Acridine-derived thermally activated delayed fluorescent material and electroluminescent device thereof

Abstract

The invention discloses an acridine-derived thermally activated delayed fluorescent material and an electroluminescent device thereof, and belongs to the technical field of organic luminescent materials. According to the fluorescent material, any electron withdrawing group is used as a receptor, an acridine derivative is used as a donor, nitrogen atoms of the acridine derivative are directly connected with the receptor, a dihedral angle between an electron donor and the electron receptor is increased, the dihedral angle is kept at an angle close to 90 degrees, meanwhile, the large-rigidity donor structure further reduces intramolecular vibration relaxation, and the fluorescence intensity is improved. In addition, HOMO delocalization can be further realized through side conjugation modification of acridine, so that large antiintersystem crossing rate and radiation decay rate are realized, the luminescence property of molecules is further improved, and the efficiency roll-off is reduced. The material provided by the invention can be used as an active material to be applied to organic electroluminescent devices.

Description

TECHNICAL FIELD

[0001] The present application relates to an acridine derivative and a preparation method thereof, and application of the material in an organic electroluminescent device, and belongs to the technical field of organic light-emitting materials. BACKGROUND

[0002] Since 1987, the research of organic electroluminescent material has entered a new era after C. W. Tang et al. of Kodak Company in the United States first prepared a small molecule thin film sandwich device by vacuum evaporation (C. W. Tang, S. A. Vanslyke, Applied Physics Letters, 1987, 51, 913). An organic electroluminescent device mainly comprises a positive electrode, a negative electrode and an active layer. The active layer is a light-emitting layer and is sandwiched between the positive and negative electrode layers to form a sandwich structure. In order to improve the injection and transmission of carriers and improve the working efficiency of the device, a carrier (hole and electron) injection layer, a carrier transmission layer and an exciton blocking layer are usually introduced. Holes and electrons are injected into the organic layer from the positive and negative electrodes under the action of an external electric field, and meet, recombine and radiate light in the light-emitting layer.

[0003] Organic electroluminescent materials can be generally divided into three types. The first type is a traditional fluorescent material. Since only 25% of singlet excitons are used for light emission, and 75% of triplet excitons are dissipated in a non-radiative form, the efficiency of the device is generally low. The second type is a phosphorescent material. It can utilize singlet and triplet light emission to achieve 100% internal quantum efficiency; however, due to the small number of material types and the use of some noble metals, the cost is high. The third type is a thermally activated delayed fluorescence (TADF) material. Due to the small splitting energy (ΔEST) between singlet and triplet states, ΔEst 75% of triplet excitons can reach singlet state through reverse intersystem crossing to emit light, so that the theoretical internal quantum efficiency reaches 100%. This kind of thermally activated delayed fluorescence material has the advantages of high brightness, high efficiency, wide coverage of light-emitting color, low cost, etc., and therefore has become the object of research by scientists at home and abroad, and is one of the most widely used electroluminescent materials at present.

[0004] Although theoretically TADF materials can achieve 100 % exciton utilization, in practice there are the following problems: (1) the target molecule not only needs strong charge transfer state characteristics of T1 and S1 state but also needs to have very small S1-T1 state energy level difference. Usually high T1 to S1 state exciton conversion rate can be achieved by fast reverse intersystem crossing, but at the same time it will lead to low S1 state radiation transition rate, therefore, it is difficult to have (or simultaneously achieve) high exciton utilization and high fluorescence radiation efficiency; (2) even if the doped device has been used to reduce the quenching caused by the concentration of triplet excitons, but most TADF devices still have serious efficiency roll-off under high current density, and the efficiency roll-off reaches 20%-40%.

[0005] In terms of the actual needs of the current OLED display lighting industry, the development of the current OLED material is still far from enough, which lags behind the requirements of panel manufacturing enterprises, and it is particularly important for material enterprises to develop higher performance organic functional materials. SUMMARY

[0006] To solve the problems in the prior art, the present application provides a novel organic thermally activated delayed fluorescence material with acridine derivative as donor, any electron-withdrawing group as acceptor, and the nitrogen atom directly connected to the acceptor, and an organic electroluminescent device, which is committed to realizing high external quantum efficiency and low efficiency roll-off.

