CN108178767B - A kind of organic small molecule light-emitting material based on pyrazine acceptor unit and its preparation method and application - Google Patents

Abstract

The invention discloses an organic small molecule light-emitting material based on a pyrazine acceptor unit. Pyrazine is used as the acceptor unit, and different kinds of aromatic amine groups are connected at different positions to obtain luminescence with different D-A-D structures. Molecules, realize the adjustment of the material conjugation length, the intramolecular charge transfer strength, the molecular weight of the material and the energy level distribution of the molecule. The invention also discloses a method for preparing the above-mentioned organic small molecule light-emitting material. The pyrazine acceptor unit and the aromatic amine compound are used as main reaction raw materials, and the target product is obtained through a series of reactions. The invention also discloses the application of the above organic small molecule light-emitting material. The molecular weight of the material of the present invention is determined, the structure is single, and the decomposition temperature is relatively high. Through the effective intramolecular charge transfer and the improvement of the triplet energy level of the molecule, the problem of carrier imbalance of the luminescent material can be overcome, and the stability of the device can be achieved. properties, can be used in organic light-emitting diode devices.

Description

A kind of organic small molecule light-emitting material based on pyrazine acceptor unit and preparation method thereof and application

technical field

The invention relates to the technical field of organic light-emitting materials, in particular to an organic small-molecule light-emitting material based on a pyrazine acceptor unit and a preparation method and application thereof.

Background technique

Information display is considered to be one of the three pillar technologies of the IT industry. The smooth development of it directly affects all aspects of people's lives and the level of economic development. The desired application of organic electroluminescence display technology lies in display and lighting. Due to its self-luminous characteristics, organic electroluminescence display technology uses an ultra-thin organic material coating, and the material emits light through the injection of low current. At the same time, the use of organic electroluminescence display technology has the characteristics of wide screen viewing angle, low energy consumption, simple manufacturing process, lower cost, extremely fast response time, and only one thousandth of the liquid crystal display. these unique advantages.

In organic light-emitting devices, compared with the light-emitting materials used in ordinary organic fluorescent light-emitting devices and organic phosphorescent light-emitting devices, thermally activated delayed fluorescence (TADF) materials do not contain expensive precious metal atoms, and can make full use of ordinary fluorescent materials. The utilized triplet excitons can achieve 100% exciton utilization of the device, making the design and characterization of this type of material a research hotspot of recent organic light-emitting diodes. Thermally activated delayed fluorescent materials can effectively promote the reverse intersystem crossing (RISC) process to effectively utilize triplet excitons, which endow these materials with unique optoelectronic properties, such as the special long excited state lifetime of TADF materials. It also shows considerable application potential in other optoelectronic fields. More importantly, the organic electroluminescent devices based on TADF materials show superior performance comparable to the organic phosphorescent light-emitting devices prepared with traditional rare metal complexes as the light-emitting layer.

By exploring the relationship between molecular structure design and device luminous efficiency, a method for preparing organic light-emitting materials with high efficiency and low roll-off is summarized, which can pave the way for the widespread commercial application of organic optoelectronic devices, which is of great academic significance and great economic value.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of the present invention is to provide an organic small molecule light-emitting material based on pyrazine acceptor unit, which has simple molecular structure, stable performance, high decomposition temperature, and can prepare morphological and Stable film.

Another object of the present invention is to provide a method for preparing the above-mentioned pyrazine acceptor unit-based organic small molecule light-emitting material, which is simple and easy to synthesize and purify.

Another object of the present invention is the above-mentioned pyrazine acceptor unit-based organic small molecule light-emitting material

The object of the present invention is achieved through the following technical solutions:

An organic small molecule light-emitting material based on a pyrazine acceptor unit, having any one of the following chemical structural formulas represented by P1n to P5n:

Wherein, Ar represents any one type of aromatic amine group in (1) to (4):

The organic small molecule light-emitting material based on the pyrazine acceptor unit has the structural formula shown in any one of the following P1 to P20:

The organic small molecule light-emitting material based on the pyrazine acceptor unit includes the following preparation steps:

(1) Preparation of any intermediate in a～d:

(2) under the protection of inert gas, add the intermediate prepared in step (1), the aromatic amine compound, the base and the catalyst to mix uniformly, heat and reflux for stirring reaction, through cooling, extraction, spin-drying solvent, column Chromatography to obtain the organic small molecule light-emitting material based on the pyrazine acceptor unit;

The molar ratio of the intermediate to the aromatic amine compound is 1:(2-2.5); the base is an organic base, and the molar ratio of the dosage to the aromatic amine compound is (1.8-2.5):1.

