An organic electroluminescence device and display device

Abstract

The application belongs to the field of electroluminescence, and specifically discloses an organic electroluminescent device and a display device. The organic electroluminescent device comprises a light-emitting layer, and the light-emitting layer comprises a boron-nitrogen compound with a structural formula as shown in Formula I as a light-emitting guest material. Formula I; the application proposes a specific boron-nitrogen compound as a light-emitting guest material of a light-emitting layer of a device. On the basis of a rigid structure, the specific boron-nitrogen compound increases molecular conjugation and induces intermolecular π-π interaction, thereby producing excimer emission. This single-molecule double-emission spectrum can cover the blue light and yellow light regions, thereby solving the problems of intermediate phase separation among different light-emitting materials and poor color purity stability in the prior art. The organic electroluminescent device prepared by using the specific boron-nitrogen compound has the characteristics of high external quantum efficiency, small device efficiency roll-off and good color purity stability, and is more conducive to the further development of WOLED devices.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electroluminescence, in particular to an organic electroluminescent device and a display device. BACKGROUND

[0002] White organic electroluminescent device (WOLED: White Organic Light Emitting Diodes) is a kind of device with sandwich structure, and the organic light emitting guest material and the functional layer material are sandwiched between the metal cathode and the ITO (Indium Tin Oxide) anode. When a voltage is applied to the WOLED device, electrons are injected from the cathode, and holes are injected from the anode. Under the driving of the voltage, they move to the light emitting layer respectively, and emit photons after recombination in the light emitting layer. WOLED is considered as a promising next-generation lighting source due to its low energy consumption, high flexibility and eye protection. The guest material for light emission is the key. Phosphorescent material breaks the spin prohibition through strong SOC (spin-orbit coupling) effect, so that triplet (T1) exciton can efficiently radiate transition. It can have 100% internal quantum efficiency in principle, but on the one hand, phosphorescent material generally uses noble metals such as iridium and platinum, which is expensive, on the other hand, for deep blue phosphorescent material, there are still problems such as chemical instability and large efficiency roll-off under high current density.

[0003] In 2016, T. Hatakeyama research group reported a B-N-containing multiple resonance thermally activated delayed fluorescence (MR-TADF) material by incorporating electron-donating nitrogen and electron-deficient boron atoms into a rigid polycyclic aromatic framework, which has attracted widespread attention in the field of organic electroluminescence. MR-TADF material realizes the spatial separation of frontier molecular orbital (FMO), so as to obtain small singlet-triplet energy gap (ΔEST). This structure design enables them to utilize triplet excitons through the reverse intersystem crossing (RISC) process, thereby achieving 100% internal quantum efficiency (IQE). In addition, the inherent rigid structure of MR-TADF material can minimize vibrational coupling and vibrational relaxation, and improve the radiation transition rate (kr), thereby realizing high exciton utilization efficiency.

[0004] At present, WOLED is realized by doping red, green and blue light materials or yellow and blue light materials in the light emitting layer according to a certain proportion. However, different materials will inevitably cause phase separation, which affects the light emitting efficiency, and various materials face different aging life, so the color purity stability of WOLED device is poor, which seriously affects its further development. SUMMARY

[0005] The present application aims to improve at least one technical problem in the background art.

[0006] The first aspect of the present application provides an organic electroluminescent device, comprising a light-emitting layer, the light-emitting layer comprising a light-emitting guest material and a host material, the light-emitting guest material comprising a boron-nitrogen compound, the boron-nitrogen compound having a structural formula as shown in Formula I:

[0007]

[0008] Formula I;

[0009] wherein X is O, S or Se;

[0010] R1, R2, R3, R4, R5and R6are independently selected from one of hydrogen, C3-C12alkyl, cycloalkyl, C6-C30aryl and C6-C30heteroaryl.

[0011] In some preferred embodiments, the boron-nitrogen compound has a structure of one of compounds BN-1 to BN-126:

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027] .

