阅读说明：本技术 一种含三蝶烯基团的热活化延迟荧光材料及其制备方法和应用 (Thermal activation delayed fluorescent material containing triptycene group and preparation method and application thereof ) 是由 卢灿忠 陈旭林 景艳云 于 2020-08-05 设计创作，主要内容包括：本发明公开一种含三蝶烯基团的热活化延迟荧光材料及其制备方法和应用。该材料主要特征是结构中含有三蝶烯基团,三蝶烯基团的存在提高了此类材料的热稳定性和成膜性,缩短了延迟荧光寿命。此类材料制备方法简单,光致发光量子效率高。将此类材料作为发光层中的客体分子应用于电致发光器件中,制备了具有低驱动电压、高效率、高亮度及低效率滚降的有机发光二极管。(The invention discloses a thermal activation delayed fluorescence material containing a triptycene group and a preparation method and application thereof. The material is mainly characterized in that the structure of the material contains a triptycenyl group, and the existence of the triptycenyl group improves the thermal stability and the film forming property of the material and shortens the life of delayed fluorescence. The material has simple preparation method and high photoluminescence quantum efficiency. The material is used as a guest molecule in a luminescent layer and applied to an electroluminescent device to prepare the organic light-emitting diode with low driving voltage, high efficiency, high brightness and low efficiency roll-off.)

1. A thermally activated delayed fluorescence material containing a triptycenyl group, characterized by having any one of the following chemical structures (1) to (3):

wherein the substituent D is any one of aromatic amine groups represented by the following formulas (1) to (5):

wherein R is a straight chain or branched chain alkyl group with the carbon atom number of 1-16.

2. The preparation method of the thermal activation delayed fluorescence material containing the triptycenyl group as claimed in claim 1, characterized by comprising the following steps:

(1) preparing an intermediate of any one of the following formulas a-r:

(2) adding any intermediate, the aromatic amine compound, the alkali and the catalyst in the step (1) into a dry reaction bottle, performing air pumping with inert gas for three times, then injecting an organic solvent, uniformly stirring, heating for reflux reaction, cooling to room temperature after the reaction is finished, adding distilled water, extracting, drying, filtering, performing rotary evaporation to remove the organic solvent to obtain a crude product, and performing column chromatography separation to obtain a pure target compound.

3. The method for preparing the thermal activation delayed fluorescence material containing the triptycenyl group as claimed in claim 1, wherein the step (1) is to prepare any one of intermediates having the structure of formula a-r, and the intermediate is prepared by the following steps:

adding raw materials of triptycene and aluminum chloride into carbon disulfide in the air, cooling a system to 0 ℃, slowly adding 4-bromo-benzoyl chloride, gradually heating the system to room temperature after adding the 4-bromo-benzoyl chloride, and then heating the system to 50-70 ℃ for reflux reaction for 12 hours; after the reaction is finished, adding crushed ice into the system to terminate the reaction, then removing the organic solvent through extraction, drying, filtration and rotary evaporation to obtain a crude product, and separating through column chromatography to obtain a target intermediate;

the dosage of the aluminum chloride is 1.3 times of that of the triptycene; the dosage of the 4-bromo-benzoyl chloride is the same as that of triptycene.

4. The method for preparing the thermal activation delayed fluorescence material containing the triptycenyl group as claimed in claim 1, wherein the heating reflux reaction in the step (2) is carried out under the specific reaction conditions:

a. the heating temperature is 90-100 ℃, and the reaction time is 12-48 hours;

b. the alkali is selected from any one of sodium tert-butoxide or cesium carbonate, and the dosage of the alkali is 1.5 to 3 times of that of the intermediate;

c. the catalyst is selected from palladium acetate or tri (tert-butyl) phosphine tetrafluoroborate, and the dosage of the catalyst is 0.09-0.1 time of that of the intermediate;

d. the organic solvent is any one of toluene or N, N-dimethylformamide.

5. The method for preparing the thermal activation delayed fluorescence material containing the triptycenyl group as claimed in claim 1, wherein the aromatic amine compound in the step (2) is any one of the aromatic amine groups shown in the following formula (1) to formula (5), and the amount of the aromatic amine compound is 1.2-4.5 times of the amount of the intermediate;

wherein R is a straight chain or branched chain alkyl group with the carbon atom number of 1-16.

6. Use of any of the thermally activated delayed fluorescence materials containing a triptycenyl group as claimed in claim 1 in an organic electroluminescent diode.

