Phenanthroline derivative and organic electroluminescent device containing same

Abstract

The invention provides a phenanthroline derivative and an organic electroluminescent device containing the same. The structural general formula of the phenanthroline derivative is as shown in formula I. Phenyl, phenanthroline and nitrogen-substituted heteroaryl in the phenanthroline derivative provided by the invention are meta-substituted mutually, so that the material has a relatively large energy gap, and an N-type dopant can be prevented from diffusing to a luminescent layer to form a quenching center; the connection mode of four aromatic rings in nitrogen-substituted heteroaryl is limited, so that the planar molecular structure can be destroyed, the flexibility of the structure is maintained, and the crystallinity problem in the film forming process is improved; on the basis of the special connection mode, the nitrogen-substituted heteroaryl of the compound provided by the invention contains at least one pyridyl structure, so that the material has higher charge generation capacity, the driving voltage of a light-emitting device can be remarkably reduced, and the efficiency of the device can be improved. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the technical field of organic light-emitting semiconductors, and specifically comprises a phenanthroline derivative and an organic electroluminescent device comprising the same. Background Art

[0002] Organic light emitting diodes (OLEDs) have the advantages of self-luminescence, light weight, fast response speed, wide viewing angle and full-color display. They have made rapid progress in the fields of full-color display and solid-state lighting, and are regarded as a new generation of very promising ultra-high-definition display technology. Organic light emitting diodes are current-driven devices that can achieve the required brightness by increasing the current density of the device. For example, the brightness of a lighting source is required to be higher than 2000cd·m -2 , the working life is required to be greater than 50,000 hours. By increasing the current density, traditional devices can meet this brightness requirement. However, as the current density increases, the stability of organic materials in traditional devices decreases, and the luminous efficiency will be greatly reduced, resulting in serious efficiency roll-off and shortened device life. Therefore, it is difficult for traditional devices to have both high brightness and long life.

[0003] A tandem organic light-emitting diode (Tandem Organic Light-emitting Diode, tandem OLED) (abbreviated as tandem device) is composed of two or more independent electroluminescent units connected in series through a charge generation layer. Its luminous efficiency (current efficiency) increases linearly with the number of tandem light-emitting units, greatly improving the efficiency of the organic electroluminescent device. Since the life of an organic electroluminescent device is inversely proportional to its operating current, when the tandem device and the traditional device achieve the same brightness, the current flowing through the tandem device is one-Nth of that of the traditional device (assuming that the tandem device has N independent EL light-emitting units), which enables the tandem device to achieve higher brightness at a lower current density, greatly improving the life of the device. Therefore, from the perspective of device structure, it is a very effective method to use a tandem structure to obtain an organic electroluminescent device with high brightness, high efficiency and long life.

[0004] At present, stacked organic electroluminescent devices still have the following problems: (1) The commonly used charge generation layer materials have a rigid, electron-deficient planar molecular structure. Although they have good electron mobility, they have poor thermal stability and are easy to crystallize. When they are applied to OLED display devices, they are prone to crystallization when powered on for a long time, and there is a problem of thin film turbidity; (2) Most of the N-type dopants used in the charge generation layer are active metals, which are extremely unstable in the air and difficult to control, which increases the complexity of device preparation. In addition, some dopants such as Li and Cs have a long ion diffusion distance and are very easy to diffuse into the light-emitting layer to form quenching centers, which have a strong quenching effect on the luminescence and greatly reduce the efficiency of the device; (3) Although the current efficiency, device brightness and other parameters of stacked devices are multiplied compared with traditional devices, their driving voltage is also multiplied, which seriously restricts the development and commercialization of organic electroluminescent devices. Summary of the invention

[0005] In view of this, the present invention provides a phenanthroline derivative and an organic electroluminescent device comprising the same. The phenanthroline derivative has a large molecular weight, is not easy to crystallize, and has a strong charge generation ability. The phenanthroline derivative provided by the present invention is used as an N-type charge generation layer material in the charge generation layer of a stacked organic electroluminescent device. The N-type charge generation layer material is well coordinated with an N-type dopant, has a strong charge generation ability, is not easy to crystallize, can significantly reduce the driving voltage of the stacked organic electroluminescent device, and can increase the control of the N-type dopant, thereby improving the efficiency of the stacked organic electroluminescent device, and overcoming the defects of the prior art.

[0006] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0007] The first aspect of the present invention provides a phenanthroline derivative, the general structural formula of the phenanthroline derivative is shown in Formula I:

[0008]

[0009] Among them, the X 11 To X 13 , X 21 To X 23 , X 31 To X 34 , X 41 To X 43 are the same or different from each other and are independently selected from CH or N, wherein X 11 To X 43 (i.e. X 11 To X 13 , X 21 To X 23 , X 31 To X 34, X 41 To X 43 ) at least one of which is selected from N, and when containing 2 or more N, N are not on the same aromatic ring.

[0010] In combination with the first aspect, the X 11 To X 43 Two of them are selected from N, and the two N are not on the same aromatic ring.