[0028] In some preferred embodiments, the boron-nitrogen compound has the structure of compound BN-1.

[0029] In some preferred embodiments, the boron-nitrogen compound has the structure of compound BN-1.

[0030] .

[0031] In some preferred embodiments, the first starting material and the second starting material are one of compounds 1-10, respectively.

[0032] .

[0033] In some preferred embodiments, the third starting material is one of compounds a-1 to c-2.

[0034] .

[0035] In some preferred embodiments, the host material comprises at least one of compounds H-1 to H-205.

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059] .

[0060] In some preferred embodiments, the content of the host material is 40.0 wt%-99.0 wt%, and the content of the luminescent guest material is 1.0 wt%-60.0 wt%.

[0061] In some preferred embodiments, the organic electroluminescent device comprises successively from bottom to top: an anode, a hole injection layer, a hole transport layer, a hole transition layer, an electron blocking layer, the luminescent layer, a hole blocking layer, an electron transport layer, an electron injection layer, a cathode.

[0062] The second aspect of the present application provides a display device comprising the above-mentioned organic electroluminescent device.

[0063] The present application has the following advantages: the present application proposes a specific boron-nitrogen compound as a luminescent guest material of a luminescent layer of a device, the specific boron-nitrogen compound increases molecular conjugation on the basis of a rigid structure and induces intermolecular π-π interaction, thereby generating excimer emission, and this single-molecule double-emission spectrum can cover the blue light and yellow light regions, thereby solving the problems of intermediate phase separation and poor color purity stability in different luminescent materials in the prior art. The organic electroluminescent device prepared by using the specific boron-nitrogen compound has the characteristics of high external quantum efficiency, small device efficiency roll-off and good color purity stability, and is more conducive to the further development of WOLED devices. BRIEF DESCRIPTION OF DRAWINGS

[0064] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the following drawings of which:

[0065] Figure 1 Structure schematic diagram of the organic electroluminescent device prepared for the embodiment 1 of the present application.

[0066] Figure 2 Electroluminescence spectrum of an organic electroluminescent device prepared for Example 1 of the present application;

[0067] Figure 3 Electroluminescence spectrum of an organic electroluminescent device prepared for Comparative Example 1.

[0068] In the drawing: 1-anode; 2-hole injection layer; 3-hole transport layer; 4-hole transition layer; 5-electron blocking layer; 6-emitting layer; 7-hole blocking layer; 8-electron transport layer; 9-electron injection layer; 10-cathode. DETAILED DESCRIPTION

[0069] The concept and the resulting technical effects of the present application will be described below in conjunction with the embodiments and the drawings, so as to fully understand the purpose, scheme and effect of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0070] The molecular structures of the first raw material / second raw material compounds 1 to 10 involved in the following content are as follows:

[0071] .

[0072] The molecular structures of the third raw material compounds a-1 to c-2 involved in the following content are as follows:

[0073]

[0074] Preparation Example 1

[0075] A boron-nitrogen compound, the structure of which is shown as compound BN-1; the preparation method thereof comprises the following synthesis route:

[0076]

[0077] Specifically comprising the following steps:

[0078] (1) Synthesis of compound 1-1: The first raw material compound 1 (9.02 g, 20.0 mmol), the third raw material compound a-1 (4.74 g, 10.0 mmol) and cesium carbonate (9.75 g, 30.0 mmol) were dissolved in 100.0 mL of DMF, heated to 120°C under nitrogen and stirred for 8 hours. After the reaction was completed and cooled to room temperature, it was poured into 1 L of ice water, filtered to obtain the precipitated solid, and recrystallized with dichloromethane / methanol to obtain a white solid (compound 1-1) 12.46 g, yield 93.3%. The target product was confirmed by mass spectrometry analysis test: MALDI-MS: 1336.25 (calculated value: 1336.46).

