Boron-nitrogen compound organic luminescent material as well as preparation method and application thereof

Abstract

The invention discloses a boron-nitrogen compound organic light-emitting material as well as a preparation method and application thereof. The boron-nitrogen compound organic light-emitting material is shown in a structural general formula (1): # imgabs0 #. The material is based on a TADF mechanism, a B-N condensed ring structure can realize multiple resonance effects, generated molecules have large rigid planes, and intermolecular interaction and concentration quenching effects can be controlled, so that an efficient and stable device is realized.

Description

Technical Field

[0001] The invention belongs to the field of organic electroluminescent materials and relates to a boron nitrogen compound organic luminescent material, a preparation method thereof and an application thereof. Background Art

[0002] Recently, the development of organic electroluminescent displays as image display devices is actively being carried out. Unlike liquid crystal display devices, etc., organic electroluminescent displays are self-luminous display devices in which holes and electrons injected from the first electrode and the second electrode are recombined in the emission layer, and thus the light-emitting material including organic compounds in the emission layer emits light to realize the display of images.

[0003] Since the release of the first generation of fluorescent OLEDs, organic light-emitting diodes (OLEDs) have been comprehensively studied for decades, and in the second generation, the performance of luminescent materials doped with coordination compounds of heavy metals (iridium, platinum) has been greatly improved. Because iridium or platinum atoms have strong spin-orbit coupling effects, these compounds can make full use of the singlet (S1) and triplet (T1) excitons generated during the electroluminescence process. However, phosphorescent materials contain heavy metals, are expensive, and have poor material stability. Therefore, it is extremely important to develop an OLED device that uses cheap and stable organic small molecule materials and can achieve high-efficiency luminescence.

[0004] Thermally activated delayed fluorescence (TADF) - achieved an IQE of about 100% without using any precious metals. Unlike the localized (LE) state luminescence of traditional fluorescent molecules, TADF emission mainly originates from the transition of the ICT state, and is therefore easily affected by the vibrational and rotational motion between the donor and the acceptor, which enhances the structural relaxation of the excited state and increases the Stokes shift, resulting in a broadening of the electroluminescence (EL) peak. Although a wider spectrum is beneficial for lighting applications, it cannot meet the requirements of high color purity in the display field. The multi-resonance (MR)-induced thermally activated delayed fluorescence (TADF) material composed of electron-rich nitrogen atoms and electron-deficient boron atoms has the characteristics of narrow-band luminescence, and organic electroluminescent devices prepared from such materials have the advantage of high color purity. However, due to the limitations of the synthesis methods and purification of such materials, the types and quantities of such luminescent materials are still limited, which limits their application.

[0005] Therefore, in this field, it is very important to develop a new type of high-performance boron-nitrogen resonance heterocyclic guest material. Summary of the invention

[0006] In view of the existing problems of the above-mentioned organic materials, the present invention provides a class of BN fused ring organic light-emitting materials and their application in organic light-emitting devices. The material is based on the TADF mechanism, and the BN fused ring structure can achieve multiple resonance effects. The generated molecules have a large rigid plane, which can control the intermolecular interaction and concentration quenching effect, thereby realizing efficient and stable devices.

[0007] The present invention also provides a boron nitrogen compound organic light-emitting material, the structure of which is shown in general formula (1):

[0008]

[0009] wherein Ar is each independently selected from substituted or unsubstituted C1-C60 alkyl, substituted or unsubstituted C2-C60 alkenyl, substituted or unsubstituted C2-C60 alkynyl, substituted or unsubstituted C1-C60 alkoxy, substituted or unsubstituted C3-C10 cycloalkyl, substituted or unsubstituted C1-C10 heterocycloalkyl, substituted or unsubstituted C3-C10 cycloalkenyl, substituted or unsubstituted C1-C10 heterocycloalkenyl, substituted or unsubstituted C6-C60 aryl, substituted or unsubstituted C6-C60 aryloxy, substituted or unsubstituted C6-C60 arylthio, substituted or unsubstituted C1-C60 heteroaryl, substituted or unsubstituted non-aromatic fused polycyclic, substituted or unsubstituted non-aromatic fused heteropolycyclic.

[0010] The heteroatoms in the heterocycloalkyl, heterocycloalkenyl and heteroaryl are one or more of N, S, O, P, B and Si.

