CN109054810A - Using diphenylsulfide as the thermal excitation delayed fluorescence material of main part of parent and its preparation and application - Google Patents

Abstract

The present invention provides a kind of using diphenylsulfide as the thermal excitation delayed fluorescence material of main part of parent and its preparation and application, the thermal excitation delayed fluorescence material of main part is modified diphenylsulfide with the diphenylphosphine oxygroup of different number and is obtained using diphenylsulfide as parent；Material of main part of the invention can effectively inhibit molecule and intermolecular interaction, to inhibit quenching effect.Material of the present invention is used to prepare thermal excitation delayed fluorescence electroluminescent device as luminescent layer and exciton barrier-layer.

Description

Thermally Excited Delayed Fluorescence Host Material Based on Diphenyl Sulfide and Its Preparation and Application application

technical field

The invention relates to an organic electroluminescent material, in particular to a thermally excited delayed fluorescent host material with diphenyl sulfide as a matrix and its preparation and application.

Background technique

Organic Light Emitting Diode (OLED) emerged as a new display technology and has attracted extensive attention of researchers. Electrofluorescence and electrophosphorescence are referred to as first and second generation OLEDs. Currently, thermally excited delayed fluorescence has received more attention and is called the third-generation OLED.

Since the report of organic light-emitting diode (OLED), due to its many advantages, it has been widely concerned and studied deeply. Organic light-emitting diodes are called the third-generation flat-panel display and lighting technology, and have outstanding advantages in energy saving and environmental protection.

In order to effectively utilize the singlet and triplet excitons generated in the process of electroluminescence, the current common method is to use phosphorescent dyes to construct electrophosphorescence, but the heavy metals involved in phosphorescent dyes are not only expensive but also pollute the environment, so it is urgent Other materials need to be used instead.

Recently, the thermally excited delayed fluorescence technology known as the third-generation organic electroluminescence technology has made good progress, in which the thermally excited delayed fluorescent dye can make the triplet state Excitons are transformed into singlet excitons, which are then used to emit light, thereby theoretically achieving 100% internal quantum efficiency.

Most of the current thermally excited delayed fluorescent dyes are pure organic compounds. The research on host materials of thermally excited delayed fluorescent dyes is still very limited. Therefore, it is necessary to purposely develop host materials suitable for them according to the characteristics of thermally excited delayed fluorescent dyes. Due to the high polarity of thermally excited delayed fluorescent dyes, they are easy to be quenched, and the interaction between molecules is strong. Therefore, it is necessary to develop a class that has outstanding carrier injection/transport properties and can effectively suppress intermolecular quenching. The high-efficiency host material of the effect is used in blue light-emitting luminescent devices, in order to improve the luminous efficiency and brightness of the devices. Since blue-light thermally excited delayed fluorescent materials often have obvious photoelectric oxidation decomposition effects, devices often use electron-transport-based host materials, which greatly limits the selection of materials and the improvement of device performance. A feasible solution to this problem is to design a host material that has a certain hole transport ability but does not affect the obvious electron-donating properties, so as to improve the balance of charge transport and ensure the stability of the device.

Contents of the invention

In order to achieve the above goals, the inventors have carried out intensive research and found that: thermally excited delayed fluorescence host materials based on diphenyl sulfide and their preparation and application, the p orbital of the sulfur atom in the diphenyl sulfide group Provides a strong electron donating ability, while the introduction of the phosphine group still maintains the overall electron transport properties of the host. The thermal excitation delayed fluorescence host material is obtained by modifying the benzene ring on the diphenyl sulfide with different numbers of aromatic phosphine groups. The thermal excitation delayed fluorescence host material provided by the present invention has low polarity and is not easy to be quenched. The efficiency of the device can be improved in the electroluminescence device, the current efficiency of the device reaches a maximum value of 32cd·A ^-1 , and the power efficiency reaches a maximum value of 22lm·W ^-1 , thus completing the present invention.

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

In a first aspect, the present invention provides a thermally excited delayed fluorescence host material, wherein the host material uses diphenyl sulfide as a host.

Wherein, the parent is modified by different numbers of aromatic phosphine groups, preferably each benzene ring is modified by 1 to 4 aromatic phosphine groups, more preferably each benzene ring is modified by 1 to 2 aromatic phosphine groups .

Wherein, the parent has the following structural formula after being modified by an aromatic phosphine group:

Wherein, X, Y, Z, and D are H or Ph ₂ PO, respectively.

In the second aspect, according to the preparation method of the thermally excited delayed fluorescence host material described in the first aspect of the present invention, the preparation method comprises the following steps:

Step 1-1, mix the halogenated raw material with diphenyl sulfide as the parent, diphenylphosphine, sodium acetate, catalyst and solvent I, react under the set conditions for 10-36h, add ice water to quench, solvent II is extracted to obtain an intermediate;

In step 1-2, the intermediate is oxidized with hydrogen peroxide and post-treated to obtain the product.

Described preparation method comprises the following steps:

Step 2-1, reacting diphenyl sulfide with lithium reagent for 10-24 hours, then adding halogenated diphenylphosphine, reacting for 10-24 hours, quenching with ice water, and extracting to obtain intermediate I';

In step 2-2, the intermediate I' is oxidized with hydrogen peroxide and post-treated to obtain the product.

In the third aspect, the use of the thermally excited delayed fluorescent host material in the first aspect above or the thermally excited delayed fluorescent host material prepared according to the preparation method in the second aspect is used in an electroluminescent device.

Description of drawings

Fig. 1 shows the ultraviolet fluorescence spectrogram of the thermally excited delayed fluorescence host material of embodiment 1, and the fluorescence spectrogram and the phosphorescence spectrogram dissolved in the dichloromethane solvent;

Fig. 2 shows the thermogravimetric analysis diagram of the thermally excited delayed fluorescence host material of Example 1;

Fig. 3 shows the ultraviolet fluorescence spectrogram of the thermal excitation delayed fluorescence host material of embodiment 2;

Fig. 4 shows the thermogravimetric analysis diagram of the thermally excited delayed fluorescence host material of Example 2;

Fig. 5 shows the ultraviolet fluorescence spectrogram of the thermally excited delayed fluorescence host material of embodiment 3, and the fluorescence spectrogram and the phosphorescence spectrogram dissolved in the dichloromethane solvent;

Fig. 6 shows the thermogravimetric analysis diagram of the thermally excited delayed fluorescence host material of Example 3;

Fig. 7 shows the ultraviolet fluorescence spectrogram of the thermally excited delayed fluorescence host material of Example 4, as well as the fluorescence spectrogram and phosphorescence spectrogram dissolved in dichloromethane solvent;

Figure 8 shows the thermogravimetric analysis diagram of the thermally excited delayed fluorescence host material of Example 4;

Fig. 9 shows the ultraviolet fluorescence spectrogram of the thermally excited delayed fluorescence host material of Example 5, as well as the fluorescence spectrogram and phosphorescence spectrogram dissolved in dichloromethane solvent;

