2,4-diazafluorene derivatives and electronic devices

Abstract

The present application relates to 2,4-diazafluorene derivatives and electronic devices. The 2,4-diazafluorene derivatives of the present application have good film-forming property and thermal stability by introducing 2,4-diazafluorene derivative structure, and can be used for preparing organic electroluminescent devices. The 2,4-diazafluorene derivatives of the present application can be used as the constituent material of the light-emitting layer, the hole-blocking layer or the electron-transporting layer, and can reduce the driving voltage, improve the efficiency, brightness and lifetime, etc.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic optoelectronic materials, and relates to a 2,4-difluoro derivative and an electronic device comprising the 2,4-difluoro derivative. More particularly, the present application relates to a 2,4-difluoro derivative suitable for use in electronic devices, particularly organic electroluminescent devices, and an electronic device using the 2,4-difluoro derivative. BACKGROUND

[0002] An organic electroluminescent device has a series of advantages such as self-luminescence, low-voltage driving, full solidification, wide viewing angle, simple composition and process, and the like. Compared with a liquid crystal display, the organic electroluminescent device does not need a backlight. Therefore, the organic electroluminescent device has a wide application prospect.

[0003] An organic electroluminescent device generally comprises an anode, a metal cathode and an organic layer sandwiched therebetween. The organic layer mainly comprises a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer and an electron injection layer. In addition, the light-emitting layer mostly adopts a host-guest structure. That is, a light-emitting material is doped in a host material at a certain concentration to avoid concentration quenching and triplet-triplet annihilation, and to improve the light-emitting efficiency. Therefore, the host material is generally required to have a high triplet energy level and at the same time have high stability.

[0004] At present, the research on organic electroluminescent materials has been widely carried out in the academic and industrial circles, and a large number of organic electroluminescent materials with excellent performance have been developed. Overall, the future direction of organic electroluminescent devices is to develop white light devices and full-color display devices with high efficiency, long service life and low cost, but the industrialization process of this technology still faces many key problems. Once the organic material crystallizes, the charge hopping mechanism between molecules will be different, resulting in a decrease in the transport performance compared with the amorphous thin film mechanism, causing an imbalance in the electron and hole mobility of the device. Therefore, it is of great practical application value to design and develop stable and efficient organic materials that can improve the glass transition temperature, reduce the threshold voltage and prolong the service life of the device. As a new type of material for organic electroluminescent devices to overcome the deficiencies in practical application, it is the focus and future research trend of the research on organic electroluminescent device materials. SUMMARY

[0005] One of the objects of the present application is to provide a 2,4-difluoro derivative represented by the following general formula (I):

[0006]

[0007] wherein R 1 , R 2may each independently represent a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms;

[0008] R 1 , R 2 may each independently represent a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms;

[0009] R 1 , R 2 may each independently represent a substituted or unsubstituted alkynyl group having 2 to 20 carbon atoms;

[0010] R 1 , R 2 may each independently represent a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms;

[0011] R 1 , R 2 may each independently represent a substituted or unsubstituted aromatic heterocyclic group having 5 to 30 carbon atoms;

[0012] R 1 , R 2 may each independently represent a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a cyano group, NO2, N(R)2, OR, SR, C(=O)R, P(=O)R, Si(R)3; wherein R represents a hydrogen atom, a deuterium atom, a fluorine atom, a chlorine atom, a bromine atom, a cyano group, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms; a substituted or unsubstituted alkenyl group having 2 to 20 carbon atoms; a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms; or a substituted or unsubstituted aromatic heterocyclic group having 5 to 30 carbon atoms;

[0013] when R 1 , R 2 is an aromatic hydrocarbon group or an aromatic heterocyclic group, it can be linked in a fused ring manner with the adjacent benzene ring.

