CN116217764A - Triazine polymer and preparation method and application thereof - Google Patents

Abstract

The invention belongs to the technical field of heat-activated delayed fluorescent materials, and discloses a triazine polymer, a preparation method thereof and application of the triazine polymer as a heat-activated delayed fluorescent material. The preparation method of the triazine polymer provided by the invention has the advantages of simple process and low cost; the triazine polymer provided by the invention has good application prospect in organic light-emitting diodes as a thermally activated delayed fluorescence luminescent material.

Description

Triazine polymer and preparation method and application thereof

Technical Field

The invention belongs to the technical field of thermal-activation delay fluorescent materials, and particularly relates to a triazine polymer, a preparation method thereof and application of the triazine polymer as a thermal-activation delay fluorescent material.

Background

Organic Light Emitting Diodes (OLEDs) are widely used in the field of electronic device display because of their advantages of simple structure, low starting voltage, simple structure, low driving voltage, flexibility, low cost, high luminous efficiency, etc., and the selection of the luminescent materials has a critical influence on the luminous performance of OLEDs. As the demands of display devices are increasing, the choice of luminescent materials that can be better applied to OLEDs is also a subject of constant research. The triazine structural compound is not only a classical organic luminescent material, but also one of luminescent materials with the widest application prospect in OLEDs, namely a Thermally Activated Delayed Fluorescence (TADF) material. The structure of the triazine compound is adjusted, different substituents are introduced or different types of condensed ring compounds are synthesized to improve the luminous efficiency of the device, and the triazine compound is a research hot spot in the field of flat panel display in recent years.

By adjusting the substituent groups of the triazine compound structure, the luminous efficiency of the material can be improved, and the derivatives have good luminous efficiency and device performance. Three compounds were designed and synthesized by Lee et al (Dong Ryun Lee, mount Kim, sang Kyu Jeon, look-Ho Hwang, child Won Lee, and Jun yob Lee. Design Strategy for 25%External Quantum Efficiency in Green and Blue Thermally Activated Delayed Fluorescent Devices,Adv Mater,2015,5861-5867), by introducing different aromatic groups onto the triazine structure, and increasing the number of donor units, a molecular design of high EQE was achieved in TADF devices, achieving high quantum fluorescence yields approaching 100% for green and blue OLEDs, and high EQE with efficiencies exceeding 25%. But the light-emitting efficiency is low and the emission spectrum is not pure due to the influence of the rigid plane structure of the molecule. Sung et al (Sung Moo Kim, sung Yong Byeon, seok-Ho Hwang and JunYeob Lee, rational design of host materials forphosphorescent organic light-emitting diodes by modifying the 1-position of carbazole, chem Commun,2015,10672-10677) synthesized four derivatives based on carbazole and triazine series, and introduced methyl-bearing carbazole groups into the donor unit with torsion space at the side branches, coupling of this polycarbazole modified structure, using host materials, could achieve quantum efficiencies higher than 20% in the device, and could provide power OLED devices as high as 104lm/W, but the results of not effectively balancing current densities were not satisfactory. Cui et al (Lin-Song Cui, alexander J.Gillett, xian-Kai Chen, ze-Sen Lin, richard H.friend, shou-Feng Zhang, hao Ye, emrys W.Evans.fast spin-flip enables efficient and stable organic electroluminescence from charge-transfer states, nature Photonics,2020, 636-642) designed and synthesized a high efficiency OLED light emitting material with multiple carbazole donors and triazine structures. The device shows a maximum EQE of 29.3%, the EQE low-efficiency attenuation at high brightness is only 2.3%, but the problem of slower intersystem crossing in the opposite direction, equipment stability and efficiency attenuation still exists. Niu et al (Rui Niu, jiuyan Li, di Liu, ruizhi Dong, wenkui Wei, houlu Tian, chunlong Shi, aversatile carbazole donor design strategy for blue emission switching from normal fluorescence to thermally activated delayed fluorescence, DYES AND PIGMENTS,2021, 1873-3743) designed triazine nuclei and carbazole building donor-acceptor type blue OLEDs, with molecular orbital spatial separation achieved by phenyl bridge structures and twisted spatial structures. And the TADF luminescent material with or without methyl contrast is designed, and the external quantum efficiency expressed in a pure blue luminescent device reaches 13.07 percent. But the structural characteristics and process limitations are not ideal for effective radiation and delay life, and still have a large lifting space. Four novel Benzonitrile-based polymer OLED host materials were designed by Zhou et al (Tao Zhou, kaizhi Zhang, qingpeng Cao, hui Xu, xinxin Ban, peng Zhu, qiale Li, linxing Shi, fengjie Ge and Wei Jiang, benzonitrile-based AIE polymer host with asimple synthesis process for high-efficiency solution-processable green and blue TADF organic light emitting diodes, journal ofMaterials Chemistry C,2022, 2109-2120). The maximum External Quantum Efficiency (EQE) of the green and blue TADF reaches 20.9% and 13.4%, respectively, and the remarkable improvement of the device efficiency shows that the TADF homopolymer with AIE property can effectively inhibit exciton self-quenching, which proves that the polymer has better film forming property, but the series of molecules have longer synthesis process and strict molecular polymerization proportion, and are not beneficial to mass production and practical application value of industry.

