CN111675693A - A class of D-A light-emitting small molecules containing acridine and phenanthroimidazole and their applications in electroluminescent devices - Google Patents

Abstract

The invention discloses a kind of electron-donor-acceptor D-A type light-emitting small molecules containing acridine and phenanthroimidazole and its application in electroluminescence devices. In the present invention, the acridine electron donor unit and the phenanthroimidazole electron acceptor unit are respectively connected on both sides of the large sterically hindered anthracene unit. Moderate charge transfer leads to the formation of hybrid localized charge transfer (HLCT) excited states, which can achieve high-energy triplet-to-singlet crossover between inverse systems and achieve 100% utilization of excitons. In addition, acridine and phenanthroimidazole have the characteristics of wide band gap, high fluorescence quantum yield, and high carrier mobility, and light-emitting small molecules containing acridine and phenanthroimidazole can be used to prepare high-efficiency blue organic electroluminescence device.

Description

A class of D-A light-emitting small molecules containing acridine and phenanthroimidazole and their application in electroluminescence device application

technical field

The invention belongs to the technical field of organic optoelectronic materials, in particular to a class of D-A type light-emitting small molecules containing acridine and phenanthroimidazole and their application in electroluminescent devices.

Background technique

Organic light-emitting diodes (OLEDs) have attracted extensive attention due to their flexibility, active emission, high efficiency, low-voltage driving, and easy fabrication of large-area devices. OLED related research can be traced back to the 1960s. In 1963, Professor Pope from New York University and others discovered the electroluminescence phenomenon of organic molecule single crystal anthracene for the first time, and then successively appeared some single crystal structure materials. Electroluminescence properties However, due to the high driving voltage of the device at that time, it failed to attract widespread attention. Until 1987, Deng Qingyun and others of Kodak Company of the United States used the sandwich device structure to develop an OLED device with a brightness of 1000cd m ^-2 driven by a 10V DC voltage, which made OLED research obtain an epoch-making development.

The main application prospects of organic light-emitting diodes are in two aspects: one is applied to new types of displays, and the other is applied to solid-state lighting. The luminescent material is the core part of OLED, which determines the luminous color of the device, and determines the device efficiency and device life to a large extent. To achieve a full-color display panel with a high color rendering index, organic light-emitting materials that emit red, green, and blue are required. Compared with green and red light materials, high-efficiency blue fluorescent materials are still scarce. Therefore, the development of new high-performance blue light materials is a research focus of OLED research.

Conventional fluorescent materials can only utilize 25% of singlet excitons to emit light, which greatly limits their luminescent properties. In order to solve the problem of low exciton utilization, phosphorescent materials using triplet excitons, thermally activated delayed fluorescence TADF materials based on triplet inverse intersystem crossing, and triplet-triplet annihilation upconversion based materials have been developed. TTA fluorescent material. However, the first two types of materials rarely have high-efficiency materials that satisfy the blue color coordinate CIEy<0.15. In addition, these two types of materials also face serious efficiency roll-off problems, which are not conducive to practical applications (Science China Chemistry, 2014, 57, 335– 345; Journal of Materials Chemistry C, 2018, 6, 5577-5596). The TTA fluorescent material forms a singlet exciton by fusing two triplet excitons, and the exciton utilization rate is only 62.5%. In addition to the above materials, there is also a class of fluorescent materials with hybridized localized charge transfer excited state characteristics. Such "thermal exciton" materials based on high-energy charge transfer states can realize the inversion from high triplet energy level to singlet energy level. The inter-system crossing can realize 100% utilization of excitons, which provides a new idea for the development of high-performance blue fluorescent materials.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a D-A type light-emitting small molecule containing acridine and phenanthroimidazole and its application in electroluminescent devices.

The purpose of the present invention is to provide a D-A type light-emitting small molecule containing acridine and phenanthroimidazole and its application in electroluminescent devices. Acridine and phenanthroimidazole units are units with wide bandgap, high stability, high fluorescence quantum yield, and high carrier mobility, and have asymmetric molecular structures that can inhibit molecular aggregation. The localized charge transfer excited state luminescence can be improved, and the utilization rate of excitons can be improved, and the constructed small molecules can be used to prepare high-efficiency blue-light organic light-emitting diodes.

The object of the present invention is achieved by at least one of the following technical solutions.

