A 9,9'-bianthrylindole derivative and an electroluminescent device thereof

Abstract

The present invention belongs to the technical field of organic light-emitting materials and semiconductors, and provides a 9,9-bis(indenofluorenyl)indole derivative and an electroluminescent device thereof. The structural formula of the 9,9-bis(indenofluorenyl)indole derivative is as follows. The 9,9-bis(indenofluorenyl)indole derivative provided by the present invention is used as a light-emitting layer material to prepare an electroluminescent device, which can effectively improve the luminescence performance of the electroluminescent device and extend the service life of the electroluminescent device.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic light-emitting materials and semiconductors, and particularly relates to a 9,9-bis(indenofluorenyl)indole derivative and an electroluminescent device thereof. Background Art

[0002] In recent years, organic light-emitting diodes (OLEDs) have become a popular research direction in the fields of lighting and display due to their excellent properties such as self-luminescence, high brightness, high contrast, transparency, wearability, foldability, low power consumption, wide viewing angle, and low-temperature resistance.

[0003] An OLED device usually consists of functional layers such as an anode, a cathode, a hole transport layer (HTL), an emission material layer (EML), and an electron transport layer (ETL). The selection and combination of materials for the hole transport layer, the emission layer, and other functional layers have a significant impact on the current efficiency, driving voltage, emission color purity, emission brightness, and lifespan of the OLED device. Therefore, exploring functional layer materials with higher performance remains a key task in the current development of the OLED industry.

[0004] Chinese Patent CN106187861B discloses a spirobifluorene-indole derivative, its preparation method and application, but the current efficiency and lifespan of the OLED device based on this derivative are not ideal.

[0005] Therefore, in order to meet the higher requirements for OLED devices, there is an urgent need in this field to develop functional layer materials with higher performance. Summary of the Invention

[0006] To solve the problems of the above-mentioned prior art, the present invention provides a 9,9-bis(indenofluorenyl)indole derivative and an electroluminescent device thereof, and the comprehensive performance such as the current efficiency and lifespan of the electroluminescent device based on the 9,9-bis(indenofluorenyl)indole derivative is improved.

[0007] The present invention is achieved through the following technical solutions:

[0008] In the first aspect, the present invention provides a 9,9-bis(indenofluorenyl)indole derivative, and the structural formula of the 9,9-bis(indenofluorenyl)indole derivative is shown as formula (1):

[0009]

[0010] wherein, L is selected from substituted or unsubstituted C6~C 40aryl and substituted or unsubstituted C4-C 40 heteroaryl, and the bonding mode of L to the main structure is single-bond bonding; the heteroatoms in the heteroaryl include at least one of O, S, and N, and the main structure is .

[0011] Preferably, the substituted or unsubstituted C6-C 40 aryl means that the C6-C 40 aryl can be further substituted by substituents or not; when the C6-C 40 aryl is substituted by substituents, the substituents are selected from phenyl, naphthyl, biphenyl, phenanthryl, benzo[9,10]phenanthryl, methyl, 9,9-dimethyl-9,10-dihydroanthryl, and fluoranthenyl.

[0012] Preferably, the substituted or unsubstituted C4-C 40 heteroaryl means that the C4-C 40 heteroaryl can be further substituted by substituents or not; when the C4-C 40 heteroaryl is substituted by substituents, the substituents are selected from phenyl, biphenyl, naphthyl, phenanthryl, anthryl, methyl, ethyl, isopropyl, tert-butyl, carbonyl, benzofuranyl, naphtho[2,1-b]benzofuranyl, fluorenyl, xanthenyl, thioxanthenyl, 1-methylpiperidin-4-yl, N,N-dimethyl-3-enyl, carbazolyl, N-phenylcarbazolyl, dibenzothiophenyl, dibenzofuranyl, deuterated phenyl, methylthio, methoxy, cyano, acetonitrile, tolyl, xylyl, ethylphenyl, cyclohexylphenyl, pyridyl, cyclopropyl, pyrimidinyl, methanesulfonyl, morpholinyl, phenanthrolineyl.