The step (1) of preparing any of the intermediates a to d is specifically: for the intermediates a to c, under the protection of an inert gas, adding dihalogen pyrazine and p-chlorobenzene substituted at different positions into the solvent Boric acid, alkali and tetrakis (triphenylphosphine) palladium are mixed uniformly, heated and refluxed for stirring reaction, and intermediates a to c are obtained through cooling, extraction, spin-drying solvent and column chromatography;

For the intermediate d, under the protection of inert gas, add 2,5-dibromopyrazine, p-bromothiophenol and alkali to the organic solvent, mix well, stir the reaction at room temperature, and then cool, extract and spin dry the solvent. , column chromatography to obtain intermediate d.

The temperature of the heating and refluxing reaction in step (2) is 90-110° C., and the reaction time is 12-24 h.

嗪或吩噻嗪中的任意一种。The aromatic amine compounds described in step (2) are 5-carboline, 9,9'-dimethylacridine, phene

either oxazine or phenothiazine.

The catalyst in step (2) is composed of palladium acetate and tri-tert-butylphosphine.

Include the following steps:

Under the protection of inert gas, 2,5-dibromopyrazine, aromatic amine compound, base and catalyst were added to the organic solvent and mixed evenly, heated and refluxed to stir the reaction, through cooling, extraction, spin-drying solvent, and column chromatography, obtaining the organic small molecule light-emitting material based on the pyrazine acceptor unit;

The molar ratio of the 2,5-dibromopyrazine to the aromatic amine compound is 1:(2～2.5); the base is an organic base, and the molar ratio of the dosage to the aromatic amine compound is (1.8～2.5) :1.

For the organic small molecule light-emitting material based on the pyrazine acceptor unit, the temperature of the heating and refluxing reaction in step (2) is 90-110° C., and the reaction time is 12-24 h.

The organic small molecule light-emitting material based on the pyrazine acceptor unit is used in organic light-emitting diodes.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The organic small molecule light-emitting material based on the pyrazine acceptor unit obtained in the present invention has simple structure, simple and convenient synthesis method, definite molecular weight, easy purification and good synthesis reproducibility.

(2) The organic small molecule light-emitting material based on the pyrazine acceptor unit obtained in the present invention has a higher decomposition temperature, and can prepare a thin film with stable morphology and performance.

(3) The organic small molecule light-emitting material based on the pyrazine acceptor unit obtained in the present invention, its structure can realize the regulation of the luminescent color and the current carrying by changing the type of the aromatic amine group, the power-donating property and the position of the connection The regulation of other optoelectronic physical properties such as electron transport.

Description of drawings

Figure 1 shows the absorption and emission spectra of P6 and P10 in toluene solution.

Figure 2 shows the absorption and emission spectra of P7 and P11 in toluene solution.

3 is a graph showing the relationship between current density-voltage-brightness of the organic light emitting diode device prepared in Example 21.

4 is a graph showing the relationship between current density-voltage-brightness of the organic light emitting diode device prepared in Example 22.

FIG. 5 is a graph showing the relationship between maximum external quantum efficiency and brightness of the organic light emitting diode device prepared in Example 21. FIG.

FIG. 6 is a graph showing the relationship between large external quantum efficiency and brightness of the organic light emitting diode device prepared in Example 22. FIG.

FIG. 7 is an electroluminescence spectrum diagram of the organic light emitting diode device prepared in Example 21. FIG.

FIG. 8 is an electroluminescence spectrum diagram of the organic light emitting diode device prepared in Example 22. FIG.

Detailed ways

The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto.

Example 1

An organic small molecule light-emitting material (P1) based on a pyrazine acceptor unit, the specific synthesis steps are shown in the following formula:

In a 250mL there-necked flask, add 713.67mg (3mmol) of 2,5-dibromopyrazine and 1.043g (6.2mmol) of carboline, dissolve with 100mL of toluene, then add 1.152g (12mmol) of palladium acetate 44.8g of sodium tert-butoxide mg (0.2 mmol), 0.6 mL of tri-tert-butylphosphine (1 mol/L toluene solution), heated to 110° C. under nitrogen atmosphere for reflux reaction for 20 h. After the reaction, the system was cooled to room temperature, toluene was removed by rotary evaporation, extracted several times with dichloromethane and water, the organic phase was taken out, the excess dichloromethane was removed by rotary evaporation, and 927 mg of product (P1) was obtained by column chromatography on silica gel, Yield 75%. Molecular formula: C ₂₆ H ₁₆ N ₆ ; M/Z=412.14; m/s=412.14 (100.0%), 413.15 (28.1%), 414.15 (2.7%), 413.14 (2.2%); Elemental analysis: C, 75.71; H, 3.91; N, 20.38.

