9, 9-bifluorene-fluorene indole derivative and electroluminescent device thereof

Abstract

The invention belongs to the technical field of organic luminescent materials and semiconductors, and provides a 9, 9-bifluorene-based indole derivative and an electroluminescent device thereof, and the structural formula of the 9, 9-bifluorene-based indole derivative is # imgabs0 #. The 9, 9-bifluorene-fluorene indole derivative provided by the invention is used as a luminescent layer material for preparing an electroluminescent device, so that the luminescent property of the electroluminescent device can be effectively improved, and the service life of the electroluminescent device is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of organic light-emitting materials and semiconductors, and specifically relates to a 9,9-difluoroindole derivative and an electroluminescent device thereof. Background Art

[0002] In recent years, organic light emitting diodes (OLED) have become a hot research direction in the field of lighting and display due to their excellent properties such as self-luminescence, high brightness, high contrast, see-through, wearable, foldable, low energy consumption, wide viewing angle, and low temperature resistance.

[0003] OLED devices are usually composed of functional layers such as anode, cathode, hole transport layer (HTL), emission material layer (EML), electron transport layer (ETL), etc. The selection and matching of hole transport layer, emission layer and other functional layer materials will have a significant impact on the current efficiency, driving voltage, luminous color purity, luminous brightness and life of OLED devices. Therefore, exploring functional layer materials with higher performance is still a key task in the development of the current OLED industry.

[0004] Chinese invention patent CN106187861B discloses a spirobifluorenoindole derivative, a preparation method and application thereof, but the current efficiency and life of an OLED device prepared based on the derivative are not ideal.

[0005] Therefore, in order to meet people's higher requirements for OLED devices, the field is in urgent need of developing higher performance functional layer materials. Summary of the invention

[0006] In order to solve the above problems of the prior art, the present invention provides a 9,9-difluoroindole derivative and an electroluminescent device thereof. The comprehensive performance of the electroluminescent device based on the 9,9-difluoroindole derivative, such as current efficiency and life span, are improved.

[0007] The present invention is achieved through the following technical solutions: In a first aspect, the present invention provides a 9,9-difluoroindole derivative, wherein the structural formula of the 9,9-difluoroindole derivative is shown in formula (1):

[0008] Wherein, L is selected from substituted or unsubstituted C6~C 40 Aryl and substituted or unsubstituted C4~C 40The heteroaryl group, L and the main structure are bonded by a single bond; the heteroatom in the heteroaryl group includes at least one of O, S and N, and the main structure is .

[0009] Preferably, the substituted or unsubstituted C6~C 40 The aryl group refers to the C6~C 40 The aryl group may be further substituted by a substituent or may not be substituted by a substituent; when the C6~C 40 When the aryl group is substituted by a substituent, the substituent is selected from phenyl, naphthyl, biphenyl, phenanthryl, benzo[9,10]phenanthryl, methyl, 9,9-dimethyl-9,10-dihydroanthracenyl and fluoranthenyl.

[0010] Preferably, the substituted or unsubstituted C4~C 40 The heteroaryl group refers to the C4~C 40 The heteroaryl group may be further substituted by a substituent or may not be substituted by a substituent; when the C4~C 40 When the heteroaryl is substituted by a substituent, the substituent is selected from phenyl, biphenyl, naphthyl, phenanthryl, anthracenyl, methyl, ethyl, isopropyl, tert-butyl, carbonyl, benzofuranyl, naphtho[2,1-B]benzofuranyl, fluorenyl, xanthyl, thioanthenyl, 1-methylpiperidin-4-enyl, N,N-dimethyl-3-enyl, carbazolyl, N-phenylcarbazolyl, dibenzothienyl, dibenzofuranyl, deuterated phenyl, methylthio, methoxy, cyano, ethoxycyano, tolyl, xylyl, ethylphenyl, cyclohexylphenyl, pyridyl, cyclopropyl, pyrimidinyl, methylsulfonyl, morpholinyl, and phenanthroline.

[0011] As used herein, the term "aryl" refers to an all-carbon monocyclic or fused polycyclic (ie, rings that share adjacent pairs of carbon atoms) group having a conjugated π electron system.

[0012] In the present invention, the term "heteroaryl" refers to a general term for groups in which one or more aromatic carbon atoms or non-aromatic carbon atoms in an aromatic group are replaced by heteroatoms, and the heteroaryl group may be a monocyclic heteroaryl group, a polycyclic heteroaryl group or a condensed-ring heteroaryl group.

[0013] Preferably, in the 9,9-difluoroindole derivatives, the L is selected from one of the following groups L1-1 to L1-19:

[0014] In the groups L1-1 to L1-19, " indicates the position where L is bonded to the main structure, wherein groups L1-9, L1-10, L1-12, L1-13, L1-14, L1-16, L1-17, L1-18 and L1-19 are bonded to the main structure only through one " ” is bonded to the main structure.