[0011] In combination with the first aspect, the X 11 To X 43 Among them, three are selected from N, and the three N are not on the same aromatic ring.

[0012] In combination with the first aspect, the X 11 To X 43 Among them, four are selected from N, and the four N are not on the same aromatic ring.

[0013] In combination with the first aspect, the phenanthroline derivative represented by formula I is selected from any one of the structures represented by formula I-1 to formula I-12 below:

[0014]

[0015]

[0016] In the structures shown in Formula I-1 to Formula I-12, the X 11 To X 13 There is one selected from N, the X 21 To X 23 There is one selected from N, the X 31 To X 34 There is one selected from N, the X 41 To X 43 One of them is selected from N.

[0017] In combination with the first aspect, the phenanthroline derivative represented by formula I is selected from any one of the structures represented by formula I-13 to formula I-18 below:

[0018]

[0019]

[0020] In the structures shown in Formula I-13 to Formula I-16, the X 11 To X 13 There is one selected from N, the X 21 To X 23 There is one selected from N, the X 31 To X 34 One of them is selected from N;

[0021] In the structures shown in Formula I-17 to Formula I-18, the X 11 To X 43 One of them is selected from N.

[0022] In combination with the first aspect, the phenanthroline derivative represented by formula I is selected from any one of the following compounds:

[0023]

[0024]

[0025] The second aspect of the present invention provides the use of the phenanthroline derivatives described above in the preparation of organic electroluminescent devices.

[0026] The third aspect of the present invention provides an organic electroluminescent device, comprising:

[0027] a first electrode;

[0028] A second electrode is disposed face to face with the first electrode;

[0029] A first light-emitting portion, located between the first electrode and the second electrode, comprising a first light-emitting layer and a first electron transport layer;

[0030] A second light-emitting portion, located between the first light-emitting portion and the second electrode, comprising a second light-emitting layer and a second electron transport layer; and

[0031] A charge generation layer is located between the first light-emitting portion and the second light-emitting portion, wherein the charge generation layer includes one or more phenanthroline derivatives as described above.

[0032] In combination with the third aspect, the charge generation layer includes a P-type charge generation layer and an N-type charge generation layer, the N-type charge generation layer is located between the P-type charge generation layer and the first light-emitting portion, wherein the N-type charge generation layer includes one or more phenanthroline derivatives as described above.

[0033] The beneficial effects of the present invention are as follows:

[0034] The phenanthroline derivative provided by the present invention uses formula I as a mother core, and the mother core is composed of a phenyl group, a phenanthroline group and a nitrogen-substituted heteroaryl group. The present invention limits the connection mode and connection site of the phenyl group, the phenanthroline group and the nitrogen-substituted heteroaryl group, so that the material has a larger energy gap and can block N-type dopants such as Li, Cs, etc. from diffusing into the light-emitting layer to form a quenching center; on the basis of the above connection mode, the present invention further limits the connection mode of the four aromatic rings in the nitrogen-substituted heteroaryl group, and the special connection mode can destroy the planar molecular structure, maintain the flexibility of the structure, and improve the crystallinity problem in the film forming process; on the basis of the above special connection mode, the present invention limits the nitrogen-substituted heteroaryl group to contain at least one pyridyl structure, so that the material provided by the present invention is well coordinated with the N-type dopant and has a high The invention discloses a method for improving the charge generation ability of a laminated organic electroluminescent device by using a phenanthroline derivative as an N-type charge generation layer material in a charge generation layer of a laminated organic electroluminescent device. The N-type charge generation layer material has a large molecular weight, is not easy to crystallize, and can effectively avoid the problem of thin film turbidity. The N-type charge generation layer material has a strong charge generation ability, is conducive to the injection and transmission of electrons, and can significantly reduce the driving voltage of the laminated organic electroluminescent device. The phenanthroline derivative as an N-type charge generation layer material can coordinate with an N-type dopant to form a complex, and can also block N-type dopants such as Li, Cs, etc. from diffusing into the light-emitting layer to form a quenching center, thereby enhancing the control of the N-type dopant, thereby improving the efficiency of the laminated organic electroluminescent device, and overcoming the defects of the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0036] Figure 1 It is a schematic structural diagram of an organic electroluminescent device containing a phenanthroline derivative of the present invention;

[0037] Description of the drawings: 1-anode, 2-hole injection layer, 3-first hole transport layer, 4-first light-emitting layer, 5-first electron transport layer, 6-N-type charge generation layer, 7-P-type charge generation layer, 8-second hole transport layer, 9-second light-emitting layer, 10-second electron transport layer, 11-electron injection layer, 12-cathode. DETAILED DESCRIPTION

[0038] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. Similar components in the accompanying drawings are represented by the same figure numerals. It should be understood by those skilled in the art that the content specifically described below is illustrative and not restrictive, and the protection scope of the present invention should not be limited to this. The embodiments and comparative examples of this specification are provided to more completely explain this specification to those skilled in the art. According to the embodiments and comparative examples of this specification, various different forms can be deformed, and the protection scope of the present invention should not be limited only to the embodiments and comparative examples described in detail below.

