CN116731047B

CN116731047B - Thermally activated delayed fluorescent materials based on carbene-gold (I)-arylamine derivatives and preparation methods and applications thereof

Info

Publication number: CN116731047B
Application number: CN202310557779.6A
Authority: CN
Inventors: 龚少龙; 张贺
Original assignee: Shenzhen Research Institute of Wuhan University
Current assignee: Shenzhen Research Institute of Wuhan University
Priority date: 2023-05-17
Filing date: 2023-05-17
Publication date: 2025-09-30
Anticipated expiration: 2043-05-17
Also published as: CN116731047A

Abstract

The invention discloses a thermal activation delay fluorescent material containing gold (I), and a preparation method and application thereof. The invention uses carbene (Carbene, C) with electron pulling effect as electron acceptor, uses aromatic amine derivative (amide, A) with electron donating effect as electron donor, and uses gold atom as bridge to connect. Forming a CMA-type charge transfer compound. The linear bidentate gold (I) complex avoids excited state recombination caused by ginger-Taylor effect, thereby realizing photoluminescence quantum yield close to 1, and the material has simple synthesis method, easy adjustment of light color and large-scale preparation. The gold (I) -based thermally activated delayed fluorescent material has excellent electrical properties and rapid reverse intersystem jump rate, and the organic electroluminescent device using the gold (I) -based thermally activated delayed fluorescent material as a luminescent layer material has the advantages of low driving voltage, low roll-off efficiency, long service life and high efficiency.

Description

Thermal activation delayed fluorescent material based on carbene-gold (I) -aromatic amine derivative, and preparation method and application thereof

Technical Field

The invention belongs to the field of organic photoelectric material preparation and electroluminescent devices, and particularly relates to a full-color system thermal activation delay fluorescent material based on a carbene-gold (I) -arylamine derivative, and a preparation method and application thereof.

Background

Since Deng Qingyun doctor in 1987 first applied the fluorescent metal complex 8-hydroxyquinoline aluminum to the organic electroluminescent field, organic Light Emitting Diodes (OLEDs) have received extensive academic and industrial attention. However, the upper limit of the internal quantum efficiency of the conventional fluorescent OLED is 25% due to the limitation of the fluorescent property. In order to achieve 100% internal quantum efficiency, phosphorescent complexes of heavy metals such as Ru (II), ir (III), os (II) and Pt (II) have been developed, and in particular, ir (III) complexes are widely used in OLED industry due to their high luminous efficiency and high stability. However, the abundance of precious metals on earth is extremely low, and high cost and potential environmental pollution are detrimental to sustainable development. At present, a Thermal Activation Delayed Fluorescence (TADF) material is a very promising material and has potential practical application value in the OLED field. Most TADF materials reported to date are organic compounds with a small SOC between the S ₁ and T ₁ states, resulting in a relatively long delayed fluorescence lifetime (typically >5 μs), resulting in a severe degradation of the device efficiency at high brightness. So far, the variety of metal complexes having TADF properties is still very limited.

Gold has a relatively high abundance in the crust of the earth compared to the noble metals described above. And compared with metals such as copper, silver and the like, the coordination bond formed by gold has higher stability and is an attractive candidate material for developing the OLED. However, au (III) complexes have a slight metal contribution and often exhibit ligand-centered emission. The radiation attenuation rate is small, the service life is long, the OLED has serious efficiency roll-off, and only a few devices can realize good EQE and low efficiency roll-off at the same time. Recently, carbene-metal-aromatic amine derivatives having a bidentate structure have received a great deal of attention for a delayed lifetime of sub-microsecond due to the highly efficient TADF, but the synthesis of materials is relatively difficult, and the variety is still being further developed.

Disclosure of Invention

In view of the defects in the prior art, and expanding the variety of the existing carbene-metal-aromatic amine derivatives, the problems of long service life of the pure organic heat-activated delayed fluorescent material, serious device efficiency roll-off and high cost of the phosphorescent heavy metal complex are solved. The invention provides a thermal activation delay fluorescent material of a carbene-gold (I) -aromatic amine derivative, and a preparation method and application thereof.