[0013] In the present invention, the term "aryl" refers to a monocyclic or fused polycyclic (i.e., rings sharing adjacent carbon atom pairs) group having a conjugated π-electron system composed entirely of carbon atoms.

[0014] In the present invention, the term "heteroaryl" refers to the general name of a group obtained by replacing one or more aryl ring carbon atoms or non-aryl ring carbon atoms in an aryl group with heteroatoms, and the heteroaryl can be a monocyclic heteroaryl, a polycyclic heteroaryl, or a fused-ring heteroaryl.

[0015] Preferably, in the 9,9-bisindenylindole derivatives, the L is selected from one of the following groups L1-1 to L1-19:

[0016]

[0017] Among the groups L1-1 to L1-19, " ” indicates the position where L is bonded to the main body structure, wherein the groups L1-9, L1-10, L1-12, L1-13, L1-14, L1-16, L1-17, L1-18 and L1-19 are each bonded to the main body structure only through one “ ”.

[0018] Preferably, in the 9,9-bis(indenyl)indole derivatives, L is selected from one of the following groups L2-1 to L2-32:

[0019]

[0020] In the groups L2-1 to L2-32, “ ” indicates the position where L is bonded to the main body 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 each bonded to the main body structure only through one “ ”.

[0021] Preferably, in the 9,9-bis(indenyl)indole derivatives, L is selected from one of the following groups L3-1 to L3-89:

[0022]

[0023] In the groups L3-1 to L3-89, “ ” indicates the position where L is bonded to the main body structure, wherein the groups L3-4, L3-5, L3-19, L3-45, L3-78, L3-79, L3-87 and L3-88 are each bonded to the main body structure only through one “ ”.

[0024] Preferably, the 9,9-bis(indenyl)indole derivatives are selected from one of the following compounds H1-1 to H3-99:

[0025]

[0026] 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. The organic layer includes a hole transport layer, a light-emitting layer, and an electron transport layer. 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 component of the light-emitting layer includes a 9,9-bis(indenofluorenyl)indole derivative represented by formula (1).

[0027] Preferably, the component of the hole transport layer includes a 9,9-bis(indenofluorenyl)indole derivative represented by formula (1).

[0028] In some embodiments of the present invention, in the hole transport layer, L of the 9,9-bis(indenofluorenyl)indole derivative is selected from the groups L2-1 to L2-32. The 9,9-bis(indenofluorenyl)indole derivative in which L is selected from the groups L2-1 to L2-32 has an extended conjugated π-electron system, which is beneficial to hole transport and light emission. At the same time, it also contains an electron-donating group, which can improve the hole injection and transport ability.

[0029] Preferably, the component of the light-emitting layer includes a host light-emitting material (Host) and a guest light-emitting material (Dopant); the host light-emitting material includes a 9,9-bis(indenofluorenyl)indole derivative represented by formula (1), and the guest light-emitting material can be selected from those with excellent performance , , and one of the following.

[0030] In some embodiments of the present invention, the host luminescent material includes a first host luminescent material and a second host luminescent material, and both the first host luminescent material and the second host luminescent material are 9,9-bis(indenyl)indole derivatives represented by formula (1); in the first host luminescent material, L of the 9,9-bis(indenyl)indole derivative is selected from the groups L2-1 to L2-32; in the second host luminescent material, L of the 9,9-bis(indenyl)indole derivative is selected from the groups L3-1 to L3-89. The 9,9-bis(indenyl)indole derivative in which L is selected from the groups L2-1 to L2-32 is used as a hole-transporting host luminescent material and contains an electron-donating group (such as a group containing atoms such as O, S, N with lone electron pairs), which improves the hole injection and transport ability. The 9,9-bis(indenyl)indole derivative in which L is selected from the groups L3-1 to L3-89 is used as an electron-transporting host luminescent material and contains an electron-withdrawing group (such as a cyano group, a carbonyl group, a triazine group, a pyrimidine group, a pyridine group, a phenanthroline group, a pyridazine group, a pyrazine group, etc.), which is beneficial to electron transport.

