Thermally activated delayed fluorescent material, preparation method thereof, and organic light-emitting device

Abstract

The present application discloses a thermally activated delayed fluorescent material, a preparation method thereof, and an organic light-emitting device. The thermally activated delayed fluorescent material includes a compound having a structure shown in formula (I), which uses a well-planar conjugated system (X group) as an electron donor and a well-planar Y group as an electron acceptor. Thus, in three-dimensional space, a large torsion angle can be formed between the electron donor and the electron acceptor to reduce the exchange energy between the HOMO orbital and the LUMO orbital, thereby reducing the difference ΔEst between the singlet energy level and the triplet energy level, which is beneficial to improving the coupling light efficiency. The thermally activated delayed fluorescent material of the present application can be used to prepare the light-emitting layer of an organic light-emitting device, so that the maximum external quantum efficiency of the organic light-emitting device can reach 16.8%.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a thermally activated delayed fluorescent material, a preparation method thereof, and an organic light-emitting device. Background Art

[0002] Organic Light-Emitting Diode (OLED) display panels have attracted much attention due to their advantages such as self-luminescence, high contrast, fast response speed, low power consumption, high efficiency, and wide color gamut. They can be used in terminal products such as smartphones, tablets, and TVs. Due to their light weight, thin thickness, and strong bending resistance, they have become one of the ideal choices for manufacturing flexible display panels.

[0003] Currently, the luminescent materials used in OLEDs are generally either conventional fluorescent or phosphorescent materials. Both have drawbacks, limiting the further development and application of OLED technology. Conventional fluorescent materials can only utilize singlet excitons, resulting in a theoretical maximum internal quantum efficiency of 25%, which in turn leads to a low maximum external quantum efficiency and unsatisfactory luminescence efficiency. Phosphorescent materials can utilize both singlet and triplet excitons, with a theoretical maximum internal quantum efficiency of 100%. However, these materials cannot address the technical issues of low luminescence efficiency and short lifetime of blue phosphorescent light, and they require the use of costly rare metals to achieve high luminescence efficiency.

[0004] In recent years, thermally activated delayed fluorescence (TADF) materials based on triplet-singlet transitions have attracted increasing attention within the industry. Their theoretical maximum internal quantum efficiency can reach 100%, and they achieve high luminous efficiency without the use of rare precious metals, which helps reduce the manufacturing cost of OLED display panels. Therefore, TADF materials are organic light-emitting materials with industrial application value, and it is necessary to develop TADF materials that can be used in OLED display panels. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present application provides a thermally activated delayed fluorescent material, a preparation method thereof, and an organic light-emitting device.

[0006] In a first aspect, the present application provides a thermally activated delayed fluorescent material, wherein the thermally activated delayed fluorescent material comprises a compound having a structure represented by formula (I):

[0007]

[0008] wherein R1 and R2 are independently selected from hydrogen atom, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl or substituted heteroaryl;

[0009] The value of m is a positive integer in the range of 1 to 4, and the value of n is a positive integer in the range of 1 to 4;

[0010] R3, R4 and R5 are independently selected from a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, a heteroaryl group, a substituted heteroaryl group or an X group, and at least one of R3, R4 and R5 is an X group, and the X group is a condensed ring aromatic amine group or a condensed ring aromatic amine group having an alkyl substituent.

[0011] The X group is selected from the group represented by any one of the following structural formulas, or the X group is selected from the group represented by any one of the following structural formulas substituted by a methyl group, and * represents a connection site:

[0012]

[0013]

[0014] Furthermore, R1 and R2 are independently selected from an alkyl group having 1 to 12 carbon atoms, a substituted alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a substituted aryl group having 6 to 12 carbon atoms, a heteroaryl group having 6 to 12 carbon atoms, or a substituted heteroaryl group having 6 to 12 carbon atoms.

[0015] Furthermore, the thermally activated delayed fluorescent material includes one or more of the following compounds M1 to M30:

[0016]

[0017]

[0018] In a second aspect, the present application provides a method for preparing a thermally activated delayed fluorescent material, the preparation method comprising the following steps:

[0019] (1) providing reaction raw materials, wherein the reaction raw materials include compound a containing an X group, compound b containing a Y group, and a catalyst, and under the protection of a nitrogen atmosphere, the X group and the Y group are connected by a coupling reaction to obtain a reactant; and

[0020] (2) separating and purifying the reactants to obtain a thermally activated delayed fluorescent material;

[0021] Wherein, the thermally activated delayed fluorescent material includes a compound having a structure shown in formula (I):

[0022]

[0023] R1 and R2 are independently selected from hydrogen atom, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl or substituted heteroaryl;

[0024] The value of m is a positive integer in the range of 1 to 4, and the value of n is a positive integer in the range of 1 to 4;

[0025] R3, R4 and R5 are independently selected from a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, a heteroaryl group, a substituted heteroaryl group or an X group, and at least one of R3, R4 and R5 is an X group, and the X group is a condensed ring aromatic amine group or a condensed ring aromatic amine group having an alkyl substituent;

[0026] The Y group has a structure shown in formula (II), or the Y group is a group obtained by replacing the hydrogen atoms at one or more positions on the benzene ring where the connection site is located in formula (II) with a substituent:

[0027]

[0028] Wherein, the substituent is selected from hydrogen atom, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl or substituted heteroaryl.