Example 2

An organic small molecule light-emitting material (P2) based on a pyrazine acceptor unit, the specific synthesis steps are shown in the following formula:

The carboline in Example 1 was replaced with an equivalent of 1.298g (6.2mmol) of 9,9'-dimethylacridine, and the remaining raw materials and steps were the same as those in Example 1, and 979mg of product (P2) could be obtained. rate 66%. Molecular formula: C ₃₄ H ₃₀ N ₄ ; M/Z=494.25; m/s=494.25 (100.0%), 495.25 (36.8%), 496.25 (3.9%), 496.25 (2.7%); Elemental analysis: C, 82.56; H, 6.11; N, 11.33.

Example 3

An organic small molecule light-emitting material (P3) based on a pyrazine acceptor unit, the specific synthesis steps are shown in the following formula:

嗪1.136g(6.2mmol)，其余原料和步骤均与实施例1相同，可以得到796mg产物(P3)，产率60％。分子式：C₂₈H₁₈N₄O₂；M/Z＝442.14；m/s＝442.14(100.0％),443.15(30.3％),444.15(2.7％),444.15(1.7％)；元素分析：C,76.01；H,4.10；N,12.66；O,7.23。Replace the carboline in Example 1 with an equivalent amount of phene

1.136 g (6.2 mmol) of oxazine, other raw materials and steps are the same as in Example 1, 796 mg of product (P3) can be obtained, and the yield is 60%. Molecular formula: C ₂₈ H ₁₈ N ₄ O ₂ ; M/Z=442.14; m/s=442.14 (100.0%), 443.15 (30.3%), 444.15 (2.7%), 444.15 (1.7%); elemental analysis: C, 76.01; H, 4.10; N, 12.66; O, 7.23.

Example 4

An organic small molecule light-emitting material (P4) based on a pyrazine acceptor unit, the specific synthesis steps are shown in the following formula:

The carboline in Example 1 was replaced with an equivalent of 1.235 g (6.2 mmol) of phenothiazine, and the remaining raw materials and steps were the same as in Example 1, to obtain 897 mg of product (P4) with a yield of 63%. Molecular formula: C ₂₈ H ₁₈ N ₄ S ₂ ; M/Z=474.10; m/s=474.10 (100.0%), 475.10 (30.3%), 476.09 (9.0%), 477.10 (2.7%); elemental analysis: C, 70.86; H, 3.82; N, 11.81; S, 13.51.

Example 5

In this example, intermediate 1 is prepared first, and the specific synthesis steps are shown in the following formula:

Add 951.56 mg (4 mmol) of 2,5-dibromopyrazine and 1.313 g (8.4 mmol) of p-chlorophenylboronic acid to a 250 mL three-necked flask, dissolve with 90 mL of toluene and 30 mL of ethanol, and then add the prepared 2 mol/L 30 mL of potassium carbonate aqueous solution and 231.2 mg (0.2 mmol) of catalyst tetrakistriphenylphosphine palladium were heated to 80° C. for reflux reaction under nitrogen atmosphere for 24 h. After the reaction, the system was cooled to room temperature, toluene and ethanol were removed by rotary evaporation, extracted several times with dichloromethane and water, the organic phase was taken out, the excess dichloromethane was removed by rotary evaporation, and 1.10 g of the intermediate was obtained by column chromatography on silica gel 1. Yield 91%. Molecular formula: C ₁₆ H ₁₀ Cl ₂ N ₂ ; M/Z=300.02; m/s=300.02 (100%), 302.02 (63.9%), 301.03 (17.3%), 303.02 (11.1%); elemental analysis: C, 63.81; H, 3.35; Cl, 23.54; N, 9.30.

The specific synthesis steps of the organic small molecule light-emitting material (P5) based on the pyrazine acceptor unit are shown in the following formula:

In a 250mL there-necked flask, add 602.34mg (2mmol) of Intermediate 1 and 706.44mg (4.2mmol) of carboline, dissolve with 100mL of toluene, then add 768mg (8mmol) of sodium tert-butoxide 44.8mg (0.2mmol) of palladium acetate , 0.6 mL of tri-tert-butylphosphine (1 mol/L toluene solution), heated to 110 °C under nitrogen atmosphere for reflux reaction for 20 h. After the reaction was completed, the system was cooled to room temperature, toluene was removed by rotary evaporation, extracted with dichloromethane and water for several times, the organic phase was taken out, the excess dichloromethane was removed by rotary evaporation, and 824 mg of product (P5) was obtained by column chromatography on silica gel, Yield 73%. Molecular formula: C ₃₈ H ₂₄ N ₆ ; M/Z=564.21; m/s=564.21 (100.0%), 565.21 (41.1%), 566.21 (8.2%), 565.20 (2.2%); Elemental analysis: C, 80.83; H, 4.28; N, 14.88.

