Boron-nitrogen heterocyclic TADF luminescent material and application thereof

Abstract

The invention relates to a boron-nitrogen heterocyclic TADF luminescent material and application thereof, and belongs to the technical field of electronic luminescent materials. The structural formula of the boron-nitrogen heterocyclic TADF luminescent material is shown in the specification, r is a substituted or unsubstituted C1-C30 alkane chain, a C1-C30 aryl group or a C1-C30 heteroaryl group, a substituent group of the substituted or unsubstituted alkane chain is selected from hydrogen, deuterium, the C1-C30 alkane chain, the C1-C30 aryl group and the C1-C30 heteroaryl group, and heteroatoms in the heteroaryl group are selected from any one or more of N, O and S. The boron-nitrogen heterocyclic ring TADF luminescent material has good molecular stability when applied to organic electroluminescent devices, the prepared OLED device has excellent photoelectric properties, high luminous efficiency and low driving voltage, the service life of the device can be prolonged, and the boron-nitrogen heterocyclic ring TADF luminescent material has good application prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of boron-nitrogen heterocyclic TADF light-emitting material and its application, belong to electronic luminescent material technical field. BACKGROUND

[0002] Organic electroluminescent device (Organic Light Emitting Diode, OLED for short), compared with liquid crystal display, has the advantages of high brightness, thin volume, rapid response, stable performance, high contrast, wide viewing angle, full color, it is relatively easy to prepare large-area flexible screen, etc., it is expected to replace the existing LCD display and fluorescent lamp lighting, and the application prospect is very superior.

[0003] The basic structure of OLED device is similar to "sandwich", including an indium tin oxide (ITO) connected with power positive electrode, a metal cathode, and the functional structure layer sandwiched between the positive electrode and the cathode. Compared with the basic structure, the hole transport layer (HTL), the light-emitting layer (EML) and the electron transport layer (ETL) will be included in the structure layer. When the power supply reaches the appropriate voltage, the positive hole from the hole transport layer and the negative charge from the electron transport layer will combine in the light-emitting layer. The migration of charge carriers in the corresponding organic layer eventually reaches the light-emitting layer and recombines to form an exciton. When the exciton returns to the ground state by radiative decay, a photon is emitted. The color of the light emitted depends mainly on the band gap width of the light-emitting material. Electroluminescent materials play a crucial role in OLED display technology.

[0004] However, the traditional OLED material is limited by internal quantum efficiency, and although the internal quantum efficiency of phosphorescent emitter based on heavy metal complex is significantly improved, there are problems of high cost and environmental unfriendliness. Therefore, it is urgent to develop new organic emitters to achieve efficient utilization of triplet excitons. TADF (thermally activated delayed fluorescence) materials emerge as the times require. TADF (thermally activated delayed fluorescence) materials are considered as the third generation of light-emitting materials due to their high fluorescence efficiency. Therefore, it is still an important task for researchers to design a TADF light-emitting material with long light-emitting life and high color purity. SUMMARY

[0005] The present application provides a kind of boron-nitrogen heterocyclic TADF light-emitting material and its application to solve the problems in the prior art, the boron-nitrogen heterocyclic TADF light-emitting material has superior TADF photoelectric performance when applied in organic electroluminescent device, has higher luminous efficiency, lower driving voltage and higher external quantum efficiency, can prolong the service life of device, and has superior color purity.

[0006] The technical scheme for solving the above technical problems is as follows: a boron-nitrogen heterocyclic TADF light-emitting material, the structure formula of the boron-nitrogen heterocyclic TADF light-emitting material is as follows: ; R is a substituted or unsubstituted C1-C30 alkyl chain, a C1-C30 aryl group or a C1-C30 heteroaryl group, and the substituents of the substituted or unsubstituted group are selected from hydrogen, deuterium, a C1-C30 alkyl chain, a C1-C30 aryl group, a C1-C30 heteroaryl group, and the heteroatoms in the heteroaryl group are selected from any one or several of N, O and S.