[0029] Furthermore, the X group is selected from a group represented by any one of the following structural formulas, or the X group is selected from a group represented by any one of the following structural formulas obtained by substitution with a methyl group, and * represents a connection site:

[0030]

[0031] Furthermore, in the step S1, the molar ratio of the compound a containing an X group, the compound b containing a Y group, and the catalyst is (1.1-1.5):1:0.02.

[0032] In a third aspect, the present application provides an organic light-emitting device, comprising:

[0033] a first electrode;

[0034] a functional layer disposed on the first electrode; and

[0035] a second electrode, disposed on a side of the functional layer away from the first electrode;

[0036] Wherein, the functional layer includes a light-emitting layer, and the material of the light-emitting layer includes the thermally activated delayed fluorescent material as described in any one of the first aspects.

[0037] Furthermore, calculated as a percentage by mass, in the light-emitting layer, the mass of the activated delayed fluorescent material accounts for 1% to 50% of the total mass of the light-emitting layer.

[0038] The present application provides a thermally activated delayed fluorescent material, a preparation method thereof, and an organic light-emitting device. The thermally activated delayed fluorescent material uses a conjugated system (X group) with good planarity as an electron-donating group, and uses a Y group with good planarity as an electron acceptor, so that in three-dimensional space, a larger torsion angle can be formed between the electron donor and the electron acceptor to reduce the exchange energy between the HOMO orbital and the LUMO orbital, thereby reducing the difference ΔEst between the singlet energy level and the triplet energy level; in addition, since both the electron donor and the electron acceptor have good planar properties, when the thermally activated delayed fluorescent material is formed into a film, it is beneficial to promote the horizontal orientation of the material molecules, thereby improving the coupling light efficiency and further improving the maximum external quantum efficiency. The thermally activated delayed fluorescent material of the present application can be applied to organic light-emitting devices, and can be used to prepare the light-emitting layer of the organic light-emitting device, so that the maximum external quantum efficiency of the organic light-emitting device can reach 16.8%. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The following detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings will make the technical solutions and other beneficial effects of the present application apparent.

[0040] Figure 1 This is a schematic diagram of the structure of the organic light-emitting device provided in the examples of this application.

[0041] Figure 2 This is a schematic diagram of the process of preparing an organic light-emitting device provided in the examples of this application. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods and materials similar or equivalent to those described herein can be applied to the present invention. The preferred embodiments and materials described herein are for illustrative purposes only and are not intended to limit the scope of this application.

[0044] The embodiments of the present application aim to provide a thermally activated delayed fluorescent material, a preparation method thereof, and an organic light-emitting device. The thermally activated delayed fluorescent material can be applied to the light-emitting layer of the organic light-emitting device, thereby giving the organic light-emitting device ideal photoluminescence efficiency.

[0045] The thermally activated delayed fluorescent material includes a compound having a structure shown in formula (I):

[0046]

[0047] wherein R1 and R2 are independently selected from hydrogen atom, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl or substituted heteroaryl;

[0048] The value of m is a positive integer in the range of 1 to 4, and the value of n is a positive integer in the range of 1 to 4;

[0049] R3, R4 and R5 are independently selected from a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, a heteroaryl group, a substituted heteroaryl group or an X group, and at least one of R3, R4 and R5 is an X group, and the X group is a condensed ring aromatic amine group or a condensed ring aromatic amine group having an alkyl substituent.

[0050] As used in this application, "aliphatic hydrocarbon group" refers to a functional group containing only carbon and hydrogen atoms, which is the free radical remaining after the corresponding hydrocarbon loses a hydrogen atom. Aliphatic hydrocarbon group is a general term for all hydrocarbon groups except aromatic hydrocarbon groups, including saturated aliphatic hydrocarbon groups and unsaturated aliphatic hydrocarbon groups.

[0051] As used herein, "alkyl" refers to an aliphatic hydrocarbon group formed by losing a hydrogen atom from an alkane molecule, including branched or straight-chain saturated aliphatic hydrocarbon groups. "Alkyl" includes, but is not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, and sec-pentyl.