[0031] Preferably, the components of the light-emitting layer include a host luminescent material and a guest luminescent material; the guest luminescent material includes a 9,9-bis(indenyl)indole derivative represented by formula (1), and the host luminescent material is selected from and one of the following; or the host luminescent material includes a first host luminescent material and a second host luminescent material;

[0032] The first host luminescent material is selected from any one of the following RH1-1 to RH1-4:

[0033]

[0034] The second host luminescent material is selected from any one of the following RH2-1 to RH2-4:

[0035] .

[0036] In some embodiments of the present invention, in the guest luminescent material, L of the 9,9-bis(indenyl)indole derivative is selected from the groups L3-1 to L3-89. The 9,9-bis(indenyl)indole derivative in which L is selected from the groups L3-1 to L3-89 has both an electron-donating group and an electron-withdrawing group, so it can be used as a thermally activated delayed fluorescence (TADF) material, and the TADF material can be used as a guest luminescent material.

[0037] Preferably, the mass fraction of the host luminescent material in the entire luminescent layer of the present invention is 0.1% to 3.0%.

[0038] Preferably, the electroluminescent device of the present invention further includes a hole injection layer (Hole Injection Layer, HIL), an electron blocking layer (Electron Blocking Layer, EBL), a hole blocking layer (Hole Blocking Layer, HBL), and an electron injection layer (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 the luminescent layer, the hole blocking layer is located between the luminescent layer and the electron transport layer, and the electron injection layer is located between the electron transport layer and the cathode.

[0039] As the anode in the electroluminescent device, generally 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, alumina, or tin dioxide, and conductive polymers such as polypyrrole and polyaniline.

[0040] In the present invention, the hole injection layer, hole transport layer, electron blocking layer, hole blocking layer, electron transport layer, and electron injection layer are selected from corresponding materials with excellent cost performance in the industry. The compatibility between each layer needs to be determined through a series of testing and screening processes.

[0041] Preferably, the material of the hole injection layer in the present invention is preferably MoO3.

[0042] Preferably, the hole transport layer in the present invention is selected from one of the following materials:

[0043] 。

[0044] Preferably, the material of the electron blocking layer in the present invention is selected from one of the following materials:

[0045] 。

[0046] Preferably, the material of the hole blocking layer in the present invention is selected from one of the following materials:

[0047] 。

[0048] Preferably, the electron transport layer in the present invention is selected from one of the following materials:

[0049] 。

[0050] As the cathode, generally in order to facilitate the injection of electrons into the organic layer, the cathode material is preferably a material with a small work function. Specific examples of the cathode material 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 alloys thereof.

[0051] In the electroluminescent device of the present invention, a substrate may further be provided outside the anode, and a covering protection layer (CPL) may further be provided outside the cathode.

[0052] As the substrate, it is required to have high mechanical strength, excellent thermal stability, excellent waterproofness, and excellent transparency.

[0053] As the covering protection layer, it can improve the refractive index of the cathode surface and increase the light extraction rate; preferably .

[0054] 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.

[0055] In a third aspect, the present invention provides a method for preparing the above-mentioned electroluminescent device. After pre-treatment and cleaning, the anode is adhered to the substrate, and then the hole injection layer, hole transport layer, electron blocking layer, light-emitting layer, hole blocking layer, electron transport layer, and electron injection layer with set thicknesses are sequentially evaporated under low-temperature conditions, and then the cathode and the covering protection layer are sputtered under low temperature. Finally, the test device is encapsulated by conventional device test encapsulation means to obtain the electroluminescent device.

