CN106831875A - Thermal excitation delayed fluorescence material of main part based on phosphine heteroaryl derivative and its preparation method and application - Google Patents

Abstract

A thermally excited delayed fluorescent host material based on phosphine heteroaryl derivatives and its preparation method and application, which relate to a thermally excited delayed fluorescent host material and its preparation method and application. It aims to solve the technical problem that the existing planar heat-excited delayed fluorescent dye molecules are prone to quenching, resulting in low device efficiency. The structural formula of the thermally excited delayed fluorescent host material of the present invention is: Preparation method: Add o-dibromoaryl compound, phenylphosphine dichloride, and n-butyllithium into tetrahydrofuran, mix well, react under the protection of argon, then pour into water, extract with dichloromethane to obtain organic layer, after drying, directly purify or purify after sulfuration/and oxidation to obtain a thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives; wherein the o-dibromoaryl compound is o-dibromobenzene or 2,3-di bromonaphthalene. The fluorescent host material based on the phosphine heteroaryl derivative is used in thermal excitation delayed fluorescence electroluminescent devices.

Description

Thermally Excited Delayed Fluorescence Host Materials Based on Phosphine Heteroaryl Derivatives and Its Preparation Method law and application

technical field

The invention relates to a heat-excited delayed fluorescent host material and a preparation method and application thereof.

Background technique

Due to its low starting voltage and high luminous efficiency, organic light-emitting diodes have attracted extensive research. As the third-generation flat-panel display and lighting technology, organic light-emitting diodes generally use phosphorescent dyes to construct phosphorescent electroluminescence. , but because the construction of phosphorescent dyes is often accompanied by the presence of noble metals, this increases the cost of preparation and is not environmentally friendly. Therefore, there is an urgent need for other types of dyes to replace phosphorescent dyes. Recently, thermally excited delayed fluorescence technology, known as the third generation of organic electroluminescent technology, has made great research progress. Thermally excited delayed fluorescent dyes can jump from their own triplet state to singlet reverse gap. Transforming triplet excitons into singlet excitons and then using them to emit light can theoretically achieve 100% internal quantum efficiency. Devices prepared with such dyes also have high efficiency, comparable to phosphorescent devices. Meanwhile, thermally excited delayed fluorescent dyes are all pure organic compounds, with low preparation cost and environmental friendliness. In order to achieve high device efficiency, the host material of a thermally excited delayed fluorescence device needs to have the following three points: 1. It has a high triplet energy level, so that the energy can be transferred from the host to the guest; 2. Good current carrying 3. It has weak intermolecular force to prevent the emission quenching caused by the strong intermolecular interaction between host and guest molecules between host molecules. Usually, planar thermally excited delayed fluorescent dye molecules can effectively promote the carrier transport ability due to their strong intermolecular interactions. However, due to their strong intermolecular forces, they will also promote molecular aggregation, which will Quenching the emission reduces the device efficiency.

Contents of the invention

The present invention aims to solve the technical problem that existing planar thermally excited delayed fluorescent dye molecules are prone to quenching, resulting in low device efficiency, and provides a thermally excited delayed fluorescent host material based on phosphine heteroaryl derivatives and its preparation method and application.

The structural formula of the thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives of the present invention is:

Denoted as DPDPA;

or Denoted as DPDPSA;

or Where X=S or O, Y=S or O, when X=Y=S, it is recorded as DPDPS ₂ A; when X=S, Y=O, it is recorded as DPDPSOA; when X=Y=O, it is recorded as DPDPO ₂ A;

or Denoted as DPDPP;

or Denoted as DPDPSP;

or Where X=S or O, Y=S or O, when X=Y=S, it is recorded as DPDPS ₂ P; when X=S, Y=O, it is recorded as DPDPSOP; when X=Y=O, it is recorded as DPDPO ₂ p.

The preparation method of the above-mentioned thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives is as follows:

Add o-dibromoaryl compound, phenylphosphine dichloride, and n-butyllithium into tetrahydrofuran (THF) at a molar ratio of 1:(1~1.5):(2~4), under argon protection Under the condition of -60～-85℃, react for 1～3 hours, then pour into water, extract with dichloromethane to obtain the organic layer, dry the organic layer liquid, directly purify or vulcanize/and oxidize After further purification, a thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives is obtained; wherein the o-dibromoaryl compound is o-dibromobenzene or 2,3-dibromonaphthalene.

The application of the above-mentioned thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives is to use it in thermally excited delayed fluorescent electroluminescent devices.

A method for preparing a thermally excited delayed fluorescence (TADF) electroluminescent device using a thermally excited delayed fluorescence host material based on a phosphine heteroaryl derivative is implemented in the following steps:

1. Put the glass or plastic substrate cleaned with deionized water into a vacuum evaporation apparatus, the vacuum degree is 1×10 ^{- 6} mbar, the evaporation rate is set to 0.1nm s ^-1 , and evaporate The plating material is an anode conductive layer with indium tin oxide and a thickness of 100nm;

2. Evaporating a hole injection layer of MoO ₃ with a thickness of 5-30 nm on the anode conductive layer;

3. The evaporation material on the hole injection layer is NPB (N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine ), a hole transport layer with a thickness of 40-70 nm;

4. An electron blocking layer with a thickness of 5 to 20 nm is deposited on the hole transport layer as mCP (1,3-bis-9-carbazolylbenzene);

5. On the electron blocking layer, continue to vapor-deposit a host material (thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives) and a guest material DMAC-DPS/4CzTPNPh (bis[4-(9, 9-Dimethyl-9,10-dihydroacridine)phenyl]sulfone/2,3,5,6-tetrakis(3,6-diphenyl-9-carbazolyl)-terephthalonitrile , the doping concentration of the guest material is 5% to 15%);

6. The vapor deposition material on the light-emitting layer is DPEPO (bis[2-((oxo)diphenylphosphino)phenyl]ether), a hole blocking layer with a thickness of 5-20nm;

7. Evaporating an electron transport layer of Bphen (4,7-diphenyl-1,10-phenanthroline) with a thickness of 20 to 50 nm on the hole blocking layer;

8. An electron injection layer whose material is LiF (lithium fluoride) and whose thickness is 1 to 30 nm is evaporated on the electron transport layer;

9. Evaporating a cathode conductive layer made of metal Al and having a thickness of 100-200 nm on the electron injection layer, and packaging to obtain a thermally excited delayed fluorescence (TADF) electroluminescence device.

The present invention constructs a host material based on phosphine heteroaryl derivatives for thermally excited delayed fluorescence devices, and the material is a stable host material obtained by introducing phosphorus atoms on the aryl group and further vulcanization or/and oxidation. Select phosphine heteroaryl derivatives as the host material. First, as a material containing phosphine atom-heteroatom molecules, the host molecule has a higher triplet energy level, and this type of host has a planar structure, P=O or P= The S group has the function of polarizing molecules, which improves the electron injection and transport capabilities of the molecules, making this type of molecular materials have good carrier transport capabilities. (Oxidation and vulcanization) adjust the geometric configuration of molecules, thereby inhibiting the interaction between molecules and quenching, so that the host material can effectively inhibit the aggregation of molecules while having good carrier transport capabilities. Therefore, the efficiency of the thermally excited delayed fluorescence device is effectively improved. In summary, the use of phosphine heteroaryl derivative host materials in electroluminescent devices in the present invention includes the following advantages:

1. Maintain a high triplet energy level to ensure the effective transfer of energy from the subject to the object.

2. Improve the carrier injection and transport capabilities of electroluminescent device materials. The electroluminescent device prepared based on the host material of phosphine heteroaryl derivatives reduces the turn-on voltage to 2.5-2.8V, and has good thermodynamic stability. The pyrolysis temperature is 290°C-398°C, and at the same time, the luminous efficiency and brightness of the organic electroluminescent material are improved, and the invention is mainly applied to organic electroluminescent diode devices.

Description of drawings

Fig. 1 is the synthetic compound DPDPA ultraviolet fluorescence spectrogram of embodiment one, wherein represents the ultraviolet absorption spectrogram of DPDPA/dichloromethane with □ curve, represents the fluorescence emission spectrogram of DPDPA/dichloromethane with □ curve;

Fig. 2 is the thermogravimetric analysis spectrogram of the synthetic DPDPA of embodiment one;

Fig. 3 is the ultraviolet fluorescence spectrogram of the compound DPDPSA synthesized in embodiment two, wherein the ultraviolet absorption spectrogram of DPDPSA/dichloromethane is represented by the curve, and the fluorescence emission spectrogram of DPDPSA/dichloromethane is represented by the curve;

Fig. 4 is the thermogravimetric analysis spectrogram of the synthetic DPDPSA of embodiment two;

Fig. 5 is the compound DPDPS ₂ A ultraviolet fluorescence spectrograms that embodiment three synthesizes, and wherein represents the ultraviolet absorption spectrogram of DPDPS ₂ A/dichloromethane with □ curve, represents the fluorescence emission of DPDPS ₂ A/dichloromethane with □ curve Spectrum;

Fig. 6 is the thermogravimetric analysis spectrogram of the DPDPS ₂ A synthesized in embodiment three;

Fig. 7 is the ultraviolet fluorescence spectrogram of the compound DDPPSOA synthesized in Example 4, wherein the ultraviolet absorption spectrum of DDPPSOA/dichloromethane is represented by a curve, and the fluorescence emission spectrum of DDPPSOA/dichloromethane is represented by a curve;

Fig. 8 is the thermogravimetric analysis spectrogram of the synthetic DDPPSOA of embodiment four;

