Cyanoquinoxaline red photothermal excitation delayed fluorescence material, synthesis method and application thereof

Abstract

The present invention provides a cyanoquinoxaline red light thermally excited delayed fluorescence material. The present invention designs the molecular structure, modifies the molecule with an aromatic amine group or an aromatic phosphine oxide group, improves its carrier transmission ability, inhibits the interaction between molecules, and adjusts the molecular configuration and electrical properties of the material without affecting the emission wavelength of the material, thereby preparing an efficient red light TADF material, thereby obtaining an electro-induced red light device with excellent comprehensive performance.

Description

[0001] This application is a divisional application of the Chinese invention patent application with application number 2021103580066. The invention name is Cyanoquinoxaline-type red photothermal excited delayed fluorescence materials, synthesis methods and applications thereof. The application date of the original application is April 1, 2021. Technical Field

[0002] The invention belongs to the technical field of electroluminescent materials, and in particular relates to a thermally excited delayed fluorescent material based on dicyanoquinoxaline compounds. Background Art

[0003] Organic Light Emitting Diodes (OLEDs) are highly favored due to their outstanding advantages such as ultra-light and ultra-thin, flexible and bendable, fast response speed, energy saving and environmental protection, and have become the leader in the new generation of flat panel display technology and lighting. The traditional first-generation organic electroluminescent materials are fluorescent materials. Because they only use singlet excitons to emit light, the internal quantum efficiency can only reach 25% in theory. Phosphorescent materials based on heavy metal complexes can simultaneously use singlet and triplet excitons to emit light and achieve 100% internal quantum efficiency, becoming the second-generation electroluminescent materials; however, the expensive cost and environmental pollution of metal complexes are still unavoidable problems.

[0004] In recent years, the emergence of Thermally Activated Delayed Fluorescence (TADF) materials has provided researchers with new design ideas. The characteristic of TADF materials is that triplet excitons can be converted into singlet excitons that can radiate through reverse intersystem crossing under the action of heat, thereby achieving simultaneous luminescence using singlet and triplet excitons and achieving 100% internal quantum efficiency. Therefore, TADF materials can not only fundamentally improve the luminescence efficiency, but also avoid the use of expensive heavy metals, and have become the third generation of organic electroluminescent materials. TADF materials are generally designed based on donor-acceptor structures, and the development of blue, green and yellow light materials is relatively rapid.

[0005] Most TADF luminescent molecules are pure organic donor (D)-acceptor (A) structures. The strong intramolecular charge transfer effect between DAs is used to reduce the singlet-triplet splitting energy and achieve efficient reverse intersystem crossing (RISC), thereby utilizing triplet excitons to emit light. Therefore, compared with fluorescence and phosphorescence technologies, TADF technology has outstanding advantages in 100% exciton utilization, low cost, environmental protection and sustainability. However, these DA-type molecules have high polarity and strong intermolecular interactions, which lead to serious triplet collision quenching effects, such as singlet-triplet (STA) and triplet-triplet annihilation (TTA). Obviously, due to the use of pure films of TADF molecules as the light-emitting layer, non-doped TADF devices place higher requirements on the light-emitting molecules themselves in terms of suppressing triplet quenching. Despite the severe challenges, the simplification of the device structure can further release the huge potential of TADF devices in large-scale preparation.

[0006] Recent studies have shown that triplet quenching can be effectively controlled in non-doped blue and green TADF devices. However, the luminescence efficiency of red TADF molecules is extremely sensitive to the doping concentration. The use of a non-doped luminescent layer structure even leads to an efficiency loss of up to 80%. In addition to the greater polarity of the molecules themselves, the energy gap of red and near-infrared TADF molecules is only 1.5-2eV, so they have more serious non-radiative transition processes. At present, few non-doped red TADF devices have an external quantum efficiency (EQE) that exceeds 10%. Therefore, the optoelectronic properties of the red TADF molecules themselves are the key bottleneck restricting the performance improvement of non-doped red TADF devices.

[0007] Based on the characteristics and requirements of red light TADF materials, we proposed four necessary conditions for constructing efficient red light TADF molecules: (1) reasonable molecular stacking and intermolecular interactions to balance charge transfer and quenching suppression; (2) the radiative process has an absolute advantage over the non-radiative process to obtain high luminescence efficiency; (3) the RISC efficiency is close to 100% to obtain the thermodynamic advantage of delayed fluorescence; and (4) fast charge recombination and exciton radiation to avoid quenching caused by exciton accumulation.

[0008] In order to realize red light TADF materials, it is usually necessary to further enhance the interaction between the donor and the acceptor. However, stronger interactions tend to increase the polarity of the material and enhance the intermolecular interaction, thus leading to severe concentration quenching. Therefore, how to obtain efficient red light TADF materials and develop a type of luminescent material that meets the above requirements is a difficult scientific problem to overcome. Summary of the invention

[0009] In order to solve the above problems, the inventors use molecular design to provide a cyanoquinoxaline-based red light-heat-excited delayed fluorescent material. The material is a cyanoquinoxaline compound modified with an aromatic amine group and an aromatic phosphine oxide group. By introducing an aromatic amine group and an aromatic phosphine oxide group, the carrier transmission capacity can be improved, and the steric hindrance effect of the aromatic phosphine oxide group is used to weaken the intermolecular interaction, thereby weakening the quenching effect. At the same time, the phosphine oxide group is used to block the conjugated extension to ensure the emission wavelength of the material, thereby obtaining a class of stable red light-heat-excited delayed fluorescent materials, and completing the present invention.

[0010] The object of the present invention is to provide the following aspects:

[0011] 1. Provide a cyanoquinoxaline red light thermal excitation delayed fluorescent material, the material is a dicyanoquinoxaline compound, the compound uses 6,7-dicyano-quinoxaline or 5,8-dicyano-quinoxaline as an acceptor, and has the following general structural formula:

[0012]

[0013] in,

[0014] R1, R2, R3, and R4 are each independently selected from hydrogen, C1-C5 alkyl, C1-C5 alkoxy, or phenyl.

[0015] X1, Y1, X2, and Y2 are each independently selected from hydrogen, an alkyl group, an aromatic amine group, or an aromatic phosphine oxygen group.

[0016] In a preferred embodiment of the present invention, the compound is a 2-aromatic amino-dicyanoquinoxaline compound, a 2,3-diaromatic amino-dicyanoquinoxaline compound or a 2-aromatic amino-3-aromatic phosphino-dicyanoquinoxaline compound.

[0017] Preferably, the cyanoquinoxaline red light thermally excited delayed fluorescent material is one of Compounds 1 to 12:

[0018]

[0019] More preferably, the cyanoquinoxaline red photothermal excitation delayed fluorescent material is one of Compounds 9 to 12.

[0020] The cyanoquinoxaline red light-heat-excited delayed fluorescent material is prepared from raw materials including halogenated aromatic ketone compounds and diaminophthalonitrile compounds. Preferably, the material is prepared by a method comprising the following steps:

[0021] Step 1: Add a halogenated aromatic ketone compound and reactant I into a solvent, stir and react to obtain intermediate I.

[0022] Step 2: Add intermediate I and reactant II into a solvent and reflux to obtain intermediate II or a dicyanoquinoxaline compound.

[0023] When the reactant II is an aromatic phosphine oxide compound, the method further comprises: step 3, adding the intermediate II and the aromatic amine compound into a solvent, and performing a reflux reaction to obtain a dicyanoquinoxaline compound.

[0024] 2. Provide a method for preparing the cyanoquinoxaline red light-heat-excited delayed fluorescent material, wherein the material is prepared from raw materials including a halogenated aromatic ketone compound and a diaminophthalonitrile compound. Preferably, the method comprises the following steps:

[0025] Step 1: Add a halogenated aromatic ketone compound and reactant I into a solvent, stir and react to obtain intermediate I.

[0026] Step 2: Add intermediate I and reactant II into a solvent and reflux to obtain intermediate II or a dicyanoquinoxaline compound.

[0027] When reactant II is an aromatic phosphine oxide compound, the method further comprises:

[0028] Step 3: Add the intermediate II and the aromatic amine compound III into a solvent and reflux to obtain a dicyanoquinoxaline compound.

[0029] 3. Provide a use of a cyanoquinoxaline-based red light thermally excited delayed fluorescence material for preparing an electroluminescent red light device.

[0030] 4. Provide an electro-red light device, wherein the guest material of the light-emitting layer of the electro-red light device comprises a cyanoquinoxaline-based red light thermally excited delayed fluorescent material.

[0031] The electro-red light device comprises a substrate layer, a conductive anode layer, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode conductive layer.

[0032] 5. Provide a method for preparing the electro-red light device, the method comprising the following steps:

[0033] 1. preparing an anode conductive layer;

[0034] 2. preparing a hole injection layer;

[0035] 3. Preparation of hole transport layer;

[0036] 4. preparing a light-emitting layer;

[0037] 5. preparing an electron transport layer;

[0038] 6. preparing an electron injection layer;

[0039] 7. Prepare a cathode conductive layer, encapsulate it, and obtain a thermally excited delayed fluorescence electroluminescent device.

[0040] The present invention has the following beneficial effects:

[0041] (1) The aromatic amine group introduced into the cyanoquinoxaline red photothermal excited delayed fluorescent material provided by the present invention is a strong electron donating group, which can improve the carrier transmission capacity. The steric effect of the aromatic phosphine oxide group can be used to obtain a reasonable molecular stacking state and intermolecular force. At the same time, the phosphine oxide group is used to block the conjugated extension, thereby weakening the quenching effect and ensuring the emission wavelength of the material.

[0042] (2) The phosphine oxide (P=O) group connects the aromatic groups through the CP saturated bond, which can effectively block the extension of the conjugation and ensure that the emission wavelength of the material is not affected; at the same time, the P=O group has the effect of polarizing the molecule, which can improve the electron injection and transmission ability of the material; in addition, the triphenylphosphine oxide group also has a large steric hindrance effect, which can effectively inhibit the interaction between molecules.

[0043] (3) The present invention designs the molecular structure to have reasonable molecular stacking and intermolecular interaction to take into account both charge transmission and quenching suppression, thereby obtaining a red light TADF material.