[0056] In a fourth aspect, the present invention provides a display panel, and the display panel includes the above-mentioned electroluminescent device.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] In the 9,9-bifluorene-fused indole derivatives provided by the present invention, the 9,9-bifluorene structure is obtained by connecting two fluorene groups with unsaturated double bonds. Therefore, the 9,9-bifluorene 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, since the 9,9-bifluorene structure is obtained by connecting two fluorene groups with unsaturated double bonds, it has good flexibility and adaptability, making the conjugated system relatively more extended, with strong intermolecular interactions, showing good stability (i.e., increased lifespan) and consistency during the charge transport process. When used as an organic optoelectronic material, it can achieve efficient charge transport, which is beneficial to improving the comprehensive performance of the electroluminescent device.

[0059] The electroluminescent device provided by the present invention uses a 9,9-bifluorenoindole derivative as the light-emitting layer material, which can effectively improve the light-emitting performance of the electroluminescent device and extend the service life of the electroluminescent device.

[0060] Furthermore, the electroluminescent device uses a 9,9-bifluorenoindole derivative as the hole transport layer material, which can further reduce the turn-on voltage and improve the comprehensive performance of the electroluminescent device. Description of the Drawings

[0061] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0062] Figure 1 It is a schematic structural diagram of the electroluminescent device described in the embodiment of the present invention;

[0063] Figure 2 It is the NMR spectrum of compound H1-5 prepared in Preparation Example 1 of the present invention;

[0064] Figure 3 It is the NMR spectrum of compound H1-19 prepared in Preparation Example 2 of the present invention;

[0065] Figure 4 It is the NMR spectrum of compound H2-25 prepared in Preparation Example 3 of the present invention;

[0066] Figure 5 It is the NMR spectrum of compound H2-43 prepared in Preparation Example 4 of the present invention;

[0067] Figure 6 It is the NMR spectrum of compound H3-2 prepared in Preparation Example 5 of the present invention;

[0068] Figure 7 It is the NMR spectrum of compound H3-37 prepared in Preparation Example 6 of the present invention.

[0069] Description of the Reference Numerals:

[0070] 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 protection layer. Detailed Embodiments

[0071] The following specific examples illustrate the implementation modes of the present invention. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0072] Conventional instrument equipment in the art is used in the following examples. For the experimental methods without specific conditions noted in the following examples, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. All kinds of raw materials used in the following examples, unless otherwise stated, are commercially available products with conventional specifications in the art.

[0073] The synthesis process of the 9,9-bis(indenyl)indole derivatives described in the present invention is introduced as follows.

[0074] Synthesis of intermediate M1:

[0075]

[0076] Step 1:

[0077] Operation process: Under an inert atmosphere, 9H-fluorene (166 g, 1.0 mol) and 2.5 L of tetrahydrofuran (THF) were added to a 10 L three-necked flask. Stirring was started, and the reaction solution was cooled to below -78 °C. 2.5 mol / L of n-butyllithium (n-BuLi) (400 mL, 1.0 mol) was added dropwise. After the addition was completed, the reaction solution was stirred for 1 h. An 800 mL THF solution of 1-bromo-9-fluorenone (272 g, 1.05 mol) was slowly added dropwise. After the addition was completed, the reaction was stirred for 1 h. The reaction solution was transferred to room temperature and the reaction continued for 2 h until the reaction was complete. After the reaction was completed, most of the THF was concentrated at low temperature in the reaction system. 3 L of dichloromethane was added for dilution, and it was washed with 3 L of water. The organic phase was dried and concentrated to obtain a residue. The residue was purified by silica gel column chromatography (dichloromethane / petroleum ether) to obtain intermediate M1-1, weighing 306 g, with a yield of 72%, HPLC (High Performance Liquid Chromatography) purity of 98%, and LC-MS (Liquid Chromatograph-Mass Spectrometer) showing a molecular weight of 425.1.