[0007] The technical scheme adopted by the present application is as follows: an organic thermally activated delayed fluorescence material, which has the following structural formula:

[0008] In formula (1), A is selected from substituted or unsubstituted C5-C60 aryl, substituted or unsubstituted C3-C60 heteroaryl; R 1 -R 19 The same or different, each independently selected from hydrogen, sulfone group, cyano, alkyl, alkoxy, substituted or unsubstituted C6-C60 aryl, substituted or unsubstituted C3-C60 heteroaryl, or R 1 -R 19 The adjacent substituents form a structure connected to each other, and the structure connected to each other is C5-C60 aryl or C3-C60 heteroaryl; the substituents not forming the structure connected to each other are each independently selected from hydrogen, sulfone group, cyano, alkyl, alkoxy, substituted or unsubstituted C6-C60 aryl, or substituted or unsubstituted C3-C60 heteroaryl.

[0009] Preferably, the substituted C5-C60 aryl group, the substituted C3-C60 heteroaryl group, the substituted C6-C60 aryl group, the substituents are selected from one of hydrogen, halogen, cyano, C1-C60 alkyl group, C3-C30 cycloalkyl group, C6-C30 aryl group, C3-C30 heteroaryl group.

[0010] Preferably, A is selected from a common acceptor group, the acceptor group is selected from one of the following structures:

[0011] In the present invention, represents a bond.

[0012] Preferably, R 1 -R 19 are the same or different, each independently selected from hydrogen, methyl, phenyl, pyridyl, carbazolyl, triazinyl, tolyl, and boratabenzyl structures.

[0013] The substituents of the substituted methyl group, the substituted phenyl group, the substituted pyridyl group, the substituted carbazolyl group, the substituted triazinyl group, the substituted tolyl group, and the substituted boratabenzyl group are selected from one or a combination of two of hydrogen, cyano, C1-C6 alkyl group, C3-C30 cycloalkyl group, C6-C30 aryl group, C3-C30 heteroaryl group.

[0014] Preferably, the substituents of the substituted methyl group, the substituted phenyl group, the substituted pyridyl group, the substituted carbazolyl group, the substituted triazinyl group, the substituted tolyl group, and the substituted boratabenzyl group are phenyl, methyl, cyano.

[0015] Preferably, R 1 -R 19 The adjacent substituents form a structure connected to each other, the structure connected to each other is one of the following structures:

[0016] In the present invention, is a connection point.

[0017] Preferably, the thermally activated delayed fluorescence material has any one of the following structures:

[0018]

[0019]

[0020] The application also provides an organic electroluminescent device, comprising a first electrode, a second electrode and a light-emitting layer between the first electrode and the second electrode, wherein the light-emitting layer comprises any of the above-mentioned thermally activated delayed fluorescence materials.

[0021] Preferably, the light-emitting layer comprises the above-mentioned thermally activated delayed fluorescence material and an organic functional material, wherein the thermally activated delayed fluorescence material accounts for 0.01%-100% and the organic functional material accounts for 0-99.9% in terms of mass percentage.

[0022] The application provides an application of the above-mentioned organic electroluminescent device in an electronic device.

[0023] It should be noted that the application of the thermally activated delayed fluorescence material described in the application is not limited to the device structure, and the film thickness or the constituent material of each layer can be appropriately changed according to the basic properties of the structure of the specific compound in the application.

[0024] The preparation method of the organic device described in the application is a conventional method in the art. Alternatively, the preparation of the organic electroluminescent device comprises the following steps: taking a glass substrate with ITO evaporation as a transparent support substrate, and sequentially evaporating each organic layer and a metal electrode on the ITO film of the transparent substrate.

[0025] The functional material includes a hole injection material, a hole transport material, a hole blocking material, an electron injection material, an electron transport material, an electron blocking material, an exciton blocking material, a fluorescent light-emitting material, a phosphorescent light-emitting material, a host material and an organic dye.