[0039] The phenanthroline derivative compounds of the present invention are suitable for use in light-emitting elements, display panels and electronic devices, and are 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, which may also comprise a layer formed by an inorganic material or a layer formed entirely by an inorganic material. The electronic device is preferably an organic electroluminescent device (OLED), an organic integrated circuit (O-IC), an organic field effect transistor (O-FET), an organic thin film transistor (O-TFT), an organic light emitting transistor (O-LET), an organic solar cell (O-SC), an organic dye-sensitized solar cell (O-DSSC), an organic optical detector, an organic photoreceptor, an organic field quenching device (O-FQD), a light-emitting electrochemical cell (LEC), an organic laser diode (O-laser) and an organic plasma emission device. The electronic device is most preferably an organic electroluminescent device (OLED).

[0040] The phenanthroline derivative of the present invention is prepared by using a representative reaction, Buchwald-Hartwig coupling reaction, Suzuki coupling reaction or Heck coupling reaction.

[0041] In order to understand content of the present invention more clearly, the preparation method of phenanthroline derivatives, phenanthroline derivatives and the luminescent characteristics of devices will be explained in detail in conjunction with examples. Various chemical reactions can be applied to the synthetic method of the compound of an embodiment of the present invention. But it should be noted that the synthetic method of the compound of an embodiment of the present invention is not limited to the synthetic method described below. Unless otherwise indicated, the following building-up process is all carried out under protective gas atmosphere and in anhydrous solvent. Solvent and reagent can be purchased from conventional reagent suppliers.

[0042] Intermediate synthesis

[0043] Intermediate A

[0044]

[0045] Under nitrogen protection, sub-1 (12 g; 0.1 mol), sub-2 (17.2 g; 0.1 mol), potassium hydroxide (14 g; 0.25 mol) and ethanol (EtOH) (500 mL) were mixed, heated to 80°C and refluxed for 6 hours under stirring, then cooled to 25°C, and then separated using 500 mL of toluene and 500 mL of saturated brine to obtain an aqueous phase and an organic phase; the aqueous phase was extracted twice with 500 mL of toluene, the upper liquid obtained by the extraction was mixed with the organic phase, the organic phase mixture was dehydrated and dried using anhydrous sodium sulfate, the desiccant was filtered, and the dried organic phase mixture was rotary evaporated to remove the organic solvent, and finally the product A: 14.08 g (yield: 55%), MS (m / z) (M+): 256.

[0046] Intermediate Bz

[0047]

[0048] In the general synthetic formula of intermediate Bz, X 11 To X 13 , X 21 To X 23 , X 31 To X 34 , X 41 To X 43 are the same or different from each other and are independently selected from CH or N, X 11 To X 43 At least one of the N atoms is selected from N, and when it contains 2 or more N atoms, the N atoms are not on the same aromatic ring.

[0049] The general synthesis formula of intermediate Bz is as above. Under nitrogen protection, sub-x (0.11 mol), sub-y (0.1 mol) and sodium carbonate (21.20 g, 0.2 mol) were added to 300 mL of a mixed solvent of toluene, ethanol (EtOH) and water (the volume ratio of toluene, water and ethanol was 8:3:1), and PdCl2(PPh3)2 (1.40 g, 2 mmol) was introduced. The reaction system was then heated to 80°C, refluxed and maintained for 5 hours, cooled to room temperature, added with 200 mL of deionized water, stirred for 20 minutes, and then separated. The organic phase was dried with anhydrous sodium sulfate, and the solvent was removed by rotary evaporation to obtain a crude product. The crude product was purified by recrystallization from toluene and ethanol.

[0050] Intermediate Bz Example 1

[0051] This example provides a compound B-1, the synthesis route of which is as follows:

[0052]

[0053] Under nitrogen protection, sub-3 (39.71 g; 0.11 mol), sub-4 (19.8 g; 0.1 mol) and sodium carbonate (21.20 g, 0.2 mol) were added to 300 mL of a mixed solvent of toluene, ethanol and water (the volume ratio of toluene, water and ethanol was 8:3:1), PdCl2(PPh3)2 (1.40 g, 2 mmol) was introduced, and then the reaction system was heated to 80 ° C, refluxed and maintained for 5 hours, cooled to room temperature, added 200 mL of deionized water, stirred for 20 minutes, and then separated. The organic phase was dried with anhydrous sodium sulfate, and the solvent was removed by rotary evaporation to obtain a crude product, which was purified by recrystallization from toluene and ethanol. Finally, the product B-1: 25.15 g (yield: 65%), MS (m / z) (M+): 387 was obtained.

[0054] After intermediate B-1 is obtained through the above process, other intermediates B-2 to B-40 can be obtained by using a method basically the same as that for synthesizing intermediate B-1, except that the reactants are different. The chemical formulas of intermediates B-2 to B-40 are shown in the following compound synthesis examples.