[0011] Wherein, X is N or CR1;

[0012] Wherein, Y is N or CR2;

[0013] Wherein, Z is N or CR3;

[0014] In a further technical solution, Ar is selected from the following substituted or unsubstituted groups:

[0015]

[0016] In a further technical solution, the blue light emitting material is selected from compounds having the following molecular structures 1 to 164:

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024] The second object of the present invention is to provide a method for preparing a boron nitrogen compound organic light-emitting material. The reaction process of the preparation method is shown in the following formula:

[0025]

[0026] The steps of the preparation method are as follows:

[0027] Under nitrogen protection, raw material a, raw material b, t-BuOK, t-BuLi, tBuph and DIEA were added to a three-necked flask in sequence, and after the reaction was complete, a compound having the structure of Formula 1 was obtained through post-treatment. Wherein, R, X, Y and Z have the same meanings as described above.

[0028] The post-treatment process includes adding CH2Cl2 to the reaction product to completely dissolve the product, filtering, and then concentrating the solution to obtain a crude compound. The crude product is separated by column chromatography using silica gel as a stationary phase and dichloromethane / petroleum ether as an eluent to obtain the target product.

[0029] In the actual preparation process, the structure of raw material a can be determined according to the number and position of N atoms in the corresponding N-containing five-membered ring in the target compound, and raw material a can be directly selected or prepared using existing technology; the structure of raw material b can be determined according to the substituents corresponding to Ar in the target compound, and raw material b can be directly selected or prepared using existing technology.

[0030] The third object of the present invention is to provide an application of a boron nitrogen compound organic light-emitting material, wherein the blue light-emitting material can be applied to organic solar cells, folding screens, light sensors, VR, organic transistors or inkjet printing materials.

[0031] Preferably, the organic electroluminescent device comprises a first electrode, a second electrode and a light-emitting layer therebetween, wherein the organic layer contains the above-mentioned blue light-emitting material.

[0032] Preferably, the above blue light emitting material is used as the guest of the light emitting layer in the organic electroluminescent device.

[0033] Preferably, when the organic layer in the organic electroluminescent device is the above-mentioned blue light emitting material, the molar percentage of the main material in the light emitting layer is 80%-99%, for example, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%.

[0034] Preferably, the light-emitting layer in the above-mentioned organic electroluminescent device is a multi-layer laminated structure, wherein the structure of the organic layer is from top to bottom: hole injection layer (HIL), hole transport layer (HTL), light-emitting layer (EML), electron transport layer (ETL), and electron injection layer (EIL).

[0035] Preferably, the organic electroluminescent device comprises a first electrode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer and a second electrode, wherein the light-emitting layer is an OLED light-emitting layer.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The TADF material provided by the present invention has good thermal stability, a glass transition temperature greater than 120°C, and a thermal decomposition temperature greater than 500°C. At the same time, blue light-emitting devices can be prepared by spin coating, expanding the processing methods of TADF materials. Therefore, the new TADF material provided by the present invention has broad market application prospects and is easily applicable to industrial large-scale preparation. The organic electroluminescent device formed by the compound of the present invention has a narrow half-wave width, a low driving voltage and a longer service life. DETAILED DESCRIPTION

[0038] Embodiment 1:

[0039] This embodiment relates to the preparation of the above-mentioned compound 1, which specifically includes the following process:

[0040]

[0041] In a three-necked flask, add B-1 (12.38 g, 79.8 mmol), anhydrous DMF (80 ml), t-BuOK (11.13 g, 99.31 mmol), react at room temperature for 3 hours, add A-1 (7.78 g, 40.0 mml), stir and react at 140 ° C for 24 hours, and pour the solution into ice water after the reaction is completed. Filter and dry to obtain a powder solid, and finally purify it by column chromatography with a mixed eluent of dichloromethane / petroleum ether (1:3) to obtain solid c-1 (15.86 g).

[0042] At -30°C, t-BuLi (15.3ml, 1.04M, 20mmol) and tBuph (80ml) were slowly added to compound c-1 (4.62g, 10mmol), stirred at 60°C for 3h under nitrogen, then BBr3 (1.9ml, 20mmol) was added and reacted at room temperature for 1h, and finally DIEA (2.78ml, 20mmol) was added at 0°C, the temperature was raised, and the reaction was stirred at 140°C for 8h. The mixture was extracted with dichloromethane, and the organic layer was purified by column chromatography with dichloromethane / petroleum ether (1:20) to obtain solid compound 1 (2.14g, 63%).

[0043] Mass spectrum m / z: theoretical value: 392.15; measured value: 391.84; theoretical element content C28H17BN2: C, 85.73; H, 7.14; B, 2.76; N, 7.14; measured element content C28H17BN2: C, 85.62; H, 6.68; B, 2.51; N, 6.62.