A class of D-A light-emitting small molecules containing acridine and phenanthroimidazole, the chemical structural formula of which satisfies one of the following structures:

In the formula, R is H, F, CN, an alkyl group having 1 to 4 carbon atoms; R' is a methyl group or a phenyl group.

The above-mentioned D-A light-emitting small molecules containing acridine and phenanthroimidazole can be used as light-emitting layers for preparing organic light-emitting diode devices.

Further, the application of the above-mentioned D-A type light-emitting small molecules containing acridine and phenanthroimidazole in organic electroluminescence devices, the device structure of organic electroluminescence is anode/hole injection layer/hole transport layer/luminescence. Layer/electron transport layer/electron injection layer/cathode, wherein the organic light-emitting layer contains at least one light-emitting small molecule containing acridine and phenanthroimidazole. The light-emitting layer is a pure film of light-emitting small molecules containing acridine and phenanthroimidazole or a mixed film of light-emitting small molecules containing acridine and phenanthroimidazole and a host material doped.

The principle of the present invention is as follows: a novel donor-acceptor type blue fluorescent molecule is constructed by using acridine as the electron donor unit and phenanthroimidazole as the electron acceptor unit. This molecule has the characteristics of wide bandgap of acridine unit, high fluorescence quantum yield, high hole mobility and large conjugated rigid structure of phenanthroimidazole, high fluorescence quantum yield, and high electron mobility. In addition, such molecules have moderately strong charge transfer degree, which can form hybrid localized charge transfer state (HLCT) luminescence and improve exciton utilization. In addition, such molecules have asymmetric structures, which can inhibit molecular aggregation and reduce exciton quenching.

In the present invention, the acridine electron donor unit and the phenanthroimidazole electron acceptor unit are respectively connected on both sides of the large sterically hindered anthracene unit. Moderate charge transfer leads to the formation of hybrid localized charge transfer (HLCT) excited states, which can achieve high-energy triplet-to-singlet crossover between inverse systems and achieve 100% utilization of excitons. In addition, acridine and phenanthroimidazole have the characteristics of wide band gap, high fluorescence quantum yield, and high carrier mobility, and light-emitting small molecules containing acridine and phenanthroimidazole can be used to prepare high-efficiency blue organic electroluminescence device.

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

(1) a class of light-emitting small molecules containing acridine and phenanthroimidazole provided by the present invention, the acridine electron donating unit and the phenanthroimidazole electron withdrawing unit are respectively coupled on both sides of the anthracene unit, which has a large steric hindrance, There is a large twist angle between the acceptor units to form a moderately strong charge transfer state, which can be hybridized with the localized state of the molecule to form a hybrid localized charge transfer (HLCT) charge transfer excited state luminescence to achieve high excitation sub-utilization;

(2) A class of light-emitting small molecules containing acridine and phenanthroimidazole provided by the present invention can adjust the steric hindrance and the degree of charge transfer of the molecule by adjusting the coupling sites and end groups of the acridine and phenanthroimidazole units. , and then change the emission spectrum and improve the antisystem crossing from triplet excitons to singlet;

(3) A class of light-emitting small molecules containing acridine and phenanthroimidazole provided by the present invention, acridine and phenanthroimidazole are respectively used as electron donor/acceptor units, and the constructed D-A type molecule has good holes and electrons Injection and transmission capabilities, with the characteristics of bipolar transmission;

(4) A class of D-A light-emitting small molecules containing acridine and phenanthroimidazole provided by the present invention, both acridine and phenanthroimidazole are wide bandgap units, which can construct blue fluorescent molecules that are currently in short supply, and these two units Both have high fluorescence quantum yields and are expected to achieve high efficiency.

Description of drawings

Figure 1 shows the relationship between the Stokes shift of small molecule M3 in different solvents and the solvent polarizability;

Fig. 2 is the electroluminescence spectrum of the small molecule M4 under the doped device structure;

Fig. 3 is the current density-voltage curve of the small molecule M5 under the doped device structure;

FIG. 4 is the current efficiency-current density curve of the small molecule M6 under the doped device structure.

Detailed ways

The specific implementation of the present invention will be further described below with reference to examples, but the implementation and protection of the present invention are not limited thereto. It should be pointed out that, if there are any processes that are not described in detail below, those skilled in the art can realize or understand them with reference to the prior art. If the reagents or instruments used do not indicate the manufacturer, they are regarded as conventional products that can be purchased in the market.

