A naphthocarbazole compound and application thereof

Abstract

The application provides a naphthocarbazole compound and application thereof, and relates to the technical field of organic photoelectric materials.The naphthocarbazole compound can be used as an electron transport layer material in an organic electroluminescent device, and can effectively reduce the driving voltage of the organic electroluminescent device, improve the current efficiency of the organic electroluminescent device, and improve the service life of the organic electroluminescent device.

Description

Technical Field

[0001] This invention belongs to the field of organic optoelectronic technology, specifically relating to a naphthocarbazole compound and its applications. Background Technology

[0002] Organic light-emitting diodes (OLEDs) have advantages such as light weight, small size, wide viewing angle, fast response, wide operating temperature range, low energy consumption, high efficiency, good color purity, high definition, and good flexibility. They can meet consumers' new demands for display technology and have a promising application prospect in the fields of lighting and display.

[0003] Organic light-emitting diodes (OLEDs) are self-emissive devices that utilize the principle that fluorescent materials emit light by recombination of holes injected from the anode and electrons injected from the cathode when an electric field is applied. They have the following structure: an anode, a cathode, and an organic material layer between them. To improve the efficiency and stability of OLEDs, the organic material layer typically comprises a multilayer structure with different materials, such as a hole injection layer (HIL), a hole transport layer (HTL), an emissive layer, an electron transport layer (ETL), and an electron injection layer (EIL). In such OLEDs, when a voltage is applied between the anode and cathode, holes from the anode and electrons from the cathode are injected into the organic material layer, and the resulting excitons migrate to the ground state, producing light with a specific wavelength.

[0004] Currently, research on organic electroluminescent materials has been widely carried out in academia and industry. Among these efforts, improving device lifetime and current efficiency while reducing driving voltage has consistently constrained the development of OLED devices. Therefore, designing and searching for a compound as a novel OLED material to overcome its shortcomings in practical applications is a key focus and future research trend in OLED materials. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a naphthocarbazole compound with excellent performance, suitable for use as an electron transport material in organic electroluminescent devices.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a naphthocarbazole compound having a structure as shown in Formula I:

[0008]

[0009] Among them, R1 to R3 are each independently selected from C1 to C2. 12Alkyl, substituted or unsubstituted C6-C 30 Aryl, substituted or unsubstituted C3-C 30 Any one of the heteroaryl groups;

[0010] The substituents are selected from C1 to C2. 12 Alkyl, C6-C 30 Aryl, C3~C 30 Any one of the heteroaryl groups;

[0011] Furthermore, the naphthocarbazole compounds do not include the following compounds:

[0012]

[0013] The naphthocarbazole compounds provided by this invention have specific molecular structures and spatial configurations, which endow them with excellent electron transport properties and film-forming properties, making the electron transport layer more compact, which is conducive to the transport of charge carriers, reducing the device driving voltage, promoting the improvement of device efficiency, extending the device's service life, and comprehensively improving the overall performance of organic electroluminescent devices.

[0014] Preferably, C1 to C 12 The alkyl group is selected from methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, p-pentyl, n-hexyl, or cyclohexyl.

[0015] Preferably, C6~C 30 The aryl group is selected from phenyl, biphenyl, terphenyl, naphthyl, anthracene, indyl, fluorenyl, perylene, phenanthryl, pyrene, fluoranyl or benzophenanthryl.

[0016] Preferably, C3 to C 30 The heteroatom in a heteroaryl group is selected from oxygen, sulfur, or nitrogen.

[0017] Preferably, C3 to C 30 The heteroaryl group is selected from benzofuranyl, benzothiophene, pyridyl, dibenzofuranyl, pyrimidinyl, dibenzothiophene, carbazoyl, N-phenylcarbazoyl, diaryleneamine, benzofuranocarbazoyl, benzofuranothiophene, or triazine.

[0018] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The purpose and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0019] Preferably, the naphthocarbazole compound includes any one of the following compounds:

[0020]

[0021]

[0022]

[0023] Preferably, the naphthocarbazole compound includes any one of the following compounds 1 to 12:

[0024]

[0025] This invention lists some specific structural forms of the naphthocarbazole compounds, but the naphthocarbazole compounds of this invention are not limited to these listed chemical structures. Any structure based on the structure shown in Formula I, where R1 to R3 satisfy the above-mentioned limiting conditions should be included.

[0026] Secondly, the present invention provides the application of the aforementioned naphthocarbazole compounds as electron transport materials for organic electroluminescent devices.