Disclosure of Invention

The invention aims to: in view of the above problems, the present invention provides a triazine polymer with heat stability, long delay life and high-efficiency fluorescence emission characteristics. It is another object of the present invention to provide a process for synthesizing such monomers and polymers which is simple and inexpensive. It is a further object of the invention to provide the use of the polymers as luminescent materials in OLEDs.

The technical scheme is as follows: the structural general formula of the triazine polymer is shown as the following formula:

wherein the value range of the polymerization degree n is 2-100000;

wherein the substituent R1 is independently selected from phenyl, carbazolyl, dimethyl carbazolyl, di-tert-butyl carbazolyl, phenoxazinyl, diphenylamino, phenothiazinyl and acridinyl;

similarly, the substituent R2 is independently selected from phenyl, carbazolyl, dimethylcarbazolyl, di-tert-butylcarbazolyl, phenoxazinyl, diphenylamino, phenothiazinyl, acridinyl;

the substituents R1 and R2 may be the same or different.

The above compound represented by R1-H: the chemical structural formulas of benzene, carbazole, dimethyl carbazole, di-tert-butyl carbazole, phenoxazine, diphenylamine, phenothiazine and acridine are shown in the following formula in sequence:

/>

wherein the substituents R3 are independently selected from hydrogen, methyl or alkyl chains having 1 to 10 carbon atoms; similarly, the substituents R4 are independently selected from hydrogen, methyl or alkyl chains having 1 to 10 carbon atoms. R3 and R4 may be the same or different.

Preferably, the triazine polymer structure is selected from any one of the following compounds:

/>

the preparation method of the triazine polymer comprises the following steps:

preparation of intermediate c: adding a compound a, namely 4-hydroxycarbazole and potassium carbonate, into a reaction vessel filled with an N, N-dimethylformamide DMF solvent, then injecting another raw material compound b, namely 4-chloromethyl styrene, and stirring for 6 hours at a reflux state of 80 ℃ while avoiding excessively long time to be changed into double substitution. After stopping the reaction, the reaction mixture was extracted with dichloromethane DCM, and the organic solvent was dried by spin-drying using a rotary evaporator, and the product was purified by silica gel chromatography to give compound c as a white solid.

The preparation process of the intermediate triazine compound f comprises the following steps: compound d and compound d' were dissolved in dried THF and cooled to 0 ℃; dropwise adding n-butyllithium n-BuLi into the mixture under the nitrogen atmosphere, and stirring the mixture for 2 hours; continuously under the nitrogen atmosphere, slowly adding the solution of the compound e, namely cyanuric chloride dissolved in Tetrahydrofuran (THF), stirring again, heating and refluxing. After the reaction, water was slowly added dropwise to quench the reaction, and the mixture was stirred with dichloromethane and extracted. Taking an organic phase, evaporating a solvent, recrystallizing with ethyl acetate to obtain a pale yellow solid, and drying to obtain an intermediate triazine compound f; when the substituent r1=r2, the compound d=compound d ', wherein the molar mass ratio of the compound d, the compound d' and the compound e is 1:1:1, the compound f with the same substituent is directly obtained by one-step mixing. When the substituents R1 and R2 are different, compounds d and e are first prepared according to 1:1, and then taking a compound d' with the same amount as the compound d to react to prepare the compound f with different substituent groups.

Preparing a triazine intermediate h: and dissolving a triazine compound f, a para-fluorobenzeneboronic acid compound g and a catalyst tetra-triphenylphosphine palladium in tetrahydrofuran, adding a potassium carbonate aqueous solution, heating to 70 ℃, stirring, and cooling to room temperature after the reaction is finished. The organic layer was extracted with water and dichloromethane, the solvent was removed from the organic layer, and then dried to give a white solid triazine intermediate h.

Preparation of compound monomer i: the intermediate compound h, the compound c, the potassium tert-butoxide and the N, N Dimethylformamide (DMF) are heated in a reaction vessel, stirred and refluxed. And adding water after the reaction is finished, filtering to obtain a solid, and separating and purifying through a silica gel chromatographic column to obtain a compound monomer i.

Preparing a final product triazine polymer, adding a polymer monomer i and an initiator azodiisobutyronitrile AIBN into a device provided with a chlorobenzene solution, freezing and removing oxygen in the solution through low-temperature technologies such as liquid nitrogen and the like, thawing in a nitrogen atmosphere, repeating for a plurality of times, then heating to 80 ℃ again, stirring for 48 hours, and adding a methanol solution after finishing, standing and settling to obtain the final product, namely the triazine polymer.

The invention also provides application of the triazine polymer material as a thermally activated delayed fluorescence luminescent material in an organic light-emitting diode.