Technical Field

The invention relates to the technical field of luminescent layer materials in organic electroluminescent devices, in particular to a preparation method and application of a thermal activation delayed fluorescent material containing triptycenyl groups.

Background

The organic light emitting diode is expected to be outstanding in the fields of future display and illumination by virtue of the advantages of self-luminescence, low driving voltage, fast response, wide viewing angle, ultra-thin flexibility and the like. The luminescent materials as the core part of the organic light emitting diode are mainly divided into three main categories: fluorescent materials, phosphorescent materials, and thermally activated delayed fluorescence materials. The third generation luminescent material, the thermal activation delayed fluorescence material has smaller energy gap difference (delta E) between singlet state and triplet state due to the existence of_ST) And the lowest triplet excited state intersystem crossing to the lowest singlet excited state can be realized at room temperature, so that the internal quantum efficiency of the prepared organic light-emitting diode reaches 100%. In addition, the thermally activated delayed fluorescence material has the advantages of simple preparation, no use of noble metal, high photoluminescence quantum efficiency and the like, so the thermally activated delayed fluorescence material has great potential in the aspect of preparing efficient, stable and commercially available organic light emitting diodes (1. Hiroki Uoyama et al).Nature2012,492, 234; 2. Takuji Hatakeyama et al.Advanced Materials2016,28, 2777; 3. Xun Tang et al.Nature Materials2020.）。

Currently, researchers have developed many highly efficient thermally activated delayed phosphors and fabricated them into organic light emitting diodes, but most devices exhibit severe efficiency roll-off at high current densities (1. ShuzoHirata et al).Nature Materials2014,14, 330; 2. Nidhi Sharma et al.Chem. Sci.2019,10, 6689). This efficiency roll-off is mainly caused by the long lifetime of the excited state of the light-emitting material, which will initiate the annihilation process of excitons, such as triplet-triplet annihilation, singlet-triplet annihilation, and triplet-polaron annihilation, thereby reducing the exciton concentration and directly leading to a significant reduction in device efficiency. People shorten the thermal activation delay fluorescent materialThe method of excited state lifetime is mainly to further narrow Delta E by molecular design_STAnd the coupling effect of the rotary rail is enhanced, so that a faster reverse system crossing process is realized. However, the excited state lifetime of most thermally activated delayed fluorescent materials designed and synthesized by the method is still longer than 2 microseconds, and therefore, the development of a molecular design strategy capable of effectively shortening the excited state lifetime is an urgent problem to be solved.

In addition, the thermal stability and film-forming quality of the luminescent material are two key factors (Chen-Han Chien et al) for improving the stability and prolonging the service life of the device.Advanced Functional Materials2009,19,560). The high thermal stability of the material prevents decomposition and crystallization of the material during device operation; and the high-quality thin film is beneficial to maintaining the interface between the light-emitting layer and the adjacent functional layer, thereby facilitating the transfer of charges and holes. At present, the method for improving the thermal stability and the film forming quality of the thermal activation delayed fluorescence material is mainly to design and synthesize the dendritic macromolecules and the polymers with the thermal activation delayed fluorescence property, but the materials have large molecular weight and are difficult to evaporate in vacuum, so that the challenge is brought to the preparation of more efficient devices by a vacuum evaporation method. Therefore, it is very important to design and synthesize an organic small-molecule thermal-activation delayed fluorescent material with high thermal stability, high film-forming quality and short excited-state lifetime.

Disclosure of Invention

In view of the above-mentioned disadvantages and shortcomings of the prior art, the present invention is directed to a thermally activated delayed fluorescence material containing a triptycenyl group.

The invention also aims to provide a preparation method of the thermal activation delayed fluorescence material containing the triptycenyl group.

The invention also aims to provide the application of the thermal activation delayed fluorescence material containing the triptycenyl group in an organic light-emitting diode.

The invention adopts the following specific technical scheme:

a thermally activated delayed fluorescence material containing a triptycenyl group, characterized by having any one of the following chemical structures (1) to (3):

wherein the substituent D is any one of aromatic amine groups described in the following formula (1) to formula (5):

wherein R is a straight chain or branched chain alkyl group with the carbon atom number of 1-16.