[0027] Thirdly, the present invention provides an organic electroluminescent device, the organic electroluminescent device comprising the naphthocarbazole compound as described in the first aspect.

[0028] Preferably, the organic electroluminescent device includes a first electrode, a second electrode, and an organic layer disposed between the first electrode and the second electrode;

[0029] The organic layer includes the aforementioned naphthocarbazole compounds.

[0030] Preferably, the organic layer includes an electron transport layer;

[0031] The electron transport layer includes the aforementioned naphthocarbazole compounds.

[0032] Fourthly, the present invention provides a display device comprising the organic electroluminescent device as described in the third aspect.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] This invention designs the structure of naphthocarbazole compounds, and the resulting naphthocarbazole compounds, when used as electron transport layer materials in organic electroluminescent devices, can effectively reduce the driving voltage of organic electroluminescent devices, improve the current efficiency of organic electroluminescent devices, and increase the lifespan of organic electroluminescent devices. Detailed Implementation

[0035] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0036] Synthesis Example 1

[0037] This embodiment provides a method for synthesizing compound 1, the method of which is as follows:

[0038]

[0039] (1) Synthesis of intermediate 1-b

[0040] Compound 1-a (40 mmol), pinacol diborate (40 mmol), tris(dibenzylacetone)dipalladium (0.4 mmol), 2-dicyclohexylphosphine-2,4,6-triisopropylbiphenyl (0.8 mmol), potassium acetate (60 mmol), and toluene (300 mL) were added to a reaction flask and heated to reflux for 8 h. The reaction was monitored by TLC (thin-layer chromatography) until complete. After filtration with diatomaceous earth, the mixture was washed with purified water until neutral. The organic phase was concentrated under reduced pressure, and the resulting solid was recrystallized from a mixed solvent of toluene and ethanol to give intermediate 1-b.

[0041] The mass spectrometry data of intermediate 1-b were tested, and the mass spectrometry m / z was measured to be 327.12.

[0042] (2) Synthesis of intermediate 1-c

[0043] 30 mmol of intermediate 1-b, 30 mmol of o-bromobenzaldehyde, 0.6 mol of potassium carbonate, 0.6 mmol of tetra(triphenylphosphine)palladium, 150 mL of water and 1000 mL of dioxane were added to a reaction flask and heated to reflux for 12 h. The reaction was monitored by TLC until complete. Water and dichloromethane were added for extraction. After separating the organic phase, the mixture was concentrated to obtain a solid. The solid was recrystallized from toluene to obtain intermediate 1-c.

[0044] The mass spectrometry data of intermediate 1-c were tested, and the mass spectrometry m / z was measured to be 305.06.

[0045] (3) Synthesis of intermediate 1-d

[0046] 20 mmol of intermediate 1-c, 20 mmol of (methoxymethyl)triphenylphosphine chloride, and 500 mL of tetrahydrofuran were added to a reaction flask. The mixture was cooled to 0 °C, and 25 mmol of potassium tert-butoxide was slowly added. The mixture was kept at this temperature for 30 min, then heated to room temperature and reacted for 4 h at room temperature. The reaction was monitored by TLC until complete. After quenching with ammonium chloride aqueous solution, the mixture was extracted with ethyl acetate. The mixture was separated, and sodium sulfate was added to the organic phase for drying. The sodium sulfate was removed by filtration. Then, 50 mmol of boron trifluoride anisole and 500 mL of dichloromethane were added to the organic phase, and the mixture was stirred for 3 h. After the reaction was completed, dichloromethane and water were added for extraction. The mixture was separated, and sodium sulfate was added to the organic phase for drying. The sodium sulfate was removed by filtration, and the solvent was removed by rotary evaporation. The solid obtained was recrystallized from toluene to give intermediate 1-d.

[0047] The mass spectrometry data of intermediate 1-d were tested, and the mass spectrometry m / z was measured to be 301.07.

[0048] NMR measurements of intermediate 1-d: data are as follows: 1 H-NMR (Bruker, Switzerland, Avance II 400MHz NMR spectrometer, CDCl3), δ 8.88 (d, 1H), δ 8.39 (m, 1H), 8.05 (d, 1H), δ 7.99 (d, 1H), δ 7.94–7.89 (m, 2H), δ 7.84 (s, 1H), δ 7.73–7.62 (m, 3H), 7.33 (d, 1H), δ 7.30 (m, 1H).

