A hole transport material based on fluorene and triphenylethylene and its preparation method and application

Abstract

A hole transport material based on fluorene and triphenylethylene, which is selected from at least one of the compounds represented by formula (1): #imgabs0# In formula (1), Ar1 and Ar2 are each independently selected from a C6-C30 substituted aryl group or a C6-C30 unsubstituted aryl group, and repeated Ar1 or Ar2 are the same or different; R1 and R2 are each independently selected from hydrogen, a C1-C10 alkyl group, a C6-C10 substituted aryl group or a C6-C10 unsubstituted aryl group, and repeated R1 or R2 are the same or different; R is selected from an aniline group, a diphenylamine group, or the structure represented by formula (2) or formula (3): #imgabs1# The hole transport material can be used in organic electroluminescent devices, can reduce the operating voltage, and improve the device efficiency, and is a hole transport material with excellent performance.

Description

Technical Field

[0001] The present invention relates to the technical field of organic electroluminescent devices, and in particular to a hole transport material based on fluorene and triphenylethylene, and a preparation method and application thereof. Background Art

[0002] Organic light-emitting diodes (OLEDs) are considered a revolutionary new generation display technology due to their numerous advantages, including self-luminescence, thinness, light weight, low energy consumption, fast response time, full-color display, and flexibility. They are also used in lighting applications and as backlight sources for liquid crystal displays. OLEDs typically have a multilayer structure, fabricated by depositing multiple layers of organic optoelectronic materials between two metal electrodes via spin coating or vacuum evaporation. Classified by material function, OLED devices include a hole injection layer, an electron blocking layer, a hole transport layer, a light-emitting layer, an electron transport layer, a hole blocking layer, and an electron injection layer. The luminescence principle of OLEDs is that, driven by an external electric field, electrons generated at the cathode and holes generated at the anode are transported through the electron injection layer / hole injection layer and electron transport layer / hole transport layer, respectively. The carriers recombine in the light-emitting layer to produce excitons, which transfer energy to the luminescent material in the light-emitting layer, generating fluorescence or phosphorescence. OLEDs can achieve different emission colors by varying the materials in the light-emitting layer, and the device's luminescence characteristics and performance can be altered by adjusting and varying the material combination of each layer.

[0003] Hole transport materials are very important for OLEDs. The efficiency of OLED devices is largely determined by the performance of carrier transport materials. In addition, since the mobility of holes is significantly higher than that of electrons, the thickness of the hole transport layer is very large, resulting in the largest proportion of hole transport materials among all organic materials. Hole transport materials usually contain sp 3 Hybridized nitrogen atoms have strong redox properties, and the Joule heat generated during device operation will inevitably affect them, causing degradation of their molecular structure or damage to the thin film structure, resulting in a decrease in both device stability and efficiency. Therefore, the thermal stability of hole transport materials is very important. In addition, the hole mobility and energy level of the hole transport material are also important. The energy level matching that of the adjacent functional layer and the hole mobility matching that of the electron transport material facilitate the recombination of holes and electrons in the light-emitting layer, thereby improving the efficiency and life of the device. Summary of the Invention

[0004] In order to overcome the problems existing in the prior art, the present invention provides a hole transport material based on fluorene and triphenylethylene and a preparation method thereof. This material has good thermal stability and a high HOMO energy level, and the organic electroluminescent device prepared using this material has higher efficiency, lower operating voltage and longer service life.

[0005] One of the objects of the present invention is to provide a hole transport material based on fluorene and triphenylethylene, which is selected from at least one of the compounds represented by formula (1):

[0006]

[0007] In formula (1), Ar1 and Ar2 are each independently selected from a C6-C30 substituted aryl group or a C6-C30 unsubstituted aryl group, and repeated Ar1 or Ar2 are the same or different; R1 and R2 are each independently selected from hydrogen, a C1-C10 alkyl group, a C6-C10 substituted aryl group or a C6-C10 unsubstituted aryl group, and repeated R1 or R2 are the same or different; R is selected from an aniline group, a diphenylamine group (-Ph-NH-Ph-), or the structure represented by formula (2) or formula (3):

[0008]

[0009] The hole transport material described in this invention has a high glass transition temperature and can be produced by spin coating. Spin coating is suitable for producing large and extra-large OLED panels, while evaporation is suitable for small and medium-sized panels. Compared to evaporation, spin coating offers the advantages of low equipment cost, simplified maintenance, low process cost, and simple operation.