The technical scheme of the invention is as follows:

the structural general formula of the thermal activation delayed fluorescence material based on the carbene-gold (I) -aromatic amine derivative is shown as formula A, B:

wherein R is a protecting group may be selected from, but is not limited to, one of the following structures:

R ₁-R₈ is at least one, or a combination of different numbers, R ₁-R₈ is the same or different and is independently selected from hydrogen, halogen, trifluoromethyl, cyano, C ₁-C₄ alkyl, C ₁-C₆ alkoxy, substituted or unsubstituted C ₆-C₃₀ aryl, substituted or unsubstituted C ₃-C₃₀ heteroaryl;

Or adjacent two of R ₁-R₈ are connected with each other to form aryl of C ₆-C₃₀ and heteroaryl of C ₅-C₃₀.

The substituted C ₆-C₃₀ aryl and substituted C ₅-C₃₀ heteroaryl contain 1-8 substituents which are independently selected from any one of hydrogen, halogen, cyano, C ₁-C₄ alkyl, C ₆-C₃₀ aryl, C ₅-C₃₀ heteroaryl and substituted or unsubstituted diarylamino.

By adjusting the electron donating ability of the donor, emission from blue to red light can be achieved.

The compound has the following specific structure:

the invention provides a preparation method of a thermal activation delay fluorescent material based on a carbene-gold (I) -aromatic amine derivative, which comprises the following synthetic route:

the preparation method comprises the following steps:

Under the anhydrous and anaerobic condition, the carbene complex intermediate, the arylamine derivative and the alkali are added into the aprotic organic solvent for reaction. Purifying to obtain the heat-activated delayed fluorescence material based on the carbene-gold (I) -aromatic amine derivative.

The base used is organic or inorganic base such as sodium hydride, potassium hydride, sodium tert-butoxide, potassium carbonate, cesium carbonate, etc.

Preferably:

The base used is sodium hydride.

The nucleophilic substitution reaction is carried out at room temperature for 0.5-48h.

Preferably:

the reaction time was 2h.

The nucleophilic substitution reaction is carried out in tetrahydrofuran, 1, 4-dioxane, acetone, and other polar aprotic solvents.

Preferably:

the selected solvents are tetrahydrofuran and acetone.

The purification steps selected include recrystallization and sublimation.

The invention also provides an application of the organic thermal activation delay fluorescent material based on the carbene-gold (I) -aromatic amine derivative in preparing an organic electroluminescent device.

Preferably:

as a luminescent material for electroluminescent devices.

The invention also provides an organic electroluminescent device, and a luminescent layer of the organic electroluminescent device comprises the thermal activation delay fluorescent material based on the carbene-gold (I) -aromatic amine derivative.

The invention has the following advantages:

(1) The aromatic amine derivative with strong electron donating property is used as an electron donor, the carbene with pi-electron withdrawing property is used as an electron acceptor, the complex excited state has obvious LLCT property, and the high-efficiency TADF is easy to obtain.

(2) The light color can be adjusted by using arylamine derivatives with different electron donating capacities, so that the full-color efficient OLED can be realized.

(3) The heavy atomic effect provided by gold atoms can obviously improve the reverse intersystem crossing rate, so that the service life of the complex is less than 1 mu s, the accumulation of triplet excitons is reduced, and the device efficiency roll-off can be reduced when the complex is applied to a device.

Drawings

FIG. 1 is a graph showing the UV-visible absorption spectrum of the TADF fluorescent material 27 of the present invention in toluene solution.

FIG. 2 is a graph showing fluorescence spectra of the TADF fluorescent material 27 of the present invention in toluene solution.

Fig. 3 is a graph of fluorescence spectrum of the TADF fluorescent material 27 of the present invention doped with 10% in the host material mCP.

Fig. 4 is a graph of the transient photo-induced spectral decay of TADF phosphor 27 of the present invention in toluene solution.

Fig. 5 is a graph of the transient light induced spectral decay of the TADF phosphor material 27 of the present invention doped at 10% in the host material mCP.

Fig. 6 is a schematic structural diagram of a spin-on organic electroluminescent device according to the present invention.

Detailed Description

The invention provides a thermal activation delay fluorescent material based on a carbene-gold (I) -aromatic amine derivative, a preparation method thereof and application thereof in an electroluminescent device, and aims to make the purposes, technical schemes and effects of the invention clearer and more definite. The technical solution of the present invention is further illustrated by the following examples, it being understood that the specific examples described herein are only for the purpose of illustrating the present invention and are not to be construed as limiting the present invention.

The raw materials and reagents used in the present invention are all commercially available.