As a preferred embodiment, the triazine polymer is doped into a host material, which is 2, 6-bis [3- (9H-carbazol-9-yl) phenyl ] pyridine, namely 26DCzPPy or bis [2- ((oxo) diphenylphosphino) phenyl ] ether, namely DPEPO, as a light-emitting layer material to be coated into a film as a light-emitting layer in an organic light-emitting diode.

As a preferred embodiment, the triazine polymer is doped at a concentration ranging from 10 to 100wt%;

as a preferred embodiment, the organic light emitting diode is manufactured by spin coating PEDOT: PSS as an injection layer on the surface of a conductive ITO substrate, then spin coating the material of the light emitting layer, and then depositing an electron transport layer and Ca/Ag electrode.

The principle of the invention: firstly, respectively adopting a C-N coupling reaction under the condition of inorganic salt potassium carbonate and a C-N coupling reaction under the condition of organic alkali N-butyllithium to prepare a compound intermediate, then adopting the C-N coupling reaction under the condition of organic salt potassium tert-butoxide to prepare the intermediate, and finally polymerizing an organic monomer under the condition of a free radical initiator. The designed molecular structure contains strong electron donating groups of benzene, carbazole, dimethyl carbazole, di-tert-butyl carbazole, phenoxazine, diphenylamine, phenothiazine and acridine, and the strong electron withdrawing structure triazine adopts benzene or benzene connection mode with an alkyl torque space form between the two structural units to ensure lower molecular orbital energy level difference. In addition, in order to solve the problem of poor film forming property of the molecules in the device manufacturing process, styrene crosslinking groups are introduced to enable the molecules to form polymer macromolecules so as to increase the film forming property and the device efficiency in the device manufactured by a solution method.

The beneficial effects are that: aiming at the problems that in the prior art, if a TADF small molecule evaporation mode is adopted for preparing an organic light-emitting diode OLED device, a flexible device is not easy to prepare in a large area, and the film forming performance of a small molecule material is poor; by using the existing TADF polymers, although having good film forming properties, the existing TADF polymer materials have complex preparation processes and low controllability. Aiming at the problem of poor film forming performance of improved small molecular materials, the triazine styrene polymer provided by the invention is used as a luminescent layer material of a device, and has the fluorescence quantum efficiency of 90% of a thermal activation delayed fluorescence molecular material under the better preparation condition, and has the photophysical data with the delayed fluorescence life of 9.4us and the polymer film forming performance of 1000cd/m under the better condition ² Current efficiency of luminance the photovoltaic performance of current efficiency optimum 6cd/a, which indicates that the polymer is advantageous for application value and commercial industrialization of OLED.

Drawings

FIG. 1 is a graph of average weight number distribution versus duty cycle for polymer A, B;

FIG. 2 is a thermal stability thermal decomposition weight loss (TGA) diagram of polymer A, B;

FIG. 3 is a thermal stability differential cyclic scan (DSC) of polymer A, B;

fig. 4 is an electrochemical oxidation, reduction current-voltage curve of polymer A, B;

FIG. 5 is a graph of the ultraviolet absorption and infrared emission spectra of polymer A, B in methylene chloride solution;

FIG. 6a is a photo-induced spectrum of Polymer A in four different solutions of toluene, dichloromethane, tetrahydrofuran, N, N-dimethylformamide;

FIG. 6B is a photo-induced spectrum of Polymer B in four different solutions of toluene, dichloromethane, tetrahydrofuran, N, N-dimethylformamide;

FIG. 7 is a graph of fluorescence and phosphorescence spectra of polymer A, B at low temperature;

FIGS. 8 and 9 are graphs of absorption and emission spectra of films made from DPEPO doped with polymer A, B;

FIG. 10 is a graph of the delayed fluorescence lifetime of a DPEPO fabricated film doped with polymer A, B;

fig. 11 is a graph of luminescence intensity versus voltage for polymer a doped in host material 26 DCzPPy.

Fig. 12 is a plot of current density versus voltage for polymer a doped in host material 26 DCzPPy.

Fig. 13 is a graph of luminance versus voltage for polymer a doped in host material 26 DCzPPy.

Fig. 14 is a graph of current efficiency versus luminance for polymer a doped in host material 26 DCzPPy.

Detailed Description

The invention is further described below with reference to the drawings and examples. The compounds described in the examples below are characterized ¹ H NMR、 ¹³ The C NMR nuclear magnetic data were measured using a 400-megasuperconducting nuclear magnetic instrument manufactured by Bruker, inc., using deuterated chloroform as a solvent. Mass spectra were measured on a Autoflex Speed MALDI-TOF system produced by bruckdalton.