[0007] Further, the R is any one of a biphenyl group, a deuterated biphenyl group, a naphthyl group, a phenanthryl group, a pyrenyl group, a chrysenyl group, a benzochrysenyl group, a fluorenyl group, a triphenylenyl group, a furanyl group, a carbazolyl group, an oxazolyl group, a thienyl group, a thiazolyl group and a triazinyl group.

[0008] Further, the R is any one of the following structural formulae: .

[0009] Further, the boron-nitrogen heterocyclic TADF light-emitting material is selected from any one of the following structures: .

[0010] The application of the boron-nitrogen heterocyclic TADF light-emitting material, the boron-nitrogen heterocyclic TADF light-emitting material is applied to an organic electroluminescent device.

[0011] Further, the boron-nitrogen heterocyclic TADF light-emitting material is applied to an organic layer of an organic electroluminescent device.

[0012] Further, the boron-nitrogen heterocyclic TADF light-emitting material is applied to an organic electroluminescent device.

[0013] Further, the boron-nitrogen heterocyclic TADF light-emitting material is applied to an organic electroluminescent device.

[0014] Further, the organic electroluminescent device comprises a substrate layer, an anode electrode layer, 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 cathode reflection electrode layer.

[0015] Further, the boron-nitrogen heterocyclic TADF light-emitting material is applied to a light-emitting layer or an electron transport layer of an organic electroluminescent device, and the organic electroluminescent device has a blue light characteristic.

[0016] The present application has the following advantages: The boron-nitrogen heterocyclic light-emitting material has the advantages of high light-emitting efficiency, high external quantum efficiency, low driving voltage, long service life, etc. when applied to an organic electroluminescent device.

[0017] Specifically, the boron-nitrogen heterocyclic light-emitting material embeds a carbazole ring in a B / N light-emitting core to prepare a series of high-efficiency, narrow-band TADF materials. The opposite resonance effect generated by B / N makes the HOMO / LUMO distribution of the molecule discrete, thereby realizing a small singlet-triplet energy gap (ΔE ST ), thereby having superior TADF photoelectric performance, high light-emitting efficiency, low driving voltage, and high external quantum efficiency, prolonging the service life of the device, and having superior color purity, which can meet the requirements of device manufacturers.

[0018] The "heavy atom effect" of the deuterated compound of the boron-nitrogen heterocyclic light-emitting material can improve the quantum efficiency, prolong the service life and stability of the light-emitting device material. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The figure is a schematic structural diagram of the organic electroluminescent device described in the examples. In the figure, 1 is a transparent substrate layer, 2 is a transparent anode electrode layer, 3 is a hole injection layer, 4 is a hole transport layer, 5 is an electron blocking layer, 6 is a light-emitting layer, 7 is a hole blocking layer, 8 is an electron transport layer, 9 is an electron injection layer, and 10 is a cathode reflection electrode layer. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below. In the following description, a large number of specific details are set forth in order to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the scope of the present application, therefore the present application is not limited by the specific examples disclosed below.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing the specific embodiments and are not intended to limit the present application.

[0022] I. Preparation Examples Preparation of common intermediate compound D: ; The preparation of compound D comprises the following steps: (1) Synthesis of compound A: under inert gas protection, the tetrahydrofuran solution of raw material B was added dropwise to the mixed solution containing raw material A, potassium hydroxide, water, catalyst (palladium acetate), ligand (X-Phos (CAS: 564483-18-7)) at 70-75°C, the molar ratio of raw material A, raw material B, potassium hydroxide, palladium acetate, ligand was 1.0:4.0:4.0 (50% aqueous solution):0.01:0.02 eq, and the reaction was kept at 70-75°C. After the reaction was completed, water washing, column chromatography and recrystallization were carried out to obtain light yellow solid compound A with a total yield of 63% and GC of 98.5%. GC-MS: Theoretical value: 425.20, actual value: 424.2.