[0052] As used herein, "substituted alkyl" means that one or more hydrogen atoms on the alkyl group are optionally substituted with other groups except halogen atoms, and the other groups may be, for example, alkyl groups, and multiple degrees of substitution are allowed.

[0053] As used herein, "aryl" refers to an aromatic group containing only carbon atoms in the aromatic ring. "Aryl" includes, but is not limited to, phenyl, 1-naphthyl, 2-naphthyl, and biphenyl.

[0054] As used herein, "substituted aryl" means that one or more hydrogen atoms on the aryl group are optionally substituted by other groups except halogen atoms, and the other groups may be, for example, alkyl groups, and multiple degrees of substitution are allowed.

[0055] As used herein, "heteroaryl" refers to a stable five-membered or seven-membered aromatic ring containing at least one heteroatom selected from nitrogen, oxygen, or sulfur atoms, with the remaining ring atoms being carbon. "Heteroaryl" includes, but is not limited to, imidazolyl, pyrrolyl, pyridinyl, thiazolyl, pyrazolyl, thiazolyl, pyrimidinyl, and thienyl.

[0056] As used herein, "substituted heteroaryl" means that one or more hydrogen atoms on the heteroaryl group are optionally substituted by other groups other than halogen atoms, such as alkyl groups, and multiple degrees of substitution are allowed.

[0057] As used herein, "condensed ring aromatic amine group" refers to a group formed by condensed ring aromatic groups connected to imino groups.

[0058] In some embodiments of the present application, R1 and R2 are independently selected from an alkyl group having 1 to 12 carbon atoms, a substituted alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 12 carbon atoms, a substituted aryl group having 6 to 12 carbon atoms, a heteroaryl group having 6 to 12 carbon atoms, or a substituted heteroaryl group having 6 to 12 carbon atoms.

[0059] In some embodiments of the present application, R1 and R2 are the same group, for example, both R1 and R2 are hydrogen atoms, or both R1 and R2 are tert-butyl groups.

[0060] In some embodiments of the present application, no halogen atoms are contained at any position of the structure represented by formula (I), thereby avoiding the problem of fluorescence quenching due to the presence of halogen atoms and further preventing a negative impact on the luminous efficiency of the organic light-emitting device.

[0061] In some embodiments of the present application, the thermally activated delayed fluorescent material includes one or more compounds selected from the group consisting of compounds M1 to M30.

[0062] In some embodiments of the present application, the X group is selected from a group represented by any one of the following structural formulas, or the X group is selected from a group represented by any one of the following structural formulas substituted by a methyl group, and * represents a connection site:

[0063]

[0064]

[0065] It should be noted that, compared with the technical solution in which the X group is selected from the group represented by any of the above structural formulas, or the X group is selected from the group represented by any of the above structural formulas via methyl substitution, the technical solution in which the X group is selected from a carbazolyl group, a substituted carbazolyl group or a group represented by the structure shown in the following formula (III) has a poor effect. The reason is that the π conjugated system characteristics of the carbazolyl group, the substituted carbazolyl group or the group represented by the structure shown in formula (III) are not as good as the above groups or the above groups substituted by methyl; if the carbazolyl group, the substituted carbazolyl group or the group represented by the structure shown in formula (III) is used as an electron donor, the torsion angle formed between it and the Y group as the electron acceptor is small, thereby limiting the effect of reducing ΔEst; in addition, if the carbazolyl group, the substituted carbazolyl group or the group represented by the structure shown in formula (III) is used as an electron donor, due to its unsatisfactory planar performance, it is not conducive to the horizontal orientation of more material molecules after film formation, and the degree of improvement in light extraction efficiency is limited.

[0066]

[0067] In formula (III), Ar represents one or more fused-ring aromatic groups. When Ar represents multiple fused-ring aromatic groups, the multiple fused-ring aromatic groups are arranged linearly.

[0068] As used in this application, "plurality" means two or more.

[0069] As used herein, "carbazolyl" refers to a group having the structure shown in the following formula (IV):

[0070]

[0071] As used herein, "substituted carbazolyl" means that the hydrogen atoms at one or more positions on the benzene ring of the carbazolyl group are optionally substituted by other groups, such as alkyl groups, and multiple degrees of substitution are allowed.

[0072] The present application also provides an organic light emitting device, such as Figure 1 As shown, the organic light-emitting device 1 includes a first electrode 11, a functional layer 12, a second electrode 13 and a substrate 14, wherein the first electrode 11, the functional layer 12 and the second electrode 13 are sequentially arranged on the substrate 14, and the functional layer 12 is arranged between the first electrode 11 and the second electrode 13.

