A fluorenyl acridine compound, and a preparation method and application thereof

Abstract

The application discloses a fluorenyl acridine compound and a preparation method and application thereof, and belongs to the technical field of organic electroluminescence. The fluorenyl acridine compound has a structure shown in general formula 1, wherein R1 and R2 are any one of substituted or unsubstituted boron-nitrogen heterocyclic groups, boron-oxygen heterocyclic groups, oxygen-nitrogen heterocyclic groups, sulfur-nitrogen heterocyclic groups, oxygen-sulfur-nitrogen heterocyclic groups, oxygen-boron-nitrogen heterocyclic groups, sulfur-boron-nitrogen heterocyclic groups and selenium-boron-nitrogen heterocyclic groups. The organic electroluminescence material can be applied to a solution processing 0LED process as a narrow-spectrum luminescent material, effectively improves the aggregation-induced fluorescence quenching effect caused by a fused ring rigid planar structure and the aggregation-caused half-peak width broadening defect, reduces the half-peak width, and makes the luminescent performance and color purity of the device in the luminescent process not only not reduced but also greatly improved.

Description

Technical Field

[0001] This invention relates to the field of organic electroluminescence technology, and in particular to a fluorenyl acridine compound, its preparation method, and its application. Background Technology

[0002] Organic electroluminescent materials and devices have broad application prospects in flat panel displays and solid-state lighting. Among them, the boron-nitrogen (BN)-based multi-resonance thermally activated delayed fluorescence molecule is an organic light-emitting material with narrow spectral luminescence characteristics and high efficiency. This type of organic light-emitting material has important application value in the future ultra-high-definition display field.

[0003] While the preparation of boron-nitrogen organic light-emitting materials using vacuum evaporation is relatively mature, the number of boron-nitrogen materials suitable for production is still relatively small, warranting further attention and research. This is mainly because boron-nitrogen light-emitting materials generally possess a rigid molecular structure. This rigidity hinders their dissolution and solution processing for film formation and easily leads to strong molecular aggregation, resulting in a redshift and broadening of their emission spectra. In the field of organic electroluminescence, the light-emitting material is a key factor determining the performance of OLED devices. Currently, solution-processable MR-TADF light-emitting materials are scarce, and further breakthroughs are urgently needed.

[0004] In solution-processed OLED devices, the hole injection layer, hole transport layer, and emissive layer are typically formed sequentially onto the anode via spin coating or inkjet printing, while the hole blocking layer, electron transport layer, electron injection layer, and cathode are generally deposited via vapor deposition. The emissive layer typically comprises a host material and a luminescent material. Luminescent materials suitable for solution-processed OLEDs, or those applicable to both vacuum deposition and solution processing, need to have good solubility in organic solvents. Furthermore, to reduce device efficiency roll-off and suppress emission redshift and spectral broadening, the luminescent material must not accumulate excessively during thin film formation. However, there are relatively few solution-processed MR-TADF luminescent materials that meet these requirements, and related organic electroluminescent materials and devices require further attention and in-depth research. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings and deficiencies of the prior art by proposing a fluorenyl acridine compound, its preparation method, and its applications. OLEDs prepared using this novel TADF material achieve high photoelectric conversion efficiency, long lifespan, and reduced costs. This invention is easily modifiable, allows for control of the overall molecular weight, and can be applied to OLED fabrication using spin-coating processes.

[0006] The technical solution adopted by this invention to solve its technical problem is: This invention provides a fluorenyl acridine compound having the structure shown in general formula 1:

[0007] Wherein, R1 and R2 are any one of the following: boron-nitrogen heterocyclic group, boron-oxygen heterocyclic group, oxynitrogen heterocyclic group, sulfur-nitrogen heterocyclic group, oxysulfur-nitrogen heterocyclic group, oxyboron-nitrogen heterocyclic group, sulfur-boron-nitrogen heterocyclic group, and selenium-boron-nitrogen heterocyclic group, whether substituted or unsubstituted.

[0008] In one respect, the fluorenyl acridine compound has any one of the following structures:

[0009] In one respect, the fluorenyl acridine compound is prepared by the following method: Step 1: Raw material 1 undergoes a nucleophilic substitution reaction to generate intermediate 1;

[0010] Step 2: Intermediate 1 is then subjected to the Suzuki coupling reaction to generate the final product, general formula 1;

[0011] In another aspect, the present invention provides an organic electroluminescent composition comprising the above-described fluorenyl acridine compound or a fluorenyl acridine compound obtained by the above-described method for preparing the fluorenyl acridine compound.