Example 6

An organic small molecule light-emitting material (P6) based on a pyrazine acceptor unit, the specific synthesis steps are shown in the following formula:

The carboline in Example 5 was replaced with an equivalent of 879.02mg (4.2mmol) of 9,9'-dimethylacridine, and the rest of the raw materials and steps were the same as in Example 5, and 880mg of product (P6) could be obtained. rate 68%. Molecular formula: C ₄₆ H ₃₈ N ₄ ; M/Z=646.31; m/s=646.31 (100.0%), 647.31 (49.8%), 648.32 (12.1%), 647.31 (1.5%); Elemental analysis: C, 85.42; H, 5.92; N, 8.66.

Example 7

An organic small molecule light-emitting material (P7) based on a pyrazine acceptor unit, the specific synthesis steps are shown in the following formula:

嗪769.48mg(4.2mmol)，其余原料和步骤均与实施例5相同，可以得到749mg产物(P7)，产率63％。分子式：C₄₀H₂₆N₄O₂；M/Z＝594.21；m/s＝594.21(100.0％),595.21(43.3％),596.21(9.1％),595.20(1.5％)；元素分析：C,80.79；H,4.41；N,9.42；O,5.38。Replace the carboline in Example 5 with an equivalent amount of phene

769.48 mg (4.2 mmol) of oxazine, other raw materials and steps are the same as in Example 5, 749 mg of product (P7) can be obtained with a yield of 63%. Molecular formula: C ₄₀ H ₂₆ N ₄ O ₂ ; M/Z=594.21; m/s=594.21 (100.0%), 595.21 (43.3%), 596.21 (9.1%), 595.20 (1.5%); elemental analysis: C, 80.79; H, 4.41; N, 9.42; O, 5.38.

Example 8

An organic small molecule light-emitting material (P8) based on a pyrazine acceptor unit, the specific synthesis steps are shown in the following formula:

The carboline in Example 5 was replaced with an equivalent of 836.93 mg (4.2 mmol) of phenothiazine, and the remaining raw materials and steps were the same as in Example 5, to obtain 815 mg of product (P8) with a yield of 65%. Molecular formula: C ₄₀ H ₂₆ N ₄ S ₂ ; M/Z=626.16; m/s=626.16 (100.0%), 627.16 (43.3%), 628.17 (9.1%), 628.16 (9.0%); elemental analysis: C, 76.65; H, 4.18; N, 8.94; S, 10.23.

Example 9

The present embodiment first prepares intermediate 2, and the specific synthesis steps are shown in the following formula:

The 2,5-dibromopyrazine in Example 1 was replaced with an equivalent 2,6-dichloropyrazine 595.88 mg (4 mmol), and the rest of the raw materials and steps were the same as in the preparation of Intermediate 1, and 1.02 g of intermediate was obtained. Body 2, 85% yield. Molecular formula: C ₁₆ H ₁₀ Cl ₂ N ₂ ; M/Z=300.02; m/s=300.02 (100%), 302.02 (63.9%), 301.03 (17.3%), 303.02 (11.1%); elemental analysis: C, 63.81; H, 3.35; Cl, 23.54; N, 9.30.

The organic small molecule light-emitting material (P9) based on the pyrazine acceptor unit, the specific synthesis steps are shown in the following formula:

The intermediate 1 in Example 5 was replaced with an equivalent amount of intermediate 2, and the remaining raw materials and steps were the same as those in Example 5, and 834 mg of product (P9) could be obtained with a yield of 74%. Molecular formula: C ₃₈ H ₂₄ N ₆ ; M/Z=564.21; m/s=564.21 (100.0%), 565.21 (41.1%), 566.21 (8.2%), 565.20 (2.2%); Elemental analysis: C, 80.83; H, 4.28; N, 14.88.

Example 10

An organic small molecule light-emitting material (P10) based on a pyrazine acceptor unit, the specific synthesis steps are shown in the following formula:

The carboline in Example 9 was replaced with an equivalent of 879.02 mg (4.2 mmol) of 9,9'-dimethylacridine, and the remaining raw materials and steps were the same as in Example 9, and 841 mg of product (P10) could be obtained. rate 65%. Molecular formula: C ₄₆ H ₃₈ N ₄ ; M/Z=646.31; m/s=646.31 (100.0%), 647.31 (49.8%), 648.32 (12.1%), 647.31 (1.5%); Elemental analysis: C, 85.42; H, 5.92; N, 8.66.