[0015] Preferably, in the 9,9-difluoroindole derivatives, L is selected from one of the following groups L2-1 to L2-32:

[0016] In the groups L2-1 to L2-32, " represents the position where L is bonded to the main structure, wherein the groups L2-4, L2-7, L2-8, L2-9, L2-10, L2-18, L2-19, L2-21, L2-24, L2-27 and L2-28 are bonded to the main structure only through one " ” is bonded to the main structure.

[0017] Preferably, in the 9,9-difluoroindole derivatives, the L is selected from one of the following groups L3-1 to L3-89:

[0018] In the groups L3-1 to L3-89, " indicates the position where L is bonded to the main structure, wherein groups L3-4, L3-5, L3-19, L3-45, L3-78, L3-79, L3-87 and L3-88 are bonded to the main structure only through one " ” is bonded to the main structure.

[0019] Preferably, the 9,9-difluoroindole derivative is selected from one of the following compounds H1-1 to H3-99:

[0020] In a second aspect, the present invention provides an electroluminescent device, comprising a cathode, an anode and an organic layer located between the cathode and the anode, wherein the organic layer comprises a hole transport layer, a light-emitting layer and an electron transport layer, wherein the hole transport layer is located between the anode and the light-emitting layer, and the electron transport layer is located between the cathode and the light-emitting layer; and the components of the light-emitting layer include a 9,9-difluoroindole derivative as shown in formula (1).

[0021] Preferably, the hole transport layer comprises a 9,9-difluoroindole derivative as shown in formula (1).

[0022] In some embodiments of the present invention, in the hole transport layer, L of the 9,9-difluoroindole derivative is selected from the group L2-1 to L2-32. The 9,9-difluoroindole derivative in which L is selected from the group L2-1 to L2-32 has an extended conjugated π electron system, which is beneficial to hole transport and luminescence, and also contains an electron donating group, which can enhance the hole injection and transport capabilities.

[0023] Preferably, the components of the light-emitting layer include a host light-emitting material (Host) and a guest light-emitting material (Dopant); the host light-emitting material includes a 9,9-difluoroindole derivative as shown in formula (1), and the guest light-emitting material can be selected from , , and One of them.

[0024] In some embodiments of the present invention, the host luminescent material comprises a first host luminescent material and a second host luminescent material, and the first host luminescent material and the second host luminescent material are both 9,9-difluoroindole derivatives shown in formula (1); in the first host luminescent material, L of the 9,9-difluoroindole derivative is selected from the group L2-1 to L2-32; in the second host luminescent material, L of the 9,9-difluoroindole derivative is selected from the group L3-1 to L3-89. The 9,9-difluoroindole derivative in which L is selected from the group L2-1 to L2-32 is used as a hole transport type host luminescent material, and contains an electron donating group (such as a group containing atoms such as O, S, and N with a lone electron pair), which improves the hole injection and transport capabilities. L is selected from 9,9-difluoroindole derivatives of groups L3-1~L3-89 as electron-transporting main luminescent materials, containing electron-deficient groups (such as cyano, carbonyl, triazine, pyrimidine, pyridine, phenanthroline, pyridazine, pyrazine, etc.), which are conducive to electron transport.

[0025] Preferably, the components of the light-emitting layer include a host light-emitting material and a guest light-emitting material; the guest light-emitting material includes a 9,9-difluoroindole derivative as shown in formula (1), and the host light-emitting material is selected from and One of; or the host light-emitting material includes a first host light-emitting material and a second host light-emitting material; The first host luminescent material is selected from any one of the following RH1-1 to RH1-4:

[0026] The second host luminescent material is selected from any one of the following RH2-1 to RH2-4: .

[0027] In some embodiments of the present invention, in the guest luminescent material, L of the 9,9-difluoroindole derivative is selected from the group L3-1 to L3-89. The 9,9-difluoroindole derivative in which L is selected from the group L3-1 to L3-89 has both an electron-donating group and an electron-withdrawing group, and thus can be used as a thermally activated delayed fluorescence (TADF) material, and the TADF material can be used as a guest luminescent material.

[0028] Preferably, the mass fraction of the guest luminescent material of the present invention accounts for 0.1% to 3.0% of the mass fraction of the entire luminescent layer.

[0029] Preferably, the electroluminescent device of the present invention further comprises a hole injection layer (HIL), an electron blocking layer (EBL), a hole blocking layer (HBL) and an electron injection layer (EIL); the hole injection layer is located between the anode and the hole transport layer, the electron blocking layer is located between the hole transport layer and between the light-emitting layer, the hole blocking layer is located between the light-emitting layer and the electron transport layer, and the electron injection layer is located between the electron transport layer and the cathode.