Figure 10 shows the thermogravimetric analysis diagram of the thermally excited delayed fluorescence host material of Example 5;

Figure 11 shows the ultraviolet fluorescence spectrum spectrum of the thermally excited delayed fluorescence host material of Example 6, as well as the fluorescence spectrum and phosphorescence spectrum dissolved in dichloromethane solvent;

Figure 12 shows the thermogravimetric analysis diagram of the thermally excited delayed fluorescence host material of Example 6;

Fig. 13 shows the ultraviolet fluorescence spectrogram of the thermally excited delayed fluorescence host material of Example 7, as well as the fluorescence spectrogram and phosphorescence spectrogram dissolved in dichloromethane solvent;

Figure 14 shows the thermogravimetric analysis diagram of the thermally excited delayed fluorescence host material of Example 7;

Among them, Fig. 1, Fig. 3, Fig. 5, Fig. 7, Fig. 9, Fig. 11, and Fig. 13, ■ represents the ultraviolet spectrum of the thermally excited delayed fluorescent host material in dichloromethane solvent, and □ represents the thermally excited delayed fluorescent host The fluorescence spectrum graph of the material dissolved in dichloromethane solvent, ● represents the phosphorescence spectrum graph of the thermally excited delayed fluorescence host material dissolved in dichloromethane solvent;

Fig. 15, Fig. 16, Fig. 17, Fig. 18, Fig. 19, Fig. 20 respectively show the voltage-current density relation curve, the voltage-brightness relation curve, the luminance -Current efficiency relationship curve, luminance-power efficiency relationship curve, luminance-external quantum efficiency relationship curve, electroluminescence spectrum diagram;

Fig. 21, Fig. 22, Fig. 23, Fig. 24, Fig. 25, and Fig. 26 respectively show the voltage-current density relation curve, the voltage-brightness relation curve, the luminance -Current efficiency relationship curve, luminance-power efficiency relationship curve, luminance-external quantum efficiency relationship curve, electroluminescence spectrum diagram;

Fig. 27, Fig. 28, Fig. 29, Fig. 30, Fig. 31, Fig. 32 respectively show the voltage-current density relation curve, the voltage-brightness relation curve, the luminance -Current efficiency relationship curve, luminance-power efficiency relationship curve, luminance-external quantum efficiency relationship curve, electroluminescence spectrum diagram;

Fig. 33, Fig. 34, Fig. 35, Fig. 36, Fig. 37, Fig. 38 show respectively the voltage-current density relation curve, the voltage-brightness relation curve, the luminance -Current efficiency relationship curve, luminance-power efficiency relationship curve, luminance-external quantum efficiency relationship curve, electroluminescence spectrum diagram;

Fig. 39, Fig. 40, Fig. 41, Fig. 42, Fig. 43, Fig. 44 respectively show the voltage-current density relation curve, the voltage-brightness relation curve, the luminance -Current efficiency relationship curve, luminance-power efficiency relationship curve, luminance-external quantum efficiency relationship curve, electroluminescence spectrum diagram;

Fig. 45, Fig. 46, Fig. 47, Fig. 48, Fig. 49, Fig. 50 respectively show the voltage-current density relation curve, voltage-brightness relation curve, brightness -Current efficiency relationship curve, luminance-power efficiency relationship curve, luminance-external quantum efficiency relationship curve, electroluminescence spectrum diagram;

Fig. 51, Fig. 52, Fig. 53, Fig. 54, Fig. 55, and Fig. 56 respectively show the voltage-current density relation curve, voltage-brightness relation curve, brightness -Current efficiency relationship curve, luminance-power efficiency relationship curve, luminance-external quantum efficiency relationship curve, electroluminescence spectrum diagram.

Detailed ways

The following describes the present invention in detail, and the features and advantages of the present invention will become more clear and definite along with these descriptions.

The present invention is described in detail below.

According to the first aspect of the present invention, there is provided a thermally excited delayed fluorescence host material, the host material is based on diphenyl sulfide;

Wherein, the parent is modified by different numbers of aromatic phosphine groups, preferably each benzene ring is modified by 1 to 4 aromatic phosphine groups, more preferably each benzene ring is modified by 1 to 2 aromatic phosphine groups .

The parent has the following structural formula after being modified by an aromatic phosphine group:

Wherein, X, Y, Z, and D are H or Ph ₂ PO, respectively.

When X, Y, and Z are H, and D is Ph ₂ PO, the compound is recorded as DPSSPO, and its structural formula is (I);

When X, Y, D are H, and Z is Ph ₂ PO, the compound is recorded as 4DPSSPO, and its structural formula is (II);

When D and X are H, and Z and Y are Ph ₂ PO, the compound is recorded as 4,4'DPSDPO, and its structural formula is (III);

When Z and Y are H, and D and X are Ph ₂ PO, the compound is recorded as DPSDPO, and its structural formula is (IV);

When X is H, and D, Y and Z are Ph ₂ PO, the compound is recorded as 2,4,4'DPSTPO, and its structural formula is (V);

When Z is H, and D, X, Y are Ph ₂ PO, the compound is recorded as 2,2',4DPSTPO, and its structural formula is (VI);

When X, Y, Z, and D are all Ph ₂ PO, the compound is recorded as 2,2',4,4'DPSQPO, and its structural formula is (VII); the structural formula of each compound is as follows:

The aromatic phosphine oxide host material is constructed by changing the number of phosphine groups and the substitution position connection strategy. While reducing the singlet excited state energy level, it does not affect the triplet state energy level of the molecule at all. The group wraps the intermediate chromophore, inhibits the interaction between the chromophore and the object, and between the chromophore and the chromophore, thereby weakening the interaction between the subject and the object, and between the subject and the subject. At the same time, the phosphine oxide group itself does not affect the triplet state energy level, thereby obtaining a high triplet excited state energy, promoting the positive energy transfer between the host and the guest, and improving the device efficiency.

According to the second aspect of the present invention, there is provided a method for preparing the above-mentioned thermally excited delayed fluorescence host material, the preparation method comprising the following steps:

Step 1-1, mix the halogenated raw material with diphenyl sulfide as the parent, diphenylphosphine, sodium acetate, catalyst and solvent I, react under the set conditions for 10-36h, add ice water to quench, solvent II extraction to obtain the intermediate; the reaction temperature is 130°C. Extraction solvent II used dichloromethane.

In step 1-2, the intermediate is oxidized with hydrogen peroxide, and post-treated to obtain the product;

in,

In step 1-1, the catalyst is palladium acetate; the solvent I and solvent II are respectively DMF (N-N dimethylformamide), dichloromethane;

In step 1-1, the halogenated raw material based on diphenyl sulfide includes chloride, bromide, iodide, preferably bromide, more preferably selected from one or more of the following 4-bromodiphenylsulfide Ether, 4,4'-diphenylsulfide, 2-diphenylphosphinyloxy-4,4'-dibromo-diphenylsulfide, 2,2'-diphenylphosphinyloxy-4-bromo -Diphenylsulfide, 2,2'-diphenylphosphinyloxy-4,4'-dibromo-diphenylsulfide.