[0014] Further, R 1 , R 2 each independently represent a phenyl group, a biphenyl group, a terphenyl group, a quaterphenyl group, a quinquephenyl group, a benzothienocarbazole group, a benzo-furanocarbazole group, a benzofluorene-carbazole group, a benzanthracene group, a benzo-phenanthrene group, a fluorene group, a spiro-bisfluorene group, a triazine group, a dibenzofuran group, a dibenzothiophene group, a carbazole group, an N-phenylcarbazole group, an indenocarbazole group, a benzimidazole group, a diphenyl-benzimidazole group, a diphenyl-oxadiazole group, a diphenyl-boronyl group, a triphenyl-phosphorinyl group, a diphenyl-phosphorinyl group, a triphenyl-silyl group, or a tetraphenyl-silyl group.

[0015] Further, the aromatic hydrocarbon group or the aromatic heterocyclic group is selected from the group consisting of phenyl, naphthyl, anthryl, benzanthryl, phenanthryl, benzphenanthryl, pyrenyl, perylenyl, fluoranthenyl, benzofluoranthenyl, tetracenyl, pentacenyl, benzopyrenyl, biphenyl, biphenyl, terphenyl, quaterphenyl, quinquephenyl, triphenyl, fluorenyl, spirobifluorenyl, dihydophenanthryl, dihydropyrenyl, tetrahydropyrenyl, cis- or trans-indenofluorenyl, cis- or trans-monobenzoindenofluorenyl, cis- or trans-dibenzoindenofluorenyl, triindenyl, isotriindenyl, spirotrindenyl, spiroisotriindenyl, furanyl, benzofuranyl, isobenzofuranyl, dibenzofuranyl, thienyl, benzothienyl, isobenzothienyl, dibenzothienyl, pyrrolyl, indolyl, isoindolyl, carbazolyl, indolocarbazolyl, indenocarbazolyl, pyridyl, quinolyl, isoquinolyl, acridinyl, phenanthridinyl, benzo-5,6-quinolyl, benzo-6,7-quinolyl, benzo-7,8-quinolyl, phenoxazinyl, phenoxazinyl, pyrazolyl, indazolyl, imidazolyl, benzimidazolyl, naphthimidazolyl, phenanthroimidazolyl, pyridimidazolyl, pyrazimidazolyl, quinoximidazolyl, oxazolyl, benzoxazolyl, naphthoxazolyl, anthroxazolyl, phenanthroxazolyl, isoxazolyl, 1,2-thiazolyl, 1,3-thiazolyl, benzothiazolyl, pyridazinyl, benzopyridazinyl, pyrimidinyl, benzopyrimidinyl, quinoxalinyl, 1,5-diazanthrenyl, 2,7-diazapyrenyl, 2,3-diazapyrenyl, 1,6-diazapyrenyl, 1,8-diazapyrenyl, 4,5-diazapyrenyl, 4,5,9,10-tetraazaperylenyl, pyrazinyl, phenoxazinyl, phenoxazinyl, phenothiazinyl, fluorubinyl, naphthidinyl, azacarbazolyl, benzocarbolinyl, phenanthrolinyl, 1,2,3-triazolyl, 1,2,4-triazolyl, benzotriazolyl, 1,2,3-oxadiazolyl, 1,2,4-oxadiazolyl, 1,2,5-oxadiazolyl, 1,3,4-oxadiazolyl, 1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl, 1,3,4-thiadiazolyl, 1,3,5-triazinyl, 1,2,4-triazinyl, 1,2,3-triazinyl, tetrazolyl, 1,2,4,5-tetrazinyl, 1,2,3,4-tetrazinyl, 1,2,3,5-tetrazinyl, purinyl, pteridinyl, indolizinyl, benzothiadiazolyl.