[0055] Compound Example 1

[0056] This example provides a compound C-1, the synthesis route of which is as follows:

[0057]

[0058] Under nitrogen protection, B-1 (12.38 g; 32 mmol) was dissolved in dibutyl ether (30 mL) to obtain B-1 solution. At -10 ° C, n-butyl lithium (nBuLi) (1.6 M, 20 mL) was slowly added to the B-1 solution, the temperature was raised to 0 ° C and stirred for 0.5 h, and the temperature was slowly lowered to -5 ° C. Then, a toluene (160 mL) solution dissolved with A (8.19 g; 32 mmol) at -10 ° C was slowly added. The temperature was kept below -5 ° C during the addition process. After the addition was completed, it was stirred for 2 hours, and then 200 mL of water was used to quench the reaction, and the liquid was separated to obtain an organic phase;

[0059] The organic phase was washed three times with deionized water, each time with 30 mL of deionized water, separated, and the organic phases were combined. The combined organic phases were then dried over anhydrous sodium sulfate, and the solid sodium sulfate was removed by solid-liquid separation. The resulting liquid was evaporated to remove the solvent, 300 mL of tetrahydrofuran was added, and stirred to dissolve, manganese dioxide (16.70 g, 0.19 mol) was added and stirred at room temperature for 10 h, and then 200 mL of tetrahydrofuran was added and stirred for 30 min. The reaction solution was filtered for insoluble matter using diatomaceous earth to obtain a filtrate, and the filtrate was evaporated to remove the solvent to obtain a crude product. The crude product was recrystallized using toluene / n-heptane to finally obtain product C-1: 12.07 g (yield: 67%), MS (m / z) (M+): 563.

[0060] Compound Example 2

[0061] This example provides a compound C-2, the synthesis route of which is as follows:

[0062]

[0063] The method is the same as compound Example 1, except that B-1 is replaced by an equimolar amount of B-2 (12.38 g; 32 mmol), and the final product C-2 is obtained: 14.59 g (yield: 81%), MS (m / z) (M+): 563.

[0064] Compound Example 3

[0065] This example provides a compound C-3, the synthesis route of which is as follows:

[0066]

[0067] The method is the same as compound Example 1, except that B-1 is replaced by an equimolar amount of B-3 (12.38 g; 32 mmol), and the final product C-3 is obtained: 15.13 g (yield: 84%), MS (m / z) (M+): 563.

[0068] Compound Example 4

[0069] This embodiment provides a compound C-4, the synthesis route of which is as follows:

[0070]

[0071] The method is the same as compound Example 1, except that B-1 is replaced by an equal molar amount of B-4 (12.38 g; 32 mmol), and the final product C-4 is obtained: 13.33 g (yield: 74%), MS (m / z) (M+): 563.

[0072] Compound Example 5

[0073] This embodiment provides a compound C-5, the synthesis route of the compound is as follows:

[0074]

[0075] The method is the same as compound Example 1, except that B-1 is replaced by an equimolar amount of B-5 (12.38 g; 32 mmol), and the final product C-5 is obtained: 13.87 g (yield: 77%), MS (m / z) (M+): 563.

[0076] Compound Example 6

[0077] This embodiment provides a compound C-6, the synthesis route of the compound is as follows:

[0078]

[0079] The method is the same as compound Example 1, except that B-1 is replaced by an equal molar amount of B-6 (12.38 g; 32 mmol), and the final product C-6 is obtained: 12.61 g (yield: 70%), MS (m / z) (M+): 563.

[0080] Compound Example 7

[0081] This embodiment provides a compound C-7, the synthesis route of which is as follows:

[0082]

[0083] The method is the same as compound Example 1, except that B-1 is replaced by an equimolar amount of B-7 (12.38 g; 32 mmol), and the final product C-7 is obtained: 12.07 g (yield: 67%), MS (m / z) (M+): 563.

[0084] Compound Example 8

[0085] This embodiment provides a compound C-8, the synthesis route of the compound is as follows:

[0086]

[0087] The method is the same as compound Example 1, except that B-1 is replaced by an equal molar amount of B-8 (12.38 g; 32 mmol), and the final product C-8 is obtained: 12.25 g (yield: 68%), MS (m / z) (M+): 563.

[0088] Compound Example 9

[0089] This embodiment provides a compound C-9, the synthesis route of the compound is as follows:

[0090]

[0091] The method is the same as compound Example 1, except that B-1 is replaced by an equal molar amount of B-9 (12.38 g; 32 mmol), and the final product C-9 is obtained: 13.15 g (yield: 73%), MS (m / z) (M+): 563.

[0092] Compound Example 10

[0093] This embodiment provides a compound C-10, the synthesis route of the compound is as follows:

[0094]

[0095] The method is the same as compound Example 1, except that B-1 is replaced by an equal molar amount of B-10 (12.38 g; 32 mmol), and the final product C-10 is obtained: 15.13 g (yield: 84%), MS (m / z) (M+): 563.