[0044] (4) The maximum external quantum efficiency of the electro-red light device prepared in the present invention can reach 31.4%, and the emission wavelength can reach 612 nm, which has good electro-red light device performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The ultraviolet fluorescence spectrum of compound 5 in Example 5 of the present invention is shown, wherein ■ represents the ultraviolet spectrum of compound 5 in toluene solvent at room temperature, ● represents the ultraviolet spectrum of compound 5 solid film, □ represents the fluorescence spectrum of compound 5 in toluene solvent, ○ represents the fluorescence spectrum of compound 5 solid film, Δ and ▽ represent the fluorescence spectra of compound 5 in toluene solvent and solid film under 77K conditions, respectively;

[0046] Figure 2 The thermogravimetric analysis spectrum of compound 5 in Example 5 of the present invention is shown;

[0047] Figure 3The ultraviolet fluorescence spectrum of compound 6 in Example 6 of the present invention is shown, wherein ■ represents the ultraviolet spectrum of compound 6 in toluene solvent, ● represents the ultraviolet spectrum of compound 6 solid film, □ represents the fluorescence spectrum of compound 6 in toluene solvent, ○ represents the fluorescence spectrum of compound 6 solid film, Δ and ▽ represent the fluorescence spectra of compound 6 in toluene solvent and solid film under 77K condition, respectively;

[0048] Figure 4 The thermogravimetric analysis spectrum of compound 6 in Example 6 of the present invention is shown;

[0049] Figure 5 The electroluminescence spectrum of the doped electroluminescent red TADF device prepared by the compound 1 in Example 1 of the present invention is shown;

[0050] Figure 6 The electroluminescence spectrum of the doped electroluminescent red light TADF device prepared by compound 2 in Example 2 of the present invention is shown;

[0051] Figure 7 The electroluminescence spectrum of the doped electroluminescent red TADF device prepared by compound 3 in Example 3 of the present invention is shown;

[0052] Figure 8 The electroluminescence spectrum of the doped electroluminescent red TADF device prepared by compound 4 in Example 4 of the present invention is shown;

[0053] Fig. 9 The electroluminescence spectrum of the doped electroluminescent red TADF device prepared by compound 5 in Example 5 of the present invention is shown;

[0054] Fig.10 The electroluminescence spectrum of the doped electroluminescent red TADF device prepared by compound 6 in Example 6 of the present invention is shown;

[0055] Fig.11 The electroluminescence spectrum of the doped electroluminescent red TADF device prepared by compound 7 in Example 7 of the present invention is shown;

[0056] Fig.12 The electroluminescence spectrum of the doped electroluminescent red TADF device prepared by compound 8 in Example 8 of the present invention is shown;

[0057] Fig.13 The electroluminescence spectrum of the doped electroluminescent red TADF device prepared by compound 9 in Example 9 of the present invention is shown;

[0058] Fig.14 The electroluminescence spectrum of the doped electroluminescent red TADF device prepared by compound 10 in Example 10 of the present invention is shown;

[0059] Fig.15 The electroluminescence spectrum of the doped electroluminescent red TADF device prepared by compound 11 in Example 11 of the present invention is shown;

[0060] Fig.16 The electroluminescence spectrum of the doped electroluminescent red TADF device prepared by compound 12 in Example 12 of the present invention is shown;

[0061] Fig.17 The voltage-current density relationship curve of the doped electro-red light TADF device prepared by the compound 11 in Example 11 of the present invention is shown;

[0062] Fig.18 The voltage-brightness relationship curve of the doped electro-red light TADF device prepared by compound 11 in Example 11 of the present invention is shown;

[0063] Fig.19 The brightness-current efficiency relationship curve of the doped electro-red light TADF device prepared by compound 11 in Example 11 of the present invention is shown;

[0064] Fig. 20 The brightness-power efficiency relationship curve of the doped electro-red TADF device prepared by compound 11 in Example 11 of the present invention is shown;

[0065] Fig.21 The brightness-external quantum efficiency relationship curve of the doped electro-red light TADF device prepared by compound 11 in Example 11 of the present invention is shown. DETAILED DESCRIPTION

[0066] The present invention is described in detail below through specific implementation modes, and the characteristics and advantages of the present invention will become clearer and more specific with these descriptions.

[0067] The present invention provides a cyanoquinoxaline red light thermal excitation delayed fluorescent material, which is a dicyanoquinoxaline compound, and the compound uses 6,7-dicyano-quinoxaline or 5,8-dicyano-quinoxaline as an acceptor, and has the following general structural formula:

[0068]

[0069] in,

[0070] R1, R2, R3, and R4 are each independently selected from hydrogen, C1-C5 alkyl, C1-C5 alkoxy or phenyl, preferably selected from hydrogen or C1-C5 alkyl, more preferably hydrogen.

[0071] X1, Y1, X2, Y2 are each independently selected from hydrogen, alkyl, aromatic amine group or aromatic phosphine group, preferably selected from hydrogen, aniline group, diphenylamine group, triphenylamine group, substituted triphenylaminophenyl group, triphenylaminophenyl, diphenylphosphine group or triphenylphosphine group, more preferably hydrogen, triphenylamine, triphenylaminophenyl or triphenylphosphine group.

[0072] In a preferred embodiment of the present invention, the compound is a 2-aromatic amino-dicyanoquinoxaline compound, a 2,3-diaromatic amino-dicyanoquinoxaline compound or a 2-aromatic amino-3-aromatic phosphino-dicyanoquinoxaline compound.

[0073] The 2-aromatic amino-dicyanoquinoxaline compound is that X1 and X2 are independently selected from aromatic amine groups, preferably selected from aniline groups, diphenylamine groups, triphenylamine groups, triphenylamine phenyl groups containing substituents, triphenylamine phenyl, more preferably triphenylamine or triphenylamine phenyl; Y1 and Y2 are hydrogen or alkyl, preferably hydrogen.

[0074] The 2,3-diaromaticamino-dicyanoquinoxaline compound is that X1 and Y1 are the same substituents, X2 and Y2 are the same substituents, and X1 and X2 are independently selected from aromatic amine groups, preferably selected from aniline groups, diphenylamine groups, triphenylamine groups, triphenylamine-containing substituted triphenylamine-phenyl groups, triphenylamine-phenyl, and more preferably triphenylamine or triphenylamine-phenyl.

[0075] The 2-aromatic amino-3-aromatic phosphinoyl-dicyanoquinoxaline compound is that X1 and X2 are each independently selected from aromatic amine groups, preferably selected from aniline groups, diphenylamine groups, triphenylamine groups, triphenylamine phenyl groups containing substituents, triphenylamine phenyl, more preferably triphenylamine or triphenylamine phenyl; Y1 and Y2 are each independently selected from aromatic phosphinoyl groups, preferably selected from diphenylphosphinoyl groups or triphenylphosphinoyl groups, more preferably triphenylphosphinoyl groups.

[0076] Preferably, the cyanoquinoxaline red light thermally excited delayed fluorescent material is one of Compounds 1 to 12:

[0077]

[0078]

[0079]

[0080] More preferably, the cyanoquinoxaline red photothermal excitation delayed fluorescent material is one of Compounds 9 to 12.

[0081] The aromatic amine group introduced into the cyanoquinoxaline red photothermal excited delayed fluorescence material provided by the present invention is a strong electron donating group, which can improve the carrier transmission capacity. The steric hindrance effect of the aromatic phosphine oxide group can be used to obtain a reasonable molecular stacking state and intermolecular forces. At the same time, the phosphine oxide group is used to block the conjugated extension, thereby weakening the quenching effect and ensuring the emission wavelength of the material.

[0082] In recent years, aromatic phosphine oxide materials have aroused great interest due to their outstanding advantages and have been used to design and construct efficient electroluminescent host materials and luminescent materials. The phosphine oxide (P=O) group connects the aromatic groups through the CP saturated bond, which can effectively block the extension of conjugation and ensure that the emission wavelength of the material is not affected; at the same time, the P=O group has the function of polarizing molecules, which can improve the electron injection and transmission ability of the material; in addition, the triphenylphosphine oxide group also has a large steric hindrance effect, which can effectively inhibit the interaction between molecules. Therefore, the introduction of the phosphine oxide group into the donor-acceptor structure can adjust the molecular configuration and electrical properties of the material without affecting the emission wavelength of the material, so as to realize efficient red light TADF materials.

[0083] The present invention also provides a method for preparing the cyanoquinoxaline red light-heat-excited delayed fluorescent material, wherein the material is prepared from raw materials including a halogenated aromatic ketone compound and a diaminophthalonitrile compound. Preferably, the method comprises the following steps:

[0084] Step 1: Add a halogenated aromatic ketone compound and reactant I into a solvent, stir and react to obtain intermediate I.

[0085] The halogenated aromatic ketone compound is selected from halogenated phenyl monoketone or halogenated phenyl diketone, preferably 1-halogenated phenyl-2-halogenated alkane-1-one or halogenated phenyl-1,2-dione, more preferably 1-halogenated phenyl-2-halogenated ethane-1-one or halogenated phenylethanedione, such as 2-bromo-1-(4-bromophenyl)ethane-1-one, 1,2-bis(4-bromophenyl)ethane-1,2-dione.

[0086] The reactant I is a diaminophthalonitrile compound or an aromatic amine compound I. When the reactant I is a diaminophthalonitrile compound, the intermediate I is a cyanoquinoxaline intermediate I-1; when the reactant I is an aromatic amine compound I, the intermediate I is an aromatic aminobenzophenone intermediate. When the reactant I is a diaminophthalonitrile compound:

[0087] The diaminophthalonitrile compound is selected from an ortho-diaminophthalonitrile compound or an ortho-diaminoterephthalonitrile compound, and has a molecular structure of formula (3) or formula (4):

[0088]

[0089] Among them, R1, R2, R3, and R4 are each independently selected from hydrogen, C1-C5 alkyl, C1-C5 alkoxy or phenyl, preferably selected from hydrogen or C1-C5 alkyl, and more preferably hydrogen.

[0090] The diaminophthalonitrile compound is preferably 4,5-diaminophthalonitrile or 2,3-diaminoterephthalonitrile.

[0091] In one embodiment of the present invention, the reaction is carried out in the presence of a catalyst, the catalyst is selected from a phase transfer catalyst, preferably a quaternary ammonium salt, such as triethylenediamine, hexadecyltrimethylammonium bromide, more preferably hexadecyltrimethylammonium bromide. The molar ratio of the halogenated aromatic ketone compound to the catalyst is (5-10):(0.8-4), preferably (5-10):(1.2-3).

[0092] The solvent is selected from one or more of alcohol solvents, organic acid solvents and water, preferably one or more of methanol, ethanol, acetic acid and water, more preferably water or acetic acid.

[0093] The reaction time is 8-16h, preferably 10-14h; the reaction temperature is the reflux temperature of the solvent, such as 50-140°C, preferably 70-130°C, preferably 90-120°C, for example 100°C, 118°C.

[0094] The molar ratio of the halogenated aromatic ketone compound to the diaminophthalonitrile compound is 1:(0.6-1.6), preferably 1:(0.8-1.4), and more preferably 1:(1-1.2).