[0030] As the anode in the electroluminescent device, in order to enable holes to be smoothly injected into the organic layer, the anode material is preferably a material with a large work function. Specific examples of the anode material that can be used in the present invention include: metals such as vanadium, chromium, copper, zinc and gold or their alloys, oxides such as zinc oxide, aluminum oxide or tin dioxide, and conductive polymers such as polypyrrole and polyaniline.

[0031] The hole injection layer, hole transport layer, electron blocking layer, hole blocking layer, electron transport layer and electron injection layer described in the present invention are made of corresponding materials with excellent cost performance in the industry, and the compatibility between the layers needs to be determined through a series of tests and screening processes.

[0032] Preferably, the material of the hole injection layer in the present invention is preferably MoO3.

[0033] Preferably, the hole transport layer in the present invention is selected from one of the following materials: .

[0034] Preferably, the material of the electron blocking layer in the present invention is selected from one of the following materials: .

[0035] Preferably, the material of the hole blocking layer in the present invention is selected from one of the following materials: .

[0036] Preferably, the electron transport layer in the present invention is selected from one of the following materials: .

[0037] As the cathode, in order to facilitate the electron injection into the organic layer, the cathode material is preferably a material with a small work function. Specific examples of cathode materials that can be used in the present invention include metals such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin and lead, or their alloys.

[0038] The electroluminescent device of the present invention may further include a substrate on the outer side of the anode, and a covering protection layer (CPL) on the outer side of the cathode.

[0039] As a substrate, it is required to have high mechanical strength, excellent thermal stability, excellent water resistance, and excellent transparency.

[0040] As a covering protective layer, it can improve the refractive index of the cathode surface and increase the light extraction rate; preferably .

[0041] The hole injection layer, hole transport layer, electron blocking layer, light emitting layer, hole blocking layer, electron transport layer and electron injection layer can be prepared by various means or methods such as vacuum thermal evaporation, spin coating, printing, etc.

[0042] In a third aspect, the present invention provides a method for preparing the above-mentioned electroluminescent device, wherein an anode is adhered to a substrate after pretreatment and cleaning, and then a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer and an electron injection layer of set thickness are sequentially evaporated under low temperature conditions, and then a cathode and a covering protective layer are sputtered at low temperature, and finally the test device is packaged using conventional device test packaging means to obtain an electroluminescent device.

[0043] In a fourth aspect, the present invention provides a display panel, wherein the display panel comprises the electroluminescent device as described above.

[0044] Compared with the prior art, the present invention has the following beneficial effects: In the 9,9-difluoroindole derivatives provided by the present invention, the 9,9-difluoroindole structure is obtained by connecting two fluorene groups with an unsaturated double bond, so the 9,9-difluoroindole structure has a higher degree of unsaturation, a larger conjugated system, a larger electron delocalization range, a stronger conjugation effect, and a stronger absorption spectrum; at the same time, because the 9,9-difluoroindole structure is obtained by connecting two fluorene groups with an unsaturated double bond, it has good flexibility and adaptability, so that the conjugated system is relatively more stretched, the intermolecular interaction is stronger, and it shows good stability (i.e., improved life) and consistency in the charge transfer process. When used as an organic photoelectric material, it can achieve efficient charge transfer, which is beneficial to improving the comprehensive performance of electroluminescent devices.

[0045] The electroluminescent device provided by the present invention adopts 9,9-difluoroindole derivatives as the luminescent layer material, which can effectively improve the luminescent performance of the electroluminescent device and prolong the service life of the electroluminescent device.

[0046] Furthermore, the electroluminescent device uses 9,9-difluoroindole derivatives as hole transport layer materials, which can further reduce the starting voltage and improve the overall performance of the electroluminescent device. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 is a schematic structural diagram of the electroluminescent device described in an embodiment of the present invention; Figure 2 This is the NMR spectrum of compound H1-5 prepared in Preparation Example 1 of the present invention; Figure 3 This is the NMR spectrum of compound H1-19 prepared in Preparation Example 2 of the present invention; Figure 4 This is the NMR spectrum of compound H2-25 prepared in Preparation Example 3 of the present invention; Figure 5 This is the NMR spectrum of compound H2-43 prepared in Preparation Example 4 of the present invention; Figure 6 This is the NMR spectrum of compound H3-2 prepared in Preparation Example 5 of the present invention; Figure 7 This is the NMR spectrum of compound H3-37 prepared in Preparation Example 6 of the present invention.