[0016] Further, the 2,4-diazafluorene derivative represented by the general formula (I) is selected from the group consisting of the following compounds:

[0017]

[0018] Further, the 2,4-diazafluorene derivative represented by the general formula (I) is selected from the group consisting of the following compounds:

[0019]

[0020] Further, the 2,4-diazafluorene derivative represented by the general formula (I) is selected from the following compounds:

[0021]

[0022] Further, the 2,4-diazafluorene derivative represented by the general formula (I) is selected from the following compounds:

[0023]

[0024] The second object of the present application is to provide an electronic device using the aforementioned 2,4-diazafluorene derivative as a material for a functional layer.

[0025] Further, the electronic device is an organic electroluminescent device; wherein the organic electroluminescent device comprises a first electrode, a second electrode provided opposite to the first electrode, and at least one organic layer sandwiched between the first electrode and the second electrode.

[0026] The third object of the present application is to provide an electron transport layer material comprising the organic compound according to the first object.

[0027] The fourth object of the present application is to provide a hole blocking layer material comprising the organic compound according to the first object.

[0028] The fifth object of the present application is to provide a light emitting layer host material comprising the organic compound according to the first object.

[0029] Effects of the invention

[0030] The 2,4-diazafluorene derivative compound of the present application has a special D-π-A parent nucleus structure, has high thermal stability, chemical stability and carrier transport property, and more importantly, has suitable singlet, triplet and molecular orbital energy levels, is easy to control the HOMO / LUMO energy level of the compound and balance the glass transition temperature by reasonable material design. Therefore, when it is introduced into a molecule with electroluminescent properties, it is beneficial to improve the stability and light-emitting efficiency of the device, and reduce the driving voltage of the device.

[0031] The 2,4-diazafluorene derivative of the present application has good film-forming property and thermal stability by introducing a 2,4-diazafluorene derivative parent nucleus structure, and can be used for preparing an organic electroluminescent device, especially as a constituent material of a light-emitting layer, a hole-blocking layer or an electron-transporting layer in the organic electroluminescent device, and can exhibit the advantages of high light-emitting efficiency, long service life and low driving voltage, which are significantly superior to those of the prior art organic electroluminescent device.

[0032] In addition, the 2,4-diazafluorene derivative of the present application has a simple preparation method and readily available raw materials, and can meet the development needs of industrialization.

[0033] The 2,4-diazafluorene derivative of the present application has good application effect in electronic devices such as organic electroluminescent devices, and has wide industrialization prospects.

[0034] The 2,4-diazafluorene derivative of the present application has excellent hole-blocking ability, excellent electron-transporting performance, and is stable in a thin film state. Therefore, the organic electroluminescent device having a hole-blocking layer prepared using the 2,4-diazafluorene derivative of the present application has high light-emitting efficiency, low driving voltage, and improved current resistance, so that the maximum light-emitting brightness of the organic electroluminescent device is increased.

[0035] The 2,4-diazafluorene derivative of the present application can be used as a constituent material of a light-emitting layer, a hole-blocking layer or an electron-transporting layer of an organic electroluminescent device. Using the organic electroluminescent device of the present application, the excitons generated in the light-emitting layer can be limited, and the possibility of recombination of holes and electrons can be further increased to obtain high light-emitting efficiency. In addition, the driving voltage is so low that high durability can be achieved. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is the fluorescence spectrum (PL) of Example 1 (compound 1-2) in dichloromethane solution;

[0037] Figure 2 is a structural diagram of an example organic electroluminescent device.

[0038] Legend of the figures

[0039] 1-substrate, 2-anode, 3-hole injection layer, 4-hole transport layer, 5-electron blocking layer, 6-light-emitting layer, 7-hole blocking layer, 8-electron transport layer, 9-electron injection layer, 10-cathode. DETAILED DESCRIPTION

[0040] Hereinafter, the embodiments of the present application will be described in detail. However, the present application is not limited by the following embodiments.

[0041] <Manufacturing method>

[0042] The 2,4-diazafluorene derivative of the present application, for example, can be synthesized by the following method:

[0043] Examples

[0044] The manufacture of the compound represented by the above general formula (I) and the organic electroluminescent device comprising the same is specifically described in the following examples. However, the following examples are only for exemplifying the present application, and the scope of the present application is not limited thereto.