The following is a detailed description of specific examples.

EXAMPLE 1 preparation of several important intermediates

Preparation of intermediate 1

The synthetic route is as follows:

9-Anthramethylene-formaldehyde (20 mmol,4.1 g), 2-methyl-3-butyn-2-amine (30 mmol,2.5 g) was dissolved in 100mL of toluene and refluxed for 24 hours. Cooled to room temperature, toluene was removed by distillation under reduced pressure, and purified by column chromatography to give 2.6g of pale yellow solid in 48% yield.

Preparation of intermediate 2

The synthetic route is as follows:

Intermediate 1 (5.4 g,20 mmol), 1-bromoadamantane (4.7 g,22 mmol), 2, 6-di-tert-butyl-4-methylpyridine (0.4 g,2 mmol) and silver trifluoromethane sulfonate (6.2 g,24 mmol) were taken in a 250mL round bottom flask, added with 100mL of n-hexane and reacted at room temperature in the absence of light for 24h. After the reaction was completed, n-hexane was removed by spinning, and a dichloromethane dissolution product was added. The filtrate was spun to a small amount, recrystallized by adding n-hexane, the product was precipitated, suction-filtered and dried to give 4.0g of a white solid with a yield of 37%.

Preparation of intermediate 3

The synthetic route is as follows:

intermediate 2 (2.2 g,4 mmol), gold (I) chloride (dimethyl sulfide) (1.18 g,4 mmol) was taken and dissolved in 20mL of ultra-dry tetrahydrofuran, cooled at 0℃for 5 minutes, followed by addition of potassium bis (trimethylsilyl) amide (1 mol/L in THF,8 mL), reacted overnight at 0℃and recrystallized from tetrahydrofuran/n-hexane to afford 382mg of pale yellow-green solid in 15% yield.

Preparation of intermediate 4

The synthetic route is as follows:

Intermediate 1 (2.7 g,10 mmol) was taken in a 100mL pressure-resistant tube, 30mL acetonitrile was added for dissolution, then 2-bromopropane (6.2 g,50 mmol) was added for reaction at 90 ℃ for 48 hours, the reaction was completed, cooled to room temperature, the solvent was swirled to a small amount, the diethyl ether product was added for precipitation, and suction filtration and drying were carried out to obtain 2.4g of white solid with a yield of 62%.

Preparation of intermediate 5

The synthetic route is as follows:

Intermediate 4 (1.977 g,5 mmol), gold (dimethyl sulfide) (1.48 g,5 mmol) was taken, dissolved in 20mL ultra-dry tetrahydrofuran, cooled at 0℃for 5min, followed by addition of potassium bis (trimethylsilyl) amide (1 mol/L in THF,10 mL), reacted overnight at 0℃and recrystallized from tetrahydrofuran/n-hexane to give 464mg of a pale yellow-green solid in 17% yield.

Preparation of intermediate 6

The synthetic route is as follows:

3-bromocarbazole (1.2 g,5 mmol) was taken, cuprous cyanide (4478 mg,5 mmol) was dissolved in 10mL of N-methylpyrrolidone under argon protection, reacted overnight at 170℃until the reaction was completed, cooled to room temperature, ferric (III) chloride hydrochloric acid solution was added to the system, the remaining cuprous cyanide was removed, washed with water, extracted with chloroform, and column chromatography gave 0.7g of white solid with a yield of 72%.

Example 2:

Synthesis of Compound 2

The synthetic route is as follows:

Intermediate 6 (192 mg,1 mmol) synthesized in example 1 was taken and dissolved in 5mL of super-dry tetrahydrofuran, reacted at room temperature for 5 minutes, and intermediate 3 (618 mg,1 mmol) synthesized in example 1 was taken and dissolved in 5mL of super-dry tetrahydrofuran, reacted at room temperature for 2 hours, after the reaction was completed, filtered with celite, recrystallized from methylene chloride/n-hexane to give 492mg of the product in yield 62％.HRMS(ESI)m/z calcd for C₄₃H₃₉AuN₃ ⁺(M)⁺794.28040,found 794.28011.

