Adamantane fluorene compound and organic electroluminescent device thereof

Abstract

According to the adamantane fluorene compound and the organic electroluminescent device thereof provided by the invention, the triazine group is directly bonded with the adamantane fluorene group, and the electron transmission characteristic of the triazine group and the rigid structure of the adamantane fluorene group are utilized; meanwhile, a device structure which is formed by matching a compound I series as a hole blocking layer and a compound II series as an electron transport layer material, wherein a sub-aromatic group is inserted between the two groups of the hole blocking layer and the electron transport layer material is designed. The compound I series inherits excellent electron transport performance and film stability, has a lower HOMO track, can better prevent holes in a luminescent layer from overflowing, and can form ohmic contact with an electron transport layer material of the compound II series, so that the device structure is optimized to the maximum extent, and a device with excellent performance is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of organic electroluminescent materials, and in particular relates to an adamantane fluorene compound and an organic electroluminescent device thereof. Background Art

[0002] The simplest organic electroluminescent device (OLED) is a sandwich structure, which consists of electrodes on both sides and organic materials (light-emitting layer) added in between. In order to improve the efficiency and life of the device and give full play to the performance of organic materials, OLED devices are now multi-layered structures, introducing hole transport layer, electron transport layer, electron blocking layer, and light-emitting layer (obtained by co-evaporation of host and guest materials), and each layer of material has its own function.

[0003] As OLED application scenarios become more and more diverse, the requirements for its efficiency and life span are also diversified. In addition to the continuous development of new materials (device components) with excellent performance, the optimization of device structure is also an important means to improve device performance. In many cases, the electron region of the top-emitting device only has an electron transport layer that not only blocks the overflow of holes in the light-emitting layer, but also efficiently transmits electrons. Adding a hole blocking layer between the electron transport layer and the light-emitting layer can strip off the hole blocking properties of the electron transport layer material and only consider its electron transport performance, which simplifies its development to a certain extent. However, hole blocking layer materials with excellent performance must consider both their electron transport properties and hole blocking properties. Therefore, hole blocking layer materials have become a new hot spot for manufacturers' material development. Summary of the invention

[0004] In order to solve the problems existing in the background technology, the first object of the present invention is to provide an adamantane fluorene compound, and the technical scheme is as follows:

[0005] An adamantane fluorene compound has the following structure of general formula I:

[0006]

[0007] wherein Ar1 is the same or different and is selected from substituted or unsubstituted C6-C 30 when substituted, the substituent is selected from deuterium, fluorine, phenyl, naphthyl, cyano, pyridyl, and methyl.

[0008] As a preferred embodiment of the present invention, the Ar1 is the same or different and is selected from phenyl, naphthyl, biphenyl and terphenyl.

[0009] As a preferred embodiment of the present invention, the general formula I is one of the following structures:

[0010]

[0011]

[0012]

[0013]

[0014]

[0015]

[0016] Another object of the present invention is to provide an organic electroluminescent device, comprising a first electrode, a second electrode and an organic material layer arranged therebetween, wherein the organic material layer comprises an electron transport layer and a hole blocking layer, and the electron transport layer and / or the hole blocking layer are prepared from the above-mentioned adamantanefluorene compound.

[0017] As a preferred embodiment of the present invention, the hole blocking layer is prepared from the above-mentioned adamantane fluorene compound, and the electron transport layer is prepared from a compound of the general formula II structure, and the structure of the general formula II is as follows:

[0018]

[0019] wherein Ar2 is the same or different and is selected from substituted or unsubstituted C6-C 30 When substituted, the substituent is selected from deuterium, fluorine, phenyl, naphthyl, cyano, pyridyl, methyl;

[0020] L is selected from substituted or unsubstituted phenylene, naphthylene, fluorenylene, biphenylene, terphenylene, dibenzofuranylene, dibenzothienylene, and N-phenylcarbazolylene; when substituted, the substituent is selected from phenyl and naphthyl.

