TWI675030B - Devices comprising a bipolar material of 4,6-diphenylsulfone dibenzofuran - Google Patents

Abstract

The invention relates to a device containing a bipolar material of 4,6-diphenylfluorene dibenzofuran, including a cathode, an anode, and an organic layer. The organic layer is a hole transport layer, a hole blocking layer, an electron transport layer, and a light emitting device. One or more of the layers, the organic layer contains a bipolar host material having a structure described by formula (I), wherein R _{1 to} R ₆ represent an alkyl-substituted or unsubstituted acridinyl group , Phenothiazinyl, phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives, hydrogen, halogen, C1-C4 alkyl, and at least one of R _{1 to} R ₆ is Alkyl substituted or unsubstituted acridinyl, phenothiazinyl, phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives. Experiments show that the organic electroluminescent device prepared by using the bipolar host material of the invention has high stability, high current efficiency and external quantum efficiency.

Description

Device containing bipolar material of 4,6-diphenylfluorene dibenzofuran

The invention relates to an organic light emitting diode, in particular to a device containing a bipolar material containing 4,6-diphenylfluorene dibenzofuran, and belongs to the technical field of organic light emitting materials.

Compared with the characteristics of liquid crystal displays that require backlight, organic light emitting diodes (OLEDs) have the characteristics of active light emission, fast response speed, low energy consumption, high brightness, wide viewing angle, and flexibility, and have great application prospects in the field of flat display , Has been highly valued by academia and industry, so it is regarded as one of the most promising products in the 21st century. At present, OLED devices have achieved mass production and are widely used in electronic products such as mobile phones, tablet computers, car meters, and wearable devices. Electrofluorescence and electrophosphorescence are referred to as first and second generation OLEDs, respectively. OLEDs based on fluorescent materials have the characteristics of high stability, but are limited by the laws of quantum statistics. The ratio of singlet excitons and triplet excitons generated by electrical activation is 1: 3, so fluorescent materials The maximum quantum efficiency in electroluminescence is only 25%. The phosphorescent material has a spin-orbit coupling effect of heavy atoms, which can comprehensively use singlet excitons and triplet excitons, and the theoretical internal quantum efficiency can reach 100%. However, phosphorescent-based OLEDs have significant efficiency roll-off effects in applications, and have certain obstacles in high-brightness applications.

Phosphorescent materials can use singlet excitons and triplet excitons in combination to achieve 100% internal quantum efficiency. Studies have shown that due to the relatively long exciton lifetime of transition metal complexes, the presence of triplet exciton accumulation at high current density can cause triplet-triplet annihilation (TTA), triplet-pole extinction (TPA) , Resulting in phenomena such as efficiency roll-off. To overcome this problem, researchers often dope phosphorescent materials into organic host materials, such as doped in bipolar host materials, to better balance the carrier injection. Recently, materials with thermally active delayed fluorescent materials have also been applied to the body of phosphorescent devices. Due to the small singlet-triplet energy level difference of thermally active delayed fluorescent materials, triplet excitons can pass through the intersystem Crossover to the singlet state, and then transferred to the guest material through Förster resonance energy transfer (FRET), thereby reducing the triplet exciton concentration, and its device performance is also improved. Therefore, for efficient organic light-emitting diodes, it is important to develop high-performance host materials.

At present, the host material widely used in phosphorescent devices is CBP (4,4'-bis (9-carbazolyl) biphenyl), but it requires a higher driving voltage and a lower glass transition temperature (Tg) (Tg = 62 ℃), easy to crystallize. In addition, CBP is a P-type material. The hole mobility is much higher than the electron mobility, which is not conducive to carrier injection and transport balance, and has low luminous efficiency.

The present invention provides a device containing a bipolar material of 4,6-diphenylfluorene dibenzofuran. Since the bipolar material uses 4,6-diphenylfluorene dibenzofuran as the core for pulling electrons, it has the ability to donate electrons. Derivatives such as diphenylamines, carbazoles, acridine, etc., as the linking group, form a DALAD-type bipolar material, which has a higher glass transition temperature and good thermal stability of the host material. Therefore, the present invention contains a bipolar host material The prepared organic electroluminescent device has high stability.