[0045] Example 1: Synthesis of compound 1-2

[0046] The synthetic route of intermediate M1 is shown below:

[0047]

[0048] In a 50 mL single-necked flask, 1-indanone (2.64 g, 20 mmol) and N,N-dimethylformamide dimethyl acetal (5 mL, 37.6 mmol) were added, and the system was refluxed for 6 hours. After the reaction was completed, it was cooled, and the solid was collected by suction filtration, and the solid was washed with a small amount of petroleum ether to obtain 3.52 g of an orange-red solid with a yield of 94%. The crude product was directly used in the next step without further purification. MS (EI): m / z: 187.14 [M + ] Anal. calcd for C 12 H 13 NO (%): C 76.98, H 7.00, N 7.48; found: C 76.96, H 7.02, N 7.46.

[0049] In a dry and clean 100 mL single-necked flask, sodium methoxide (2.03 g, 37.6 mmol), 4-bromophenylformamidine hydrochloride (8.87 g, 37.6 mmol), and 50 mL of anhydrous ethanol were sequentially added. While stirring, 20 mL of an anhydrous ethanol solution of the product (3.52 g, 18.8 mmol) from the previous step was added dropwise, and after the dropwise addition was completed, the system was refluxed for 3 hours. After the reaction was completed, it was cooled to room temperature, and inorganic salts were removed by suction filtration, and the filter cake was washed with a small amount of anhydrous ethanol. The filtrate was poured into 200 mL of water, neutralized with 1N hydrochloric acid, and extracted with dichloromethane. The filtrate was dried and concentrated to obtain a purple solid, and the crude product was recrystallized (decolorized with activated carbon) with ethanol to obtain 3.34 g of a white solid with a yield of 55%. MS (EI): m / z: 323.10 [M + ] Anal. calcd for C 17 H 11BrN2 (%): C 63.18, H3.43, N 8.67; found: C 63.16, H 3.44, N 8.66.

[0050] The synthetic route for intermediate M2 is shown below:

[0051]

[0052] Intermediate M1 (3.23 g, 10 mmol) was transferred to a 250 mL three-necked flask equipped with a dropping funnel. Under nitrogen protection, 100 mL of tetrahydrofuran was added, stirred to dissolve, and cooled in an ice-water bath. Sodium tert-butoxide (4.0 g, 41.7 mmol) was added in the ice bath, and the mixture was stirred for 10 min while maintaining the temperature. Then, methyl iodoform (5.9 g, 41.7 mmol) was added. The system was stirred for another 30 min, then the ice bath was removed, and the system was allowed to warm to room temperature. The reaction was continued overnight at room temperature. After the reaction was complete, insoluble matter was removed by filtration. The filtrate was concentrated and purified by column chromatography (petroleum ether:dichloromethane = 3:1 (V / V)) to give 2.67 g of white solid, yield 76%. MS (EI): m / z: 351.02 [M] + Anal.calcd for C 19 H 15 BrN2 (%): C 64.97, H4.30, N 7.98; found: C 64.93, H 4.35; N 7.97.

[0053] The synthetic routes for compounds 1-2 are shown below:

[0054]

[0055] Under nitrogen protection, intermediate M2 (1.76 g, 5 mmol), 3,9′-bicarbazole (1.7 g, 5.2 mmol), palladium acetate (11 mg, 0.05 mmol), tri-tert-butylphosphine tetrafluoroborate (29 mg, 0.1 mmol), sodium tert-butoxide (960 mg, 10 mmol), and 120 mL of toluene were added sequentially to a 250 mL Schlenk flask, and the mixture was refluxed and stirred for 12 hours. After the reaction was complete, the solvent was evaporated, the residue was dissolved in 200 mL of dichloromethane, washed with water, and the organic layer was separated. The aqueous layer was extracted twice with 15 mL of dichloromethane, and the organic layers were combined. After evaporation of the solvent, the residue was separated by column chromatography (petroleum ether:dichloromethane = 3:1 (V / V)). After evaporation of the solvent and drying, 2.3 g of white solid was given, with a yield of 76%. MS (EI): m / z: 602.22 [M + Anal.calcd for C 43 H 30N4(%) : C 85.69, H 5.02, N 9.30; found: C 85.59, H 4.98, N 9.28.

