Red light emitting material and preparation method and application thereofTechnical Field
The invention belongs to the technical field of organic luminescent materials, and particularly relates to a red luminescent material, and a preparation method and application thereof.
Background
Organic Light Emitting Diodes (OLEDs) have great application prospects in the fields of flat panel displays, solid-state light sources, and the like, due to their advantages of full solid state, self-luminescence, wide viewing angle, fast response, low driving voltage, low power consumption, and the like. At present, although research on the OLED has been significantly progressed, the traditional luminescent materials of the OLED mainly comprise fluorescent materials and phosphorescent materials, namely, the first generation OLED based on the fluorescent luminescent materials only utilizes singlet excitons to emit light, the Internal Quantum Efficiency (IQE) of the first generation OLED is only 25%, the second generation OLED is based on the phosphorescent luminescent materials contained in noble metals, the singlet (25%) and triplet (75%) excitons are comprehensively utilized through Spin Orbit Coupling (SOC) between the noble metals and ligands of the second generation OLED, the IQE of the second generation OLED can reach 100%, however, the phosphorescent luminescent materials still have the problems that metals such as Ir (III), pt (II) and Os (II) are high in price, the efficiency of the OLED based on phosphorescent luminescent materials is severely rolled down under high current, and the like. In recent years, by designing a Thermally Activated Delayed Fluorescence (TADF) material with a small energy level difference (ΔeST) between the synthetic singlet state (SI) and triplet state (Tl) so that triplet (75%) excitons can cross to the Sl state through the reverse intersystem to re-emit fluorescence, such TADF material can simultaneously utilize singlet excitons with a probability of 25% generation and triplet excitons with a probability of 75% generation to obtain high light-emitting efficiency, and the IQE thereof can be as high as 100%, which is promising as a next-generation OLED light-emitting material. Currently, blue and green OLED phosphors have high efficiency, but the small overlap between HOMO and LUMO reduces the vibrator intensity and the radiation decay rate (kr), generally resulting in reduced luminous efficiency. Thus, highly efficient red TADF materials with Electroluminescent (EL) peaks exceeding 600nm are very lacking.
Although some red light TADF materials have been reported and applied to OLED, the reported TADF materials generally have the problems of long synthesis steps, low preparation efficiency, difficult mass preparation and the like, and the electron-withdrawing fragments of the molecules are very few, mainly concentrated on cyano groups, carbonyl groups, sulfone (sulfoxide) groups and the like.
Disclosure of Invention
Based on the current situation that the efficiency of the red light OLED device is generally lower than that of blue light and green light, the invention provides a red light luminescent material, a preparation method and application thereof, and the invention introduces a phthalimide structure as a receptor, promotes the anti-gap crossing by reducing the fatin EST, enhances the electron donating ability of a donor, successfully prepares the red light TADF material with the fatin EST less than 0.05eV, and is beneficial to improving the efficiency of the red light OLED device.
In order to achieve the above purpose, the present invention provides the following technical solutions:
one of the technical schemes of the invention is as follows:
a red light emitting material characterized by the following structural formula:
Or (b)。
The red light luminescent material has both thermal activation delayed fluorescence effect and aggregation induction effect.
The second technical scheme of the invention is as follows:
the invention also provides a preparation method of the red light luminescent material, when the structural formula isIn the process, AI-1DPACz is marked, and the preparation method comprises the following steps:
Mixing a compound C1, aniline and glacial acetic acid (CH3 COOH), heating and refluxing (Reflux) for reaction, cooling, placing in an environment at 0 ℃ to precipitate a white solid, filtering to obtain a first crude product, washing with water (for removing residual glacial acetic acid) to obtain white crystals, wherein the white crystals are a compound C3, mixing the compound C3, the compound C4 and cesium carbonate (CS2CO3), adding Dimethylformamide (DMF), heating to 65 ℃ for reaction for 12 hours, cooling, adding water and dichloromethane for extraction, drying, filtering and distilling an extracted organic phase to obtain a second crude product, and purifying the second crude product by column chromatography to obtain AI-1DPACz;
When the structure isIn the process, AI-2DPACz is prepared by the following steps:
Mixing a compound C5, aniline and glacial acetic acid, heating and refluxing for reaction, cooling to room temperature, placing in an environment of 0 ℃ to precipitate a white solid, filtering to obtain a first crude product, washing with water (for removing residual glacial acetic acid) to obtain white crystals, mixing the compound C6, the compound C4 and CS2CO3, adding DMF (dimethyl formamide), heating to 65 ℃ for reaction for 12 hours, cooling, adding water and dichloromethane for extraction, drying, filtering and distilling an extracted organic phase to obtain a second crude product, and purifying the second crude product by column chromatography to obtain AI-2DPACz;
the structural formula of the compound C1 isThe structural formula of the compound C3 isThe structural formula of the compound C4 isThe structural formula of the compound C5 isThe structural formula of the compound C6 is。
Preferably, the temperature of the heating reflux reaction is 120 ℃ and the time is 4 hours.