[0023] The nuclear magnetic hydrogen spectrum data of compound A is as follows: 1 H-NMR (500 MHz, Chloroform-d) δ 7.58 (d, J = 1.5 Hz, 2H), 7.51 (t, J= 1.5 Hz, 1H), 7.38 – 7.31 (m, 4H), 7.00 (s, 2H), 1.33 (s, 18H). (2) Synthesis of compound B: under inert gas protection, the toluene solution of compound A and p-chlorobromobenzene was added dropwise to the toluene solution containing sodium tert-butoxide, catalyst (tris(dibenzylideneacetone)dipalladium), ligand (X-Phos (CAS: 564483-18-7)) at 105-110°C, the molar ratio of compound A, p-chlorobromobenzene, sodium tert-butoxide, catalyst, ligand was 1:2.5:3.0:0.01:0.02 eq; the reaction was kept at 105-110°C. After the reaction was completed, hydrolysis, water washing, column chromatography and recrystallization were carried out to obtain gray solid compound B with a total yield of 76.0% and HPLC of 99.5%. HPLC-MS: Theoretical value: 646.28, actual value: 644.2.

[0024] The nuclear magnetic hydrogen spectrum data of compound B is as follows: 1H-NMR (500 MHz, Chloroform-d) δ 7.57 (t, J = 1.5 Hz, 1H), 7.50 –7.45 (m, 2H), 7.40 (d, J = 1.4 Hz, 2H), 7.37 – 7.32 (m, 2H), 7.18 (s, 8H),1.28 (s, 18H). (3) Synthesis of compound C: under inert gas protection, compound B, potassium hydroxide, quinoline mixture was heated, the molar ratio of compound B to potassium hydroxide was 1:40 eq, and the reaction was complete at 215.0°C. After treatment, yellow solid compound G was obtained by extraction, water washing, column chromatography and recrystallization, the total yield was 53.0%, HPLC: 99.0%. HPLC-MS: Theoretical value: 573.37, found value: 572.2.

[0025] The nuclear magnetic hydrogen spectrum data of compound C is: 1 H-NMR (500 MHz, Chloroform-d) δ 8.00 – 7.95 (m, 2H), 7.91 (dd, J =13.5, 1.5 Hz, 2H), 7.83 – 7.78 (m, 2H), 7.55 (t, J = 1.5 Hz, 1H), 7.48(d, J =7.5 Hz, 2H), 7.28 – 7.20 (m, 4H), 1.29 (s, 18H). (4) Synthesis of compound D: under inert gas protection, a mixed solution containing compound C, pinacol diboronic acid, potassium acetate, xylene, catalyst (tris(dibenzylideneacetone) dipalladium), ligand (tricyclohexylphosphine) was heated, the molar ratio of compound C, pinacol diboronic acid, potassium acetate, catalyst, ligand was 1:1.2:3:0.01:0.02 eq, and the reaction was complete after 12 h of incubation at 130-135°C. After treatment, white solid D was obtained by column chromatography and recrystallization, the total yield was 78.0%, HPLC: 99.5%. LC-MS: Theoretical value: 756.41, found value: 756.4.

[0026] The nuclear magnetic hydrogen spectrum data of compound D is: 1H-NMR (500 MHz, Chloroform-d) δ 7.90 - 7.82 (m, 4H), 7.65 (dd, J = 7.4, 1.5 Hz, 2H), 7.58 (d, J = 1.6 Hz, 2H), 7.53 (t, J = 1.5 Hz, 1H), 7.44 (d, J = 7.7 Hz, 2H), 7.23 (d, J = 1.4 Hz, 2H), 1.31 (s, 18H), 1.24 (s, 24H). Example 1 Synthesis of compound (3): ; Under inert gas protection, 30.0 g (0.04 mol) of compound D, 18.0 g (0.087 mol) of intermediate 3, 22.0 g (0.159 mol) of potassium carbonate, 300 mL of dioxane, 51.3 mL of water, 0.09 g of palladium acetate, and 0.38 g of X-Phos (CAS: 564483-18-7) were weighed into a 1 L three-necked flask, stirred, and heated to 85-90°C, and kept at this temperature for 10 h. HPLC: 97.6%. After water boiling, column chromatography, and recrystallization, 25.8 g of white solid compound (3) was obtained, with a total yield of 86.0%, and HPLC: 99.95%. HPLC-MS: Theoretical value: 756.80, found value: 756.4.