[0056] Example 2: Synthesis of compound 2-3

[0057] The synthetic route of compound 2-3 is shown below:

[0058]

[0059] In a 250 mL Schlenk flask, intermediate M2 (1.76 g, 5 mmol), 5,7-dihydro-5-phenylindolo[2,3-B]carbazole (1.7 g, 5.2 mmol), palladium acetate (11 mg, 0.05 mmol), tri-tert-butylphosphine tetrafluoroborate (29 mg, 0.1 mmol), sodium tert-butoxide (960 mg, 10 mmol) and 120 mL of toluene were added successively under nitrogen protection, and the reaction was stirred at reflux for 12 hours. After the reaction was completed, the solvent was evaporated, the residue was dissolved in 200 mL of dichloromethane, washed with water, and the organic layer was separated. The water layer was extracted with 15 mL of dichloromethane twice, and the organic layers were combined. After the solvent was evaporated, the residue was separated by column chromatography (petroleum ether: dichloromethane = 3: 1 (V / V)). After the solvent was evaporated and dried, 1.9 g of white solid was obtained, with a yield of 63%. MS (EI): m / z: 602.32 [M + ] Anal. calcd for C 43 H 30 N4(%) : C 85.69, H 5.02, N 9.30; found: C 85.59, H 4.98, N 9.28.

[0060] Example 3: Synthesis of compound 3-3

[0061] The synthetic route of compound 3-3 is shown below:

[0062]

[0063] A 250 mL Schlenk flask was charged with intermediate M2 (1.76 g, 5 mmol), 5,7- dihydro-7,7-dimethyl-indeno[2,l-B]carbazole (1.5 g, 5.2 mmol), palladium acetate (11 mg, 0.05 mmol), tri-tert-butylphosphonium tetrafluoroborate (29 mg, 0.1 mmol), sodium tert-butoxide (960 mg, 10 mmol) and 120 mL of toluene under nitrogen. The reaction was stirred at reflux for 12 h. After the reaction was completed, the solvent was evaporated, the residue was dissolved in 200 mL of dichloromethane, washed with water, the organic layer was separated, and the aqueous layer was extracted with 15 mL of dichloromethane twice, and the organic layers were combined. After the solvent was evaporated, the residue was separated by column chromatography (petroleum ether:dichloromethane = 3: 1 (V / V)). After the solvent was evaporated and dried, 2.0 g of white solid was obtained with a yield of 72%. MS (EI): m / z: 553.35 [M+H]+. Anal. calcd for C39H30N2(%) : C 91.82, H 5.46, N 2.72; found: C 91.80, H 5.45, N 2.70. + ]Anal. calcd for C 40 H 31 N3(%) : C 86.77, H 5.64, N 7.59; found: C 86.70, H 5.60, N 7.56.

[0064] Example 4: Synthesis of compound 4-1

[0065] The synthetic route of compound 4-1 is shown below:

[0066]

