Organic compound containing quinolocarbazole as well as preparation method and application of organic compound

Abstract

The invention provides an organic compound containing quinolocarbazole and a preparation method and application thereof, and belongs to the technical field of organic light-emitting diodes (OLEDs). The organic compound provided by the invention has a structural formula shown in a formula (1), the organic compound is introduced into a hole transport layer of an OLED device, and the hole transport layer is a hole transport layer of the OLED device. According to the OLED device, the mobility and the injection efficiency of holes can be effectively improved, meanwhile, the unbalance condition of the holes and electrons is reduced, the luminous efficiency of the OLED device is effectively improved, the starting voltage is remarkably reduced, and the energy consumption is greatly reduced under the condition of high brightness. And the stability of the device is obviously improved, and the service life is prolonged. The improvement of these properties is mainly benefited from the optimization of hole transport by the compound on the molecular level and the good compatibility of the compound with luminescent layer materials. The compound is not only suitable for a traditional OLED structure, but also can be compatible with a novel flexible display technology, and a brand new solution is provided for a high-performance and low-energy-consumption display device.

Description

Technical Field

[0001] This invention belongs to the field of organic light-emitting diode (OLED) technology, and particularly relates to an organic compound containing quinoline carbazole, its preparation method and application. Background Technology

[0002] Organic light-emitting diodes (OLEDs), as a novel display and lighting technology, have attracted much attention due to their unique performance advantages. OLEDs possess advantages such as self-illumination, wide viewing angle, fast response speed, and the ability to achieve flexible displays, and are widely used in smartphones, tablets, televisions, smart wearable devices, and other fields. However, despite the significant progress made in OLED technology, some key challenges remain regarding device efficiency, which limit its further development and wider application.

[0003] The fundamental principle of OLEDs is based on the electroluminescence phenomenon of organic materials. When current passes through an organic thin film, electrons and holes are injected into the organic layers from the cathode and anode, respectively, and recombine in the emissive layer (EML) to form excitons. The decay of these excitons is accompanied by the emission of photons, thus achieving light emission. A typical OLED structure includes an anode, a hole injection layer (HIL), a hole transport layer (HTL), an emissive layer (EML), an electron transport layer (ETL), and a cathode. This multilayer structure is designed to optimize carrier injection and transport efficiency, thereby improving the overall performance of the device.

[0004] Despite the tremendous success of OLED technology in the display field, device efficiency remains a critical issue that needs to be addressed in practical applications. Insufficient device efficiency not only affects the display quality of OLEDs but also limits their potential in high-brightness, low-power applications.

[0005] In OLED devices, carrier injection imbalance, luminous efficiency limitations, excessively high start-up voltage, and insufficient device lifetime and stability are key issues affecting performance. The mismatch between hole and electron injection rates leads to reduced exciton formation efficiency in the emissive layer, thus affecting luminous efficiency. Furthermore, the presence of nonradiative recombination processes and insufficient luminous quantum efficiency of the emissive layer material also limit the device's luminous performance. High start-up voltage not only increases energy consumption but also leads to performance instability at low brightness, affecting device lifespan. Simultaneously, material degradation, interface aging, and corrosion from oxygen and moisture pose challenges to device lifetime and stability. These issues restrict the further development of OLED technology in applications requiring high brightness, low energy consumption, and long lifespan.

[0006] While various methods exist to improve the efficiency and performance of OLED devices, these methods still have some limitations. For example, some high-performance hole and electron transport materials, although capable of improving carrier injection efficiency, often require complex synthesis processes and incur high costs. Furthermore, some luminescent materials, while possessing high luminous efficiency, may be limited in practical devices by interface effects and stability issues. Therefore, developing new materials or structures that can effectively address these problems is of great significance for improving the overall performance of OLED devices. Summary of the Invention