Preferably, the mass volume ratio of the compound C1 to the aniline to the glacial acetic acid is 5g to 3.3mL to 100mL;
the mass ratio of the compound C3 to the compound C4 to the CS2CO3 is 0.5:1.09: 0.6881;
The mass volume ratio of the compound C5 to the aniline to the glacial acetic acid is 6g to 3.56mL to 100mL;
The mass ratio of the compound C6 to the compound C4 to the CS2CO3 is 0.5:2.03:1.32.
Preferably, the volume ratio of water to dichloromethane is 7:1.
Preferably, the extracted organic phases are all dried with anhydrous sodium sulfate.
More preferably, when the red light emitting material is AI-1DPACz, the synthetic route is as follows:
Adding 5g of a compound C1, 3.3mL of aniline (namely C2) and 100mL of glacial acetic acid into a 250mL round bottom flask in sequence, heating and refluxing for reaction for 4 hours at 120 ℃, cooling to room temperature, placing the mixture in a 0 ℃ environment to separate out white solid, filtering to obtain a first crude product, washing with water to remove residual glacial acetic acid, obtaining white crystals, wherein the white crystals are the compound C3, taking the 100mL round bottom flask, carrying out anhydrous and anaerobic treatment, weighing 500mg of the compound C3, 1.09g of the compound C4 and 688.1mg of CS2CO3 into the round bottom flask in sequence, adding 30mL of DMF, heating to 65 ℃ for reaction for 12 hours, cooling to room temperature, adding water and dichloromethane for extraction, drying and filtering the extracted organic phase with anhydrous sodium sulfate, then distilling to remove an organic liquid phase, and purifying the second crude product by column chromatography to obtain AI-1DPACz;
when the red light emitting material is AI-2DPACz, the synthetic route is as follows:
the preparation method of AI-2DPACz comprises the steps of sequentially adding 6g of compound C5, 3.56 mL aniline (namely C2) and 100mL glacial acetic acid into a 250mL round bottom flask, heating and refluxing for 4 hours at 120 ℃, cooling to room temperature, standing in the environment at 0 ℃ to separate out white solid, filtering to obtain a first crude product, washing with water to remove residual glacial acetic acid, obtaining white crystals, wherein the white crystals are compound C6, taking the 250mL round bottom flask, carrying out anhydrous and anaerobic treatment, weighing 500mg of compound C6, 2.03g of compound C4 and 1.32g of CS2CO3 into the round bottom flask, adding 100mL of DMF, heating to 65 ℃ for reaction for 12 hours, cooling to room temperature, adding water and dichloromethane for extraction, drying the extracted organic phase with anhydrous sodium sulfate, filtering, then distilling off the organic liquid phase to obtain a second crude product, and purifying the second crude product by column chromatography to obtain AI-2DPACz.
The third technical scheme of the invention:
The invention also provides application of the red light luminescent material in preparing a red light Organic Light Emitting Diode (OLED) device.
The technical scheme of the invention is as follows:
The invention also provides application of the red light luminescent material in preparing a red heat activated delayed fluorescence material (TADF).
Compared with the prior art, the invention has the following advantages and technical effects:
according to the invention, phthalimide is used as an acceptor, N, N ', N' -tetraphenyl-9H-carbazole-2, 7-diamine is used as a donor, and luminescent molecules (AI-1 DPACz and AI-2 DPACz) with an EST <0.05eV and an aggregation induction effect are obtained, so that the efficient red TADF material with an Electroluminescent (EL) peak value exceeding 600nm is successfully prepared, and is one way for effectively improving the efficiency of a red OLED device.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:
FIG. 1 is a1 H NMR spectrum of AI-1 DPACz;
FIG. 2 is a13 C NMR spectrum of AI-1 DPACz;
FIG. 3 is a1 H NMR spectrum of AI-2 DPACz;
FIG. 4 is a13 C NMR spectrum of AI-2 DPACz;
FIG. 5 is an absorption and emission spectrum of AI-1DPACz and AI-2DPACz, where the abscissa is wavelength, the left ordinate is absorption intensity, and the right ordinate is luminous intensity;
FIG. 6 is a fluorescence spectrum of AI-1DPACz at different Ether levels (0 vol% -99 vol%) in different THF/Ether mixtures;
FIG. 7 is an AIE curve of AI-1DPACz at an emission wavelength of 688 nm;
FIG. 8 is a fluorescence spectrum of AI-2DPACz at different Ether levels (0 vol% -99 vol%) in different THF/Ether mixtures;
FIG. 9 is an AIE curve of AI-2DPACz at an emission wavelength of 724 nm.
Detailed Description
Various exemplary embodiments of the invention will now be described in detail, which should not be considered as limiting the invention, but rather as more detailed descriptions of certain aspects, features and embodiments of the invention.