[0026] The application also provides a preparation method of the above-mentioned thermally activated delayed fluorescence material. The synthesis route of the thermally activated delayed fluorescence material described in the application is shown in the following figure, and the specific synthesis steps include:

[0027]

[0028]

[0029] Take 1 equivalent of substituted or unsubstituted reactant 1 and 1.1 equivalent of substituted or unsubstituted reactant r1, then add 0.73 equivalent of phosphorus pentoxide and 2 ml of trifluoromethanesulfonic acid, stir the reaction at room temperature for 30 min. After the reaction is completed, pour into ice water to quench, adjust the pH to 12 with dilute sodium hydroxide solution, then extract with dichloromethane, after the organic solvent is evaporated, column chromatography is carried out to obtain intermediate 2. Intermediate 2 is prepared into intermediate 3 by Buchwald-Hartwig coupling reaction with an equal amount of substituted or unsubstituted aniline (r2). Take 1 equivalent of intermediate 3 and 1.1 equivalent of substituted or unsubstituted carbazole (r3), add cesium carbonate and an appropriate amount of N, N-dimethylformamide as the solvent, react at a temperature of 160 ℃ for 12 h, after the solvent is evaporated, column chromatography is carried out to separate to obtain intermediate 4. 1 equivalent of intermediate 4 is placed in a round-bottom flask, heated to 120 ℃, then 0.2 equivalent of p-toluenesulfonic acid monohydrate is added, heated to 160 ℃, then incubated for 15 min, then cooled to 40 ℃, dichloromethane is added, after the organic phase is evaporated, column chromatography is used to separate to obtain intermediate 6. Equal molar intermediate 6 and A-Br are subjected to Buchwald-Hartwig coupling reaction, and after column chromatography, the compound represented by formula (1) is obtained.

[0030] The beneficial effects of the present application: the thermal activation delayed fluorescence material provided by the present application has the structure of formula (1), by constructing a tetrahedral donor unit, realizing the delocalization of the HOMO orbital through conjugate extension, and combining with the acceptor unit at a specific position to prepare a luminescent molecule. Due to the steric effect, the tetrahedral donor simultaneously exists in the form of planar and bent structure. The planar structure is combined with the acceptor, so that a large torsion angle is generated between the donor unit and the acceptor unit, which reduces the overlap of the molecular frontier orbital, thereby reducing the energy level difference between the lowest excited singlet state and the triplet state, and improving the anti-inter-system crossing rate of the molecule; the bent configuration and conjugate extension can increase the delocalization of the highest occupied molecular orbital, which can maintain a small molecular frontier orbital overlap, increase the radiation transition rate of the molecule, and improve the photoluminescence efficiency of the molecule. The present application is expected to simultaneously improve the radiation transition rate and the anti-inter-system crossing rate, and thus the organic electroluminescent device containing the material can simultaneously realize high external quantum efficiency and low efficiency roll-off. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed in the specific embodiments or prior art description. Some of the drawings in the following description are some embodiments of the present application. Those skilled in the art can also obtain other drawings from these drawings without creating any creative labor.

[0032] Figure 1is a HOMO and LUMO distribution plot of the thermally activated delayed fluorescence material P1.

[0033] Figure 2 is a HOMO and LUMO distribution plot of the thermally activated delayed fluorescence material P2.

[0034] Figure 3 is a HOMO and LUMO distribution plot of the thermally activated delayed fluorescence material P5.

[0035] Figure 4 is a HOMO and LUMO distribution plot of the thermally activated delayed fluorescence material P6.

[0036] Figure 5 is a HOMO and LUMO distribution plot of the thermally activated delayed fluorescence material P21.

[0037] Figure 6 is a HOMO and LUMO distribution plot of the thermally activated delayed fluorescence material P22.

[0038] Figure 7 is an absorption and emission spectrum plot of the thermally activated delayed fluorescence material P1.

[0039] Figure 8 is an absorption and emission spectrum plot of the thermally activated delayed fluorescence material P2.

[0040] Figure 9 is an absorption and emission spectrum plot of the thermally activated delayed fluorescence material P5.

[0041] Figure 10 is an absorption and emission spectrum plot of the thermally activated delayed fluorescence material P6.

[0042] Figure 11 is an absorption and emission spectrum plot of the thermally activated delayed fluorescence material P21.

[0043] Figure 12 is an absorption and emission spectrum plot of the thermally activated delayed fluorescence material P22.

[0044] Figure 13 is a current efficiency-luminance-power efficiency plot of devices P1, P2, P10, P17 in device example 1. J-V-B

[0045] Figure 14 is a current efficiency-luminance-power efficiency plot of devices P1, P2, P10, P17 in device example 1.