A device containing a 4,6-diphenylfluorene dibenzofuran bipolar material includes a cathode, an anode, and an organic layer, and the organic layer is a hole transport layer, a hole blocking layer, an electron transport layer, or a light emitting layer. One or more layers, the organic layer contains a bipolar host material based on 4,6-diphenylfluorene dibenzofuran, and the bipolar host material has a structure described by formula (I), (I)

Wherein, R _{1 to} R ₆ represent alkyl substituted or unsubstituted acridinyl, phenothiazinyl, phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives, hydrogen , Halogen, C1-C4 alkyl, and at least one of R _{1 to} R ₆ is alkyl substituted or unsubstituted acridinyl, phenothiazinyl, phenoxazinyl, carbazole, indencarbazole, diphenylamine Or other aromatic diphenylamine derivatives.

Preferably: two of R ₁ , R ₂ and R ₃ are hydrogen, halogen or C1-C4 alkyl, and the other is C1-C8 alkyl substituted or unsubstituted acridinyl, phenothiazinyl, phenoxazinyl , Carbazole, indencarbazole, diphenylamine, or other aromatic diphenylamine derivatives; two of R ₄ , R ₅ , and R ₆ are hydrogen, halogen, or C1-C4 alkyl, and the other is C1-C8 alkyl Substituted or unsubstituted acridinyl, phenothiazinyl, phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives.

Preferably: R ₁ and R _{4 are the} same, R ₂ and R _{5 are the} same, and R ₃ and R _{6 are the} same.

Preferably: wherein R ₂ , R ₃ , R ₅ , and R ₆ are hydrogen, halogen, or C1-C4 alkyl, and R ₁ and R ₄ are C1-C4 alkyl-substituted or unsubstituted acridinyl, phenothiazinyl , Phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives.

Preferably: wherein R ₂ , R ₃ , R ₅ , and R ₆ are hydrogen, and R ₁ and R ₄ are C1-C4 alkyl-substituted or unsubstituted acridinyl, carbazole, and indencarbazole.

The compound of formula (I) has one of the following structures: .

An organic electroluminescent device includes a cathode, an anode, and an organic layer. The organic layer is one or more of a hole transporting layer, a hole blocking layer, an electron transporting layer, and a light emitting layer. It should be particularly pointed out that the above-mentioned organic layers can be according to requirements, and these organic layers do not need to exist in each layer.

The compound according to the formula (I) is a material of a light emitting layer.

The total thickness of the organic layer of the electronic device of the present invention is 1-1000 nm, preferably 1-500 nm, and more preferably 5-300 nm.

The organic layer may be formed into a thin film by evaporation or spin coating.

As mentioned above, the compounds of formula (I) of the present invention are as follows, but are not limited to the enumerated structures: .

The preparation method of the above bipolar host material includes the following preparation steps: First, dibenzofuran (a) is formed into a lithium salt under the condition of n-butyllithium, and then 4,6-diiododibenzofuran (b ), And then with halogenated thiophenol (fluorinated, brominated) through the Ullmann reaction to obtain the thioether intermediate (c); the halogenated thioether intermediate is oxidized to obtain the halogenated thiosulfur compound (d); and finally the halogenated thiosulfur compound The compound (d) and a substituted or unsubstituted acridine, carbazole, diphenylamine (e) and the like are catalyzed by a Buchwald reaction or a nucleophilic substitution reaction to obtain the bipolar host material.

Experiments show that the compound of the present invention has a higher glass transition temperature than the commonly used host material CBP, and the present invention significantly improves the thermal stability of the host material. The organic electroluminescence device prepared by using the bipolar host material of the present invention has high stability, high current efficiency and external quantum efficiency, and the material is more in line with the requirements of the organic light emitting diode for the host material.

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

Example 1

(1) The synthetic route of 4,6-diiododibenzofuran (b) is shown below: The specific synthesis steps are as follows: Dibenzofuran (8.41 g, 50 mmol) is weighed into a three-necked flask, protected by nitrogen, added to dry ether (150 mL), and the flask is placed in a -78 ° C low temperature reactor, and slowly dropped Add n-butyllithium (2.2 M, 68 mL, 150 mmol). After the addition is complete, the reaction system is slowly warmed to room temperature and stirring is continued for 10 h. The temperature was lowered to -78 ° C, and a tetrahydrofuran solution (38 g, 150 mmol) of I ₂ was slowly added dropwise. After the dropwise addition was completed, the mixture was stirred at room temperature for 4 h. After the reaction, 10% NaHSO ₃ solution (100 mL) was added, and the layers were extracted. The inorganic phase was extracted with dichloromethane (3 * 50 mL). The organic phase was collected, dried over anhydrous MgSO ₄ and the solution was dried to obtain a crude product. Ethanol was used for pulping, suction filtration and drying were performed to obtain 14 g of a white solid. Yield: 67%.

