Patent Application
20240324460
The present invention relates to the technical field of organic luminescent dyes, in particular to a B/N organic electroluminescent material and a preparation method and use thereof.
Organic luminescent dyes have wide application value in electronic devices. For example, in an organic light-emitting device (OLED), carriers, i.e., electrons and holes, are injected respectively by applying a voltage across a cathode (Al) and an anode (ITO), wherein the electrons and holes pass through an electron transport layer (ETL) and a hole transport layer (HTL) respectively to reach a light-emitting layer (EML) containing an organic luminescent dye, and in the light-emitting layer (EML), the electrons and holes recombine to generate excitons for emitting photons outward in a fluorescence or phosphorescence process. OLED technology has the advantages such as wide viewing angle, ultra-thinness, fast response, high luminous efficiency, and flexible display. Furthermore, due to its large-area film-forming and low power consumption properties, it is also an ideal plane light source, which has broad application prospects in the future energy-saving and environment-friendly lighting field.
In recent years, thermally activated delayed fluorescence (TADF) materials have been widely developed and applied in electronic devices due to their effective utilization of triplet excitons. Particularly, in the field of OLED, such dyes can simultaneously use 25% singlet and 75% triplet excitons generated by electro-excitation to obtain high device efficiency. Up to now, the introduction of TADF materials as luminescent dyes in OLEDs can achieve high efficiency, but in most cases, the color purity is very poor, which cannot meet the technical requirements of ultra-high definition full-color display technology (Rec. 2020 standard). Therefore, a novel material system with high efficiency and high color purity needs to be developed urgently. In recent years, although a novel TADF material with multiple resonance effect (MR) has been reported to be capable of achieving emission with high color purity (Adv. Mater., 28, 2777-2781 (2016); Nat. Photonics (2019) DOI: 10.1038/s41566-019-0476-5; Angew. Chem. Int. Ed., 57, 11316-11320 (2018); Adv. Opt. Mater., 1801536 (2019); ACS Appl. Mater. Interfaces 11, 13472-13480 (2019)), the CIE of the green OLED device with the highest quality reported currently is only (0.16, 0.71) (Angew. Chem. Int. Ed., 60, 23142-23147), which is still far below the green standard of Rec. 2020 (the CIE is (0.20, 0.80), where CIEy represents the ratio of green light in luminescence, and the higher the value, the purer the green light is). Therefore, it is necessary to develop a novel luminescent material with high efficiency and high color purity for ultra-pure green OLED devices towards ultra-high definition display technology.
In order to solve the above technical problems, the present invention provides a B/N organic electroluminescent material and a preparation method and use thereof.
A novel B/N organic electroluminescent material is provided, wherein the B/N organic electroluminescent material includes DBTN-1 and/or DBTN-2, wherein the structural formulas of DBTN-1 and DBTN-2 are as follows:
A method for preparing the novel B/N organic electroluminescent material is provided, including the following steps:
(3) subjecting
In one example of the present invention, in step (1) or step (2), the alkali is selected from the group consisting of potassium tert-butoxide, sodium tert-butoxide, cesium carbonate and any combination thereof.
In one example of the present invention, in step (1), the organic solvent is selected from the group consisting of dimethylformamide, toluene, m-xylene and any combination thereof.
In one example of the present invention, in step (1), the molar ratio of the alkali to 3,6-di-tert-butylcarbazole is 1.5-2.5:1.
In one example of the present invention, in step (2), the molar ratio of the metal catalyst to
is 1:10-12.
In one example of the present invention, in step (2), the metal catalyst is selected from the group consisting of palladium chloride, palladium acetate, tris(dibenzylideneacetone)dipalladium, the ligand 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl and any combination thereof.
In one example of the present invention, in step (3), the lithium reagent is selected from the group consisting of tert-butyllithium, n-butyllithium, sec-butyllithium and any combination thereof.
In one example of the present invention, in step (3), the ultra-dry reagent is selected from the group consisting of tert-butylbenzene, o-xylene, trimethylbenzene and any combination thereof.
In one example of the present invention, in step (3), the molar ratio of the lithium reagent to
is 5-6:1.
In one example of the present invention, in step (3), the B/N organic electroluminescent material obtained by the reaction is a mixture of DBTN-1 and DBTN-2, and the two are further separated by silica gel chromatography to obtain purified DBTN-1 and DBTN-2.
An organic electroluminescent device is provided, including the B/N organic electroluminescent material.