[0079] (2) Synthesis of compound BN-1: Compound 1-1 (6.68 g, 5.0 mmol) was dissolved in 50.0 mL of tert-butyl benzene, and n-butyllithium (7.2 mL, 18 mmol, 2.5 M) was added dropwise at 40°C under nitrogen, heated to 50°C, and stirred for 2 hours. Then BBr3 (7.5 g, 30 mmol) was added dropwise at -40°C, and after stirring at room temperature for 1 hour, N,N-diisopropylethylamine (3.87 g, 30.0 mmol) was added dropwise at 0°C. The reaction system was heated to 120°C and stirred for 6 hours. After the reaction was completed, 5.0 mL of methanol and 5.0 mL of water were added to quench the reaction. The reaction system was washed with dichloromethane and water, and the organic phase was concentrated and purified by column chromatography to obtain a light yellow solid 2.61 g (compound BN-1), yield 43.6%. The target product was confirmed by mass spectrometry and elemental analysis test: MALDI-MS: 1196.57 (calculated value: 1196.61); elemental analysis: C, 84.15; H, 6.25; N, 4.51 (theoretical value: C, 84.27; H, 6.57; B, 1.81; N, 4.68; S, 2.68).

[0080] The CAS number of the used raw material compound 1 is 2407645-31-0.

[0081] The synthesis route of compound a-1 is as follows:

[0082]

[0083] The CAS number of compound 4,6-dibromo-2,7-dimethyl-dibenzo[ b, d ]thiophene is 669773-34-6, and the CAS number of compound 4-tert-butyl-2-chloroaniline is 42265-67-8.

[0084] (1) Synthesis of compound a-1-A: Compound 4,6-dibromo-2,7-dimethyl-dibenzo[b, d ] Thiophene (5.0 g, 14.6 mmol), 4-tert-butyl-2-chloroaniline (5.9 g, 32.2 mmol) and sodium tert-butoxide (4.6 g, 48.2 mmol) were dissolved in 200 mL of dry xylene, and a catalyst Pd2(dba)3(400 mg) and a ligand dppf (1.9 g) were added under nitrogen. The reaction system was heated to 120°C for 24 hours. After the reaction was completed and cooled to room temperature, the reaction solution was passed through a filter funnel. 200 mL of water and 200 mL of dichloromethane were added to the filtrate, and after extraction, the organic phase was concentrated, and column chromatography was used for purification to obtain 6.3 g of white solid (yield 78.7%). Mass spectrometry analysis was the target product MALDI-MS: 546.20 (calculated value: 546.17).

[0085] (2) Synthesis of raw material a-1: Compound a-1-A (5.0 g, 9.13 mmol) and potassium carbonate (3.8 g, 27.4 mmol) were dissolved in 100 mL of N,N-dimethylacetamide solution, and a catalyst Pd(OAc)2(103 mg) and a ligand tBu3PHBF4(250 mg) were added under nitrogen. The reaction system was heated to 150°C for 12 hours. After the reaction was completed and cooled to room temperature, the reaction system was poured into 500 mL of ice water. The precipitate was precipitated, and after filtration under reduced pressure, the filter cake was purified by column chromatography to obtain 3.6 g of white solid (yield 83.1%). Mass spectrometry analysis was the target product MALDI-MS: 474.25 (calculated value: 474.21).

[0086] Preparation Example 2

[0087] A boron-nitrogen compound having a structure as shown in compound BN-43; a preparation method thereof includes the following synthesis route:

[0088]

[0089] Specifically includes the following steps:

[0090] (1) Synthesis of compound 43-1: The first raw material compound 4 (6.82 g, 20.0 mmol), the third raw material compound b-2 (8.31 g, 24.0 mmol) and cesium carbonate (9.75 g, 30.0 mmol) were dissolved in 100.0 mL of DMF, heated to 120°C under nitrogen and stirred for 8 hours. After the reaction was completed and cooled to room temperature, it was poured into 1 L of ice water, filtered to obtain the precipitated solid, recrystallized with dichloromethane / methanol, and finally obtained as a white solid (compound 43-1) 12.30 g, yield 92.2%. The target product was confirmed by mass spectrometry analysis test: MALDI-MS: 667.01 (calculated value: 667.13).