[0095] The molar volume ratio of the halogenated aromatic ketone compound to the solvent is 1 mmol:(3-20) mL, preferably 1 mmol:(4-15) mL, more preferably 1 mmol:(5-10) mL, such as 1 mmol:5 mL, 1 mmol:10 mL.

[0096] After the reaction is completed, the cyanoquinoxaline intermediate I-1 is obtained through post-treatment, which includes separation and washing.

[0097] The separation is performed by filtration, preferably by suction filtration, and the washing is performed by washing with an alcohol solvent, preferably by anhydrous ethanol.

[0098] When reactant Ⅰ is aromatic amine compound Ⅰ:

[0099] The aromatic amine compound I is selected from primary amines or secondary amines, preferably aniline or diphenylamine, more preferably diphenylamine.

[0100] The solvent is one or more of ether solvents or aromatic hydrocarbon solvents, preferably one or more of ether, toluene and xylene, more preferably xylene.

[0101] The reaction is carried out in the presence of a catalyst, and the catalyst is selected from a palladium catalyst, preferably a palladium-phosphorus complex or tris-dibenzylideneacetone dipalladium, and more preferably tris-dibenzylideneacetone dipalladium. Preferably, the tris-dibenzylideneacetone dipalladium is used in combination with an alkyl phosphine, and preferably tris-dibenzylideneacetone dipalladium is used in combination with tri-tert-butylphosphine.

[0102] The reaction is carried out in the presence of a base, and the base is selected from tert-butoxide or an alkali metal weak acid salt, preferably an alkali metal carbonate, and more preferably cesium carbonate.

[0103] The reaction temperature is the reflux temperature of the solvent, such as 110-160°C, preferably 125-145°C, such as 135°C; the reaction time is 8-16h, preferably 10-14h.

[0104] The molar ratio of the halogenated aromatic ketone compound to the aromatic amine compound I is 1:(2.0-2.7), preferably 1:(2.1-2.5), and more preferably 1:(2.2-2.3).

[0105] The molar ratio of the halogenated aromatic ketone compound to the catalyst is 2:(0.04-0.16), preferably 2:(0.06-0.14), and more preferably 2:(0.08-0.12).

[0106] The molar ratio of the halogenated aromatic ketone compound to the base is 2:(6-18), preferably 2:(8-16), and more preferably 2:(10-14).

[0107] Preferably, the molar ratio of trisdibenzylideneacetone dipalladium to tri-tert-butylphosphine is 1:(3-9), preferably 1:(4-8), and more preferably 1:(5-7).

[0108] After the reaction is completed, ice water is added to the reaction solution, and then the reaction solution is post-treated to obtain aromatic amino aromatic ketone intermediate I-2. The post-treatment includes extraction, drying, solvent removal and purification.

[0109] The extraction is performed using water and halogenated alkane, the organic layer is dried, and the organic solvent is removed to obtain a crude product. The crude product is purified by column chromatography using petroleum ether and dichloromethane.

[0110] Step 2: Add intermediate I and reactant II into a solvent and reflux to obtain intermediate II or a dicyanoquinoxaline compound.

[0111] The reactant II is selected from diaminophthalonitrile compounds, aromatic amine compounds II or aromatic phosphine oxide compounds.

[0112] When the intermediate I is a cyanoquinoxaline intermediate I-1, the reactant II is an aromatic amine compound II or an aromatic phosphine oxide compound.

[0113] The cyanoquinoxaline intermediate Ⅰ-1 reacts with the aromatic amine compound Ⅱ to obtain dicyanoquinoxaline compounds, such as compound 1 to compound 4, that is, cyanoquinoxaline red photothermal excitation delayed fluorescent materials.

[0114] The aromatic amine compound II is selected from aniline, diphenylamine or triphenylamine-4-boric acid pinacol ester, preferably diphenylamine or triphenylamine-4-boric acid pinacol ester. The molar ratio of the cyanoquinoxaline intermediate I-1 to the aromatic amine compound II is 2:(2.0-3.1), preferably 2:(2.1-2.8), and more preferably 2:(2.2-2.5).

[0115] The reaction is carried out in the presence of a catalyst, and the catalyst is selected from a palladium catalyst, preferably an organic palladium, and more preferably tetrakistriphenylphosphine palladium or trisdibenzylideneacetone dipalladium. The molar ratio of the cyanoquinoxaline intermediate Ⅰ-1 to the catalyst is 2:(0.03-0.09), preferably 2:(0.04-0.08), and more preferably 2:(0.05-0.07). Preferably, when a non-palladium phosphine complex is used as a catalyst, an organic phosphine is added to assist the catalysis, such as adding tri-tert-butyl phosphine and trisdibenzylideneacetone dipalladium. The molar ratio of the organic phosphine to the palladium catalyst is (20-40):6, preferably (28-32):6.

[0116] The reaction is carried out in the presence of an alkaline substance, wherein the base is selected from an alkali metal carbonate or an organic base, preferably an alkali metal carbonate, more preferably potassium carbonate or sodium carbonate. The molar ratio of the cyanoquinoxaline intermediate I-1 to the base is 2:(3-9), preferably 2:(4-8), more preferably 2:(5-7).

[0117] The solvent is selected from one or more of an alcohol solvent, an ether solvent, an aromatic hydrocarbon solvent and water, preferably one or more of methanol, ethanol, tetrahydrofuran, toluene, xylene and water, more preferably one or more of xylene, tetrahydrofuran and water. The molar volume ratio of the cyanoquinoxaline intermediate I-1 to the solvent is 2mmol:(4-16)mL, preferably 2mmol:(6-14)mL, more preferably 2mmol:(8-12)mL. When the solvent is tetrahydrofuran and water, the volume ratio of the two is (2-4):1, preferably (2.5-3.5):1, more preferably 3:1.

[0118] The reaction temperature is the reflux temperature of the solvent, such as 60-160°C, preferably 80-140°C, for example 80°C, 135°C, and the reaction time is 8-16h, preferably 10-14h.

[0119] After the reaction is completed, ice water is poured into the reaction solution, and the reaction solution is post-treated to obtain a cyanoquinoxaline red photothermal excitation delayed fluorescent material. The post-treatment includes extraction, drying and purification.

[0120] The extraction is performed using water and halogenated alkane, preferably water and dichloromethane, and the organic layer is dried to remove the organic solvent to obtain a crude product. The crude product is purified by column chromatography using petroleum ether and dichloromethane.

[0121] The cyanoquinoxaline intermediate Ⅰ-1 reacts with an aromatic phosphine oxide compound to obtain intermediate Ⅱ.

[0122] The aromatic phosphine oxide compound is selected from phenylphosphine compounds, preferably diphenylphosphine chloride or phenylphosphine dichloride, more preferably diphenylphosphine chloride. The molar ratio of cyanoquinoxaline intermediate I-1 to the aromatic phosphine oxide compound is 2:(0.5-6), preferably 2:(1-5), more preferably 2:(2-4).

[0123] The reaction is carried out in the presence of a catalyst, the catalyst is selected from a palladium catalyst, preferably selected from an organic palladium, and more preferably palladium acetate. The molar ratio of the cyanoquinoxaline intermediate I-1 to the catalyst is 2:(0.001-0.06), preferably (2-3):(0.005-0.04), and more preferably (2-3):(0.01-0.02).

[0124] The reaction is carried out in the presence of an alkaline substance, wherein the base is selected from an alkali metal weak acid salt or an organic base, preferably selected from an alkali metal weak acid salt, and more preferably potassium acetate. The molar ratio of the cyanoquinoxaline intermediate I-1 to the base is (2-3):(2-18), preferably (2-3):(4-15), and more preferably (2-3):(6-12).

[0125] The solvent is selected from one or more of an alcohol solvent, an ether solvent and an amide solvent, preferably one or more of methanol, ethanol, tetrahydrofuran and N,N-dimethylformamide, more preferably N,N-dimethylformamide. The molar volume ratio of the cyanoquinoxaline intermediate I-1 to the solvent is 2mmol:(6-14)mL, preferably 2mmol:(7-13)mL, more preferably 2mmol:(8-12)mL.

[0126] The reaction temperature is 100-160°C, preferably 110-150°C, more preferably 120-140°C, and the reaction time is 8-16h, preferably 10-14h.

[0127] After the reaction is completed, ice water is poured in, extraction is performed, and an oxidant is added to the organic layer to react for 4-6 hours.

[0128] The oxidant is selected from hydrogen peroxide or peracetic acid, preferably hydrogen peroxide, more preferably a 25% to 35% aqueous hydrogen peroxide solution. The molar ratio of the aromatic phosphine oxide compound to the oxidant is 1:(0.9-1.6), preferably 1:(1.0-1.4), more preferably 1:(1.1-1.2). The oxidation reaction temperature is -5 to 5°C, more preferably -5 to 0°C.

[0129] After the oxidation reaction is completed, the reaction solution is post-treated to obtain intermediate II. The post-treatment includes extraction, drying and purification.

[0130] The extraction is performed using water and halogenated alkane, preferably water and dichloromethane, and the organic layer is dried to remove the organic solvent to obtain a crude product. The crude product is purified by column chromatography using petroleum ether and ethyl acetate.

[0131] When the intermediate I is an aromatic aminobenzophenone intermediate I-2, the reactant II is a diaminobenzonitrile compound, and the reaction produces a dicyanoquinoxaline compound, such as compound 5 and compound 6, i.e., a cyanoquinoxaline red photothermal excited delayed fluorescent material.

[0132] The diaminophthalonitrile compound has the same selection range as that in step 1.

[0133] The molar ratio of the aromatic aminobenzophenone intermediate Ⅰ-2 to the diaminobenzonitrile compound is 1:(0.6-1.6), preferably 1:(0.8-1.4), and more preferably 1:(1-1.2).

[0134] The solvent is selected from one or more of an alcohol solvent, an organic acid solvent and water, preferably one or more of methanol, ethanol, acetic acid and water, more preferably acetic acid. The molar volume ratio of the aromatic amino phenone intermediate I-2 to the solvent is 1:(4-16), preferably 1:(6-14), more preferably 1:(8-12).

[0135] The reaction time is 8-16 hours, preferably 10-14 hours; the reaction temperature is 80-140°C, preferably 90-130°C, more preferably 100-120°C.

[0136] After the reaction is completed, the dicyanoquinoxaline compounds are obtained through post-treatment, which includes neutralization, extraction and purification.

[0137] In one embodiment of the present invention, the aromatic aminobenzophenone intermediate Ⅰ-2 is first reacted with aromatic amino-boric acid pinacol ester to obtain intermediate III, which is then reacted with diaminobenzonitrile compounds to obtain dicyanoquinoxaline compounds, such as compound 7 and compound 8.