[0021] As a preferred embodiment of the present invention, Ar2 is the same or different and is selected from phenyl, naphthyl, biphenyl and terphenyl; L is selected from substituted or unsubstituted phenylene, naphthylene and biphenylene.

[0022] As a preferred embodiment of the present invention, the structure of the general formula II is specifically one of the following structures:

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029] As a preferred embodiment of the present invention, the organic electroluminescent device is used to manufacture display devices, lighting sources, signal lights, and signboards. The display devices include mobile phone displays, computer displays, television displays, smart watch displays, smart car display panels, VR or AR helmet displays.

[0030] The beneficial effects of the present invention are as follows: the triazine group is directly bonded to the adamantane fluorenyl group, and the compound protected by the present invention utilizes the electron transport characteristics of the triazine group and the rigid structure of the adamantane fluorenyl group, and at the same time designs a device structure that is used as a hole blocking layer and an electron transport layer material with a sub-aromatic group inserted between the two groups. The compound protected by the present invention not only has excellent electron transport performance and film stability, but its lower HOMO orbit can not only better prevent the hole overflow in the light-emitting layer, but also can form an ohmic contact with the electron transport layer material with a sub-aromatic group inserted between the triazine group and the adamantane fluorenyl group, thereby maximizing the optimization of the device structure and obtaining a device with excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0032] Figure 1 is the DSC spectrum of the comparative compound;

[0033] Figure 2 is the DSC spectrum of the prepared compound I-2;

[0034] Figure 3 It is a life comparison chart of device comparative example 1, comparative example 2, embodiment 1, comparative example 12, and embodiment 11. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] If the specific conditions are not specified in the embodiments, they are carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased commercially. Some reaction compounds are purchased from commodity suppliers (Zhengzhou Alpha Chemical Co., Ltd.), and some compounds that cannot be directly purchased are prepared by simple reactions of commercially available raw materials. The percentages all refer to mass percentages, and the temperatures are degrees Celsius (℃). Such method principles, operating procedures, conventional post-treatments, silica gel columns, recrystallization purification and other means are well known to synthesizers in the art, and the synthesis process can be fully realized to obtain the target product. The reactions in each preparation embodiment are generally carried out under positive pressure of nitrogen or argon.

[0037] Preparation Example

[0038] Example 1: Preparation of Compound I-2

[0039]

[0040] Synthesis of compound I-2-3: Under nitrogen protection, compound I-2-1 (3.20 g, 10 mmol), compound I-2-2 (3.81 g, 15 mmol), potassium acetate (2.45 g, 25 mmol), tris (dibenzylideneacetone) dipalladium (0) (Pd2 (dba) 3) (0.92 g, 1 mmol), and tricyclohexylphosphine (0.28 g, 1 mmol) were added to 20 ml of dioxane, and the resulting mixture was heated under reflux. After the reaction was completed, the reaction product was cooled to room temperature, dissolved in a large amount of toluene, and filtered through silica gel. The organic layer obtained therefrom was concentrated, precipitated by pouring hexane thereto, and the precipitate was filtered to obtain compound I-2-3 (3.63 g, yield 88%);

[0041] Synthesis of compound I-2: Compound I-2-4 (1.34 g, 5 mmol), compound I-2-3 (2.47 g, 6 mmol), tetrakis (triphenylphosphine) palladium (Pd (PPh3) 4) (0.12 g, 0.1 mmol), and potassium phosphate (2.12 g, 10 mmol) were added to 100 ml of tetrahydrofuran, and the resulting mixture was stirred at a temperature of 80° C. for 20 hours. After adding toluene thereto, the product obtained therefrom was filtered through silica gel and recrystallized by using toluene to obtain compound I-2 (2.07 g, yield 80%), MS: 517.36.