[0091] (2) Synthesis of compound 43-2: Compound 43-1 (6.67 g, 10.0 mmol), the second raw material compound 2 (6.80 g, 15.0 mmol) and cesium carbonate (4.89 g, 15.0 mmol) were dissolved in 100.0 mL of DMF, heated to 120°C under nitrogen and stirred for 8 hours. After the reaction was completed and cooled to room temperature, it was poured into 1 L of ice water, filtered to obtain the precipitated solid, recrystallized with dichloromethane / methanol, and finally obtained as a white solid (compound 43-2) 10.06 g, yield 90.2%. The target product was confirmed by mass spectrometry analysis test: MALDI-MS: 1116.01 (calculated value: 1116.24).

[0092] (3) Synthesis of compound BN-43: Compound 43-2 (8.92 g, 8.0 mmol) was dissolved in 50.0 mL of tert-butylbenzene, and n-butyllithium (7.2 mL, 18 mmol, 2.5 M) was added dropwise at 40°C under nitrogen. It was heated to 70°C and stirred for 2 hours. Then BBr3 (7.5 g, 30 mmol) was added dropwise at -40°C, and after stirring at room temperature for 1 hour, N,N-diisopropylethylamine (3.87 g, 30.0 mmol) was added dropwise at 0°C. The reaction system was heated to 120°C and stirred for 6 hours. After the reaction was completed, 5.0 mL of methanol and water were added to the reaction system to quench the reaction. The reaction system was washed with dichloromethane and water, and the organic phase was concentrated and purified by column chromatography to obtain a light yellow solid 3.97 g (BN-43), yield 45.7%. The target product was confirmed by mass spectrometry and elemental analysis test: MALDI-MS: 960.53 (calculated value: 960.42); elemental analysis: C, 85.06; H, 5.16; N, 5.85 (theoretical value: C, 85.01; H, 5.25; B, 2.25; N, 5.83; O, 1.67).

[0093] For the starting materials used, the CAS number of compound 2 is: 2797261-68-6; the CAS number of compound 4 is: 2426679-25-4; the CAS number of compound b-2 is: 1640969-18-1.

[0094] Preparation Example 3

[0095] A boron-nitrogen compound, the structure of which is shown as compound BN-101; a method for preparing the same comprises the following synthetic route:

[0096]

[0097] Specifically comprising the following steps:

[0098] (1) Synthesis of compound 101-1: dissolve the first starting material compound 6 (8.90 g, 20.0 mmol), the third starting material compound c-1 (12.53 g, 24.0 mmol) and cesium carbonate (9.75 g, 30.0 mmol) in 100.0 mL of DMF, heat to 120°C under nitrogen and maintain stirring for 8 hours. After the reaction is completed and the temperature is cooled to room temperature, pour into 1L of ice water, and extract the precipitated solid by suction filtration, recrystallize using dichloromethane / methanol, and finally obtain white solid (compound 101-1) 12.30 g, yield 90.2%. Confirmed as the target product by mass spectrometry and elemental analysis: MALDI-MS: 946.87 (calculated value: 947.14).

[0099] (2) Synthesis of compound 101-2: dissolve compound 101-1 (9.47 g, 10.0 mmol), the second starting material compound 1 (6.77 g, 15.0 mmol) and cesium carbonate (4.89 g, 15.0 mmol) in 100.0 mL of DMF, heat to 120°C under nitrogen and maintain stirring for 8 hours. After the reaction is completed and the temperature is cooled to room temperature, pour into 1L of ice water, and extract the precipitated solid by suction filtration, recrystallize using dichloromethane / methanol, and finally obtain white solid (compound 101-2) 11.99 g, yield 87.2%. Confirmed as the target product by mass spectrometry and elemental analysis: MALDI-MS: 1378.01 (calculated value: 1378.27).