Compared with the prior art, the technical scheme of the present invention has the following advantages:
The novel B/N organic electroluminescent materials DBTN-1 and DBTN-2 provided in the present invention exhibit narrowband spectra with extremely small full width at half maxima (FWHM) values, extremely high photoluminescence quantum yields and efficient TADF feature in solution/doped thin films, so they can be used in OLEDs.
OLEDs based on DBTN-1 and DBTN-2 as emitter can realize ultra-pure green electroluminescence with high efficiency, high color purity and low efficiency roll-off. Therefore, the novel DBTN-1 and DBTN-2 of the present invention can be used as components of ultra-pure green OLEDs with high efficiency and high color purity.
In order to make the contents of the present invention easier to be understood clearly, the present invention will be further described in detail according to specific examples of the present invention with reference to the attached drawings, in which
The present invention will be further described with reference to the attached drawings and specific examples, so that those skilled in the art can better understand implement the present invention, but the examples given are not taken as limitations of the present invention.
Under nitrogen atmosphere, 5.6 g (20 mmol) of 3,6-di-tert-butylcarbazole, 4.2 g (20 mmol) of 2-fluoro-6-bromochlorobenzene, 9.8 g (30 mmol) of cesium carbonate and 200 mL of the ultra-dry N,N-dimethylformamide solvent were sequentially added into a 250 mL two-neck flask. After nitrogen replacement, the obtained reaction solution was heated to 150° C. and stirred for 24 hours. The reaction was cooled to room temperature, and slowly poured into 500 mL of deionized water, stirred and filtered to obtain a white filter cake. The obtained product was further purified by silica gel column with PE:DCM (6:1) as the eluent, to obtain 9.0 g white solid with a yield of 96%.
Product characterization: 1H NMR (600 MHz, CDCl3-d) δ 8.16 (dd, J=3.5, 1.8 Hz, 2H), 7.80 (dt, J=8.1, 1.2 Hz, 1H), 7.45 (ddt, J=8.2, 6.1, 1.7 Hz, 3H), 7.31 (t, J=8.0 Hz, 1H), 7.00 (dd, J=8.5, 2.0 Hz, 2H), 1.47 (d, J=2.6 Hz, 18H). 13C NMR (151 MHZ, CDCl3-d) δ 143.13, 139.11, 137.28, 134.52, 133.58, 129.69, 128.31, 124.53, 123.70, 123.37, 116.37, 109.38, 34.75, 32.02. MS (MALDI-TOF). Calcd for C26H27BrClN: 468.86; Found: 468.69.
Under nitrogen atmosphere, 5.2 g (11 mmol) of Intermediate 1, 746 mg (5 mmol) of 4-tert-butylaniline, 458 mg (0.5 mmol) of tris(dibenzylideneacetone)dipalladium, 290 mg (1 mmol) of tri-tert-butylphosphine tetrafluoroborate, 2.0 g (30 mmol) of sodium tert-butoxide and 150 mL of the ultra-dry toluene solvent were sequentially added into a 250 mL two-neck flask. After being replaced with nitrogen for three times, the reaction solution was heated to reflux temperature and stirred for 24 hours. The reaction was cooled to room temperature, and then extracted with dichloromethane and deionized water. The organic phase was collected, dried with anhydrous sodium sulfate, and concentrated with rotary evaporator. The obtained product was further purified by silica gel column with PE:EA (4:1) as the eluent, to obtain 3.8 g white solid with a yield of 82%.
Product characterization: 1H NMR (600 MHz, CDCl3-d) δ 8.13 (t, J=1.7 Hz, 4H), 7.44-7.38 (m, 8H), 7.31 (ddt, J=16.5, 7.0, 2.2 Hz, 4H), 7.00 (d, J=8.6 Hz, 4H), 6.92 (dd, J=8.6, 1.5 Hz, 2H), 1.45 (d, J=1.5 Hz, 36H), 1.33 (s, 9H). 13C NMR (151 MHz, CDCl3-d) δ 146.39, 145.60, 144.57, 142.76, 139.22, 137.62, 131.17, 128.20, 127.71, 126.65, 126.09, 123.55, 123.26, 121.13, 116.27, 109.43, 34.72, 34.28, 32.02, 31.44. MS (MALDI-TOF). Calcd for C62H67Cl2N3: 925.14; Found: 925.03.