[0027] The nuclear magnetic resonance hydrogen spectrum data of compound (3) are as follows: 1H NMR (500 MHz, Chloroform-d) δ 9.17 (d, J = 1.4 Hz, 2H), 7.97 - 7.89 (m, 6H), 7.87 (dt, J = 7.5, 1.6 Hz, 2H), 7.84 - 7.79 (m, 2H), 7.72 (dd, J = 7.5, 1.5 Hz, 2H), 7.59 - 7.42 (m, 9H), 7.32 (d, J = 7.5 Hz, 2H), 7.23 (d, J = 1.4 Hz, 2H), 1.31 (s, 18H). Example 2 Synthesis of compound (12): ; Under inert gas protection, 30.0 g (0.04 mol) of compound D, 22.9 g (0.087 mol) of intermediate 12, 8.9 g (0.159 mol) of potassium hydroxide, 300 mL of dioxane, 20.8 mL of water, 0.09 g of palladium acetate, and 0.38 g of X-Phos (CAS: 564483-18-7) were placed in a 1 L three-necked flask, stirred, and heated to 85-90°C, and reacted for 15 h. HPLC: 95.4%. After water boiling, column chromatography, and recrystallization, 24.7 g of white solid compound (12) was obtained, with a total yield of 65%, and HPLC: 99.97%. HPLC-MS: Theoretical value: 957.04, found value: 956.4.

[0028] The nuclear magnetic hydrogen spectrum data of compound (12) are as follows: 1 H NMR (500 MHz, Chloroform-d) δ 9.51 (d, J = 1.8 Hz, 2H), 9.18 –9.14 (m, 2H), 8.76 (d, J = 7.4 Hz, 2H), 8.37 – 8.32 (m, 2H), 8.04 (dd, J =7.4, 1.5 Hz, 2H), 7.95 – 7.88 (m, 4H), 7.87 – 7.79 (m, 4H), 7.76 (dd, J =7.5, 1.5 Hz, 2H), 7.71 – 7.62 (m, 10H), 7.60 –7.50 (m, 3H), 7.20 (d, J = 1.4Hz, 2H), 1.31 (s, 18H). Example 3 Synthesis of compound (25): ; Under inert gas protection, 30.0 g (0.04 mol) of compound D, 20.6 g (0.087 mol) of intermediate 25, 22.0 g (0.159 mol) of potassium carbonate, 300 mL of dioxane, 51.3 mL of water, 0.09 g of palladium acetate, and 0.38 g of X-Phos (CAS: 564483-18-7) were placed in a 1 L three-necked flask, stirred, and heated to 85-90°C, and reacted for 10 h. HPLC: 98.0%. After water boiling, column chromatography, and recrystallization, 27.1 g of white solid compound (25) was obtained, with a total yield of 81.7%, and HPLC: 99.96%. HPLC-MS: Theoretical value: 836.84, found value: 836.4.

[0029] The nuclear magnetic hydrogen spectrum data of compound (25) are as follows: 1 H NMR (500 MHz, Chloroform-d) δ 9.16 (d, J = 1.6 Hz, 2H), 8.02 (ddd,J = 11.7, 7.4, 1.4 Hz, 4H), 7.98 – 7.93 (m, 2H), 7.85 – 7.79 (m, 4H), 7.66(dd, J = 7.5, 1.5 Hz, 2H), 7.58 (dd,J = 7.5, 1.6 Hz, 2H), 7.52 (t, J = 1.5Hz, 1H), 7.50 – 7.33 (m, 8H), 7.20 (d, J = 1.4 Hz, 2H), 1.31 (s, 18H). Example 4 Synthesis of compound (32): ; Under inert gas protection, 30.0 g (0.04 mol) of compound D, 34.2 g (0.087 mol) of intermediate 32, 22.0 g (0.159 mol) of potassium carbonate, 300 mL of dioxane, 51.3 mL of water, 0.09 g of palladium acetate, and 0.38 g of X-Phos (CAS: 564483-18-7) were weighed into a 1 L three-necked flask, stirred, and heated to 85-90°C, and reacted for 12 h. HPLC: 96.2%. After water boiling, column chromatography, and recrystallization, 28.3 g of white solid compound (32) was obtained, with a total yield of 72.1%, and HPLC: 99.98%. HPLC-MS: Theoretical value: 989.04, found value: 988.4.

