A fluorene adamantane compound and an organic electroluminescent device thereof

Abstract

The present application provides adamantane fluorene compound and its organic electroluminescent device, triazine group is directly connected with adamantane fluorene group, the electron transport property of triazine group and the rigid structure of adamantane fluorene group are utilized, and the device structure that compound I series is designed as hole blocking layer and compound II series as electron transport layer material is inserted between the two groups is collocated.The compound I series not only inherits excellent electron transport performance and film stability, the HOMO orbit of compound I series is lower, can better prevent the hole overflow in the light emitting layer, and can form ohmic contact with the electron transport layer material of compound II series, the device structure is maximized to optimize, and excellent device performance is obtained.

Description

Technical Field

[0001] This invention belongs to the field of organic electroluminescent materials technology, and particularly relates to an adamantane fluorene compound and its organic electroluminescent device. Background Technology

[0002] The simplest organic light-emitting diode (OLED) device has a sandwich structure, consisting of two electrodes and an organic material (light-emitting layer) placed between them. To improve device efficiency and lifetime and fully utilize the performance of organic materials, OLED devices now have a multi-layer structure, introducing a hole transport layer, an electron transport layer, an electron blocking layer, and a light-emitting layer (obtained by co-evaporation of host and guest materials), with each layer performing its specific function.

[0003] As OLED applications become increasingly diversified, the requirements for their efficiency and lifespan are also becoming more varied. Besides continuously developing new materials (device components) with superior performance, optimizing the device structure is also a crucial means of improving device performance. Often, the electron transport layer in top-emitting devices only needs to both block the leakage of holes from the emitting layer and efficiently transport electrons. Adding a hole-blocking layer between the electron transport layer and the emitting layer can eliminate the hole-blocking properties of the electron transport layer material, simplifying its development to some extent, while still requiring high-performance hole-blocking layer materials that simultaneously consider both electron transport characteristics and hole-blocking performance. Therefore, hole-blocking layer materials have become a new hot topic in material development for manufacturers. Summary of the Invention

[0004] To address the problems existing in the background art, the first objective of this invention is to provide an adamantane fluorene compound, the technical solution of which is as follows:

[0005] An adamantane fluorene compound has the following structure:

[0006]

[0007] Ar1 may be the same or different, and is selected from substituted or unsubstituted C6-C. 30 The aryl group; 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 may be the same or different, and may be selected from phenyl, naphthyl, biphenyl, and terphenyl.

[0009] As a preferred embodiment of the present invention, its 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 disposed between the two, the organic material layer comprising an electron transport layer and a hole blocking layer, the electron transport layer and / or the hole blocking layer being prepared from the aforementioned adamantane fluorene compounds.

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

[0018]

[0019] Among them, Ar2 may be the same or different, and is selected from substituted or unsubstituted C6-C. 30 The aryl group; when substituted, the substituent is selected from deuterium, fluorine, phenyl, naphthyl, cyano, pyridyl, and methyl;

[0020] L is selected from substituted or unsubstituted phenylene, naphthylene, fluorene, biphenylene, terphenylene, dibenzofuranyl, dibenzothiophene, and N-phenylcarbazoylene; when substituted, the substituent is selected from phenyl or naphthyl.

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

[0022] As a preferred embodiment of the present invention, the structure of 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 signs. The display devices include mobile phone displays, computer displays, television displays, smartwatch displays, smart car display panels, and VR or AR helmet displays.

[0030] The beneficial effects of this invention are as follows: By directly linking the triazine group to the adamantane fluorene group, the compound protected by this invention utilizes the electron transport properties of the triazine group and the rigid structure of the adamantane fluorene group. Simultaneously, a device structure is designed that combines a hole-blocking layer with an electron transport layer material incorporating a deoxyrheological group inserted between these two groups. The compound protected by this invention not only inherits excellent electron transport performance and thin film stability, but its lower HOMO orbitals not only better prevent hole leakage from the light-emitting layer, but also form ohmic contacts with the electron transport layer material incorporating a deoxyrheological group between the triazine and adamantane fluorene groups, maximizing the optimization of the device structure and obtaining a device with superior performance. Attached Figure Description

[0031] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0032] Figure 1 To compare the DSC spectra of the compounds;

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

[0034] Figure 3 The graph shows a comparison of the lifetimes of devices in Comparative Example 1, Comparative Example 2, Example 1, Comparative Example 12, and Example 11. Detailed Implementation

[0035] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] Unless otherwise specified in the examples, the conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified were all commercially available products. Some reaction compounds were purchased from a supplier (Zhengzhou Alpha Chemical Co., Ltd.), and some compounds that could not be directly purchased were prepared by simple reactions from commercially available raw materials. Percentages refer to mass percentages, and temperatures are in degrees Celsius (°C). The principles, procedures, standard post-treatments, silica gel column chromatography, recrystallization purification, and other techniques of this method are well-known to those skilled in the art and can be fully implemented to obtain the target product. The reactions in each preparation example were generally carried out under positive pressure of nitrogen or argon.