Example 1: synthesis of triazine Polymer A

Preparing an intermediate product c, namely a carbazole-styrene crosslinking group compound: to a 250mL three-necked flask, 4-hydroxycarbazole (6 g,32.7 mmol), 4-chloromethylstyrene (6 g,40 mmol) and potassium carbonate (13.87 g,100.5 mmol) were added under nitrogen atmosphere, and then N, N-dimethylformamide (80 mL) was injected as a solvent, and the mixture was stirred at 80℃for six hours. After stopping the reaction, the organic solvent was spin-dried using a rotary evaporator and extracted with 100mL of water and 100mL of dichloromethane by 3 fractions, separated and purified by a silica gel column (eluent: PE/dcm=2/1, V/V) to give 6.4g of a white solid after rotary evaporation in 53.5% yield.

Nuclear magnetic hydrogen spectrum: ¹ H NMR(400MHz,Chloroform-d)δ8.35(d,J＝7.7Hz,1H),8.04(s,1H),7.57(d,J＝8.0Hz,2H),7.51(d,J＝8.0Hz,2H),7.41(d,J＝4.0Hz,2H),7.35(t,J＝8.0Hz,1H),7.29～7.22(m,1H),7.06(d,J＝8.0Hz,1H),6.87～6.77(m,1H),6.77～6.72(m,1H),5.83(d,J＝17.6Hz,1H),5.35(s,2H),5.31(d,J＝10.8Hz,1H).

preparation of triazine biscarbazole substituted compound f-1

9,9'- (6-chloro-1, 3,5-triazine-2, 4-diyl) bis (9H-carbazole), 9' - (6-chloro-1, 3,5-triazine-2, 4-compound) bis (9-hydrogen-carbazole): carbazole (3.64 g,22 mmol) was dissolved in 44mL of dried tetrahydrofuran solution and cooled to 0deg.C. N-butyllithium (8.8 mL,22 mmol) was added dropwise thereto at a content of 2.5mmol/mL under nitrogen atmosphere, followed by stirring for 2 hours. A solution of cyanuric chloride (1.84 g,10 mmol) dissolved in 20mL tetrahydrofuran which had also been dried and cooled to 0℃was added dropwise under nitrogen, and after stirring for 2 hours, the reaction was heated to 80℃and refluxed for 6 hours. After the reaction was completed, water was slowly added dropwise to quench the reaction, and 100mL of methylene chloride was added thereto, followed by stirring and extraction. The organic phase was taken and the solvent was evaporated, and a small amount of ethyl acetate was added for dissolution, and the solid was obtained by filtration, and recrystallized from ethyl acetate to obtain a pale yellow solid, which was dried to obtain the objective product 2.64g, yield 55%.

Nuclear magnetic hydrogen spectrum: ¹ H NMR(400MHz,Chloroform-d)δ8.96–8.87(m,4H),8.10–8.02(m,4H),7.48(m,J＝27.5,7.3,1.2Hz,8H)。

preparation of triazine intermediate compound h-1

9,9'- (6- (4-fluoro-3-methylphenyl) -1,3,5-triazine-2, 4-diyl) bis (9H-carbazole), 9' - (6- (4-fluoro-3-methyl) -1,3,5-triazine-2, 4-compound) bis (9H-carbazole): 9,9' - (6-chloro-1, 3,5-triazine-2, 4-compound) bis (9-hydrogen-carbazole) (1.35 g 3 mmol) and 4-fluorobenzeneboronic acid (0.448 g,3.2 mmol) were added to a 100mL three-necked flask, the inside of the flask was evacuated three times with a double-row tube so that the flask was under nitrogen atmosphere, 15mL of tetrahydrofuran and 2mol of potassium carbonate aqueous solution per liter were injected via syringe, stirred at 30℃for 30 minutes, tetrakis (triphenylphosphine) palladium (0.1 g,0.08 mmol) was added, and the reaction was completed after heating to 80℃for 6 hours. After cooling, the organic solvent was removed, water and dichloromethane were added to the mixture to conduct liquid extraction, and then the mixture was separated and purified by a silica gel column (eluent: PE/dcm=1/1, V/V) to obtain 1.25g of pale yellow solid in 75% yield.

Nuclear magnetic hydrogen spectrum: ¹ H NMR(400MHz,Chloroform-d)δ8.94(d,J＝8.3Hz,4H),8.50(t,J＝6.5Hz,2H),8.03(d,J＝7.5Hz,4H),7.46(t,J＝7.7Hz,4H),7.37(t,J＝7.2Hz,4H),7.17(t,J＝2.5Hz,1H),2.45–2.35(s,3H).

mass spectrometry: MS (MADLI-TOF) M/z (M+H) ⁺ calcd.For C ₃₄ H ₂₂ FN ₅ ,519；found,519.000。

Preparation of monomeric triazine compound i-1, i.e. 9,9' - (6- (3-methyl-4- (4- ((4-methoxy)) -9-hydro-carbazolyl-9-) styrene) -1,3,5-triazine-2,4-diyl bis (carbazole): under nitrogen atmosphere, triazine intermediate compound h-1 (1.04 g,2 mmol), styrene crosslinking group compound c (0.66 g,2.2 mmol) and potassium tert-butoxide (0.24 g,2.2 mmol) are dissolved in 10mL DMF, stirred fully for 2 hours, heated to 140 ℃ and reacted for 2 hours. After cooling the reaction, 100mL of water at 0℃are added, the solid is obtained by filtration and dried, and finally purified by a silica gel column (eluent: PE/DCM=2/1, V/V) to give 0.08g of monomeric triazine compound d as a pale yellow solid in 5% yield.