[0044] Embodiment 2:

[0045] This embodiment relates to the preparation of the above-mentioned compound 2, which specifically includes the following process:

[0046]

[0047] The preparation of compound 2 was similar to that of compound 1, except that B-2 was used instead of B-1 to obtain compound 2 (3.21 g, 68%).

[0048] Mass spectrum m / z: theoretical value: 393.14; measured value: 392.71; theoretical element content C27H16BN3: C, 82.46; H, 4.10; B, 2.75; N, 10.69; measured element content C27H16BN3: C, 81.94; H, 3.98; B, 2.62; N, 10.08.

[0049] Embodiment 3:

[0050] This embodiment relates to the preparation of the above-mentioned compound 5, which specifically includes the following process:

[0051]

[0052] The preparation of compound 5 was similar to that of compound 1, except that A-5 was used instead of A-1 to obtain compound 5 (2.89 g, 62%).

[0053] Mass spectrum m / z: theoretical value: 559.22; measured value: 559.48; theoretical element content C40H26BN3: C, 85.87; H, 4.68; B, 1.93; N, 7.51; measured element content C40H26BN3: C, 85.12; H, 4.41; B, 1.79; N, 7.32.

[0054] Embodiment 4:

[0055] This example involves the preparation of the above-mentioned compound 19, which specifically includes the following process:

[0056]

[0057] The preparation of compound 19 was similar to that of compound 1, except that A-19 was used instead of A-1, and B-19 was used instead of B-1, to obtain compound 5 (2.89 g, 67%).

[0058] Mass spectrum m / z: theoretical value: 559.20; measured value: 558.81; theoretical element content C38H22BN5: C, 81.58; H, 3.96; B, 1.93; N, 12.52; measured element content C38H22BN5: C, 80.52; H, 3.75; B, 1.76; N, 12.04.

[0059] Embodiment 5:

[0060] This example relates to the preparation of the above-mentioned compound 40, which specifically includes the following process:

[0061]

[0062] The preparation of compound 40 was similar to that of compound 1, except that A-40 was used instead of A-1, and B-40 was used instead of B-1, to obtain compound 40 (3.52 g, 58%).

[0063] Mass spectrum m / z: theoretical value: 546.20; measured value: 545.78; theoretical element content C38H23BN4: C, 83.53; H, 4.24; B, 1.98; N, 10.25; measured element content C38H23BN4: C, 83.02; H, 3.98; B, 1.86; N, 9.90.

[0064] Embodiment 6-9

[0065] Since the synthetic routes and principles of the preparation methods of other compounds having the general structural formula of Chemical Formula 1 in the content of the invention are similar to those of Examples 1-5 listed above, it is only necessary to replace the raw materials with the raw materials corresponding to the target products, and the amounts of the raw materials are adjusted according to the corresponding stoichiometric ratios to obtain the corresponding compounds, so they are not listed here in detail. The embodiments of the present invention refer to the preparation methods of Examples 1 to 5 to complete the synthesis of compounds 57, 69, 100, and 126, and their mass spectra and molecular formulas are shown in Table 1.

[0066]

[0067] Table 1

[0068] Device Examples 1-9

[0069] This embodiment provides an organic electroluminescent device, which specifically includes a first electrode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, a second electrode and the like as a structure of organic layers.

[0070] The materials of each layer are as follows:

[0071] Anode: ITO (indium tin oxide), thickness 40nm;

[0072] Hole injection layer: main material HAT-CN, thickness 8nm;

[0073] Hole transport layer: HTM1, thickness 20nm;

[0074] Electron transport layer: ET1 (50% by mole) and LiQ (50% by mole), thickness 30 nm;

[0075] Cathode: Mg / Ag (mass ratio 7:3), thickness 20nm.

[0076] The host material and guest material of the light-emitting layer are selected as shown in Table 1: the host material is the product obtained in Example 1-9; the molar percentage of the guest material is 95%, and the thickness of the light-emitting layer is 30 nm.

[0077] Table 1 Compositions of the light-emitting layers of Examples 1-9 and Comparative Examples

[0078] Serial number Light-emitting layer (30nm) Device Example 1 Compound 1 (5%): TCTA (95%) Device Example 2 Compound 2 (5%): TCTA (95%) Device Example 3 Compound 5 (5%): TCTA (95%) Device Example 4 Compound 19 (5%): TCTA (95%) Device Example 5 Compound 40 (5%): TCTA (95%) Device Example 6 Compound 57 (5%): TCTA (95%) Device Example 7 Compound 69 (5%): TCTA (95%) Device Example 8 Compound 100 (5%): TCTA (95%) Device Example 9 Compound 126 (5%): TCTA (95%) Comparative Example 1 Comparative Example 1 (5%): TCTA (95%)

[0079] In the above device embodiments 1-9 and comparative example 1, the structural formula corresponding to the abbreviation of the material is as follows:

[0080]

[0081] Performance Test:

[0082] The organic electroluminescent devices provided in the above embodiments and comparative examples were tested for luminous efficiency, and the test items and results are shown in Table 2. The device performance data were measured at a brightness of 1000 nits, and the lifespan (LT95) data were calculated at a current density of 20 mA / cm2.