Among them, the molar ratio of diphenylphosphine to the bromide raw material based on diphenyl sulfide is (1～2): 1, and the molar ratio of palladium acetate to brominated diphenylphosphine oxysulfide It is (0.001～0.002):1, and the molar ratio of sodium acetate (sodium acetate) to brominated diphenylphosphinyl sulfide is (1～2):1.

In step 1-2, the post-treatment includes quenching, extraction, drying and concentrating the extract, and then subjecting the obtained concentrate to column chromatography, the eluent used is ethanol and ethyl acetate in a volume ratio of 1:20 . The extraction solvent is dichloromethane.

The products obtained by adopting this preparation method include 4DPSSPO, whose structural formula is (II); 4,4'DPSDPO, whose structural formula is (III); compound 2,4,4'DPSTPO, whose structural formula is (V); compound 2 ,2',4DPSTPO, its structural formula is (VI); compound 2,2',4,4'DPSQPO, its structural formula is (VII).

The preparation methods of the thermally excited delayed fluorescent host materials with different structures in the present invention are different. In addition to the above-mentioned preparation methods, the thermally excited delayed fluorescent host materials with different structures also adopt the following preparation methods.

The preparation method of the thermally excited delayed fluorescent host material according to the first aspect comprises the following steps:

Step 2-1, reacting diphenyl sulfide with lithium reagent for 10-24 hours, then adding halogenated diphenylphosphine, reacting for 10-24 hours, quenching with ice water, and extracting to obtain intermediate I';

In step 2-2, the intermediate I' is oxidized with hydrogen peroxide and post-treated to obtain the product.

in,

In step 2-1, the lithium reagent is n-butyl lithium, and the molar ratio of the lithium reagent to diphenyl sulfide is (3-0.5):1;

The halogenated diphenylphosphine is chlorodiphenylphosphine, bromodiphenylphosphine or iododiphenylphosphine, preferably chlorodiphenylphosphine;

In step 2-1, before adding the lithium reagent, tetramethylethylenediamine is also added;

More preferably, the molar ratio of lithium reagent to diphenyl sulfide is 1:1 or 2:1, the molar ratio of tetramethylethylenediamine to diphenyl sulfide is 1:1, and the ratio of halogenated diphenylphosphine to diphenyl sulfide is 1:1. The molar ratio of phenylene sulfide is 1:1.

In step 2-2, the post-treatment includes adding water to quench, extract, concentrate the extract, and then purify the concentrate by column chromatography. The eluent used was ethanol and ethyl acetate in a volume ratio of 1:20.

According to the third aspect of the present invention, the use of the thermally excited delayed fluorescent host material according to the first aspect or the thermally excited delayed fluorescent host material prepared according to the preparation method described in the second aspect, the thermally excited delayed fluorescent host material The material is used as a host material in a thermally excited delayed fluorescence electroluminescent device. Preferably, the preparation method for applying the thermally excited delayed fluorescent host material to a thermally excited delayed fluorescent electroluminescent device is realized in the following steps:

1. Put the plastic substrate cleaned with deionized water into the vacuum evaporation apparatus, the vacuum degree is 1×10 ^-6 mbar, the evaporation rate is set to 0.1nm s ^-1 , and the material is evaporated on the glass or plastic substrate Be indium tin oxide (ITO), the anode conductive layer that thickness is 10nm;

2. Evaporate hole injection layer material MoOx on the anode conductive layer to obtain a hole injection layer with a thickness of 10nm;

3. Evaporating the hole transport layer material NPB on the hole injection layer to obtain a hole transport layer with a thickness of 40nm;

4. On the hole transport layer, evaporate the blocking layer material mCP to obtain an exciton blocking layer with a thickness of 15nm;

5. Evaporating the luminescent layer material on the exciton blocking layer, the mixture of thermally excited delayed fluorescence host material and DMAC-DPS with diphenyl sulfide as the matrix, the thickness of the luminescent layer is 50nm;

6. On the light-emitting layer, continue to vapor-deposit a thermally excited delayed fluorescence host material hole blocking layer with diphenyl sulfide as the matrix, and the thickness of the hole blocking layer is 40nm;

7. Evaporating electron transport layer material Bphen on the hole blocking layer, with a thickness of 80nm electron transport layer;

8. Evaporate LiF, an electron injection layer material, on the electron transport layer, with a thickness of 10nm electron injection layer;

9. Evaporating and depositing a metal cathode conductive layer with a thickness of 10 nm on the electron injection layer to obtain an electroluminescence device.

In step 9, the metal is calcium, magnesium, silver, aluminum, calcium alloy, magnesium alloy, silver alloy or aluminum alloy, preferably aluminum.

The thermally excited delayed fluorescent electroluminescent device is a thermally excited delayed fluorescent electroluminescent device emitting blue light, preferably with a maximum current efficiency of 32cd·A ^-1 and a maximum power efficiency of 22lm·W ^-1 .

According to the thermally excited delayed fluorescent host material with diphenyl sulfide as the matrix and its preparation method and application provided by the present invention, it has the following beneficial effects:

(1) The thermally excited delayed fluorescent host material provided by the present invention can maintain a relatively high triplet energy level, ensuring the effective transfer of energy from the host to the guest;

(2) The thermal excitation delayed fluorescence host material provided by the present invention can effectively inhibit the interaction between molecules, thereby inhibiting the quenching effect;

(3) When the thermally excited delayed fluorescent host material provided by the present invention is applied to an electroluminescent device, it can improve the carrier injection and transport capabilities of the electroluminescent device material;

(4) The thermally excited delayed fluorescent host material provided by the present invention can be used not only as the host material of the light-emitting layer of the light-emitting device, but also as the material of the exciton blocking layer of the light-emitting device;

(5) The present invention can realize ultra-low voltage driven high-efficiency thermally excited delayed fluorescent blue light device, its current efficiency reaches a maximum value of 32cd·A ^-1 , and its power efficiency reaches a maximum value of 22lm·W ^-1 , which improves the performance of organic electroluminescent materials Luminous efficiency and brightness.

Example

The embodiments include: the preparation of the thermally excited delayed fluorescent host material involved in the present invention and the structural characterization of the product; and the application of the prepared thermally excited delayed fluorescent host material to electroluminescent devices; and the performance test of the electroluminescent devices.

Example 1

Mix 1mmol of diphenyl sulfide, 1mmol of tetramethylethylenediamine, 1mmol of n-butyllithium, and 10ml of dry diethyl ether, react at room temperature (25-30°C) for 16 hours, and add 1mmol of Ph ₂ PCl to the reaction system , after reacting for 16 hours, introducing the reacted product into ice water to quench the reaction, extracting with dichloromethane as a solvent, and drying the organic layer;

After the organic layer was dried, 1ml _H2O2 was added to oxidize it, and after extraction and _drying , the volume ratio of ethanol and ethyl acetate was 1:20 as the eluent and purified by column chromatography to obtain 2-diphenylphosphine Phenylsulfide (DPSSPO).