[0049] Description of reference numerals: 1-substrate, 2-anode, 3-hole injection layer, 4-hole transport layer, 5-electron blocking layer, 6-light-emitting layer, 7-hole blocking layer, 8-electron transport layer, 9-electron injection layer, 10-cathode, 11-covering protective layer. DETAILED DESCRIPTION

[0050] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0051] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples, unless otherwise specified, are conventional commercial products, and their specifications are conventional specifications in the art.

[0052] The synthesis process of the 9,9-difluoroindole derivatives of the present invention is described as follows.

[0053] Synthesis of intermediate M1:

[0054] Step 1: Operation process: Under inert atmosphere, add 9H-fluorene (166g, 1.0mol) and 2.5L of tetrahydrofuran (THF) to a 10L three-necked flask, start stirring, cool the reaction solution to below -78°C, add 2.5mol / L n-butyllithium (n-BuLi) (400mL, 1.0mol) dropwise, and continue to stir the reaction solution for 1h after the addition is complete. Slowly add 800mL of THF solution of 1-bromo-9-fluorenone (272g, 1.05mol). After the addition is complete, stir the reaction for 1h. Transfer the reaction solution to room temperature and continue to react for 2h until the reaction is complete. After the reaction is completed, the reaction system is concentrated at low temperature to remove most of the THF, 3 L of dichloromethane is added to dilute, and the mixture is washed with 3 L of water. The organic phase is dried and concentrated to obtain a residue, and the residue is purified by silica gel column chromatography (dichloromethane / petroleum ether) to obtain an intermediate M1-1, weighing 306 g, with a yield of 72%, a purity of 98% by HPLC (High Performance Liquid Chromatography), and a molecular weight of 425.1 by LC-MS (Liquid Chromatograph-Mass Spectrometer).

[0055] Step 2: Operation process: Add intermediate M1-1 (298 g, 0.7 mol) and 2.5 L of a mixed solution of sulfuric acid and acetic acid (V 硫酸 :V 乙酸 =2:8), stirring was started, the reaction solution was heated to 60°C, and the reaction was continued for 1 hour until the reaction was completed. The reaction solution was cooled to room temperature, 3L of water was added, and the reaction solution was extracted with 6L of ether for 3 times, each time with 2L, and the organic phases were combined. The organic phases were dried, filtered, and concentrated to obtain a residue, which was purified by silica gel column chromatography (dichloromethane / petroleum ether) to obtain intermediate M1-2, weighing 205g, with a yield of 72%, HPLC purity of 98%, and LC-MS showing a molecular weight of 407.0.

[0056] Step 3: Operation process: Under an inert atmosphere, add intermediate M1-2 (204g, 0.5mol), 2-nitrobenzeneboronic acid pinacol ester (131g, 0.53mol), potassium carbonate (138g, 1.0mol), 500mL deionized water, 2.0L THF into a 5L three-necked flask, start stirring, add Pd(PPh3)4 (11.6g, 0.01mol), heat the system to 80°C, and reflux for 10h until the reaction is complete. Wash the reaction solution with water and separate the liquids. Collect the filtrate after the organic phase passes through a diatomaceous earth funnel. Concentrate the filtrate under reduced pressure to obtain a solid crude product. The solid crude product is purified by silica gel column chromatography (dichloromethane / petroleum ether) to obtain intermediate M1-3, weighing 178g, with a yield of 79%, HPLC content of 99%, and LC-MS molecular weight of 450.2.

[0057] Step 4: Operation process: Under an inert atmosphere, add intermediate M1-3 (157 g, 0.35 mol), 2.5 L o-dichlorobenzene, and triphenylphosphine (PPh3) (230 g, 0.875 mol) into a 5L three-necked flask, start stirring, and heat the reaction solution to 180°C and reflux for 10 hours until the reaction is complete. The reaction solution is cooled to room temperature, and the solvent is concentrated under reduced pressure to obtain a solid crude product. The solid crude product is purified by silica gel column chromatography (ethyl acetate / petroleum ether) to obtain intermediate M1, weighing 133 g, with a yield of 91%, HPLC purity of 99%, and LC-MS showing a molecular weight of 418.2.

[0058] Those skilled in the art can refer to the structural formula of formula (1) and the following specific examples to prepare compounds H1-1 to H3-99 in combination with intermediate M1.