[0030] The nuclear magnetic resonance hydrogen spectrum data of compound (32) are as follows: 1 H NMR (500 MHz, Chloroform-d) δ 9.21 (d, J = 1.4 Hz, 2H), 7.98 –7.93 (m, 2H), 7.82 (ddd, J = 10.3, 7.2, 1.3 Hz, 4H),7.62 – 7.56 (m, 4H), 7.52(t, J = 1.5 Hz, 1H), 7.49 – 7.31 (m, 20H), 7.20 (d, J = 1.4 Hz, 2H), 1.31 (s,18H). Example 5 Synthesis of compound (36): ; Under inert gas protection, 30.0 g (0.04 mol) of compound D, 28.1 g (0.087 mol) of intermediate 36, 22.0 g (0.159 mol) of potassium carbonate, 300 mL of dioxane, 51.3 mL of water, 0.09 g of palladium acetate, and 0.38 g of X-Phos (CAS: 564483-18-7) were weighed and placed in a 1 L three-necked flask. The mixture was stirred and heated to 85-90 °C and maintained at this temperature for 8 h. HPLC yield: 97.8%. After boiling in water, column chromatography, and recrystallization, 31.5 g of a white solid compound (36) was obtained. Overall yield: 80.5%, HPLC yield: 99.98%. HPLC-MS: Theoretical value: 987.07, Measured value: 986.5.

[0031] The 1H NMR spectrum data of compound (36) are as follows: 1 H NMR (500 MHz, Chloroform-d) δ 9.13 (d, J = 1.4 Hz, 2H), 8.15 –8.10 (m, 2H), 8.03 (d, J = 7.5 Hz, 2H), 7.96 – 7.91 (m, 2H), 7.87 – 7.79 (m,4H), 7.64 – 7.58 (m, 5H), 7.57 (d, J = 1.5 Hz, 1H), 7.55 – 7.47 (m, 5H), 7.45(dq, J = 7.9, 1.5 Hz, 4H), 7.35 – 7.22 (m, 8H), 7.20 (d, J = 1.4 Hz, 2H),1.31 (s, 18H). Example 6 Synthesis of compound (40): ; Under inert gas protection, 30.0 g (0.04 mol) of compound D, 34.75 g (0.087 mol) of intermediate 40, 22.0 g (0.159 mol) of potassium carbonate, 300 mL of dioxane, 51.3 mL of water, 0.09 g of palladium acetate, and 0.38 g of X-Phos (CAS: 564483-18-7) were weighed and placed in a 1 L three-necked flask. The mixture was stirred and heated to 85-90 °C, and the reaction was maintained at this temperature for 12 h. HPLC yield: 95.6%. After boiling in water, column chromatography, and recrystallization, 34.1 g of a white solid compound (40) was obtained. The overall yield was 75.5%, and the HPLC yield was 99.96%. HPLC-MS: theoretical value: 1139.27, measured value: 1138.5.

[0032] The nuclear magnetic hydrogen spectrum data of compound (40) is: 1 H NMR (500 MHz, Chloroform-d) δ 9.13 (d, J = 1.4 Hz, 2H), 8.14 (dd,J = 7.3, 1.6 Hz, 2H), 8.02 (d, J = 7.6 Hz, 2H), 7.96 –7.91 (m, 2H), 7.88 (q,J = 0.9 Hz, 4H), 7.84 – 7.79 (m, 2H), 7.67 – 7.55 (m, 10H), 7.52 (t, J = 1.5Hz, 1H), 7.49– 7.18 (m, 20H), 1.31 (s, 18H). Example 7 Synthesis of compound (47): ; Under inert gas protection, 30.0 g (0.04 mol) of compound D, 20.0 g (0.087 mol) of intermediate 47, 8.9 g (0.159 mol) of potassium hydroxide, 300 mL of dioxane, 20.8 mL of water, 0.09 g of palladium acetate, and 0.38 g of X-Phos (CAS: 564483-18-7) were weighed into a 1 L three-necked flask, stirred, and heated to 85-90°C, and kept for 20 h. HPLC: 94.7%. After water boiling, column chromatography, and recrystallization, 22.9 g of white solid compound (47) was obtained, with a total yield of 64.8%, and HPLC: 99.97%. HPLC-MS: Theoretical value: 890.89, found value: 890.4.