[0100] (3) Synthesis of compound BN-101: Compound 101-2 (11.0 g, 8.0 mmol) was dissolved in 50.0 mL of tert-butyl benzene, and n-butyllithium (7.2 mL, 18 mmol, 2.5 M) was added dropwise at 40°C under nitrogen. The temperature was raised to 70°C and maintained for 2 hours. Then BBr3(7.5 g, 30 mmol) was added dropwise at -40°C, and after stirring at room temperature for 1 hour, N,N-diisopropylethylamine (3.87 g, 30.0 mmol) was added dropwise at 0°C. The reaction system was heated to 120°C and stirred for 6 hours. After the reaction was completed, 5.0 mL of methanol and water were added dropwise to quench the reaction. The reaction system was washed with dichloromethane and water, and the organic phase was concentrated and purified by column chromatography to obtain 4.23 g of a light yellow solid (compound BN-101) with a yield of 42.7%. Mass spectrometry and elemental analysis confirmed that it was the target product: MALDI-MS: 1238.32 (calculated value: 1238.42); elemental analysis: C, 78.98; H, 5.08; N, 4.20 (theoretical value: C, 79.55; H, 5.21; B, 1.75; N, 4.53; S, 2.59; Se, 6.38).

[0101] For the starting materials used, compound 6 can be synthesized by the following reaction:

[0102]

[0103] The CAS number of compound 12 H-benzo[4,5]thieno[2,3-a]carbazole is 222-21-9.

[0104] The CAS number of compound 2-bromo-1,3-difluorobenzene is 64248-56-2.

[0105] Compound 12 H-benzo[4,5]thieno[2,3-a]carbazole (2.0 g, 7.3 mmol), compound 2-bromo-1,3-difluorobenzene, and cesium carbonate (3.6 g, 11.0 mmol) were dissolved in 70 mL of N,N-dimethylformamide, and heated to 150°C for 12 hours under nitrogen. After the reaction was completed and cooled to room temperature, the solvent was removed, and the solid was washed with dichloromethane and water. The organic phase was concentrated and purified by column chromatography to obtain 2.6 g of a white solid (yield 79.6%). Mass spectrometry analysis confirmed that it was the target product MALDI-MS: 447.02 (calculated value: 446.99).

[0106] The synthesis of compound c-1 is similar to that of compound a-1, and the synthesis route is as follows:

[0107]

[0108] Compound 4,6-dibromo-2-ethyl-dibenzo[ b, d ]selenophene has a CAS number of: 2982855-87-6.

[0109] The synthesis of compound c-1-A is similar to that of compound a-1-A, referring to Preparation Example 1, using 4,6-dibromo-2-ethyl-dibenzo[ b, d ]selenophene (5.7 g, 14.6 mmol) instead of compound 4,6-dibromo-2-ethyl-dibenzo[ b, d ]thiophene, and the other reactants, amounts and reaction conditions are consistent, and compound c-1-A (7.6 g, yield 87.2%) is obtained after column chromatography. Mass spectrometry analysis is the target product MALDI-MS: 594.16 (calculated value: 594.11).

[0110] The synthesis of compound c-1 is similar to that of compound a-1, referring to Preparation Example 1, using c-1-A (5.4 g, 9.13 mmol) instead of compound a-1-A, and the other reactants, amounts and reaction conditions are consistent, and compound c-1 (3.3 g, yield 69.3%) is obtained after column chromatography. Mass spectrometry analysis is the target product MALDI-MS: 522.20 (calculated value: 522.16).