(2) The synthetic route of 4,6-bis [(4-fluorophenyl) thio] dibenzo [b, d] furan (c1) is shown below: The specific synthetic steps are: Weigh 4,6-diiododibenzofuran (b) (5.25 g, 12.5 mmol), 4-fluorothiophenol (3.27 g, 25.5 mmol), CuI (0.48 g, 2.5 mmol) In a 100 mL three-necked flask, phenanthroline (0.9 g, 5 mmol) and potassium carbonate (4.8 g, 35 mmol) were replaced with nitrogen three times. Dry DMSO was added, and the temperature was raised to 130 ° C for 16 hours. After the reaction was completed, 150 mL of water was added and extracted with dichloromethane (3 * 50 mL). The organic layers were combined and dried over anhydrous magnesium sulfate. Filter through a sand core funnel, spin dry the solvent, beat with ethanol, and dry with suction filtration to obtain 4.43 g of a white powder solid. Yield: 84.6%.

(3) The synthetic route of 4,6-bis [(4-fluorophenyl) fluorenyl] dibenzo [b, d] furan (d1) is shown below: The specific synthetic steps are: Weigh 4,6-bis [(4-fluorophenyl) thio] dibenzo [ b , d ] furan ( c1 ) (1 g, 2.38 mmol) in a flask and dissolve in dichloromethane The reaction system was placed in an ice bath, 2.2 equivalents of m-chloroperoxybenzoic acid was slowly added, and the reaction was carried out at room temperature for 24 hours. After the reaction, 50 mL of a 5% NaHSO ₃ solution was added, and extracted with dichloromethane (3 * 50 mL). The organic layers were combined, washed with a Na ₂ CO ₃ solution, and dried over anhydrous magnesium sulfate. Filter through a sand core funnel, spin dry the solvent, beat with ethanol, and filter and dry to obtain 1.02 g of a white powder solid. Yield: 88.7%.

(4) Synthesis of 4,6-bis [(4- (9,9'-dimethylacridin-10 (9H) -yl) phenylfluorenyl] dibenzo [b, d] furan (1) The synthetic route is as follows: The specific synthetic steps are: Weigh 9,9 'dimethylacridine (0.89 g, 4.2 mmol) into a 50 mL flask, add 10 mL of dry DMF, and slowly add NaH (60%, 0.21 g, 5.2 at 0 ° C) mmol), stirred at room temperature for 30 min, and then added 4,6-bis [(4-fluorophenyl) fluorenyl] dibenzo [b, d] furan (d1) (1 g, 2.06 mmol) in one portion and reacted Stir at 60 ° C for 6 hours. After the reaction was completed, 20 mL of water was added, and a solid precipitated out, filtered with suction, washed with water, and dichloromethane: n-hexane = 2: 1 was used as an eluent. 1.4 g of a yellow solid was separated by silica gel column chromatography. Yield: 78.6%. Product identification information is as follows: ¹ H NMR (400MHz, CDCl ₃ ) δ = 8.73 (d, J = 8.0 Hz, 4 H), 8.27 (d, J = 8.0 Hz, 4 H), 7.65-7.59 (m, 6 H ), 7.44-7.42 (m, 4 H), 6.95-6.93 (m, 8 H), 6.34-6.31 (m, 4 H), 1.63 (s, 6 H), 1.57 (s, 6 H) ppm. ¹³ C NMR (100MHz, CDCl ₃ ) = 147.1, 140.1, 131.7, 131.0, 130.5, 128.0, 126.2, 125.0, 124.0, 121.5, 115.2, 30.7 ppm. Ms (ESI: Mz 863) (M + 1)