[0033] The nuclear magnetic hydrogen spectrum data of compound (47) is: 1 H NMR (500 MHz, Chloroform-d) δ 9.18 (q, J = 0.9 Hz, 2H), 8.14 –8.08 (m, 4H), 8.00 – 7.95 (m, 2H), 7.84 – 7.79 (m, 2H), 7.75 (d, J = 0.9 Hz,4H), 7.63 (dd, J = 7.4, 1.6 Hz, 2H), 7.58 (dd, J = 7.5, 1.5 Hz, 2H), 7.52 (t,J = 1.5 Hz, 1H), 7.48 – 7.37 (m, 8H), 7.20 (d, J = 1.4 Hz, 2H), 1.31 (s,18H).

[0034] Example 8 Synthesis of compound (56): ; Under inert gas protection, 30.0 g (0.04 mol) of compound D, 31.2 g (0.087 mol) of intermediate 56, 22.0 g (0.159 mol) of potassium carbonate, 300 mL of dioxane, 51.3 mL of water, 0.09 g of palladium acetate, and 0.38 g of X-Phos (CAS: 564483-18-7) were weighed into a 1 L three-necked flask, stirred, and heated to 85-90°C, and kept at this temperature for 15 h. HPLC: 92.8%. After water boiling, column chromatography, and recrystallization, 29.9 g of white solid compound (56) was obtained, with a total yield of 65.7%, and HPLC: 99.98%. HPLC-MS: Theoretical value: 1147.37, actual value: 1146.7.

[0035] The nuclear magnetic hydrogen spectrum data of compound (56) are as follows: 1 H NMR (500 MHz, Chloroform-d) δ 9.35 (d, J = 1.4 Hz, 1H), 8.67 (d, J= 1.8 Hz, 1H), 8.13 (dd, J = 7.4, 1.4 Hz, 2H), 8.06 (d, J = 7.4 Hz, 1H), 8.04– 7.95 (m, 3H), 7.84 –7.79 (m, 2H), 7.30 (t, J = 1.5 Hz, 1H), 7.20 (d, J =1.4 Hz, 2H), 1.31 (s, 18H). The synthesis methods of other compounds included in the present application are the same as or similar to the specific embodiment cases, and will not be listed one by one. The mass-to-charge ratios of the synthesized compounds are shown in Table 1 and Table 2 below.

[0036] Table 1 Mass-to-charge ratios of compound (1)-compound (28)

[0037] Table 2 Mass-to-charge ratios of compound (29)-compound (56)

[0039] II. Preparation and evaluation of organic electroluminescent devices The application effects of the OLED materials synthesized in the application in devices are illustrated in detail by the following application examples 1-11 and comparative examples 1-4, and the specific compounds are shown in the following structural formulas: .

[0040] Comparative example 1 The structure of the organic electroluminescent device is shown in Figure 1 The transparent anode electrode layer 2 (209 nm thick, indium tin oxide) with a transparent substrate layer 1 was treated as follows: the glass transparent substrate layer 1 was washed, i.e. sequentially washed with alkali, deionized water, acetone ultrasonic, ethanol ultrasonic, ultrapure water, dried, and then the transparent anode electrode layer 2 was washed with UV-ozone to ensure that the organic residues on the surface of the transparent anode electrode layer 2 were removed. After the above treatment, the hole injection layer 3 was deposited on the transparent anode electrode layer 2, and a material of structural formula one was deposited by using a vacuum deposition device (deposition conditions: molybdenum crucible, deposition rate 0.1 nm / s, vacuum degree 4.0*10 -5 Pa), and the film thickness was 57 nm. This organic material was used as the hole injection layer 3. After the hole injection layer 3, a material of structural formula two was deposited as the hole transport layer 4 with a thickness of 23 nm, and then a material of structural formula three was deposited as the electron blocking layer 5 with a thickness of 19 nm.