Fig. 9 is the compound DPDPO ₂ A ultraviolet fluorescence spectrograms that embodiment five synthesizes, and wherein represents the ultraviolet absorption spectrogram of DPDPO ₂ A/dichloromethane with □ curve, represents the fluorescence emission of DPDPO ₂ A/dichloromethane with □ curve Spectrum;

Fig. 10 is the thermogravimetric analysis spectrogram of DPDPO ₂ A synthesized in embodiment five;

Fig. 11 is the voltage-current density relationship curve of the thermally excited delayed fluorescent device of application example 1, wherein ■ represents DPDPA, ● represents DPDPSA, ▲ represents DPDPS ₂ A, ▼ represents DPDPSOA, and ◆ represents DPDPO ₂ A ;

Fig. 12 is the voltage-brightness relationship curve of the thermally excited delayed fluorescent device of Application Example 1, where ■ represents DPDPA, ● represents DPDPSA, ▲ represents DPDPS ₂ A, ▼ represents DPDPSOA, and ◆ represents DPDPO ₂ A;

Fig. 13 is the luminance-current efficiency relationship curve of the thermally excited delayed fluorescent device of application example 1, wherein ■ represents DPDPA, ● represents DPDPSA, ▲ represents DPDPS ₂ A, ▼ represents DPDPSOA, and ◆ represents DPDPO ₂ A ;

Fig. 14 is the luminance-power efficiency relationship curve of the thermally excited delayed fluorescent device of application example 1, wherein DPDPA is represented by ■, DPDPSA is represented by ●, DPDPS ₂ A is represented by ▲, DPDPSOA is represented by ▼, and DPDPO ₂ A is represented by ◆ ;

Fig. 15 is the luminance-external quantum efficiency relationship curve of the thermally excited delayed fluorescent device of the first application example, where DPDPA is represented by ■, DPDPSA by ●, DPDPS ₂ A by ▲, DPDPSOA by ▼, and DPDPO ₂ by ◆ A;

Fig. 16 is the electroluminescence spectrum of the thermally excited delayed fluorescence device of application example 1, wherein DPDPA is represented by ■, DPDPSA is represented by ●, DPDPS _{2 A is represented by ▲, DPDPSOA is represented by ▼, and DPDPO 2 A} is represented by ◆;

Fig. 17 is the ultraviolet fluorescence spectrogram of the compound DPDPP synthesized in Example 6, wherein the ultraviolet absorption spectrum of DPDPP/dichloromethane is represented by a curve, and the fluorescence emission spectrum of DPDPP/dichloromethane is represented by a curve;

Fig. 18 is the thermogravimetric analysis spectrogram of the DPDPP synthesized in embodiment six;

Fig. 19 is the ultraviolet fluorescence spectrogram of the compound DPDPSP synthesized in Example 7, wherein the ultraviolet absorption spectrum of DPDPSP/dichloromethane is represented by a curve, and the fluorescence emission spectrum of DPDPSP/dichloromethane is represented by a curve;

Fig. 20 is the thermogravimetric analysis spectrogram of the DPDPSP synthesized in embodiment seven;

Fig. 21 is the compound DPDPS ₂ P ultraviolet fluorescence spectrograms synthesized in embodiment eight, wherein the ultraviolet absorption spectrogram of DPDPS ₂ P/dichloromethane is represented by ■ curve, and the fluorescence emission of DPDPS ₂ P/dichloromethane is represented by □ curve Spectrum;

Figure 22 is the thermogravimetric analysis spectrum of DPDPS ₂ P synthesized in Example 8;

Fig. 23 is the ultraviolet fluorescence spectrogram of the compound DPDPSOP synthesized in Example 9, wherein the ultraviolet absorption spectrum of DPDPSOP/dichloromethane is represented by a curve, and the fluorescence emission spectrum of DPDPSOP/dichloromethane is represented by a curve;

Fig. 24 is the thermogravimetric analysis spectrogram of the DPDPSOP synthesized in embodiment nine;

Fig. 25 is the compound DPDPO ₂ P ultraviolet fluorescence spectrograms synthesized in embodiment ten, wherein the ultraviolet absorption spectrogram of DPDPO ₂ P/dichloromethane is represented by □ curve, and the fluorescence emission of DPDPO ₂ P/dichloromethane is represented by □ curve Spectrum;

Fig. 26 is the thermogravimetric analysis spectrogram of DPDPO ₂ P synthesized in embodiment ten;

Fig. 27 is the voltage-current density relationship curve of the thermally excited delayed fluorescent device of application example 2, where DPDPP is represented by □, DPDPSP is represented by ○, DPDPS ₂ P is represented by △, DPDPSOP is represented by ▽, and DPDPO ₂ P is represented by ◇ ;

Fig. 28 is the voltage-brightness relationship curve of the thermally excited delayed fluorescent device of Application Example 2, where DPDPP is represented by □, DPDPSP is represented by ○, DPDPS _{2 P is represented by △, DPDPSOP is represented by ▽, and DPDPO 2 P} is represented by ◇;

Fig. 29 is the luminance-current efficiency relationship curve of the thermally excited delayed fluorescent device of application example 2, wherein DPDPP is represented by □, DPDPSP is represented by ○, DPDPS ₂ P is represented by △, DPDPSOP is represented by ▽, and DPDPO ₂ P is represented by ◇ ;

Fig. 30 is the luminance-power efficiency relationship curve of the thermally excited delayed fluorescent device of Application Example 2, where DPDPP is represented by □, DPDPSP is represented by ○, DPDPS ₂ P is represented by △, DPDPSOP is represented by ▽, and DPDPO ₂ P is represented by ◇ ;

Figure 31 is the luminance-external quantum efficiency relationship curve of the thermally excited delayed fluorescent device of the second application example, where DPDPP is represented by □, DPDPSP is represented by ○, DPDPS ₂ P is represented by △, DPDPSOP is represented by ▽, and DPDPO ₂ is represented by ◇ P;

Fig. 32 is the electroluminescence spectrum of the thermally excited delayed fluorescence device of Application Example 2, where DPDPP is represented by □, DPDPSP by ○, DPDPS ₂ P by △, DPDPSOP by ▽, and DPDPO ₂ P by ◇.

detailed description

Embodiment 1: The structural formula of the thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives in this embodiment is denoted as DPDPA; or denoted as DPDPSA; or Where X=S or O, Y=S or O, when X=Y=S, it is recorded as DPDPS ₂ A; when X=S, Y=O, it is recorded as DPDPSOA; when X=Y=O, it is recorded as DPDPO ₂ A; or denoted as DPDPP; or denoted as DPDPSP; or Where X=S or O, Y=S or O, when X=Y=S, it is recorded as DPDPS ₂ P; when X=S, Y=O, it is recorded as DPDPSOP; when X=Y=O, it is recorded as DPDPO ₂ p.

Specific embodiment two: The preparation method of the thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives described in specific embodiment one is as follows:

Add o-dibromoaryl compound, phenylphosphine dichloride, and n-butyllithium into tetrahydrofuran (THF) at a molar ratio of 1:(1~1.5):(2~4), under argon protection Under the condition of -60～-85℃, react for 1～3 hours, then pour into water, extract with dichloromethane to obtain the organic layer, dry the organic layer liquid, directly purify or vulcanize/and oxidize After further purification, a thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives is obtained; wherein the o-dibromoaryl compound is o-dibromobenzene or 2,3-dibromonaphthalene.

Specific embodiment three: the difference between this embodiment and specific embodiment two is that the vulcanization process is: adding sulfur powder to the organic layer liquid, stirring and reacting at a temperature of 15-30°C for 0.5-2 hours, Complete vulcanization. Others are the same as in the second embodiment.

Embodiment 4: The difference between this embodiment and Embodiment 2 or 3 is that the oxidation process is as follows: add H ₂ O ₂ to the organic layer liquid, and stir at a temperature of -5 to 20°C React for 0.5 to 2 hours to complete the oxidation. Others are the same as the second or third specific embodiment.

Specific embodiment five: The synthesis method of the thermally excited delayed fluorescence host material DPDPA based on phosphine heteroaryl derivatives in this embodiment is as follows: o-dibromobenzene, phenylphosphine dichloride, and n-butyllithium in a molar ratio of 1:(1~1.5):(2~4) ratio is added to tetrahydrofuran (THF), reacted for 1~3 hours at a temperature of -60~-85°C, then poured into water, washed with dichloromethane Extract to obtain an organic layer, dry the organic layer liquid with anhydrous sodium sulfate, and use a mixed solvent of petroleum ether and dichloromethane as an eluent for column chromatography purification to obtain a thermal excitation retardation based on phosphine heteroaryl derivatives Fluorescent host material DPDPA; wherein the ratio of the amount of o-dibromobenzene to the volume of tetrahydrofuran is 1 mmol: (10-25) ml.