[0059] Preparation Example 1 Synthesis of compound H1-5:

[0060] Operation process: Under inert atmosphere, add intermediate M1 (4.2 g, 0.01 mol), 1-chloro-4-phenylnaphthalene (3.7 g, 0.0105 mol), and 50 mL of toluene into a 100 mL three-necked flask, stir until the solution is clear, add Pd2(dba)3 (0.18 g, 0.2 mmol), Am-phos ([(4-(N,N-dimethylamino)phenyl]di-tert-butylphosphine) (0.13 g, 0.5 mmol), sodium tert-butoxide (3.8 g, 0 .04mmol), the reaction solution was heated to 120℃ and the reaction was continued for 10h. After the reaction was completed, diatomaceous earth was used for hot filtration, the filtrate was cooled to room temperature, purified water was added for washing, the organic phase was retained after separation, the aqueous phase was extracted with ethyl acetate, the organic phases were combined, dried over anhydrous magnesium sulfate, concentrated, and passed through a column (dichloromethane / petroleum ether) to obtain compound H1-5, weighing 4.7g, with a yield of 76%, HPLC content of 99%, and LC-MS showing a molecular weight of 620.2. The NMR spectrum of compound H1-5 is shown as follows Figure 2 shown.

[0061] H NMR spectrum data of compound H1-5: 1 H NMR (500 MHz, CD3OD) δ 8.95 (s, 1H), 8.55(s, 1H), 8.12 (d, J = 39.6 Hz, 4H), 7.89 (s, 1H), 7.79 (s, 2H), 7.60 – 7.29 (m,18H), 7.13 (d, J = 25.0 Hz, 2H). Preparation Example 2 Synthesis of compound H1-19:

[0062] Operation process: Referring to the synthesis process of compound H1-5, 1-chloro-4-phenylnaphthalene was replaced with 4-bromophenanthrene (2.7 g, 0.0105 mol) to obtain compound H1-19, weighing 4.4 g, with a yield of 74%, HPLC content of 99%, and LC-MS showing a molecular weight of 594.3. The NMR spectrum of compound H1-19 is shown in Figure 3 shown.

[0063] H NMR spectrum data of compound H1-19: 1 H NMR (500 MHz, CD3OD) δ 8.98 (dd, J = 7.3,1.6 Hz, 1H), 8.55 (dd, J = 7.4, 1.5 Hz, 1H), 8.35 (dd, J= 7.4, 1.5 Hz, 1H), 8.20– 8.12 (m, 3H), 7.94 – 7.83 (m, 3H), 7.80 – 7.72 (m, 2H), 7.65 (dtd, J = 26.2,7.4, 1.5 Hz, 2H), 7.59 – 7.54 (m, 3H), 7.53 – 7.48 (m, 2H), 7.46 – 7.39 (m,7H), 7.13 (dtd, J = 26.0, 7.5, 1.5 Hz, 2H). Preparation Example 3 Synthesis of compound H2-25:

[0064] Operation process: Referring to the synthesis process of compound H1-5, 1-chloro-4-phenylnaphthalene was replaced with 2-bromo-9,9′-spirodioxanthene (4.5 g, 0.0105 mol) to obtain compound H2-25, weighing 5.6 g, with a yield of 73%, HPLC content of 99%, and LC-MS showing a molecular weight of 764.3. The NMR spectrum of compound H2-25 is shown in Figure 4 shown.

[0065] H NMR spectrum data of compound H2-25: 1 H NMR (500 MHz, CD3OD) δ 8.55 (s, 1H), 8.16 (s, 3H), 7.74 (s, 1H), 7.58 (d, J = 10.0 Hz, 4H), 7.51 (d, J = 10.0 Hz, 2H), 7.43(d, J = 10.0 Hz, 7H), 7.31 (s, 3H), 7.22 – 7.14 (m, 7H), 7.11 (d, J = 5.0 Hz,2H), 7.00 (s, 3H). Preparation Example 4 Synthesis of compound H2-43:

[0066] Operation process: Referring to the synthesis process of compound H1-5, 1-chloro-4-phenylnaphthalene was replaced with 8-chloronaphtho[1,2-b]benzofuran (2.65 g, 0.0105 mol) to obtain compound H2-43, weighing 4.8 g, with a yield of 76%, HPLC content of 99%, and LC-MS showing a molecular weight of 634.3. The NMR spectrum of compound H2-43 is shown in Figure 5 shown.

[0067] H NMR spectrum data of compound H2-43: 1 H NMR (500 MHz, CD3OD) δ 8.55 (s, 1H), 8.37 (s, 1H), 8.16 (s, 3H), 8.02 (s, 1H), 7.84 (s, 2H), 7.64 (s, 1H), 7.58 (d, J =10.0 Hz, 4H), 7.54 – 7.46 (m, 4H), 7.43 (d, J = 10.0 Hz, 7H), 7.23 (s, 1H), 7.13 (d, J = 25.0 Hz, 2H). Preparation Example 5 Synthesis of compound H3-2:

[0068] Operation process: Referring to the synthesis process of compound H1-5, 1-chloro-4-phenylnaphthalene was replaced with 2-chloro-4-(2-naphthyl)-6-phenyl-1,3,5-triazine (3.3 g, 0.0105 mol) to obtain compound H3-2, weighing 5.0 g, with a yield of 72%, HPLC content of 99%, and LC-MS showing a molecular weight of 699.3. The NMR spectrum of compound H3-2 is shown as follows Figure 6 shown.