[0046] Figure 15 is a current efficiency-luminance-power efficiency plot of devices P1, P2, P10, P17 in device example 1. DETAILED DESCRIPTION

[0047] ​The following examples are provided to better illustrate the present application and are not intended to limit the scope of the application. Any variation, modification or equivalent design of the examples which do not depart from the spirit and scope of the present application should be considered equivalent thereto and are intended to be covered by the present application.

[0048] Unless otherwise indicated, conventional methods of chemistry, molecular biology, recombinant DNA techniques and biochemistry were used. Unless otherwise indicated, all reagents were obtained from commercial suppliers such as Sigma-Aldrich, and used without further purification.

[0049] In some embodiments, the following 10 compounds are prepared as examples:

[0050] This example provides a method for preparing intermediates 6 and 7, comprising the following steps: Synthesis of intermediate 6: Reactants 1 (1.10 g, 5 mmol), benzene (391 mg, 5 mmol), trifluoromethanesulfonic acid (10 ml) and phosphorus pentoxide (518 mg, 3.65 mmol) were mixed and stirred at room temperature for half an hour. The reaction was quenched with 30 ml of ice water and alkalized to a pH of 12 with a dilute sodium hydroxide solution. Then extracted with dichloromethane and purified by column chromatography after removing the organic solvent by evaporation to obtain intermediate 2 (white powder, 1.25 g). Yield 90%. MS (MALDT-TOF): m / z 277.97 [M + ].

[0051] The reaction equation is as follows:

[0052] Intermediate 2 (1.39 g, 5 mmol) and aniline (466 mg, 5.5 mmol) were placed in a 100 ml reaction bottle with xylene (10 ml), and nitrogen was introduced for 10 min. Then, tris(dibenzylideneacetone)dipalladium (230 mg, 0.25 mmol), 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl (310 mg, 0.65 mmol), potassium carbonate (1.38 g, 10 mmol) were added, and the temperature was raised to 110 °C for 12 h. The solvent was evaporated and purified by column chromatography to obtain intermediate 3 (yellow solid, 1.16 g). Yield 80%. MS (MALDT-TOF): m / z 292.11 [M+].

[0053] The reaction equation is as follows:

[0054] Intermediate 3 (1.46 g, 5 mmol), carbazole (835 mg, 5.5 mmol) and cesium carbonate (3.26 g, 10 mmol) were added into a 100 ml reaction flask, and 15 ml of N,N-dimethylformamide was added as a solvent, and reacted under a nitrogen atmosphere at 160 °C for 12 h, and the solvent was evaporated and column chromatography was used for purification to obtain intermediate 4 (white powder, 986 mg). Yield 45%. MS (MALDT-TOF): m / z 438.17 [M + ].

[0055] The reaction equation is as follows:

[0056] Intermediate 4 (2.19 g, 5 mmol) was placed in a 100 ml reaction flask, nitrogen was introduced for 10 min, then the temperature was raised to 120 °C, and after stabilization, p-toluenesulfonic acid hydrate (1.90 g, 10 mmol) was added, the temperature was raised to 160 °C and kept for 30 min, then cooled to room temperature, dissolved in dichloromethane, and after evaporation of the solvent, column chromatography was used for separation, and polar petroleum ether: ethyl acetate = 25:1 was used for purification to obtain intermediate 6 (white solid, 840 mg), yield 40%. MS (MALDT-TOF): m / z 420.16 [M + ].

[0057] The reaction equation is as follows:

[0058] Synthesis of intermediate 7: Intermediate 3 (1.46 g, 5 mmol), phenylcarbazole (1.20 g, 5.5 mmol) and cesium carbonate (3.26 g, 10 mmol) were added into a 100 ml reaction flask, and 15 ml of N,N-dimethylformamide was added as a solvent, and reacted under a nitrogen atmosphere at 160 °C for 12 h, and the solvent was evaporated and column chromatography was used for purification to obtain intermediate 5 (white powder, 1.10 g). Yield 45%. MS (MALDT-TOF): m / z 488.19 [M + ].