[0007] In view of this, the purpose of this invention is to provide an organic compound containing quinocarbazole, its preparation method, and its applications. This invention introduces an organic compound containing quinocarbazole into the hole transport layer of an OLED device, which effectively improves hole mobility and injection efficiency while reducing the imbalance between holes and electrons. Using the organic compound of this invention, the luminous efficiency of the OLED device is effectively improved, the start-up voltage is significantly reduced, and energy consumption is greatly reduced under high brightness conditions. Furthermore, the stability of the device is significantly improved, and its lifespan is extended. These performance improvements are mainly due to the optimization of hole transport at the molecular level and its good compatibility with the emissive layer material. The compound of this invention is not only applicable to traditional OLED structures but also compatible with novel flexible display technologies, providing a new solution for high-performance, low-energy-consumption display devices.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides an organic compound comprising quinoline carbazole, having the structural formula shown in formula (1): Formula (1), wherein R1 and R2 are the same or different and are each independently selected from hydrogen, C1-C4 alkyl-substituted or terminally substituted C1-C4 alkyl, C2-C4 alkyl-substituted or terminally substituted C1-C4 alkyl-substituted or terminally substituted C2-C4 alkynyl, C6-C14 aryl containing one or more substituents R1 or unsubstituted aryl, aryl group, C5-C8 aromatic heterogroup containing one or more heteroatoms with one or more substituents R1 or unsubstituted aryl. R1 can also be independently selected from fluorine (F), chlorine (CI), bromine (Br), iodine (I), cyano (CN), and C1-C8 alkyl groups.

[0009] The present invention also provides the above-described organic compounds containing quinoline carbazole, selected from any one of the compounds shown in the following structural formulas:

[0010] .

[0011] This invention also provides a method for preparing the above-mentioned organic compound containing quinoline carbazole, wherein the preparation method is carried out according to the following synthetic route: .

[0012] The present invention also provides the application of the above-mentioned organic compounds containing quinoline carbazole in the preparation of organic electroluminescent devices.

[0013] The present invention also provides the application of the above-mentioned organic compounds containing quinoline carbazole in the preparation of organic electroluminescent devices (OLEDs).

[0014] This invention, by introducing the aforementioned organic compound containing quinoline carbazole, significantly improves carrier injection balance, optimizes luminous efficiency of the emissive layer, reduces startup voltage, and enhances device stability and lifetime. The compound of this invention possesses a unique molecular structure that effectively improves hole and electron injection characteristics, while exhibiting good compatibility with existing OLED fabrication processes and material systems. Through the innovation of this invention, it is expected to provide an efficient and low-cost solution for the development of OLED technology, further promoting its widespread application in the display and lighting fields. Attached Figure Description

[0015] Figure 1 This is a structural diagram of an organic electroluminescent device. Detailed Implementation

[0016] This invention provides an organic compound comprising quinoline carbazole, having the structural formula shown in formula (1): Formula (1), wherein R1 and R2 are the same or different and are each independently selected from hydrogen, C1-C4 alkyl-substituted or terminally substituted C1-C4 alkyl, C2-C4 alkyl-substituted or terminally substituted C1-C4 alkyl-substituted or terminally substituted C2-C4 alkynyl, C6-C14 aryl containing one or more substituents R1 or unsubstituted aryl, aryl group, C5-C8 aromatic heterogroup containing one or more heteroatoms with one or more substituents R1 or unsubstituted aryl. R1 can also be independently selected from fluorine (F), chlorine (CI), bromine (Br), iodine (I), cyano (CN), and C1-C8 alkyl groups.

[0017] The present invention also provides the above-described organic compounds containing quinoline carbazole, selected from any one of the compounds shown in the following structural formulas:

[0018] .

[0019] This invention also provides a method for preparing the above-mentioned organic compound containing quinoline carbazole, wherein the preparation method is carried out according to the following synthetic route: .

[0020] The present invention also provides the application of the above-mentioned organic compounds containing quinoline carbazole in the preparation of organic electroluminescent devices.

[0021] The present invention also provides the application of the above-mentioned organic compounds containing quinoline carbazole in the preparation of organic electroluminescent devices (OLEDs).