[0069] H NMR spectrum data of compound H3-2: 1 H NMR (500 MHz, CD3OD) δ 9.09 (s, 1H), 8.52(d, J = 30.0 Hz, 2H), 8.36 (s, 2H), 8.16 (s, 4H), 8.08 (s, 1H), 8.00 (s, 1H),7.65 – 7.39 (m, 17H), 7.13 (d, J = 25.0 Hz, 2H). Preparation Example 6 Synthesis of compound H3-37:

[0070] Operation process: Referring to the synthesis process of compound H1-5, 1-chloro-4-phenylnaphthalene was replaced with 2-cyano-4-bromopyrimidine (1.9 g, 0.0105 mol) to obtain compound H3-37, weighing 3.7 g, with a yield of 71%, HPLC content of 99%, and LC-MS showing a molecular weight of 521.2. The NMR spectrum of compound H3-37 is shown in Figure 7 shown.

[0071] H NMR spectrum data of compound H3-37: 1 H NMR (500 MHz, CD3OD) δ 9.25 (s, 1H), 8.55 (s, 1H), 8.31 (s, 1H), 8.16 (s, 3H), 7.61 – 7.48 (m, 5H), 7.43 (d, J = 10.0 Hz,7H), 7.13 (d, J = 25.0 Hz, 2H). According to the structural information of the light-emitting layer of the electroluminescent device given in Table 1, the electroluminescent devices of Examples 1 to 44 and Comparative Examples 1 to 5 were prepared.

[0072] The structural schematic diagrams of the electroluminescent devices in the embodiments and comparative examples of the present invention are shown in FIG. Figure 1 As shown, it includes a substrate 1, an anode 2, a hole injection layer 3, a hole transport layer 4, an electron blocking layer 5, a light-emitting layer 6, a hole blocking layer 7, an electron transport layer 8, an electron injection layer 9, a cathode 10 and a covering protective layer 11.

[0073] Example 1 Electroluminescent device containing compound H1-7 The electroluminescent device containing compound H1-7 in this embodiment includes polyethylene terephthalate (PET) plastic, indium tin oxide (ITO) conductive glass, MoO3, HT-2, EB-2, light-emitting layer, HB-1, ET-2, LiF, Al-Mg (Al:Mg=9:1) and CPL in order from anode to cathode; the material used for CPL is ; Among them, the light-emitting layer is composed of H1-7 and Ir(ppy)3 with a mass ratio of 99:1.

[0074] The method for preparing the electroluminescent device containing the compound H1-7 comprises the following steps: 1. Use 1.5 mm PET plastic as substrate 1 and 0.15 mm ITO conductive glass as anode 2, and use alkaline washing, pure water washing, drying, and ultraviolet-ozone washing in sequence to remove organic residues on the surface of PET plastic and ITO conductive glass.

[0075] 2. Attach a layer of ITO conductive glass to PET plastic, and use a vacuum evaporation device to evaporate 20nm thick MoO3 as a hole injection layer 3, and then evaporate 110nm thick HT-2 as a hole transport layer 4, and then evaporate 30nm thick EB-2 as an electron blocking layer 5. Continue to evaporate 60nm thick luminescent layer 6 formed by compound H1-7 (main luminescent material) and Ir(ppy)3 (guest luminescent material) with a mass ratio of 99:1 on EB-2, and then evaporate 110nm thick HT-2 as a hole transport layer 4, and then evaporate 110nm thick EB-2 as an electron blocking layer 5 ... A 10 nm thick HB-1 is continuously evaporated on the optical layer 6 as a hole blocking layer 7, and then a 30 nm thick ET-2 is continuously evaporated as an electron transport layer 8, and then a 16 nm thick LiF is continuously evaporated on the electron transport layer 8 as an electron injection layer 9. After the electron injection layer 9 is evaporated, a 10 nm thick Al-Mg (Al:Mg=9:1) alloy is sputtered as a cathode 10 by low-temperature sputtering, and finally a 40 nm thick CPL is continuously evaporated on the cathode 10 as a covering protective layer 11.

[0076] 3. MoO3, HT-2, EB-2, light-emitting layer 6, HB-1, ET-2 and LiF are vacuum packaged to prepare an electroluminescent device.

[0077] Embodiment 2 to Embodiment 18 The difference from Example 1 is that Examples 2 to 18 respectively use compounds H1-18, H1-25, H2-31, H2-32, H1-13, H1-14, H2-1, H2-2, H2-4, H2-5, H2-9, H2-12, H2-27, H2-28, H2-30, H2-35, and H2-41 as the main luminescent materials of the luminescent layer 6.