[0078] Step 2:

[0079] Operation process: Intermediate M1-1 (298 g, 0.7 mol) and a 2.5 L mixed solution of sulfuric acid and acetic acid (V 硫酸:V 乙酸 (2:8), start stirring, heat the reaction solution to 60 °C, and continue the reaction for 1 h until the reaction is complete. Cool the reaction solution to room temperature, add 3 L of water, extract the reaction solution with 6 L of diethyl ether in 3 portions, 2 L each time. Combine the organic phases, dry, filter, and concentrate the organic phases to obtain a residue. The residue is purified by silica gel column chromatography (dichloromethane / petroleum ether) to obtain intermediate M1-2, weighing 205 g, with a yield of 72%, HPLC purity of 98%, and LC-MS showing a molecular weight of 407.0.

[0080] Step 3:

[0081] Procedure: Under an inert atmosphere, add intermediate M1-2 (204 g, 0.5 mol), 2-nitrophenylboronic acid pinacol ester (131 g, 0.53 mol), potassium carbonate (138 g, 1.0 mol), 500 mL of deionized water, and 2.0 L of THF into a 5 L three-necked flask. Start stirring, add Pd(PPh3)4 (11.6 g, 0.01 mol), heat the system to 80 °C, and reflux for 10 h until the reaction is complete. Wash the reaction solution with water and separate the layers. Collect the filtrate after passing the organic phase through a diatomaceous earth funnel. Concentrate the filtrate under reduced pressure to dryness 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 178 g, with a yield of 79%, HPLC content of 99%, and LC-MS molecular weight of 450.2.

[0082] Step 4:

[0083] Procedure: Under an inert atmosphere, add intermediate M1-3 (157 g, 0.35 mol), 2.5 L of o-dichlorobenzene, and triphenylphosphine (PPh3) (230 g, 0.875 mol) into a 5 L three-necked flask. Start stirring, heat the reaction solution to 180 °C and reflux for 10 h until the reaction is complete. Cool the reaction solution to room temperature, concentrate the solvent 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.

[0084] Those skilled in the art can refer to the structural formula of the above formula (1) and the following specific examples, and combine intermediate M1 to prepare compounds H1-1 to compounds H3-99.

[0085] Preparation Example 1

[0086] Synthesis of compound H1-5:

[0087]

[0088] Procedure: Under an 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 becomes clear. Then 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), and sodium tert-butoxide (3.8 g, 0.04 mmol). Heat the reaction mixture to 120 °C and continue the reaction for 10 h. After the reaction is completed, filter while hot using diatomaceous earth. Cool the filtrate to room temperature, add purified water for washing, separate the layers, and retain the organic phase. Then extract the aqueous phase with ethyl acetate. Combine the organic phases, dry over anhydrous magnesium sulfate, concentrate, and column chromatograph (dichloromethane / petroleum ether) to obtain compound H1-5, weighing 4.7 g, with a yield of 76%, an HPLC content of 99%, and LC-MS showing a molecular weight of 620.2. The NMR spectrum of compound H1-5 is as shown in Figure 2 shown.

[0089] 1H NMR 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).

[0090] Preparation Example 2

[0091] Synthesis of compound H1-19:

[0092]

[0093] Procedure: Referring to the synthesis process of compound H1-5, replace 1-chloro-4-phenylnaphthalene with 4-bromophenanthrene (2.7 g, 0.0105 mol) to obtain compound H1-19, weighing 4.4 g, with a yield of 74%, an HPLC content of 99%, and LC-MS showing a molecular weight of 594.3. The NMR spectrum of compound H1-19 is as shown in Figure 3 shown.

[0094] 1H NMR 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).

[0095] Preparation Example 3

[0096] Synthesis of Compound H2-25:

[0097]

[0098] Procedure: Referring to the synthesis procedure of Compound H1-5, replace 1-chloro-4-phenylnaphthalene with 2-bromo-9,9′-spirobixanthene (4.5 g, 0.0105 mol) to obtain Compound H2-25, weighing 5.6 g, with a yield of 73% and an HPLC content of 99%. LC-MS shows a molecular weight of 764.3. The NMR spectrum of Compound H2-25 is as Figure 4 shown.