[0111] According to the similar preparation method of the present preparation example and Preparation Examples 1 and 2, the remaining other compounds of compounds BN-1 to BN-126 are prepared. The corresponding first raw material, second raw material, third raw material, mass spectrometry analysis, elemental analysis and total yield of compounds BN-1 to BN-126 are shown in Table 1. The instrument used for mass spectrometry analysis is Bruker Autoflex Speed MALDI-TOF; the testing instrument used for elemental analysis is Vario Micro Cube, and the testing element type is C, H and N.

[0112] Table 1

[0113]

[0114]

[0115]

[0116]

[0117]

[0118] The molecular structures of HIL, EIL, HTL-1, HTL-2, EBL, HBL, ETL, BN-R1, H-202 involved in the following content are as follows:

[0119]

[0120]

[0121] .

[0122] Example 1

[0123] An organic electroluminescent device, a schematic diagram of the structure is shown as Figure 1 from bottom to top, including: anode, hole injection layer, hole transport layer, hole transition layer, electron blocking layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer, cathode.

[0124] The preparation process of the organic electroluminescent device includes the following steps:

[0125] (1) Substrate treatment: transparent ITO glass is used as the substrate material for device preparation. First, it is ultrasonically treated with 5% ITO cleaning solution for 30 min, then sequentially washed with distilled water (2 times), acetone (2 times), and isopropyl alcohol (2 times), and finally stored in isopropyl alcohol. Before each use, carefully wipe the surface of the ITO glass with acetone and isopropyl alcohol cotton balls, then rinse with isopropyl alcohol and dry, and then treat with plasma for 5 min for standby.

[0126] (2) Use evaporation process to prepare electroluminescent device. The evaporation process is used to prepare hole injection layer, hole transport layer, hole transition layer, electron blocking layer, light emitting layer, hole blocking layer, electron transport layer, electron injection layer and metal electrode. When the vacuum degree of the vacuum evaporation system reaches 5 × 10 -4 Pa or below, start evaporation. The deposition rate is measured by a Sanei film thickness meter. Organic electron transport layer, Liq electron injection layer and metal Al electrode are sequentially deposited on the light emitting layer using vacuum evaporation process. The deposition rate of the organic materials of the hole injection layer, hole transport layer, hole transition layer, electron blocking layer, light emitting layer, hole blocking layer and electron transport layer is 0.5 Å / s, the deposition rate of Liq is 0.1 Å / s, and the deposition rate of Al is 5 Å / s.

[0127] Wherein, HIL is used as a hole injection layer material, HTL-1 is used as a hole transport layer material, HTL-2 is used as a hole transition layer material, EBL is used as an electron blocking layer material, H-202 is used as a host material in the light-emitting layer, and the guest material is selected from BN-1 to BN-126, denoted as BN-n, the content of the guest material is 6.0wt%, 8.0wt%, 10.0wt% and 12.0wt%, HBL is used as a hole blocking layer material, ETL is used as an electron transport material, EIL (i.e. Liq) is used as an electron injection layer, and Al is used as a metal cathode. The structure of the organic electroluminescent device is: [ITO / HIL (5 nm) / HTL-1 (25 nm) / HTL-2(15 nm) / EBL(10nm) / H-202: BN-n(30 nm) / HBL (10 nm) / ETL (30 nm) / EIL (1 nm) / Al (100 nm).

[0128] Wherein, part of the compounds selected from compounds BN-1 to BN-126 are used as guest materials respectively, and the organic electroluminescent devices prepared with a content of 8.0wt% of the guest material are respectively denoted as D-1 to D-76.

[0129] Comparative Example 1

[0130] An organic electroluminescent device, which is different from Example 1, uses compound BN-R1 as a light-emitting guest material, and the content of BN-R1 is 6.0wt%, 8.0wt%, 10.0wt% and 12.0wt%.

[0131] The organic electroluminescent device with a content of 8.0wt% of BN-R1 is denoted as D-R1.