Example 11

An organic small molecule light-emitting material (P11) based on a pyrazine acceptor unit, the specific synthesis steps are shown in the following formula:

嗪769.48mg(4.2mmol)，其余原料和步骤均与实施例9相同，可以得到785mg产物(P11)，产率66％。分子式：C₄₀H₂₆N₄O₂；M/Z＝594.21；m/s＝594.21(100.0％),595.21(43.3％),596.21(9.1％),595.20(1.5％)；元素分析：C,80.79；H,4.41；N,9.42；O,5.38Replace the carboline in Example 9 with an equivalent amount of phene

769.48 mg (4.2 mmol) of oxazine, other raw materials and steps were the same as in Example 9, and 785 mg of product (P11) could be obtained with a yield of 66%. Molecular formula: C ₄₀ H ₂₆ N ₄ O ₂ ; M/Z=594.21; m/s=594.21 (100.0%), 595.21 (43.3%), 596.21 (9.1%), 595.20 (1.5%); elemental analysis: C, 80.79; H, 4.41; N, 9.42; O, 5.38

Example 12

An organic small molecule light-emitting material (P12) based on a pyrazine acceptor unit, the specific synthesis steps are shown in the following formula:

The carboline in Example 13 was replaced with an equivalent of 836.93 mg (4.2 mmol) of phenothiazine, and the remaining raw materials and steps were the same as those in Example 13, to obtain 853 mg of product (P12) with a yield of 68%. Molecular formula: C ₄₀ H ₂₆ N ₄ S ₂ ; M/Z=626.16; m/s=626.16 (100.0%), 627.16 (43.3%), 628.17 (9.1%), 628.16 (9.0%); elemental analysis: C, 76.65; H, 4.18; N, 8.94; S, 10.23.

Example 13

The present embodiment prepares intermediate 3, and the specific synthesis steps are shown in the following formula:

The 2,5-dibromopyrazine in the preparation of intermediate 1 was replaced with an equivalent of 595.88 mg (4 mmol) of 2,3-dichloropyrazine, and the remaining raw materials and steps were the same as in the preparation of intermediate 1, and 1.06 g could be obtained Intermediate 3, 88% yield. Molecular formula: C ₁₆ H ₁₀ Cl ₂ N ₂ ; M/Z=300.02; m/s=300.02 (100%), 302.02 (63.9%), 301.03 (17.3%), 303.02 (11.1%); elemental analysis: C, 63.81; H, 3.35; Cl, 23.54; N, 9.30.

The specific synthesis steps of the organic small molecule light-emitting material (P13) based on the pyrazine acceptor unit are shown in the following formula:

The intermediate 2 in Example 9 was replaced with an equivalent amount of intermediate 3, and the remaining raw materials and steps were the same as those in Example 9, and 869 mg of product (P13) could be obtained with a yield of 77%. Molecular formula: C ₃₈ H ₂₄ N ₆ ; M/Z=564.21; m/s=564.21 (100.0%), 565.21 (41.1%), 566.21 (8.2%), 565.20 (2.2%); Elemental analysis: C, 80.83; H, 4.28; N, 14.88.

Example 14

An organic small molecule light-emitting material (P14) based on a pyrazine acceptor unit, the specific synthesis steps are shown in the following formula:

The carboline in Example 13 was replaced with an equivalent of 879.02 mg (4.2 mmol) of 9,9'-dimethylacridine, and the remaining raw materials and steps were the same as in Example 13, and 802 mg of product (P10) could be obtained. rate 62%. Molecular formula: C ₄₆ H ₃₈ N ₄ ; M/Z=646.31; m/s=646.31 (100.0%), 647.31 (49.8%), 648.32 (12.1%), 647.31 (1.5%); Elemental analysis: C, 85.42; H, 5.92; N, 8.66.

Example 15

The specific synthesis steps of the organic small molecule light-emitting material (P15) based on the pyrazine acceptor unit are shown in the following formula:

嗪769.48mg(4.2mmol)，其余原料和步骤均与实施例13相同，可以得到770mg产物(P15)，产率65％。分子式：C₄₀H₂₆N₄O₂；M/Z＝594.21；m/s＝594.21(100.0％),595.21(43.3％),596.21(9.1％),595.20(1.5％)；元素分析：C,80.79；H,4.41；N,9.42；O,5.38。Replace the carboline in Example 13 with an equivalent of phene

769.48 mg (4.2 mmol) of oxazine, other raw materials and steps are the same as those in Example 13, 770 mg of product (P15) can be obtained with a yield of 65%. Molecular formula: C ₄₀ H ₂₆ N ₄ O ₂ ; M/Z=594.21; m/s=594.21 (100.0%), 595.21 (43.3%), 596.21 (9.1%), 595.20 (1.5%); elemental analysis: C, 80.79; H, 4.41; N, 9.42; O, 5.38.