[0042] Example 2: Preparation of Compound I-8

[0043]

[0044] The synthesis method of compound I-8-2 is the same as the synthesis method of compound I-2-3, except that compound I-2-1 is replaced by I-8-1;

[0045] The synthesis method of compound I-8 is the same as that of compound I-2, except that compound I-8-2 replaces compound I-2-3, and I-8-3 replaces compound I-2-4, MS: 669.20.

[0046] Example 3: Preparation of Compound I-11

[0047]

[0048] The synthesis method of compound I-11-2 is the same as the synthesis method of compound I-2-3, except that compound I-2-1 is replaced by I-1-1;

[0049] The synthesis method of compound I-11 is the same as that of compound I-2, except that compound I-11-2 replaces compound I-2-3, and I-11-3 replaces compound I-2-4, MS: 669.43.

[0050] Example 4: Preparation of Compound I-26

[0051]

[0052] The synthesis method of compound I-26 is the same as that of compound I-2, except that compound I-2-4 is replaced by I-26-1, MS: 593.43.

[0053] Example 5: Preparation of Compound I-31

[0054]

[0055] The synthesis method of compound I-31 is different from that of compound I-11, except that compound I-11-3 is replaced by I-31-1, MS: 669.44.

[0056] Example 6: Preparation of Compound I-38

[0057]

[0058] The synthesis method of compound I-38 is the same as that of compound I-2, except that compound I-2-4 is replaced by I-38-1, MS: 669.41.

[0059] Example 7: Preparation of Compound I-44

[0060]

[0061] The synthesis method of compound I-44 is the same as that of compound I-8, except that compound I-8-3 is replaced by I-44-1, MS: 669.46.

[0062] Example 8: Preparation of Compound I-47

[0063]

[0064] The synthesis method of compound I-47 is the same as that of compound I-11, except that compound I-11-3 is replaced by I-47-1, MS: 643.43.

[0065] Example 9: Preparation of Compound I-50

[0066]

[0067] The synthesis method of compound I-50 is the same as that of compound I-2, except that compound I-50-1 is used to replace compound I-2-4, MS: 643.47.

[0068] Example 10: Preparation of Compound I-61

[0069]

[0070] The synthesis method of compound I-61-2 is the same as the synthesis method of compound I-2-3, except that compound I-2-1 is replaced by I-61-1;

[0071] The synthesis method of compound I-61 is the same as that of compound I-2, except that compound I-2-3 is replaced by compound I-61-2, and compound I-2-4 is replaced by I-61-3, MS: 593.39.

[0072] Example 11: Preparation of Compound II-1

[0073]

[0074] The synthesis method of compound II-1-2 is the same as that of compound I-2, except that compound II-1-1 is used to replace compound I-2-3;

[0075] The synthesis method of compound II-1 is the same as that of compound I-2, except that compound I-2-4 is replaced by II-1-2, MS: 593.39.

[0076] Example 12: Preparation of Compound II-5

[0077]

[0078] The synthesis method of compound II-5-2 is the same as that of compound I-2, except that compound II-5-1 is used to replace compound I-2-3;

[0079] The synthesis method of compound II-5 is the same as that of compound I-2, except that compound I-2-4 is replaced by II-5-2, MS: 643.48.

[0080] Example 13: Preparation of Compound II-9

[0081]

[0082] The synthesis method of compound II-9-2 is the same as that of compound I-2, except that compound II-9-1 is used to replace compound I-2-3;

[0083] The synthesis method of compound II-9 is the same as that of compound I-2, except that compound I-2-4 is replaced by II-9-2, MS: 669.44.

[0084] Example 14: Preparation of Compound II-13

[0085]

[0086] The synthesis method of compound II-13-2 is the same as that of compound I-2, except that compound II-13-1 is used to replace compound I-2-3;

[0087] The synthesis method of compound II-13 is the same as that of compound I-2, except that compound I-2-4 is replaced by II-13-2, MS: 669.42.