Example 1

Preparation of compound M1

The structural formula and synthetic route of compound M1 are shown in the figure below, and the specific synthetic method is as follows:

(1) Synthesis of Compound 1

Under nitrogen protection, 9,10-dihydro-9,9-diphenylacridine (10mmol), 9,10-dibromoanthracene (10mmol), sodium tert-butoxide (25mmol), catalyst tridibenzylidene Dipalladium acetone (Pd ₂ (dba) ₃ , 0.5 mmol) and ligand tri-tert-butylphosphine (1 mmol) were added to 50 ml of toluene, stirred and heated to 120° C., and reacted for 10 hours. After the reaction, the product was extracted with ethyl acetate, washed three times with saturated sodium chloride solution, and dried with anhydrous sodium sulfate. The dried solution was filtered, and the solvent was spin-dried with a rotary evaporator to obtain a crude product. The crude product was separated and purified by silica gel chromatography, and the eluent was petroleum ether/dichloromethane mixed solvent to obtain a white solid product with a yield of 66%. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product.

(2) Synthesis of compound 2

Under nitrogen protection, phenanthrenequinone (10 mmol), p-bromobenzaldehyde (10 mmol), aniline (10 mmol), and trimethylamine hydrochloride (30 mmol) were added to 80 ml of acetic acid, and heated to reflux for 24 hours. After cooling to room temperature and standing, suction filtration, and the filter residue was washed with ethanol three times to obtain a crude product. Recrystallization from tetrahydrofuran/ethanol mixed solvent gave a white solid product with a yield of 79%. The results of ¹ HNMR, ¹³ CNMR, MS and elemental analysis indicated that the obtained compound was the target product.

(3) Synthesis of compound 3

In a nitrogen atmosphere, compound 2 (10 mmol), pinacol diboronate (12 mmol), potassium acetate (30 mmol), [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride ( 0.5 mmol) was added to 50 ml of 1,4-dioxane, and the temperature was raised to 80° C. and reacted for 12 hours. After completion of the reaction, cooling, vacuum distillation and spin drying of the reaction solvent, extraction with dichloromethane, then washing with saturated sodium chloride solution 3 times, the crude product is purified by column chromatography using petroleum ether/dichloromethane as eluent to obtain White solid product in 81% yield. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product.

(4) Synthesis of compound M1

Under nitrogen protection, compound 1 (10 mmol), compound 3 (10 mmol), potassium carbonate (30 mmol), tetrakis(triphenylphosphine) palladium (0.5 mmol) were dissolved in 50 ml of toluene and 15 ml of water, and then tetrabutyl bromide was added. Ammonium (0.3 mmol) was used as a phase transfer catalyst, and the temperature was raised to 85°C for 8 hours. After the reaction, the toluene solvent was distilled off under reduced pressure, the product was extracted with dichloromethane, washed three times with saturated aqueous sodium chloride solution, the organic phase was removed from the solvent by a rotary evaporator, and the crude product was purified by column chromatography, using silica gel as the immobilizer. phase, and petroleum ether/dichloromethane was used as the mobile phase, and a solid product was obtained after purification with a yield of 73%. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product. The fluorescence quantum yield of compound M1 was determined to be 91% by integrating sphere.

Example 2

Preparation of compound M2

The structural formula and synthetic route of compound M2 are shown in the following figure, and the specific synthetic method is as follows:

(1) Synthesis of compound 4

Under nitrogen protection, 9,10-dihydro-9,9-dimethylacridine (10mmol), 1,4-dibromobenzene (10mmol), sodium tert-butoxide (25mmol), catalyst tridibenzylidene Dipalladium acetone (Pd ₂ (dba) ₃ , 0.5 mmol) and ligand tri-tert-butylphosphine (1 mmol) were added to 50 ml of toluene, stirred and heated to 120° C., and reacted for 10 hours. After the reaction, the product was extracted with ethyl acetate, washed three times with saturated sodium chloride solution, and dried with anhydrous sodium sulfate. The dried solution was filtered, and the solvent was spin-dried with a rotary evaporator to obtain a crude product. The crude product was separated and purified by silica gel chromatography, and the eluent was petroleum ether/dichloromethane mixed solvent to obtain a white solid product with a yield of 73%. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product.