[0059] The reaction equation is as follows:

[0060] Intermediate 5 (2.44 g, 5 mmol) was placed in a 100 ml reaction bottle, nitrogen was bubbled for 10 min, then the temperature was raised to 120 ℃, after stabilization, p-toluenesulfonic acid hydrate (1.90 g, 10 mmol) was added, the temperature was raised to 160 ℃ and kept for 30 min, then cooled to room temperature, dissolved in dichloromethane, after evaporation of the solvent, column chromatography was used for separation, and purification was performed with polar petroleum ether: ethyl acetate = 25:1 to obtain intermediate 6 (white solid, 940 mg) in a yield of 40%. MS (MALDT-TOF): m / z 470.18 [M + ]。

[0061] The reaction equation is as follows: Example 1

[0062] The present example provides a preparation method of a thermally activated delayed fluorescent material P1, comprising the following steps:

[0063] 1 mmol of intermediate 6 and 1.1 mmol of monobromobenzophenone, dimethyl sulfoxide (10 ml) were placed in a 100 ml reaction bottle, nitrogen was bubbled for 10 min, then cuprous iodide (96 mg, 0.5 mmol), o-phenanthroline (91 mg, 0.5 mmol), 18-crown-6 (133 mg, 0.5 mmol), potassium tert-butoxide (168 mg, 1.5 mmol) were added, the temperature was raised to 180 ℃ and reacted for 12 h, after the reaction was completed, the organic solvent was removed by reduced pressure distillation, and column chromatography was used for separation and purification with polar petroleum ether: dichloromethane = 10:1 to obtain the product P1, light green solid, in a yield of 25%. MS (MALDT-TOF): m / z 600.22 [M + ]。

[0064] Example 2 The present example provides a preparation method of a thermally activated delayed fluorescent material P2, comprising the following steps:

[0065] A 100-ml reaction flask was charged with 1 mmol of intermediate 7 and 1.1 mmol of monobromobenzophenone, dimethyl sulfoxide (10 ml), and nitrogen was bubbled for 10 min. Then, cuprous iodide (96 mg, 0.5 mmol), o-phenanthroline (91 mg, 0.5 mmol), 18-crown-6 (133 mg, 0.5 mmol), and potassium tert-butoxide (168 mg, 1.5 mmol) were added, and the temperature was raised to 180 °C for 12 h. After the reaction was completed, the organic solvent was removed by distillation under reduced pressure, and column chromatography was performed using polar petroleum ether:dichloromethane = 10:1 to isolate and purify the product P2, which was a light green solid with a yield of 25%. MS (MALDT-TOF): m / z 650.24 [M + ]。

[0066] Example 3 This example provides a method for preparing the thermally activated delayed fluorescence material P5, which includes the following steps:

[0067] A 100-ml reaction flask was charged with 1 mmol of intermediate 6 and 1.1 mmol of 7-bromo-5,9-dioxa-13b-bora-naphtho-[3,2,1-de]anthracene, dimethyl sulfoxide (10 ml), and nitrogen was bubbled for 10 min. Then, cuprous iodide (96 mg, 0.5 mmol), o-phenanthroline (91 mg, 0.5 mmol), 18-crown-6 (133 mg, 0.5 mmol), and potassium tert-butoxide (168 mg, 1.5 mmol) were added, and the temperature was raised to 180 °C for 12 h. After the reaction was completed, the organic solvent was removed by distillation under reduced pressure, and column chromatography was performed using polar petroleum ether:dichloromethane = 10:1 to isolate and purify the product P5, which was a light green solid with a yield of 25%. MS (MALDT-TOF): m / z 688.23 [M + ]。

[0068] Example 4 This example provides a method for preparing the thermally activated delayed fluorescence material P6, which includes the following steps:

[0069] A 100-ml reaction flask was charged with 1 mmol of intermediate 7 and 1.1 mmol of 7-bromo-5,9-dioxa-13b-bora-naphtho-[3,2,1-de]anthracene, dimethyl sulfoxide (10 ml), and purged with nitrogen for 10 min. Then, 96 mg (0.5 mmol) of cuprous iodide, 91 mg (0.5 mmol) of phenanthroline, 133 mg (0.5 mmol) of 18-crown-6 ether, and 168 mg (1.5 mmol) of potassium tert-butoxide were added. The reaction mixture was heated to 180 °C and reacted for 12 h. After the reaction was completed, the organic solvent was removed by distillation under reduced pressure. The product P5 was obtained by column chromatography using polar petroleum ether:dichloromethane = 10:1 as an eluent, and was a light yellow solid with a yield of 25%. MS (MALDI-TOF): m / z 738.25 [M + ]。