[0099] 1H NMR 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).

[0100] Preparation Example 4

[0101] Synthesis of Compound H2-43:

[0102]

[0103] Operation procedure: Referring to the synthesis process of compound H1-5, replace 1-chloro-4-phenylnaphthalene 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%, an HPLC content of 99%, and LC-MS showing a molecular weight of 634.3. The NMR spectrum of compound H2-43 is as follows Figure 5 shown

[0104] 1H NMR 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).

[0105] Preparation Example 5

[0106] Synthesis of compound H3-2:

[0107]

[0108] Operation procedure: Referring to the synthesis process of compound H1-5, replace 1-chloro-4-phenylnaphthalene 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%, an HPLC content of 99%, and LC-MS showing a molecular weight of 699.3. The NMR spectrum of compound H3-2 is as follows Figure 6 shown

[0109] 1H NMR 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).

[0110] Preparation Example 6

[0111] Synthesis of Compound H3-37:

[0112]

[0113] Procedure: Referring to the synthesis process of Compound H1-5, replace 1-chloro-4-phenylnaphthalene with 2-cyano-4-bromopyrimidine (1.9 g, 0.0105 mol) to obtain Compound H3-37, with a weight of 3.7 g, a yield of 71%, an HPLC content of 99%, and LC-MS showing a molecular weight of 521.2. The NMR spectrum of Compound H3-37 is as Figure 7 shown.

[0114] 1H NMR 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).

[0115] Next, according to the structural information of the light-emitting layer of the electroluminescent device given in Table 1, electroluminescent devices of Examples 1 to 44 and Comparative Examples 1 to 5 were prepared.

[0116] Schematic structural diagrams of the electroluminescent devices in the examples and comparative examples of the present invention are as Figure 1 shown, including 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 protection layer 11.

[0117] Electroluminescent device of Example 1 containing Compound H1-7

[0118] The electroluminescent device of this example containing Compound H1-7 includes, in the direction from the anode to the cathode, polyethylene terephthalate (PET) plastic, indium tin oxide (ITO) conductive glass, MoO3, HT-2, EB-2, a light-emitting layer, HB-1, ET-2, LiF, Al-Mg (Al:Mg = 9:1), and CPL in sequence; the material used for CPL is ;

[0119] Among them, the light-emitting layer is composed of H1-7 and Ir(ppy)3 with a mass ratio of 99:1.

[0120] The preparation method of the above-mentioned electroluminescent device containing compound H1-7 includes the following steps:

[0121] 1. Using 1.5-mm PET plastic as substrate 1 and 0.15-mm ITO conductive glass as anode 2, wash them successively by alkali washing, pure water washing, drying, and ultraviolet-ozone washing to remove the organic residues on the surfaces of the PET plastic and the ITO conductive glass.

[0122] 2. Adhere a layer of ITO conductive glass on the PET plastic. Using a vacuum evaporation device, evaporate 20 nm thick MoO3 as hole injection layer 3, then evaporate 110 nm thick HT-2 as hole transport layer 4, subsequently evaporate 30 nm thick EB-2 as electron blocking layer 5, continue to evaporate a 60-nm thick light-emitting layer 6 formed by compound H1-7 (host luminescent material) and Ir(ppy)3 (guest luminescent material) with a mass ratio of 99:1 on EB-2, then continue to evaporate 10 nm thick HB-1 as hole blocking layer 7 on the light-emitting layer 6, then continue to evaporate 30 nm thick ET-2 as electron transport layer 8, then continue to evaporate 16 nm of LiF as electron injection layer 9 on the electron transport layer 8. After the evaporation of the electron injection layer 9 is completed, sputter a 10-nm thick Al-Mg (Al:Mg = 9:1) alloy as cathode 10 by low-temperature sputtering, and finally continue to evaporate 40 nm thick CPL as the covering protection layer 11 on the cathode 10.