[0073] The materials of the first electrode 11 and the second electrode 13 can be pure metals, alloys or transparent metal oxides. The transparent metal oxides can be indium tin oxide (In2O3:Sn, ITO), indium zinc oxide (ZnO:In, IZO), gallium zinc oxide (ZnO:Ga, GZO), aluminum zinc oxide (ZnO:Al, AZO), etc. For example, the first electrode 11 is an anode, and the material of the first electrode 11 is ITO; the second electrode 13 is a cathode, and the material of the second electrode 13 is aluminum. It should be noted that the first electrode 11 can be selected as the anode and the second electrode 13 can be the cathode; the first electrode 11 can also be selected as the cathode and the second electrode 13 can be the anode, and no specific limitation is made here.

[0074] The substrate 14 may be a rigid substrate, such as a substrate made of glass, or a flexible substrate, such as a substrate made of polyimide.

[0075] Continue reading Figure 1 The functional layer 12 includes a hole injection layer 121, a hole transport layer 122, an electron blocking layer 123, a light emitting layer 124, a hole blocking layer 125, an electron transport layer 126 and an electron injection layer 127 arranged in sequence.

[0076] The hole injection layer 121 is disposed on the first electrode 11. As an example, the material of the hole injection layer 121 is 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HAT-CN, CAS No. 105598-27-4) and the thickness of the hole injection layer 121 is 10 nanometers.

[0077] The hole transport layer 122 is disposed on a side of the hole injection layer 121 away from the first electrode 11. As an example, the material of the hole transport layer 122 is TAPC (CAS No. 1174006-36-0), and the thickness of the hole transport layer 122 is 30 nanometers.

[0078] The electron blocking layer 123 is disposed on a side of the hole transport layer 122 away from the hole injection layer 121. As an example, the material of the electron blocking layer 123 is 9-(4-tert-butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole (CzSi, CAS No. 898546-82-2), and the thickness of the electron blocking layer 123 is 10 nanometers.

[0079] The light-emitting layer 124 is disposed on the side of the electron blocking layer 123 away from the hole transport layer 122. The material of the light-emitting layer 124 includes the thermally activated delayed fluorescent material described in the embodiments of the present application, and the thermally activated delayed fluorescent material may include one or more of compounds M1 to M30. Calculated by mass percentage, in the light-emitting layer, the mass of the activated delayed fluorescent material accounts for 1% to 50% of the total mass of the light-emitting layer. It is understood that the percentage of the mass of the activated delayed fluorescent material to the total mass of the light-emitting layer can be any value between 1% and 50%, for example, it can be an integer value such as 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or a non-integer value such as 2.5%, 7.5%, 16.5%, 20.2%, 30.7%, 46.3%.

[0080] As an example, calculated by mass percentage, the material of the light-emitting layer 124 is composed of 15% of the activated delayed fluorescent material and 85% of di[2-((oxy)diphenylphosphino)phenyl]ether (DPEPO, CAS No. 808142-23-6), and the thickness of the light-emitting layer 124 is 20 nanometers.

[0081] As an example, calculated by mass percentage, the material of the light-emitting layer 124 is composed of 1% of the activated delayed fluorescent material and 99% of di[2-((oxy)diphenylphosphino)phenyl]ether (DPEPO, CAS No. 808142-23-6), and the thickness of the light-emitting layer 124 is 20 nanometers.

[0082] As an example, calculated by mass percentage, the material of the light-emitting layer 124 is composed of 25% of the activated delayed fluorescent material and 75% of di[2-((oxy)diphenylphosphino)phenyl]ether (DPEPO, CAS No. 808142-23-6), and the thickness of the light-emitting layer 124 is 20 nanometers.

[0083] As an example, calculated by mass percentage, the material of the light-emitting layer 124 is composed of 50% of the activated delayed fluorescent material and 50% of di[2-((oxy)diphenylphosphino)phenyl]ether (DPEPO, CAS No. 808142-23-6), and the thickness of the light-emitting layer 124 is 20 nanometers.

[0084] The hole blocking layer 125 is disposed on a side of the light emitting layer 124 away from the electron blocking layer 123. As an example, the material of the hole blocking layer 125 is DPEPO, and the thickness of the hole blocking layer 125 is 10 nanometers.

[0085] The electron transport layer 126 is disposed on a side of the hole blocking layer 125 away from the hole blocking layer 125. As an example, the material of the electron transport layer 126 is 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi, CAS No. 192198-85-9), and the thickness of the electron transport layer 126 is 30 nanometers.

[0086] The electron injection layer 127 is disposed on the side of the electron transport layer 126 away from the hole blocking layer 125 and between the electron transport layer 126 and the second electrode 13. As an example, the material of the electron injection layer 127 is lithium fluoride and the thickness of the electron injection layer 127 is 1 nanometer.