[0012] In one aspect, the present invention provides an organic electroluminescent device, comprising an anode, a cathode, and an organic thin film layer disposed between the anode and the cathode; the organic thin film layer comprises a light-emitting layer, a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer; wherein the light-emitting layer comprises the aforementioned fluorenyl acridine compound or a fluorenyl acridine compound obtained by the aforementioned method of preparing the aforementioned fluorenyl acridine compound or the aforementioned organic electroluminescent composition.

[0013] In another aspect, the present invention provides an application of the above-mentioned organic electroluminescent device as a narrow-spectrum OLED device in a solution processing technology.

[0014] The technical solution of the present invention has the following advantages: The fluorenylacridine compound provided in this invention exhibits a unique twisted molecular structure by attaching multiple BN luminescent core units to the fluorenylacridine backbone. This twisted structure enhances the solubility of the organic material in organic solvents, enabling its application in solution processing. Furthermore, it helps suppress the accumulation of luminescent molecules, thereby reducing device efficiency roll-off and spectral redshift and broadening caused by molecular accumulation. In addition, the fluorenylacridine compound in this invention possesses a BN molecular core backbone and exhibits narrow-band luminescence, effectively improving the color purity of the device.

[0015] In this invention, the fluorenyl acridine compound links multiple BN luminescent backbone core units together via fused-ring groups, resulting in a fluorenyl acridine compound with a twisted molecular structure. Compared to unlinked fluorenyl acridine compounds, the fluorenyl acridine compound with the twisted molecular structure exhibits improved solubility. Furthermore, when used as a guest in organic light-emitting devices, the fluorenyl acridine compound with the twisted molecular structure of this invention exhibits suppressed spectral broadening and redshift, as well as suppressed efficiency roll-off.

[0016] The TADF material provided by this invention exhibits excellent thermal stability, with a glass transition temperature greater than 120℃ and a thermal decomposition temperature greater than 500℃. Furthermore, it can be used to prepare blue light-emitting devices through spin coating, expanding the processing methods of TADF material. Therefore, the novel TADF material provided by this invention has broad market application prospects and is easily applicable to large-scale industrial production.

[0017] Furthermore, the present invention includes an organic electroluminescent device comprising an anode, a cathode, and an organic layer, wherein the organic layer comprises a TADF material of a fluorenyl acridine compound.

[0018] Furthermore, the organic electroluminescent device of the present invention includes an anode, a cathode, and an organic thin film layer disposed between the anode and the cathode; the organic thin film layer includes a light-emitting layer, a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer.

[0019] The light-emitting layer comprises a fluorenyl acridine compound or a fluorenyl acridine compound prepared by a method thereof.

[0020] Furthermore, the present invention includes the application of organic electroluminescent devices in organic light-emitting diodes, organic photovoltaic cells, organic light-emitting cells, organic field-effect transistors, organic light-emitting field-effect transistors, organic lasers, organic spintronic devices, organic sensors, and organic polariton emission diodes.

[0021] Beneficial effects: 1. This invention achieves high photoelectric conversion efficiency, long service life, and reduced costs.

[0022] 2. This invention is easy to modify and can be applied to the spin coating process for OLED fabrication.

[0023] 3. The organic electroluminescent material of this invention can be applied as a narrow-spectrum luminescent material in solution-processed LED technology. It can effectively improve the aggregation-induced fluorescence quenching effect caused by the rigid planar structure of boron-nitrogen fused rings and the deficiency of aggregation-induced widening of the half-width at half-maximum. It reduces the half-width at half-maximum, so that the luminescence performance and color purity of the device are not only not reduced during the luminescence process, but are also greatly improved. Detailed Implementation

[0024] To facilitate understanding, the technical solutions and implementation methods of the present invention will be further described clearly, completely, and in detail below through specific embodiments. It should be understood that the embodiments described herein are implemented based on the technical solutions of the present invention, providing detailed implementation methods and specific operating procedures. However, these are only some embodiments of the present invention, not all embodiments. The specific implementation methods described are limited to illustrating and explaining the present invention and do not limit the present invention. All other implementation methods obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used in the examples are commercially available unless otherwise specified.

[0026] An embodiment of the present invention provides a fluorenyl acridine compound having the structure shown in general formula 1:

[0027] The fluorenyl acridine compounds of this invention exhibit a special twisted molecular structure by connecting multiple BN luminescent backbone core units to fused ring groups. This twisted structure of the fluorenyl acridine compounds can, on the one hand, improve the solubility of organic materials in organic solvents, thus enabling their application in solution processing; on the other hand, it helps to suppress the accumulation of luminescent molecules, thereby reducing the efficiency roll-off of devices and the spectral redshift and spectral broadening caused by molecular accumulation.