Nuclear magnetic hydrogen spectrum: ¹ H NMR(400MHz,Chloroform-d)δ9.11(d,J＝5.8Hz,1H),9.09(d,J＝5.8Hz,2H),8.84(s,1H),8.76(d,J＝8.2Hz,1H),8.44(dd,J＝7.6,2.9Hz,1H),8.22(d,J＝7.8Hz,1H),8.13(d,J＝7.6Hz,3H),7.69(d,J＝8.2Hz,1H),7.62–7.50(m,8H),7.44(m,J＝15.5,6.4Hz,7H),7.37–7.30(m,2H),7.20(d,J＝8.1Hz,1H),6.83(m,J＝10.4,8.0Hz,1H),6.80–6.72(m,1H),5.83(m,J＝17.6,2.9Hz,1H),5.40(d,J＝5.6Hz,2H),5.31(d,J＝10.9Hz,1H),2.22(s,3H).

nuclear magnetic carbon spectrum: ¹³ C NMR(101MHz,Chloroform-d)δ172.36,164.82,164.75,155.40,154.77,142.37,140.90,140.54,140.29,140.20,138.91,137.95,137.88,137.45,136.91,136.55,136.48,136.37,132.49,132.44,129.95,129.87,128.19,128.15,127.82,127.78,127.54,127.05,126.92,126.63,126.58,126.55,126.15,126.10,125.90,125.30,123.63,123.49,123.38,123.31,122.71,120.51,120.30,119.99,119.80,119.77,117.69,117.59,116.76,114.25,114.14,112.75,110.31,109.95,109.34,105.87,103.12,102.18,77.26,76.89,70.15,70.02,31.97,29.75,29.71,29.41,22.74,18.31,14.17.

mass spectrometry: MS (MADLI-TOF) M/z (M+H) ⁺ calcd.C ₅₅ H ₃₈ N ₆ O,789；found,789.986。

Preparation of triazine Polymer A, namely triazine Polymer 5 described in the summary of the invention: triazine compound monomer i-1 (112 mg,0.14 mmol) and initiator AIBN (1 mg, 0.006mmol) are added into a device containing chlorobenzene solution, oxygen is frozen out through liquid nitrogen or other low temperature technology, the thawing is repeated for a plurality of times, then the solution is heated to 80 ℃ again and stirred for 48 hours, methanol solution is added after the completion, and the solution is statically settled to obtain 88mg of yellow solid, namely triazine polymer A, with the yield of 78.5%, mw=18608, mn=12850 and PDI (Mw/Mn) =1.40.

EXAMPLE 2 Synthesis of triazine Polymer B

The preparation of polymer B of example 2 comprises the following operations:

preparing a triazine intermediate compound h-2: 2-chloro-4, 6-diphenyl-1, 3,5-triazine (1.06 g,4 mmol) and 4-fluorobenzeneboronic acid (0.58 g,4.2 mmol) are added into a 100mL three-neck flask, the inside of the flask is pumped and discharged three times by a double-row pipe, so that the flask is in a nitrogen atmosphere, 10mLK CO3 solution (2M) and 20mL Tetrahydrofuran (THF) are injected through a syringe, after stirring for 30min at normal temperature (25 ℃), 0.12g of tetraphenylphosphine palladium is added, and then the mixture is heated to 75 ℃ for reaction for 6h, and cooling to room temperature is finished after the reaction. The organic solvent was first rotary evaporated, then water and dichloromethane were added to extract the organic layer, the solvent was removed from the organic layer, and the organic layer was dried. The dried solid was placed in a sublimation apparatus, and sublimated at 280℃under reduced pressure of 0.1 times standard atmospheric pressure and temperature by a vacuum pump to obtain 1.2g of a white solid. The yield was 92%.

Nuclear magnetic hydrogen spectrum: ¹ H NMR(400MHz,Chloroform-d)δ8.73(d,J＝6.2Hz,2H),8.69(m,J＝8.1Hz,4H),7.56–7.47(m,6H),7.18(t,J＝8.7Hz,2H).

preparation of monomeric triazine Compound i-2: into a dried 100mL three-necked flask, compound h-2 (1.0 g,3.05 mmol) and Compound c (0.92 g,3.07 mmol) were charged, and after three times of evacuation through a double-row tube, 0.34g (3.07 mmol) of potassium tert-butoxide was rapidly added under nitrogen atmosphere, 10mL of MSO was further injected, and after stirring for half an hour, the temperature was raised to 140℃and the reaction was continued for about 6 hours. The reaction was cooled to room temperature at the end, extracted three times with water and dichloromethane, and then purified by separation through a silica gel column (eluent: PE/dcm=2/1, V/V) to give 1.3g of pale yellow solid in 70% yield.