[0049] (4) Synthesis of intermediate 1-e

[0050] 40 mmol of intermediate 1-d, 40 mmol of phenylboronic acid, 0.4 mmol of dichlorodi-tert-butyl-(4-dimethylaminophenyl)phosphine palladium(II), 60 mmol of potassium carbonate, and 300 mL of toluene were added to a reaction flask and heated to reflux for 8 h. The reaction was monitored by TLC until complete. After filtration with diatomaceous earth, the mixture was washed with purified water until neutral. The organic phase was concentrated, and the resulting solid was recrystallized with a mixed solvent of toluene and ethanol to obtain intermediate 1-e.

[0051] The mass spectrometry data of intermediate 1-e were tested, and the mass spectrometry m / z was measured to be 343.14.

[0052] (5) Synthesis of Compound 1

[0053] 30 mmol of intermediate 1-e, 30 mmol of 2-chloro-4,6-diphenyl-1,3,5-triazine, 60 mmol of cesium carbonate, and 300 mL of DMF were added to a reaction flask and heated to reflux for 12 h. The reaction was monitored by TLC until it was complete. The reaction solution was poured into water, filtered, and the resulting filter cake was washed with ethanol and recrystallized from toluene to obtain compound 1.

[0054] The mass spectrometry data of compound 1 were tested, and the mass spectrum m / z was measured to be 574.22.

[0055] Synthesis Example 2

[0056] Synthesis of compound 2:

[0057]

[0058] Following the synthetic method of compound 1, 2-chloro-4,6-diphenyl-1,3,5-triazine was substituted for 2,4-bis([1,1'-biphenyl]-4-yl)-6-chloro-1,3,5-triazine in synthetic example 1, while other conditions remained unchanged, to obtain compound 2.

[0059] The mass spectrometry data of compound 2 were tested, and the mass spectrum m / z was measured to be 726.28.

[0060] Synthesis Example 3

[0061] Synthesis of compound 5:

[0062]

[0063] Following the synthetic method of compound 1, 2-chloro-4,6-diphenyl-1,3,5-triazine was substituted with 2-chloro-4-(dibenzo[b,d]furan-3-yl)-6-phenyl-1,3,5-triazine to synthesize the 2-chloro-4,6-diphenyl-1,3,5-triazine in Example 1, with other conditions remaining unchanged, to obtain compound 5.

[0064] The mass spectrometry data of compound 5 were tested, and the mass spectrum m / z was measured to be 664.23.

[0065] Synthesis Example 4

[0066] Synthesis of compound 8:

[0067]

[0068] Following the synthetic method of compound 1, 2-chloro-4,6-diphenyl-1,3,5-triazine was substituted for 2-chloro-4,6-diphenyl-1,3,5-triazine in synthetic example 1, while other conditions remained unchanged, to obtain compound 8.

[0069] The mass spectrometry data of compound 8 were tested, and the mass spectrum m / z was measured to be 680.20.

[0070] Synthesis Example 5

[0071] Synthesis of compound 10:

[0072]

[0073] Following the synthetic method of compound 1, 2-chloro-4,6-diphenyl-1,3,5-triazine was substituted for 2-chloro-4,6-diphenyl-1,3,5-triazine in synthetic example 1, while other conditions remained unchanged, to obtain compound 10.

[0074] The mass spectrometry data of compound 10 were tested, and the mass spectrum m / z was measured to be 790.27.

[0075] Synthesis Example 6

[0076] Synthesis of compound 11:

[0077]

[0078] Following the synthetic method of compound 1, 2-chloro-4,6-diphenyl-1,3,5-triazine was substituted for 2-chloro-4,6-diphenyl-1,3,5-triazine in synthetic example 1, while other conditions remained unchanged, to obtain compound 11.

[0079] The mass spectrometry data of compound 11 were tested, and the mass spectrum m / z was measured to be 690.28.

[0080] Synthesis Example 7

[0081] Synthesis of Compound 12

[0082]

[0083] Following the synthetic method of compound 1, 2-(4-chloro-6-phenyl-1,3,5-triazine-2-yl)-9-phenyl-9H-carbazole was used to replace 2-chloro-4,6-diphenyl-1,3,5-triazine in synthetic example 1, while keeping other conditions unchanged, to obtain compound 12.

[0084] The mass spectrometry data of compound 12 were tested, and the mass spectrum m / z was measured to be 739.27.

[0085] Other compounds for which specific synthesis steps are not listed can be prepared using common knowledge in the art, in conjunction with the above examples.