[0037] Preparation Examples

[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(dibenzylacetone)dipalladium(O)(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 complete, the reaction product was cooled to room temperature, dissolved in a large amount of toluene, and filtered through silica gel. The resulting organic layer was concentrated, precipitated by pouring hexane onto it, and the precipitate was filtered to give compound I-2-3 (3.63 g, 88% yield).

[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 80 °C for 20 hours. After the addition of toluene, the product obtained was filtered through silica gel and recrystallized by toluene to give compound I-2 (2.07 g, 80% yield), 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 that of compound I-2-3, except that I-8-1 is used to replace compound I-2-1;

[0045] The synthesis method of compound I-8 is the same as that of compound I-2, except that compound I-2-3 is replaced by compound I-8-2 and compound I-2-4 is replaced by I-8-3. 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 that of compound I-2-3, except that I-1-1 is used to replace compound I-2-1.

[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 compound 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 I-26-1 is used instead of compound I-2-4. MS: 593.43.

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

[0054]

[0055] The synthesis method of compound I-31 differs from that of compound I-11 in that I-31-1 is used instead of compound I-11-3. 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 I-38-1 is used instead of compound I-2-4. 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 I-44-1 is used instead of compound I-8-3. 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 I-47-1 is used instead of compound I-11-3. 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-2-4 is replaced by compound I-50-1. 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 that of compound I-2-3, except that I-61-1 is used to replace compound I-2-1;

[0071] The synthesis method of compound I-61 is the same as that of compound I-2, except that compound I-61-2 replaces compound I-2-3, and I-61-3 replaces compound I-2-4. 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 instead of 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 instead of 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 instead of 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 instead of 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 instead of 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 II-5-1 replaces compound I-2-3 and compound I-26-1 replaces compound I-2-4.

[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 II-5-1 is used to replace compound I-2-3 and compound I-38-1 is used to replace compound I-2-4.

[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 II-5-1 replaces compound I-2-3 and compound I-47-1 replaces compound I-2-4.

[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 II-17-1 replaces compound I-2-3 and compound I-44-1 replaces compound I-2-4.

[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 in this application can be obtained by referring to the preparation methods of the examples listed above, so they will not be listed one by one here.

[0113] Device Examples

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

[0115] A glass substrate coated with a 1000 angstrom thick ITO (indium tin oxide) film was immersed in distilled water containing a cleaning agent and ultrasonically cleaned. After cleaning the ITO for 30 minutes, ultrasonic cleaning was repeated twice for 10 minutes each time with distilled water. The substrate was then ultrasonically cleaned with isopropanol, acetone, and methanol solvents, dried, and transferred to a plasma cleaner for 5 minutes before being transferred to a vacuum deposition apparatus.

[0116] On an ITO transparent electrode, a compound [HI]:[HT] (3:97) was vacuum-deposited to a thickness of 100 Å to form a hole injection layer; compound [HT] was vacuum-deposited to 800 Å on the hole injection layer to form a hole transport layer; compound [B-prime] was vacuum-deposited to 50 Å on the hole transport layer to form an electron blocking layer (also called a buffer layer); compounds [BH] and [BD] were vacuum-deposited to a thickness of 200 Å on the electron blocking layer at a ratio of 100:2 to form a light-emitting layer; a contrast compound and LiQ were vacuum-deposited to a thickness of 300 Å 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 thicknesses of 10 Å and 1000 Å, respectively, to form a cathode, thus obtaining the device of Comparative Example 1. The vacuum level during deposition was maintained at 1 × 10⁻⁶. -7 Up to 5×10 -8 Comparative Examples 2-11 were obtained by replacing the electron transport layer in the device structure of Comparative Example 1 with a 1:1 ratio vacuum-deposited compound series I (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 Å. Examples 1-10 were obtained by replacing the comparative compounds in the device structure described above with a 1:1 ratio vacuum-deposited 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 Å.

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

[0118] Comparative Examples 11-20 devices were obtained by inserting a vacuum-deposited comparative compound to a thickness of 50 Å between the light-emitting layer and the electron transport layer in the above device structure, as a hole-blocking layer. Then, compounds from the 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 were vacuum-deposited on the hole-blocking layer at a 1:1 ratio to a thickness of 300 Å to form the electron transport layer. Examples 11-20 devices and Comparative Example 12-2 Similarly, compounds of the 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 are vacuum-deposited up to 50 angstroms as a hole-blocking layer. Then, compounds of the 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 1:1 ratio to a thickness of 300 angstroms. The structures of the compounds used in the above preparation process are as follows:

[0119]

[0120] Comparative compounds

[0121] The HOMO and LUMO values ​​of each compound in the examples were calculated using Gaussian 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 = -1.86eV;

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

[0128] (1) The main difference between the structure of the comparative compound and the structure of the I series of compounds is that the structure is different from that of the fluorene screw. The LUMO values ​​of the two are similar and the HOMO values ​​are close. Therefore, it was selected as the comparative compound.