[0138] The molar ratio of the aromatic amino phenone intermediate Ⅰ-2 to the aromatic amino-boric acid pinacol ester is 2:(2.0-3.1), preferably 2:(2.1-2.8), and more preferably 2:(2.2-2.5).

[0139] The reaction is carried out in the presence of a catalyst, the catalyst is selected from a palladium catalyst, preferably a palladium phosphine complex, and more preferably tetrakistriphenylphosphine palladium. The molar ratio of the aromatic aminobenzophenone intermediate I-2 to the catalyst is 2:(0.04-0.16), preferably 2:(0.06-0.14), and more preferably 2:(0.08-0.12).

[0140] The reaction is carried out in the presence of an alkaline substance, the base is selected from alkali metal carbonates or organic bases, preferably alkali metal carbonates, more preferably potassium carbonate or sodium carbonate. The molar ratio of the aromatic aminobenzophenone intermediate I-2 to the base is 1:(3-9), preferably 1:(4-8), more preferably 1:(5-7).

[0141] The solvent is selected from one or more of an alcohol solvent, an ether solvent and water, preferably one or more of methanol, ethanol, tetrahydrofuran and water, and more preferably a mixed solvent of tetrahydrofuran and water. The molar volume ratio of the aromatic aminobenzophenone intermediate Ⅰ-2 to the solvent is 2mmol:(6-14)mL, preferably 2mmol:(7-13)mL, and more preferably 2mmol:(8-12)mL. Preferably, the volume ratio of tetrahydrofuran to water is (2-4):1, preferably (2.5-3.5):1, and more preferably 3:1.

[0142] The reaction temperature is the reflux temperature of the solvent, such as 70-100° C., preferably 80-90° C., and the reaction time is 8-16 h, preferably 10-14 h.

[0143] After the reaction is completed, ice water is poured in, and the reaction solution is post-treated to obtain intermediate III. The post-treatment includes extraction, drying and purification. The product is extracted with water and dichloromethane, the organic layers are combined, and the organic solvent is removed after drying to obtain a crude product, which is purified by column chromatography using a mixed solvent of petroleum ether and dichloromethane as an eluent.

[0144] The intermediate III is then subjected to a reflux reaction with a diaminophthalonitrile compound in a solvent. After the reaction is completed, ice water is poured into the reaction solution, and the reaction solution is post-treated to obtain a dicyanoquinoxaline compound, namely, a cyanoquinoxaline red photothermal excitation delayed fluorescent material.

[0145] The diaminophthalonitrile compound has the same selection range as that in step 1. The molar ratio of the intermediate III to the diaminophthalonitrile compound is 1:(0.8-1.5), preferably 1:(1-1.2).

[0146] The reaction solvent is an ether solvent or an organic acid solvent, preferably an organic acid solvent, more preferably acetic acid. The molar volume ratio of the intermediate III to the solvent is 2 mmol:(15-25) mL, preferably 2 mmol:(18-20) mL.

[0147] The post-treatment is to neutralize with an alkali metal weak acid salt, extract with dichloromethane to obtain an organic phase, dry the organic phase to remove the solvent, obtain a crude product, and purify it by column chromatography using a mixed solvent of petroleum ether and dichloromethane as an eluent.

[0148] When reactant II is an aromatic phosphine oxide compound, the method further comprises:

[0149] Step 3: Add the intermediate II and the aromatic amine compound III into a solvent and reflux to obtain a dicyanoquinoxaline compound.

[0150] The aromatic amine compound III is a primary amine, a secondary amine or an aromatic amine-based boric acid pinacol ester, preferably aniline, diphenylamine or triphenylamine-4-boric acid pinacol ester, more preferably diphenylamine or triphenylamine-4-boric acid pinacol ester.

[0151] The molar ratio of the intermediate II to the aromatic amine compound III is 2:(1-7), preferably 2:(2-6), and more preferably 2:(2.5-5).

[0152] The reaction is carried out in the presence of a catalyst, the catalyst is selected from a palladium catalyst, preferably selected from an organic palladium, more preferably tetrakistriphenylphosphine palladium or tris dibenzylideneacetone dipalladium. The molar ratio of the intermediate II to the catalyst is 1:(0.01-0.05), preferably 1:(0.02-0.04), more preferably 1:0.03. Preferably, when a non-palladium phosphine complex is used as a catalyst, an organic phosphine is added to assist the catalysis, such as adding tri-tert-butyl phosphine and tris dibenzylideneacetone dipalladium. The molar ratio of the organic phosphine to the catalyst palladium is (20-40):6, preferably (28-32):6.

[0153] The reaction is carried out in the presence of an alkaline substance, the base is selected from an alkali metal weak acid salt or an organic base, preferably selected from an alkali metal weak acid salt, more preferably potassium carbonate or cesium carbonate. The molar ratio of the intermediate II to the base is 1:(1-5), preferably 1:(2-4), more preferably 1:3.

[0154] The solvent is selected from one or more of an alcohol solvent, an ether solvent, an aromatic hydrocarbon solvent and water, preferably one or more of methanol, ethanol, toluene, xylene, tetrahydrofuran and water, more preferably one or more of xylene, tetrahydrofuran and water. The molar volume ratio of the intermediate product II to the solvent is 2 mmol: (6-14 mL), preferably 2 mmol: (8-12 mL).

[0155] The reaction temperature is 60-160°C, preferably 70-150°C, more preferably 80-140°C; the reaction time is 8-16h, preferably 10-14h.

[0156] After the reaction is completed, ice water is poured into the reaction solution, and the reaction solution is post-treated to obtain a cyanoquinoxaline red photothermal excitation delayed fluorescent material, such as compound 9-compound 12. The post-treatment includes extraction, drying and purification. For example, extraction with water and dichloromethane, combining the organic layers, drying and removing the organic solvent to obtain a crude product, and column chromatography purification is performed using a mixed solvent of petroleum ether and dichloromethane as an eluent.

[0157] The invention provides an electro-induced red light device prepared by utilizing a cyanoquinoxaline type red light thermally excited delayed fluorescence material.

[0158] The electro-red light device comprises a substrate layer, a conductive anode 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 conductive layer.

[0159] In the present invention, the preparation method of the light-emitting device using the cyanoquinoxaline red photothermally excited delayed fluorescent material as the main material of the light-emitting layer specifically comprises the following steps:

[0160] 1. preparing an anode conductive layer;

[0161] The conductive anode layer is prepared on the substrate layer. The conductive anode layer is selected from tin oxide conductive glass (ITO), transparent conductive polymers such as polyaniline, and semi-transparent metals such as Au, preferably ITO or semi-transparent metals, more preferably ITO. Preferably, the conductive anode layer is evaporated by vacuum evaporation.

[0162] Preferably, the vacuum degree of vacuum evaporation is 1×10 -6mbar, the evaporation rate is set to 0.1-0.3 nm / s, the evaporation material is indium tin oxide on the glass or plastic substrate, and the thickness of the conductive layer is 1-100 nm, preferably 5-15 nm, more preferably 6-10 nm, such as 6 nm.

[0163] Preferably, the following hole injection layer, hole transport layer, light emitting layer, electron transport layer, electron injection layer and cathode conductive layer are prepared by vacuum evaporation method.

[0164] 2. preparing a hole injection layer;

[0165] The hole injection layer is evaporated on the anode conductive layer, and the evaporated thickness is 2 to 20 nm, preferably 4 to 15 nm, more preferably 5 to 10 nm, such as 6 nm.

[0166] The hole injection layer material is selected from molybdenum oxide or poly (3,4-ethylenedioxythiophene): polystyrene sulfonate) (PEDOT:PSS), preferably molybdenum oxide, more preferably molybdenum oxide.

[0167] 3. Preparation of hole transport layer;

[0168] The hole transport layer is evaporated on the hole injection layer, and the evaporated thickness is 30-90 nm, preferably 40-80 nm, more preferably 50-70 nm, such as 60 nm.

[0169] The hole transport layer material is selected from 9,9'-(1,3-phenyl)di-9H-carbazole (mCP) or bis[2-((oxy)diphenylphosphino)phenyl]ether (DPEPO), preferably 9,9'-(1,3-phenyl)di-9H-carbazole (mCP).

[0170] 4. preparing a light-emitting layer;

[0171] The light-emitting layer is evaporated on the hole transport layer, and the evaporated thickness is 10-50 nm, preferably 15-45 nm, more preferably 20-40 nm, such as 30 nm.

[0172] The light-emitting layer material is a mixture of a cyanoquinoxaline red light-heat-excited delayed fluorescent material and 4,4'-di(9-carbazole)biphenyl (CBP).

[0173] 5. preparing an electron transport layer;

[0174] The electron transport layer is evaporated on the hole blocking layer, and the evaporated thickness is 20-90 nm, preferably 25-80 nm, more preferably 30-70 nm, such as 60 nm.

[0175] The electron transport layer material is 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl) (TPBi).

[0176] 6. preparing an electron injection layer;

[0177] The electron injection layer is evaporated on the electron transport layer, and the evaporated thickness is 1-10 nm, preferably 1-5 nm, more preferably 1-3 nm, such as 1 nm.

[0178] The electron injection layer material is selected from lithium tetrakis(8-hydroxyquinoline)borate (LiBq4) or LiF, preferably LiF.

[0179] 7. Prepare a cathode conductive layer, encapsulate it, and obtain a thermally excited delayed fluorescence electroluminescent red light device.

[0180] The cathode conductive layer is evaporated on the electron injection layer, and the evaporated thickness is 1-105nm.

[0181] The cathode conductive layer material is selected from a single metal cathode or an alloy cathode, such as calcium, magnesium, silver, aluminum, calcium alloy, magnesium alloy, silver alloy or aluminum alloy.

[0182] The cyanoquinoxaline red photothermal excited delayed fluorescence material prepared in the present invention effectively weakens the interaction between molecules through molecular structure design, thereby suppressing the quenching effect when the material is used as a light-emitting layer material of an electroluminescent device, thereby improving various performances of the electroluminescent device.

[0183] Example

[0184] Example 1

[0185] Mix 10 mmol of 4,5-diaminophthalonitrile, 10 mmol of 2-bromo-1-(4-bromophenyl)ethan-1-one, 50 ml of water and 0.9 g of hexadecyltrimethylammonium bromide, stir and react at 100 ° C for 12 hours, then pour into ice water, filter, and wash the obtained solid with anhydrous ethanol to obtain 2-(4-bromophenyl)quinoxaline-6,7-dicarbonitrile.

