A luminescent compound, its preparation and use

Abstract

The application belongs to the technical field of organic photoelectric materials, and discloses a luminescent compound and a preparation method and application thereof. The luminescent compound takes anthracene or a derivative of anthracene as a core structure, introduces an indole and carbazole group and a group containing an aromatic ring structure for structural modification, and after the structural modification, the spatial steric hindrance and the charge transfer degree of the molecule can be adjusted, and then the emission spectrum and the molecular aggregation form are adjusted, so that the purpose of improving the reverse intersystem crossing from the triplet exciton to the singlet state is achieved. The compound is a blue fluorescent compound, has high luminous efficiency, and the high luminous efficiency indicates that the compound can be used as a luminescent material or a luminescent host material, especially as a fluorescent host material, and is used in an organic electroluminescent device to exhibit high efficiency, high brightness, long service life and better charge transport capacity, has the advantages of low manufacturing cost, prolongs the service life of the organic electroluminescent device and reduces the manufacturing cost of the organic electroluminescent device.

Description

Technical Field

[0001] This invention belongs to the field of organic optoelectronic materials technology, and specifically relates to a luminescent compound, its preparation method, and its application. Background Technology

[0002] Organic light-emitting diodes (OLEDs) possess advantages such as active light emission, low driving voltage, fast response speed, and the ability to achieve flexible displays, and have been widely used globally after more than 30 years of development. Among these, luminescent materials are the core of OLED display technology and possess high technological barriers. Currently, research on red and green light materials is relatively mature, while research on blue / deep blue light materials lags behind. High-performance blue light materials, especially deep blue light materials, are not only beneficial for achieving a wider color gamut but also effectively reduce the power consumption of display and lighting devices, making them key materials in this field. However, due to their wide bandgap, the design and development of high-efficiency blue light materials are constrained by problems such as unbalanced carrier injection and transport, and the difficulty in simultaneously achieving high light color and high device efficiency, which has become a challenge for the development of the OLED field.

[0003] The core of breakthroughs in OLED material efficiency lies in the utilization of triplet excitons. Limited by spin statistics, 75% of the excited states in traditional OLEDs are non-luminescent triplet states. Devices utilizing only singlet excitons have low efficiency, with an EQE limited to 5%. Phosphorescent materials utilize the spin-orbit coupling effect of noble metals to transform non-luminescent triplet states into luminescent excited states, and have become the main material system used in current OLED production lines. Following phosphorescent materials, to reduce costs, international research has proposed using pure organic fluorescent molecules to improve exciton utilization and obtain inexpensive, high-efficiency materials. Examples include triplet-triplet annihilation (TTA), thermally activated delayed fluorescence (TADF), and the thermal exciton principle. The thermal exciton mechanism emphasizes the presence of high-energy exciton conversion channels in molecular excited states and proposes using the weak binding energy of high-energy CT state excitons to achieve the RISC process, while the low-energy locally excited (LE) radiative transitions remain unaffected, thus achieving separation of exciton radiation and exciton conversion. This design avoids the redshift caused by the formation of strong intramolecular charge-transfer states (CT), thus offering a natural advantage in the chromaticity modulation of blue light molecules. Furthermore, the rapid reverse intersystem crossing speed of high-energy triplet excitons prevents efficiency roll-off due to accumulation at high current densities. Simultaneously, this design strategy enables high electroluminescence efficiency even in undoped devices and simplifies device fabrication processes, thereby reducing costs. Summary of the Invention

[0004] To overcome the shortcomings and deficiencies of the prior art, the primary objective of this invention is to provide a luminescent compound. It uses anthracene or anthracene derivatives as its core structure, and modifies its structure by introducing indole-carbazole groups and groups containing aromatic ring conjugated structures. This allows for the regulation of high-energy excited-state properties, achieving exciton utilization primarily through a thermal exciton mechanism, thereby obtaining a highly efficient exciton utilization rate.

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned luminescent compound.

[0006] Another object of the present invention is to provide the application of the above-mentioned luminescent compounds in light-emitting diode devices and / or organic electroluminescent devices.

[0007] Another object of the present invention is to provide an organic electroluminescent device.