A preparation method of a thermal activation delayed fluorescence material containing a triptycenyl group is characterized by comprising the following steps:

(1) preparing an intermediate of any one of the following formulas a-r:

(2) adding the intermediate, the aromatic amine compound, the alkali and the catalyst in the step (1) into a dry reaction bottle, performing air pumping with inert gas for three times, then injecting an organic solvent, uniformly stirring, heating for reflux reaction, cooling to room temperature after the reaction is finished, adding distilled water, extracting, drying, filtering, removing the organic solvent to obtain a crude product, and performing column chromatography separation to obtain a pure target compound.

The preparation of any intermediate with a structure of formula a-r in step (1) specifically comprises:

adding raw materials triptycene and aluminum chloride into carbon disulfide in the air, cooling a system to 0 ℃, slowly adding 4-bromo-benzoyl chloride, gradually heating the system to room temperature after adding the 4-bromo-benzoyl chloride, and heating the system to 50-70 ℃ for reflux reaction for more than 12 hours; after the reaction is finished, adding crushed ice into the system to terminate the reaction, then removing the organic solvent through extraction, drying, filtration and rotary evaporation to obtain a crude product, and separating through column chromatography to obtain a target intermediate;

the dosage of the aluminum chloride is 1.3 times of that of the triptycene; the dosage of the 4-bromo-benzoyl chloride is the same as that of triptycene.

The heating reflux reaction in the step (2) is carried out under the specific reaction conditions:

a. the heating temperature is 90-100 ℃, and the reaction time is 12-48 hours;

b. the alkali is selected from any one of sodium tert-butoxide or cesium carbonate, and the dosage of the alkali is 1.5 to 3 times of that of the intermediate;

c. the catalyst is selected from palladium acetate or tri (tert-butyl) phosphine tetrafluoroborate, and the dosage of the catalyst is 0.09-0.1 time of that of the intermediate;

d. the organic solvent is any one of toluene or N, N-dimethylformamide.

Any one of the aromatic amine groups of the aromatic amine compounds in the step (2) and the formulas (1) to (5) is 1.2 to 4.5 times of the dosage of the intermediate;

wherein R is a straight chain or branched chain alkyl group with the carbon atom number of 1-16.

The thermal activation delayed fluorescent material containing the triptycenyl group is applied to an organic light-emitting diode.

Compared with the prior art, the invention has the beneficial effects that:

(1) the novel thermal activation delayed fluorescence material of the invention introduces triptycene group as molecular skeleton, and shortens the service life of the excited state of the material on the basis of not expanding molecular conjugation.

(2) The thermal activation delayed fluorescence material containing the triptycenyl group is an organic micromolecule material, has high thermal stability and good film forming property, and can form a high-quality film by a spin coating method and a vacuum evaporation method.

(3) The thermal activation delayed fluorescence material containing the triptycenyl group is used as a light-emitting layer guest material and applied to an organic light-emitting diode to obtain a good effect, and the range of organic photoelectric materials is widened.

(4) The preparation method of the thermal activation delayed fluorescence material containing the triptycenyl group is simple, and a target product can be obtained through two-step simple reaction.

(5) The thermal activation delayed fluorescence material containing the triptycenyl group can adjust the luminescent color of the material by changing the type of the connected donor, thereby realizing full-spectrum emission.

Drawings

FIG. 1 is a comparison of the molecular structural formulas T1-T17 of some preferred embodiments encompassed by the present invention;

FIG. 2 is a comparison of the crystal structures of compounds T1, T2 and T5;

FIG. 3 is a thermogravimetric plot of compounds T1, T2, T9 and T17;

FIG. 4 is an AFM photograph of thin films of compounds T1, T2, T9 and T17 prepared by spin coating, in which: a is an atomic force microscope photograph of a T1 film, b is an atomic force microscope photograph of a T2 film, c is an atomic force microscope photograph of a T9 film, and d is an atomic force microscope photograph of a T17 film;

FIG. 5 is an atomic force microscope photograph of a doped thin film of compound T1 prepared by vacuum evaporation;

FIG. 6 is a UV-VIS absorption and emission spectra of compounds T1, T2, T9 and T17 in toluene solution;

FIG. 7 is a temperature swing transient lifetime spectrum comparison of doped thin films of compounds T1, T2, T9 and T17;

FIG. 8 is a current density-voltage-luminance curve of an organic light emitting diode comprising Compound T1;

fig. 9 is a luminance-external quantum efficiency-power efficiency-current efficiency curve of an organic light emitting diode comprising compound T1.

Detailed Description

The present invention will be further described with reference to the following examples. It should be noted that: the following examples should not be construed as limiting the scope of the invention. Any modification made on the basis of the invention will not depart from the innovative spirit of the invention.