[0070] Example 5 This example provides a method for preparing the thermally activated delayed fluorescence material P9, comprising the following steps: A 100-ml reaction flask was charged with 1 mmol of intermediate 6 and 1.1 mmol of 2-(4-bromophenyl)-4,6-diphenyl-1,3,5-triazine, dimethyl sulfoxide (10 ml), and purged with nitrogen for 10 min. Then, 96 mg (0.5 mmol) of cuprous iodide, 91 mg (0.5 mmol) of phenanthroline, 133 mg (0.5 mmol) of 18-crown-6 ether, and 168 mg (1.5 mmol) of potassium tert-butoxide were added. The reaction mixture was heated to 180 °C and reacted for 12 h. After the reaction was completed, the organic solvent was removed by distillation under reduced pressure. The product P9 was obtained by column chromatography using polar petroleum ether:dichloromethane = 10:1 as an eluent, and was a light yellow solid with a yield of 25%. MS (MALDI-TOF): m / z 727.27 [M + ]。

[0071] Example 6

[0072] This example provides a method for preparing the thermally activated delayed fluorescence material P10, comprising the following steps:

[0073] Into a 100 ml reaction flask, 1 mmol of intermediate 7 and 1.1 mmol of 2-(4- bromophenyl)-4,6-diphenyl-1,3,5-triazine, dimethyl sulfoxide (10 ml) were placed, after nitrogen was bubbled for 10 min, cuprous iodide (96 mg, 0.5 mmol), bathophen (91 mg, 0.5 mmol), 18-crown-6 (133 mg, 0.5 mmol), potassium tert-butoxide (168 mg, 1.5 mmol) were added, and the reaction was heated to 180 °C for 12 h. After the reaction was completed, the organic solvent was removed by distillation under reduced pressure, and the product P10 was obtained by column chromatography separation and purification with polar petroleum ether: dichloromethane = 10:1, light yellow powder, yield 25%. MS (MALDT-TOF): m / z 777.29 [M + ]。

[0074] Example 7 The present example provides a method for preparing a thermally activated delayed fluorescent material P21, comprising the following steps:

[0075] Into a 100 ml reaction flask, 1 mmol of intermediate 6 and 1.1 mmol of 1-bromo-4- (phenylsulfonyl)-benzene, dimethyl sulfoxide (10 ml) were placed, after nitrogen was bubbled for 10 min, cuprous iodide (96 mg, 0.5 mmol), bathophen (91 mg, 0.5 mmol), 18-crown-6 (133 mg, 0.5 mmol), potassium tert-butoxide (168 mg, 1.5 mmol) were added, and the reaction was heated to 180 °C for 12 h. After the reaction was completed, the organic solvent was removed by distillation under reduced pressure, and the product P21 was obtained by column chromatography separation and purification with polar petroleum ether: dichloromethane = 10:1, light green powder, yield 25%. MS (MALDT-TOF): m / z 631.19 [M + ]。

[0076] Example 8 The present example provides a method for preparing a thermally activated delayed fluorescent material P22, comprising the following steps:

[0077] Into a 100-ml reaction flask were placed 1 mmol of intermediate 7 and 1.1 mmol of 1-bromo-4-(phenylsulfonyl)-benzene, dimethyl sulfoxide (10 ml). After nitrogen was bubbled for 10 min, cuprous iodide (96 mg, 0.5 mmol), o-phenanthroline (91 mg, 0.5 mmol), 18-crown-6 (133 mg, 0.5 mmol), and potassium tert-butoxide (168 mg, 1.5 mmol) were added. The mixture was heated to 180 °C for 12 h. After the reaction was completed, the organic solvent was removed by distillation under reduced pressure. The product P22 was obtained by column chromatography using polar petroleum ether:dichloromethane = 10:1 as the eluent. The product was a light green powder with a yield of 25%. MS (MALDT-TOF): m / z 686.20 [M + ]。

[0078] Example 9 This example provides a method for preparing the thermally activated delayed fluorescence material P17, comprising the following steps:

[0079] Into a 100-ml reaction flask were placed 1 mmol of intermediate 6 and 1.1 mmol of 3-bromo-10-phenylacridan-9(10H)-one, dimethyl sulfoxide (10 ml). After nitrogen was bubbled for 10 min, cuprous iodide (96 mg, 0.5 mmol), o-phenanthroline (91 mg, 0.5 mmol), 18-crown-6 (133 mg, 0.5 mmol), and potassium tert-butoxide (168 mg, 1.5 mmol) were added. The mixture was heated to 180 °C for 12 h. After the reaction was completed, the organic solvent was removed by distillation under reduced pressure. The product P17 was obtained by column chromatography using polar petroleum ether:dichloromethane = 10:1 as the eluent. The product was a light green solid with a yield of 25%. MS (MALDT-TOF): m / z 689.25 [M + ]。

[0080] Example 10 This example provides a method for preparing the thermally activated delayed fluorescence material P18, comprising the following steps:

[0081] Into a 100 ml reaction flask were placed 1 mmol of intermediate 7 and 1.1 mmol of 3-bromo-10-phenylacridan-9(10H)-one, dimethyl sulfoxide (10 ml), and nitrogen was bubbled for 10 min, then cuprous iodide (96 mg, 0.5 mmol), phenanthroline (91 mg, 0.5 mmol), 18-crown-6 (133 mg, 0.5 mmol), potassium tert-butoxide (168 mg, 1.5 mmol) were added, and the temperature was raised to 180 °C for 12 h. After the reaction was completed, the organic solvent was removed by distillation under reduced pressure, and column chromatography was performed using polar petroleum ether:dichloromethane = 10:1 to isolate and purify the product P18, which was a light green solid with a yield of 25%. MS (MALDT-TOF): m / z 739.26 [M + ]。

[0082] Example 11 This example provides the frontier molecular orbital distribution of the thermally activated delayed fluorescence material P1, P2, P5, P6, P21, P22.

[0083] The theoretical calculation of this example was performed using the Gaussian 09 program package. The ground state geometry of the molecule was optimized by density functional theory (Density Functional Theory) using B3LYP / 6-31g(d) as the basis set, and the frontier molecular orbital distribution of the molecule was calculated. The material uses any electron-withdrawing group as an acceptor and an acridine derivative as a donor, which is directly connected to the acceptor through its nitrogen atom, increases the dihedral angle between the electron donor and the electron acceptor, and keeps it at an angle of nearly 90 degrees. At the same time, the large rigid donor structure further reduces the intramolecular vibration relaxation, and the acridine side conjugation modification can further delocalize the HOMO, thereby achieving a large reverse intersystem crossing rate and a radiation decay rate, further improving the luminescence performance of the molecule and reducing the efficiency roll-off.

[0084] The molecular orbital distribution of this example is shown in Figures 1-6 From the figure, we can see that the HOMO of the six molecules is almost distributed on the acridine derivative donor, and the LUMO is almost distributed on the connected acceptor, successfully realizing the good separation of HOMO and LUMO, which is conducive to reducing the E ST value and improving the reverse intersystem crossing rate; and the electron cloud distribution on the HOMO of the molecule is on the entire acridine derivative donor, successfully realizing the conjugated delocalization of the HOMO, which is conducive to improving the radiation transition rate, ensuring a high reverse intersystem crossing rate and a high radiation transition rate.

[0085] Example 12 This example provides the absorption and emission spectra of the thermally activated delayed fluorescence material P1, P2, P5, P6, P21, P22.

[0086] The spectrum of this embodiment is as follows: Figures 7-12 As shown in the absorption spectrum, these six molecules exhibit a strong absorption peak in the 310-316 nm range, which can be attributed to the π-π* transition in the molecular backbone. A moderate absorption peak exists in the 331-358 nm range, which can be attributed to the intramolecular charge transfer absorption peak between the electron donor and acceptor, indicating a significant charge transfer effect. The fluorescence emission spectrum shows that P1, P2, and P5 have emission peaks of 548 nm, 544 nm, and 517 nm, respectively, exhibiting green light emission characteristics; while P6, P21, and P22 have emission peaks of 486 nm, 490 nm, and 485 nm, respectively, exhibiting sky-blue light emission characteristics. This indicates a blue shift occurred after adding a benzene ring for conjugation.