(2) Synthesis of compound 5

Under nitrogen atmosphere, reactant 4 (10 mmol), pinacol diboronate (12 mmol), potassium acetate (10 mmol), [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride were combined (Pd(dppf)Cl ₂ , 0.5 mmol) was added to the reaction and dissolved in 100 mL of 1,4-dioxane, heated to 80° C. and reacted for 12 hours. After the reaction was completed, the reaction was spin-dried, washed with water, and then extracted with dichloromethane. The crude product was purified by column chromatography using petroleum ether/dichloromethane mixed solvent as eluent to obtain a white solid product with a yield of 84%. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product.

(3) Synthesis of compound 6

Under nitrogen protection, compound 5 (10 mmol), 9,10-dibromoanthracene (10 mmol), potassium carbonate (30 mmol), and tetrakis(triphenylphosphine) palladium (0.5 mmol) were dissolved in 50 ml of toluene and 15 ml of water, and then added Tetrabutylammonium bromide (0.3mmol) was used as a phase transfer catalyst, and the temperature was raised to 85°C for 8 hours. After the reaction, the toluene solvent was distilled off under reduced pressure, the product was extracted with dichloromethane, washed three times with saturated aqueous sodium chloride solution, the organic phase was removed from the solvent by a rotary evaporator, and the crude product was purified by column chromatography, using silica gel as the immobilizer. phase, and petroleum ether/dichloromethane was used as the mobile phase, and a white solid product was obtained after purification with a yield of 68%. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product.

(4) Synthesis of compound M2

Under nitrogen protection, compound 6 (10 mmol), compound 3 (10 mmol), potassium carbonate (30 mmol), tetrakis (triphenylphosphine) palladium (0.5 mmol) were dissolved in 50 ml of toluene and 15 ml of water, and then tetrabutyl bromide was added. Ammonium (0.3 mmol) was used as a phase transfer catalyst, and the temperature was raised to 85°C for 8 hours. After the reaction, the toluene solvent was distilled off under reduced pressure, the product was extracted with dichloromethane, washed three times with saturated aqueous sodium chloride solution, the solvent was removed from the organic phase by a rotary evaporator, and the crude product was purified by column chromatography, using silica gel as a fixed solution. phase, and petroleum ether/dichloromethane was used as the mobile phase, and a solid product was obtained after purification with a yield of 83%. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product. The fluorescence quantum yield of compound M2 was determined to be 95% by integrating sphere.

Example 3

Preparation of compound M3

The structural formula and synthetic route of compound M3 are as follows, and the specific synthetic method is as follows:

(1) Synthesis of compound 7

Under nitrogen protection, 9,10-dihydro-9,9-dimethylacridine (10mmol), 1,3-dibromobenzene (10mmol), sodium tert-butoxide (25mmol), catalyst tridibenzylidene Dipalladium acetone (Pd ₂ (dba) ₃ , 0.5 mmol) and ligand tri-tert-butylphosphine (1 mmol) were added to 50 ml of toluene, stirred and heated to 120° C., and reacted for 10 hours. After the reaction, the product was extracted with ethyl acetate, washed three times with saturated sodium chloride solution, and dried with anhydrous sodium sulfate. The dried solution was filtered, and the solvent was spin-dried with a rotary evaporator to obtain a crude product. The crude product was separated and purified by silica gel chromatography, and the eluent was petroleum ether/dichloromethane mixed solvent to obtain a white solid product with a yield of 76%. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product.

(2) Synthesis of Compound 8

Under nitrogen atmosphere, reactant 7 (10 mmol), pinacol diboronate (12 mmol), potassium acetate (10 mmol), [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride were combined (Pd(dppf)Cl ₂ , 0.5 mmol) was added to the reaction and dissolved in 100 mL of 1,4-dioxane, heated to 80° C. and reacted for 12 hours. After the reaction was completed, the reaction was spin-dried, washed with water, and then extracted with dichloromethane. The crude product was purified by column chromatography using petroleum ether/dichloromethane mixed solvent as eluent to obtain a white solid product with a yield of 88%. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product.

(3) Synthesis of compound 9

Under nitrogen protection, compound 8 (10 mmol), 9,10-dibromoanthracene (10 mmol), potassium carbonate (30 mmol), tetrakis(triphenylphosphine) palladium (0.5 mmol) were dissolved in 50 ml of toluene and 15 ml of water, and then added Tetrabutylammonium bromide (0.3mmol) was used as a phase transfer catalyst, and the temperature was raised to 85°C for 8 hours. After the reaction, the toluene solvent was distilled off under reduced pressure, the product was extracted with dichloromethane, washed three times with saturated aqueous sodium chloride solution, the organic phase was removed from the solvent by a rotary evaporator, and the crude product was purified by column chromatography, using silica gel as the immobilizer. phase, and petroleum ether/dichloromethane was used as the mobile phase, and a white solid product was obtained after purification with a yield of 71%. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product.