[0028] In some embodiments of the present invention, the fluorenyl acridine compound is selected from any one of the following compounds:

[0029] According to an embodiment of the present invention, a method for preparing the above-mentioned fluorenyl acridine compound is provided, comprising: Step 1: Raw material 1 undergoes a nucleophilic substitution reaction to generate intermediate 1, as shown in the following reaction formula:

[0030] Step 2: Intermediate 1 undergoes the Suzuki coupling reaction to generate the final product, general formula 1, as shown in the following reaction formula:

[0031] In some embodiments of the present invention, the reaction conditions for synthesizing intermediate 1 are as follows: Step 1: Mix raw material 1 (1.0 eq), Cul (0.5 eq), K3PO4 (2.5 eq), iodobenzene (1.0 eq) and ethylenediamine (1.0 eq), add to toluene solvent, reflux and stir for 12 hours under nitrogen atmosphere, cool to room temperature and purify by column chromatography to obtain intermediate 1.

[0032] In some embodiments of the present invention, the reaction conditions for the final product of general formula 1 are as follows: Step 2: Intermediate 1 (1 eq), fused ring group (2.1 eq), K3PO4 (5 eq), water and toluene were placed under nitrogen protection. After 20 minutes, tetraphenyl palladium (1%) was added, and the mixture was heated to 60°C and stirred under reflux for 12 hours. After cooling to room temperature, it was purified by column chromatography to obtain general formula 1.

[0033] According to an embodiment of the present invention, an organic electroluminescent material is provided, which comprises the above-mentioned fluorenyl acridine compound or the fluorenyl acridine compound obtained by the above-mentioned method for preparing the fluorenyl acridine compound.

[0034] According to an embodiment of the present invention, an organic electroluminescent device is provided, comprising an anode, a cathode, and an organic thin film layer disposed between the anode and the cathode; the organic thin film layer comprises a light-emitting layer, a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer; wherein the light-emitting layer comprises the above-mentioned fluorenyl acridine compound or a fluorenyl acridine compound obtained by the above-mentioned method for preparing the fluorenyl acridine compound or the above-mentioned organic electroluminescent composition.

[0035] In some embodiments of the present invention, an organic electroluminescent device includes an anode and a cathode, and an organic thin film layer disposed between the anode and the cathode. The organic thin film layer includes a light-emitting layer, an optional hole injection layer, an optional hole transport layer, an optional electron transport layer, and an optional electron injection layer. The light-emitting layer comprises a host material and a light-emitting material. The light-emitting layer, hole injection layer, and hole transport layer are prepared using a spin coating process or an inkjet printing process, while the electron transport layer, electron injection layer, and cathode are prepared using a vacuum evaporation process.

[0036] In some embodiments of the present invention, compounds having the structure shown in Formula 1 can serve as guest light-emitting materials in the light-emitting layer. The light-emitting layer also contains a host material.

[0037] In some embodiments of the present invention, the organic electroluminescent device may further include an optional hole blocking layer, an optional electron blocking layer, and an optional capping layer, etc.

[0038] In some embodiments of the present invention, fluorenyl acridine compounds can be used as guest light-emitting materials in the light-emitting layer of an organic electroluminescent device, wherein the organic electroluminescent device contains a hole injection layer, optionally a hole transport layer, one or more electron transport layers, and a light-emitting layer. Further, when the compound of the present invention is used as a guest light-emitting material in the light-emitting layer, the mass ratio of the compound in the light-emitting layer is 0.1% to 20%.

[0039] According to an embodiment of the present invention, an application of the above-described organic electroluminescent device is provided, wherein the organic electroluminescent device is used as a narrow-spectrum OLED device in a solution-processed OLED process.

[0040] To further illustrate the effects of the present invention, specific embodiments are described below.

[0041] In embodiments of the present invention, the specific raw materials used to synthesize the final product structural formula 2 are as follows:

[0042] The following compounds were prepared using the same synthetic method as that used for structural formula 2.

[0043] In this invention, fluorenyl acridine compounds link multiple BN luminescent backbone core units together via fused-ring groups to obtain fluorenyl acridine compounds with a twisted molecular structure. Compared to unlinked fluorenyl acridine compounds (e.g., BN), the solubility of the fluorenyl acridine compounds with a twisted molecular structure (e.g., 2, 16, 30) in this invention is significantly improved.