Specific embodiment six: The synthesis method of the thermally excited delayed fluorescence host material DPDPSA based on phosphine heteroaryl derivatives in this embodiment is as follows: o-dibromobenzene, phenylphosphine dichloride, and n-butyllithium in a molar ratio of 1:(1~1.5):(2~4) ratio is added to tetrahydrofuran (THF), reacted for 1~3 hours at a temperature of -60~-85°C, then poured into water, washed with dichloromethane Extract to obtain an organic layer, dry the organic layer liquid with anhydrous sodium sulfate, add sulfur powder, stir at a temperature of 15-30°C for sulfidation reaction for 0.5-2 hours, filter with suction, and remove dichloromethane by rotary evaporation Solvent, then use the mixed solvent of ethanol and dichloromethane as eluent to carry out column chromatography purification, obtain the thermally excited delayed fluorescence host material DPDPSA based on phosphine heteroaryl derivatives; wherein the amount of the substance of o-dibromobenzene and tetrahydrofuran The volume ratio of the sulfur powder is 1mmol:(10-25)ml;

Embodiment 7: The synthesis method of the thermally excited delayed fluorescence host material DPDPS ₂ A based on phosphine heteroaryl derivatives in this embodiment is as follows: mix o-dibromobenzene, phenylphosphine dichloride, and n-butyllithium in moles Add the ratio of 1:(1~1.5):(2~4) into tetrahydrofuran (THF), react at the temperature of -60~-85°C for 1~3 hours, then pour it into water, use two Extract with methyl chloride to obtain an organic layer, dry the organic layer liquid with anhydrous sodium sulfate, add sulfur powder, stir at a temperature of 15-30°C for sulfidation reaction for 1-2 hours, filter with suction, and remove disulfide by rotary evaporation. Chloromethane solvent, then carry out column chromatography purification with the mixed solvent of ethanol and dichloromethane as eluent, obtain the thermally excited delayed fluorescence host material DPDPSA based on phosphine heteroaryl derivative; Wherein the amount of the substance of o-dibromobenzene The volume ratio of tetrahydrofuran is 1 mmol: (10-25) ml; the ratio of the amount of sulfur powder added to the amount of phenylphosphine dichloride is (0.5-0.75): 1.

Embodiment 8: The synthesis method of the thermally excited delayed fluorescence host material DDPPSOA based on phosphine heteroaryl derivatives in this embodiment is as follows: o-dibromobenzene, phenylphosphine dichloride, and n-butyllithium in a molar ratio of 1:(1~1.5):(2~4) ratio is added to tetrahydrofuran (THF), reacted for 1~3 hours at a temperature of -60~-85°C, then poured into water, washed with dichloromethane Extract to obtain an organic layer, dry the organic layer liquid with anhydrous sodium sulfate, add sulfur powder, and stir at a temperature of 15-30°C for sulfidation reaction for 1-2 hours; then add H ₂ O ₂ , at temperature Stir at -5 to 20°C for oxidation reaction for 0.5 to 2 hours; wash with sodium bisulfite solution and water respectively, extract with dichloromethane, dry with anhydrous sodium sulfate, remove the dichloromethane solvent by rotary evaporation, and then Carry out column chromatography purification with the mixed solvent of ethanol and dichloromethane as eluent, obtain the thermally excited delayed fluorescence host material DDPPSOA based on phosphine heteroaryl derivative; The ratio is 1mmol: (10-25) ml; the ratio of the amount of the added sulfur powder to the amount of the phenylphosphine dichloride is (0.5-0.75): 2; the added H ₂ O ₂ and benzene The ratio (10-15) of the amount of substances of phosphine dichloride: 1.

Specific embodiment nine: The synthesis method of the thermally excited delayed fluorescence host material DPDPO ₂ A based on phosphine heteroaryl derivatives in this embodiment is as follows: o-dibromobenzene, phenylphosphine dichloride, and n-butyllithium are molarally Add the ratio of 1:(1~1.5):(2~4) into tetrahydrofuran (THF), react at the temperature of -60~-85°C for 1~3 hours, then pour it into water, use two Extract with methyl chloride, add H ₂ O ₂ to the organic layer, stir at -5-20°C for oxidation reaction for 0.5-2 hours; wash with sodium bisulfite solution and water, extract with dichloromethane, no After drying with sodium sulfate in water, the dichloromethane solvent was removed by rotary evaporation, and then the mixed solvent of ethanol and dichloromethane was used as the eluent for column chromatography purification to obtain the thermally excited delayed fluorescence host material DPDPO based on phosphine heteroaryl derivatives. ₂ A; wherein the ratio of the amount of substance of o _- dibromobenzene to the volume of THF is 1mmol: (10～25)ml; the ratio of the amount of substance of added H2O2 to phenylphosphine dichloride ( ₂₀ ～ 25): 1.

Specific Embodiment Ten: The synthesis method of the thermally excited delayed fluorescence host material DPDPP based on phosphine heteroaryl derivatives in this embodiment is as follows: massage 2,3-dibromonaphthalene, phenylphosphine dichloride, and n-butyllithium The molar ratio is 1:(1~1.5):(2~4) and added into tetrahydrofuran (THF), and reacted for 1~3 hours at a temperature of -60~-85°C, then poured into water, and used Extract with dichloromethane to obtain an organic layer, dry the organic layer liquid with anhydrous sodium sulfate, and perform column chromatography purification with a mixed solvent of petroleum ether and dichloromethane as eluent to obtain DPDPP; wherein 2,3-dichloromethane The ratio of the amount of bromonaphthalene to the volume of tetrahydrofuran is 1 mmol: (10-25) ml.

Embodiment 11: The synthesis method of the thermally excited delayed fluorescence host material DPDPSP based on phosphine heteroaryl derivatives in this embodiment is as follows: 2,3-dibromonaphthalene, phenylphosphine dichloride, n-butyllithium Add it into tetrahydrofuran (THF) at a molar ratio of 1:(1~1.5):(2~4), react at a temperature of -60~-85°C for 1~3 hours, and then pour it into water. Extract with dichloromethane to obtain an organic layer, dry the organic layer liquid with anhydrous sodium sulfate, add sulfur powder, stir at a temperature of 15-30°C for sulfidation reaction for 0.5-2 hours, suction filter, and rotary evaporate Remove the dichloromethane solvent, and then use the mixed solvent of ethanol and dichloromethane as the eluent to carry out column chromatography purification to obtain the thermally excited delayed fluorescence host material DPDPSP based on phosphine heteroaryl derivatives; wherein 2,3-dibromo The ratio of the amount of substance of naphthalene to the volume of THF is 1mmol: (10-25) ml; the ratio of the amount of substance of the added sulfur powder to the amount of substance of phenylphosphine dichloride is (0.5-0.75): 2.

Specific Embodiment Twelve: The synthesis method of the thermally excited delayed fluorescence host material DPDPS ₂ P based on phosphine heteroaryl derivatives in this embodiment is as follows: 2,3-dibromonaphthalene, phenylphosphine dichloride, n-butyl Lithium base is added to tetrahydrofuran (THF) at a molar ratio of 1:(1~1.5):(2~4), reacted for 1~3 hours at a temperature of -60~-85°C, and then poured into Extract in water with dichloromethane to obtain an organic layer, dry the organic layer liquid with anhydrous sodium sulfate, add sulfur powder, stir at a temperature of 15-30°C for sulfidation reaction for 1-2 hours, suction filter, The dichloromethane solvent was removed by rotary evaporation, and then the mixed solvent of ethanol and dichloromethane was used as the eluent for column chromatography purification to obtain the thermally excited delayed fluorescence host material DPDPS ₂ P based on phosphine heteroaryl derivatives; where 2, The ratio of the amount of substance of 3-dibromonaphthalene to the volume of tetrahydrofuran is 1mmol: (10～25) ml; the ratio of the amount of substance of the added sulfur powder to the amount of substance of phenylphosphine dichloride is (0.5 ~0.75):1.

Specific Embodiment Thirteen: The synthesis method of the thermally excited delayed fluorescence host material DPDPSOP based on phosphine heteroaryl derivatives in this embodiment is as follows: 2,3-dibromonaphthalene, phenylphosphine dichloride, n-butyllithium Add it into tetrahydrofuran (THF) at a molar ratio of 1:(1~1.5):(2~4), react at a temperature of -60~-85°C for 1~3 hours, and then pour it into water. Extract with dichloromethane to obtain an organic layer, dry the organic layer liquid with anhydrous sodium sulfate, add sulfur powder, stir at a temperature of 15-30°C for sulfidation reaction for 0.5-2 hours; then add H ₂ O _2. Stir and carry out the oxidation reaction at a temperature of -5 to 20°C for 0.5 to 2 hours; wash with sodium bisulfite solution and water respectively, extract with dichloromethane, dry with anhydrous sodium sulfate, and remove dichloride by rotary evaporation Methane solvent, and then use the mixed solvent of ethanol and dichloromethane as the eluent to carry out column chromatography purification to obtain the thermally excited delayed fluorescence host material DPDPSOP based on phosphine heteroaryl derivatives; the substance of 2,3-dibromonaphthalene The ratio of the amount of sulfur powder to the volume of tetrahydrofuran is 1 mmol: (10-25) ml; the ratio of the amount of sulfur powder added to the amount of phenylphosphine dichloride is (0.5-0.75): 2; The ratio of the amount of H ₂ O ₂ to the amount of phenylphosphine dichloride (10-15): 1.

Specific Embodiment Fourteen: The synthesis method of the thermally excited delayed fluorescence host material DPDPO ₂ P based on phosphine heteroaryl derivatives in this embodiment is as follows: 2,3-dibromonaphthalene, phenylphosphine dichloride, n-butyl Lithium base is added to tetrahydrofuran (THF) at a molar ratio of 1:(1~1.5):(2~4), reacted for 1~3 hours at a temperature of -60~-85°C, and then poured into In water, extract with dichloromethane to obtain an organic layer, add H ₂ O ₂ , and stir at a temperature of -5 to 20°C for oxidation reaction for 0.5 to 2 hours; remove the dichloromethane solvent by rotary evaporation, and then ethanol and The mixed solvent of dichloromethane is carried out column chromatography purification as eluent, obtains the thermally excited delayed fluorescence host material DPDPO ₂ P based on phosphine heteroaryl derivative; The volume ratio is 1 mmol: (10-25) ml; the ratio of the added H ₂ O ₂ to the amount of phenylphosphine dichloride (20-25): 1.