[0087] The present invention also provides a method for preparing a thermally activated delayed fluorescent material, the method comprising the steps of:

[0088] (1) providing reaction raw materials, wherein the reaction raw materials include compound a containing an X group, compound b containing a Y group, and a catalyst, and under the protection of a nitrogen atmosphere, the X group and the Y group are connected by a coupling reaction to obtain a reactant; and

[0089] (2) Separating and purifying the reactants to obtain thermally activated delayed fluorescent materials.

[0090] The structure of the X group is as described above and will not be repeated here. The Y group has the structure shown in formula (II), or the Y group is a group obtained by replacing one or more hydrogen atoms on the benzene ring where the connection site is located with a substituent:

[0091]

[0092] Wherein, the substituent is selected from hydrogen atom, alkyl, substituted alkyl, aryl, substituted aryl, heteroaryl or substituted heteroaryl.

[0093] In addition, the type of catalyst is not specifically limited, and only needs to be able to catalyze the coupling reaction of compound a and compound b. In the embodiment of the present application, the catalyst is a palladium catalyst, for example, Pd2(dba)3 (CAS No. 60748-47-2) or Pd(PPh3)4 (CAS No. 14221-01-3). The molar ratio of compound a, compound b, and catalyst can be (1.1-1.5):1:0.02.

[0094] As an example, the molar ratio of compound a, compound b, and catalyst is 1.1:1:0.02.

[0095] As an example, the molar ratio of compound a, compound b, and catalyst is 1.25:1:0.02.

[0096] As an example, the molar ratio of compound a, compound b and catalyst is 1.5:1:0.02. The present application also provides a method for preparing an organic light-emitting device, for preparing Figure 2 The organic light emitting device shown in Figure 2 As shown, the method for preparing an organic light-emitting device specifically includes the following steps:

[0097] B a , providing a substrate, and forming a first electrode on the substrate.

[0098] As an example, the material of the first electrode is ITO, and the first electrode can be formed on the substrate using a photolithography process or an inkjet printing (IJP) process. The photolithography process is a conventional technical means known to those skilled in the art, which includes steps such as coating a photoresist, exposure, development, and drying.

[0099] B b 、For step B a The prepared substrate including the first electrode is cleaned.

[0100] As an example, the cleaning process includes the following steps: ultrasonic cleaning with 5% potassium hydroxide solution for 15 minutes, ultrasonic cleaning with pure water for 15 minutes, ultrasonic cleaning with isopropyl alcohol for 15 minutes, and drying in an oven for 1 hour.

[0101] B c , after step B b After cleaning, the substrate containing the first electrode is transferred to an ultraviolet ozone cleaning device for surface treatment for 15 minutes, and then transferred to a glove box.

[0102] B d , prepare a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer and a second electrode in sequence on a substrate containing a first electrode, then UV-curing and encapsulating, and finally baking at 80°C for 30 minutes to obtain an organic light-emitting device.

[0103] As an example, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a second electrode are sequentially prepared on a substrate including a first electrode using an evaporation film forming process. Before evaporation, the glove box is evacuated to 10 -7 Torr (1 torr equals 1 mmHg pressure = 133 Pa), then slowly increase the current value to slowly increase the rate to After the rate stabilizes, open the baffle and proceed with the evaporation operation.

[0104] The preparation method of the thermally activated delayed fluorescent material in the present application is described in detail below using the preparation method of compounds M1, M5, M16, M17 and M21 as examples. It should be noted that those skilled in the art can obtain the preparation methods of compounds M2, M3, M4, M8, M9, M10, M11, M12, M13, M14, M15, M18, M19, M20, M22, M23, M24, M25, M28, M29 and M30 according to the preparation methods of compounds M1, M5 and M21, and those skilled in the art can obtain the preparation methods of M6, M7, M26 and M27 according to the preparation methods of compounds M16 and M17.

[0105] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available, or can be prepared by methods known in the art, or those skilled in the art can easily know the preparation methods through existing technology and common knowledge. Among them, compound a and compound b can be prepared with reference to the literature, and the relevant literature involved is: (1) ACS Appl. Mater. Interfaces 2019, 11, 10758-10767; (2) Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2019), 7 (38), 11953-11963.

[0106] Example 1: Preparation of M1 compound as thermally activated delayed fluorescent material

[0107] The preparation method of compound M1 comprises the following steps:

[0108] B1.1. Take a 100 mL two-necked flask and add the following reaction materials: 2 mmol of compound b (borane bromide, CAS No. 2378498-93-0), 2.2 mmol of compound a (5-phenyl-5,11-dihydroindole[3,2-b]carbazole, CAS No. 1316311-27-9), and 4 mmol of sodium tert-butoxide (t-BuONa). Then, evacuate the flask and replace the atmosphere with nitrogen. Repeat this process three times to ensure that the flask is filled with nitrogen.