Under nitrogen atmosphere, 1.9 g (2 mmol) of Intermediate 2 and 60 mL of the ultra-dry tert-butyl benzene solvent were sequentially added into a 100 mL two-neck flask. After nitrogen replacement, the reaction solution was cooled to −40° C. Then, 3.1 mL of tert-butyllithium (5 mmol) in n-pentane (1.6 mol/L) was slowly added dropwise. After the reaction was stirred at 60° C. for 6 hours, the reaction solution was cooled to −40° C. again. Then, 0.5 mL of boron tribromide (5 mmol) was added dropwise, and warmed slowly to room temperature, and stirred for 6 hours. Subsequently, 0.8 mL of N,N-diisopropylethylamine was slowly added under the ice-water bath. Then the reaction solution was heated to 120° C. for 12 hours. The reaction was cooled to room temperature, and methanol was slowly added to quench the reaction, and then extracted with a large amount of dichloromethane and deionized water. The organic phase was collected, dried with anhydrous sodium sulfate, and concentrated with rotary evaporator. The obtained product was further purified by silica gel column with PE as the eluent, to obtain 80 mg orange solid DBTN-2 with a yield of 5% and 10 mg orange solid DBTN-1 with a yield of 1%, respectively.
Characterization of Compound DBTN-2: 1H NMR (600 MHz, CDCl3-d) δ 9.17 (dd, J=8.5, 1.6 Hz, 1H), 9.07 (d, J=1.8 Hz, 1H), 8.88 (d, J=1.8 Hz, 1H), 8.84 (d, J=2.4 Hz, 1H), 8.60 (dd, J=8.6, 2.2 Hz, 1H), 8.57-8.52 (m, 2H), 8.48 (d, J=1.8 Hz, 1H), 8.38 (d, J=8.6 Hz, 1H), 8.29 (d, J=2.0 Hz, 2H), 8.26 (dd, J=8.1, 2.0 Hz, 1H), 8.21-8.17 (m, 1H), 7.94 (d, J=8.3 Hz, 1H), 7.76-7.65 (m, 3H), 7.56 (dd, J=8.9, 2.5 Hz, 1H), 1.70 (s, 18H), 1.54 (s, 18H), 1.52 (s, 9H). 13C NMR (151 MHz, CDCl3-d) δ 148.34, 147.54, 146.11, 145.90, 145.42, 145.11, 144.96, 144.89, 142.15, 141.46, 141.23, 138.54, 138.29, 131.59, 130.60, 129.78, 129.60, 127.55, 126.92, 124.54, 124.35, 124.09, 123.58, 122.64, 120.51, 120.19, 117.40, 117.18, 115.51, 114.73, 113.78, 108.76, 108.32, 35.29, 35.24, 34.83, 34.78, 34.62, 32.32, 32.25, 31.86, 31.81, 31.50. MS (MALDI-TOF). Calcd for C62H63B2N3: 871.83; Found: 871.48.
Characterization of Compound DBTN-1: 1H NMR (600 MHZ, CDCl3-d) δ 8.33 (d, J=2.4 Hz, 1H), 7.94-7.90 (m, 1H), 7.61 (d, J=7.7 Hz, 1H), 7.48 (dd, J=13.6, 7.1 Hz, 2H), 7.28-7.17 (m, 3H), 7.04 (dd, J=6.4, 1.3 Hz, 1H), 1.35 (s, 9H). 13C NMR (151 MHz, CDCl3-d) δ 151.22, 150.94, 150.93, 148.05, 146.77, 146.39, 144.83, 144.04, 136.87, 133.91, 133.78, 130.88, 130.82, 130.51, 130.34, 130.25, 127.90, 127.00, 124.22, 122.55, 122.52, 121.61, 121.14, 118.87, 116.15, 115.57, 111.96, 35.99, 34.93, 31.34, 31.32, 31.28, 31.08. MS (MALDI-TOF). Calcd for C62H63B2N3: 871.83; Found: 871.54.
Under nitrogen atmosphere, 5.6 g (20 mmol) of 3,6-di-tert-butylcarbazole, 4.2 g (20 mmol) of 2-fluoro-6-bromochlorobenzene, (30 mmol) of potassium tert-butoxide and 200 mL of the ultra-dry N,N-dimethylformamide solvent were sequentially added into a 250 mL two-neck flask. After nitrogen replacement, the obtained reaction solution was heated to 150° C. and stirred for 24 hours. The reaction was cooled to room temperature, and then slowly poured into 500 mL of deionized water, stirred and filtered to obtain a white filter cake. The obtained product was further purified by silica gel column with PE:DCM (6:1) as the eluent, to obtain 9.6 g white solid.