[0078] Embodiment 19 to Embodiment 40 The difference from Example 1 is that Examples 19 to Example 40 all use BH-1 as the main luminescent material of the luminescent layer 6, and Examples 19 to Example 40 respectively use compounds H3-10, H3-43, H3-90, H3-4, H3-13, H3-14, H3-20, H3-21, H3-26, H3-28, H3-34, H3-50, H3-56, H3-58, H3-66, H3-69, H3-75, H3-76, H3-80, H3-86, H3-95, and H3-99 as the guest luminescent materials of the luminescent layer 6.

[0079] Embodiment 41 to Embodiment 44 The difference from Example 1 is that in the light-emitting layer 6 of Example 41 to Example 44, compounds H2-21, H2-25, H2-33, and H2-36 are used as the first host light-emitting materials, and compound H3-90 is used as the second host light-emitting material, and the mass ratio of the first host light-emitting material, the second host light-emitting material, and the guest light-emitting material is 40:60:1. At the same time, the materials of the hole transport layers corresponding to Examples 41 to 44 are compounds H2-21, H2-25, H2-33, and H2-36, respectively.

[0080] Comparative Example 1 The difference from Example 1 is that in the light-emitting layer 6, HB-1 is used as the main light-emitting material.

[0081] The structure of the electroluminescent device of Comparative Example 1 is: PET substrate / ITO / MoO3 (20nm) / HT-2 (110nm) / EB-2 (30nm) / BH-1:Ir(ppy)3=99:1 (60nm) / HB-1 (10nm) / ET-2 (30nm) / LiF (16nm) / Al:Mg=9:1 (10nm) / CPL (40nm).

[0082] Comparative Example 2 The difference from Example 1 is that in the light-emitting layer 6, BH-2 is used as the main light-emitting material.

[0083] The structure of the electroluminescent device of Comparative Example 2 is: PET substrate / ITO / MoO3 (20nm) / HT-2 (110nm) / EB-2 (30nm) / BH-2:Ir(ppy)3=99:1 (60nm) / HB-1 (10nm) / ET-2 (30nm) / LiF (16nm) / Al:Mg=9:1 (10nm) / CPL (40nm).

[0084] Comparative Example 3 The difference from Example 1 is that in the light-emitting layer 6 , BH-1 is used as the host light-emitting material and C545T is used as the guest light-emitting material.

[0085] The structure of the electroluminescent device of Comparative Example 3 is: PET substrate / ITO / MoO3 (20nm) / HT-2 (110nm) / EB-2 (30nm) / BH-1:C545T=99:1 (60nm) / HB-1 (10nm) / ET-2 (30nm) / LiF (16nm) / Al:Mg=9:1 (10nm) / CPL (40nm).

[0086] Comparative Example 4 The difference from Example 1 is that in the light-emitting layer 6, BH-1 is used as the main light-emitting material, and compound 41 in Chinese invention patent CN106187861B is used. As a guest luminescent material.

[0087] The structure of the electroluminescent device of Comparative Example 4 is: PET substrate / ITO / MoO3 (20nm) / HT-2 (110nm) / EB-2 (30nm) / BH-1: Compound 41 = 99:1 (60nm) / HB-1 (10nm) / ET-2 (30nm) / LiF (16nm) / Al:Mg = 9:1 (10nm) / CPL (40nm).

[0088] Comparative Example 5 The difference from Example 1 is that in the light-emitting layer 6, RH1-3 is selected as the first host light-emitting material, RH2-2 is selected as the second host light-emitting material, and the mass ratio of the first host light-emitting material, the second host light-emitting material and the guest light-emitting material is 40:60:1.

[0089] The structure of the electroluminescent device of Comparative Example 5 is: PET substrate / ITO / MoO3(20nm) / HT-2(110nm) / EB-2(30nm) / RH1-3:RH2-2:Ir(ppy)3=40:60:1(60nm) / HB-1(10nm) / ET-2(30nm) / LiF(16nm) / Al:Mg=9:1(10nm) / CPL(40nm).

[0090] The electroluminescent devices in the above examples and comparative examples were prepared into samples of 30 mm×30 mm, and the anode and cathode were connected using a driving circuit known in the industry, and various luminescence performance indicators were tested. The test results are shown in Table 2.