[0088] Example 15: Preparation of Compound II-17

[0089]

[0090] The synthesis method of compound II-17-2 is the same as that of compound I-2, except that compound II-17-1 is used to replace compound I-2-3;

[0091] The synthesis method of compound II-17 is the same as that of compound I-2, except that compound I-2-4 is replaced by II-17-2, MS: 795.48.

[0092] Example 16: Preparation of Compound II-21

[0093]

[0094] The synthesis method of compound II-21-2 is the same as that of compound I-2, except that compound II-21-1 is used to replace compound I-2-3;

[0095] The synthesis method of compound II-21 is the same as that of compound I-2, except that compound I-2-4 is replaced by II-21-2, MS: 643.42.

[0096] Example 17: Preparation of Compound II-30

[0097]

[0098] The synthesis method of compound II-30-1 is the same as that of compound I-2, except that compound I-2-3 is replaced by compound II-5-1, and compound I-2-4 is replaced by compound I-26-1;

[0099] The synthesis method of compound II-30 is the same as that of compound I-2, except that compound I-2-4 is replaced by II-30-1, MS: 719.45.

[0100] Example 18: Preparation of Compound II-80

[0101]

[0102] The synthesis method of compound II-80-1 is the same as that of compound I-2, except that compound I-2-3 is replaced by compound II-5-1, and compound I-2-4 is replaced by compound I-38-1;

[0103] The synthesis method of compound II-80 is the same as that of compound I-2, except that compound I-2-4 is replaced by II-80-1, MS: 795.49.

[0104] Example 19: Preparation of Compound II-89

[0105]

[0106] The synthesis method of compound II-89-1 is the same as that of compound I-2, except that compound I-2-3 is replaced by compound II-5-1, and compound I-2-4 is replaced by compound I-47-1;

[0107] The synthesis method of compound II-89 is the same as that of compound I-2, except that compound I-2-4 is replaced by II-89-1, and compound I-2-3 is replaced by compound I-11-2, MS: 795.24.

[0108] Example 20: Preparation of Compound II-92

[0109]

[0110] The synthesis method of compound II-92-1 is the same as that of compound I-2, except that compound I-2-3 is replaced by compound II-17-1, and compound I-2-4 is replaced by compound I-44-1;

[0111] The synthesis method of compound II-92 is the same as that of compound I-2, except that compound I-2-4 is replaced by II-92-1, MS: 947.31.

[0112] In addition, it should be noted that other compounds of the present application can be obtained by referring to the preparation methods of the above-mentioned embodiments, so they will not be listed one by one here.

[0113] Device Embodiment

[0114] Preparation of Comparative Examples 1-11 and Examples 1-10:

[0115] A glass substrate coated with ITO (indium tin oxide) as a thin film with a thickness of 1000 angstroms was placed in distilled water in which a detergent was dissolved and ultrasonically cleaned. After the ITO was cleaned for 30 minutes, ultrasonic cleaning was repeated twice with distilled water for 10 minutes, and then the substrate was ultrasonically cleaned with isopropyl alcohol, acetone and methanol solvents, dried, transferred to a plasma cleaner for cleaning for 5 minutes, and then transferred to a vacuum deposition device;

[0116] On the ITO transparent electrode, a compound [HI]: [HT] (3:97) was thermally vacuum deposited to a thickness of 100 angstroms to form a hole injection layer; a compound [HT] was vacuum deposited to 800 angstroms on the hole injection layer to form a hole transport layer; a compound [B-prime] was vacuum deposited to 50 angstroms on the hole transport layer to form an electron blocking layer (also known as a buffer layer); a compound [BH] and a compound [BD] were vacuum deposited to a thickness of 200 angstroms on the electron blocking layer at a ratio of 100:2 to form a light-emitting layer; a comparative compound and LiQ were vacuum deposited to a thickness of 300 angstroms on the light-emitting layer at a ratio of 1:1 to form an electron transport layer; yttrium (Yb) and magnesium silver (1:9) were sequentially deposited on the electron transport layer to a thickness of 10 angstroms and 1000 angstroms, respectively, to form a cathode, thereby obtaining a device of Comparative Example 1, and the vacuum degree during deposition was maintained at 1×10 -7 Up to 5×10 -8 Comparative Example 2-11 is obtained by replacing the electron transport layer in the device structure of Comparative Example 1 with a 1:1 ratio of vacuum deposition of compound I series (I-2, I-8, I-11, I-26, I-31, I-38, I-44, I-47, I-50, I-61) and LiQ to a thickness of 300 angstroms. The device of Example 1-10 is obtained by replacing the comparative compound in the device structure described above with a 1:1 ratio of vacuum deposition of the compound protected by this patent (compound II-1, II-5, II-9, II-13, II-17, II-21, II-30, II-80, II-89, II-92) and LiQ to a thickness of 300 angstroms. .