[0022] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0023] Example 1 Preparation method of organic compound WQ1 containing quinoline carbazole: , The synthetic methods for compound S1 include: Under nitrogen protection, substrate A (1 eq.), substrate B (1.3 eq.), Pd(PPh3)4 (0.1 eq.), and potassium carbonate (4 eq.) were added sequentially to a three-necked flask. The solution was added in a toluene:water:ethanol ratio of 3:2:1, and the mixture was heated to 80°C and reacted overnight. After the reaction was stopped, the mixture was cooled to room temperature, filtered, extracted, and the organic phase was collected. The solvent was removed by vacuum distillation, and the mixture was purified using a normal silica gel column chromatography.

[0024] The synthetic methods for compound S2 include: Under nitrogen protection, S1 (1 eq.), [Cp*IrCl2]2 (0.02 eq.), Cu(OAc)2 (0.2 eq.), tert-butyric acid (2 eq.), methylnaphthalene (30 mg), and free radical scavenger (0.2 eq.) were added sequentially to a three-necked flask. After adding NMP solvent, the apparatus was set up and the temperature was raised to 120 °C for 3 hours. After the reaction was stopped, the temperature was lowered to room temperature, the reaction mixture was filtered, extracted, and the organic phase was collected. The solvent was removed by vacuum distillation, and the organic phase was purified using a normal silica gel column chromatography.

[0025] The synthetic methods for compound S3 include: Preparation of carbazole magnesium chloride: In a 200 mL four-necked round-bottom flask equipped with a Teflon®-coated magnetic stir bar, condenser, dropping funnel, thermometer, and three-way stopcock, the flask was purged with nitrogen and then filled with nitrogen. S2 (1.03 eq.), dried xylene (1.03 eq. per 55 mL of S2), and dried tetrahydrofuran (1.03 eq.) were added sequentially to the flask. The resulting white slurry was cooled to 5°C in an ice-water bath. A tetrahydrofuran solution containing 3.39 eq. of MeMgCl (1.02 eq.) was placed in a dropping funnel and added dropwise to the slurry over 10 minutes at a rate maintaining the internal temperature at 20°C or lower, while vigorous stirring under nitrogen protection. The slurry dissolved rapidly, accompanied by the formation of methane bubbles, yielding a carbazole magnesium chloride solution (1.02 eq.). (eq.), which contains trace amounts of carbazole as a dark gray liquid, and then the dropping funnel is washed with dry xylene (11 ml per gram of S2, 1 volume); Coupling reaction: Substrate C (1.0 eq.) and a Pd-CBRDIP catalyst solution (containing 0.05 to 0.3 mol% catalyst) were added to the carbazole magnesium chloride solution prepared above. The mixture was then vigorously stirred in a silicone oil bath under nitrogen protection and heated to reflux temperature (108 to 112°C). As the coupling reaction proceeded, magnesium salts precipitated. The reaction mixture was stirred under reflux until the substrate was completely consumed (approximately 15 minutes). The progress of the reaction could be checked by gas chromatography (GC) by washing the reaction mixture dilution in toluene with a saturated aqueous solution of ammonium chloride. After the reaction was stopped, the reaction mixture was cooled to room temperature using a water bath, and then tap water and ammonium chloride (0.5 eq.) were added to the mixture. The mixture was stirred at room temperature for 10 minutes, and then insoluble matter was removed by vacuum filtration using filter paper and Celite®. The aqueous layer was separated from the filter cake using a separating funnel. The filter cake was concentrated under vacuum to obtain the residue, which could be decolorized and recrystallized by silica gel or purified by silica gel column chromatography to obtain the coupling product S3.

[0026] The synthetic methods for compound S4 include: Under nitrogen protection, S3 and substrate D were added to a clean, dry three-necked flask, the apparatus was assembled, and S3 was refluxed in substrate D (1.3 eq.) overnight. After the reaction was stopped, the reaction was cooled to room temperature, and excess substrate D was removed by vacuum distillation. The remaining crude product could be purified by silica gel column chromatography to obtain product S4.