Example 3:

Synthesis of Compound 1

The synthetic route is as follows:

Carbazole (167 mg,1 mmol) was taken and dissolved in 5mL of ultra-dry tetrahydrofuran, sodium cyanide (60%dispersion in mineral oil,60mg,1.5mmol) was reacted at room temperature for 5 minutes, and intermediate 3 (428 mg,1 mmol) synthesized in example 1 was taken and dissolved in 5mL of ultra-dry tetrahydrofuran, reacted at room temperature for 5 hours, after the reaction was completed, filtered with celite, recrystallized from methylene chloride/n-hexane to give 422mg of product in yield 55％.HRMS(ESI)m/z calcd for C₄₃H₃₉AuN₃ ⁺(M)⁺769.28525,found 769.28502.

Example 4:

synthesis of Compound 27

The synthetic route is as follows:

3, 6-Di-t-butylcarbazole (279 mg,1 mmol) was taken and dissolved in 5mL of ultra-dry tetrahydrofuran, and reacted at room temperature for 5 minutes, and intermediate 3 (618 mg,1 mmol) synthesized in example 1 was taken and dissolved in 5mL of ultra-dry tetrahydrofuran, reacted at room temperature for 5 hours, and after the reaction was completed, filtered with celite, recrystallized from methylene chloride/n-hexane to give 616mg of the product in yield 70％.HRMS(ESI)m/z calcd for C₄₃H₃₉AuN₃ ⁺(M)⁺881.41035,found 881.41022.

Example 5:

Synthesis of Compound 35

The synthetic route is as follows:

Carbazole (167 mg,1 mmol) was taken and dissolved in 5mL of ultra-dry tetrahydrofuran, sodium cyanide (60%dispersion in mineral oil,60mg,1.5mmol) was reacted at room temperature for 5 minutes, and intermediate 5 (545 mg,1 mmol) synthesized in example 1 was taken and dissolved in 5mL of ultra-dry tetrahydrofuran, reacted at room temperature for 5 hours, after the reaction was completed, filtered with celite, recrystallized from methylene chloride/n-hexane to give 291mg of product in yield 43％.HRMS(ESI)m/z calcd for C₄₃H₃₉AuN₃ ⁺(M)⁺677.22255,found 677.22213.

Example 6:

Synthesis of Compound 61

The synthetic route is as follows:

3, 6-Di-t-butylcarbazole (279 mg,1 mmol) was taken and dissolved in 5mL of ultra-dry tetrahydrofuran, and reacted at room temperature for 5 minutes, and intermediate 3 (545 mg,1 mmol) synthesized in example 1 was taken and dissolved in 5mL of ultra-dry tetrahydrofuran, reacted at room temperature for 5 hours, and after the reaction was completed, filtered with celite, recrystallized from methylene chloride/n-hexane to give 457mg of the product in yield 58％.HRMS(ESI)m/z calcd for C₄₃H₃₉AuN₃ ⁺(M)⁺789.34775,found 789.34742.

Test example 1:

ultraviolet-visible absorption spectrum of test compound 27 in solution.

5ML of 10 ^-5 M toluene solution of compound 27 was prepared, and an ultraviolet-visible absorption spectrum was measured at room temperature, and the measurement result is shown in FIG. 1, and it was found that the absorption of the complex at 380-500nm in the long wavelength region was a charge transition from carbazole ligand to carbene ligand.

Test example 2:

fluorescence spectrum of compound 27 in solution.

5ML of 10 ^-4 M toluene solution of compound 27 was prepared, fluorescence spectrum measurement was performed at room temperature, excitation wavelength was 400nm, and the test result is shown in FIG. 2, and it was found that the compound exhibited a remarkable charge transfer state broad-peak emission property in toluene solution, and its emission peak was 585nm.

Test example 3:

Fluorescence spectrum of test compound 27 in doped film.

The compound 27 was doped in the host material mCP at 10%, and the excitation wavelength of the fluorescence spectrum was measured at room temperature and was 330nm, and the test result is shown in fig. 3, and it was found that the compound host material mCP exhibited a significant charge transfer state broad-peak emission property, and the emission peak was 520nm.

Test example 4:

Transient light-induced spectral decay curve for the solution state of test compound 27.

5ML of 10 ^-4 M toluene solution of compound 27 was prepared, and a transient photoinduced spectral decay curve was tested at room temperature, the excitation wavelength was 373.2nm, and the test results are shown in FIG. 4, which shows that the compound shows an extremely short delayed fluorescence lifetime in a deoxygenated toluene solution, indicating that triplet excitons participate in the luminescence process, and the lifetime is 101ns.