[0117] Preparation of Comparative Examples 12-21 and Examples 11-20:

[0118] The devices of Comparative Examples 11-20 are obtained by inserting a vacuum-deposited comparative compound to 50 angstroms between the light-emitting layer and the electron transport layer in the above device structure as a hole blocking layer, and then vacuum-depositing compound II series (compounds II-1, II-5, II-9, II-13, II-17, II-21, II-30, II-80, II-89, II-92) and LiQ to a thickness of 300 angstroms on the hole blocking layer at a ratio of 1:1 to form an electron transport layer; the devices of Examples 11-20 and Comparative Examples 12-2 1 Similarly, the compound I series (I-2, I-8, I-11, I-26, I-31, I-38, I-44, I-47, I-50, I-61) protected by this patent is vacuum deposited to 50 angstroms as a hole blocking layer, and then the compound II series (II-1, II-5, II-9, II-13, II-17, II-21, II-30, II-80, II-89, II-92) and LiQ are vacuum deposited on the hole blocking layer at a ratio of 1:1 to a thickness of 300 angstroms to obtain. The structures of the compounds used in the above preparation process are as follows:

[0119]

[0120] Comparative compounds

[0121] The HOMO\LUMO values ​​of the compounds in the examples were calculated using Gaussian calculation software, and the results are shown in Table 1 below;

[0122] Table 1

[0123]

[0124]

[0125] In Table 1:

[0126] Compound I Series Avg HOMO =-5.76eV, Avg LUMO = -1.86 eV;

[0127] Compound II Series Avg HOMO =-5.50eV, Avg LUMO = -1.90 eV;

[0128] (1) The main difference between the structure of the comparative compound and the structure of compound I series is that it is different from the fluorene spiro-bonded structure. The LUMO values ​​of the two are comparable and the HOMO values ​​are close, so they are selected as comparative compounds.

[0129] (2) Although compound II series has an additional L aromatic group compared to compound I series, both contain triazine groups and their LUMO energy levels are both near -1.90 eV, making them both electron transport materials with good performance. However, due to the conjugation of aromatic groups in compound II series, the molecular absorption is red-shifted, resulting in a shallower HOMO energy level than compound I series. Therefore, in organic electroluminescent devices with a hole blocking layer, compound I series is more suitable for the hole blocking layer, while compound II series is suitable for the electron transport layer.

[0130] At 10mA / cm 2 The driving voltage and current efficiency of the device embodiments and comparative examples were measured at a current density of 50 mA / cm 2 The time required for the brightness to decrease to 97% of the initial brightness (LT97) was measured at a current density of 1.5 Å. The results are shown in Tables 2 and 3 below:

[0131] Table 2

[0132]

[0133]

[0134] In Table 2: compared with Comparative Example 1, the driving voltage and current efficiency of Examples 1-10 are equivalent, and the life span is increased to a certain extent; compared with Comparative Examples 2-11, the driving voltage and current efficiency of Examples 1-10 are equivalent, and the life span is greatly improved; and the device performance of Comparative Example 1 is also improved to a certain extent compared with Comparative Examples 2-11. The compound I series provided by the present invention has the same frontier orbital energy level as the comparative compound, but has a higher Tg (see Figure 1 Tg=157.63℃、 Figure 2 Tg = 175.66 ° C), the film forming property is better, so the device life is improved. The difference in device performance between Examples 1-10 and Comparative Examples 2-11 is mainly determined by the orbital energy level. The HOMO energy level of Examples 1-10 is deeper, which can better block holes, improve the device luminescence efficiency, and thus obtain a long-life device.