Wherein, the molar ratio of n-butyl lithium to diphenyl sulfide is 1:1, the ratio of tetramethylethylenediamine to diphenyl sulfide is 1:1, Ph ₂ PCl and diphenyl sulfide are The molar ratio of phenylene sulfide is 1:1.

Present embodiment 1 obtains 2-diphenylphosphinoxy diphenyl sulfide DPSSPO, and structural formula I is

The multifunctional modified DPSSPO prepared in this test was detected by nuclear magnetic resonance instrument, and the detection results were as follows:

1H-NMR (TMS, CDCl3, 400MHz): δ=7.775–7.724(m,4H),7.553-7.513(m,2H),7.480-7.436(m,4H),7.414-7.329(m,2H),7.221 -7.166 (m, 5H), 7.138-7.114 ppm (m, 2H); LDI-TOF: m/z (%): 386 (100) [M+].

In Example 1, the ultraviolet fluorescence spectrum of the thermally excited delayed fluorescence host material DPSSPO is obtained, and the phosphorescence spectrum is shown in FIG. 1 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescent host material DPSSPO obtained in Example 1 is shown in FIG. 2 . It can be seen from the figure that the cracking temperature of the thermally excited delayed fluorescent host material DPSSPO is 317°C.

The thermally excited delayed fluorescent host material obtained in Example 1 is used as a light-emitting layer (and a hole blocking layer) for the preparation of an electroluminescent device as follows:

1. Put the plastic substrate cleaned with deionized water into the vacuum evaporation apparatus, the vacuum degree is 1×10- ⁶ mbar, the evaporation rate is set to 0.1nm s- ¹ , and the material is evaporated on the glass or plastic substrate Be indium tin oxide (ITO), the anode conductive layer that thickness is 10nm;

2. Evaporate hole injection layer material MoOx on the anode conductive layer to obtain a hole injection layer with a thickness of 10nm;

3. Evaporating the hole transport layer material NPB on the hole injection layer to obtain a hole transport layer with a thickness of 40nm;

4. On the hole transport layer, evaporate the blocking layer material mCP to obtain an exciton blocking layer with a thickness of 15nm;

5. Evaporate the mixture of thermally excited delayed fluorescence host material DPSSPO and DMAC-DPS on the exciton blocking layer, and the thickness of the light emitting layer is 50nm;

6. Continue to vapor-deposit a thermally excited delayed fluorescence host material DPSSPO hole-blocking layer on the light-emitting layer, with a thickness of 40nm hole-blocking layer;

7. Evaporating electron transport layer material Bphen on the hole blocking layer, with a thickness of 80nm electron transport layer;

8. Evaporate LiF, an electron injection layer material, on the electron transport layer, with a thickness of 10nm electron injection layer;

9. Evaporating and depositing a metal cathode conductive layer with a thickness of 10 nm on the electron injection layer to obtain an electroluminescent device.

The metal described in step nine is aluminum.

The thermally excited delayed fluorescence host material in this embodiment 1 is not only the host material of the light-emitting layer of the electroluminescent device, but also the material of the hole blocking layer of the electroluminescent device.

The structure of the electroluminescence device of present embodiment 1 is: ITO/MoOx (10nm)/NPB (40nm)/mCP (15nm)/DPSSPO:DMAC-DPS (20%) 50nm/DPSSPO (40nm)/Bphen (80nm) /LiF(10nm)/Al.

The voltage-current density relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescent host material DPSSPO in Example 1 is shown in Fig. The value voltage is 3.5V.

The voltage-brightness relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescent host material DPSSPO in Example 1 is shown in Figure 16, from which it can be seen that the turn-on voltage of the device is 3.6V.

The luminance-current efficiency relationship curve of the electroluminescent blue light-emitting device prepared with thermally excited delayed fluorescent host material DPSSPO in Example 1 is shown in Figure 17. From this figure, it can be seen that the current efficiency of the device is 123 cd·m ^-2 A maximum value of 31cd·A ^-1 is reached.

The luminance-power efficiency relationship curve of the electroluminescent blue light-emitting device prepared with thermally excited delayed fluorescent host material DPSSPO in Example 1 is shown in Figure 18. From this figure, it can be seen that the device has a power efficiency of 20.31 cd·m ^-2 The efficiency reaches a maximum value of 21lm·W ^-1 .

The luminance-external quantum efficiency relationship curve of the electroluminescent blue light-emitting device prepared with thermally excited delayed fluorescence host material DPSSPO in Example 1 is shown in Figure 19. From this figure, it can be seen that when the luminance of the device is 20.3mA·cm ^-2 , A maximum external quantum efficiency of 14% was obtained.

Figure 20 shows the electroluminescence spectrum of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescence host material DPSSPO in Example 1, from which it can be known that the electroluminescence peak of the device is at 467 nm.

Example 2

Mix 1mmol of 4-bromodiphenylsulfide, 1mmol of diphenylphosphine, 1mmol of anhydrous sodium acetate, 0.001mmol of palladium acetate and 10ml of dried DMF, react at a reaction temperature of 130°C for 10 hours and then pour Quench the reaction in ice water, extract with solvent dichloromethane to obtain an organic layer, and dry the organic layer;

After drying the organic layer, add 1ml H ₂ O ₂ to oxidize, then extract, dry and purify by column chromatography with ethanol and ethyl acetate at a volume ratio of 1:20 to obtain 4-diphenylphosphine Phenylsulfide (4DPSSPO).

Wherein, the molar ratio of said diphenylphosphine to 4-bromodiphenyl sulfide is 1:1, and the ratio of anhydrous sodium acetate to bromodiphenylphosphine sulfide is 1: 1. The molar ratio of palladium acetate to bromodiphenylphosphine sulfide is 0.001:1;

The 4-diphenylphosphinyl sulfide that present embodiment 2 obtains, structural formula II is The data of its proton nuclear magnetic resonance spectrum are:

¹ H-NMR (TMS, CDCl ₃ , 400MHz): δ=7.678-7.627 (m, 4H), 7.557-7.451 (m, 11H), 7.329 (d, J=8.4Hz, 2H), 7.264-7.225ppm ( m, 2H); LDI-TOF: m/z (%): 386 (100) [M ⁺ ].

In Example 2, the ultraviolet fluorescence spectrum of the asymmetric thermal excitation delay fluorescent material 4DPSSPO was obtained, and the phosphorescence spectrum is shown in FIG. 3 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescent host material 4DPSSPO obtained in Example 2 is shown in FIG. 4 . It can be seen from the figure that the cracking temperature of the thermally excited delayed fluorescent host material 4DPSSPO is 339° C.

The method in which the thermal excitation delayed fluorescent host material of this Example 2 is used as the light-emitting layer (and the hole blocking layer) to prepare the electroluminescent device is the same as in Example 1, the difference lies in the thermal excitation delay used in the light-emitting layer and the hole blocking layer. The fluorescent host material is different, and the material used in Example 2 is 4DPSSPO.