Embodiment 15: The application of the thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives in Embodiment 1 is to use it in a thermally excited delayed fluorescence electroluminescent device.

Embodiment 16: A method for preparing a thermally excited delayed fluorescence (TADF) electroluminescent device using a thermally excited delayed fluorescence host material based on a phosphine heteroaryl derivative is implemented in the following steps:

1. Put the glass or plastic substrate cleaned with deionized water into a vacuum evaporation apparatus, the vacuum degree is 1×10 ^{- 6} mbar, the evaporation rate is set to 0.1nm s ^-1 , and evaporate The plating material is an anode conductive layer with indium tin oxide and a thickness of 100nm;

2. Evaporating a hole injection layer of MoO ₃ with a thickness of 5-30 nm on the anode conductive layer;

3. The evaporation material on the hole injection layer is NPB (N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine ), a hole transport layer with a thickness of 40-70 nm;

4. An electron blocking layer with a thickness of 5 to 20 nm is deposited on the hole transport layer as mCP (1,3-bis-9-carbazolylbenzene);

5. On the electron blocking layer, continue to vapor-deposit a host material (thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives) and a guest material DMAC-DPS/4CzTPNPh (bis[4-(9, 9-Dimethyl-9,10-dihydroacridine)phenyl]sulfone/2,3,5,6-tetrakis(3,6-diphenyl-9-carbazolyl)-terephthalonitrile , the doping concentration of the guest material is 5% to 15%);

6. The vapor deposition material on the light-emitting layer is DPEPO (bis[2-((oxo)diphenylphosphino)phenyl]ether), a hole blocking layer with a thickness of 5-20nm;

7. Evaporating an electron transport layer of Bphen (4,7-diphenyl-1,10-phenanthroline) with a thickness of 20 to 50 nm on the hole blocking layer;

8. An electron injection layer whose material is LiF (lithium fluoride) and whose thickness is 1 to 30 nm is evaporated on the electron transport layer;

9. Evaporating a cathode conductive layer made of metal Al and having a thickness of 100-200 nm on the electron injection layer, and packaging to obtain a thermally excited delayed fluorescence (TADF) electroluminescence device.

Verify the beneficial effects of the present invention with the following examples:

Embodiment 1: The synthesis method of the thermally excited delayed fluorescence host material DPDPA based on phosphine heteroaryl derivatives in this embodiment is carried out according to the following steps:

1. Add 1mmol of o-dibromobenzene, 1mmol of phenylphosphine dichloride, and 2mmol of n-butyllithium into a 50ml three-necked round-bottom flask filled with 20ml of THF. Under the protection of argon, the temperature is -78 After stirring for ₂ hours under the condition of ℃, pour it into water, and then extract it with dichloromethane to obtain an organic layer. A mixed solvent with a volume ratio of 6:1 was used as an eluent for column chromatography purification to obtain DPDPA.

The DPDPA prepared by the present embodiment, the data measured by the mass spectrometer are: m/z: 368.09 (100.0%), 369.09 (26.2%), 370.10 (3.3%); GC-MS: m/z (%): 368 (100 ) [M ⁺ ]; Elemental Analysis of C ₂₄ H ₁₈ P ₂ : C, 78.26; H, 4.93. Thus it can be seen that the structural formula of DPDPA is:

The ultraviolet fluorescence spectrum of the thermally excited delayed fluorescence host material DPDPA based on phosphine heteroaryl derivatives obtained in this example is shown in FIG. 1 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescence host material DPDPA based on phosphine heteroaryl derivatives obtained in this example is shown in FIG. 2 . It can be seen from FIG. 2 that the cracking temperature of DPDPA reaches 290° C.

Embodiment 2: The synthesis method of the thermally excited delayed fluorescence host material DPDPSA based on phosphine heteroaryl derivatives in this embodiment is carried out according to the following steps:

1. Add 1mmol of o-dibromobenzene, 1.2mmol of phenylphosphine dichloride, and 2mmol of n-butyllithium into a 50ml three-necked round-bottomed flask equipped with 20ml of THF, under the protection of argon, at a temperature of After stirring for 2 hours at -78°C, pour it into water, then extract with dichloromethane to obtain an organic layer, dry the organic layer liquid with anhydrous sodium sulfate, add 0.3mmol sulfur powder to the organic layer liquid, Under stirring for 0.5 hours for sulfidation, suction filtration, rotary evaporation to remove the dichloromethane solvent, and then column chromatography purification with a mixed solvent of ethanol and dichloromethane volume ratio 1:20 as eluent, to obtain a derivative based on phosphine heteroaryl Thermal excitation delayed fluorescent host material DPDPSA.

The DPDPSA prepared in this embodiment, the data measured by the mass spectrometer are: m/z: 400.06 (100.0%), 401.06 (26.8%), 402.06 (4.7%), 402.07 (3.3%), 403.06 (1.2%); GC- MS: m/z (%): 400(100) [M ⁺ ]; Elemental Analysis of _{C24H18P2S :} C, 71.99; H, _4.53 ; S, 8.01. Thus it can be seen that the structural formula of DPDPSA is

The ultraviolet fluorescence spectrum of the thermally excited delayed fluorescence host material DPDPSA based on phosphine heteroaryl derivatives obtained in this embodiment is shown in FIG. 3 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescence host material DPDPSA based on phosphine heteroaryl derivatives obtained in this example is shown in FIG. 4 . It can be seen from FIG. 4 that the cracking temperature of DPDPSA reaches 324° C.

Example 3: The synthesis method of the thermally excited delayed fluorescence host material DPDPS ₂ A based on phosphine heteroaryl derivatives in this example is carried out according to the following steps:

1. Mix 1mmol of o-dibromobenzene, 1.2mmol of phenylphosphine dichloride, 2mmol of n-butyllithium and 20ml of THF in a 50ml three-neck round bottom flask, under argon protection, at a temperature of -78°C After stirring at low temperature for 3 hours, pour it into water, and then extract with dichloromethane to obtain an organic layer. After drying the organic layer liquid with anhydrous sodium sulfate, add 0.6 mmol of sulfur powder, and stir at a temperature of 20°C for sulfidation reaction After 1 hour, remove the methylene chloride solvent by suction filtration and rotary evaporation, and then purify by column chromatography using a mixed solvent of ethanol and methylene chloride with a volume ratio of 1:20 as the eluent to obtain a thermal excitation delay based on phosphine heteroaryl derivatives. Fluorescent host material DPDPS ₂ A.

The DPDPS ₂ A prepared in this example, the data measured by the mass spectrometer are: m/z: 432.03 (100.0%), 433.04 (26.2%), 434.03 (9.0%), 434.04 (3.7%), 435.03 (2.4%), 433.03 (1.6%); GC-MS: m/z (%): 432 (100) [M ⁺ ]; Elemental Analysis of C ₂₄ H ₁₈ P ₂ S ₂ : C, 66.65; H, 4.20; S, 14.83. Thus it can be seen that the structural formula of DPDPS ₂ A is

The ultraviolet fluorescence spectrum of the thermally excited delayed fluorescence host material DPDPS ₂ A based on phosphine heteroaryl derivatives obtained in this example is shown in FIG. 5 .

The thermogravimetric analysis spectrum of DPDPS ₂ A, a thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives obtained in this example, is shown in Fig. 6. From Fig. 6, it can be seen that the cracking temperature of DPDPS ₂ A reaches 332°C.

Example 4: In this example, the synthesis method of the thermally excited delayed fluorescence host material DDPPSOA based on phosphine heteroaryl derivatives is carried out according to the following steps:

Mix 1mmol of o-dibromobenzene, 1.2mmol of phenylphosphine dichloride, 2mmol of n-butyllithium and 20ml of THF in a 50ml three-neck round bottom flask, and stir at -78°C under argon protection After 1 to 3 hours, pour into water, extract with dichloromethane to obtain an organic layer, dry the organic layer liquid with anhydrous sodium sulfate, add 0.35 mmol of sulfur powder, and stir at a temperature of 20°C to carry out sulfidation reaction 1 Add 12mmol H ₂ O ₂ , and stir at 0°C for oxidation reaction for 1 hour; wash with sodium bisulfite solution and water, extract with dichloromethane, dry over anhydrous sodium sulfate, and remove by rotary evaporation Dichloromethane solvent, and a mixed solvent of ethanol and dichloromethane with a volume ratio of 1:20 is used as an eluent for column chromatography purification to obtain a thermally excited delayed fluorescence host material DDPPSOA based on phosphine heteroaryl derivatives;

The DDPPSOA prepared in this embodiment, the data measured by the mass spectrometer are: m/z: 416.06 (100.0%), 417.06 (26.2%), 418.05 (4.5%), 418.06 (3.7%), 419.05 (1.2%); GC- MS: m/z (%): 416 (100) [M ⁺ ]; Elemental Analysis of _{C24H18OP2S :} C, _69.22 ; H, 4.36; O, 3.84; S, 7.70. Thereby it can be seen that the structural formula of the DDPPSOA prepared in the present embodiment is:

The ultraviolet fluorescence spectrum of the thermally excited delayed fluorescence host material DDPPSOA based on phosphine heteroaryl derivatives obtained in this embodiment is shown in FIG. 7 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescence host material DDPPSOA based on phosphine heteroaryl derivatives obtained in this example is shown in FIG. 8 . It can be seen from FIG. 8 that the cracking temperature of DDPPSOA in this example reaches 341° C.