[0123] 3. Vacuum package MoO3, HT-2, EB-2, light-emitting layer 6, HB-1, ET-2, and LiF to obtain the electroluminescent device.

[0124] Examples 2 to 18

[0125] The difference from Example 1 is that in Examples 2 to 18, 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 are used as the host luminescent materials of the light-emitting layer 6 respectively.

[0126] Examples 19 to 40

[0127] The difference from Example 1 is that in Examples 19 to 40, BH-1 is used as the host luminescent material of the light-emitting layer 6, and in Examples 19 to 40, 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 are used as the guest luminescent materials of the light-emitting layer 6 respectively.

[0128] Examples 41 to 44

[0129] The difference from Example 1 is that in the light-emitting layer 6 of Examples 41 to 44, compounds H2-21, H2-25, H2-33, and H2-36 are used as the first host luminescent materials respectively, compound H3-90 is used as the second host luminescent material, and the mass ratio of the first host luminescent material, the second host luminescent material, and the guest luminescent 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 in sequence.

[0130] Comparative Example 1

[0131] The difference from Example 1 is that in the light-emitting layer 6, HB-1 is used as the host luminescent material.

[0132] The structure of the electroluminescent device of Comparative Example 1 is: PET substrate / ITO / MoO3 (20 nm) / HT-2 (110 nm) / EB-2 (30 nm) / BH-1:Ir(ppy)3 = 99:1 (60 nm) / HB-1 (10 nm) / ET-2 (30 nm) / LiF (16 nm) / Al:Mg = 9:1 (10 nm) / CPL (40 nm).

[0133] Comparative Example 2

[0134] The difference from Example 1 is that in the light-emitting layer 6, BH-2 is used as the host luminescent material.

[0135] The structure of the electroluminescent device of Comparative Example 2 is: PET substrate / ITO / MoO3 (20 nm) / HT-2 (110 nm) / EB-2 (30 nm) / BH-2:Ir(ppy)3 = 99:1 (60 nm) / HB-1 (10 nm) / ET-2 (30 nm) / LiF (16 nm) / Al:Mg = 9:1 (10 nm) / CPL (40 nm).

[0136] Comparative Example 3

[0137] 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.

[0138] The structure of the electroluminescent device of Comparative Example 3 is: PET substrate / ITO / MoO3 (20 nm) / HT-2 (110 nm) / EB-2 (30 nm) / BH-1:C545T = 99:1 (60 nm) / HB-1 (10 nm) / ET-2 (30 nm) / LiF (16 nm) / Al:Mg = 9:1 (10 nm) / CPL (40 nm).

[0139] Comparative Example 4

[0140] The difference from Example 1 is that in the light-emitting layer 6, BH-1 is used as the host light-emitting material and Compound 41 in Chinese Patent CN106187861B is used as the guest light-emitting material.

[0141] The structure of the electroluminescent device of Comparative Example 4 is: PET substrate / ITO / MoO3 (20 nm) / HT-2 (110 nm) / EB-2 (30 nm) / BH-1:Compound 41 = 99:1 (60 nm) / HB-1 (10 nm) / ET-2 (30 nm) / LiF (16 nm) / Al:Mg = 9:1 (10 nm) / CPL (40 nm).

[0142] Comparative Example 5

[0143] 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.

[0144] The structure of the electroluminescent device of Comparative Example 5 is: PET substrate / ITO / MoO3 (20 nm) / HT-2 (110 nm) / EB-2 (30 nm) / RH1-3:RH2-2:Ir(ppy)3 = 40:60:1 (60 nm) / HB-1 (10 nm) / ET-2 (30 nm) / LiF (16 nm) / Al:Mg = 9:1 (10 nm) / CPL (40 nm).