In Example 2, the thermally excited delayed fluorescence host material is not only the host material of the light-emitting layer of the electroluminescent device, but also the material of the hole blocking layer of the electroluminescent device.

The structure of the present embodiment 2 electroluminescence device is: ITO/MoOx (10nm)/NPB (40nm)/mCP (15nm)/4DPSSPO:DMAC-DPS (20%) 50nm/4DPSSPO (40nm)/Bphen (80nm)/ LiF(10nm)/Al.

The voltage-current density relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescent host material 4DPSSPO in Example 2 is shown in Fig. The value voltage is 3.6V.

The voltage-brightness relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescent host material 4DPSSPO in Example 2 is shown in Figure 22, from which it can be seen that the turn-on voltage of the device is 3.6V.

The luminance-current efficiency relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescent host material 4DPSSPO in Example 2 is shown in Figure ^23. From this figure, it can be seen that the current The efficiency reaches a maximum value of 31cd·A ^-1 .

The luminance-power efficiency relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescent host material 4DPSSPO in Example 2 is shown in Figure 24. From this figure, it can be seen that the device has a power efficiency of 24.9 cd·m ^-2 The efficiency reaches the maximum value of 21.9lm·W ^-1 .

The luminance-external quantum efficiency relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescence host material 4DPSSPO in Example 2 is shown in Figure ^25. From this figure, it can be seen that the device obtains The maximum external quantum efficiency is 14%.

Figure 26 shows the electroluminescence spectrum of the electroluminescent blue light-emitting device prepared with thermally excited delayed fluorescence host material 4DPSSPO in Example 2, from which it can be known that the electroluminescence peak of the device is at 469 nm.

Example 3

Mix 1mmol of 4,4'-dibromodiphenylsulfide, 2mmol of diphenylphosphine, 2mmol of anhydrous sodium acetate, 0.002mmol of palladium acetate and 10ml of dried DMF, and react at a reaction temperature of 130°C for 10 hours Pour into ice water afterward, extract with solvent dichloromethane to obtain the organic layer, and the organic layer is dried;

After drying the organic layer, add 2ml of H ₂ O ₂ to oxidize, then extract, dry and purify by column chromatography with ethanol and ethyl acetate at a volume ratio of 1:20 to obtain 4,4'-bis(diphenyl Phosphinoxy)ylsulfide (4,4'DPSDPO).

Wherein, the molar ratio of diphenylphosphine and bromodiphenyl sulfide described in the present embodiment 3 is 1:2, and the molar ratio of anhydrous sodium acetate and bromodiphenylphosphine sulfide is 1:2, the molar ratio of palladium acetate to bromodiphenylphosphine sulfide is 0.002:1;

The 4,4'-bis(diphenylphosphineoxy)diphenyl sulfide obtained in the present embodiment 3,

Structural formula III is The data of its proton nuclear magnetic resonance spectrum are:

¹ H-NMR (TMS, CDCl ₃ , 400MHz): δ=7.688–7.535 (m, 16H), 7.482-7.398ppm (q, J _I =5.6Hz; J ₂ =27.2Hz, 12H); LDI-TOF: m/z (%): 586 (100) [M ⁺ ].

The ultraviolet fluorescence spectrum of the thermally excited delayed fluorescence host material 4,4'DPSDPO obtained in Example 3 is shown in FIG. 5 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescence host material 4,4'DPSDPO obtained in Example 3 is shown in Figure 6. It can be seen from the figure that the cracking temperature of 4,4'DPSDPO is 439°C.

The method that the thermally excited delayed fluorescent host material provided in this embodiment 3 is used as the light-emitting layer (and hole blocking layer) to prepare the electroluminescent device is the same as the method used in embodiment 1, and the difference is only that the light-emitting layer (and hole blocking layer) The thermally excited delayed fluorescence host material used in the barrier layer) is different, and the material used in Example 3 is 4,4'DPSDPO.

The structure of the electroluminescence device of present embodiment 3 is:

ITO/MoOx(10nm)/NPB(40nm)/mCP(15nm)/4,4'DPSDPO:DMAC-DPS(20%)50nm/4,4'DPSDPO(40nm)/Bphen(80nm)/LiF(10nm) /Al.

In Example 3, the voltage-current density relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescent host material 4,4'DPSDPO is shown in Figure 27, from which it can be seen that the thermally excited delayed fluorescent host material 4,4' DPSDPO has semiconductor characteristics, and its threshold voltage is 3.6V.

The voltage-brightness relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescent host material 4,4'DPSDPO in Example 3 is shown in Figure 28, from which it can be seen that the turn-on voltage of the device is 3.7V.

The luminance-current efficiency relationship curve of the electroluminescent blue light-emitting device prepared with thermally excited delayed fluorescent host material 4,4'DPSDPO in Example 3 is shown in Figure 29. From this figure, it can be seen that the device has a luminance of 20.31 cd·m When ^-2 , the current efficiency reaches the maximum value of 32cd·A ^-1 .

The luminance-power efficiency relationship curve of the electroluminescent blue light-emitting device prepared by thermally excited delayed fluorescence host material 4,4'DPSDPO in Example 3 is shown in Figure 30, from which it can be seen that the device has a luminance of 22.1 cd·m - ² , the power efficiency reaches a maximum value of 22lm·W- ¹ .

In Example 3, the luminance-external quantum efficiency relationship curve of the electroluminescent blue light-emitting device prepared with thermally excited delayed fluorescence host material 4,4'DPSDPO is shown in Figure 31. From this figure, it can be seen that the device has a luminance of 22.1 cd cm - ² , the maximum external quantum efficiency of 14.5% is obtained.

Figure 32 shows the electroluminescence spectrum of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescence host material 4,4'DPSDPO in Example 3, from which it can be seen that the electroluminescence peak of the device is at 470nm.

Example 4

Mix 1mmol of diphenyl sulfide, 2mmol of tetramethylethylenediamine, 2mmol of n-butyllithium, and 10ml of dry diethyl ether, and react at room temperature for 16 hours. The next day, add 2mmol of Ph ₂ PCl to the reaction system, and react 16 After 1 hour, the product after the reaction was introduced into ice water, extracted, and the organic layer was dried;

After the organic layer was dried, 2ml of H ₂ O ₂ was added to oxidize it, and after extraction and drying, the volume ratio of ethanol and ethyl acetate was 1:20 as the eluent and purified by column chromatography to obtain 2,2'-bis(diphenyl Phosphinoxy) sulfide (DPSDPO).

Wherein the substance molar ratio of n-butyllithium and diphenyl sulfide described in step 2 of the present embodiment 4 is 2:1, and the substance molar ratio of tetramethylethylenediamine and diphenyl sulfide is 2:1, The molar ratio of Ph ₂ PCl to diphenyl sulfide is 2:1.

The diphenylphosphinoxy diphenyl sulfide obtained in the present embodiment 4 is DPSDPO,

Structural formula IV is

The multifunctional modified DPSDPO prepared in this experiment was detected by nuclear magnetic resonance, and the detection results were as follows:

¹ H-NMR (TMS, CDCl ₃ , 400MHz): δ=7.696–7.583(m,10H,),7.425(t,J=6.8Hz,12H),7.215(s,4H),6.819ppm(s,2H ); LDI-TOF: m/z (%): 586 (100) [M ⁺ ].