[0086] The specific structures of some of the compounds used in the following device embodiments and device comparative examples are shown below:

[0087]

[0088]

[0089] Device Example 1

[0090] The examples selected compounds of this application as electron transport materials in organic electroluminescent devices, while the comparative examples selected E1 to E3 as electron transport materials in organic electroluminescent devices.

[0091] The organic electroluminescent device has the following structure:

[0092] ITO / HT (40nm) / BH-1:BD-13% (30nm) / Compound 1 (30nm) / LiF (0.5nm) / Al (150nm).

[0093] The fabrication method of the above-mentioned organic electroluminescent device is as follows:

[0094] The glass substrate coated with an ITO transparent conductive layer (as the anode) was ultrasonically treated in a cleaning agent, then rinsed in deionized water, then ultrasonically degreased in a mixed solvent of acetone and ethanol, then baked in a clean environment until completely dehydrated, cleaned with ultraviolet light and ozone, and bombarded with a low-energy cation beam to improve the surface properties and enhance the bonding ability with the hole injection layer.

[0095] The glass substrate was placed in a vacuum chamber and evacuated to a vacuum level of 1×10⁻⁶. -5 ~9×10 -3 Pa, HT is vacuum-deposited on the anode as a hole transport layer at a deposition rate of 0.1 nm / s and a film thickness of 40 nm;

[0096] A light-emitting layer is vacuum-deposited on top of the hole transport layer at a deposition rate of 0.1 nm / s and a film thickness of 30 nm. The main material of the light-emitting layer is BH-1, and the doping material is BD-1. The 3% refers to the doping ratio of the doping material, that is, the volume ratio of the main material of the light-emitting layer to the doping material is 97:3.

[0097] Compound 1 was vacuum-deposited as an electron transport layer on top of the luminescent layer at a deposition rate of 0.1 nm / s to achieve a film thickness of 30 nm. 0.5 nm of LiF and 150 nm of Al were vacuum-deposited on the electron transport layer as an electron injection layer and a cathode, respectively. The brightness, driving voltage, current efficiency, and lifetime of the fabricated organic electroluminescent device were measured.

[0098] Device Examples 2-7

[0099] Device Examples 2 to 7 each provide an organic electroluminescent device, which differs from Device Example 1 only in that the electron transport material is different (see Table 1 below), while other conditions are the same as those in Device Example 1.

[0100] Device Comparison Examples 1-3

[0101] Comparative Examples 1 to 3 each provide an organic electroluminescent device, which differs from Device Example 1 only in that the electron transport material is different (see Table 1 below), while other conditions are the same as Device Example 1.

[0102] Performance testing

[0103] Test Method: The driving voltage, current efficiency, and lifetime LT90 of the OLED devices provided above were tested. LT90 refers to the time required for the brightness to decrease to 90% of its original brightness while maintaining an initial brightness of 1000 nits at a constant current density. Test items included the brightness, driving voltage, current efficiency, and lifetime LT90 of the organic light-emitting diode. The driving voltage, current efficiency, and LT90 data were all based on a brightness of 1000 cd / m². 2 The relative values ​​at different times (based on device comparison example 1). The performance test results of the organic electroluminescent devices are shown in Table 1 below:

[0104] Table 1

[0105]

[0106]

[0107] As shown in Table 1, this invention has obtained naphthocarbazole compounds through molecular design. The naphthocarbazole compounds provided by this invention can be used as electron transport materials for OLED light-emitting devices, enabling these devices to have lower driving voltage, higher current efficiency, and longer lifetime.

[0108] The present invention has been illustrated with the above embodiments to describe the detailed process flow of the present invention. However, the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A naphthocarbazole compound, characterized in that, The naphthocarbazole compounds include any one of the following compounds: 、 。 2. The application of the naphthocarbazole compounds of claim 1 as electron transport materials for organic electroluminescent devices.

3. An organic electroluminescent device, characterized in that, The organic electroluminescent device includes the naphthocarbazole compound as described in claim 1.

4. The organic electroluminescent device according to claim 3, characterized in that, The organic electroluminescent device includes a first electrode, a second electrode, and an organic layer disposed between the first electrode and the second electrode; The organic layer includes the aforementioned naphthocarbazole compounds.

5. The organic electroluminescent device according to claim 4, characterized in that, The organic layer includes an electron transport layer; The electron transport layer includes the aforementioned naphthocarbazole compounds.

Images