[0096] Compound Example 11

[0097] This example provides a compound C-11, the synthesis route of the compound is as follows:

[0098]

[0099] The method is the same as compound Example 1, except that B-1 is replaced by an equal molar amount of B-11 (12.38 g; 32 mmol), and the final product C-11 is obtained: 11.71 g (yield: 65%), MS (m / z) (M+): 563.

[0100] Compound Example 12

[0101] This embodiment provides a compound C-12, the synthesis route of the compound is as follows:

[0102]

[0103] The method is the same as compound Example 1, except that B-1 is replaced by an equal molar amount of B-12 (12.38 g; 32 mmol), and the final product C-12 is obtained: 14.95 g (yield: 83%), MS (m / z) (M+): 563.

[0104] Compound Example 13

[0105] This embodiment provides a compound C-13, the synthesis route of the compound is as follows:

[0106]

[0107] The method is the same as compound Example 1, except that B-1 is replaced by an equal molar amount of B-13 (12.38 g; 32 mmol), and the final product C-13 is obtained: 14.05 g (yield: 78%), MS (m / z) (M+): 563.

[0108] Compound Example 14

[0109] This embodiment provides a compound C-14, the synthesis route of the compound is as follows:

[0110]

[0111] The method is the same as compound Example 1, except that B-1 is replaced by an equal molar amount of B-14 (12.38 g; 32 mmol), and the final product C-14 is obtained: 12.25 g (yield: 68%), MS (m / z) (M+): 563.

[0112] Compound Example 15

[0113] This embodiment provides a compound C-15, the synthesis route of the compound is as follows:

[0114]

[0115] The method is the same as compound Example 1, except that B-1 is replaced by an equal molar amount of B-15 (12.38 g; 32 mmol), and the final product C-15 is obtained: 14.59 g (yield: 81%), MS (m / z) (M+): 563.

[0116] Compound Example 16

[0117] This embodiment provides a compound C-16, the synthesis route of the compound is as follows:

[0118]

[0119] The method is the same as compound Example 1, except that B-1 is replaced by an equal molar amount of B-16 (12.38 g; 32 mmol), and the final product C-16 is obtained: 13.69 g (yield: 76%), MS (m / z) (M+): 563.

[0120] Compound Example 17

[0121] This embodiment provides a compound C-17, the synthesis route of the compound is as follows:

[0122]

[0123] The method is the same as compound Example 1, except that B-1 is replaced by an equal molar amount of B-17 (12.42 g; 32 mmol), and the final product C-17 is obtained: 13.36 g (yield: 74%), MS (m / z) (M+): 564.

[0124] Compound Example 18

[0125] This embodiment provides a compound C-18, the synthesis route of the compound is as follows:

[0126]

[0127] The method is the same as compound Example 1, except that B-1 is replaced by an equal molar amount of B-18 (12.45 g; 32 mmol), and the final product C-18 is obtained: 14.28 g (yield: 79%), MS (m / z) (M+): 565.

[0128] Compound Example 19

[0129] This embodiment provides a compound C-19, the synthesis route of the compound is as follows:

[0130]

[0131] The method is the same as compound Example 1, except that B-1 is replaced by an equal molar amount of B-19 (12.45 g; 32 mmol), and the final product C-19 is obtained: 13.02 g (yield: 72%), MS (m / z) (M+): 565.

[0132] Compound Example 20

[0133] This embodiment provides a compound C-20, the synthesis route of the compound is as follows:

[0134]

[0135] The method is the same as compound Example 1, except that B-1 is replaced by an equal molar amount of B-20 (12.42 g; 32 mmol), and the final product C-20 is obtained: 14.98 g (yield: 83%), MS (m / z) (M+): 564.

[0136] Compound Comparative Example 1

[0137] This comparative example provides a compound D1 used in the experiment during the research process, and its specific structural formula is:

[0138]

[0139] Compound Comparative Example 2

[0140] This comparative example provides a compound D2 used in the experiment during the research process, and its specific structural formula is:

[0141]

[0142] Compound Comparative Example 3

[0143] This comparative example provides a compound D3 used in the experiment during the research process, and its specific structural formula is:

[0144]

[0145] Compound Comparative Example 4

[0146] This comparative example provides a compound D4 used in the experiment during the research process, and its specific structural formula is:

[0147]

[0148] Compound performance evaluation

[0149] The phenanthroline derivative provided by the present invention can be used as an N-type charge generation layer material in the charge generation layer of a stacked organic electroluminescent device. The N-type charge generation layer material has good coordination ability with an N-type dopant, has a strong charge generation ability, is not easy to crystallize, and can significantly reduce the driving voltage of the stacked organic electroluminescent device. Since the phenanthroline derivative of the present invention has the excellent properties as described above, it can be applied to charge generation layer materials, light-emitting elements, light-emitting devices or electronic devices.