[0186] 2mmol 2-(4-bromophenyl)quinoxaline-6,7-dicarbonitrile was mixed with 2.5mmol diphenylamine, 0.06mmol tridibenzylideneacetone dipalladium, 6mmol cesium carbonate, and 0.3mmol tri-tert-butylphosphine, and 10mL xylene was added as solvent. The mixture was refluxed at 135°C for 12h, and then poured into ice water. The mixture was extracted with water and dichloromethane (the volume ratio of the two was 1:1), the organic layers were combined, and the organic solvent was removed after drying to obtain a crude product, which was purified by column chromatography using a mixed solvent of petroleum ether and dichloromethane as an eluent (the volume ratio of the two was 1:2) to obtain a cyano-substituted quinoxaline red photothermal excitation delayed fluorescent material 2-(4-(diphenylamino)phenyl)quinoxaline-6,7-dicarbonitrile (compound 1).

[0187] The obtained compound 1 was subjected to H NMR spectrum analysis, and the test data were as follows: 1 H NMR (TMS, CDCl3, 400MHz): δ = 9.45 (s, 1H), 8.52 (s, 1H), 8.51 (s, 1H), 8.12 (d, J = 8.6Hz, 2H), 7.36 (t, J = 7.6Hz, 4H), 7.23–7.14 (m, 8H).

[0188] Thermogravimetric analysis of the obtained compound 1 revealed that the pyrolysis temperature of the obtained compound 1 was 428°C.

[0189] The obtained mixture of compound 1 and CBP (wherein the mass fraction of compound 1 is 20%) is used as the guest material of the light-emitting layer to prepare an electroluminescent red light device, and the method is as follows:

[0190] 1. Place the glass or plastic substrate washed with deionized water into a vacuum evaporator for evaporation at a vacuum degree of 1×10 -6 mbar, and the evaporation rate was set to 0.1 nm s -1 , the evaporation material is indium tin oxide, and the anode conductive layer with a thickness of 6nm is obtained;

[0191] 2. Vapor-depositing the hole injection layer material MoOx on the anode conductive layer to obtain a hole injection layer with a thickness of 6 nm;

[0192] 3. Vapor depositing the hole transport layer material mCP on the hole injection layer to obtain a hole transport layer with a thickness of 60 nm;

[0193] 4. Evaporating the light-emitting layer material on the hole transport layer: a mixture of compound I and CBP, wherein the mass fraction of compound I is 20%, to obtain a light-emitting layer with a thickness of 30 nm;

[0194] 5. Continue to evaporate TPBi on the light-emitting layer to obtain an electron transport layer with a thickness of 60 nm;

[0195] 6. Vapor depositing electron injection layer material LiF on the electron transport layer, with a thickness of 1 nm;

[0196] 7. A cathode conductive layer with a thickness of 100 nm and a material of aluminum is evaporated on the electron injection layer to obtain an electroluminescent red light device.

[0197] The structure of the electroluminescent red light device in this embodiment is: ITO / MoO3 (6nm) / mCP (60nm) / CBP: Compound 1 (20%) 30nm / TPBi (60nm) / LiF (1nm) / Al (100nm).

[0198] In Example 1, the variation trend of the current density of the electro-red light device with the change of voltage was tested, and it was found that compound 1 had semiconductor characteristics, and its threshold voltage was 2.8V.

[0199] In Example 1, the brightness of the electro-red light device was tested as the voltage changed, and the maximum brightness of the device was found to be 22460 cd·m -2 .

[0200] In Example 1, the current efficiency of the electro-red light device was tested as the brightness changed, and the device was found to have a current efficiency of 1.96 cd·m -2 When the current efficiency reaches the maximum value of 38.78cd·A -1 .

[0201] In Example 1, the power efficiency of the electro-red light device was tested as the brightness changed, and it was found that the device had a power efficiency of 1.96 cd·m -2 When the power efficiency reaches the maximum value of 43.49lm·W -1 .

[0202] In Example 1, the external quantum efficiency of the electro-red light device was tested for the change in current density, and the device was found to have a brightness of 1.96 cd·m -2 The maximum external quantum efficiency of 21.5% was obtained.

[0203] In Example 1, the electroluminescence spectrum of the electroluminescent red light device is as follows: Figure 5 As shown by Figure 5 It can be seen that the electroluminescence peak of the device is at 604nm.

[0204] Example 2

[0205] According to the synthesis method of compound 1 in Example 1, compound 2 was prepared, except that 4,5-diaminophthalonitrile was replaced by 2,3-diaminoterephthalonitrile.

[0206] The obtained compound 2 was subjected to H NMR spectrum analysis, and the test data were as follows: 1 H NMR (TMS, CDCl3, 400MHz): δ = 9.54 (s, 1H), 8.24 (d, J = 8.9Hz, 2H), 8.16 (d, J = 7.6Hz, 1H ),8.07(d,J=7.6Hz,1H),7.37(t,J=7.9Hz,4H),7.25–7.21(m,4H),7.21–7.16(m,4H).

[0207] The obtained compound IV was subjected to thermogravimetric analysis, and the test data are as follows: Figure 4 As shown by Figure 4It can be seen that the cracking temperature of the obtained compound is 422°C.

[0208] According to the preparation method of the electro-red light emitting device in Example 1, the electro-red light emitting device was prepared by using a mixture of compound 2 and CBP (wherein the mass fraction of compound 2 was 20%) as the light emitting layer material.

[0209] The structure of the electroluminescent device in this embodiment is: ITO / MoO3 (6nm) / mCP (60nm) / CBP: Compound 2 (20%) (30nm) / TPBi (60nm) / LiF (1nm) / Al (100nm).

[0210] In Example 2, the variation trend of the current density of the electro-red light device with the change of voltage was tested, and it was found that compound 2 had semiconductor characteristics, and its threshold voltage was 3.0V.

[0211] In Example 2, the brightness of the electro-red light device was tested as a function of voltage, and the maximum brightness of the device was found to be 4361 cd·m -2 .

[0212] In Example 2, the current efficiency of the electro-red light device was tested as the brightness changed, and the device was found to have a -2 When the current efficiency reaches the maximum value of 7.1cd·A -1 .

[0213] In Example 2, the power efficiency of the electro-red light device was tested as the brightness changed, and the device was found to have a power efficiency of 3.0 cd·m -2 When the power efficiency reaches the maximum value of 7.4lm·W -1 .

[0214] In Example 2, the external quantum efficiency of the electro-red light device was tested for the change in current density, and the device was found to have a brightness of 3.0 cd·m -2 When , the maximum external quantum efficiency of 20.6% was obtained.

[0215] In Example 2, the electroluminescence spectrum of the electroluminescent red light device is as follows: Figure 6 As shown by Figure 6 It can be seen that the electroluminescence peak of the device is at 668nm.

[0216] Example 3

[0217] According to the method in Example 1, 2-(4-bromophenyl)quinoxaline-6,7-dicarbonitrile was synthesized.

[0218] 2mmol of 2-(4-bromophenyl)quinoxaline-6,7-dicarbonitrile was mixed with 2.5mmol of triphenylamine-4-boronic acid pinacol ester, 0.06mmol of tetratriphenylphosphine palladium, and 6mmol of potassium carbonate, and 10mL of tetrahydrofuran and water were added as solvents in a volume ratio of 3:1. The mixture was refluxed at 80°C for 12h, and then poured into ice water. The mixture was extracted with water and dichloromethane (the volume ratio of the two was 1:1), the organic layers were combined, and the organic solvent was removed after drying to obtain a crude product, which was purified by column chromatography using a mixed solvent of petroleum ether and dichloromethane as an eluent (the volume ratio of the two was 1:2) to obtain a cyano-substituted quinoxaline red photothermally excited delayed fluorescent material 2-(4'-(diphenylamino)-[1,1'-biphenyl]-4-yl)quinoxaline-6,7-dicarbonitrile, i.e., compound 3.

[0219] The obtained compound 3 was subjected to H NMR spectrum analysis, and the test data were as follows: 1 H NMR (TMS, CDCl3, 400MHz): δ = 9.95 (s, 1H), 8.88 (s, 1H), 8.84 (d, J = 2.9Hz, 2H), 8.78 (s, 1H), 7.89 (d, J = 15.0Hz, 2H), 7. 55(d,J=15.0Hz,2H),7.37(d,J=15.0Hz,2H),7.24(t,J=15.0Hz,4H),7.08(d,J=15.3Hz,4H),7.00(t,J=14.7Hz,2H).

[0220] The obtained compound 3 was subjected to thermogravimetric analysis, and the test data are as follows: Figure 4 As shown by Figure 4 It can be seen that the cracking temperature of the obtained compound is 409°C.

[0221] According to the preparation method of the electro-red light emitting device in Example 1, the electro-red light emitting device was prepared by using a mixture of compound 3 and CBP (wherein the mass fraction of compound 3 was 20%) as the light emitting layer material.

[0222] The structure of the electroluminescent device in this embodiment is: ITO / MoO3 (6nm) / mCP (60nm) / CBP: Compound 3 (20%) (30nm) / TPBi (60nm) / LiF (1nm) / Al (100nm).

[0223] In Example 3, the variation trend of the current density of the electro-red light device with the change of voltage was tested, and it was found that compound 3 had semiconductor characteristics, and its threshold voltage was 2.81V.

[0224] In Example 3, the brightness of the electro-red light device was tested as a function of voltage, and the maximum brightness of the device was found to be 25650 cd·m -2.

[0225] In Example 3, the current efficiency of the electro-red light device was tested as the brightness changed, and it was found that the device had a brightness of 2.81 cd·m -2 When the current efficiency reaches the maximum value of 46.9cd·A -1 .

[0226] In Example 3, the power efficiency of the electro-red light device was tested as the brightness changed, and the device was found to have a power efficiency of 2.81 cd·m -2 When the power efficiency reaches the maximum value of 52.5lm·W -1 .

[0227] In Example 3, the external quantum efficiency of the electro-red light device was tested for the change in current density, and the device was found to have a brightness of 2.81 cd·m -2 The maximum external quantum efficiency of 25.4% was obtained.

[0228] In Example 3, the electroluminescence spectrum of the electroluminescent red light device is as follows: Figure 7 As shown by Figure 7 It can be seen that the electroluminescence peak of the device is at 604nm.

[0229] Example 4

[0230] According to the synthesis method of compound 3 in Example 3, compound 4 was prepared. The only difference was that 4,5-diaminophthalonitrile was replaced by 2,3-diaminoterephthalonitrile. The obtained compound 4 was analyzed by hydrogen nuclear magnetic resonance spectrum, and the test data was: 1 H NMR (TMS, CDCl3, 400MHz): δ = 9.66 (s, 1H), 8.44 (d, J = 8.5Hz, 2H), 8.22 (d, J = 7.6Hz, 1H), 8.15 (d, J = 7.6Hz, 1H), 7.83(d,J=8.5Hz,2H),7.58(d,J=8.6Hz,2H),7.30(t,J=7.9Hz,4H),7.21–7.13(m,6H),7.08(t,J=7.3Hz,2H).