[0041] After the deposition of the electron blocking layer 5 was completed, a material of structural formula four and Ir(PPy)3 were mixed as doping materials according to a doping weight ratio of 94:6, and then deposited on the electron blocking layer 5 (deposition conditions: molybdenum crucible, deposition rate 0.1 nm / s, vacuum degree 4.0*10 -5 Pa) to obtain the light-emitting layer 6, and the film thickness of the light-emitting layer 6 was 32 nm.

[0042] The hole blocking layer 7 was prepared after the light-emitting layer 6, and a material of the hole blocking layer 7 (a material of structural formula five) was vacuum deposited on the light-emitting layer 6 (deposition conditions: molybdenum crucible, deposition rate 0.1 nm / s, vacuum degree 4.0*10-5Pa), and the vacuum deposition film thickness of the material was 19 nm. After the deposition was completed, a material of structural formula six was deposited to obtain the electron transport layer 8, and the deposition film thickness was 79 nm. The electron injection layer 9 was prepared on the electron transport layer 8 by using a vacuum deposition device to obtain a 0.8 nm thick lithium fluoride (LiF) layer as the electron injection layer 9.

[0043] A cathode reflective electrode layer 10 was formed on the electron injection layer 9 by vacuum deposition. The cathode reflective electrode layer 10 was an aluminum (Al) layer having a film thickness of 146 nm.

[0044] After the organic electroluminescent device was completed as described above, the anode and the cathode were connected by a publicly known driving circuit, and the luminous efficiency, the emission spectrum, and the current-voltage characteristics of the device were measured.

[0045] Comparative Example 2 An organic electroluminescent device was produced in the same manner as in Comparative Example 1, except that the host light-emitting material (Formula Four) used in the light-emitting layer 6 of the organic electroluminescent device was changed to a compound of Formula Five.

[0046] Comparative Example 3 An organic electroluminescent device was produced in the same manner as in Comparative Example 1, except that the host light-emitting material (Formula Four) used in the light-emitting layer 6 of the organic electroluminescent device was changed to a compound of Formula Seven.

[0047] Comparative Example 4 An organic electroluminescent device was produced in the same manner as in Comparative Example 1, except that the host light-emitting material (Formula Four) used in the light-emitting layer 6 of the organic electroluminescent device was changed to a compound of Formula Eight.

[0048] Application Example 1 An organic electroluminescent device was produced in the same manner as in Comparative Example 1, except that the host light-emitting material (Formula Four) used in the light-emitting layer 6 of the organic electroluminescent device was changed to Compound (3).

[0049] Application Example 2 An organic electroluminescent device was produced in the same manner as in Comparative Example 1, except that the host light-emitting material (Formula Four) used in the light-emitting layer 6 of the organic electroluminescent device was changed to Compound (12).

[0050] Application Example 3 An organic electroluminescent device was produced in the same manner as in Comparative Example 1, except that the host light-emitting material (Formula Four) used in the light-emitting layer 6 of the organic electroluminescent device was changed to Compound (25).

[0051] Application Example 4 An organic electroluminescent device was produced in the same manner as in Comparative Example 1, except that the host light-emitting material (Formula Four) used in the light-emitting layer 6 of the organic electroluminescent device was changed to Compound (32).

[0052] Application Example 5 An organic electroluminescent device was produced in the same manner as in Comparative Example 1, except that the host material (Formula Four) used in the light-emitting layer 6 of the organic electroluminescent device was changed to compound (36).

[0053] Example 6 An organic electroluminescent device was produced in the same manner as in Comparative Example 1, except that the host material (Formula Four) used in the light-emitting layer 6 of the organic electroluminescent device was changed to compound (40).

[0054] Example 7 An organic electroluminescent device was produced in the same manner as in Comparative Example 1, except that the host material (Formula Four) used in the light-emitting layer 6 of the organic electroluminescent device was changed to compound (47).

[0055] Example 8 An organic electroluminescent device was produced in the same manner as in Comparative Example 1, except that the host material (Formula Four) used in the light-emitting layer 6 of the organic electroluminescent device was changed to compound (56).