In Example 4, the ultraviolet fluorescence spectrum of the thermally excited delayed fluorescence host material DPSDPO was obtained, and the phosphorescence spectrum is shown in FIG. 7 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescent host material DPSDPO obtained in Example 4 is shown in FIG. 8 , and it can be seen from the figure that the cracking temperature of the thermally excited delayed fluorescent host material DPSDPO is 401°C.

The thermally excited delayed fluorescent host material obtained in Example 4 is used as the light-emitting layer (and hole blocking layer) for the preparation of electroluminescent devices. The thermally excited delayed fluorescence host material used in layer) is different, and the one used in Example 4 is DPSDPO.

In Example 4, the thermally excited delayed fluorescence host material is not only the host material of the light-emitting layer of the electroluminescent device, but also the material of the hole blocking layer of the electroluminescent device.

The structure of the present embodiment 4 electroluminescence device is: ITO/MoOx (10nm)/NPB (40nm)/mCP (15nm)/DPSDPO:DMAC-DPS (20%) 50nm/DPSDPO (40nm)/Bphen (80nm)/ LiF (10nm)/Al.

The voltage-current density relationship curve of the electroluminescent blue light-emitting device prepared by using the thermally excited delayed fluorescent host material DPSDPO in Example 4 is shown in Figure 33. From this figure, it can be seen that the thermally excited delayed fluorescent host material DPSDPO material has semiconductor characteristics, and its valve The value voltage is 3.6V.

The voltage-brightness relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescent host material DPSDPO in Example 4 is shown in Figure 34, from which it can be seen that the turn-on voltage of the device is 3.7V.

The luminance-current efficiency relationship curve of the electroluminescent blue light-emitting device prepared by the thermally excited delayed fluorescence host material DPSDPO ⁱⁿ Example 4 is shown in Figure 35. From this figure, it can be seen that the current The efficiency reaches a maximum value of 30cd·A ^-1 .

The luminance-power efficiency relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescence host material DPSDPO in Example 4 is shown in Figure 36. From this figure, it can be seen that the power efficiency of the device is 22 cd·m ^-2 A maximum value of 21.6lm·W ^-1 was reached.

In Example 4, the luminance-external quantum efficiency relationship curve of the electroluminescent blue light-emitting device prepared with thermally excited delayed fluorescence host material DPSDPO is shown in Figure 37. From this figure, it can be seen that when the luminance of the device is 130mA·cm ^-2 , the obtained The maximum external quantum efficiency is 14.5%.

Figure 38 shows the electroluminescence spectrum of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescence host material DPSDPO in Example 4, from which it can be seen that the electroluminescence peak of the device is at 467 nm.

Example 5

Add 1mmol of 2-diphenylphosphineoxy-4,4'-dibromodiphenylsulfide, 2mmol of diphenylphosphine, 3mmol of anhydrous sodium acetate, 0.002mmol of palladium acetate and 10ml of dried DMF Mix and pour into ice water after reacting for 10 hours, extract to obtain an organic layer, and dry the organic layer;

After the organic layer was dried, 1ml _H2O2 was added to oxidize it, and after extraction and _drying , the volume ratio of ethanol and ethyl acetate was 1:20 as the eluent and purified by column chromatography to obtain diphenylphosphinoxysulfide ( 2,4,4'DPSTPO).

Wherein, the molar ratio of diphenylphosphine and brominated diphenylphosphinoxydiphenyl sulfide described in Example 5 is 2:1, anhydrous sodium acetate and brominated diphenylphosphinoxydisulfide The molar ratio of ether is 2:1, and the molar ratio of palladium acetate to bromodiphenylphosphinyl sulfide is 0.002:1;

The 2,4,4'-tris(diphenylphosphinoxy)diphenyl sulfide obtained in Example 5 is denoted as 2,4,4'DPSTPO, and the structural formula V is

The data of its proton nuclear magnetic resonance spectrum are:

1H-NMR (TMS, CDCl ₃ , 400MHz): δ=7.770(t, J=10.8Hz, 1H), 7.659–7.470(m, 24H), 7.403-7.295(m, 9H), 7.276-7.164ppm(m ,3H); LDI-TOF: m/z (%): 786 (100) [M+].

The ultraviolet fluorescence spectrum and phosphorescence spectrum of the thermally excited delayed fluorescence host material 2,4,4'DPSTPO obtained in Example 5 are shown in FIG. 9 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescence host material 2,4,4'DPSTPO obtained in Example 5 is shown in Figure 10, from which it can be seen that the cracking temperature of 2,4,4'DPSTPO is 428°C.

The method in which the thermally excited delayed fluorescent host material of this Example 5 is used as the light-emitting layer (and the hole blocking layer) to prepare the electroluminescent device is the same as the method used in Example 1, and the only difference is that the light-emitting layer (and the hole blocking layer) The thermal excitation delayed fluorescence host material of layer) is different, and the material used in Example 5 is 2,4,4'DPSTPO.

The structure of the electroluminescent device in Example 5 is: ITO/MoOx (10nm)/NPB (40nm)/mCP (15nm)/2,4,4'DPSTPO:DMAC-DPS (20%) 50nm/2,4, 4'DPSTPO(40nm)/Bphen(80nm)/LiF(10nm)/Al.

In Example 5, the voltage-current density relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescent host material 2,4,4'DPSTPO is shown in Figure 39, from which it can be seen that the thermally excited delayed fluorescent host material 2, 4,4'DPSTPO material has semiconductor characteristics, and its threshold voltage is 3.5V.

The voltage-brightness relationship curve of the electroluminescent blue light-emitting device prepared with thermally excited delayed fluorescent host material 2,4,4'DPSTPO in Example 5 is shown in Figure 40, from which it can be seen that the turn-on voltage of the device is 3.6V .

The luminance-current efficiency relationship curve of the electroluminescent blue light-emitting device prepared by thermally excited delayed fluorescent host material 2,4,4'DPSTPO in Example 5 is shown in Figure 41, from which it can be seen that the luminance of the device is 453cd·m When ^-2 , the current efficiency reaches the maximum value of 29.1cd·A ^-1 .

The luminance-power efficiency relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescent host material 2,4,4'DPSTPO in Example 5 is shown in Figure 42. From this figure, it can be seen that the device has a luminance of 452cd· When m ^-2 , the power efficiency reaches the maximum value of 16.6lm·W ^-1 .

In Example 5, the brightness-external quantum efficiency relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescent host material 2,4,4'DPSTPO is shown in Figure 43. From this figure, it can be seen that the device has a brightness of 453cd· cm ^-2 , the maximum external quantum efficiency is 13.6%.

Figure 44 shows the electroluminescence spectrum of the electroluminescence phosphorescent device prepared with thermally excited delayed fluorescence host material 2,4,4'DPSTPO in Example 5. From this figure, it can be seen that the electroluminescence peak of the device is at 467nm.