Test example 5:

Transient light induced spectral decay curve of test compound 27 in doped films.

The compound 27 is doped into a main material mCP at 10%, a transient photoinduced spectrum decay curve graph is tested under the condition of room temperature, the excitation wavelength is 373.2nm, the test result is shown in fig. 5, and the compound shows extremely short delayed fluorescence lifetime in the main material mCP, which indicates that triplet state excitons participate in the luminescence process, and the lifetime is 532ns.

The test results show that the metal complex based on the carbene-gold (I) -arylamine derivative has remarkable thermal activation delayed fluorescence characteristic, has shorter delayed fluorescence life and faster reverse intersystem crossing process compared with the traditional pure organic thermal activation delayed fluorescence material.

In summary, the invention provides a thermally activated delayed fluorescent material based on a carbene-gold (I) -arylamine derivative, the heavy atom effect of gold atoms remarkably increases the orbital spin coupling between singlet states in an excited state, greatly increases the reverse intersystem crossing rate of triplet state excitons, shortens the delayed fluorescence lifetime, thereby reducing the quenching of triplet state excitons under high brightness, being beneficial to reducing the device efficiency roll-off, and further, the light color is easily regulated by using donors with different electron donating capacities, thereby realizing full-color OLED.

It should be understood that the above examples are not limiting embodiments of the present invention, and that various modifications can be made by those skilled in the art based on the above description, and that all such modifications and changes are deemed to fall within the scope of the appended claims.

Claims

1. The thermal activation delay fluorescent material based on the carbene-gold (I) -aromatic amine derivative is characterized by having a structural general formula shown in a formula A or a formula B:

Wherein R is a protecting group, R ₁-R₈ are the same or different and are each independently selected from hydrogen, halogen, trifluoromethyl, cyano, alkyl of C ₁-C₄, alkoxy of C ₁-C₆, substituted or unsubstituted C ₆-C₃₀ aryl, substituted or unsubstituted C ₅-C₃₀ heteroaryl;

Or adjacent two of R ₁-R₈ are connected with each other to form aryl of C ₆-C₃₀ and heteroaryl of C ₅-C₃₀;

The substituted C ₆-C₃₀ aryl and substituted C ₅-C₃₀ heteroaryl contain 1-8 substituents which are independently selected from any one of hydrogen, halogen, cyano, C ₁-C₄ alkyl, C ₆-C₃₀ aryl, C ₅-C₃₀ heteroaryl and substituted or unsubstituted diarylamino;

the protecting group is one of the following structures:

2. The heat-activated delayed fluorescence material based on carbene-gold (I) -arylamine derivative according to claim 1, characterized by having the following specific structure:

3. a method for preparing a thermally activated delayed fluorescence material based on a carbene-gold (I) -arylamine derivative according to any one of claims 1 to 2, characterized by the following synthetic route:

the preparation method comprises the following steps:

adding the carbene intermediate and the aromatic amine derivative into an organic solvent, and carrying out nucleophilic substitution reaction under the catalysis of alkali to obtain the thermal activation delay fluorescent material.

4. A method for preparing a thermally activated delayed fluorescence material based on a carbene-gold (I) -arylamine derivative according to claim 3, characterized in that the base used is sodium hydride, potassium hydride, sodium tert-butoxide, potassium carbonate, cesium carbonate.

5. The method for preparing a heat-activated delayed fluorescence material based on a carbene-gold (I) -arylamine derivative according to claim 3, wherein said nucleophilic substitution reaction is performed at room temperature for 0.5-48 hours.

6. The method for preparing a heat-activated delayed fluorescence material based on a carbene-gold (I) -arylamine derivative according to claim 3, wherein the nucleophilic substitution reaction is performed in tetrahydrofuran, 1, 4-dioxane, and acetone.

7. A method for preparing a heat-activated delayed fluorescence material based on a carbene-gold (I) -arylamine derivative as defined in claim 3, further comprising the step of purifying the synthesized heat-activated delayed fluorescence material, and recrystallizing and sublimating.

8. Use of a thermally activated delayed fluorescence material based on a carbene-gold (I) -arylamine derivative according to any of claims 1-2, as a luminescent material for electroluminescent devices.

9. An organic electroluminescent device, characterized in that the luminescent layer of the organic electroluminescent device comprises a thermally activated delayed fluorescence material based on a carbene-gold (I) -arylamine derivative according to claim 8.