Example 16

An organic small molecule light-emitting material (P16) based on a pyrazine acceptor unit, the specific synthesis steps are shown in the following formula:

The carboline in Example 13 was replaced with an equivalent of 836.93 mg (4.2 mmol) of phenothiazine, and the remaining raw materials and steps were the same as those in Example 13 to obtain 846 mg of product (P16) with a yield of 67%. Molecular formula: C ₄₀ H ₂₆ N ₄ S ₂ ; M/Z=626.16; m/s=626.16 (100.0%), 627.16 (43.3%), 628.17 (9.1%), 628.16 (9.0%); elemental analysis: C, 76.65; H, 4.18; N, 8.94; S, 10.23.

Example 17

The present embodiment first prepares intermediate 4, and the specific synthesis steps are shown in the following formula:

1.189g (5mmol) of 2,5-dibromopyrazine and 1.985g (10.5mmol) of p-bromothiophenol were added to a 250mL single-necked flask, dissolved in 80mL of acetonitrile, and then 2.76g (20mmol) of anhydrous potassium carbonate was added. , and stirred at room temperature for 18h. After the reaction, the acetonitrile in the reaction system was spin-dried, extracted with dichloromethane and water for several times, the organic phase was taken out, the excess methylene chloride was removed by rotary evaporation, and 1.64 g of intermediate 4 was obtained by silica gel column chromatography. The yield was 72%. Molecular formula: C ₁₆ H ₁₀ Br ₂ N ₂ S ₂ ; M/Z=453.86; m/s=453.86 (100.0%), 451.87 (51.4%), 455.86 (48.6%), 454.87 (17.3%); elemental analysis: C, 42.31; H, 2.22; Br, 35.18; N, 6.17; S, 14.12.

The specific synthesis steps of the organic small molecule light-emitting material (P17) based on the pyrazine acceptor unit are shown in the following formula:

The intermediate 3 in Example 13 was replaced with an equivalent amount of intermediate 4, and the remaining raw materials and steps were the same as those in Example 13, and 868 mg of product (P17) could be obtained with a yield of 69%. Molecular formula: C ₃₈ H ₂₄ N ₆ S ₂ ; M/Z=628.15; m/s=628.15 (100.0%), 629.15 (41.1%), 630.15 (9.0%), 630.16 (8.2%); elemental analysis: C, 72.59; H, 3.85; N, 13.37; S, 10.20.

Example 18

The specific synthesis steps of the organic small molecule light-emitting material (P18) based on the pyrazine acceptor unit are shown in the following formula:

The carboline in Example 17 was replaced with an equivalent of 879.02 mg (4.2 mmol) of 9,9'-dimethylacridine, and the remaining raw materials and steps were the same as those in Example 17, and 825 mg of product (P18) could be obtained. rate 58%. Molecular formula: C ₄₆ H ₃₈ N ₄ S ₂ ; M/Z=710.25; m/s=710.25 (100.0%), 711.26 (49.8%), 712.26 (12.1%), 712.25 (9.0%); Elemental analysis: C, 77.71; H, 5.39; N, 7.88; S, 9.02.

Example 19

An organic small molecule light-emitting material (P19) based on a pyrazine acceptor unit, the specific synthesis steps are shown in the following formula:

嗪769.48mg(4.2mmol)，其余原料和步骤均与实施例17相同，可以得到791mg产物(P19)，产率60％。分子式：C₄₀H₂₆N₄O₂S₂；M/Z＝658.15；m/s＝658.15(100.0％),659.15(43.3％),660.16(9.1％),660.15(9.0％)；元素分析：C,72.93；H,3.98；N,8.50；O,4.86；S,9.73。Replace the carboline in Example 17 with an equivalent of phene

769.48 mg (4.2 mmol) of oxazine, other raw materials and steps were the same as in Example 17, and 791 mg of product (P19) could be obtained with a yield of 60%. Molecular formula: C ₄₀ H ₂₆ N ₄ O ₂ S ₂ ; M/Z=658.15; m/s=658.15 (100.0%), 659.15 (43.3%), 660.16 (9.1%), 660.15 (9.0%); elemental analysis: C, 72.93; H, 3.98; N, 8.50; O, 4.86; S, 9.73.