[0109] B1.2. Add 30 mL of toluene and 0.2 mmol of tri-tert-butylphosphine tetrafluoroborate (CAS No. 131274-22-1) to the two-necked flask prepared in step B1.1, and stir at 80°C for 15 min. Then, add 0.04 mmol of Pd2(dba)3 (CAS No. 60748-47-2) as a palladium catalyst, and react at 110°C for 12 h to obtain a reaction solution containing M1.

[0110] B1.3. Cool the reaction solution obtained in step B1.2 to room temperature, and then extract and separate the reaction solution with dichloromethane to obtain an extract containing M1;

[0111] B1.4. Subject the extract obtained in step B1.3 to silica gel column chromatography to obtain a purified solution containing M1, wherein the eluent is a mixture of n-hexane and dichloromethane in a volume ratio of 1:1;

[0112] B1.5. The purified solution from step B1.4 was subjected to rotary evaporation to remove the solvent, and then dried under vacuum at room temperature for 12 h. The product was collected and identified by liquid chromatography-mass spectrometry (HPLC-MS). The HPLC-MS test data was: molecular formula C 50 H 41 BN2O2, detection value [M+] + The calculated value is 712.33; 1HNMR (300 MHz, DMSO), δ(TMS, ppm): 8.55(d, 1H), 8.19(d, 5H), 7.94(d, 1H), 7.62-7.58(m, 4H), 7.55(s, 1H), 7.5(m, 5H), 7.40(s, 1H), 7.35-7.32(m, 3H), 7.20-7.16(m, 2H), 6.92(d, 2H), 6.83(s, 1H), 1.32(s, 18H), i.e., the product is M1 compound.

[0113] The preparation reaction formula of compound M1 is shown in the following formula (1.1):

[0114]

[0115] Example 2: Preparation of M5 compound as thermally activated delayed fluorescent material

[0116] The preparation method of M5 compound comprises the following steps:

[0117] B2.1. Add the following reaction materials to a 100 mL two-necked flask: 2 mmol of compound b (borane bromide, CAS No. 2378498-93-0), 2.2 mmol of compound a, and 4 mmol of sodium tert-butoxide (t-BuONa). Vacuum and replace with nitrogen three times to ensure that the flask is filled with nitrogen.

[0118] B2.2. To the two-necked flask prepared in step B2.1, 30 mL of toluene and 0.2 mmol of tri-tert-butylphosphine tetrafluoroborate (CAS No. 131274-22-1) were added and stirred at 80°C for 15 min. Then, 0.04 mmol of Pd2(dba)3 (CAS No. 60748-47-2) as a palladium catalyst was added. The mixture was reacted at 110°C for 12 h to obtain a reaction solution containing M5.

[0119] B2.3. Cool the reaction solution obtained in step B2.2 to room temperature, and then extract and separate the reaction solution with dichloromethane to obtain an extract containing M5;

[0120] B2.4. Subject the extract obtained in step B2.3 to silica gel column chromatography to obtain a purified solution containing M5, wherein the eluent is a mixture of n-hexane and dichloromethane in a volume ratio of 1:1;

[0121] B2.5. The purified solution from step B2.4 was subjected to rotary evaporation to remove the solvent, and then dried under vacuum at room temperature for 12 h. The product was collected and identified using HPLC-MS. The HPLC-MS test data showed the following molecular formula: 56 H 50 BNO2, detection value [M+] + The m / z value was 779.83, and the calculated value was 779.39; 1HNMR (300 MHz, DMSO), δ(TMS, ppm): 8.24(d, 2H), 8.19(s, 5H), 7.88(s, 2H), 7.74(d, 2H), 7.57-7.49(s, 5H), 7.38(m, 5H), 7.32(s, 2H), 6.92(d, 2H), 6.83(s, 2H), 1.69(s, 12H), 1.32(s, 18H), i.e., the product was compound M5.

[0122] The preparation reaction formula of compound M5 is shown in the following formula (2.1):

[0123]

[0124] Example 3: Preparation of M21 compound as thermally activated delayed fluorescent material

[0125] The preparation method of M21 compound comprises the following steps:

[0126] B3.1. Take a 100 mL two-necked flask and add the following reaction materials: 2 mmol of compound b (borane bromide, CAS No. 1800321-94-1), 2.2 mmol of a carbazole derivative (5-phenyl-5,11-dihydroindole[3,2-b]carbazole, CAS No. 1316311-27-9), and 4 mmol of sodium tert-butoxide (t-BuONa). Evacuate the flask and replace the atmosphere with nitrogen. Repeat this process three times to ensure that the flask is filled with nitrogen.