Embodiment 5: The synthesis method of the thermally excited delayed fluorescence host material DPDPO ₂ A based on phosphine heteroaryl derivatives in this embodiment is carried out according to the following steps:

1. Mix 1mmol of o-dibromobenzene, 1.2mmol of phenylphosphine dichloride, 2mmol of n-butyllithium and 20ml of THF in a 50ml three-neck round bottom flask, under argon protection, at a temperature of -78°C After stirring at low temperature for 3 hours, pour it into water, and then extract with dichloromethane to obtain an organic layer. After drying the organic layer liquid with anhydrous sodium sulfate, add 25 mmol of H ₂ O ₂ , and stir at a temperature of 0°C. Oxidation reaction for 1 hour; wash with sodium bisulfite solution and water respectively, extract with dichloromethane, dry over anhydrous sodium sulfate, remove the dichloromethane solvent by rotary evaporation, and use a mixed solvent of ethanol and dichloromethane with a volume ratio of 1:20 Purified by eluent column chromatography to obtain DPDPO ₂ A.

The DPDPO ₂ A prepared in this embodiment, the data measured by the mass spectrometer are: m/z: 400.08 (100.0%), 401.08 (26.2%), 402.08 (3.6%); GC-MS: m/z (%): 400 (100) [M ⁺ ]; Elemental Analysis of C ₂₄ H ₁₈ O ₂ P ₂ : C, 72.00; H, 4.53; O, 7.99. Thereby it can be seen that the structural formula of DPDPO ₂ A is:

The ultraviolet fluorescence spectrum of the thermally excited delayed fluorescence host material DPDPO ₂ A based on phosphine heteroaryl derivatives obtained in this example is shown in FIG. 9 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescence host material DPDPO ₂ A based on phosphine heteroaryl derivatives obtained in this example is shown in Fig. 10 , and it can be seen from Fig. 10 that the cracking temperature of DPDPO ₂ A reaches 372°C.

Application Example 1: The thermally excited delayed fluorescence host materials DPDPA, DPDPSA, DPDPS ₂ A, DDPPSOA, and DPDPO ₂ A prepared in Examples 1 to 5 based on phosphine heteroaryl derivatives were used to prepare electroluminescent devices, specifically according to Follow these steps:

1. Put the glass or plastic substrate cleaned with deionized water into a vacuum evaporation apparatus, the vacuum degree is 1×10 ^{- 6} mbar, the evaporation rate is set to 0.1nm s ^-1 , and evaporate The plating material is indium tin oxide, and the anode conductive layer with a thickness of 100nm;

2. MoO ₃ is evaporated on the anode conductive layer, and a hole injection layer with a thickness of 20nm is formed;

3. On the hole injection layer, the evaporation material is NPB, and a hole transport layer with a thickness of 50 nm;

4. An electron blocking layer with a thickness of 10nm is mCP evaporated on the hole transport layer;

5. The host material (the thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives) and the guest material DMAC-DPS (the doping concentration of the guest material is 14%) are continuously vapor-deposited on the electron blocking layer with a thickness of 30 nm. luminous layer;

6. On the light-emitting layer, the evaporation material is DPEPO, and a hole blocking layer with a thickness of 15nm;

7. On the hole blocking layer, the vapor deposition material is Bphen, and an electron transport layer with a thickness of 40nm;

8. An electron injection layer whose thickness is 20nm is LiF deposited on the electron transport layer;

9. Evaporating metal Al on the electron injection layer with a cathode conductive layer with a thickness of 150 nm, and packaging to obtain a thermally excited delayed fluorescence (TADF) electroluminescent device.

The voltage-current density relationship curve of the electroluminescent device prepared in this application example is shown in FIG. 11 . Among them, ■ means DPDPA, ● means DPDPSA, ▲ means DPDPS ₂ A, ▼ means DPDPSOA, ◆ means DPDPO ₂ A. It can be seen from Figure 11 that with the increase of voltage, the current density of the device shows an increasing trend.

The voltage-brightness relationship curve of the electroluminescent device in this application example is shown in Figure 12, where ■ represents DPDPA, ● represents DPDPSA, ▲ represents DPDPS ₂ A, ▼ represents DPDPSOA, and ◆ represents DPDPO ₂ A. It can be seen from this figure that the turn-on voltage of the electroluminescent device prepared with DPDPA is 2.6V, the turn-on voltage of the electroluminescent device prepared with DPDPSA is 2.8V, and the turn-on voltage of the electroluminescent device prepared with DPDPS ₂ A The start-up voltage of the electroluminescent device prepared with DPDPSOA is 2.7V, and the start-up voltage of the electroluminescent device prepared with DPDPO ₂ A is 2.8V.

The luminance-current efficiency relationship curve of the electroluminescent device in this application example is shown in Figure 13, where ■ indicates DPDPA, ● indicates DPDPSA, ▲ indicates DPDPS ₂ A, ▼ indicates DPDPSOA, and ◆ indicates DPDPO ₂ A. It can be seen from the figure that the maximum current efficiency of the electroluminescent device prepared with DPDPA is 33.2cd·A ^-1 , and the maximum current efficiency of the electroluminescent device prepared with DPDPSA is 33.8cd ·A ^-1 , the maximum current efficiency of the electroluminescent device prepared with DPDPS ₂ A is 17.0cd·A ^-1 , and the maximum current efficiency of the electroluminescent device prepared with DPDPSOA is 21.1cd·A ^-1 , the maximum current efficiency of the electroluminescent device prepared with DPDPO ₂ A was 33.0cd·A ^-1 .

The luminance-power efficiency relationship curve of the electroluminescent device of this application example is shown in Figure 14, wherein ■ represents DPDPA, ● represents DPDPSA, ▲ represents DPDPS ₂ A, ▼ represents DPDPSOA, ◆ represents DPDPO ₂ A, from this figure It can be seen that the maximum power efficiency of the electroluminescent device prepared by DPDPA is 38.6lm·W ^-1 , the maximum power efficiency of the electroluminescent device prepared by DPDPSA is 39.4lm·W ^-1 , and the maximum power efficiency of the electroluminescent device prepared by DPDPS ₂ A The maximum power efficiency of the electroluminescent device is 19.1lm·W ^-1 , the maximum power efficiency of the electroluminescent device prepared by DPDPSOA is 24.5lm·W ^-1 , the electroluminescent device prepared by DPDPO ₂ A The maximum power efficiency of the device is 38.4lm·W ^-1 .

The luminance-external quantum efficiency relationship curve of the electroluminescent device of this application example is shown in Figure 15, wherein ■ represents DPDPA, ● represents DPDPSA, ▲ represents DPDPS ₂ A, ▼ represents DPDPSOA, ◆ represents DPDPO ₂ A, thus The figure shows that the maximum external quantum efficiency of the electroluminescent device prepared with DPDPA is 17.5%, the maximum external quantum efficiency of the electroluminescent device prepared with DPDPSA is 17.8%, and the maximum external quantum efficiency of the electroluminescent device prepared with DPDPS ₂ A is 8.9 %, the maximum external quantum efficiency of the electroluminescent device prepared with DPDPSOA is 11.1%, and the maximum external quantum efficiency of the electroluminescent device prepared with DPDPO ₂ A is 17.4%.

The electroluminescence spectrum diagram of the electroluminescent device of this application example is shown in Figure 16, where ■ indicates DPDPA, ● indicates DPDPSA, ▲ indicates DPDPS ₂ A, ▼ indicates DPDPSOA, and ◆ indicates DPDPO ₂ A, and it can be seen from this figure The electroluminescent peaks of the electroluminescent devices prepared with DPDPA are all at 480nm.

Embodiment 6: The synthesis method of the thermally excited delayed fluorescence host material DPDPP based on phosphine heteroaryl derivatives in this embodiment is realized according to the following steps:

Mix 1mmol of 2,3-dibromonaphthalene, 1-2mmol of phenylphosphine dichloride, 2-3mmol of n-butyllithium and 10-25ml of THF, and stir at -78°C under the protection of argon for 1-3 Pour it into water after 1 hour, and then extract with dichloromethane to obtain an organic layer. After drying over anhydrous NaSO ₄ , distill the solvent off under reduced pressure, and use a mixed solvent of petroleum ether and dichloromethane with a volume ratio of 6:1 as the eluent Purified by column chromatography to obtain DPDPP.

The DPDPP prepared in this embodiment, the data measured by the mass spectrometer are: m/z: 468.12 (100.0%), 469.12 (34.6%), 470.13 (5.9%); GC-MS: m/z (%): 468 (100 ) [M ⁺ ]; Elemental Analysis of C ₃₂ H ₂₂ P ₂ : C, 82.04; H, 4.73. Thus it can be seen that the structural formula of DPDPP is:

The ultraviolet fluorescence spectrum of the thermally excited delayed fluorescence host material DPDPP based on phosphine heteroaryl derivatives obtained in this example is shown in FIG. 17 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescence host material DPDPP based on phosphine heteroaryl derivatives obtained in this example is shown in FIG. 18 . It can be seen from the figure that the cracking temperature of DPDPP in this example reaches 309° C.

Embodiment 7: The synthesis method of the thermally excited delayed fluorescence host material DPDPSP based on phosphine heteroaryl derivatives in this embodiment is carried out according to the following steps:

1mmol of 2,3-dibromonaphthalene, 1.2mmol of phenylphosphine dichloride, and 2mmol of n-butyllithium were added to a 50ml three-necked round-bottomed flask containing 25ml of tetrahydrofuran (THF), and under the protection of argon, the React for 3 hours at a temperature of -78°C, then pour into water, extract with dichloromethane to obtain an organic layer, dry the organic layer liquid with anhydrous sodium sulfate, add 0.35mmol sulfur powder, and heat at a temperature of 20°C Stirring under the condition of sulfuration reaction for 1 hour, suction filtration, rotary evaporation to remove dichloromethane solvent, and then column chromatography purification with the mixed solvent of ethanol and dichloromethane volume ratio 1:20 as eluent, obtain the phosphine-based Thermally Excited Delayed Fluorescence Host Material DPDPSP of Heteroaryl Derivatives.