Under the protection of nitrogen, 5.2 g (11 mmol) of Intermediate 1, 746 mg (5 mmol) of 4-tert-butylaniline, (0.5 mmol) of palladium acetate, 290 mg (1 mmol) of tri-tert-butylphosphine tetrafluoroborate, 2.0 g (30 mmol) of sodium tert-butoxide and 150 mL of the ultra-dry toluene solvent were sequentially added into a 250 mL two-neck flask. After being replaced with nitrogen for three times, the reaction solution was heated to reflux temperature and stirred for 24 hours. The reaction was cooled to room temperature, and then extracted with dichloromethane and deionized water. The organic phase was collected, dried with anhydrous sodium sulfate, and concentrated with a rotary evaporator. The obtained product was further purified by silica gel column with PE:EA (4:1) as the eluent, to obtain 4.2 g white solid.
Under nitrogen atmosphere, 1.9 g (2 mmol) of Intermediate 2 and 60 mL of the ultra-dry tert-butyl benzene solvent were sequentially added into a 100 mL two-neck flask. After nitrogen replacement, the reaction solution was cooled to −40° C. Then, 3.1 mL of n-butyllithium (5 mmol) in n-pentane (1.6 mol/L) was slowly added dropwise. After the reaction was stirred at 60° C. for 6 hours, the reaction solution was cooled to −40° C. again. Then, 0.5 mL of boron tribromide (5 mmol) was added dropwise, and warmed slowly to room temperature, and stirred for 6 hours. Subsequently, 0.8 ml of N,N-diisopropylethylamine was slowly added under the ice-water bath. Then, the reaction solution was heated to 120° C. for 12 hours. The reaction was cooled to room temperature, and methanol was slowly added to quench the reaction, and then extracted with a large amount of dichloromethane and deionized water. The organic phase was collected, dried with anhydrous sodium sulfate, and concentrated with rotary evaporator. The obtained product was further purified by silica gel column with PE as the eluent, to obtain 75 mg orange solid DBTN-2 and 8.5 mg orange solid DBTN-1, respectively.
Under nitrogen atmosphere, 5.6 g (20 mmol) of 3,6-di-tert-butylcarbazole, 4.2 g (20 mmol) of 2-fluoro-6-bromochlorobenzene, (30 mmol) of sodium tert-butoxide and 200 mL of the ultra-dry m-xylene solvent were sequentially added into a 250 mL two-neck flask. After nitrogen replacement, the reaction solution was heated to 150° C. and stirred for 24 hours. The reaction was cooled to room temperature, and then slowly poured into 500 mL of deionized water, stirred and filtered to obtain a white filter cake. The obtained product was further purified by silica gel column with PE:DCM (6:1) as the eluent, to obtain 8.5 g white solid.
Under nitrogen, 5.2 g (11 mmol) of Intermediate 1, 746 mg (5 mmol) of 4-tert-butylaniline, (0.5 mmol) of palladium chloride, 290 mg (1 mmol) of tri-tert-butylphosphine tetrafluoroborate, 2.0 g (30 mmol) of sodium tert-butoxide and 150 mL of the ultra-dry toluene solvent were sequentially added into a 250 mL two-neck flask. After being replaced with nitrogen for three times, the reaction solution was heated to reflux temperature and stirred for 24 hours. The reaction was cooled to room temperature, and then extracted with dichloromethane and deionized water. The organic phase was collected, dried with anhydrous sodium sulfate, and concentrated with rotary evaporator. The obtained product was further purified by silica gel column with PE:EA (4:1) as the eluent, to obtain 4.0 g white solid.
Under nitrogen atmosphere, 1.9 g (2 mmol) of Intermediate 2 and 60 mL of the ultra-dry o-xylene solvent were sequentially added into a 100 mL two-neck reaction bottle. After nitrogen replacement, the reaction solution was cooled to −40° C. Then, 3.1 mL of sec-butyllithium (5 mmol) in n-pentane (1.6 mol/L) was slowly added dropwise. After the reaction was stirred at 60° C. for 6 hours, the reaction solution was cooled to −40° C. again. Then, 0.5 mL of boron tribromide (5 mmol) was added dropwise, and warmed slowly to room temperature, and stirred for 6 hours. Subsequently, 0.8 mL of N,N-diisopropylethylamine was slowly added under the ice-water bath. Then the reaction solution was heated to 120° C. for 12 hours. The reaction was cooled to room temperature, and methanol was slowly added to quench the reaction, and then extracted with a large amount of dichloromethane and deionized water. The organic phase was collected, dried with anhydrous sodium sulfate, and concentrated with rotary evaporator. The obtained product was further purified by silica gel column with PE as the eluent, to obtain 85 mg orange solid DBTN-2 and 8.5 mg orange solid DBTN-1, respectively.