Nuclear magnetic hydrogen spectrum: ¹ H NMR(400MHz,Chloroform-d)δ9.05–8.98(m,2H),8.87–8.80(m,4H),7.82(d,J＝8.1Hz,2H),7.63(m,J＝9.6,6.9Hz,6H),7.60–7.57(m,2H),7.54–7.49(m,3H),7.45–7.40(m,1H),7.36(t,J＝8.0Hz,1H),7.31(t,J＝7.4Hz,1H),6.84(d,J＝7.9Hz,1H),6.78(m,J＝17.6,10.9Hz,1H),5.81(d,J＝17.6Hz,1H),5.39(s,2H),5.32–5.28(m,1H).

nuclear magnetic carbon spectrum: ¹³ C NMR(101MHz,Chloroform-d)δ171.62,155.15,141.80,141.54,137.14,136.66,136.33,135.97,134.82,132.48,130.41,128.84,128.82,128.53,127.53,126.69,126.34,125.11,123.25,122.95,120.50,113.93,109.14,102.92,102.46,69.83.

mass spectrometry: MS (MADLI-TOF) M/z (M+H) ⁺ calcd.C ₄₂ H ₃₀ N ₄ O,606；found，606.478。

Preparation of triazine Polymer B, namely triazine Polymer 1 described in the summary of the invention: monomer i-2 (248 mg,0.41 mmol), initiator AIBN (2 mg,0.012 mmol) gave after the polymerization process 183mg of the final triazine polymer B as a yellow solid in 73.7% yield, mw=18116, mn=12159, pdi (Mw/Mn) =1.48.

Figure 1 shows polymer A, B as measured by gas chromatography, and shows the relative number of polymer weights (m.w.) per unit volume tested, indicating that the polymer method is viable and gives better polymer macromolecular results.

Test example 1: thermal stability test of Material A, B

Figures 2 and 3 show thermogravimetric analysis of compounds a and B, scanning calorimetric analysis. The 5% decomposition temperature of the compound A, B is 442 ℃,427 ℃, and the glass transition temperature is 209 ℃ and 207 ℃. The thermal stability of the semiconductor device is better, which is beneficial to the stability of the device and the service life of the device.

Test example 2: electrochemical Properties of Compound A, B

FIG. 4 shows the electrochemical properties of compounds A and B; in the oxidation process, dichloromethane is used as a solvent, tetrahydrofuran is used as a reduction process, all solvents are subjected to water removal and deoxidation treatment, tetrabutylammonium hexafluorophosphate is used as an electrolyte, a glassy carbon electrode/platinum wire counter electrode/Ag/AgCl reference electrode is used, and a current-voltage curve is tested on an electrochemical workstation. As can be seen from the figure, the reduction process has a significant reversibility. The HOMO energy level and the LUMO energy level of A and B are respectively-1.85 eV and-5.21 eV,1.94eV and-5.24 eV through electrochemical initial peak position calculation.

Test example 3: photophysical Properties of materials

Fig. 5 shows the ultraviolet absorption and emission spectra of compound a in methylene chloride solution, which were tested in a fluorescence cuvette. As can be seen from the graph, the ultraviolet absorption peak of the compound A is at 290nm and 340nm, the emission peak is at 490nm, the ultraviolet absorption peak of the compound B is at 290nm and 320nm, and the emission peak is at 490nm, which indicate that the compound A is suitable for being used as a TADF luminescent material.

Figures 6a and 6B show photoluminescence spectra of compound a and compound B in four different solutions of toluene, N-dimethylformamide, tetrahydrofuran, dichloromethane, respectively, which data indicate blue shift of the emission spectra in toluene solution and also a significant red shift in N, N-dimethylformamide solvent.

Fig. 7 shows fluorescence and phosphorescence emission spectra at low temperature in a solution of compound A, B in dimethyltetrahydrofuran. At 10 ^-5 In the mol/L solution, a liquid nitrogen low-temperature device is used for testing an infrared spectrophotometer instrument. It can be seen that the main phosphorescence and fluorescence emission peaks of polymer A at low temperature 77K are at 420nm and 410nm, the triplet energy level and the singlet energy level are respectively 2.95eV and 3.02eV, and the main phosphorescence and fluorescence emission peaks of polymer B at low temperature 77K are at 465nm and 409nm, and the triplet energy level and the singlet energy level are respectively 2.67eV and 3.03eV.

Test example 4: absorption and emission spectrum of film sample made of DPEPO by doping material

Figure 8 shows the infrared fluorescence emission spectrum of compound A, B doped in DPEPO made film samples. Compound A, B was doped into DPEPO at a mass concentration of 6% wt to make a film, and then its fluorescence spectrum was measured. As can be seen from fig. 7, the main fluorescence emission peak of A, B is around 450nm, showing good fluorescence, and all fluorescence wavelengths are blue shifted with respect to the solution fluorescence photoluminescence spectrum due to the effect of DPEPO.