The DPDPSP prepared in this embodiment, the data measured by the mass spectrometer are: m/z: 500.09 (100.0%), 501.10 (34.9%), 502.10 (5.9%), 502.09 (4.8%), 503.09 (1.6%); GC- MS: m/z (%): 500(100) [M ⁺ ]; Elemental Analysis of _{C32H22P2S :} C, 76.79; H, _4.43 ; S, 6.41. Thus it can be seen that the structural formula of DPDPSP is

The ultraviolet fluorescence spectrum of the thermally excited delayed fluorescence host material DPDPSP based on phosphine heteroaryl derivatives obtained in this example is shown in FIG. 19 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescence host material DPDPSP based on phosphine heteroaryl derivatives obtained in this example is shown in FIG. 20 . It can be seen from the figure that the cracking temperature of DPDPSP reaches 359° C.

Embodiment 8: The synthesis method of the thermally excited delayed fluorescence host material DPDPS ₂ P based on phosphine heteroaryl derivatives in this embodiment is realized according to the following steps:

1mmol of 2,3-dibromonaphthalene, 1.2mmol of phenylphosphine dichloride, and 2mmol of n-butyllithium were added to a 50ml three-necked round-bottomed flask containing 25ml of tetrahydrofuran (THF), and under argon protection, the React for 2 hours at a temperature of -78°C, then pour into water, extract with dichloromethane to obtain an organic layer, dry the organic layer liquid with anhydrous sodium sulfate, add 0.7mmol sulfur powder, and heat at a temperature of 22°C Stirring under the conditions of sulfuration reaction for 1.2 hours, suction filtration, rotary evaporation to remove the dichloromethane solvent, and then use the mixed solvent of ethanol and dichloromethane with a volume ratio of 1:20 as eluent, carry out column chromatography purification, and obtain the compound based on Thermally Excited Delayed Fluorescence Host Material DPDPS ₂ P of Phosphine Heteroaryl Derivatives;

The DPDPS ₂ P prepared in this example, the data measured by the mass spectrometer are: m/z: 532.06 (100.0%), 533.07 (34.9%), 534.06 (9.0%), 534.07 (6.4%), 535.06 (3.2%), 533.06 (1.6%); GC-MS: m/z (%): 532 (100) [M ⁺ ]; Elemental Analysis of C ₃₂ H ₂₂ P ₂ S ₂ : C, 72.16; H, 4.16; S, 12.04. Thus it can be seen that the structural formula of DPDPS ₂ P is

The ultraviolet fluorescence spectrum of DPDPS ₂ P obtained in this example is shown in FIG. 21 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescence host material DPDPS ₂ P based on phosphine heteroaryl derivatives obtained in this example is shown in Figure 22. It can be seen from the figure that the cracking temperature of DPDPS ₂ P in this example reaches 365°C .

Embodiment 9: In this embodiment, the synthesis method of DPDPSOP, the main material of the thermally excited delayed fluorescence device based on phosphine heteroaryl derivatives, is realized according to the following steps:

1mmol of 2,3-dibromonaphthalene, 1.2mmol of phenylphosphine dichloride, and 2mmol of n-butyllithium were added to a 50ml three-necked round-bottomed flask containing 25ml of tetrahydrofuran (THF), and under argon protection, the React for 2 hours at a temperature of -78°C, then pour into water, extract with dichloromethane to obtain an organic layer, dry the organic layer liquid with anhydrous sodium sulfate, add 0.35mmol of sulfur powder, and heat at a temperature of 22°C Stir under the condition of sulfidation reaction for 1.2 hours; then add 15mmol H ₂ O ₂ , stir at the temperature of 0°C for oxidation reaction for 1 hour; wash with sodium bisulfite solution and water respectively, extract with dichloromethane, no After drying over sodium sulfate water, the dichloromethane solvent was removed by rotary evaporation, and then a mixed solvent with a volume ratio of ethanol and dichloromethane of 1:20 was used as an eluent, and column chromatography purification was carried out to obtain phosphine heteroaryl derivatives based on Thermally excited delayed fluorescent host material DPDPSOP;

The DPDPSOP prepared in this embodiment, the data measured by the mass spectrometer are: m/z: 516.09 (100.0%), 517.09 (35.7%), 518.09 (6.3%), 518.08 (4.5%), 519.09 (1.7%); GC- MS: m/z (%): 516 (100) [M ⁺ ]; Elemental Analysis of _{C32H22OP2S :} C, _74.41 ; H, 4.29; O, 3.10; S, 6.21. Thereby it can be seen that the structural formula of DPDPSOP is:

The ultraviolet fluorescence spectrum of the thermally excited delayed fluorescence host material DPDPSOP based on phosphine heteroaryl derivatives obtained in this example is shown in FIG. 23 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescence host material DPDPSOP based on phosphine heteroaryl derivatives obtained in this example is shown in FIG. 24 . It can be seen from the figure that the cracking temperature of DPDPSOP in this example reaches 373°C.

Embodiment 10: The thermally excited delayed fluorescence host material DPDPO ₂ P based on phosphine heteroaryl derivatives in this embodiment is realized according to the following steps:

1mmol of 2,3-dibromonaphthalene, 1.2mmol of phenylphosphine dichloride, and 2mmol of n-butyllithium were added to a 50ml three-necked round-bottomed flask containing 25ml of tetrahydrofuran (THF), and under argon protection, the The reaction was carried out at -78°C for 2 hours, then poured into water, extracted with dichloromethane to obtain an organic layer, added with 30 mmol H ₂ O ₂ , and stirred at 0°C for an oxidation reaction for 1 hour; Wash with sodium bisulfite solution and water respectively, extract with dichloromethane, dry over anhydrous sodium sulfate, remove the dichloromethane solvent by rotary evaporation, and then use a mixed solvent of ethanol and dichloromethane with a volume ratio of 1:20 as eluent , and purified by column chromatography to obtain a thermally excited delayed fluorescence host material DPDPO ₂ P based on phosphine heteroaryl derivatives;

The DPDPO ₂ P prepared in this embodiment, the data measured by the mass spectrometer are: m/z: 500.11 (100.0%), 501.11 (34.7%), 502.12 (5.9%); GC-MS: m/z (%): 500 (100) [M ⁺ ]; Elemental Analysis of C ₃₂ H ₂₂ O ₂ P ₂ : C, 76.80; H, 4.43; O, 6.39. Thus it can be seen that the structural formula of DPDPO ₂ P is

The ultraviolet fluorescence spectrum of the thermally excited delayed fluorescence host material DPDPO ₂ P based on phosphine heteroaryl derivatives obtained in this example is shown in FIG. 25 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescence host material DPDPO ₂ P based on phosphine heteroaryl derivatives obtained in this example is shown in Figure 26, from which it can be seen that the cracking temperature of DPDPO ₂ P in this example reaches 398°C.

Application Example 2: The thermally excited delayed fluorescence host materials DPDPP, DPDPSP, DPDPS ₂ P, DPDPSOP, and DPDPO ₂ P prepared in Examples 6 to 10 based on phosphine heteroaryl derivatives were used to prepare electroluminescent devices, specifically Follow these steps:

1. Put the glass or plastic substrate cleaned with deionized water into a vacuum evaporation apparatus, the vacuum degree is 1×10 ^{- 6} mbar, the evaporation rate is set to 0.1nm s ^-1 , and evaporate The plating material is indium tin oxide, and the anode conductive layer with a thickness of 100nm;

2. MoO ₃ is evaporated on the anode conductive layer, and a hole injection layer with a thickness of 20nm is formed;

3. On the hole injection layer, the evaporation material is NPB, and a hole transport layer with a thickness of 50 nm;

4. An electron blocking layer with a thickness of 10nm is mCP evaporated on the hole transport layer;

5. On the electron blocking layer, continue to vapor-deposit a light-emitting layer with a thickness of 30nm of a host material (a thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives) and a guest material 4CzTPNPh (the doping concentration of the guest material is 14%) ;

6. On the light-emitting layer, the evaporation material is DPEPO, and a hole blocking layer with a thickness of 15nm;

7. On the hole blocking layer, the vapor deposition material is Bphen, and an electron transport layer with a thickness of 40nm;

8. An electron injection layer whose thickness is 20nm is LiF deposited on the electron transport layer;

9. Evaporating metal Al on the electron injection layer with a cathode conductive layer with a thickness of 150 nm, and packaging to obtain a thermally excited delayed fluorescence (TADF) electroluminescent device.

The voltage-current density relationship curve of the electroluminescent device prepared in this application example is shown in FIG. 27 . Among them, DPDPP is represented by □, DPDPSP by ○, DPDPS ₂ P by △, DPDPSOP by ▽, and DPDPO ₂ P by ◇. It can be seen from Figure 27 that with the increase of the voltage, the current density of the device shows an increasing trend.