(4) Synthesis of compound M3

Under nitrogen protection, compound 9 (10 mmol), compound 3 (10 mmol), potassium carbonate (30 mmol), tetrakis(triphenylphosphine) palladium (0.5 mmol) were dissolved in 50 ml of toluene and 15 ml of water, and then tetrabutyl bromide was added. Ammonium (0.3 mmol) was used as a phase transfer catalyst, and the temperature was raised to 85°C for 8 hours. After the reaction, the toluene solvent was distilled off under reduced pressure, the product was extracted with dichloromethane, washed three times with saturated aqueous sodium chloride solution, the organic phase was removed from the solvent by a rotary evaporator, and the crude product was purified by column chromatography, using silica gel as the immobilizer. phase, and petroleum ether/dichloromethane was used as the mobile phase, and the solid product was obtained after purification, and the yield was 89%. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product. The fluorescence quantum yield of compound M3 was determined to be 97% by integrating sphere.

Figure 1 shows the relationship between the Stokes shift and the solvent polarizability of the small molecule M3 in different solvents. It can be found that two straight lines with different slopes can be fitted to the Stokes shift relative to the solvent polarizability, indicating that the molecule There are both localized states and charge transfer states.

Example 4

Preparation of compound M4

The structural formula and synthetic route of compound M4 are shown in the figure below, and the specific synthetic method is as follows

(1) Synthesis of compound 10

Under nitrogen protection, phenanthrenequinone (10 mmol), p-fluorobenzaldehyde (10 mmol), p-bromoaniline (10 mmol), and trimethylamine hydrochloride (30 mmol) were added to 100 ml of acetic acid, and heated to reflux for 24 hours. After cooling to room temperature and standing, suction filtration, and the filter residue was washed with ethanol three times to obtain a crude product. Recrystallization from tetrahydrofuran/ethanol mixed solvent gave a white solid product with a yield of 85%. The results of ¹ H NMR, ¹³ CNMR, MS and elemental analysis indicated that the obtained compound was the target product.

(2) Synthesis of compound 11

In a nitrogen atmosphere, compound 10 (10 mmol), pinacol diboronate (12 mmol), potassium acetate (30 mmol), [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride ( 0.5 mmol) was added to 50 ml of 1,4-dioxane, and the temperature was raised to 80° C. and reacted for 12 hours. After completion of the reaction, cooling, vacuum distillation and spin drying of the reaction solvent, extraction with dichloromethane, then washing with saturated sodium chloride solution 3 times, the crude product is purified by column chromatography using petroleum ether/dichloromethane as eluent to obtain White solid product in 75% yield. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product.

(3) Synthesis of compound M4

Under nitrogen protection, compound 1 (10 mmol), compound 11 (10 mmol), potassium carbonate (30 mmol), tetrakis (triphenylphosphine) palladium (0.5 mmol) were dissolved in 50 ml of toluene and 15 ml of water, and then tetrabutyl bromide was added. Ammonium (0.3 mmol) was used as a phase transfer catalyst, and the temperature was raised to 85°C for 8 hours. After the reaction, the toluene solvent was distilled off under reduced pressure, the product was extracted with dichloromethane, washed three times with saturated aqueous sodium chloride solution, the organic phase was removed from the solvent by a rotary evaporator, and the crude product was purified by column chromatography, using silica gel as the immobilizer. phase, and petroleum ether/dichloromethane was used as the mobile phase, and a solid product was obtained after purification with a yield of 76%. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product. The fluorescence quantum yield of compound M4 was determined to be 90% by integrating sphere.

Example 5

Preparation of compound M5

The structural formula and synthetic route of compound M5 are shown in the figure below, and the specific synthetic method is as follows

(1) Synthesis of compound 12

Under nitrogen protection, phenanthrenequinone (10 mmol), p-cyanobenzaldehyde (10 mmol), p-bromoaniline (10 mmol) and trimethylamine hydrochloride (30 mmol) were added to 100 ml of acetic acid and heated to reflux for 24 hours. After cooling to room temperature and standing, suction filtration, and the filter residue was washed with ethanol three times to obtain a crude product. Recrystallization from tetrahydrofuran/ethanol mixed solvent gave a white solid product with a yield of 75%. The results of ¹ H NMR, ¹³ CNMR, MS and elemental analysis indicated that the obtained compound was the target product.