[0027] The synthetic methods for compound S5 include: Under nitrogen protection, S4 was added to a dry, clean three-necked flask and dissolved in dry DCM. Trimethylbromosilane (2.2 eq.) was slowly added dropwise in an ice bath. The reaction was stirred overnight at room temperature. After overnight reaction, the reaction was stopped and quenched dropwise with methanol in an ice bath. The solvent was removed by vacuum distillation. The remaining crude product could be decolorized and recrystallized by silica gel or purified by silica gel column chromatography to obtain the final product S5 (i.e., organic compound WQ1).

[0028] Example 2 This embodiment provides an organic electroluminescent device, the structure of which is described in [reference needed]. Figure 1 The preparation method is as follows: The ITO substrate is patterned to have a light-emitting area of ​​2mm × 2mm, then washed with isopropanol, UV, and ozone respectively. Afterwards, the ITO substrate is mounted on the substrate support of a vacuum deposition apparatus, and the pressure is adjusted to make the vacuum rate 1 × 10⁻⁶. -7 First, a hole injection layer is formed on the ITO layer (anode) formed on the substrate by vacuum deposition of compounds WQ1 and HT-1 (mass ratio of WQ1 to HT-1 is 3:97) provided in Synthesis Example 1 of the present invention, with a thickness of 10 nm. Next, a hole transport layer is formed on the hole injection layer by vacuum deposition of compound HT-1 with a thickness of 110 nm. Then, an electron blocking layer is formed on the hole transport layer by vacuum deposition of compound EB-1 with a thickness of 10 nm. Finally, a mixture of compounds BD-1 and BH is vacuum deposited on the electron blocking layer with a thickness of 20 nm. An organic electroluminescent device is fabricated by forming a light-emitting layer (the mass ratio of compound BD-1 to compound BH is 3:97); then, a hole-blocking layer is formed on the light-emitting layer by vacuum deposition of compound HB-1 with a thickness of 5 nm; next, an electron transport layer is formed on the hole-blocking layer by vacuum deposition of compound ET-1 and Liq (the mass ratio of compound ET-1 to Liq is 5:5) with a thickness of 30 nm; then, an electron injection layer is formed on the electron transport layer by depositing LiF with a thickness of 1 nm; finally, an electron cathode is formed on the electron injection layer by depositing aluminum (Al) with a thickness of 150 nm.

[0029] Apart from the material WQ1 used in this invention, the molecular structural formulas of the other layers of the device are as follows:

[0030] The electrode preparation method and the deposition method of each functional layer in this embodiment are conventional methods in the art, such as vacuum thermal evaporation or inkjet printing, and will not be described in detail here.

[0031] Example 3 The preparation method is the same as in Device Example 2, except that compound WQ1 in the hole injection layer is replaced with compound WQ2, and the mass ratio of compound WQ2 to HT-1 in the hole injection layer is 3:97.

[0032] Example 4 The preparation method is the same as in Device Example 2, except that compound WQ1 in the hole injection layer is replaced with compound WQ3, and the mass ratio of compound WQ3 to HT-1 in the hole injection layer is 3:97.

[0033] Comparative Example 1 The preparation method is the same as in Device Example 2, except that compound WQ1 in the hole injection layer is replaced with compound PA1, and the mass ratio of compound PA1 to HT-1 in the hole injection layer is 3:97.

[0034] Comparative Example 2 The preparation method is the same as in Device Example 2, except that compound WQ1 in the hole injection layer is replaced with compound PA2, and the mass ratio of compound PA2 to HT-1 in the hole injection layer is 3:97.

[0035] Comparative Example 3 The preparation method is the same as in Device Example 2, except that compound WQ1 in the hole injection layer is replaced with compound PA3, and the mass ratio of compound PA3 to HT-1 in the hole injection layer is 3:97.

[0036] Device performance The organic electroluminescent devices provided in Device Examples 2-4 and Device Comparative Examples 1-3 were tested using standard methods. For this purpose, J = 10 mA / cm² was used. 2 The driving voltage and current efficiency (CE) of the organic electroluminescent device were determined at a current density of J = 25 mA / cm². 2 The lifetime (LT95) of the organic electroluminescent device was determined at a given current density.