[0129] (2) Compared with the compound I series, the compound II series has added L aromatic groups. However, both contain triazine groups and the LUMO energy level is around -1.90eV. Both are high-performance electron transport materials. However, the HOMO energy level of the compound II series is shallower than that of the compound I series due to the red shift of molecular absorption caused by the conjugation of aromatic groups. Therefore, in organic electroluminescent devices with hole blocking layers, the compound I series is more suitable as hole blocking layers and the compound II series is more suitable as electron transport layers.

[0130] At 10mA / cm 2 The drive voltage and current efficiency of the device embodiments and comparative examples were determined at a current density of 50 mA / cm². 2 The time required for the brightness to decrease to 97% of the initial brightness at a given current density (LT97) was measured, and the results are shown in Tables 2 and 3 below:

[0131] Table 2

[0132]

[0133]

[0134] In Table 2: Examples 1-10 have comparable driving voltage and current efficiency to Comparative Example 1, but with a certain increase in lifetime; Examples 1-10 have comparable driving voltage and current efficiency to Comparative Examples 2-11, but with significantly improved lifetime; while Comparative Example 1 also shows a certain improvement in device performance compared to Comparative Examples 2-11. The I series compounds provided by this invention have comparable frontline orbital energy levels to the comparative compounds, but with higher Tg (see Table 2). Figure 1 Tg = 157.63℃ Figure 2 With a Tg of 175.66℃, the film-forming properties are better, thus improving the device lifetime. 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 luminous efficiency, and thus obtain a long-life device.

[0135] Table 3

[0136]

[0137]

[0138] Compared to Table 3, due to the insertion of the hole blocking layer and the optimization of the device structure, the overall device performance has improved, and the lifetime has increased. Figure 3 J = 50 mA / cm 2 At current density, the brightness drops to 970 cd / m². 2At that time, Example 11 had the longest lifetime, at 166 hours. In Table 3: Compared with Comparative Examples 12-21, Examples 11-20 had comparable driving voltage and current efficiency, but a certain increase in lifetime; similar to Table 2, this is determined by the properties of the compounds. Although the energy level values ​​of the comparative compounds are similar to those of the Compound I series, the TG value of the comparative compounds is lower, which leads to lower film formation stability during thermal evaporation than that of the Compound I series. Film formation stability fundamentally affects the device's start-up voltage, current efficiency, and lifetime.

[0139] In summary, both the Compound I series and Compound II series provided by this invention are excellent electron transport layer materials. When used together, with Compound I series as a hole blocking layer and Compound II series as an electron transport layer, in the same organic electroluminescent device, the luminescence performance can be significantly improved.

Claims

1. An organic electroluminescent device, comprising a first electrode, a second electrode, and an organic material layer disposed between the two, said organic material layer comprising an electron transport layer and a hole blocking layer, characterized in that, The hole-blocking layer is prepared from a compound of general formula I, and the electron transport layer is prepared from a compound of general formula II, the structure of which is as follows: ； Wherein, Ar1 may be the same or different, and is selected from substituted or unsubstituted phenyl, naphthyl, biphenyl, terphenyl, and when substituted, the substituent is selected from deuterium, fluorine, phenyl, naphthyl, cyano, pyridyl, methyl; Ar2 may be the same or different, and is selected from substituted or unsubstituted phenyl, naphthyl, biphenyl, terphenyl, and when substituted, the substituent is selected from deuterium, fluorine, phenyl, naphthyl, cyano, pyridyl, methyl; L is selected from substituted or unsubstituted phenylene, naphthylene, biphenylene, and when substituted, the substituent is selected from phenyl or naphthyl.

2. The organic electroluminescent device according to claim 1, characterized in that, The general formula I is selected from the following structures: ； ； ； ； ； ； 。 3. The organic electroluminescent device according to claim 1, characterized in that, The structure of general formula II is specifically one of the following structures: ； ； ； ； ； ； ； 。 4. The organic electroluminescent device according to claim 1, characterized in that, This organic electroluminescent device is used to manufacture display devices, lighting sources, signal lights, and signs. The display devices are selected from mobile phone displays, computer displays, television displays, smartwatch displays, smart car display panels, and VR or AR helmet displays.

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