[0145] The electroluminescent devices in the above examples and comparative examples were fabricated into samples of 30 mm × 30 mm, and the anode and cathode were connected with a commonly known driving circuit in the industry to test each light-emitting performance index. The test results are shown in Table 2.

[0146] As can be seen from the test results in Table 2, compared with Comparative Examples 1 to 4, the electroluminescent devices prepared from the preferred 9,9-bifluorene-fused indole derivatives of the present invention in Examples 1 to 44 have obvious advantages in the comprehensive luminous efficiency. As can be seen from Examples 1 to 18, for the electroluminescent devices prepared with the preferred compound of the present invention as the host luminescent material, compared with Comparative Example 1, the current efficiency is increased by about 50%, and the service life LT95 is extended by about 40%. As can be seen from Examples 19 to 40, for the electroluminescent devices prepared with the preferred compound of the present invention as the guest luminescent material, compared with Comparative Example 3, the current efficiency is increased by about 45%, and the service life LT95 is extended by about 80%; compared with Comparative Example 4, the current efficiency is increased by about 80%, and the service life LT95 is extended by about 100%. As can be seen from Examples 41 to 44, for the electroluminescent devices prepared with the preferred compound of the present invention as both the dual-host luminescent material and the hole transport layer material, compared with Comparative Example 5, the turn-on voltage is significantly reduced, and the service life LT95 is extended nearly 2-fold.

[0147] The above content is only to illustrate the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the present invention.

Claims

1. A 9,9-bifluorenylindole derivative, characterized in that, The structural formula of the 9,9-bifluorene-fused indole derivatives is shown in Formula (1): Formula (1) Wherein, L is selected from one of the following groups L1-1 to L1-19, L2-1 to L2-32, L3-1 to L3-89: Among the groups L1-1 to L1-19, L2-1 to L2-32, and L3-1 to L3-89, " " represents the position where L is bonded to the main structure. Among them, the groups L1-9, L1-10, L1-12, L1-13, L1-14, L1-16, L1-17, L1-18, L1-19, L2-4, L2-7, L2-8, L2-9, L2-10, L2-18, L2-19, L2-21, L2-24, L2-27, L2-28, L3-4, L3-5, L3-19, L3-45, L3-78, L3-79, L3-87, and L3-88 are each bonded to the main structure only through one " "; The main structure is .

2. An electroluminescent device, characterized in that, It includes a cathode, an anode, and an organic layer located between the cathode and the anode. The organic layer includes a hole transport layer, a light-emitting layer, and an electron transport layer. 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 the 9,9-bifluorene-fused indole derivatives described in Claim 1.

3. The electroluminescent device according to claim 2, characterized in that, The components of the hole transport layer include the 9,9-bifluorene-fused indole derivatives described in Claim 1.

4. The electroluminescent device according to claim 2, wherein, 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-bifluorene-fused indole derivatives described in Claim 1.

5. The electroluminescent device according to claim 2, 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-bifluorene-fused indole derivatives described in Claim 1.

6. An electroluminescent device, characterized in that, It includes a cathode, an anode, and an organic layer located between the cathode and the anode. The organic layer includes a hole transport layer, a light-emitting layer, and an electron transport layer. 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; the first host light-emitting material includes the 9,9-bifluorene-fused indole derivatives described in Claim 1, wherein L is selected from one of the groups L2-1 to L2-32; the second host light-emitting material includes the 9,9-bifluorene-fused indole derivatives described in Claim 1, wherein L is selected from one of the groups L3-1 to L3-89.

7. An electroluminescent device, characterized in that, It includes a cathode, an anode, and an organic layer located between the cathode and the anode. The organic layer includes a hole transport layer, a light-emitting layer, and an electron transport layer. 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 guest light-emitting material includes the 9,9-bifluorene-fused indole derivatives described in Claim 1, wherein L is selected from one of the groups L3-1 to L3-89.

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