[0087] Device Example 1 This embodiment provides an organic electroluminescent device, the structure of which is as follows: ITO (95 nm) / HACT-CN (5 nm) / TAPC (20 nm) / TCTA (5 nm) / mCP (5 nm) / 25 wt% emitter: PPF (20 nm) / PPF (5 nm) / TmPyPb (40 nm) / LiF (1 nm) / Al (200 nm).

[0088] Wherein, "emitter" refers to the aforementioned acridine-derived thermally activated delayed fluorescent materials P1, P2, P10, and P17.

[0089] The structural formula of the material used is as follows:

[0090] The device fabrication process is as follows: ITO glass is sequentially subjected to ultrasonic treatment with acetone, isopropanol, and organic alkaline solution for a period of time, and finally rinsed with ultrapure water and dried in a 100 ℃ forced-air drying oven for 1 h. The dried ITO glass substrate is then treated with ultraviolet-ozone for 30 min.

[0091] The ITO substrate was transferred to a vacuum chamber, and a vacuum was drawn until the pressure was less than 10. -5 Pa, then sequentially evaporate the required functional layers to obtain the organic light-emitting diode device.

[0092] The device in this embodiment J-V-B The curves, the external quantum efficiency-luminosity curve, and the current efficiency-luminosity-power efficiency curve are shown below. Figures 13-15 As shown in Table 1, the specific results are as follows.

[0093] Table 1. Photophysical properties of molecules

[0094] Efficiency roll-off is the luminance at 1000 cd m -2 were measured.

[0095] The curves of P1, P2, P10 and P17 devices are similar, and each molecule has achieved good device efficiency and small efficiency roll-off.

[0096] Obviously, the above examples are merely illustrative for the sake of clarity, and are not intended to limit the embodiments. Based on the above description, other different forms of changes or variations can also be made by those of ordinary skill in the art. Here, it is not necessary and impossible to enumerate all the embodiments, and the changes or variations thus caused still fall within the protection scope of the present application.

Claims

1. A class of organic thermally activated delayed fluorescence material characterized by: An acridine derivative is used as a donor, and any electron-withdrawing group is used as an acceptor, and the nitrogen atom of the acridine derivative is directly connected to the acceptor, having the following general structure (1): ； In the formula (1), A is selected from substituted or unsubstituted C5-C60 aryl and substituted or unsubstituted C3-C60 heteroaryl; R 1 -R 19 each independently selected from the group consisting of hydrogen, sulfone, cyano, alkyl, alkoxy, substituted or unsubstituted C6-C60 aryl, substituted or unsubstituted C3-C60 heteroaryl, or R 1 -R 19 wherein adjacent substituents form a structure connected to each other, the structure connected to each other is C5-C60 aryl, C3-C60 heteroaryl; the substituents not forming the structure connected to each other are each independently selected from hydrogen, sulfone group, cyano, alkyl, alkoxy, substituted or unsubstituted C6-C60 aryl, substituted or unsubstituted C3-C60 heteroaryl. 2.The organic thermally activated delayed fluorescence material of claim 1, wherein A is an acceptor group, and the acceptor group A is selected from one of the following structures: 。 3.The organic thermally activated delayed fluorescence material of claim 1, wherein R 1 -R 19 the same or different, each independently selected from the group consisting of hydrogen, methyl, phenyl, pyridyl, carbazolyl, triazinyl, tolyl. 4.The organic thermally activated delayed fluorescence material of claim 1, wherein adjacent R 1 -R 19 are connected to each other to form one of the following structures: ； wherein is the point of attachment of the substituent. 5.The organic thermally activated delayed fluorescence material of claim 1, wherein The thermally activated delayed fluorescence material has the following structure: ； ； 。 6.The organic thermally activated delayed fluorescence material of claim 1, wherein The thermally activated delayed fluorescence material has any one of the following structures: 。 7. An organic electroluminescent device, characterized by The organic electroluminescent device comprises a first electrode, a second electrode, and a light-emitting layer between the first electrode and the second electrode, and the light-emitting layer comprises any one of the thermally activated delayed fluorescence materials according to any one of claims 1-6.

8. The organic electroluminescent device according to claim 7, characterized in that The light-emitting layer comprises the thermally activated delayed fluorescence material and an organic functional material, and the mass percentage of the thermally activated delayed fluorescence material is 0.01%-100%, and the rest is the organic functional material.

9. Use of the organic electroluminescent device according to claim 7 in an electronic device.

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