[0008] The objective of this invention is achieved through the following solution:

[0009] A luminescent compound having an anthracene or an anthracene derivative as its core structure, and modified by introducing an indolocarbazole group and a group containing an aromatic ring structure.

[0010] As a further preferred embodiment, in this application, the luminescent compound has one of the following structural formula (Ⅰ) or a derivative of the following structural formula (Ⅰ):

[0011]

[0012] Where Ar is C6-C 60 Aromatic ring groups or derivative groups of aromatic rings, wherein C6-C 60 The aromatic ring derivative group is C6-C. 60 Halogenated aromatic ring groups, C6-C 60 Alkyl-substituted products of aromatic ring groups, C6-C 60 Alkoxy-substituted products of aromatic ring groups, C6-C 60 One of the cyano-substituted derivatives of the aromatic ring group.

[0013] As a further preferred embodiment, in this application, Ar is one of the following structural formulas or derivatives of the following structural formulas with substituents on the benzene ring:

[0014]

[0015] The substituents in the derivatives with substituents on the benzene ring of the structural formula are halogens or C1-C. 20 Alkyl groups, halogens including Cl, Br, the C1-C 20The alkyl group includes straight-chain alkyl or branched alkyl; preferably, the alkyl group is a C1-C8 straight-chain alkyl group. The substituent can replace any substituted position on the benzene ring, and can be one or more substituents, each of which is independent of each other.

[0016] As a further preferred embodiment, the chemical structural formula of the luminescent compound is one of the following structural formulas:

[0017]

[0018] A method for preparing the above-mentioned luminescent compound includes the following steps:

[0019] (1) Ar-Br was reacted with pinacol diboronic acid ester to generate compound I;

[0020] (2) 2-bromoindolo[3,2,1-JK]carbazole and 2,6-dibromoanthraquinone were reacted in a solvent with n-butyllithium, and then stannous chloride dihydrate was added to give compound II.

[0021] (3) Reacting compound I and compound II yields the luminescent compound shown in formula (I);

[0022] The specific reaction route is shown below:

[0023]

[0024] The reaction described in step (1) is preferably carried out in a solvent in the presence of a catalyst and a base, wherein the solvent is preferably 1,4-dioxane, the catalyst is preferably [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride, and the base is preferably potassium acetate; the reaction is carried out at 60-110℃ for 8-12 hours.

[0025] The addition of n-butyllithium in step (2) refers to adding n-butyllithium at -78°C and stirring for 8-12 hours; the addition of stannous chloride dihydrate refers to reacting at -78°C to 0°C for 8-12 hours.

[0026] The reaction in step (3) refers to the reaction occurring in a solvent in the presence of a catalyst and a base. The solvent is preferably toluene, the catalyst is preferably tetra(triphenylphosphine)palladium and tetrabutylammonium bromide, and the base is preferably potassium carbonate. The reaction is preferably carried out at 90-110°C for 8-12 hours.

[0027] This application also discloses an anthracene-based blue fluorescent compound, wherein the anthracene-based blue fluorescent small molecule is a small molecule having the above-described luminescent compound structure or a small molecule containing a fragment of the luminescent compound structure.

[0028] The anthracene-based blue fluorescent small molecule described in this application is used in light-emitting diode devices and / or organic electroluminescent devices to fabricate light-emitting devices or light-emitting layers.

[0029] An organic electroluminescent device comprises, from bottom to top, an anode, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode; wherein the organic light-emitting layer is the aforementioned anthracene-based blue fluorescent molecule or contains the aforementioned anthracene-based blue fluorescent molecule.

[0030] As a further preferred embodiment, in this application, the organic light-emitting layer is a pure film of blue fluorescent molecules or a composite film doped with a guest. The guest is preferably 4,4'-bis[4-(di-p-tolylamino)styryl]biphenyl (DPAVBi), with a mass fraction of 1%-20%.

[0031] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0032] 1. The luminescent compound described in this application uses an anthracene core as the building unit. By introducing indole-carbazole groups and aromatic ring groups for structural modification, its high-energy excited state properties can be regulated, which can open the high-energy reverse intersystem crossing channel of excitons, realize the "thermal exciton" mechanism, and achieve 100% utilization of excitons.