[0127] B3.2. To the two-necked flask prepared in step B3.1, 30 mL of toluene and 0.2 mmol of tri-tert-butylphosphine tetrafluoroborate (CAS No. 131274-22-1) were added and stirred at 80°C for 15 min. Then, 0.04 mmol of Pd2(dba)3 (CAS No. 60748-47-2) as a palladium catalyst was added. The mixture was reacted at 110°C for 12 h to obtain a reaction solution containing M21.

[0128] B3.3. Cool the reaction solution obtained in step B3.2 to room temperature, and then extract and separate the reaction solution with dichloromethane to obtain an extract containing M21;

[0129] B3.4. Subject the extract obtained in step B3.3 to silica gel column chromatography to obtain a purified solution containing M21, wherein the eluent is a mixture of n-hexane and dichloromethane in a volume ratio of 1:1;

[0130] B3.5. The purified solution from step B3.4 was subjected to rotary evaporation to remove the solvent, and then dried under vacuum at room temperature for 12 h. The product was collected and identified using HPLC-MS. The HPLC-MS test data showed the following molecular formula: 42 H 25 BN2O2, detection value [M+] + The calculated value is 600.20; 1HNMR (300MHz, DMSO), δ(TMS, ppm): 8.55(d, 1H), 8.19(d, 1H), 7.94(m, 1H), 7.71-7.62(m, 5H), 7.58-7.50(m, 6H), 7.40-7.35(m, 4H), 7.20-7.00(m, 4H), 6.86(d, 1H), i.e., the product is compound M21.

[0131] The preparation reaction formula of compound M21 is shown in the following formula (3.1):

[0132]

[0133] Example 4: Preparation of M16 compound as thermally activated delayed fluorescent material

[0134] The preparation method of the M16 compound comprises the following steps:

[0135] B4.1. Add the following reaction materials to a 100 mL two-necked flask: 2 mmol of compound b, 2.2 mmol of compound a, and 0.04 mmol of palladium catalyst, Pd(PPh3)4 (CAS No. 14221-01-3). Vacuum and replace with nitrogen three times to ensure that the flask is filled with nitrogen.

[0136] B4.2. Add 30 mL of toluene and 25 mL of 2 mol / L Na2CO3 solution to the two-necked flask prepared in step B4.1. React at 110°C for 12 h to obtain a reaction solution containing M16.

[0137] B4.3. Cool the reaction solution obtained in step B4.2 to room temperature, and then extract and separate the reaction solution with dichloromethane to obtain an extract containing M16;

[0138] B4.4. Subject the extract obtained in step B4.3 to silica gel column chromatography to obtain a purified solution containing M17, wherein the eluent is a mixture of n-hexane and dichloromethane in a volume ratio of 1:1;

[0139] B4.5. The purified solution from step B4.4 was subjected to rotary evaporation to remove the solvent, and then dried under vacuum at room temperature for 12 h. The product was collected and identified using HPLC-MS. The HPLC-MS test data showed the following molecular formula: 45 H 36 BO2, detection value [M+] + The calculated value is 633.28; 1HNMR (300 MHz, DMSO), δ (TMS, ppm): 7.71 (m, 2H), 7.66 (s, 2H), 7.35 (m, 2H), 7.17 (m, 2H), 7.07-7.00 (m, 10H), 1.69 (s, 18H), i.e., the product is compound M16.

[0140] The preparation reaction formula of compound M16 is shown in the following formula (3.1):

[0141]

[0142] Example 5: Preparation of M17 compound as thermally activated delayed fluorescent material

[0143] The preparation method of the M17 compound comprises the following steps:

[0144] B5.1. Add the following reaction materials to a 100 mL two-necked flask: 2 mmol of compound b, 2.2 mmol of compound a, and 0.04 mmol of palladium catalyst, Pd(PPh3)4 (CAS No. 14221-01-3). Vacuum and replace with nitrogen three times to ensure that the flask is filled with nitrogen.

[0145] B5.2. Add 30 mL of toluene and 25 mL of 2 mol / L Na2CO3 solution to the two-necked flask prepared in step B5.1. React at 110°C for 12 h to obtain a reaction solution containing M17.

[0146] B5.3. Cool the reaction solution obtained in step B5.2 to room temperature, and then extract and separate the reaction solution with dichloromethane to obtain an extract containing M17;

[0147] B5.4. Subject the extract obtained in step B5.3 to silica gel column chromatography to obtain a purified solution containing M17, wherein the eluent is a mixture of n-hexane and dichloromethane in a volume ratio of 1:1;

[0148] B5.5. The purified solution from step B5.4 was subjected to rotary evaporation to remove the solvent, and then dried under vacuum at room temperature for 12 hours. The product was collected and identified using HPLC-MS. The HPLC-MS test data showed the following molecular formula: 42 H 30 BNO2, detection value [M+] + The m / z value was 591.24, and the calculated value was 591.52; 1HNMR (300 MHz, DMSO), δ(TMS, ppm): 8.45(m, 1H), 8.09(m, 2H), 7.84(s, 2H), 7.71(d, 2H), 7.45(m, 1H), 7.35(m, 2H), 7.24(m, 1H), 7.07-6.98(m, 8H), 1.69(s, 12H), i.e., the product was compound M17.