Example 2

(1) The synthetic route of 4,6-bis [(4- (9H-carbazole-9-yl) phenylfluorenyl] dibenzo [b, d] furan (2) is shown below: The specific synthesis steps are as follows: Weigh carbazole (1.7 g, 10 mmol) into a 50 mL flask, add 20 mL of dry DMF, slowly add NaH (60%, 0.6 g, 15 mmol) at 0 ° C, and stir at room temperature for 30 minutes. After that, 4,6-bis [(4-fluorophenyl) fluorenyl] dibenzo [b, d] furan (d1) (3 g, 5 mmol) was added in one portion, and the reaction was stirred at 60 ° C. for 6 hours. After the reaction was completed, 60 mL of water was added, and a solid precipitated out, filtered with suction, washed with water, and dichloromethane: n-hexane = 2: 1 was used as an eluent. Silica gel column chromatography separated 3.3 g of a yellow solid. Yield: 85.7%. Product identification information is as follows: ¹ H NMR (400MHz, CDCl ₃ ) δ = 8.62 (d, J = 8.0 Hz, 4 H), 8.66 (d, J = 8.0 Hz, 2 H), 8.23 (d, J = 8.0 Hz , 2 H), 8.15 (d, J = 8.0 Hz, 4 H), 7.93 (d, J = 8.0 Hz, 4 H), 7.72 (t, J = 8.0 Hz, 2 H), 7.44 (d, J = 8.0 Hz, 4 H), 7.30 (t, J = 8.0 Hz, 4 H), 7.22 (t, J = 8.0 Hz, 4 H) ppm. ¹³ C NMR (100MHz, CDCl ₃ ) = 141.9, 138.9, 129.8, 128.1, 127.6, 126.7, 126.2, 124.7, 124.5, 123.0, 120.6, 120.3, 110.3, 109.6 ppm. Ms (ESI: Mz 779) (M + 1)

Example 3

(1) The synthetic route of 4,6-bis [(3-bromophenyl) thio] dibenzo [b, d] furan (c2) is shown below: The specific synthetic steps are: Weigh 4,6-diiododibenzofuran ( b ) (1.05 g, 2.5 mmol), 3-bromothiophenol (0.98 g, 5.2 mmol), CuI (0.095 g, 0.5 mmol) In a 50 mL three-necked flask, phenanthroline (0.18 g, 1 mmol) and potassium carbonate (0.96 g, 7 mmol) were replaced with nitrogen three times. Add 10 mL of dry DMSO, and heat to 130 ° C for 16 hours. After the reaction was completed, 150 mL of water was added and extracted with dichloromethane (3 * 20 mL). The organic layers were combined and dried over anhydrous magnesium sulfate. Filter through a sand core funnel, spin dry the solvent, and separate by silica gel column chromatography with n-hexane / ethyl acetate = 20/1 eluent to obtain 0.9 g of a white solid. Yield: 66%.

(2) The synthetic route of 4,6-bis [(3-bromophenyl) fluorenyl] dibenzo [b, d] furan (d2) is shown below: The specific synthetic steps are: Weigh 4,6-bis [(3-bromophenyl) thio] dibenzo [ b , d ] furan ( c2 ) (0.9 g, 1.66 mmol) in a flask and dissolve in dichloromethane The reaction system was placed in an ice bath, 2.2 equivalents of m-chloroperoxybenzoic acid was slowly added, and the reaction was carried out at room temperature for 24 hours. After the reaction, 50 mL of a 5% NaHSO ₃ solution was added, and extracted with dichloromethane (3 * 50 mL). The organic layers were combined, washed with a Na ₂ CO ₃ solution, and dried over anhydrous magnesium sulfate. Filter through a sand core funnel, spin dry the solvent, beat with ethanol, and dry with suction filtration to obtain 0.8 g of a white powder solid. Yield: 80%.

(3) The synthetic route of 4,6-bis [(3- (9H-carbazole-9-yl) phenylfluorenyl] dibenzo [b, d] furan (3) is shown below: The specific synthetic steps are: Weigh 4,6-bis [(3-bromophenyl) fluorenyl] dibenzo [ b , d ] furan ( d2 ) (0.136 g, 0.3 mmol), carbazole (0.1 g, 0.6 mmol), Pd ₂ (dba) ₃ (28 mg, 0.03 mmol), P ( t Bu) ₃ toluene solution (24 mg, 0.06 mmol), sodium tert-butoxide (0.115 g, 1.2 mmol), toluene 5 mL in 10 mL In a mL Schlenk bottle, protected by nitrogen and reacted at 110 ° C for 10 hours. After the reaction was completed, 20 mL of a 5% NaHSO ₃ solution was added, and extracted with dichloromethane (3 * 20 mL), n-hexane / ethyl acetate = 2: 1 was used as the eluent, and 0.18 g of a yellow solid was separated by silica gel column chromatography. Yield: 69%. Product identification information is as follows: Ms (ESI: Mz 779) (M + 1)