[0033] 2. This application provides an anthracene-containing compound, its preparation method, and its application. The anthracene-containing compound has high luminous efficiency, which indicates that the compound can be used as a luminescent material or a luminescent host material, especially as a fluorescent host material. When used in organic electroluminescent devices, it exhibits high efficiency, high brightness, long lifespan, and better charge transport capability. It also has the advantage of low manufacturing cost, extends the lifespan of organic electroluminescent devices, and reduces the manufacturing cost of organic electroluminescent devices.

[0034] 3. The luminescent compounds described in this application adjust the steric hindrance and charge transfer of molecules by selecting Ar groups and using heterocyclic compounds with aromatic rings or aryl groups, thereby adjusting the emission spectrum and molecular aggregation form, and thus improving the antisystem crossing from triplet excitons to singlet states. Attached Figure Description

[0035] Figure 1 The image shows the UV-Vis absorption spectra of luminescent compounds M1-M4 in toluene solution.

[0036] Figure 2 The fluorescence emission spectra of luminescent compounds M1-M4 in toluene solution are shown.

[0037] Figure 3 Thermogravimetric analysis diagrams of luminescent compounds M1-M4.

[0038] Figure 4 The electroluminescence spectra of undoped organic electroluminescent devices based on luminescent compounds M1-M4 are shown. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0040] The term "comprising" and other equivalent descriptive terms used in the specification and claims of this application are intended to cover a non-exclusive inclusion, which includes both the contents explicitly described in the specification and claims and steps or units that are not described in the specification and claims but are inherent in the product, method or structure.

[0041] This application discloses a luminescent compound with an anthracene derivative as its core structure. The compound is modified by introducing indolocarbazole and groups containing aromatic ring conjugated structures to regulate the properties of high-energy excited states, achieving exciton utilization primarily through a thermal exciton mechanism, thereby improving exciton utilization efficiency. In this embodiment, the use of aromatic ring structures for modification can adjust the steric hindrance and charge transfer degree of the molecule, thereby regulating the emission spectrum and molecular aggregation form, ultimately enhancing the antisystem crossing from triplet excitons to singlet excitons.

[0042] Example 1

[0043] This embodiment provides a luminescent compound M1, whose molecular formula is C1. 64 H 40 N2O2, structural formula:

[0044]

[0045] The synthetic route and method for the luminescent compound are as follows:

[0046]

[0047] (1) Synthesis of Compound 1

[0048] Under a nitrogen atmosphere, 4-bromoanisole (30.00 mmol) and pinacol diborate (60.00 mmol) were added to a 250 mL double-necked flask and stirred with 100 mL of 1,4-dioxane until completely dissolved. Then, [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride (2.00 mmol) and potassium acetate (90.00 mmol) were added, and the mixture was heated to 90 °C and stirred for 12 hours. Post-treatment: (1) Extraction with dichloromethane and water; (2) Vacuum rotary evaporation to obtain the crude product; (3) Column chromatography separation of the product using petroleum ether and dichloromethane as eluents to obtain compound 1. 1 HNMR, 13 CNMR, MS and elemental analysis results indicate that the obtained compound is the target product.

[0049] (2) Synthesis of compound 2

[0050] Under a nitrogen atmosphere, 2-bromoindolo[3,2,1-JK]carbazole (70.00 mmol) and 2,6-dibromoanthraquinone (30.00 mmol) were added to a 250 mL double-necked flask and stirred with 100 mL of tetrahydrofuran until completely dissolved. The mixture was cooled to -78 °C, and n-butyllithium (60.00 mmol) was slowly added. The mixture was stirred for 12 hours, and then stannous chloride dihydrate (60.00 mmol) was added. The mixture was stirred for another 12 hours and then quenched with water. Post-treatment: (1) Extraction with dichloromethane; (2) Vacuum rotary evaporation to obtain the crude product; (3) Column chromatography separation of the product using petroleum ether and dichloromethane as eluents to obtain compound 2. 1 HNMR, 13 CNMR, MS and elemental analysis results indicate that the obtained compound is the target product.