[0150] The structure of the experimental device of the present invention is as follows:

[0151] Indium tin oxide (ITO: Indium Tin Oxide) / lithium (Li) (thickness 1nm) / ET-01 (thickness 10nm) / charge generation layer (thickness 25nm) / HTL (thickness 10nm) / p-dopant (thickness 1nm) / aluminum (Al) (thickness 100nm), wherein the structure of the charge generation layer is: a mixture of compound C-1 and Li (the mass ratio of C-1 to Li is 98:2) (thickness 15nm) / a mixture of HTL and p-dopant (the mass ratio of HTL to p-dopant is 95:5) (thickness 10nm).

[0152] Experimental method: All devices in this experiment were prepared on a glass substrate with patterned ITO. First, the ITO glass substrate was ultrasonically cleaned 3 times with deionized water and an ultrasonic cleaner, each time for 15 minutes. Next, the ITO glass substrate was blown dry with a nitrogen gun and placed in an oven at 120°C for 10 minutes to remove moisture from the surface of the ITO glass substrate. The ITO glass substrate was then placed in a plasma cleaner for 5 minutes to remove tiny particles and organic matter on the surface of the substrate and to improve the work function of ITO. The ITO glass substrate was placed in a vacuum thermal evaporation device, and the pressure in the evaporation chamber was maintained below 6×10 -5 Pa, according to the above experimental device structure, various functional layers and electrodes were evaporated on the ITO glass substrate in sequence to prepare the experimental device 1.

[0153] The compound C-1 in the charge generation layer structure of the experimental device 1 was replaced by compounds C-2 to C-20 and compounds D1 to D4, respectively, and the same method as above was used to prepare experimental devices 2 to 20 and comparative experimental devices 1 to 4.

[0154] The current density of the packaged experimental device corresponding to the voltage of 3V, 5V, and 7V was tested at room temperature using a digital source meter Keithley 2400. The specific test results are shown in Table 1:

[0155] The magnitude of the current density can reflect the strength of the compound's charge generation ability. Under the same voltage, the larger the current density, the more charge the compound generates and the stronger its charge generation ability.

[0156] Table 1 Compound performance test results

[0157]

[0158]

[0159] It can be seen from the test results in Table 1 that the current densities corresponding to the compounds C-1 to C-20 provided by the present invention at voltages of 3V, 5V, and 7V are significantly higher than the current densities of the compounds D1 to D4 provided in the comparative examples, indicating that the charge generation ability of the compounds provided by the present invention is significantly better than that of the comparative example compounds. The stronger the charge generation ability of the charge generation layer, the more conducive it is to reducing the driving voltage of the stacked organic electroluminescent device.

[0160] Device Embodiment

[0161] The organic electroluminescent device provided by the present invention comprises: a first electrode and a second electrode facing each other, a first light-emitting portion, a second light-emitting portion and a charge generation layer;

[0162] The first light-emitting portion is located between the first electrode and the second electrode, and includes a first light-emitting layer 4 and a first electron transport layer 5;

[0163] The second light-emitting portion is located between the first light-emitting portion and the second electrode, and includes a second light-emitting layer 9 and a second electron transport layer 10;

[0164] The charge generation layer is located between the first light-emitting portion and the second light-emitting portion, and includes an N-type charge generation layer 6 and a P-type charge generation layer 7, wherein the N-type charge generation layer 6 includes one or more compounds C-1 to C-20 in the compound embodiments.

[0165] This embodiment is described by taking the first electrode as the anode 1 and the second electrode as the cathode 12. Figure 1 As shown, it includes an anode 1, a hole injection layer 2, a first hole transport layer 3, a first light-emitting layer 4, a first electron transport layer 5, an N-type charge generation layer 6, a P-type charge generation layer 7, a second hole transport layer 8, a second light-emitting layer 9, a second electron transport layer 10, an electron injection layer 11, and a cathode 12, which are sequentially arranged on a substrate;

[0166] Furthermore, the first light-emitting layer 4 and the second light-emitting layer 9 are composed of a main material and a doping material, and the main material can be composed of one molecular material or a plurality of molecular materials.

[0167] The anode 1 in the embodiment adopts anode materials commonly used in the art, such as ITO, Ag or their multilayer structures. The hole injection layer 2 adopts hole injection materials commonly used in the art, and F4TCNQ, HATCN, NDP-9, etc. are added for doping. The hole transport layer (including the first hole transport layer 3 and the second hole transport layer 8) adopts hole transport materials commonly used in the art. The light-emitting layer (including the first light-emitting layer 4 and the second light-emitting layer 9) adopts light-emitting materials commonly used in the art, for example, it can be composed of a main material and a doping material, and the doping material is a doping material commonly used in the art. The electron transport layer (including the first electron transport layer 5 and the second electron transport layer 10) adopts electron transport materials commonly used in the art. The electron injection layer 11 adopts electron injection materials commonly used in the art, such as Liq (8-hydroxyquinoline-lithium), LiF, Yb, etc. The cathode 12 adopts materials commonly used in the art, such as metal Al, Ag or metal mixtures (Ag-doped Mg, Ag-doped Ca, etc.).