Example 4

(1) The synthetic route of 4,6-bis [(2-bromophenyl) thio] dibenzo [b, d] furan (c3) is shown below: The specific synthetic steps are: Weigh 4,6-diiododibenzofuran ( b ) (2.1 g, 5 mmol), 2-bromothiophenol (1.96 g, 10.4 mmol), CuI (0.19 g, 1 mmol) In a 50 mL three-necked flask, phenanthroline (0.36 g, 2 mmol) and potassium carbonate (2 g, 14 mmol) were replaced with nitrogen three times. 20 mL of dry DMSO was added, and the temperature was raised to 130 ° C for 15 hours. After the reaction was completed, 150 mL of water was added and extracted with dichloromethane (3 * 30 mL). The organic layers were combined and washed with water, and dried over anhydrous magnesium sulfate. Filter through a sand core funnel, spin dry the solvent, and separate by silica gel column chromatography with n-hexane / ethyl acetate = 20/1 eluent to obtain 1.5 g of a white solid. Yield: 55%.

(2) The synthetic route of 4,6-bis [(2-bromophenyl) fluorenyl] dibenzo [b, d] furan (d3) is shown below: The specific synthetic steps are: Weigh 4,6-bis [(2-bromophenyl) thio] dibenzo [ b , d ] furan ( c3 ) (1.4 g, 2.58 mmol) in a flask and dissolve in dichloromethane The reaction system was placed in an ice bath, 2.2 equivalents of m-chloroperoxybenzoic acid was slowly added, and the reaction was carried out at room temperature for 24 hours. After the reaction, 50 mL of a 5% NaHSO ₃ solution was added, and extracted with dichloromethane (3 * 50 mL). The organic layers were combined, washed with a Na ₂ CO ₃ solution, and dried over anhydrous magnesium sulfate. Filter through a sand core funnel, spin dry the solvent, beat with ethanol, and dry with suction filtration to obtain 1.4 g of a white powder solid. Yield: 89%.

(3) The synthetic route of 4,6-bis [(2- (9H-carbazole-9-yl) phenylfluorenyl] dibenzo [b, d] furan (4) is shown below: The specific synthetic steps are: Weigh 4,6-bis [(2-bromophenyl) fluorenyl] dibenzo [ b , d ] furan ( d3 ) (1.36 g, 3 mmol), carbazole (1 g, 6 mmol), Pd ₂ (dba) ₃ (0.28g, 0.3 mmol), P ( t Bu) ₃ toluene solution (0.24 g, 0.6 mmol), sodium tert-butoxide (1.15 g, 12 mmol), toluene 10 mL In a 25 mL Schlenk bottle, under nitrogen protection, react at 110 ° C for 10 hours. After the reaction was completed, 30 mL of a 5% NaHSO ₃ solution was added, and extracted with dichloromethane (3 * 30 mL), n-hexane / ethyl acetate = 2: 1 as an eluent, and 1.1 g of a yellow solid was separated by silica gel column chromatography. Yield: 47%. Product identification information is as follows: Ms (ESI: Mz 779) (M + 1)

Embodiment Example 5 Glass transition temperature test: Under nitrogen, a heating and cooling rate of 20 ^o C / min by differential scanning calorimetry (DSC) test compound 2 glass transition temperatures. Compounds measured glass transition temperature T _g of 2 to 180 ^o C (FIG. 1). The glass transition temperature of CBP reported in the literature is only 62 ^o C. It can be seen that the compound in the present invention has a higher glass transition temperature than the commonly used host material CBP, and the present invention significantly improves the thermal stability of the host material.

Example 6

The structure of the organic electroluminescent device is ITO / HATCN (5 nm) / TAPC (50 nm) / Compound 2: Ir (ppy) :( 4 wt%, 20 nm) / TmPyPb (50 nm) / LiF (1 nm) / AL (100 nm)

The device preparation method is described as follows: See Figure 2. First, the transparent conductive ITO glass substrate (including 10 and 20) is processed according to the following steps: washed with detergent solution, deionized water, ethanol, acetone, deionized water in advance, and then Oxygen plasma treatment for 30 seconds. Then, 5 nm thick HATCN was evaporated as a hole injection layer 30 on ITO. Then, a 50 nm thick TAPC was evaporated as a hole transport layer 40 on the hole injection layer. Then, 20 nm thick compound 2: Ir (ppy) :( 4wt%) was evaporated on the hole transport layer as the light emitting layer 50. Then, a 50 nm-thick TmPyPb was evaporated on the light emitting layer as the electron transporting layer 60. Then, 1 nm-thick LiF was evaporated on the electron transport layer as the electron injection layer 70. Finally, 100 nm thick aluminum was evaporated on the electron injection layer as the device cathode 80.