[0231] Thermogravimetric analysis of the obtained compound 4 revealed that the pyrolysis temperature of the obtained compound was 401°C.

[0232] According to the preparation method of the electro-red light emitting device in Example 1, the electro-red light emitting device was prepared by using a mixture of compound 4 and CBP (wherein the mass fraction of compound 4 was 20%) as the light emitting layer material.

[0233] The structure of the electroluminescent device in this embodiment is: ITO / MoO3 (6nm) / mCP (60nm) / CBP: Compound 4 (20%) (30nm) / TPBi (60nm) / LiF (1nm) / Al (100nm).

[0234] In Example 4, the variation trend of the current density of the electro-red light device with the change of voltage was tested, and it was found that compound 4 had semiconductor characteristics, and its threshold voltage was 2.96V.

[0235] In Example 4, the brightness of the electro-red light device was tested as the voltage changed, and the maximum brightness of the device was found to be 1832 cd·m -2 .

[0236] In Example 4, the current efficiency of the electro-red light device was tested as the brightness changed, and it was found that the device had a brightness of 2.08 cd·m -2 When the current efficiency reaches the maximum value of 8.65cd·A -1 .

[0237] In Example 4, the power efficiency of the electro-red light device was tested as the brightness changed, and the device was found to have a power efficiency of 2.08 cd·m -2 When the power efficiency reaches the maximum value of 9.05lm·W -1 .

[0238] In Example 4, the external quantum efficiency of the electro-red light device was tested for the change in current density, and the device was found to have a brightness of 2.08 cd·m -2 The maximum external quantum efficiency of 23.1% was obtained.

[0239] In Example 4, the electroluminescence spectrum of the electroluminescent red light device is as follows: Figure 8 As shown by Figure 8 It can be seen that the electroluminescence peak of the device is at 664nm.

[0240] Example 5

[0241] 2mmol 1,2-bis(4-bromophenyl)ethane-1,2-dione was mixed with 4.5mmol diphenylamine, 0.1mmol tridibenzylideneacetone dipalladium, 12mmol cesium carbonate, and 0.6mmol tri-tert-butylphosphine, and 10mL xylene was added as solvent. The mixture was refluxed at 135°C for 12h, and then poured into ice water. The mixture was extracted with water and dichloromethane (the volume ratio of the two was 1:1), the organic layers were combined, and the organic solvent was removed after drying to obtain a crude product, which was purified by column chromatography using a mixed solvent of petroleum ether and dichloromethane as an eluent (the volume ratio of petroleum ether and dichloromethane was 1:2) to obtain 1,2-bis(4-(diphenylamino)phenyl)ethane-1,2-dione.

[0242] 2mmol of 1,2-bis(4-(diphenylamino)phenyl)ethane-1,2-dione and 2mmol of 4,5-diaminophthalonitrile were dissolved in 20ml of glacial acetic acid solution and refluxed at 118°C for 12 hours. Then, ice water was poured in and the mixture was neutralized with sodium bicarbonate solution. The crude product was extracted with dichloromethane and dried, and then the organic solvent was removed to obtain a crude product. The crude product was purified by column chromatography using a mixed solvent of petroleum ether and dichloromethane (the volume ratio of the two was 1:3) as an eluent to obtain a cyano-substituted quinoxaline red photothermally excited delayed fluorescent material 2,3-bis(4-(diphenylamino)phenyl)quinoxaline-6,7-dicarbonitrile, i.e., compound 5.

[0243] The obtained compound 5 was tested by UV spectrum and fluorescence spectrum. The test spectrum is as follows: Figure 1 shown.

[0244] The obtained compound 5 was subjected to H NMR spectrum analysis, and the test data were as follows: 1 H NMR (TMS, CDCl3, 400MHz): δ = 8.47 (s, 2H), 7.50 (d, J = 8.4Hz, 4H), 7.29 (t, J = 7.8Hz, 8H), 7.15 (d, J = 8Hz, 8H), 7.11 (t, J = 7.2Hz, 4H), 7.00 (d, J = 8.4Hz, 4H).

[0245] The obtained compound 5 was subjected to thermogravimetric analysis, and the test data were as follows: Figure 2 As shown by Figure 2 It can be seen that the cracking temperature of the obtained compound is 457°C.

[0246] According to the preparation method of the electro-red light emitting device in Example 1, the electro-red light emitting device was prepared by using a mixture of compound 5 and CBP (wherein the mass fraction of compound 5 was 20%) as the light emitting layer material.

[0247] The structure of the electroluminescent device in this embodiment is: ITO / MoO3 (6nm) / mCP (60nm) / CBP: Compound 5 (20%) (30nm) / TPBi (60nm) / LiF (1nm) / Al (100nm).

[0248] In Example 5, the variation trend of the current density of the electro-red light device with the change of voltage was tested, and it was found that compound 5 had semiconductor characteristics, and its threshold voltage was 2.69V.

[0249] In Example 5, the brightness of the electro-red light device was tested to determine the variation trend of the voltage, and the maximum brightness of the device was found to be 24160 cd·m -2 .

[0250] In Example 5, the current efficiency of the electro-red light device was tested as the brightness changed, and the device was found to have a -2 When the current efficiency reaches the maximum value of 42.7cd·A -1 .

[0251] In Example 5, the power efficiency of the electro-red light device was tested as the brightness changed, and the device was found to have a power efficiency of 2.69 cd·m -2 When the current efficiency reaches the maximum value of 49.9cd·A -1 .

[0252] In Example 5, the external quantum efficiency of the electro-red light device was tested for the change in current density, and the device was found to have a brightness of 2.69 cd·m -2 When , the maximum external quantum efficiency of 22.4% is obtained.

[0253] In Example 5, the electroluminescence spectrum of the electroluminescent red light device is as follows: Fig. 9 As shown by Fig. 9 It can be seen that the electroluminescence peak of the device is at 600nm.

[0254] Example 6

[0255] According to the synthesis method of compound 5 in Example 5, compound 6 was prepared, except that 4,5-diaminophthalonitrile was replaced by 2,3-diaminoterephthalonitrile.

[0256] The obtained compound 6 was tested by UV spectrum and fluorescence spectrum. The test spectrum is as follows: Figure 3 shown.

[0257] The obtained compound 6 was subjected to H NMR spectrum analysis, and the test data were: 1 H NMR (TMS, CDCl3, 400MHz): δ = 8.03 (s, 2H), 7.63 (d, J = 8.8Hz, 4H), 7.29 (t, J = 7. 8Hz, 8H), 7.16 (d, J = 7.6Hz, 8H), 7.11 (t, J = 7.2Hz, 4H), 6.99 (d, J = 8.8Hz, 4H).

[0258] The obtained compound 6 was subjected to thermogravimetric analysis, and the test data were as follows: Figure 4 As shown by Figure 4 It can be seen that the cracking temperature of the obtained compound is 436°C.

[0259] The electro-red light emitting device was prepared according to the preparation method of the electro-red light emitting device in Example 1, with a mixture of compound 6 and CBP (wherein the mass fraction of compound 6 was 20%) as the light emitting layer material.

[0260] The structure of the electroluminescent device in this embodiment is: ITO / MoO3 (6nm) / mCP (70nm) / CBP: Compound 6 (20%) (30nm) / TPBi (60nm) / LiF (1nm) / Al (100nm).

[0261] In Example 6, the variation trend of the current density of the electro-red light device with the change of voltage was tested, and it was found that compound 6 had semiconductor characteristics, and its threshold voltage was 2.68V.

[0262] In Example 6, the brightness of the electro-red light device was tested as a function of voltage, and the maximum brightness of the device was found to be 2823 cd·m -2 .

[0263] In Example 6, the current efficiency of the electro-red light device was tested as the brightness changed, and it was found that the device had a brightness of 3.26 cd·m -2 When the current efficiency reaches the maximum value of 9.59cd·A -1 .

[0264] In Example 6, the power efficiency of the electro-red light device was tested as the brightness changed, and the device was found to have a power efficiency of 3.26 cd·m -2 When the power efficiency reaches the maximum value of 9.87lm·W -1 .

[0265] In Example 6, the external quantum efficiency of the electro-red light device was tested for the change in current density, and the device was found to have a brightness of 3.26 cd·m -2 The maximum external quantum efficiency of 24.5% was obtained.

[0266] In Example 6, the electroluminescence spectrum of the electroluminescent red light device is as follows: Fig.10 As shown by Fig.10 It can be seen that the electroluminescence peak of the device is at 664nm.

[0267] Example 7

[0268] 1,2-bis(4-bromophenyl)ethane-1,2-dione was prepared according to the method in Example 5.

[0269] 2mmol 1,2-bis(4-bromophenyl)ethane-1,2-dione was mixed with 4.5mmol triphenylamine-4-boronic acid pinacol ester, 0.1mmol tetrakistriphenylphosphine palladium, and 12mmol potassium carbonate, and 10mL tetrahydrofuran and water were added as solvents (the volume ratio of the two was 3:1), and the mixture was refluxed at 80°C for 12h, and then poured into ice water. The mixture was extracted with water and dichloromethane (the volume ratio of the two was 1:1), and the organic layers were combined, dried, and then the organic solvent was removed to obtain a crude product, which was purified by retrograde column chromatography using a mixed solvent of petroleum ether and dichloromethane as an eluent (the volume ratio of the two was 1:2) to obtain 1,2-bis(4'-(diphenylamino)-[1,1'-biphenyl]-4-yl)ethane-1,2-dione (Intermediate III).

[0270] 2mmol of 1,2-bis(4'-(diphenylamino)-[1,1'-biphenyl]-4-yl)ethane-1,2-dione and 2mmol of 4,5-diaminophthalonitrile were dissolved in 20ml of glacial acetic acid solution and refluxed at 118°C for 12 hours. Then, ice water was poured in and the pH value was neutralized with sodium bicarbonate solution to about 7. The crude product was extracted with dichloromethane, dried and then the organic solvent was removed to obtain a crude product, which was purified by column chromatography using a mixed solvent of petroleum ether and dichloromethane (the volume ratio of the two was 1:3) as an eluent to obtain a cyano-substituted quinoxaline red photothermally excited delayed fluorescent material 2,3-bis(4'-(diphenylamino)-[1,1'-biphenyl]-4-yl)quinoxaline-6,7-dicarbonitrile, i.e., compound 7.