[0168] 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:

[0169] Device Example 1

[0170] The present embodiment provides a laminated organic electroluminescent device, and the specific preparation method thereof is as follows: an ITO substrate is patterned so that its luminous area is 2 mm×2 mm, and the ITO substrate is washed with isopropyl alcohol, ultraviolet (UV) and ozone respectively, and the ITO substrate is mounted on a substrate support of a vacuum deposition device and the pressure is adjusted so that the vacuum rate becomes 1×10 -7 torr; on the ITO layer (anode 1) formed on the substrate, HTL and p-dopant were vacuum deposited with a thickness of 5 nm (the mass ratio of HTL to p-dopant was 97:3) to form a hole injection layer 2; on the hole injection layer 2, HTL was vacuum deposited with a thickness of 35 nm to form a first hole transport layer 3; on the first hole transport layer 3, a mixture of YH and YD was vacuum deposited with a thickness of 30 nm to form a first light-emitting layer 4, wherein YH was used as a host and YD was used as a dopant, and the mass ratio of the host to the dopant was 98:2; then, on the first light-emitting layer 4, ET-01 was vacuum deposited with a thickness of 25 nm to form a first electron transport layer 5; on the first electron transport layer 5, compound C-1 and metal Li (the mass ratio of C-1 to Li was 98:2) were vacuum deposited with a thickness of 10 nm to form an N-type charge generation layer A generation layer 6 is formed; HTL and p-dopant are vacuum deposited with a thickness of 5 nm (the mass ratio of HTL to p-dopant is 97:3) to form a P-type charge generation layer 7; on the above-mentioned P-type charge generation layer 7, HTL is vacuum deposited with a thickness of 35 nm to form a second hole transport layer 8; on the above-mentioned second hole transport layer 8, a mixture of YH and YD is vacuum deposited with a thickness of 30 nm to form a second light-emitting layer 9, wherein YH is used as a host and YD is used as a dopant, and the mass ratio of the host to the dopant is 98:2; then on the above-mentioned second light-emitting layer 9, ET-01 is vacuum deposited with a thickness of 25 nm to form a second electron transport layer 10; LiF is deposited with a thickness of 1 nm to form an electron injection layer 11, and finally on the above-mentioned electron injection layer 11, aluminum (Al) is deposited with a thickness of 100 nm to form a cathode 12, and a stacked organic electroluminescent device is prepared.

[0171] Except for the N-type charge generation layer 6, the molecular structures of the remaining layers are as follows:

[0172]

[0173] Device Examples 2-20

[0174] The preparation method is the same as that of Device Example 1, except that Compound C-1 is replaced by Compounds C-2 to C-20 in Compound Examples 2 to 20.

[0175] Device Comparison Examples 1-4

[0176] The preparation method is the same as that of device example 1, except that compound C-1 is replaced by compounds D1, D2, D3, and D4 in comparative examples 1-4, respectively.

[0177] Performance evaluation of organic electroluminescent devices

[0178] Effect example

[0179] The organic electroluminescent devices provided in device examples 1-20 and device comparison examples 1-4 were tested by standard methods. For this purpose, at a current density J = 10 mA / cm 2 The driving voltage, brightness, electroluminescent current efficiency (measured in cd / A) and external quantum efficiency (EQE, measured in percentage) of the organic electroluminescent device are determined as a function of the luminous density from the current / voltage / luminous density characteristic line (IVL characteristic line) showing Lambertian emission characteristics. The lifetime LT is defined as the time after which the brightness drops from the initial luminous brightness L0 to a specific proportion L1 when operating at a constant current density J; J = 50 mA / cm 2 The expression L1 = 90% means that at 50 mA / cm 2 When working under LT, the luminous brightness drops to 90% of its initial luminous brightness L0 after time LT. Similarly, J = 20 mA / cm 2 , L1 = 80% means, at 20mA / cm 2 When working under this condition, the luminous brightness drops to 80% of its initial luminous brightness L0 after time LT.

[0180] The data of various OLED devices are summarized in Table 2. Various parameters of the embodiments are compared with those of the comparative examples, and the performance data of various OLED devices are shown.

[0181] The test instruments and methods for testing the performance of the OLED devices in the above embodiments and comparative examples are as follows:

[0182] Brightness was tested using a spectral scanner PhotoResearch PR-635;

[0183] Current density and lighting voltage: tested using a digital source meter Keithley 2400;

[0184] Life test: Use LT-96ch life test device.

[0185] The performance test results of the above devices are listed in Table 2.