Example 20

An organic small molecule light-emitting material (P20) based on a pyrazine acceptor unit, the specific synthesis steps are shown in the following formula:

The carboline in Example 21 was replaced with an equivalent of 836.93 mg (4.2 mmol) of phenothiazine, and the remaining raw materials and steps were the same as those in Example 21 to obtain 857 mg of product (P20) with a yield of 62%. Molecular formula: C ₄₀ H ₂₆ N ₄ S ₄ ; M/Z=690.10; m/s=690.10 (100.0%), 691.11 (43.3%), 692.10 (18.1%), 692.11 (9.1%); elemental analysis: C, 69.54; H, 3.79; N, 8.11; S, 18.56.

Example 21

The organic small molecule light-emitting materials (P6 and P10) based on the pyrazine acceptor unit of the present invention are used as the light-emitting layer of the organic light-emitting diode device, and the general device structure implemented is as follows: ITO/TAPC(30nm)/mCP(10nm)/DPEPO : Xwt% P6 or P10(35nm)/DPEPO(10nm)/TmPyPB(40nm)/LiF(1nm)/Al(100nm). Among them, ITO is the anode, TAPC is the hole injection layer, mCP is the hole transport layer, DPEPO is the luminescent material doped host and hole blocking layer, TmPyPB is the electron transport layer, LiF is the electron injection layer, Al is the cathode, X= 20 or 30.

The preparation process of the organic light-emitting diode device is as follows: the ITO transparent conductive glass is ultrasonically treated in a cleaning agent, then cleaned with deionized water, ultrasonically removed with a mixed solvent of acetone and ethanol, and baked in a clean environment until it is completely removed. Moisture, washed with UV light and ozone, and bombarded with low energy cations.

的沉积速率蒸镀有机材料层，其中在蒸镀发光层，将DPEPO和P6或P10分别放置在两个蒸镀源上，通过一定的沉积速率来控制两者的混合比例。之后再以

的沉积速率蒸镀LiF，以

的沉积速率蒸镀Al电极，得到本实施例的有机发光二极管器件。The above glass with anode ITO was placed in a vacuum chamber, evacuated to 1 × 10 ^-5 to 9 × 10 ^-3 Pa, and the above anode film was

The organic material layer is evaporated at a deposition rate of 100%, wherein in the evaporation of the light-emitting layer, DPEPO and P6 or P10 are placed on two evaporation sources respectively, and the mixing ratio of the two is controlled by a certain deposition rate. later with

Evaporating LiF at a deposition rate of

The Al electrode was evaporated at a deposition rate of 100000 , to obtain the organic light emitting diode device of this embodiment.

The current density-voltage-brightness curve diagram, the maximum external quantum efficiency-brightness relationship curve diagram, and the electroluminescence spectrum diagram of the organic light-emitting diode device of this embodiment are shown in Figure 3, Figure 5, and Figure 7, respectively. The basic characterization data are as follows: shown in Table 1. The absorption and emission spectra of P6 and P10 in toluene solution are shown in Figure 1. It can be seen from the photoluminescence and electroluminescence spectra that these two materials are sky blue materials with CT characteristics. From the relevant characterization data of the device, it can be found that the turn-on voltage of the device prepared by these two luminescent materials is relatively low. As long as 3.0V, the current density can reach a maximum of more than 40mA/cm ² . For P10, the maximum external quantum efficiency of the device can also reach the level of 12.8%, which obviously breaks through the limit of 5% of the maximum external quantum efficiency of traditional fluorescent materials.

Table 1. Basic data of organic light-emitting diode devices with P6 and P10 as light-emitting layers

Example 22

The organic small molecule light-emitting materials (P7 and P11) based on the pyrazine acceptor unit of the present invention are used as the light-emitting layer of the organic light-emitting diode device, and the general device structure implemented is as follows: ITO/TAPC (40nm)/CBP: X wt% P7 Or P11(25nm)/TmPyPB(55nm)/LiF(1nm)/Al(100nm), in which CBP is a luminescent material doped host, X=3 or 6, and the role of the remaining materials in the organic light-emitting diode device is the same as in Example 25 same.

The preparation process of the organic light emitting diode device is the same as that in Example 25 except that DPEPO is replaced with CBP in the process of evaporating the light emitting layer.

The current density-voltage-brightness curve diagram, the maximum external quantum efficiency-brightness relationship curve diagram and the electroluminescence spectrum diagram of the organic light-emitting diode device of this embodiment are shown in Figure 4, Figure 6, As shown in Figure 8, the basic characterization data is shown in Table 2. The absorption and emission spectra of P7 and P11 in toluene solution are shown in Figure 2. It can be seen from the photoinduced and electroluminescent spectra that these two materials are green materials with obvious CT characteristics. From the relevant characterization data of the device, it can be found that the turn-on voltage of the device prepared by these two luminescent materials is only 3.2V, the current density of the device of P7 can reach up to 150mA/cm ² or more, and the brightness is close to 10000cd/m ² . The maximum external quantum efficiency can also reach the level of 26%, and the maximum power efficiency can reach 89lm/W. Similarly, for the device of P10, the maximum external quantum efficiency is close to 16%, indicating that the devices prepared by these two materials have excellent luminescence performance.