Example 6

Mix 1mmol of 2,2'-diphenylphosphineoxy-4-bromodiphenylsulfide, 1mmol of diphenylphosphine, 1mmol of anhydrous sodium acetate, 0.002mmol of palladium acetate and 5ml of dried DMF was mixed, reacted for 10 hours, poured into ice water, extracted to obtain an organic layer, and the organic layer was dried;

After drying the organic layer, add 1ml H ₂ O ₂ to oxidize, then extract, dry and purify by column chromatography with ethanol and ethyl acetate at a volume ratio of 1:20 as the eluent to obtain diphenylphosphineoxydiphenyl Thioether (2,2',4'DPSTPO).

Wherein, the molar ratio of the diphenylphosphine described in Example 6 to the brominated diphenylphosphinoxysulfide substance is 1:1, and the ratio of anhydrous sodium acetate to the brominated diphenylphosphineoxysulfide substance The molar ratio is 1:1, and the molar ratio of palladium acetate to brominated diphenylphosphinyl sulfide is 0.002:1;

The thermally excited delayed fluorescence diphenyl sulfide aromatic phosphine oxide host material obtained in Example 6 is 2,2',4'DPSTPO, and its structural formula VI is

The thermally excited delayed fluorescence host material 2,2',4'DPSTPO prepared in this experiment was detected by a nuclear magnetic resonance instrument, and the data of its hydrogen nuclear magnetic resonance spectrum are:

¹ H-NMR (TMS, CDCl ₃ , 400MHz): δ=7.766–7.701(m,1H),7.694–7.290(m,34H),7.121-7.130(m,1H),6.709-6.691ppm(m,1H ); LDI-TOF: m/z (%): 786 (100) [M ⁺ ].

The ultraviolet fluorescence spectrum and phosphorescence spectrum of the thermally excited delayed fluorescence host material 2, 2', 4'DPSTPO obtained in Example 6 are shown in Fig. 11 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescence host material 2,2',4'DPSTPO obtained in Example 6 is shown in Figure 12. It can be seen from the figure that the cracking temperature of 2,2',4'DPSTPO is 392°C.

The method in which the thermally excited delayed fluorescent host material of this embodiment 6 is used as the light-emitting layer (and the hole blocking layer) to prepare the electroluminescent device is the same as the method in Example 1, and the only difference is that the light-emitting layer (and the hole blocking layer ) is different from the thermally excited delayed fluorescence host material, and the one used in Example 6 is 2,2',4'DPSTPO.

The structure of the electroluminescence device of present embodiment 6 is:

ITO/MoOx(10nm)/NPB(40nm)/mCP(15nm)/2,2',4DPSTPO:DMAC-DPS(20%)50nm/2,2',4DPSTPO(40nm)/Bphen(80nm)/LiF( 10nm)/Al.

In Example 6, the voltage-current density relationship curve of the electroluminescent blue light-emitting device prepared with thermally excited delayed fluorescent host material 2,2',4DPSTPO is shown in Figure 45. From this figure, it can be seen that the thermally excited delayed fluorescent host material 2,2 ', 4DPSTPO material has semiconductor characteristics, and its threshold voltage is 3.6V.

The voltage-brightness relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescent host material 2,2',4DPSTPO in Example 6 is shown in Figure 46, from which it can be seen that the turn-on voltage of the device is 3.5V.

The luminance-current efficiency relationship curve of the electroluminescent blue light-emitting device prepared with the thermally excited delayed fluorescent host material in Example 6 is shown in Figure 47. From this figure, it can be seen that the current efficiency reaches the maximum when the luminance of the device is 1588 cd·m ^-2 The value is 24cd·A ^-1 .

The luminance-power efficiency relationship curve of the electroluminescent blue light-emitting device prepared by thermally excited delayed fluorescent host material 2,2',4DPSTPO in Example 6 is shown in Figure 48, from which it can be seen that the device has a luminance of 31.66 cd·m When ^-2 , the power efficiency reaches the maximum value of 21.8lm·W ^-1 .

In Example 6, the luminance-external quantum efficiency relationship curve of the electroluminescent blue light-emitting device prepared with thermally excited delayed fluorescent host material 2,2',4DPSTPO is shown in Figure 49. From this figure, it can be seen that the device has a luminance of 1167mA·cm When ^-2 , the maximum external quantum efficiency is 11.3%.

In Example 6, the electroluminescence spectrum of the electroluminescent blue light-emitting device prepared by thermally exciting the delayed fluorescence host material 2,2',4DPSTPO is shown in Figure 50, from which it can be seen that the electroluminescence peak of the device is at 471nm .

Example 7

1mmol of 2,2'-diphenylphosphineoxy-4,4'-dibromodiphenylsulfide, 2mmol of diphenylphosphine, 3mmol of anhydrous sodium acetate, 0.002mmol of palladium acetate and 10ml The dried DMF was mixed, reacted for 10 hours and poured into ice water, extracted to obtain an organic layer, and the organic layer was dried;

After the organic layer was dried, 1ml _H2O2 was added to oxidize it, and after extraction and _drying , the volume ratio of ethanol and ethyl acetate was 1:20 as the eluent and purified by column chromatography to obtain diphenylphosphinoxysulfide ( 2,2',4,4'DPSQPO).

Wherein, the molar ratio of the diphenylphosphine described in Example 7 and the brominated diphenylphosphinoxysulfide substance is 2:1, and the ratio of anhydrous sodium acetate to the brominated diphenylphosphineoxysulfide substance The molar ratio is 2:1, and the molar ratio of palladium acetate to brominated diphenylphosphinyl sulfide is 0.002:1;

In Example 7, the thermally excited delayed fluorescent diphenyl sulfide aromatic phosphine oxide host material is 2,2',4,4'DPSQPO, and the structural formula VII is

The data of the proton nuclear magnetic resonance spectrum of the thermally excited delayed fluorescence host material 2,2',4,4'DPSQPO detected by the nuclear magnetic resonance instrument are as follows:

¹ H-NMR (TMS, CDCl ₃ , 400MHz): δ=7.698–7.650(m,2H),7.526–7.468(m,21H),7.431-7.347(m,14H),7.343-7.272(m,8H) , 7.085-7.052ppm (m, 2H); LDI-TOF: m/z (%): 986 (100) [M ⁺ ]. The ultraviolet fluorescence spectrum and phosphorescence spectrum of the thermally excited delayed fluorescence host material 2,2',4,4'DPSQPO obtained in Example 7 are shown in FIG. 13 .

The thermogravimetric analysis spectrum of the thermally excited delayed fluorescence host material 2,2', 4,4'DPSQPO obtained in Example 7 is shown in Figure 14. It can be seen from the figure that the cracking temperature of 2,2', 4,4'DPSQPO is 427°C.