[0186] Table 2 Performance test results of stacked devices

[0187]

[0188]

[0189]

[0190]

[0191]

[0192] It can be seen from the device performance test results in Table 2 above that, compared with the comparative example, the driving voltage of the stacked organic electroluminescent device prepared by using the compounds C-1 to C-20 provided by the present invention as the N-type charge generation layer material is lower, and the current efficiency and EQE are both higher. Compared with the comparative example, the phenyl, phenanthroline and nitrogen-substituted heteroaryl groups in the compounds C-1 to C-20 provided by the present invention are mutually meta-substituted, so that the material has a larger energy gap, which can prevent N-type dopants such as Li, cesium (Cs), etc. from diffusing into the light-emitting layer to form a quenching center. Therefore, compared with the comparative example, the current efficiency of the stacked device provided by the present invention is higher; compared with the comparative example, the compounds C-1 to C-20 provided by the present invention all contain nitrogen-substituted heteroaryl groups of special structures. This application defines the connection method of the four aromatic rings in the nitrogen-substituted heteroaryl groups. , can destroy the planar molecular structure, maintain the flexibility of the structure, and improve the crystallinity problem in the film forming process; on the basis of this special connection mode, the nitrogen-substituted heteroaryl in the compounds C-1 to C-20 provided by the present invention contains at least one pyridyl structure, so that the material provided by the present invention has a higher charge generation ability, and further, the C-1, C-2, C-3, C-4, C-5, C-6, C-7, and C-8 provided by the present invention have relatively better charge generation ability, which is conducive to the injection and transmission of electrons, so the driving voltage is relatively lower. The performance effect of the stacked organic electroluminescent device prepared by using the compound provided by the present invention as the N-type charge generation layer material is significantly better than that of the comparative example, and the phenanthroline derivative provided by the present invention is used as the N-type charge generation layer material in the charge generation layer of the stacked organic electroluminescent device. The N-type charge generation layer material is well coordinated with the N-type dopant, has a strong charge generation ability, is not easy to crystallize, and can significantly reduce the driving voltage of the stacked organic electroluminescent device, and can increase the control of the N-type dopant, overcoming the defects of the prior art. This shows that the phenanthroline derivative provided by the present invention is an N-type charge generation layer material with good performance, can meet the performance requirements of stacked organic electroluminescent devices, and has practical value.

[0193] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A phenanthroline derivative, characterized in that The general structural formula of the phenanthroline derivative is shown in Formula I: Among them, the X 11 To X 13 , X 21 To X 23 , X 31 To X 34 , X 41 To X 43 are the same or different from each other and are independently selected from CH or N, wherein X 11 To X 43 At least one of the N atoms is selected from N, and when it contains 2 or more N atoms, the N atoms are not on the same aromatic ring.

2. The phenanthroline derivative according to claim 1, characterized in that The X 11 To X 43 Two of them are selected from N, and the two N are not on the same aromatic ring.

3. The phenanthroline derivative according to claim 1, characterized in that The X 11 To X 43 Among them, three are selected from N, and the three N are not on the same aromatic ring.

4. The phenanthroline derivative according to claim 1, characterized in that The X 11 To X 43 Among them, four are selected from N, and the four N are not on the same aromatic ring.

5. The phenanthroline derivative according to claim 1, characterized in that The phenanthroline derivative represented by formula I is selected from any one of the structures represented by the following formula I-1 to formula I-12: In the structures shown in Formula I-1 to Formula I-12, the X 11 To X 13 There is one selected from N, the X 21 To X 23 There is one selected from N, the X 31 To X 34 There is one selected from N, the X 41 To X 43 One of them is selected from N.

6. The phenanthroline derivative according to claim 1, characterized in that The phenanthroline derivative represented by formula I is selected from any one of the structures represented by the following formula I-13 to formula I-18: In the structures shown in Formula I-13 to Formula I-16, the X 11 To X 13 There is one selected from N, the X 21 To X 23 There is one selected from N, the X 31 To X 34 One of them is selected from N; In the structures shown in Formula I-17 to Formula I-18, the X 11 To X 43 One of them is selected from N.

7. The phenanthroline derivative according to claim 1, characterized in that The phenanthroline derivative represented by formula I is selected from any one of the following compounds:

8. Use of the phenanthroline derivative according to any one of claims 1 to 7 in the preparation of an organic electroluminescent device.

9. An organic electroluminescent device, characterized in that: include: a first electrode; A second electrode is disposed face to face with the first electrode; A first light-emitting portion, located between the first electrode and the second electrode, comprising a first light-emitting layer and a first electron transport layer; A second light-emitting portion, located between the first light-emitting portion and the second electrode, comprising a second light-emitting layer and a second electron transport layer; and A charge generation layer is located between the first light-emitting portion and the second light-emitting portion, wherein the charge generation layer comprises one or more phenanthroline derivatives as described in any one of claims 1 to 7.

10. The organic electroluminescent device according to claim 9, characterized in that: The charge generation layer includes a P-type charge generation layer and an N-type charge generation layer, and the N-type charge generation layer is located between the P-type charge generation layer and the first light-emitting portion, wherein the N-type charge generation layer includes one or more phenanthroline derivatives as described in any one of claims 1 to 7.

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