[0135] Table 3

[0136]

[0137]

[0138] Compared with Table 2 and Table 3, due to the insertion of the hole blocking layer and the optimization of the device structure, the overall performance of the device has improved and the life span has increased. Figure 3 , J = 50 mA / cm 2 At this current density, the brightness drops to 970cd / m 2When the life of Example 11 is the longest, it is 166h. In Table 3: Compared with Comparative Examples 12-21, Examples 11-20 have similar driving voltage and current efficiency, and their lifespans are increased to a certain extent; similar to Table 2, this is determined by the properties of the compounds. Although the energy level values ​​of the comparative compounds and the compound I series are similar, the TG value of the comparative compounds is lower, so the film formation stability during the thermal evaporation process is not as good as that of the compound I series, and the film formation stability fundamentally affects the starting voltage, current efficiency and lifespan of the device.

[0139] In summary, the compound I series and compound II series provided by the present invention are both good electron transport layer materials. When the two are used in combination, that is, compound I series is used as a hole blocking layer and compound II series is used as an electron transport layer, and are applied to the same organic electroluminescent device, its luminescence performance can be greatly improved.

Claims

1. An adamantane fluorene compound, characterized in that: It has the following structure of general formula I: wherein Ar1 is the same or different and is selected from substituted or unsubstituted C6-C 30 when substituted, the substituent is selected from deuterium, fluorine, phenyl, naphthyl, cyano, pyridyl, and methyl.

2. The adamantane fluorene compound according to claim 1, characterized in that: The Ar1 are the same or different and are selected from phenyl, naphthyl, biphenyl and terphenyl.

3. The adamantane fluorene compound according to claim 1, characterized in that: Its structure is one of the following:

4. An organic electroluminescent device comprising a first electrode, a second electrode and an organic material layer disposed therebetween, characterized in that: The organic material layer comprises an electron transport layer and a hole blocking layer, and the electron transport layer and / or the hole blocking layer are prepared from the adamantane fluorene compound according to any one of claims 1-3.

5. The organic electroluminescent device according to claim 4, characterized in that: The hole blocking layer is prepared from the adamantane fluorene compound according to any one of claims 1 to 3, and the electron transport layer is prepared from a compound of the general formula II structure, and the structure of the general formula II is as follows: wherein Ar2 is the same or different and is selected from substituted or unsubstituted C6-C 30 When substituted, the substituent is selected from deuterium, fluorine, phenyl, naphthyl, cyano, pyridyl, methyl; L is selected from substituted or unsubstituted phenylene, naphthylene, fluorenylene, biphenylene, terphenylene, dibenzofuranylene, dibenzothienylene, and N-phenylcarbazolylene; when substituted, the substituent is selected from phenyl and naphthyl.

6. The organic electroluminescent device according to claim 5, characterized in that: The Ar2 are the same or different and are selected from phenyl, naphthyl, biphenyl and terphenyl; L is selected from substituted or unsubstituted phenylene, naphthylene and biphenylene.

7. The organic electroluminescent device according to claim 5 or 6, characterized in that: The structure of the general formula II is specifically one of the following structures:

8. The organic electroluminescent device according to any one of claims 4 to 7, characterized in that: The organic electroluminescent device is used to manufacture display devices, lighting sources, signal lights, and signboards. The display devices include mobile phone display screens, computer display screens, television display screens, smart watch display screens, smart car display panels, and VR or AR helmet display screens.

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