[0091] It can be seen from the test results in Table 2 that, compared with Comparative Examples 1 to 4, the electroluminescent devices prepared by using the preferred 9,9-difluoroindole derivatives of the present invention in Examples 1 to 44 have obvious advantages in comprehensive luminous efficiency. It can be seen from Examples 1 to 18 that the electroluminescent device prepared by using the preferred compound of the present invention as the main luminescent material has a current efficiency of about 50% and a service life LT95 of about 40% relative to Comparative Example 1. It can be seen from Examples 19 to 40 that the electroluminescent device prepared by using the preferred compound of the present invention as the guest luminescent material has a current efficiency of about 45% and a service life LT95 of about 80% relative to Comparative Example 3; relative to Comparative Example 4, the current efficiency is increased by about 80% and the service life LT95 is extended by about 100%. It can be seen from Examples 41 to 44 that the electroluminescent device prepared by using the preferred compound of the present invention as both a dual-host luminescent material and a hole transport layer material has a significantly lower starting voltage and a service life LT95 of nearly 2 times relative to Comparative Example 5.

[0092] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A 9,9-difluoroindole derivative, characterized in that: The structural formula of the 9,9-difluoroindole derivative is shown in formula (1): Formula (1) Wherein, L is selected from substituted or unsubstituted C6~C 40 Aryl and substituted or unsubstituted C4~C 40 The bonding mode of L to the main structure is single bond; the heteroatom in the heteroaryl group includes at least one of O, S and N; the main structure is .

2. The 9,9-difluoroindole derivative according to claim 1, characterized in that: The L is selected from one of the following groups L1-1 to L1-19: In the groups L1-1 to L1-19, " " indicates the position where L is bonded to the main structure, wherein groups L1-9, L1-10, L1-12, L1-13, L1-14, L1-16, L1-17, L1-18 and L1-19 are bonded to the main structure only through one " ” is bonded to the main structure.

3. The 9,9-difluoroindole derivative according to claim 1, characterized in that: The L is selected from one of the following groups L2-1 to L2-32: In the groups L2-1 to L2-32, " " indicates the position where L is bonded to the main structure, wherein the groups L2-4, L2-7, L2-8, L2-9, L2-10, L2-18, L2-19, L2-21, L2-24, L2-27, and L2-28 are bonded to the main structure only through one" ” is bonded to the main structure.

4. The 9,9-difluoroindole derivative according to claim 1, characterized in that: The L is selected from one of the following groups L3-1 to L3-89: In the groups L3-1 to L3-89, " " indicates the position where L is bonded to the main structure, wherein groups L3-4, L3-5, L3-19, L3-45, L3-78, L3-79, L3-87 and L3-88 are bonded to the main structure only through one" ” is bonded to the main structure.

5. An electroluminescent device, characterized in that: It comprises a cathode, an anode and an organic layer located between the cathode and the anode, wherein the organic layer comprises a hole transport layer, a light-emitting layer and an electron transport layer, wherein the hole transport layer is located between the anode and the light-emitting layer, and the electron transport layer is located between the cathode and the light-emitting layer; and the components of the light-emitting layer include the 9,9-difluoroindole derivatives according to any one of claims 1 to 4.

6. The electroluminescent device according to claim 5, characterized in that The components of the hole transport layer include the 9,9-difluoroindole derivative according to any one of claims 1 to 4.

7. The electroluminescent device according to claim 5, characterized in that The components of the light-emitting layer include a host light-emitting material and a guest light-emitting material; the host light-emitting material includes the 9,9-difluoroindole derivative according to any one of claims 1 to 4.

8. The electroluminescent device according to claim 5, characterized in that The components of the light-emitting layer include a host light-emitting material and a guest light-emitting material; the guest light-emitting material includes the 9,9-difluoroindole derivative according to any one of claims 1 to 4.

9. An electroluminescent device, characterized in that: It includes a cathode, an anode and an organic layer located between the cathode and the anode, wherein the organic layer includes a hole transport layer, a light-emitting layer and an electron transport layer, wherein the hole transport layer is located between the anode and the light-emitting layer, and the electron transport layer is located between the cathode and the light-emitting layer; the components of the light-emitting layer include a host light-emitting material and a guest light-emitting material; the host light-emitting material includes a first host light-emitting material and a second host light-emitting material, wherein the first host light-emitting material includes the 9,9-difluoroindole derivative described in claim 3, and the second host light-emitting material includes the 9,9-difluoroindole derivative described in claim 4.

10. An electroluminescent device, characterized in that: It comprises a cathode, an anode and an organic layer located between the cathode and the anode, wherein the organic layer comprises a hole transport layer, a light-emitting layer and an electron transport layer, wherein the hole transport layer is located between the anode and the light-emitting layer, and the electron transport layer is located between the cathode and the light-emitting layer; the components of the light-emitting layer comprise a main light-emitting material and a guest light-emitting material; and the guest light-emitting material comprises the 9,9-difluoroindole derivative described in claim 4.

Images