[0271] The obtained compound 7 was subjected to H NMR spectrum analysis, and the test data were: 1 H NMR (TMS, CDCl3, 400MHz): δ = 8.62 (s, 2H), 7.69 (d, J = 8.3Hz, 4H), 7.62 (d, J = 8.3Hz, 4H ),7.51(d,J=8.5Hz,4H),7.28(t,8H),7.14(d,J=8.1Hz,12H),7.06(t,J=7.3Hz,4H).

[0272] Thermogravimetric analysis of the obtained compound 7 revealed that the pyrolysis temperature of the obtained compound 7 was 433°C.

[0273] According to the preparation method of the electro-red light emitting device in Example 1, the electro-red light emitting device was prepared by using a mixture of compound 7 and CBP (wherein the mass fraction of compound 7 was 20%) as the light emitting layer material.

[0274] The structure of the electroluminescent device in this embodiment is: ITO / MoO3 (6nm) / mCP (60nm) / CBP: Compound 7 (20%) (30nm) / TPBi (60nm) / LiF (1nm) / Al (100nm)

[0275] The variation trend of the current density of the electro-red light device tested in Example 7 with the change of voltage shows that compound 7 has semiconductor properties, and its threshold voltage is 2.81V.

[0276] In Example 7, the brightness of the electro-red light device was tested as a function of voltage, and the maximum brightness of the device was found to be 21950 cd·m -2 .

[0277] In Example 7, the current efficiency of the electro-red light device was tested as the brightness changed, and it was found that the device had a brightness of 2.81 cd·m -2 When the current efficiency reaches the maximum value of 47.5cd·A -1 .

[0278] In Example 7, the power efficiency of the electro-red light device was tested as the brightness changed, and it was found that the device had a power efficiency of 2.81 cd·m -2 When the power efficiency reaches the maximum value of 53.1lm·W -1 .

[0279] In Example 7, the external quantum efficiency of the electroluminescent red light device was tested for the change in current density, and the device was found to have a brightness of 2.81 cd·m -2 When , the maximum external quantum efficiency of 29.5% is obtained.

[0280] In Example 7, the electroluminescence spectrum of the electroluminescent red light device is as follows: Fig.11 As shown, it can be seen from this figure that the electroluminescence peak of the device is at 608nm.

[0281] Example 8

[0282] According to the synthesis method of compound 7 in Example 7, compound 8 was prepared, except that 4,5-diaminophthalonitrile was replaced by 2,3-diaminoterephthalonitrile.

[0283] The obtained compound 8 was subjected to H NMR spectrum analysis, and the test data were as follows: 1 H NMR (TMS, CDCl3, 400MHz): δ = 8.16 (s, 2H), 7.82 (d, J = 8.3Hz, 4H), 7.61 (d, J = 8.3Hz, 4H ),7.52(d,J=8.6Hz,4H),7.28(t,8H),7.14(d,J=8.2Hz,12H),7.06(t,J=7.3Hz,4H).

[0284] The obtained compound 8 was subjected to thermogravimetric analysis, and the test data are as follows: Fig.16 As shown by Fig.16 It can be seen that the pyrolysis temperature of the obtained compound 8 is 426°C.

[0285] According to the preparation method of the electro-red light emitting device in Example 1, the electro-red light emitting device was prepared by using a mixture of compound 8 and CBP (wherein the mass fraction of compound 8 was 20%) as the light emitting layer material.

[0286] The structure of the electroluminescent device in this embodiment is: ITO / MoO3 (6nm) / mCP (60nm) / CBP: Compound 8 (20%) (30nm) / TPBi (60nm) / LiF (1nm) / Al (100nm).

[0287] In Example 8, the variation trend of the current density of the electro-red light device with the change of voltage was tested, and it was found that compound 8 had semiconductor characteristics, and its threshold voltage was 3.05V.

[0288] In Example 8, the brightness of the electro-red light device was tested as a function of voltage, and the maximum brightness of the device was found to be 5498 cd·m -2 .

[0289] In Example 8, the current efficiency of the electro-red light device was tested as the brightness changed, and it was found that the device had a brightness of 2.26 cd·m -2 When the current efficiency reaches the maximum value of 9.57cd·A -1 .

[0290] In Example 8, the power efficiency of the electro-red light device was tested as the brightness changed, and it was found that the device had a power efficiency of 2.26 cd·m -2 When the power efficiency reaches the maximum value of 9.85lm·W -1 .

[0291] In Example 8, the external quantum efficiency of the electroluminescent red light device was tested for the change in current density, and the device was found to have a brightness of 2.26 cd·m -2 The maximum external quantum efficiency of 21.6% was obtained.

[0292] In Example 8, the electroluminescence spectrum of the electroluminescent red light device is as follows: Fig.12 As shown, it can be seen from this figure that the electroluminescence peak of the device is at 660nm.

[0293] Example 9

[0294] Dissolve 2mmol 1,2-bis(4-bromophenyl)ethane-1,2-dione and 2mmol 4,5-diaminophthalonitrile in 20ml glacial acetic acid solution, and reflux for 12 hours at 118°C. Then pour into ice water and add sodium bicarbonate solution to neutralize to a pH value of about 7. Extract with dichloromethane, remove the organic solvent after drying, and obtain a crude product. Use a mixed solvent of petroleum ether and dichloromethane as an eluent and perform column chromatography purification (the volume ratio of petroleum ether to dichloromethane is 1:2) to obtain 2,3-bis(4-bromophenyl)quinoxaline-6,7-dicarbonitrile.

[0295] 2mmol of synthesized 2,3-bis(4-bromophenyl)quinoxaline-6,7-dicarbonitrile was mixed with 2mmol of diphenylphosphine chloride, 0.01mmol of palladium acetate, and 6mmol of potassium acetate, and 10mL of N,N-dimethylformamide was added as solvent, and the mixture was reacted at 130°C for 12h, and then poured into ice water. Extracted with dichloromethane, 2.2mmol of 30% hydrogen peroxide was added to the organic layer, and oxidized at -5°C for 5 hours. Extracted with water and dichloromethane (the volume ratio of the two was 1:1), the organic layers were combined, and the organic solvent was removed after drying to obtain a crude product, which was purified by column chromatography using a mixed solvent of petroleum ether and ethyl acetate as eluent (the volume ratio of the two was 8:1) to obtain 2-(4-bromophenyl)-3-(4-(diphenylphosphoryl)phenyl)quinoxaline-6,7-dicarbonitrile;

[0296] 2mmol of the synthesized product 2-(4-bromophenyl)-3-(4-(diphenylphosphoryl)phenyl)quinoxaline-6,7-dicarbonitrile was mixed with 2.5mmol of diphenylamine, 0.06mmol of tridibenzylideneacetone dipalladium, 6mmol of cesium carbonate, and 0.3mmol of tri-tert-butylphosphine, and 10mL of xylene was added as solvent. The mixture was refluxed at 135°C for 12h, and then poured into ice water. The mixture was extracted with water and dichloromethane (the volume ratio of the two was 1:1), the organic layers were combined, and the organic solvent was removed after drying to obtain a crude product, which was purified by column chromatography using a mixed solvent of petroleum ether and dichloromethane as an eluent (the volume ratio of the two was 1:2) to obtain a cyano-substituted quinoxaline red photothermally excited delayed fluorescent material 2-(4-(diphenylamino)phenyl)-3-(4-(diphenylphosphoryl)phenyl)quinoxaline-6,7-dicarbonitrile, i.e., compound 9.

[0297] The obtained compound 9 was subjected to H NMR spectrum analysis, and the test data were as follows: 1H NMR (TMS, CDCl3, 400MHz): δ = 8.87 (s, 2H), 8.53 (d, J = 12.0Hz, 2H), 8.29 (d, J = 12.0Hz, 2H), 8.01 (d, J = 12.0Hz, 2H), 7.81–7.7 3(m,4H),7.55–7.47(m,6H),7.41(d,J=12.0Hz,2H),7.24(t,J=12.0Hz,4H),7.08(d,J=12.2Hz,4H),7.00(t,J=11.8Hz,2H).

[0298] Thermogravimetric analysis of the obtained compound 9 revealed that the pyrolysis temperature of the obtained compound was 411°C.

[0299] According to the preparation method of the electro-red light emitting device in Example 1, the electro-red light emitting device was prepared by using a mixture of compound 9 and CBP (wherein the mass fraction of compound 9 was 20%) as the light emitting layer material.

[0300] The structure of the device is ITO / MoO3 (6nm) / mCP (60nm) / CBP: Compound 9 (20%) (30nm) / TPBi (60nm) / LiF (1nm) / Al (100nm).

[0301] In Example 9, the variation trend of the current density of the electro-red light device with the change of voltage was tested, and it was found that compound 9 had semiconductor characteristics, and its threshold voltage was 2.70V.

[0302] In Example 9, the brightness of the electro-red light device was tested to determine the variation trend of the voltage, and the maximum brightness of the device was found to be 16050 cd·m -2 .

[0303] In Example 9, the current efficiency of the electro-red light device was tested as the brightness changed, and it was found that the device had a brightness of 2.70 cd·m -2 When the current efficiency reaches the maximum value of 48.7cd·A -1 .

[0304] In Example 9, the power efficiency of the electro-red light device was tested as the brightness changed, and it was found that the device had a power efficiency of 2.70 cd·m -2 When the power efficiency reaches the maximum value of 56.6lm·W -1 .

[0305] In Example 9, the external quantum efficiency of the electro-red light device was tested for the change in current density, and the device was found to have a brightness of 2.70 cd·m -2 When , the maximum external quantum efficiency of 30.5% is obtained.

[0306] In Example 9, the electroluminescence spectrum of the electroluminescent red light device is as follows: Fig.13 As shown, it can be seen from this figure that the electroluminescence peak of the device is at 612nm.

[0307] Example 10

[0308] According to the synthesis method of compound 9 in Example 9, compound 10 was prepared, except that 4,5-diaminophthalonitrile was replaced by 2,3-diaminoterephthalonitrile.

[0309] The obtained compound 10 was subjected to H NMR spectrum analysis, and the test data were as follows: 1 H NMR (TMS, CDCl3, 400MHz): δ = 8.53 (d, J = 12.0Hz, 2H), 8.29 (d, J = 6Hz, 4H), 8.01 (d, J = 12.0Hz, 2H), 7.82–7.73 (m, 4H) ,7.55–7.47(m,6H),7.41(d,J=12.0Hz,2H),7.24(t,J=12.0Hz,4H),7.08(d,J=12.2Hz,4H),7.00(t,J=11.8Hz,2H).

[0310] Thermogravimetric analysis of the obtained compound 10 revealed that the pyrolysis temperature of the obtained compound was 401°C.