[0051] (3) Synthesis of compound M1

[0052] Under a nitrogen atmosphere, compound 1 (40.00 mmol), compound 2 (20.00 mmol), tetra(triphenylphosphine)palladium (1.00 mmol), tetrabutylammonium bromide (2.00 mmol), and potassium carbonate (50 mmol) were placed in a 250 mL round-bottom flask. Then, 150 mL of toluene was added, and the mixture was stirred and heated to 90 °C for 12 hours. When the reaction cooled to room temperature, the following post-treatments were performed: (1) extraction with dichloromethane and water; (2) rotary evaporation under vacuum to obtain the crude product; (3) column chromatography using petroleum ether and dichloromethane as eluents to separate the product and obtain compound M1. 1 HNMR, 13 CNMR, MS and elemental analysis results indicate that the obtained compound is the target product.

[0053] Example 2

[0054] This embodiment provides a luminescent compound M2 with the molecular formula C. 86 H 50 N4, the structural formula is:

[0055]

[0056] The synthetic route and method for the luminescent compound are as follows:

[0057]

[0058] (1) Synthesis of compound 3

[0059] Under a nitrogen atmosphere, 9-(4-bromophenyl)carbazole (30.00 mmol) and pinacol diboronate (60.00 mmol) were added to a 250 mL double-necked flask and stirred with 100 mL of 1,4-dioxane until completely dissolved. Then, [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride (2.00 mmol) and potassium acetate (90.00 mmol) were added, and the mixture was heated to 90 °C and stirred for 12 hours. Post-treatment: (1) Extraction with dichloromethane and water; (2) Vacuum rotary evaporation to obtain the crude product; (3) Column chromatography separation of the product using petroleum ether and dichloromethane as eluents to obtain compound 3. 1 HNMR, 13 CNMR, MS and elemental analysis results indicate that the obtained compound is the target product.

[0060] (2) Synthesis of compound M2

[0061] Under a nitrogen atmosphere, compound 3 (40.00 mmol), compound 2 (20.00 mmol), tetra(triphenylphosphine)palladium (1.00 mmol), tetrabutylammonium bromide (2.00 mmol), and potassium carbonate (50 mmol) were placed in a 250 mL round-bottom flask. Then, 150 mL of toluene was added, and the mixture was stirred and heated to 90 °C for 12 hours. When the reaction cooled to room temperature, the following post-treatments were performed: (1) extraction with dichloromethane and water; (2) rotary evaporation under vacuum to obtain the crude product; (3) column chromatography using petroleum ether and dichloromethane as eluents to separate the product and obtain compound M2. 1 HNMR, 13 CNMR, MS and elemental analysis results indicate that the obtained compound is the target product.

[0062] Example 3

[0063] This embodiment provides a luminescent compound M3 with the molecular formula C3. 62 H 34 F2N2, the structural formula is:

[0064]

[0065] The specific synthetic route and preparation method steps are as follows:

[0066]

[0067] (1) Synthesis of compound 4

[0068] Under a nitrogen atmosphere, 4-bromofluorobenzene (30.00 mmol) and pinacol diboronate (60.00 mmol) were added to a 250 mL double-necked flask and stirred with 100 mL of 1,4-dioxane until completely dissolved. Then, [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride (2.00 mmol) and potassium acetate (90.00 mmol) were added, and the mixture was heated to 90 °C and stirred for 12 hours. Post-treatment: (1) Extraction with dichloromethane and water; (2) Vacuum rotary evaporation to obtain the crude product; (3) Column chromatography using petroleum ether and dichloromethane as eluents to separate the product, yielding compound 4. 1 HNMR, 13 CNMR, MS and elemental analysis results indicate that the obtained compound is the target product.