[0132] Performance test and result analysis

[0133] The current, voltage, brightness, luminescence spectrum and other characteristics of the organic electroluminescent device are tested synchronously by using a Photo Research PR655 spectral scanning luminance meter and a Keithley K 2400 digital source meter system. The performance test of the organic electroluminescent device is carried out at room temperature in an ambient atmosphere. The external quantum efficiency (EQE) of the organic electroluminescent device is calculated according to the current density, brightness and electroluminescence spectrum combined with the visual function under the condition that the luminescence is a Lambertian distribution.

[0134] The test results of the organic electroluminescent devices prepared in the examples and comparative examples are shown in Table 2.

[0135] Table 2

[0136]

[0137]

[0138]

[0139]

[0140] By Figure 2 It can be seen that BN-1 exhibits double emission peaks as a light-emitting guest. This is because the quasi-planar MR-TADF molecule adopts an ordered face-to-face stacking configuration at high concentration, inducing excimer emission, and finally realizing a single-molecule doped white OLED device based on a double TADF channel. OLEDs made with different concentrations (6.0 wt%, 8.0 wt%, 10.0 wt%, 12.0 wt%) of BN-1 show warm white light emission, accompanied by CIE coordinates moving from (0.29, 0.51) to (0.45, 0.47). The maximum external quantum efficiency of the organic electroluminescent device reaches 27.1%, and remains at 19.1% at a luminance of 1000 cd / m 2 .

[0141] Figure 3 The electroluminescent spectrum of the organic electroluminescent device prepared for Comparative Example 1, from Figure 3 it can be seen that Comparative Example 1 does not exhibit a significant excimer emission peak, and its emission peak is located at 495 nm with a half-peak width of 26 nm. Its maximum external quantum efficiency is 25.8% at a doping concentration of 8.0 wt%, and the external quantum efficiency is 12.5% at a luminance of 1000 cd / m 2 .

[0142] The above is only a preferred embodiment of the present application, and the present application is not limited to the above-described embodiments, as long as the same means achieve the technical effects of the present application, they should belong to the protection scope of the present application. The technical solutions and / or embodiments within the protection scope of the present application can have various modifications and changes.

Claims

1. An organic electroluminescent device, characterized by comprising: The organic electroluminescence device comprises a light-emitting layer, and the light-emitting layer comprises a light-emitting guest material and a host material, wherein the light-emitting guest material comprises a boron-nitrogen compound, and the boron-nitrogen compound has a structural formula as shown in formula I: Formula I; X is O, S or Se; R1, R2, R3, R4, R5 and R6 are independently selected from one of hydrogen, C3-C12 alkyl, cycloalkyl, C6-C30 aryl and C6-C30 heteroaryl.

2. The organic electroluminescent device according to claim 1, wherein The boron-nitrogen compound has a structure of one of compounds BN-1 to BN-126. 。 3. The organic electroluminescent device according to claim 2, characterized in that The boron-nitrogen compound has a structure of compound BN-1.

4. The organic electroluminescent device according to claim 1, wherein The synthesis route of the boron-nitrogen compound is shown as follows: 。 5. The organic electroluminescent device according to claim 4, characterized in that The first raw material and the second raw material are independently selected from one of compounds 1-10: 。 6. The organic electroluminescent device according to claim 4, wherein The third raw material is one of compounds a-1 to c-2: 。 7. The organic electroluminescent device according to claim 1, wherein The host material comprises at least one of compounds H-1 to H-205. 。 8. The organic electroluminescent device according to claim 1, wherein The content of the host material is 40.0 wt%-99.0 wt%, and the content of the light-emitting guest material is 1.0 wt%-60.0 wt%.

9. The organic electroluminescent device according to claim 1, wherein The organic electroluminescence device comprises, from bottom to top, an anode, a hole injection layer, a hole transport layer, a hole transition layer, an electron blocking layer, the light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode.

10. A display device, characterized by comprising: The organic electroluminescence device comprises the organic electroluminescence device according to any one of claims 1-9.

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