[0056] Example 9 An organic electroluminescent device was produced in the same manner as in Comparative Example 1, except that the Formula Six used in the electron-transporting layer 8 of the organic electroluminescent device was changed to compound (12).

[0057] Example 10 An organic electroluminescent device was produced in the same manner as in Comparative Example 1, except that the Formula Six used in the electron-transporting layer 8 of the organic electroluminescent device was changed to compound (32).

[0058] Example 11 An organic electroluminescent device was produced in the same manner as in Comparative Example 1, except that the Formula Six used in the electron-transporting layer 8 of the organic electroluminescent device was changed to compound (56).

[0059] The organic electroluminescent devices produced in Examples 1-11 and Comparative Examples 1-4 were tested at the same luminance (1000 cd / m 2 ), the same external ambient temperature (25.0°C), and the same humidity (40.0%) and the results are shown in Table 3.

[0060] Table 3 Test Results

[0061] According to the comparison of the data in Table 3, it can be seen that the boron-nitrogen heterocyclic TADF light-emitting material has good molecular stability when applied to an organic electroluminescent device, and the organic electroluminescent device prepared by using the boron-nitrogen heterocyclic TADF light-emitting material as an OLED light-emitting material has more obvious advantages in current efficiency, driving voltage, lifetime, external quantum efficiency and other performances. Therefore, the compound prepared by using the application has great commercial value, wide market and industrialization prospect when applied to an organic electroluminescent device.

[0062] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the present disclosure.

[0063] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of the patent protection of the present application should be subject to the appended claims.

Claims

1. A boron-nitrogen heterocyclic TADF light-emitting material characterized by The boron-nitrogen heterocyclic TADF light-emitting material has the following structural formula: ； R is a substituted or unsubstituted C1-C30 alkyl chain, C1-C30 aryl or C1-C30 heteroaryl, and the substituents of the substituted or unsubstituted groups are selected from hydrogen, deuterium, C1-C30 alkyl chain, C1-C30 aryl, C1-C30 heteroaryl, and the heteroatoms in the heteroaryl are selected from any one or several of N, O and S. 2.The boron-nitrogen heterocyclic TADF light-emitting material according to claim 1, characterized in that, The R is any one of biphenyl, deuterated biphenyl, naphthyl, phenanthryl, pyrenyl, chrysenyl, benzochrysenyl, fluorenyl, triphenylenyl, furanyl, carbazolyl, oxazolyl, thienyl, thiazolyl and triazinyl. 3.The boron-nitrogen heterocyclic TADF light-emitting material according to claim 1, characterized in that, The R is any one of the following structural formulae: 。 4.The boron-nitrogen heterocyclic TADF light-emitting material according to claim 1, characterized in that, The boron-nitrogen heterocyclic TADF light-emitting material is selected from any one of the following structures: 。 5. Use of a boron-nitrogen heterocyclic TADF emitter according to claims 1-4, characterized in that, The boron-nitrogen heterocyclic TADF light-emitting material is applied to an organic electroluminescent device. 6.The application of boron-nitrogen heterocyclic TADF luminescent material according to claim 5, characterized in that, The boron-nitrogen heterocyclic TADF light-emitting material is applied to an organic layer of an organic electroluminescent device. 7.The application of the boron-nitrogen heterocyclic TADF light-emitting material according to claim 5, characterized in that, The boron-nitrogen heterocyclic TADF light-emitting material is applied to an emitting layer of an organic electroluminescent device. 8.The application of boron-nitrogen heterocyclic TADF luminescent material according to claim 5, wherein, The boron-nitrogen heterocyclic TADF light-emitting material is applied to an electron transport layer of an organic electroluminescent device. 9.The application of the boron-nitrogen heterocyclic TADF light-emitting material according to claim 5, characterized in that, The organic electroluminescent device comprises a substrate layer, an anode electrode layer, a hole injection layer, a hole transport layer, an electron blocking layer, an emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer and a cathode reflection electrode layer. 10.The application of boron-nitrogen heterocyclic TADF luminescent material according to claim 5, wherein, The boron-nitrogen heterocyclic TADF light-emitting material is applied to an emitting layer or an electron transport layer of an organic electroluminescent device, and the organic electroluminescent device has a blue light characteristic.

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