Table 2. Basic data of organic light-emitting diode devices with P7 and P11 as light-emitting layers

Example 23

Using the organic small molecule light-emitting materials (P3 and P19) based on the pyrazine acceptor unit of the present invention as the light-emitting layer of the organic light-emitting diode device, the general device structure implemented is as follows: ITO/TAPC (20nm)/CBP: 3wt% P3 or P19(35nm)/TmPyPB(55nm)/LiF(1nm)/Al(100nm), in which CBP is a luminescent material doping host, and the other materials have the same functions in the organic light emitting diode device as in Example 25.

The preparation process of the organic light emitting diode device is the same as that in Example 25 except that DPEPO is replaced with CBP in the process of evaporating the light emitting layer.

Table 3. Basic data of organic light-emitting diode devices with P3 and P19 as light-emitting layers

The molecular formulas of TAPC, mCP, DPEPO, TmPyPB and CBP described in Examples 21 to 23 are respectively as follows:

嗪基团作为给体单元时，器件的启亮电压能保持在3～4V左右，即使对于共轭打断的硫桥结构分子，器件的最大外量子效率都能超过5％。同时相比于吖啶基团，对于使用给电性更强的吩

嗪基团作为给体单元时，材料的载流子传输性能和发光效率都有很大程度的提高，器件的最大外量子效率可以提高到26％左右。这些以基于吡嗪受体单元的有机小分子发光材料作发光层的有机发光二极管器件在发光效率方面相较于具有类似结构的发光分子有着较为明显的优势。It can be seen from the above device example results that for acridine and phene using large twist

When the oxazine group is used as the donor unit, the turn-on voltage of the device can be maintained at about 3-4V, and the maximum external quantum efficiency of the device can exceed 5% even for molecules with a conjugated broken sulfur bridge structure. At the same time, compared with the acridine group, for the use of phene with a stronger charge

When the oxazine group is used as the donor unit, the carrier transport performance and luminous efficiency of the material are greatly improved, and the maximum external quantum efficiency of the device can be increased to about 26%. These organic light-emitting diode devices using organic small molecule light-emitting materials based on pyrazine acceptor units as light-emitting layers have obvious advantages in light-emitting efficiency compared with light-emitting molecules with similar structures.

The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the described embodiments, and any other changes, modifications, substitutions, and combinations made without departing from the spirit and principle of the present invention , simplification, all should be equivalent replacement modes, and are all included in the protection scope of the present invention.

Claims (6)

1. An organic small molecule luminescent material based on a pyrazine acceptor unit is characterized by having the following structural formula of P19:

2. the preparation method of the pyrazine receptor unit-based organic small molecule light-emitting material of claim 1, comprising the following preparation steps:

(1) method for preparing intermediate d:

(2) under the protection of inert gas, adding the intermediate prepared in the step (1), phenoxazine, alkali and a catalyst into an organic solvent, uniformly mixing, heating, refluxing, stirring and reacting, and obtaining the organic micromolecule luminescent material based on the pyrazine acceptor unit through cooling, extraction, spin-drying the solvent and column chromatography;

the molar ratio of the intermediate d to the phenoxazine is 1 (2-2.5); the alkali is organic alkali, and the molar ratio of the dosage of the organic alkali to the phenoxazine is (1.8-2.5): 1.

3. The method for preparing an organic small molecule light-emitting material based on a pyrazine receptor unit according to claim 2, wherein the method for preparing the intermediate d in the step (1) is specifically as follows: under the protection of inert gas, adding 2, 5-dibromopyrazine, p-bromothiophenol and alkali into an organic solvent, uniformly mixing, stirring at room temperature for reaction, and cooling, extracting, spin-drying the solvent and carrying out column chromatography to obtain an intermediate d.

4. The method for preparing an organic small molecule luminescent material based on a pyrazine acceptor unit according to claim 2, wherein the temperature of the heating reflux reaction in the step (2) is 90-110 ℃, and the reaction time is 12-24 h.

5. The method for preparing an organic small molecule luminescent material based on pyrazine receptor unit according to claim 2, wherein the catalyst in step (2) consists of palladium acetate and tributyl phosphine.

6. Use of the pyrazine receptor unit-based organic small molecule light emitting material of claim 1 in organic light emitting diodes.

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