(2) Synthesis of compound 13

In a nitrogen atmosphere, compound 12 (10 mmol), pinacol diboronate (12 mmol), potassium acetate (30 mmol), [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride ( 0.5 mmol) was added to 50 ml of 1,4-dioxane, and the temperature was raised to 80° C. and reacted for 12 hours. After completion of the reaction, cooling, vacuum distillation and spin drying of the reaction solvent, extraction with dichloromethane, then washing with saturated sodium chloride solution 3 times, the crude product is purified by column chromatography using petroleum ether/dichloromethane as eluent to obtain White solid product in 82% yield. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product.

(3) Synthesis of compound M5

Under nitrogen protection, compound 6 (10 mmol), compound 13 (10 mmol), potassium carbonate (30 mmol), tetrakis(triphenylphosphine) palladium (0.5 mmol) were dissolved in 50 ml of toluene and 15 ml of water, and then tetrabutyl bromide was added. Ammonium (0.3 mmol) was used as a phase transfer catalyst, and the temperature was raised to 85°C for 8 hours. After the reaction, the toluene solvent was distilled off under reduced pressure, the product was extracted with dichloromethane, washed three times with saturated aqueous sodium chloride solution, the organic phase was removed from the solvent by a rotary evaporator, and the crude product was purified by column chromatography, using silica gel as the immobilizer. phase, and petroleum ether/dichloromethane was used as the mobile phase, and a solid product was obtained after purification with a yield of 70%. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product. The fluorescence quantum yield of compound M5 measured by integrating sphere was 94%.

Example 6

Preparation of compound M6

The structural formula and synthetic route of compound M6 are shown in the figure below, and the specific synthetic method is as follows

Under nitrogen protection, compound 9 (10 mmol), compound 13 (10 mmol), potassium carbonate (30 mmol), tetrakis(triphenylphosphine) palladium (0.5 mmol) were dissolved in 60 ml of toluene and 15 ml of water, and then tetrabutyl bromide was added. Ammonium (0.3 mmol) was used as a phase transfer catalyst, and the temperature was raised to 85°C for 8 hours. After the reaction, the toluene solvent was distilled off under reduced pressure, the product was extracted with dichloromethane, washed three times with saturated aqueous sodium chloride solution, the solvent was removed from the organic phase by a rotary evaporator, and the crude product was purified by column chromatography, using silica gel as a fixed solution. phase, and petroleum ether/dichloromethane was used as the mobile phase, and the solid product was obtained after purification, and the yield was 80%. The results of ¹ H NMR, ¹³ C NMR, MS and elemental analysis indicated that the obtained compound was the target product. The fluorescence quantum yield of compound M6 was determined to be 95% by integrating sphere.

Example 7

Fabrication of Undoped Organic Light Emitting Diodes

Take pre-made indium tin oxide (ITO) glass with a square resistance of 15Ω, ultrasonically clean it with acetone, detergent, deionized water and isopropanol in sequence, and treat with plasma for 10 minutes. Then, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzone was sequentially evaporated on the surface of ITO in a vacuum evaporation device with a thickness of 5 nm. phenanthrene (HATCN) as the hole injection layer, 25 nm thick 4,4'-cyclohexylbis[N,N-bis(4-methylphenyl)aniline] (TAPC) as the hole transport layer, 15 nm thick 4 ,4',4"-tris(carbazol-9-yl)triphenylamine (TCTA) as the exciton blocking layer, 20 nm thick light-emitting small molecules containing acridine and phenanthroimidazole as the light emitting layer, 40 nm thick 1, 3,5-Tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) as the electron transport layer, 1 nm thick lithium fluoride (LiF) as the electron injection layer, 100 nm thick aluminum (Al) ) as the cathode. The device structure is: ITO/HATCN/TAPC/TCTA/M1～M3/TPBi/LiF/Al. The luminescent small molecules containing acridine and phenanthroimidazole are compound M1, compound M2 and compound M3 respectively.

The electroluminescence data of the fabricated undoped devices are listed in Table 1.