Figure 9 shows the uv absorption spectrum of compound A, B doped in DPEPO made film samples. Compound A, B was doped into DPEPO at a mass concentration of 6% wt to make a film, which was then measured for uv absorbance spectrum. As can be seen from FIG. 8, there are absorption peaks at 290nm and 340nm, respectively.

Test example 5: delayed fluorescence lifetime and fluorescence quantum efficiency of material doped in DPEPO made film sample

Fig. 10 shows a delayed fluorescence lifetime plot of compound A, B. The relevant life test was carried out by doping the film prepared from DPEPO with a transient spectrometer, also in a proportion of 6% by weight, excited with a xenon lamp at a wavelength of 340nm, as shown in the figure, the instrument giving relevant fitting data, delaying the fluorescence life τ ₁ /τ ₂ ＝9.4(75.96％)/53.8 (24.04%) μs,2.5 (17.34%)/9.7 (82.66%) μs. These data indicate that the polymers made from such D-A type monomers have excellent delayed fluorescence lifetime and are expected to be high efficiency TADF devices. Also on this test instrument, fluorescence quantum efficiencies were measured as 38% and 90% respectively using the form of an integrating sphere.

Example 3 preparation of an OLED device with Polymer Material A

In this embodiment, the compound 26DCzPPy is used as a host material, and the guest polymer material a is doped into the host material according to different doping ratios, so as to obtain a series of devices.

The device structure is ITO/PEDOT, PSS/(26DCzPPy: xwt%)/TPBI/Ca, ag, namely the light-emitting layer is a main material with the doping concentration of Xwt%, wherein X=10, 20, 30, 50, 100.TPBI is used as an electron injection layer, and Ca: ag is used as a cathode.

In the specific implementation process, the OLED device is prepared by adopting a solution process method, PEDOT: PSS is spin-coated on the surface of a conductive ITO substrate as an injection layer, then a luminescent layer is spin-coated, a polymer A is adopted as a luminescent layer material to be doped in a compound 26DCzPPy, then an electron transport layer and a Ca/Ag electrode are deposited, and the preparation of the multi-layer device with the structure of ITO/PEDOT: PSS (30 nm)/(26DCzPPy: xwt%) (30 nm)/TPBI (35 nm)/Ca: ag (15:100 nm) is completed. The specific operation steps are as follows:

etching ITO glass to make the width of each ITO glass luminous strip be 2.3mm, placing the ITO glass on a special polytetrafluoroethylene substrate frame, soaking the ITO glass in methylene dichloride, performing ultrasonic treatment on the substrate frame to remove organic stains on the substrate, performing ultrasonic treatment on the substrate frame by using ultrapure water three times for 15min each time, performing ultrasonic treatment on the substrate frame by using acetone and ethanol for 20min each time, and finally drying the substrate frame at 120 ℃ for 20min; and irradiating the dried substrate for 20-30min by using an ultraviolet lamp, so that the affinity of the surface to PEDOT: PSS is increased, and the hole injection capability is enhanced. Spin-coating PEDOT to PSS at 3000r/s to obtain a film thickness of about 30nm, and annealing at 120deg.C for 20min; the guest polymer materials a and 26DCzPPy were prepared as a chloroform solution (x=10, 20, 30, 50, 100) of 4mg/mL at a ratio of Xwt%, and stirred for more than 10 hours to allow the materials to be sufficiently dissolved. Spin-coating the solution on the upper layer in a glove box in nitrogen atmosphere at a rotating speed of 3000r/min for 30s, annealing for 20min at 120 ℃ to obtain a luminescent layer film with the thickness of 30 nm; at a vacuum level of less than 1X 10 ^-5 Pa, in per second

TPBi of 35nm was evaporated as an electron transport layer, after which an electrode of 2mm width was scraped. Next, 15nm of calcium was vacuum evaporated as an electron injection layer and 100nm of silver was used as a cathode, and finally device fabrication was completed.

FIG. 11 shows an electroluminescent spectrum of a device with polymer A doped at 10wt% in a 26DCzPPy host material at a start-up voltage. The abscissa in the figure is the wavelength range, and the ordinate is the electroluminescent intensity. As can be seen from the graph, the maximum emission peak wavelength of electroluminescence is kept at 450nm with the change of the working voltage, and is a typical blue light material.

Fig. 12 shows a current density-voltage curve for polymer a doped into host material 26DCzPPy at different concentrations. The voltage is plotted on the abscissa and the current density is plotted on the ordinate, and the current density of 10% wt doping concentration reaches 1200mA/cm at an operating voltage of 9V ² Its color coordinates CIE (0.17,0.12).

Fig. 13 shows the brightness-voltage curve of polymer a doped into host material 26DCzPPy at different concentrations. The abscissa in the figure is voltage, and the ordinate is device brightness. The brightness of the device doped with different proportions reaches 5000cd/m when the working voltage is 8V ² The color coordinates CIE (0.16,0.11) of the fabricated device were doped at a concentration of 20% wt.

