy level mismatch.

[0155] 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. A polypyridine compound containing a phosphine oxygen group, characterized in that: The general structural formula of the polypyridine compound is shown in Formula I: Wherein, X represents C or N; L represents a substituted or unsubstituted C5 to C20 nitrogen-containing aromatic ring; When L has a substituent, the substituent is selected from phenyl or deuterium; In formula I, any hydrogen may be replaced by deuterium, any nitrogen may be replaced by nitrogen-15, any oxygen may be replaced by oxygen-17 or oxygen-18, and any carbon may be replaced by carbon-13.

2. The polypyridine compound according to claim 1, characterized in that Said X represents N; The L represents one of substituted or unsubstituted pyridine, substituted or unsubstituted quinazoline, and substituted or unsubstituted quinoxaline.

3. The polypyridine compound according to claim 1, characterized in that The L represents One of them.

4. The polypyridine compound according to claim 1, characterized in that: The L represents One of them.

5. The polypyridine compound according to claim 1, characterized in that: The polypyridine compound is selected from one of the structures shown below:

6. Use of the polypyridine 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 polypyridine 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 polypyridine 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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