The voltage-brightness relationship curve of the electroluminescent device in this application example is shown in Figure 28, where DPDPP is represented by □, DPDPSP by ○, DPDPS ₂ P by △, DPDPSOP by ▽, and DPDPO by ◇ ₂ p. It can be seen from this figure that the turn-on voltage of the electroluminescent device prepared with DPDPP is 2.7V, the turn-on voltage of the electroluminescent device prepared with DPDPSP is 4.5V, and the turn-on voltage of the electroluminescent device prepared with DPDPS ₂ P The start-up voltage of the electroluminescent device prepared with DPDPSOP is 2.8V, and the start-up voltage of the electroluminescent device prepared with DPDPO ₂ P is 2.8V.

The luminance-current efficiency relationship curve of the electroluminescent device of this application example is shown in Figure 29, wherein □ represents DPDPP, ○ represents DPDPSP, △ represents DPDPS ₂ P, ▽ represents DPDPSOP, and ◇ represents DPDPO ₂ p. It can be seen from the figure that the maximum current efficiency of the electroluminescent device prepared with DPDPP is 34.3cd·A ^-1 , and the maximum current efficiency of the electroluminescent device prepared with DPDPSP is 1.7cd·A ^-1 , the maximum current efficiency of the electroluminescent device prepared by DPDPS ₂ P is 17.0cd·A ^-1 , the maximum current efficiency of the electroluminescent device prepared by DPDPSOP is 26.5cd·A ^-1 , and the maximum current efficiency of the electroluminescent device by DPDPO ₂ The current efficiency of the electroluminescent device made of P reaches a maximum value of 23.0cd·A ^-1 .

The luminance-power efficiency relationship curve of the electroluminescent device of this application example is shown in Figure 30, wherein DPDPP is represented by □, DPDPSP is represented by ○, DPDPS ₂ P is represented by △, DPDPSOP is represented by ▽, and DPDPO ₂ is represented by ◇ p. It can be seen from the figure that the maximum power efficiency of the electroluminescent device prepared by DPDPP is 39.91lm·W ^-1 , and the maximum power efficiency of the electroluminescent device prepared by DPDPSP is 3.91lm·W ^-1 . The maximum power efficiency of the electroluminescent device prepared by ₂ P is 18.4lm·W ^{-1 , the maximum power efficiency of the electroluminescent device prepared by DPDPSOP is 30.81lm·W -1 ,} the maximum power efficiency of the electroluminescent device prepared by DPDPO ₂ P The maximum power efficiency of the electroluminescent device is 19.5lm·W ^-1 .

The luminance-external quantum efficiency relationship curve of the electroluminescent device in this application example is shown in Figure 31, where □ represents DPDPP, ○ represents DPDPSP, △ represents DPDPS ₂ P, ▽ represents DPDPSOP, and ◇ represents DPDPO ₂ p. It can be seen from this figure that the maximum external quantum efficiency of the electroluminescent device prepared with DPDPP is 18.1%, the maximum external quantum efficiency of the electroluminescent device prepared with DPDPSP is 1.9%, and the maximum external quantum efficiency of the electroluminescent device prepared with DPDPS ₂ P The efficiency is 9.0%, the maximum external quantum efficiency of the electroluminescent device prepared with DPDPSOP is 14%, and the maximum external quantum efficiency of the electroluminescent device prepared with DPDPO ₂ P is 12.1%.

The electroluminescent spectrum of the electroluminescent device in this application example is shown in Figure 32, where DPDPP is represented by □, DPDPSP is represented by ○, DPDPS ₂ P is represented by △, DPDPSOP is represented by ▽, and DPDPO ₂ P is represented by ◇ , it can be seen from this figure that the electroluminescence peak of the electroluminescence device prepared with DPDPP is at 610nm, the electroluminescence peak of the electroluminescence device prepared with DPDPSP is at 613nm, and the electroluminescence peak of the electroluminescence device prepared with DPDPS ₂ P The electroluminescence peak is at 613nm, the electroluminescence peak of the electroluminescence device prepared by DPDPSOP is at 615nm, and the electroluminescence peak of the electroluminescence device prepared by DPDPO ₂ P is at 618nm.

Claims (7)