[0037] The testing instruments and methods used to perform performance testing on the above-mentioned OLED devices are as follows: Brightness was tested using a PhotoResearch PR-635 spectral scanner; Current density and turn-on voltage: tested using a Keithley 2400 digital source meter; Lifetime testing: Using a silicon photonics-based OLED device lifetime testing system.

[0038] The performance test results of the above devices are listed in Table 1.

[0039] Table 1 Device performance test results

[0040] The device performance test results in Table 1 above show that: The organic electroluminescent devices in Examples 2-4 prepared using the compounds provided by this invention have lower driving voltages than those in Comparative Example 1, while also exhibiting higher current efficiency and lifetime, demonstrating that the organic compounds of this invention have excellent hole injection capabilities as hole injection layer doping materials.

[0041] Compared with the organic electroluminescent devices provided in Comparative Examples 2 and 3, the organic electroluminescent devices of Examples 2-4 prepared using the organic compounds provided by this invention show varying degrees of improvement in driving voltage, current efficiency, and lifetime. Specifically, compared with the organic electroluminescent device provided in Comparative Example 2, the driving voltage of the organic electroluminescent devices of Examples 2-4 prepared using the organic compounds provided by this invention is reduced by 9% to 11.0%, the current efficiency is increased by 18.0% to 21.0%, and the lifetime is increased by 10.0% to 12.3%. Compared with the organic electroluminescent device provided in Comparative Example 3, the driving voltage of the organic electroluminescent devices of Examples 2-4 prepared using the organic compounds provided by this invention is reduced by 7.2% to 8.9%, the current efficiency is increased by 17.3% to 20.5%, and the lifetime is increased by 11.7% to 26.1%. This indicates that the quinocarbazole structure in the compound structure of this invention can better improve the doping ability of the material in the hole injection layer, reduce the device voltage, and improve the device efficiency and lifetime.

[0042] Based on the device examples 2-4 and device comparative examples 1-3 described above, the following conclusions can be drawn: The organic electroluminescent devices provided by this invention have significant advantages in luminescence performance, generally exhibiting high BI values ​​and long lifetimes, and more importantly, high thermal stability. This is because the compounds provided by this invention all adopt a quinocarbazole structure. The mutual repulsion of the lone pairs of electrons in the nitrogen atoms in the structure increases the intermolecular distance, improves the fluorescence quantum yield, and contributes to the improvement of device efficiency and the extension of lifetime. In addition, by adopting this non-planar quinocarbazole structural design, the thermal stability of the molecule is increased, and the rigidity of the molecule is increased, indirectly reducing the problem of device performance degradation due to heat generation, thus improving device efficiency and lifetime.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An organic compound comprising quinolinecarbazole, characterized in that, It has the structural formula shown in equation (1): Equation (1), Wherein R1 and R2 may be the same or different, and each is independently selected from hydrogen, C1-C4 alkyl-substituted or terminally substituted C1-C4 alkyl, C2-C4 alkylene-substituted or terminally substituted C1-C4 alkylene-substituted or terminally substituted C2-C4 alkynyl, C6-C14 aryl containing one or more substituents R1 or unsubstituted aryl, aryl group, and C5-C8 aromatic heterogroup containing one or more heteroatoms containing one or more substituents R1 or unsubstituted aryl. R1 can also be independently selected from fluorine (F), chlorine (CI), bromine (Br), iodine (I), cyano (CN), and C1-C8 alkyl groups.

2. An organic compound comprising quinoline carbazole according to claim 1, characterized in that, The organic compound containing quinoline carbazole is selected from any one of the compounds shown in the following structural formulas: 。 3. A method for preparing an organic compound containing quinoline carbazole as described in claim 1 or 2, characterized in that, The preparation method follows the synthetic route described below: 。 4. The use of an organic compound containing quinoline carbazole as described in claim 1 or 2 in the preparation of organic electroluminescent devices.

5. The use of an organic compound containing quinoline carbazole as described in claim 1 or 2 in the preparation of organic light-emitting devices (OLEDs).

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