[0069] (2) Synthesis of compound M3

[0070] Under a nitrogen atmosphere, compound 4 (40.00 mmol), compound 2 (20.00 mmol), tetra(triphenylphosphine)palladium (1.00 mmol), tetrabutylammonium bromide (2.00 mmol), and potassium carbonate (50 mmol) were placed in a 250 mL round-bottom flask. Then, 150 mL of toluene was added, and the mixture was stirred and heated to 90 °C for 12 hours. When the reaction cooled to room temperature, the following post-treatments were performed: (1) extraction with dichloromethane and water; (2) rotary evaporation under vacuum to obtain the crude product; (3) column chromatography using petroleum ether and dichloromethane as eluents to separate the product and obtain compound M3. 1 HNMR, 13 CNMR, MS and elemental analysis results indicate that the obtained compound is the target product.

[0071] Example 4

[0072] This embodiment provides a luminescent compound M4 with the molecular formula C0. 70 H 52 N2, the structural formula is:

[0073]

[0074] The specific synthetic route and preparation method steps are as follows:

[0075]

[0076] (1) Synthesis of compound 5

[0077] Under a nitrogen atmosphere, 30.00 mmol of 4-tert-butylbromobenzene and 60.00 mmol of pinacol diborate were added to a 250 mL double-necked flask and stirred with 100 mL of 1,4-dioxane until completely dissolved. Then, 2.00 mmol of [1,1'-bis(diphenylphosphine)ferrocene]palladium dichloride and 90.00 mmol of potassium acetate were added, and the mixture was heated to 90 °C and stirred for 12 hours. Post-treatment: (1) Extraction with dichloromethane and water; (2) Vacuum rotary evaporation to obtain the crude product; (3) Column chromatography separation of the product using petroleum ether and dichloromethane as eluent to obtain compound 5. 1 HNMR, 13 CNMR, MS and elemental analysis results indicate that the obtained compound is the target product.

[0078] (2) Synthesis of compound M4

[0079] Under a nitrogen atmosphere, compound 5 (40.00 mmol), compound 2 (20.00 mmol), tetra(triphenylphosphine)palladium (1.00 mmol), tetrabutylammonium bromide (2.00 mmol), and potassium carbonate (50 mmol) were placed in a 250 mL round-bottom flask. Then, 150 mL of toluene was added, and the mixture was stirred and heated to 90 °C for 12 hours. When the reaction cooled to room temperature, the following post-treatments were performed: (1) extraction with dichloromethane and water; (2) rotary evaporation under vacuum to obtain the crude product; (3) column chromatography using petroleum ether and dichloromethane as eluents to separate the product and obtain compound M4. 1 HNMR, 13 CNMR, MS and elemental analysis results indicate that the obtained compound is the target product.

[0080] Application Example 1

[0081] This application example provides an undoped organic light-emitting diode device, which is prepared as follows: Take a pre-made indium tin oxide (ITO) glass with a sheet resistance of 15Ω, clean it sequentially with detergent, deionized water, isopropanol and detergent, and ultrasonically clean it, and then treat it with plasma for 15 minutes. Then, in a glove box, a 30 nm layer of polyethylene dioxythiophene-doped poly(styrene sulfonate) (PEDOT:PSS) is spin-coated onto the ITO surface as a hole injection layer. Next, in an evaporation machine, a 35 nm thick layer of 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA) is sequentially deposited as a hole transport layer, followed by 30 nm thick luminescent compounds M1–M4 as luminescent layers, a 25 nm thick layer of 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) as an electron transport layer, a 1 nm thick layer of lithium fluoride (LiF) as an electron injection layer, and a 100 nm thick layer of aluminum (Al) as a cathode. The device structure is: ITO / PEDOT:PSS / TCTA / luminescent layers (M1-M4) / TPBi / LiF / Al.

[0082] The performance parameters of the fabricated undoped organic light-emitting devices are shown in Table 1.

[0083] Table 1: Performance parameters of undoped organic light-emitting devices

[0084] Luminescent materials Start-up voltage (V) <![CDATA[Maximum brightness (cd m -2 )]]> <![CDATA[Maximum current efficiency (cd A -1 )]]> Color coordinates (x, y) M1 3.0 12000 8.2 (0.15,0.08) M2 3.2 12800 8.9 (0.14,0.07) M3 3.4 11700 7.9 (0.13,0.14) M4 3.9 12550 8.7 (0.13,0.09)

[0085] The results in the table show that all devices exhibit good color purity, with emission spectral peaks around 450 nm, demonstrating blue light emission. Furthermore, these devices all possess low turn-on voltages (<3.9V) and high brightness (>10000 cdm). -2 This indicates that the anthracene-based blue light-emitting small molecule provided by this invention can be used to construct a high-efficiency blue organic light-emitting diode.