The method of using the thermally excited delayed fluorescent host material obtained in Example 7 as the light-emitting layer (and hole blocking layer) to prepare an electroluminescent device is the same as that in Example 1, and the only difference is that the light-emitting layer (and hole blocking layer) The thermally excited delayed fluorescence host material used in Example 7 is 2,2',4,4'DPSQPO.

The structure of the electroluminescence device of present embodiment 7 is:

ITO/MoOx(10nm)/NPB(40nm)/mCP(15nm)/2,2',4,4'DPSQPO:DMAC-DPS(20%)50nm/2,2',4,4'DPSQPO(40nm) /Bphen(80nm)/LiF(10nm)/Al.

The voltage-current density relationship curve of the electroluminescent blue light-emitting device prepared by the multifunctional modified 2,2',4,4'DPSQPO in Example 7 is shown in Figure 51, from which it can be seen that 2,2',4 ,4'DPSQPO material has semiconducting properties, and its threshold voltage is 3.6V.

In Example 7, the voltage-brightness relationship curve of the electroluminescent blue light-emitting device prepared with thermally excited delayed fluorescent host material 2,2',4,4'DPSQPO is shown in Figure 52, from which the turn-on voltage of the device can be known is 3.5V.

The luminance-current efficiency relationship curve of the electroluminescent blue light-emitting device prepared by thermally excited delayed fluorescent host material 2,2',4,4'DPSQPO in Example 7 is shown in Figure 53. From this figure, it can be seen that the device has a luminance of At 20.3cd·m ^-2 , the current efficiency reaches the maximum value of 31.4cd·A ^-1 .

The luminance-power efficiency relationship curve of the electroluminescent blue light-emitting device prepared with thermally excited delayed fluorescent host material 2,2',4,4'DPSQPO in Example 7 is shown in Figure 54, from which it can be seen that the device is at When it is 24.9cd·m ^-2 , the power efficiency reaches the maximum value of 21.9lm·W ^-1 .

In Example 7, the luminance-external quantum efficiency relationship curve of the electroluminescent blue light-emitting device prepared by thermally excited delayed fluorescence host material 2,2',4,4'DPSQPO is shown in Figure 55. When it is 24.8cd·cm ^-2 , the maximum external quantum efficiency is 14.1%.

The electroluminescence spectrum of the electroluminescent blue light-emitting device prepared by thermally excited delayed fluorescence host material 2,2',4,4'DPSQPO in Example 7 is shown in Figure 56, from which it can be seen that the electroluminescence of the device is Peak at 465nm.

The electric blue light device prepared by the thermally excited delayed fluorescence host material with diphenyl sulfide as the parent provided by the present invention reduces the turn-on voltage of the electric blue light device to 3.5V, has good thermodynamic stability, and has a cracking temperature of 317 ℃-427℃, the thermally excited delayed fluorescent host material prepared by the present invention can realize ultra-low voltage driven high-efficiency thermally excited delayed fluorescent blue light devices, and its current efficiency reaches a maximum of 32cd·A ^-1 , and its power efficiency reaches a maximum of 22lm·W ^{- 1} . Compared with the research content of the patent CN104876959A previously authorized by the inventor, the thermal excitation delayed fluorescent host material based on diphenyl sulfide provided by the present invention can make the luminous efficiency of the device and brightness are greatly enhanced, which may be due to the higher electron-donating ability of thioethers and their greater ability to interrupt conjugation. In the preparation method, the present invention is also different from the previous patents, which is obtained by the inventor on the basis of a lot of research and exploration.

The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions should not be construed 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 replacements, modifications or improvements can be made to the technical solutions and implementations of the present invention, all of which fall within the scope of the present invention. The protection scope of the present invention shall be determined by the appended claims.

Claims (10)

1. A thermally excited delayed fluorescent host material, characterized in that the host material uses diphenyl sulfide as a host. 2. The thermally excited delayed fluorescence host material according to claim 1, wherein the host is modified by different numbers of aromatic phosphine groups, preferably each benzene ring is modified by 1 to 4 aromatic phosphine groups , more preferably each benzene ring is modified by 1 to 2 aromatic phosphine groups. 3. The thermally excited delayed fluorescent host material according to claim 2, characterized in that, The parent has the following structural formula after being modified by an aromatic phosphine group: Wherein, X, Y, Z, and D are H or Ph ₂ PO, respectively. 4. The preparation method of the thermally excited delayed fluorescent host material according to any one of claims 1 to 3, characterized in that the preparation method comprises the following steps: Step 1-1, mixing the halogenated raw material with diphenyl sulfide as the parent material, diphenylphosphine, sodium acetate, catalyst and solvent I, reacting, and obtaining intermediate I after treatment; In step 1-2, the intermediate I is oxidized and post-treated to obtain the product. 5. preparation method according to claim 4, is characterized in that, In step 1-1, the reaction is carried out for 10 to 36 hours, and the treatment includes quenching with ice water and extraction with solvent II; In step 1-2, the intermediate is preferably oxidized with hydrogen peroxide, and the post-treatment includes quenching, extraction, drying and concentrating the extract, and then subjecting the obtained concentrate to column chromatography, and the eluent used is a mixture of alcohol esters . 6. according to the described preparation method of claim 4 or 5, it is characterized in that, in step 1-1, described halide raw material comprises chloride, bromide, iodide, preferably bromide, more preferably selected from the following one or more: 4-bromodiphenylsulfide, 4,4′-diphenylsulfide, 2-diphenylphosphinyloxy-4,4′-dibromo-diphenylsulfide, 2,2′ - Diphenylphosphinyloxy-4-bromo-diphenylsulfide, 2,2'-diphenylphosphinyloxy-4,4'-dibromo-diphenylsulfide. 7. The preparation method of the thermally excited delayed fluorescent host material according to any one of claims 1 to 3, characterized in that the preparation method comprises the following steps: Step 2-1, reacting diphenyl sulfide with lithium reagent, then adding halogenated diphenylphosphine for reaction, and obtaining intermediate I' after treatment; In step 2-2, the intermediate I' is oxidized and post-treated to obtain the product. 8. The preparation method according to claim 7, characterized in that, in step 2-1, Reaction of diphenyl sulfide with lithium reagent for 10-24 hours, adding halogenated diphenylphosphine for 10-24 hours, the treatment includes quenching with ice water, extraction; Tetramethylethylenediamine was also added prior to the addition of the lithium reagent. 9. according to the described preparation method of claim 7 or 8, it is characterized in that, in step 2-2, intermediate I ' is preferably oxidized with hydrogen peroxide, and the post-treatment includes water quenching, extraction, concentrated extract, and then The concentrate was purified by column chromatography using a mixture of alcohol esters as eluent. 10. The use of the thermally excited delayed fluorescent host material according to one of claims 1 to 3 or the thermally excited delayed fluorescent host material prepared by the method according to one of claims 4 to 9, The host material is applied to a thermally excited delayed fluorescence electroluminescent device, Preferably, the light-emitting device is a thermally excited delayed fluorescence electroluminescent device that can emit blue light, More preferably, the maximum current efficiency reaches 32cd·A ^-1 , and the maximum power efficiency reaches 22lm·W ^-1 .