[0311] According to the preparation method of the electro-red light emitting device in Example 1, an electro-red light emitting device was prepared using a mixture of compound 10 and CBP (wherein the mass fraction of compound 10 was 20%) as the light emitting layer material.

[0312] The structure of the device is ITO / MoO3 (6nm) / mCP (60nm) / CBP: Compound 10 (20%) (30nm) / TPBi (60nm) / LiF (1nm) / Al (100nm)

[0313] In Example 10, the variation trend of the current density of the electro-red light device with the change of voltage was tested, and it was found that compound 10 had semiconductor characteristics, and its threshold voltage was 3.0V.

[0314] In Example 10, the brightness of the electro-red light device was tested to determine the variation trend of the voltage, and the maximum brightness of the device was found to be 5833 cd·m -2 .

[0315] In Example 10, the current efficiency of the electro-red light device was tested as the brightness changed. It was found that the device had a brightness of 3.0 cd·m -2 When the current efficiency reaches the maximum value of 8.6cd·A-1 .

[0316] In Example 10, the power efficiency of the electro-red light device was tested as the brightness changed, and the device was found to have a power efficiency of 3.0 cd·m -2 When the power efficiency reaches the maximum value of 9.0lm·W -1 .

[0317] In Example 10, the external quantum efficiency of the electro-red light device was tested for the change trend of the current density, and the device was found to have a brightness of 3.0 cd·m -2 The maximum external quantum efficiency of 23.1% was obtained.

[0318] In Example 10, the electroluminescence spectrum of the electroluminescent red light device is as follows: Fig.14 As shown, it can be seen from this figure that the electroluminescence peak of the device is at 664nm.

[0319] Embodiment 11

[0320] According to the method in Example 9, 2-(4-bromophenyl)-3-(4-(diphenylphosphoryl)phenyl)quinoxaline-6,7-dicarbonitrile was synthesized.

[0321] Mix 2mmol of 2-(4-bromophenyl)-3-(4-(diphenylphosphoryl)phenyl)quinoxaline-6,7-dicarbonitrile with 2.5mmol of triphenylamine-4-boric acid pinacol ester, 0.06mmol of tetrakistriphenylphosphine palladium, and 6mmol of potassium carbonate, add 10mL of tetrahydrofuran and water as solvents (the volume ratio of the two is 3:1), reflux at 80°C for 12h, and then pour into ice water. The mixture was extracted with water and dichloromethane (the volume ratio of the two was 1:1), the organic layers were combined, and the organic solvent was removed after drying to obtain a crude product, which was purified by column chromatography using a mixed solvent of petroleum ether and dichloromethane as an eluent (the volume ratio of the two was 1:3) to obtain a cyano-substituted quinoxaline-based red photothermal excited delayed fluorescent material 2-(4'-(diphenylamino)-[1,1'-biphenyl]-4-yl)-3-(4-(diphenylphosphoryl)phenyl)quinoxaline-6,7-dicarbonitrile, i.e., compound 11.

[0322] The obtained compound 11 was subjected to H NMR spectrum analysis, and the test data were as follows: 1H NMR (TMS, CDCl3, 400MHz): δ = 8.86 (d, J = 13.8Hz, 4H), 8.53 (d, J = 12.0Hz, 2H), 8.01 (d, J = 12.0Hz, 2H), 7.89 (d, J = 12.0Hz, 2H), 7.82 –7.74(m,4H),7.58–7.47(m,8H),7.37(d,J=12.0Hz,2H),7.24(t,J=12.0Hz,4H),7.08(d,J=12.2Hz,4H),7.00(t,J=11.8Hz,2H).

[0323] Thermogravimetric analysis of the obtained compound 11 revealed that the pyrolysis temperature of the obtained compound was 398°C.

[0324] According to the preparation method of the electro-red light emitting device in Example 1, an electro-red light emitting device was prepared using a mixture of compound 11 and CBP (wherein the mass fraction of compound 11 was 20%) as the light emitting layer material.

[0325] The structure of the device is ITO / MoO3 (6nm) / mCP (60nm) / CBP: Compound 11 (20%) (30nm) / TPBi (60nm) / LiF (1nm) / Al (100nm)

[0326] In Example 11, the voltage-current density relationship curve of the electroluminescent red light device is as follows: Fig.17 As shown by Fig.17 It can be seen that compound 11 has semiconductor properties and its threshold voltage is 2.80V.

[0327] In Example 11, the voltage-brightness relationship curve of the electroluminescent red light device is as follows: Fig.18 As shown in the figure, the maximum brightness of the device can reach 21890cd·m -2 .

[0328] In Example 11, the brightness-current efficiency relationship curve of the electroluminescent red light device is as follows: Fig.19 As shown by Fig.19 It can be seen that the device has a brightness of 2.80cd·m -2 When the current efficiency reaches the maximum value of 52.6cd·A -1 .

[0329] In Example 11, the brightness-power efficiency relationship curve of the electro-red light device is as follows: Fig. 20 As shown by Fig. 20 It can be seen that the device has a brightness of 2.80cd·m -2 When the power efficiency reaches the maximum value of 59.0lm·W -1 .

[0330] In Example 11, the current density-external quantum efficiency relationship curve of the electroluminescent red light device is as follows: Fig.21 As shown by Fig.21 It can be seen that the device has a brightness of 2.80cd·m -2 The maximum external quantum efficiency of 31.4% was obtained.

[0331] In Example 11, the electroluminescence spectrum of the electroluminescent red light device is as follows: Fig.15 As shown, it can be seen from this figure that the electroluminescence peak of the device is at 612nm.

[0332] Example 12

[0333] According to the synthesis method of compound 11 in Example 11, compound 12 was prepared. The only difference was that 2-(4-bromophenyl)-3-(4-(diphenylphosphoryl)phenyl)quinoxaline-6,7-dicarbonitrile was replaced by 2-(4-bromophenyl)-3-(4-(diphenylphosphoryl)phenyl)quinoxaline-5,8-dicarbonitrile.

[0334] The obtained compound 12 was subjected to H NMR spectrum analysis, and the test data were as follows: 1 H NMR (TMS, CDCl3, 400MHz): δ = 8.86 (d, J = 12.0Hz, 2H), 8.53 (d, J = 12.0Hz, 2H), 8.29 (s, 2H), 8.01 (d, J = 12.0Hz, 2H), 7.89 (d, J = 12.0Hz, 2H) ),7.82–7.73(m,4H),7.58–7.46(m,8H),7.37(d,J=12.0Hz,2H),7.24(t,J=12.0Hz,4H),7.08(d,J=12.2Hz,4H),7.00(t,J=11.8Hz,2H).

[0335] Thermogravimetric analysis of the obtained compound 12 revealed that the pyrolysis temperature of the obtained compound was 390°C.

[0336] According to the preparation method of the electro-red light emitting device in Example 1, an electro-red light emitting device was prepared using a mixture of compound 12 and CBP (wherein the mass fraction of compound 11 was 20%) as the light emitting layer material.

[0337] The structure of the device is ITO / MoO3 (6nm) / mCP (60nm) / CBP: Compound 12 (20%) (30nm) / TPBi (60nm) / LiF (1nm) / Al (100nm)

[0338] In Example 12, the variation trend of the current density of the electro-red light device with the change of voltage was tested, and it was found that compound 12 had semiconductor properties, and its threshold voltage was 3.1V.

[0339] In Example 12, the brightness of the electro-red light device was tested as a function of voltage, and the maximum brightness of the device was found to be 6984 cd·m -2 .

[0340] In Example 12, the current efficiency of the electro-red light device was tested as the brightness changed, and it was found that the device had a brightness of 3.1 cd·m -2 When the current efficiency reaches the maximum value of 12.2cd·A -1 .

[0341] In Example 12, the power efficiency of the electro-red light device was tested as the brightness changed, and the device was found to have a power efficiency of 3.1 cd·m -2 When the power efficiency reaches the maximum value of 12.6lm·W -1 .

[0342] In Example 12, the external quantum efficiency of the electro-red light device was tested for the change in current density, and the device was found to have a brightness of 3.1 cd·m -2 When , the maximum external quantum efficiency of 27.5% is obtained.

[0343] In Example 12, the electroluminescence spectrum of the electroluminescent red light device is as follows: Fig.16 As shown, it can be seen from this figure that the electroluminescence peak of the device is at 660nm.

[0344] The present invention is described in detail above in conjunction with specific embodiments and / or exemplary examples and drawings, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A cyanoquinoxaline red photothermal excitation delayed fluorescent material, characterized in that: The cyanoquinoxaline red photothermal excitation delayed fluorescence material is compound 12:

2. A method for preparing the cyanoquinoxaline red photothermal excited delayed fluorescent material according to claim 1, characterized in that: The material is prepared from raw materials including halogenated aromatic ketone compounds and diaminophthalonitrile compounds, and the method comprises the following steps: Step 1, adding a halogenated aromatic ketone compound and reactant I to a solvent, stirring the reaction, and obtaining an intermediate I, wherein the halogenated aromatic ketone compound is 1,2-bis(4-bromophenyl)ethane-1,2-dione, the reactant I is a diaminophthalonitrile compound, which is 2,3-diaminoterephthalonitrile, and the intermediate I is 2,3-bis(4-bromophenyl)quinoxaline-5,8-dicarbonitrile; Step 2, adding intermediate I and reactant II into a solvent, wherein reactant II is diphenylphosphine chloride, and reflux reaction to obtain 2-(4-bromophenyl)-3-(4-(diphenylphosphoryl)phenyl)quinoxaline-5,8-dicarbonitrile; Step 3, adding 2-(4-bromophenyl)-3-(4-(diphenylphosphoryl)phenyl)quinoxaline-5,8-dicarbonitrile and aromatic amine compound III to a solvent, wherein the aromatic amine compound III is triphenylamine-4-boric acid pinacol ester, and reflux reaction to obtain a dicyanoquinoxaline compound, wherein the dicyanoquinoxaline compound is 2-(4'-(diphenylamino)-[1,1'-biphenyl]-4-yl)-3-(4-(diphenylphosphoryl)phenyl)quinoxaline-5,8-dicarbonitrile, i.e., compound 12.

3. A use of the cyanoquinoxaline red photothermal excitation delayed fluorescent material according to claim 1, characterized in that: Used to prepare electro-red light devices.

4. An electroluminescent red light device prepared from the cyanoquinoxaline red light thermally excited delayed fluorescent material according to claim 1, characterized in that: The guest material of the light-emitting layer of the electro-red light device comprises the cyanoquinoxaline-based red light thermally excited delayed fluorescent material according to claim 1 .

Images