[0083] Table 2 Performance test results of organic electroluminescent devices

[0084]

[0085] It can be seen from the experimental results shown in Table 2 that the organic electroluminescent device formed by the compound of the present invention has a narrow half-wave width, a low driving voltage and a longer service life.

[0086] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A boron nitrogen compound organic light-emitting material, characterized in that: The general structural formula (1) of the boron nitrogen compound is shown below: wherein Ar is each independently selected from substituted or unsubstituted C1-C60 alkyl, substituted or unsubstituted C2-C60 alkenyl, substituted or unsubstituted C2-C60 alkynyl, substituted or unsubstituted C1-C60 alkoxy, substituted or unsubstituted C3-C10 cycloalkyl, substituted or unsubstituted C1-C10 heterocycloalkyl, substituted or unsubstituted C3-C10 cycloalkenyl, substituted or unsubstituted C1-C10 heterocycloalkenyl, substituted or unsubstituted C6-C60 aryl, substituted or unsubstituted C6-C60 aryloxy, substituted or unsubstituted C6-C60 arylthio, substituted or unsubstituted C1-C60 heteroaryl, substituted or unsubstituted non-aromatic fused polycyclic, substituted or unsubstituted non-aromatic fused heteropolycyclic; The heteroatoms in the heterocycloalkyl, heterocycloalkenyl and heteroaryl are one or more of N, S, O, P, B and Si; Wherein, X is N or CR1; Wherein, Y is N or CR2; Wherein, Z is N or CR3.

2. The boron nitrogen compound organic light-emitting material according to claim 1, characterized in that: Ar is selected from the following substituted or unsubstituted groups:

3. The boron nitrogen compound organic light-emitting material according to claim 1, characterized in that: The boron nitrogen compound in the blue light emitting material is selected from compounds having the following molecular structures of 1 to 164:

4. A method for preparing a boron nitrogen compound organic light-emitting material, characterized in that: The reaction process of the preparation method is shown in the following formula: The steps of the preparation method are as follows: S1. Under nitrogen protection, raw material a, raw material b, t-BuOK, t-BuLi, tBuph and DIEA are added to a three-necked flask in sequence, and after the reaction is complete, a compound having the structure of Formula 1 is obtained by post-treatment, wherein R, X, Y and Z have the same meanings as described above; S2. The post-treatment process includes adding CH2Cl2 to the reaction product to completely dissolve the product, filtering, and then concentrating the solution to obtain a crude compound. The crude product is separated by column chromatography using silica gel as a stationary phase and dichloromethane / petroleum ether as an eluent to obtain a target product.

5. An application of a boron nitrogen compound organic light-emitting material, characterized in that: The blue light emitting material can be applied to organic solar cells, folding screens, light sensors, VR, organic transistors or inkjet printing materials.

6. The use of a boron nitrogen compound organic light-emitting material according to claim 5, characterized in that: An organic electroluminescent device is prepared, comprising a first electrode, a second electrode and a light-emitting layer therebetween, wherein the organic layer contains the above-mentioned blue light-emitting material, and preferably, the above-mentioned blue light-emitting material is used as a guest of the light-emitting layer in the organic electroluminescent device.

7. The use of a boron nitrogen compound organic light-emitting material according to claim 6, characterized in that: When the organic layer in the organic electroluminescent device is the above-mentioned blue light emitting material, the molar percentage of the main material in the light emitting layer is 80%-99%, for example, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%.

8. The use of a boron nitrogen compound organic light-emitting material according to claim 7, characterized in that: The light-emitting layer in an organic electroluminescent device is a multi-layer laminated structure, in which the structure of the organic layer from top to bottom is: hole injection layer (HIL), hole transport layer (HTL), light-emitting layer (EML), electron transport layer (ETL), and electron injection layer (EIL).

9. The use of a boron nitrogen compound organic light-emitting material according to claim 8, characterized in that The organic electroluminescent device comprises a first electrode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer and a second electrode, wherein the light-emitting layer is an OLED light-emitting layer.

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