Fig. 14 shows the efficiency-brightness curves of polymer a doped into host material 26DCzPPy at different concentrations. The abscissa in the figure is luminance, and the ordinate is device current efficiency. In which the device at a doping level of 10% wt is at 1000cd/m ² The current efficiency of the luminance is optimal, reaching 6cd/a.

Claims (7)

1. A triazine polymer, characterized in that the chemical structural formula of the triazine polymer is shown as follows:

wherein the value range of the polymerization degree n is 2-100000; the substituent R1 and the substituent R2 are both independently selected from any one of phenyl, carbazolyl, dimethyl carbazolyl, di-tert-butyl carbazolyl, phenoxazinyl, diphenylamino, phenothiazinyl or acridinyl; the substituent R3 and the substituent R4 are both independently selected from any one of hydrogen, methyl or an alkyl chain having 1 to 10 carbon atoms.

2. A triazine-based polymer according to claim 1, wherein the triazine-based polymer structure is selected from any one of the following compounds:

/>

3. a process for the preparation of triazine polymers, characterized in that it comprises the following steps:

adding a compound a, namely 4-hydroxycarbazole and potassium carbonate, into a reaction vessel filled with an N, N-dimethylformamide DMF solvent, then injecting another raw material compound b, namely 4-chloromethyl styrene, stirring for 6 hours at a reflux state of 80 ℃, and simultaneously avoiding excessively long time to be changed into double substitution; after stopping the reaction, separating and extracting with dichloromethane DCM, spin-drying the organic solvent with a rotary evaporator, and separating and purifying by a silica gel chromatographic column to obtain a white solid intermediate, namely a compound c;

compound d and compound d' were dissolved in dried THF and cooled to 0 ℃; dropwise adding n-butyllithium n-BuLi into the mixture under the nitrogen atmosphere, and stirring the mixture for 2 hours; continuously adding a compound e, namely cyanuric chloride, slowly in a tetrahydrofuran THF solution under the nitrogen atmosphere, stirring again, heating and refluxing; after the reaction is finished, slowly adding water dropwise for quenching, stirring with dichloromethane, and extracting; taking an organic phase, evaporating a solvent, recrystallizing with ethyl acetate to obtain a pale yellow solid, and drying to obtain an intermediate triazine compound f; when the substituent R1 = R2, the compound d = compound d ', the compound d' and the compound e are directly mixed in one step according to the molar mass ratio of 1:1:1 to obtain an intermediate product triazine compound f with the same substituent; when the substituents R1 and R2 are different, compounds d and e are first prepared according to 1:1, and then taking a compound d' with the same amount as the compound d to react to prepare an intermediate product triazine compound f with different substituents;

dissolving a triazine compound f, a para-fluorobenzeneboronic acid compound g and a catalyst tetra-triphenylphosphine palladium in tetrahydrofuran, adding a potassium carbonate aqueous solution, heating to 70 ℃, stirring, and cooling to room temperature after the reaction is finished; extracting the organic layer by adding water and dichloromethane, removing the solvent from the organic layer, and then drying to obtain a white solid, namely an intermediate product triazine intermediate h;

heating an intermediate compound h, a compound c, potassium tert-butoxide and N, N-Dimethylformamide (DMF) in a reaction vessel, stirring and refluxing; adding water after the reaction is finished, filtering to obtain a solid, and separating and purifying by a silica gel chromatographic column to obtain a compound monomer i;

adding a polymer monomer i and an initiator azodiisobutyronitrile AIBN into a device provided with a chlorobenzene solution, freezing to remove oxygen in the solution through low-temperature technologies such as liquid nitrogen and the like, thawing in a nitrogen atmosphere, repeating for a plurality of times, heating to 80 ℃ again, stirring for 48 hours, and adding a methanol solution after finishing, standing and settling to obtain a final product, namely the triazine polymer;

4. use of the triazine polymer as claimed in claim 1 as a thermally activated delayed fluorescence luminescent material in organic light emitting diodes.

5. Use of a triazine polymer as claimed in claim 4 as a thermally activated delayed fluorescence light emitting material in an organic light emitting diode, wherein the triazine polymer is doped in a host material as a light emitting layer material coated as a light emitting layer in an organic light emitting diode, the host material being 26DCzPPy or DPEPO.

6. Use of a triazine-based polymer as claimed in claim 5 as a thermally activated delayed fluorescence light emitting material in an organic light emitting diode fabricated by spin coating PEDOT: PSS as an injection layer on a surface of a conductive ITO substrate, followed by spin coating the light emitting layer material, followed by deposition of an electron transport layer, ca/Ag electrode.

7. Use of a triazine polymer as claimed in claim 5 as a thermally activated delayed fluorescence luminescent material in an organic light emitting diode wherein the triazine polymer is doped at a concentration in the range of 10 to 100wt%.

Images