Comparative example

The structure of the electroluminescent device is ITO / HATCN (5 nm) / TAPC (50 nm) / CBP: Ir (ppy) :( 4 wt%, 20 nm) / TmPyPb (50 nm) / LiF (1 nm) / AL (100 nm)

The method is the same as that of Example 6, except that a commercially available compound CBP is used as a host material to make an electroluminescent organic semiconductor diode device for comparison.

Experiments show that the electroluminescent device prepared by using the bipolar host material of the present invention has a voltage of 6.99 V, a brightness of 7082 cd / m ² , a current efficiency of 35.41 cd / A, and a power efficiency of 15.91 at a current density of 20 mA / cm ^2. lm / W, the external quantum efficiency EQE is 9.98%; and the electroluminescent device prepared using a commercially available host CBP at the same current density, voltage is 7.71 V, brightness is 5845 cd / m ² , current efficiency is 29.23 cd / A, power The efficiency is 11.91 lm / W, and the external quantum efficiency EQE is 8.5%. Therefore, by using the bipolar host material of the present invention, a current efficiency of 21% and an external quantum efficiency of 17.4% higher than that of a device prepared by CBP can be obtained, a higher device stability can be obtained, a better application prospect is more consistent with Organic light-emitting diode requirements for host materials.

Figure 1 shows the DSC curve of compound 2. FIG. 2 is a device structure diagram of the present invention, where 10 represents a glass substrate, 20 represents an anode, 30 represents a hole injection layer, 40 represents a hole transport layer, 50 represents a light emitting layer, 60 represents an electron transport, and 70 Represented by the electron injection layer, 80 represents the cathode.

Claims (10)

A device containing a bipolar material of 4,6-diphenylfluorene dibenzofuran includes a cathode, an anode, and an organic layer. The organic layer is a hole transport layer, a hole blocking layer, an electron transport layer, and a light emitting layer. One or more layers, the organic layer contains a bipolar host material based on 4,6-diphenylfluorene dibenzofuran, and the bipolar host material has a structure according to formula (I), (I) wherein R _{1 to} R ₆ represent alkyl substituted or unsubstituted acridinyl, phenothiazinyl, phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives was hydrogen, halogen, C1-C4 alkyl group, and R ₁ -R ₆ is an alkyl group having at least one substituted or unsubstituted acridinyl, phenothiazine group, phenoxazine group, carbazole, indenocarbazole , Diphenylamine or other aromatic diphenylamine derivatives. The device according to item 1 of the scope of patent application, wherein two of R ₁ , R ₂ , and R ₃ are hydrogen, halogen, or C1-C4 alkyl, and the other is C1-C8 alkyl-substituted or unsubstituted acridine , Phenothiazinyl, phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives; two of R ₄ , R ₅ , and R ₆ are hydrogen, halogen, or C1-C4 Alkyl, the other is C1-C8 alkyl substituted or unsubstituted acridinyl, phenothiazinyl, phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives. According to the device described in the second item of the patent application, wherein R ₁ and R _{4 are the} same, R ₂ and R _{5 are the} same, and R ₃ and R _{6 are the} same. The device according to item 3 of the scope of patent application, wherein R ₂ , R ₃ , R ₅ , and R ₆ are hydrogen, halogen, or C1-C4 alkyl, and R ₁ and R ₄ are C1-C4 alkyl substituted or unsubstituted Acridinyl, phenothiazinyl, phenoxazinyl, carbazole, indencarbazole, diphenylamine or other aromatic diphenylamine derivatives. The device according to item 4 of the scope of patent application, wherein R ₂ , R ₃ , R ₅ , and R ₆ are hydrogen, and R ₁ and R ₃ are C1-C4 alkyl-substituted or unsubstituted acridinyl, carbazole, Indencarbazole. The device according to item 1 of the scope of patent application, wherein the formula (I) is one of the following structures: . The device according to item 6 of the scope of patent application, wherein the formula (I) is one of the following structures: . According to the device described in item 1 of the patent application scope, the bipolar host material based on 4,6-diphenylfluorene dibenzofuran is a material of a light emitting layer. According to the device described in claim 1, the total thickness of the organic layer is 1-1000 nm. According to the device described in claim 1, the organic layer is formed into a thin film by evaporation or spin coating.