[0044] Examples of electroluminescent devices Device Example 1: The pre-fabricated ITO glass was ultrasonically cleaned with cleaning solution, deionized water, and isopropanol for 15 minutes in sequence and then dried in a 70°C oven. The dried ITO glass was then treated with an ultraviolet ozone cleaner for 15 minutes. After that, 200 μL of PEDOT:PSS solution was dropped onto the ITO glass and spin-coated at 2000 rpm / min for 40 seconds. Then, it was annealed and dried at 150°C for 15 minutes to form a hole injection layer with a thickness of 40 nm. Compound α was selected as the host material, and the aforementioned luminescent material of structural formula 1 was selected as the luminescent guest. Both were dissolved in chlorobenzene solvent at a certain mass ratio to form a first mixture with a concentration of 15 mg / ml. This first mixture was filtered through a PTFE membrane with a 0.22 μm filter diameter to form a second mixture. 100 μL of the second mixture was dropped onto the hole injection layer and spin-coated at 1500 rpm / min for 30 seconds. The mixture was then annealed and dried at 80°C for 60 minutes to form a 40 nm thick luminescent layer. The unfinished device was transferred to a vapor deposition chamber. Under a vacuum atmosphere of 3 × 10⁻⁵ Pa, an electron transport layer with a thickness of 30 nm was formed at a rate of 0.05 nm / s. The electron transport layer material was TmPyPB. An electron injection layer with a thickness of 2 nm was formed at a rate of 0.01 nm / s. The electron injection layer material was (8-hydroxyquinoline)lithium. A cathode layer was formed at a rate of 0.02 nm / s. The cathode layer was metallic aluminum. An organic electroluminescent device was thus obtained.

[0045] The structural formula of compound α is as follows:

[0046] Device Examples 2-12:

[0047] By comparing the device performance of the examples and comparative examples in Table 2, the following conclusions can be drawn: When the fluorenyl acridine compound of this invention is used as a light-emitting guest material for solution-processed OLED devices, it has better solubility than the comparative material BN. The organic electroluminescent device achieves higher maximum efficiency and maintains better color (half-maximum width at half maximum). At the same time, it maintains higher efficiency at higher brightness and can effectively suppress spectral broadening caused by increasing doping concentration. This is beneficial for expanding the process window of the material in device fabrication and makes it more applicable.

[0048] In this invention, the fluorenyl acridine compounds link multiple BN luminescent backbone core units together via fused-ring groups, resulting in fluorenyl acridine compounds with a distorted molecular structure. Compared to unlinked fluorenyl acridine compounds (e.g., BN), the fluorenyl acridine compounds with the distorted molecular structure of this invention, when used as guest components in organic light-emitting devices, suppress spectral broadening and redshift, as well as efficiency roll-off.

[0049] In summary, the fluorenyl acridine compound provided in this embodiment of the invention can be used as an organic electroluminescent material in solution-processed OLED technology as a narrow-spectrum light-emitting material, and the corresponding solution-processed organic electroluminescent devices show a significant improvement in color purity.

[0050] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0051] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fluorenyl acridine compound, characterized in that, The fluorenyl acridine compound has the structure shown in general formula 1: R1 and R2 are any one of the following: substituted or unsubstituted boron-nitrogen heterocyclic group, boron-oxygen heterocyclic group, oxynitrogen heterocyclic group, sulfur-nitrogen heterocyclic group, oxysulfur-nitrogen heterocyclic group, oxyboron-nitrogen heterocyclic group, sulfur-boron-nitrogen heterocyclic group, and selenium-boron-nitrogen heterocyclic group.

2. The fluorenyl acridine compound according to claim 1, characterized in that, The compound is any one of the following structures:

3. A fluorenyl acridine compound according to claim 1 or 2, characterized in that, The fluorenyl acridine compound is prepared by the following method: Step 1: Raw material 1 undergoes a nucleophilic substitution reaction to generate intermediate 1; Step 2: Intermediate 1 is then subjected to the Suzuki coupling reaction to generate the final product, general formula 1; 4. An application of the fluorenyl acridine compound according to claim 1 in an organic electroluminescent device.

5. An organic electroluminescent device, comprising an anode, a cathode, and an organic layer, characterized in that, The organic layer comprises a TADF material containing a fluorene-acridine compound.

6. The organic electroluminescent device according to claim 5, characterized in that, The organic electroluminescent device includes an anode, a cathode, and an organic thin film layer disposed between the anode and the cathode; The organic thin film layer includes a light-emitting layer, a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer; The light-emitting layer comprises a fluorenyl acridine compound or a fluorenyl acridine compound obtained according to the preparation method described in claim 3.

7. The organic electroluminescent device according to claim 6, characterized in that, The mass percentage of the fluorenyl acridine compound or the fluorenyl acridine compound obtained by the preparation method according to claim 3 in the luminescent layer is 0.1% to 20%.

8. An application of the organic electroluminescent device as described in claim 5 or 6, characterized in that, This includes the application of organic electroluminescent devices in organic light-emitting diodes, organic photovoltaic cells, organic light-emitting cells, organic field-effect transistors, organic light-emitting field-effect transistors, organic lasers, organic spintronic devices, organic sensors, and organic plasma-emitting diodes.

9. The application of the organic electroluminescent device according to claim 8, characterized in that, Organic electroluminescent devices are used as narrow-spectrum OLED devices in solution processing.

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