[0086] Application Example 2

[0087] This application example provides a doped organic electroluminescent device, the preparation method of which is as follows: A pre-made indium tin oxide (ITO) glass with a sheet resistance of 15Ω is taken and sequentially ultrasonically cleaned with detergent, deionized water, isopropanol, and detergent, followed by plasma treatment for 15 minutes. Then, in a glove box, a 5nm thick layer of 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanodimethyl-p-benzoquinone (F4TCNQ) as a hole injection layer, a 35nm thick layer of 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA) as a hole transport layer, a 30nm thick layer of luminescent small molecules M1-M4 (98% by mass), and 4,4'-bis[4-(di-p-tolylamino)styryl]biphenyl (DPA) are deposited on the ITO surface. A mixed film of VBi (2% by mass) is used as the light-emitting layer, a 25 nm thick 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) is used as the electron transport layer, a 1 nm thick cesium fluoride (CsF) is used as the electron injection layer, and a 100 nm thick aluminum (Al) is used as the cathode. Device structure: ITO / F4TCNQ / TCTA / Light-emitting layer (M1-M4 (98%): DPAVBi (2%)) / TPBi / CsF / Al.

[0088] The performance results of the fabricated doped organic electroluminescent devices are shown in Table 2.

[0089] Table 2: Performance parameters of doped organic light-emitting devices

[0090] Luminescent materials Start-up voltage (V) <![CDATA[Maximum brightness (cd m -2 )]]> Maximum external quantum efficiency (%) Color coordinates (x, y) M1:BD 4.1 16680 10.3 (0.14,0.11) M2:BD 4.0 17580 12.3 (0.15,0.10) M3: BD 3.8 18700 13.8 (0.14,0.10) M4:BD 4.2 17880 14.5 (0.15,0.09)

[0091] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A luminescent compound, characterized in that... Its structure is as follows (Ⅰ): Equation (I) Where Ar is the following structural formula: 。 2. The luminescent compound according to claim 1, characterized in that... The chemical structural formula of the luminescent compound is one of the following: 。 3. An anthracene-based blue fluorescent compound, characterized in that... The anthracene-based blue fluorescent compound is the luminescent compound according to any one of claims 1-2.

4. A method for preparing a luminescent compound according to any one of claims 1-2, characterized in that... Includes the following steps: (1) Ar-Br reacts with pinacol diboronic acid ester to generate compound I; (2) 2-bromoindolo[3,2,1-JK]carbazole and 2,6-dibromoanthraquinone were reacted in a solvent with n-butyllithium, and then stannous chloride dihydrate was added to give compound II. (3) Reacting compound I and compound II yields the luminescent compound shown in formula (I); The specific reaction route is shown below: 。 5. The application of an anthracene-based blue fluorescent compound according to claim 3 in light-emitting diode devices or organic electroluminescent devices.

6. An organic electroluminescent device, characterized in that... From bottom to top, it includes an anode, a hole injection layer, a hole transport layer, an organic light-emitting layer, an electron transport layer, an electron injection layer, and a cathode; wherein the organic light-emitting layer is the anthracene-based blue fluorescent compound of claim 3 or a mixture containing the anthracene-based blue fluorescent compound of claim 3.

7. The organic electroluminescent device according to claim 6, characterized in that: The organic light-emitting layer is a pure film of the anthracene-based blue fluorescent compound as described in claim 3, or a composite film doped with a guest compound.

8. The organic electroluminescent device according to claim 7, characterized in that: The mass fraction of the guest in the composite film doped with the guest is 1%-20%.

9. The organic electroluminescent device according to claim 7, characterized in that: The guest in the composite film doped with the guest is 4,4'-bis[4-(di-p-tolylamino)styryl]biphenyl.

Images