[0149] The preparation reaction formula of compound M17 is shown in the following formula (3.1):

[0150]

[0151] Test example: Performance test of organic light-emitting devices

[0152] In this test example, a total of 31 organic light-emitting devices participated in the performance test, and the 31 organic light-emitting devices corresponded to devices T1 to T30 and devices D1. The only difference between the 31 organic light-emitting devices is that the thermally activated delayed fluorescent materials used to prepare the light-emitting layer are different. Among them, the thermally activated delayed fluorescent materials used in devices T1 to T30 correspond to compounds M1 to M30, respectively. The thermally activated delayed fluorescent material used in the D1 device has been disclosed in the prior art, and its structural formula is shown in the following formula (V):

[0153]

[0154] The structural composition of 31 organic light-emitting devices is as follows Figure 1 As shown, the material of the hole injection layer 121 is HAT-CN, with a thickness of 10 nanometers; the material of the hole transport layer 122 is TAPC, with a thickness of 30 nanometers; the material of the electron blocking layer 123 is CzSi, with a thickness of 10 nanometers; calculated by mass percentage, the material of the light-emitting layer 124 is composed of 15% activated delayed fluorescent material and 85% DPEPO, and the thickness of the light-emitting layer 124 is 20 nanometers; the material of the hole blocking layer 125 is DPEPO, with a thickness of 10 nanometers; the material of the electron transport layer 126 is TPBi, with a thickness of 30 nanometers; the material of the electron injection layer 127 is lithium fluoride, with a thickness of 1 nanometer.

[0155] The T1 to T30 devices and the D1 device were tested for luminous performance using an IV-L test system. The equipment used for luminous performance testing was an F-star CS2000A. The test structure is detailed in Table 1 below:

[0156] Table 1 Luminescence performance test results of all organic light-emitting devices in the experimental example

[0157]

[0158]

[0159] As shown in Table 1, the maximum external quantum efficiency of devices T1 through T30 is higher than that of the D1 device, demonstrating that the thermally activated delayed fluorescent materials of the present invention can further improve light extraction efficiency compared to the existing thermally activated delayed fluorescent material (Compound D1). The maximum external quantum efficiency of devices T1 through T30 is above 11%, with the T3 device having the highest maximum external quantum efficiency, reaching 16.8%, which is 1.5 times that of the D1 device.

[0160] The thermally activated delayed fluorescent materials used in T1 to T30 devices use a well-planar conjugated system (X group) as the electron donor and a well-planar Y group as the electron acceptor. As a result, in three-dimensional space, a larger torsion angle can be formed between the electron donor and the electron acceptor to reduce the exchange energy between the HOMO orbital and the LUMO orbital, thereby reducing the difference ΔEst between the singlet energy level and the triplet energy level. In addition, since both the electron donor and the electron acceptor have good planar properties, when the thermally activated delayed fluorescent material is formed into a film, it is beneficial to promote the horizontal orientation of the material molecules, thereby improving the coupling light efficiency and further improving the maximum external quantum efficiency.

[0161] The above is a detailed introduction to the thermally activated delayed fluorescent material, preparation method, and organic light-emitting device provided in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present application. Those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein with equivalents. However, these modifications or replacements do not deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An organic light-emitting device, characterized in that: The organic light emitting device comprises: a first electrode; a functional layer disposed on the first electrode; and a second electrode, disposed on a side of the functional layer away from the first electrode; The functional layer includes a light-emitting layer, and the material of the light-emitting layer includes a thermally activated delayed fluorescent material. Calculated by mass percentage, in the light-emitting layer, the mass of the thermally activated delayed fluorescent material accounts for 1% to 50% of the total mass of the light-emitting layer. The thermally activated delayed fluorescent material is a compound having a structure shown in formula (I): (Ⅰ) wherein R1 and R2 are independently selected from a hydrogen atom or an alkyl group having 1 to 12 carbon atoms; The value of m is a positive integer in the range of 1 to 4, and the value of n is a positive integer in the range of 1 to 4; R3, R4 and R5 are independently selected from a hydrogen atom or an X group, and at least one of R3, R4 and R5 is an X group, and the X group is selected from a group represented by any one of the following structural formulas: ； ； ； 。 2. The organic light-emitting device according to claim 1, wherein The thermally activated delayed fluorescent material is selected from one or more of the following compounds: ； ； ； 。

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