It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In addition, for numerical ranges in this disclosure, it is understood that each intermediate value between the upper and lower limits of the ranges is also specifically disclosed. Every smaller range between any stated value or stated range, and any other stated value or intermediate value within the stated range, is also encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the invention described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from consideration of the specification of the present invention. The specification and examples of the present invention are exemplary only.
As used herein, the terms "comprising," "including," "having," "containing," and the like are intended to be inclusive and mean an inclusion, but not limited to.
The room temperature in the present invention is 25.+ -. 2 ℃ unless otherwise specified.
The raw materials used in the examples of the present invention are all commercially available.
The technical scheme of the invention is further described by the following examples.
Example 1 AI-1 preparation of 1DPACz
The synthetic route is as follows:
The preparation method comprises sequentially adding 5g of compound C1, 3.3mL of aniline (namely C2) and 100mL of glacial acetic acid into a 250mL round bottom flask, heating and refluxing at 120deg.C for 4 hours, cooling to room temperature, standing in 0 ℃ to separate out white solid, filtering to obtain a first crude product, washing with water to remove residual glacial acetic acid to obtain white crystal, wherein the white crystal is compound C3, the yield is 98%, and the test result of the compound C3 is as follows ：1H NMR (500 MHz, CDCl3, δ ppm) 7.96 (dd,J= 8.0, 4.5 Hz, 1H), 7.63 (d,J= 6.5 Hz, 1H), 7.53-7.39 (m, 6H).
Taking a 100mL round bottom flask for anhydrous and anaerobic treatment, weighing 500mg of compound C3, 1.09g of compound C4 and 688.1mg of CS2CO3, sequentially adding 30mL of DMF into the round bottom flask, heating to 65 ℃ for reaction for 12 hours, cooling to room temperature, adding water and dichloromethane (v/v=7:1) for extraction, drying an extracted organic phase by using anhydrous sodium sulfate, filtering, then distilling to remove an organic liquid phase to obtain a second crude product, purifying the second crude product by using column chromatography to obtain 749mg of orange red powder, namely final product AI-1DPACz, wherein the yield is 50%, and the1 H NMR spectrum of AI-1DPACz is shown in FIG. 1, and the13 C NMR spectrum is shown in FIG. 2.
Example 2 AI-2 preparation of 2DPACz
The synthetic route is as follows:
The preparation method comprises sequentially adding 6g of compound C5, 3.56 mL aniline (C2) and 100 mL glacial acetic acid into 250mL round bottom flask, heating and refluxing at 120deg.C for 4 hr, cooling to room temperature, standing in 0 deg.C environment to separate out white solid, filtering to obtain first crude product, washing with water to remove residual glacial acetic acid to obtain white crystal which is compound C6 with yield of 98%, and testing compound C6 as follows ：1H NMR (500MHz, CDC13) δ7.76 (t,J=7.5Hz, 2H), 7.55-7.47 (m, 2H), 7.46-7.38 (m, 3H).
Taking a 250 mL round bottom flask for anhydrous and anaerobic treatment, weighing 500mg of a compound C6, 2.03g of a compound C4 and 1.32g of CS2CO3, sequentially adding 100mL of DMF into the round bottom flask, heating to 65 ℃ for reaction for 12 hours, cooling to room temperature, adding water and methylene dichloride for extraction, drying an extracted organic phase with anhydrous sodium sulfate, filtering, distilling to remove an organic liquid phase to obtain a second crude product, purifying the second crude product by column chromatography to obtain 707mg of red powder, namely AI-2DPACz, wherein the yield is 30%, and a1 H NMR spectrum of AI-2DPACz is shown in FIG. 3 and a13 C NMR spectrum is shown in FIG. 4.
The absorption and emission spectra of AI-1DPACz and AI-2DPACz are shown in FIG. 5, which shows that AI-1DPACz has an emission wavelength of 254 nm and AI-2DPACz has an emission wavelength of 694nm.
The fluorescence spectra of AI-1DPACz under different Ether contents (0 vol% -99 vol%) in different THF/Ether (tetrahydrofuran/Ether) mixtures are shown in FIG. 6, and the AIE curve with the emission wavelength of 688nm is shown in FIG. 7, so that the material has aggregation-induced emission property.
The fluorescence spectra of AI-2DPACz under different diethyl Ether contents (0 vol% -99 vol%) in different THF/Ether mixtures are shown in FIG. 8, and the AIE curve with emission wavelength of 724nm is shown in FIG. 9, so that the material has aggregation-induced emission property.
In conclusion, the red light TADF material with EST <0.05eV is prepared by taking the phthalimide structure (C3) as an acceptor and adopting N, N, N ', N' -tetraphenyl-9H-carbazole-2, 7-diamine (C4) as a donor for the first time, and is one way for effectively improving the efficiency of a red light OLED device.
The present application is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present application are intended to be included in the scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.