1. A thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives, characterized in that the structural formula of the material is Denoted as DPDPA; or for Denoted as DPDPSA; or for Where X=S or O, Y=S or O, when X=Y=S, it is recorded as DPDPS ₂ A; when X=S, Y=O, it is recorded as DPDPSOA; when X=Y=O, it is recorded as DPDPO ₂ A; or for Denoted as DPDPP; or for Denoted as DPDPSP; or for Where X=S or O, Y=S or O, when X=Y=S, it is recorded as DPDPS ₂ P; when X=S, Y=O, it is recorded as DPDPSOP; when X=Y=O, it is recorded as DPDPO ₂ p. 2. the method for preparing the thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives according to claim 1, is characterized in that the method is as follows: Add o-dibromoaryl compound, phenylphosphine dichloride, and n-butyllithium into tetrahydrofuran in a molar ratio of 1:(1~1.5):(2~4), under the protection of argon, in React at a temperature of -60 to -85°C for 1 to 3 hours, then pour into water, extract with dichloromethane to obtain an organic layer, dry the liquid in the organic layer, and then directly purify or sulfide/oxidize and then purify. A thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives is obtained; wherein the o-dibromoaryl compound is o-dibromobenzene or 2,3-dibromonaphthalene. 3. The preparation method of the thermally excited delayed fluorescent host material based on phosphine heteroaryl derivatives according to claim 2, characterized in that the vulcanization process is: adding sulfur powder to the organic layer liquid, at a temperature of 15 Stir and react at ~30°C for 0.5-2 hours to complete vulcanization. 4. The preparation method of the thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives according to claim 2, characterized in that the oxidation process is: adding H ₂ O ₂ to the organic layer liquid, The reaction is carried out with stirring at a temperature of -5 to 20° C. for 0.5 to 2 hours to complete the oxidation. 5. The preparation method of the thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives according to claim 2, 3 or 4, characterized in that: The synthetic method of the thermally excited delayed fluorescence host material DPDPA based on phosphine heteroaryl derivatives is as follows: the molar ratio of o-dibromobenzene, phenylphosphine dichloride, and n-butyllithium is 1: (1～1.5): ( 2~4) was added into tetrahydrofuran, reacted at -60~-85°C for 1~3 hours, then poured into water, extracted with dichloromethane to obtain an organic layer, and the organic layer liquid was used without After drying with sodium sulfate water, the mixed solvent of petroleum ether and dichloromethane is used as eluent for column chromatography purification to obtain the thermally excited delayed fluorescence host material DPDPA based on phosphine heteroaryl derivatives; wherein the substance of o-dibromobenzene The ratio of the amount to the volume of tetrahydrofuran is 1mmol: (10～25)ml; The synthetic method of the thermally excited delayed fluorescence host material DPDPSA based on phosphine heteroaryl derivatives is as follows: the molar ratio of o-dibromobenzene, phenylphosphine dichloride, and n-butyllithium is 1: (1～1.5): ( 2~4) was added into tetrahydrofuran, reacted at -60~-85°C for 1~3 hours, then poured into water, extracted with dichloromethane to obtain an organic layer, and the organic layer liquid was used without After drying with sodium sulfate water, add sulfur powder, stir at 15-30°C for sulfidation reaction for 0.5-2 hours, remove the dichloromethane solvent by suction filtration and rotary evaporation, and then use the mixed solvent of ethanol and dichloromethane Carry out column chromatography purification as the eluent, and obtain the thermally excited delayed fluorescence host material DPDPSA based on phosphine heteroaryl derivatives; wherein the ratio of the amount of o-dibromobenzene to the volume of tetrahydrofuran is 1 mmol: (10-25) ml; the ratio of the amount of substance of the added sulfur powder to the amount of substance of phenylphosphine dichloride is (0.5～0.75): 2; The synthesis method of the thermally excited delayed fluorescence host material DPDPS ₂ A based on phosphine heteroaryl derivatives is as follows: the molar ratio of o-dibromobenzene, phenylphosphine dichloride, and n-butyllithium is 1: (1～1.5) : The ratio of (2~4) is added into tetrahydrofuran, and reacted for 1~3 hours at a temperature of -60~-85°C, then poured into water, extracted with dichloromethane to obtain an organic layer, and the organic layer liquid After drying with anhydrous sodium sulfate, add sulfur powder, stir at a temperature of 15-30°C for sulfidation reaction for 1-2 hours, remove the dichloromethane solvent by suction filtration and rotary evaporation, and then dichloromethane solvent with ethanol and dichloromethane The mixed solvent is the eluting agent and is purified by column chromatography to obtain the thermally excited delayed fluorescence host material DPDPSA based on phosphine heteroaryl derivatives; wherein the ratio of the amount of o-dibromobenzene to the volume of tetrahydrofuran is 1 mmol: (10～ 25) ml; the ratio of the amount of substance of the added sulfur powder to the amount of substance of phenylphosphine dichloride is (0.5～0.75): 1; The synthesis method of the thermally excited delayed fluorescence host material DDPPSOA based on phosphine heteroaryl derivatives is as follows: the molar ratio of o-dibromobenzene, phenylphosphine dichloride, and n-butyllithium is 1: (1～1.5): ( 2~4) was added into tetrahydrofuran, reacted at -60~-85°C for 1~3 hours, then poured into water, extracted with dichloromethane to obtain an organic layer, and the organic layer liquid was used without After sodium sulfate water is dried, add sulfur powder, stir at a temperature of 15-30°C for sulfidation reaction for 1-2 hours; then add H ₂ O ₂ , stir at a temperature of -5-20°C for oxidation React for 0.5 to 2 hours; wash with sodium bisulfite solution and water respectively, extract with dichloromethane, dry over anhydrous sodium sulfate, remove the dichloromethane solvent by rotary evaporation, and rinse with a mixed solvent of ethanol and dichloromethane Reagent was purified by column chromatography to obtain a thermally excited delayed fluorescence host material DDPPSOA based on phosphine heteroaryl derivatives; wherein the ratio of the amount of o-dibromobenzene to the volume of tetrahydrofuran was 1 mmol: (10-25) ml; The ratio of the amount of substance of sulfur powder to the amount of substance of phenylphosphine dichloride is (0.5～0.75): 2; the ratio of added H ₂ O ₂ to the amount of substance of phenylphosphine dichloride ( 10～15): 1; The synthesis method of the thermally excited delayed fluorescence host material DPDPO ₂ A based on phosphine heteroaryl derivatives is as follows: the molar ratio of o-dibromobenzene, phenylphosphine dichloride, and n-butyllithium is 1: (1～1.5) : The ratio of (2~4) is added into tetrahydrofuran, and reacted for 1~3 hours at a temperature of -60~-85°C, then poured into water, extracted with dichloromethane to obtain an organic layer, and the organic layer liquid After drying with anhydrous sodium sulfate, add H ₂ O ₂ , and stir at -5 to 20°C for oxidation reaction for 0.5 to 2 hours; wash with sodium bisulfite solution and water, extract with dichloromethane, After drying with anhydrous sodium sulfate, the dichloromethane solvent was removed by rotary evaporation, and then the mixed solvent of ethanol and dichloromethane was used as the eluent for column chromatography purification to obtain a thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives DPDPO ₂ A; wherein the ratio of the amount of substance of o-dibromobenzene to the volume of tetrahydrofuran is 1mmol: (10～25) ml; the ratio of added H ₂ O ₂ to the amount of substance of phenylphosphine dichloride (20 ~25): 1; The synthesis method of the thermally excited delayed fluorescence host material DPDPP based on phosphine heteroaryl derivatives is as follows: the molar ratio of 2,3-dibromonaphthalene, phenylphosphine dichloride, and n-butyllithium is 1:(1～1.5 ): (2~4) ratio was added into tetrahydrofuran, reacted for 1~3 hours at a temperature of -60~-85°C, then poured into water, extracted with dichloromethane to obtain an organic layer, and the organic layer After the liquid is dried with anhydrous sodium sulfate, the mixed solvent of petroleum ether and dichloromethane is used as eluent for column chromatography purification to obtain DPDPP; the ratio of the amount of 2,3-dibromonaphthalene to the volume of tetrahydrofuran 1 mmol: (10-25) ml; The synthesis method of the thermally excited delayed fluorescence host material DPDPSP based on phosphine heteroaryl derivatives is as follows: 2,3-dibromonaphthalene, phenylphosphine dichloride, and n-butyllithium in a molar ratio of 1:(1～1.5 ): (2~4) ratio was added into tetrahydrofuran, reacted for 1~3 hours at a temperature of -60~-85°C, then poured into water, extracted with dichloromethane to obtain an organic layer, and the organic layer After the liquid is dried with anhydrous sodium sulfate, sulfur powder is added, and the vulcanization reaction is carried out with stirring at a temperature of 15-30°C for 0.5-2 hours. The dichloromethane solvent is removed by suction filtration and rotary evaporation. The mixed solvent is the eluent for column chromatography purification to obtain the thermally excited delayed fluorescence host material DPDPSP based on phosphine heteroaryl derivatives; wherein the ratio of the amount of 2,3-dibromonaphthalene to the volume of tetrahydrofuran is 1mmol : (10～25) ml; The ratio of the amount of substance of the added sulfur powder to the amount of substance of phenylphosphine dichloride is (0.5～0.75): 2; The synthesis method of the thermally excited delayed fluorescence host material DPDPS ₂ P based on phosphine heteroaryl derivatives is as follows: 2,3-dibromonaphthalene, phenylphosphine dichloride, and n-butyllithium in a molar ratio of 1:(1 ～1.5): (2～4) was added into tetrahydrofuran, reacted for 1～3 hours at a temperature of -60～-85°C, then poured into water, extracted with dichloromethane to obtain an organic layer, and After drying the organic layer liquid with anhydrous sodium sulfate, add sulfur powder, stir at a temperature of 15-30°C for sulfidation reaction for 1-2 hours, filter with suction, and remove the dichloromethane solvent by rotary evaporation, then add ethanol and dichloromethane The mixed solvent of methyl chloride is used as an eluent for column chromatography purification to obtain a thermally excited delayed fluorescence host material DPDPS ₂ P based on phosphine heteroaryl derivatives; wherein the amount of 2,3-dibromonaphthalene and the volume of tetrahydrofuran The ratio is 1mmol: (10 ~ 25) ml; the ratio of the amount of substance of the added sulfur powder to the amount of substance of phenylphosphine dichloride is (0.5 ~ 0.75): 1; The synthesis method of the thermally excited delayed fluorescence host material DPDPSOP based on phosphine heteroaryl derivatives is as follows: 2,3-dibromonaphthalene, phenylphosphine dichloride, and n-butyllithium in a molar ratio of 1:(1～1.5 ): (2 to 4) was added into tetrahydrofuran, reacted for 1 to 3 hours at a temperature of -60 to -85°C, then poured into water, extracted with dichloromethane to obtain an organic layer, and the organic layer After drying the liquid with anhydrous sodium sulfate, add sulfur powder, and stir at a temperature of 15-30°C for sulfidation reaction for 0.5-2 hours; then add H ₂ O ₂ , Stir for oxidation reaction for 0.5 to 2 hours; wash with sodium bisulfite solution and water respectively, extract with dichloromethane, dry with anhydrous sodium sulfate, remove the dichloromethane solvent by rotary evaporation, and then use a mixed solvent of ethanol and dichloromethane Carry out column chromatography purification for eluting agent, obtain the thermal excitation delayed fluorescence host material DPDPSOP based on phosphine heteroaryl derivative; Wherein the ratio of the amount of substance of 2,3-dibromonaphthalene to the volume of tetrahydrofuran is 1mmol: (10 ～25) ml; the ratio of the amount of substance of the added sulfur powder to the amount of phenylphosphine _dichloride is (0.5～0.75): ₂ ; The ratio of the amount of substance (10~15): 1; The synthesis method of the thermally excited delayed fluorescence host material DPDPO ₂ P based on phosphine heteroaryl derivatives is as follows: the molar ratio of 2,3-dibromonaphthalene, phenylphosphine dichloride, and n-butyllithium is 1:(1 ~1.5): (2~4) ratio was added to tetrahydrofuran, reacted for 1~3 hours at a temperature of -60~-85°C, then poured into water, extracted with dichloromethane to obtain an organic layer, added H ₂ O ₂ , stirred at -5-20°C for oxidation reaction for 0.5-2 hours; washed with sodium bisulfite solution and water, extracted with dichloromethane, dried over anhydrous sodium sulfate, and then evaporated Remove the dichloromethane solvent, and then use the mixed solvent of ethanol and dichloromethane as the eluent to perform column chromatography purification to obtain the thermally excited delayed fluorescence host material DPDPO ₂ P based on phosphine heteroaryl derivatives; where 2,3- The ratio of the amount of dibromonaphthalene to the volume of tetrahydrofuran is 1 mmol: (10-25) ml; the ratio of the amount of added H ₂ O ₂ to the amount of phenylphosphine dichloride (20-25): 1. 6. The application of the thermally excited delayed fluorescence host material based on phosphine heteroaryl derivatives according to claim 1, characterized in that the application is to use the thermally excited delayed fluorescent host material based on phosphine heteroaryl derivatives for thermal excitation Delayed fluorescence electroluminescent devices. 7. The application of the thermally excited delayed fluorescent host material based on phosphine heteroaryl derivatives according to claim 6, characterized in that the thermally excited delayed fluorescent host material is prepared based on the thermally excited delayed fluorescent host material based on phosphine heteroaryl derivatives The method for luminescent device is carried out in the following steps: 1. Put the glass or plastic substrate cleaned with deionized water into a vacuum evaporation apparatus, the vacuum degree is 1×10 ^-6 mbar, the evaporation rate is set to 0.1nm s ^-1 , and evaporate The plating material is an anode conductive layer with indium tin oxide and a thickness of 100nm; 2. Evaporating a hole injection layer of MoO ₃ with a thickness of 5-30 nm on the anode conductive layer; 3. The evaporation material on the hole injection layer is N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine, thickness A hole transport layer of 40-70nm nm; 4. Evaporating an electron blocking layer of 1,3-di-9-carbazolylbenzene with a thickness of 5 to 20 nm on the hole transport layer; 5. On the electron blocking layer, continue to vapor-deposit the thermally excited delayed fluorescence host material and guest material bis[4-(9,9-dimethyl-9,10- Dihydroacridine) phenyl] sulfur sulfone or 2,3,5,6-tetrakis (3,6-diphenyl-9-carbazolyl)-terephthalonitrile light-emitting layer, wherein the doping of the guest material The concentration is 5% to 15%; 6. The vapor deposition material on the light-emitting layer is DPEPO (bis[2-((oxo)diphenylphosphino)phenyl]ether), a hole blocking layer with a thickness of 5-20nm; 7. Evaporating an electron transport layer whose material is 4,7-diphenyl-1,10-phenanthroline and whose thickness is 20-50 nm on the hole blocking layer; 8. An electron injection layer with a thickness of 1 to 30 nm is deposited on the electron transport layer by evaporating lithium fluoride LiF; 9. Evaporating a cathode conductive layer made of metal Al and having a thickness of 100-200 nm on the electron injection layer, and packaging to obtain a thermally excited delayed fluorescence (TADF) electroluminescence device.