[0067] A 250 mL Schlenk flask was charged with intermediate M2 (1.76 g, 5 mmol), 5,7- dihydro-7,7-dimethyl-indeno[2,l-B]carbazole (1.5 g, 5.2 mmol), palladium acetate (11 mg, 0.05 mmol), tri-tert-butylphosphonium tetrafluoroborate (29 mg, 0.1 mmol), sodium tert-butoxide (960 mg, 10 mmol) and 120 mL of toluene under nitrogen. The reaction was stirred at reflux for 12 h. After the reaction was completed, the solvent was evaporated, the residue was dissolved in 200 mL of dichloromethane, washed with water, the organic layer was separated, and the aqueous layer was extracted with 15 mL of dichloromethane twice, and the organic layers were combined. After the solvent was evaporated, the residue was separated by column chromatography (petroleum ether:dichloromethane = 3: 1 (V / V)). After the solvent was evaporated and dried, 2.0 g of white solid was obtained with a yield of 72%. MS (EI): m / z: 553.35 [M+H]+. Anal. calcd for C39H30N2(%) : C 91.82, H 5.46, N 2.72; found: C 91.80, H 5.45, N 2.70. + ]Anal. calcd for C 37 H 25 N3O(%) : C 84.23, H 4.78, N 7.96; found: C 84.20, H 4.75, N 7.92.

[0068] <Organic electroluminescent device>

[0069] Example 5: Preparation of Organic Electroluminescent Device 1 (Organic EL Device 1)

[0070] A hole injection layer 3, a hole transport layer 4, an electron blocking layer 5, a light emitting layer 6, a hole blocking layer 7, an electron transport layer 8, an electron injection layer 9, and a cathode 10 were sequentially formed on the transparent anode 2 previously formed on the glass substrate 1 to prepare an organic electroluminescent device as shown in FIG. 1. Figure 2

[0071] Specifically, a glass substrate on which an ITO film having a thickness of 100 nm was formed was subjected to ultrasonic treatment in a Decon 90 alkaline cleaning solution, rinsing in deionized water, cleaning in acetone and ethanol each three times, baking in a clean environment to completely remove moisture, cleaning with ultraviolet light and ozone, and surface bombardment with a low-energy cation beam. The glass substrate with the ITO electrode was placed in a vacuum chamber, and vacuumed to 4 x 10 -4 -2 x 10 -5 Pa. Then, 2,3,6,7,10,11-hexacyano-l,4,5,8,9,12-hexaazatriphenylene (HAT-CN) was evaporated at a rate of 0.2 nm / s on the glass substrate with the ITO electrode to form a layer having a thickness of 10 nm as a hole injection layer. N,N'-diphenyl-N,N'-(l-naphthyl)-l,l'-biphenyl-4,4'-diamine (NPB) was evaporated at a rate of 0.2 nm / s on the hole injection layer to form a layer having a thickness of 40 nm as a hole transport layer. 3,3'-di(N-carbazolyl)-l,l'-biphenyl (mCBP) was evaporated at a rate of 0.2 nm / s on the hole transport layer to form a layer having a thickness of 10 nm as an electron blocking layer (EBL). Compound 7 of Example 1 as a host material was co-evaporated at a rate of 0.2 nm / s and GDl as a dopant material was co-evaporated at a rate of 0.16 nm / s on the electron blocking layer to form a layer having a thickness of 20 nm as a light emitting layer, and the doping weight ratio of GDl was 8 wt%. Aluminum (III) bis(2-methyl-8-quinolinate)-4-phenylphenolate (BAlq) was evaporated at a rate of 0.2 nm / s on the light emitting layer to form a layer having a thickness of 10 nm as a hole blocking layer (HBL). BAlq was evaporated at a rate of 0.2 nm / s on the hole blocking layer to form a layer having a thickness of 40 nm as an electron transport layer (ETL). 8-hydroxyquinoline-lithium (Liq) was evaporated at a rate of 0.1 nm / s on the electron transport layer to form a layer having a thickness of 2 nm as an electron injection layer. Finally, aluminum was evaporated at a rate of 0.5 nm / s or more to form a cathode having a thickness of 100 nm. ​

[0072] The organic electroluminescent device of the present application includes a first electrode, a second electrode provided opposite to the first electrode, and at least one organic layer sandwiched between the first electrode and the second electrode, wherein the at least one organic layer contains the 2,4-diazafluorene derivative of the present application.