Table 1 Properties of organic light-emitting devices based on undoped light-emitting layers

It can be found from Table 1 that the OLED devices prepared from these materials have low turn-on voltage, high brightness and current efficiency, and according to the color coordinates, it can be found that these materials all emit pure blue light or deep blue light.

Example 8

Preparation of Doped Organic Light Emitting Diodes

Take pre-made indium tin oxide (ITO) glass with a square resistance of 15Ω, ultrasonically clean it with acetone, detergent, deionized water and isopropanol in sequence, and treat with plasma for 10 minutes. Then, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzone was sequentially evaporated on the surface of ITO in a vacuum evaporation device with a thickness of 5 nm. phenanthrene (HATCN) as a hole injection layer, 40 nm thick N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine ( NPB) as the hole transport layer, 5 nm thick 4,4',4"-tris(carbazol-9-yl)triphenylamine (TCTA) as the exciton blocking layer, 20 nm thick 9'-(1,3- Phenyl) di-9H-carbazole (mCP) and acridine and phenanthroimidazole-containing light-emitting small molecules (10% by mass) mixed film as the light-emitting layer, 40nm thick 1,3,5-tris(1- Phenyl-1H-benzimidazol-2-yl)benzene (TPBi) is used as the electron transport layer, 1 nm thick lithium fluoride (LiF) is used as the electron injection layer, and 100 nm thick aluminum (Al) is used as the cathode. The device structure is: ITO/HATCN/NPB/TCTA/mCP: M4～M6(10%)/TPBi/LiF/Al. The luminescent small molecules containing acridine and phenanthroimidazole are compound M4, compound M5 and compound M6 respectively.

The electroluminescence spectrum of the small molecule M4 under the doped device structure is shown in Figure 2. It can be found that the emission peak of the device is about 460 nm, which is the standard blue light emission; the current density of the small molecule M5 under the doped device structure - The voltage curve is shown in Figure 3. It can be seen from Figure 3 that under the electric field, the maximum emission wavelength of M5 is about 450nm, and the half-peak width of the electroluminescence spectrum is about 65nm, which is a typical blue light emission. A high current density can be obtained, indicating that the molecule has high carrier mobility; the current efficiency-current density curve of the small molecule M6 under the doped device structure is shown in Figure 4. From Figure 4, it can be found that such small molecules The device current is higher, that is, the small molecule has higher current efficiency and smaller efficiency roll-off, indicating that its carrier transport capability is stronger.

The above examples are only preferred embodiments of the present invention, and are only used to explain the present invention, but not to limit the present invention. Changes, substitutions, modifications, etc. made by those skilled in the art without departing from the spirit of the present invention shall belong to the present invention. the scope of protection of the invention.

Claims (7)

1. a D-A type light-emitting small molecule containing acridine and phenanthroimidazole, is characterized in that, its chemical structural formula is one of following structures:

Wherein, R is H, F, CN or alkyl; R' is methyl or phenyl. 2 . The D-A type light-emitting small molecule containing acridine and phenanthroimidazole according to claim 1 , wherein the number of carbon atoms of the alkyl group is 1-4. 3 . 3. The application of the D-A type light-emitting small molecule containing acridine and phenanthroimidazole according to claim 1 in an organic electroluminescent device. 4 . The application of the D-A type light-emitting small molecule containing acridine and phenanthroimidazole according to claim 3 in an organic electroluminescence device, wherein the organic electroluminescence device comprises a light emitting diode device. 5 . 5. the application of the D-A type light-emitting small molecule containing acridine and phenanthroimidazole according to claim 3 in organic electroluminescence device, it is characterized in that, the device structure of described organic electroluminescence is anode/hole Injection layer/hole transport layer/light emitting layer/electron transport layer/electron injection layer/cathode. 6. The application of the D-A type light-emitting small molecule containing acridine and phenanthroimidazole according to claim 4 in an organic electroluminescent device, wherein the light-emitting layer contains the acridine and phenanthroimidazole containing D-A type luminescent small molecules. 7. the application of the D-A type light-emitting small molecule containing acridine and phenanthroimidazole according to claim 4 in organic electroluminescent device, it is characterized in that, described light-emitting layer is the light-emitting containing acridine and phenanthroimidazole Small molecule pure film of small molecule or mixed film doped with light-emitting small molecule containing acridine and phenanthroimidazole and host material.

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