Photophysical characteristics of DBTN-2 obtained in Example 1 were investigated in toluene solution and in SF3-TRZ film with doping concentration of 2.5 wt %. The results are shown in Table 1.
Wherein the Δabs, λem, Stokes shift, FWHM, ES, ET, ΔEST, and PLQY represent the peak position of absorption spectrum, the peak position of fluorescence spectrum, the stokes shift, the full width at half maxima of the spectrum, the energy level of the lowest excited singlet state, the energy level of the lowest excited triplet state, the energy level difference between the lowest excited singlet and the lowest excited triplet states, and the photoluminescence quantum yield, respectively. From the above results, it can be seen that the fluorescence spectrum of this material in dilute solution and doped film is in the green region, with an extremely small stokes shift, narrow FWHM and high luminescent efficiency.
The temperature-dependent transient decay curve of 2 wt % DBTN-2 doped SF3-TRZ film was further measured, as shown in
Taking the material of Example 1 as example, the fabrication and performance evaluation of organic electroluminescent devices were carried out.
A glass plate with indium tin oxide (ITO) transparent electrodes was used as a substrate, wherein ITO pattern width is 3 mm. The substrate was washed with an ITO detergent and treated with ozone UV for 15 min. Then, the substrate was put into a vacuum evaporation chamber and vacuum evaporation method was used to evaporate each layer to fabricate an OLED device with a luminescent area of 10 mm2 as shown in
First, the aforementioned substrate was placed into a vacuum evaporation chamber and depressurized to 1×10−4 Pa. Then, on the glass substrate 1 shown in
A DC current was applied to the prepared OLED devices and the performance was evaluated using a Spectrascan PR655 luminometer, and the current-voltage characteristics were measured using a computer-controlled Keithley 2400 digital source meter. As luminescence characteristics, the electroluminescence spectra, FWHM, CIE coordinate values, maximum brightness (cd/m2), external quantum efficiency (%), and power efficiency (1 m/W) were measured under variations in response to the applied DC voltage. The measured values of the fabricated devices were a peak wavelength at 520 nm, with a half-peak width of 29 nm and CIE color coordinate of (0.19, 0.74), a maximum external quantum efficiency of 35.2%, a maximum current efficiency of 132.9 cd/A, and a maximum power efficiency of 130.4 lm/W.
In summary, the novel high-efficiency, high color purity narrowband organic electroluminescent materials DBTN-1 and DBTN-2 provided by the present invention can be applied in high-efficiency, high color purity ultrapure green OLEDs. The DBTN-1 and DBTN-2 involved in the present invention exhibit narrowband green emission with extremely high fluorescence quantum yields and efficient TADF properties both in dilute solution and doped films. In particular, the OLEDs prepared with the above fluorescent dyes have the advantages of high efficiency and ultra-pure green electroluminescence with high color purity, which can be applied to ultra-high definition display technology and other applications. By extension, the novel high-efficiency, high color purity narrowband organic electroluminescent material in the present invention can also be applied to a variety of host-guest organic electroluminescent devices such as fluorescent light-emitting materials and phosphorescent light-emitting materials, and can be applied to energy-saving lighting and the like, in addition to flat panel displays and the like.
Obviously, the above embodiments are merely examples for the sake of clarity, and are not a limitation of the embodiments. For a person of ordinary skill in the art, other variations or changes can be made on the basis of the above description. It is neither necessary nor possible to exhaust all the embodiments herein. The obvious variations or changes derived therefrom are still within the scope of protection of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202111439232.3 | Nov 2021 | CN | national |
This application is a Continuation Application of PCT/CN2022/101011, filed on Jun. 24, 2022, which claims priority to Chinese Patent Application No. 202111439232.3, filed on Nov. 29, 2021, which is incorporated by reference for all purposes as if fully set forth herein.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2022/101011 | Jun 2022 | WO |
| Child | 18672801 | US |