[0073] In the organic electroluminescent device of the present application, for example, an anode 2, a hole injection layer 3, a hole transport layer 4, an electron blocking layer 5, a light emitting layer 6, a hole blocking layer 7, an electron transport layer 8, an electron injection layer 9, and a cathode 10 are sequentially provided on a substrate 1. The organic electroluminescent device of the present application is not limited to such a structure, and for example, some of the organic layers can be omitted in the multilayer structure.

[0074] As the electron blocking layer of the organic electroluminescent device of the present application, a publicly known compound having an electron blocking action is preferably used. For example, there can be mentioned: carbazole derivatives such as 4,4',4"-tris(N-carbazolyl)triphenylamine (TCTA), 9,9-bis[4-(carbazol-9-yl)phenyl]fluorene, 1,3-bis(carbazol-9-yl)benzene (mCP), 2,2-bis(4-carbazol-9-ylphenyl)adamantane (Ad-Cz), and the like; a compound having a triphenylsilyl group and a triarylamine structure represented by 9-[4-(carbazol-9-yl)phenyl]-9-[4-(triphenylsilyl)phenyl]-9H-fluorene; a monoamine compound having a high electron blocking property; various triphenylamine dimers; and the like having an electron blocking action.

[0075] As the light emitting layer of the organic electroluminescent device of the present application, the 2,4-diazafluorene derivative of the present application is preferably used. The light emitting layer can be composed of a host material and a dopant material. As the host material, the 2,4-diazafluorene derivative of the present application is preferably used.

[0076] As the hole blocking layer of the organic electroluminescent device of the present application, the 2,4-diazafluorene derivative of the present application is preferably used. In addition thereto, other compounds having a hole blocking property can also be used for formation. For example, there can be used 2,4,6-tris(3-phenyl)-1,3,5-triazine (T2T), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), bathocuproin (BCP), a metal complex of a quinolinol derivative such as bathocuproin (BCP), aluminum(III)bis(2-methyl-8-hydroxyquinoline)-4-phenylphenolate (BAlq), and the like, and various rare earth complexes, oxazole derivatives, triazole derivatives, triazine derivatives, and the like having a hole blocking action.

[0077] As the electron transport layer of the organic electroluminescent device of the present application, it is preferable to use the 2,4-diazafluorene derivative of the present application. In addition to this, other compounds having electron transport properties can also be used. For example, metal complexes of hydroxyquinoline derivatives such as Alq3, BAlq; various metal complexes; triazole derivatives; triazine derivatives; and the like can be used.

[0078] <Material performance characterization>

[0079]

[0080] The 2,4-diazafluorene derivative of the present application has excellent luminous efficiency and lifetime characteristics, and low driving voltage. Therefore, an organic electroluminescent device having an excellent service life can be produced from this compound.

[0081] The present application is illustrated by the above examples, but the present application is not limited to the above examples, i.e. it is not meant that the present application must be practiced depending on the above examples. It should be apparent to those skilled in the art that any improvement on the present application, equivalent replacement of each material of the product of the present application, addition of auxiliary ingredients, selection of specific modes, etc. fall within the scope of protection and disclosure of the present application.

Claims

1. A 2,4-diazafluorene derivative, characterized in that, The 2,4-diazafluorene derivatives are selected from the following compounds: 。 2. An electronic device, characterized in that, It includes the 2,4-diazafluorene derivative as described in claim 1.

3. The electronic device according to claim 2, characterized in that, The electronic device is an organic electroluminescent device; The organic electroluminescent device includes: a first electrode, a second electrode disposed opposite to the first electrode, and at least one organic layer sandwiched between the first electrode and the second electrode, wherein the at least one organic layer comprises the 2,4-diazafluorene derivative as described in claim 1.

4. The electronic device according to claim 3, characterized in that, The at least one organic layer is a light-emitting layer.

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