[0010] In a preferred embodiment, in formula (1), Ar1 and Ar2 are each independently selected from phenyl, naphthyl, biphenyl, phenanthrenyl, dibenzofuranyl, dibenzothiophenyl or 9,9-dimethylfluorenyl, and repeated Ar1 or Ar2 are the same or different; R1 and R2 are each independently selected from hydrogen, C1-C5 alkyl, C1-C5 substituted alkyl or C6-C10 aryl, and repeated R1 or R2 are the same or different; R is selected from the structure shown in formula (2) or formula (3).

[0011] In a further preferred embodiment, in formula (1), Ar1 and Ar2 are each independently selected from phenyl, R1 and R2 are each independently selected from hydrogen, methyl, ethyl, tert-butyl, phenyl, tolyl, naphthyl or phenanthrenyl, and repeated R1 or R2 are the same or different; R is selected from the structure shown in formula (2) or formula (3).

[0012] In the present invention, repeated Ar1 or Ar2 being the same or different means that the corresponding Ar1 on the left and right sides of formula (1) are the same or different, and the corresponding Ar2 on the left and right sides of formula (1) are the same or different; repeated R1 or R2 being the same or different means that the corresponding R1 on the left and right sides of formula (1) are the same or different, and the corresponding R2 on the left and right sides of formula (1) are the same or different.

[0013] In a preferred embodiment, the compound represented by formula (1) is represented by formula (4) or formula (5):

[0014]

[0015]

[0016] Wherein, R1 and R2 have the same definitions as in formula (1).

[0017] In a preferred embodiment, the hole transport material is selected from at least one of the compounds represented by the following formulae (a) to (h):

[0018]

[0019]

[0020]

[0021] A second object of the present invention is to provide a method for preparing the hole transport material of the first object of the present invention, comprising: reacting substances including the compound represented by formula (6), biboronic acid pinacol ester, and the compound represented by formula (7) as raw materials to obtain the hole transport material;

[0022]

[0023] in:

[0024] In formula (6), X1 is selected from halogen; Ar1 ​​and Ar2 are each independently selected from a C6-C30 substituted aryl group or a C6-C30 unsubstituted aryl group; R1 and R2 are each independently selected from hydrogen, a C1-C10 alkyl group, a C6-C10 substituted alkyl group or a C6-C10 unsubstituted aryl group;

[0025] In formula (7), X1 is selected from halogen, and R is selected from aniline, diphenylamine (-Ph-NH-Ph-), the structure represented by formula (2) or formula (3):

[0026]

[0027] In a preferred embodiment, in formula (6), X1 is selected from chlorine, bromine or iodine, Ar1 and Ar2 are each independently selected from phenyl, naphthyl, biphenyl, phenanthrenyl, dibenzofuranyl, dibenzothiophenyl or 9,9-dimethylfluorenyl; R1 and R2 are each independently selected from hydrogen, C1-C5 alkyl, C1-C5 substituted alkyl or C6-C10 aryl; and / or, in formula (7), X2 is selected from chlorine, bromine or iodine, and R is selected from the structure shown in formula (2) or formula (3).

[0028] In a further preferred embodiment, in formula (6), X1 is selected from bromine or iodine, Ar1 and Ar2 are each independently selected from phenyl; R1 and R2 are each independently selected from hydrogen, methyl, ethyl, isopropyl, isobutyl or phenyl (preferably methyl or hydrogen); and / or, in formula (7), X2 is selected from bromine or iodine, and R is selected from the structure shown in formula (2) or formula (3).

[0029] In a preferred embodiment, the preparation method comprises the following steps:

[0030] Step 1: mixing the compound represented by formula (6), biboronic acid pinacol ester and base I, adding solvent I and catalyst I, heating to react, and post-treating to obtain an intermediate product;

[0031] Step 2: Mix the intermediate product, the compound represented by formula (7) and base II, add solvent II and catalyst II, heat to react, and obtain the hole transport material through post-treatment.

[0032] In a preferred embodiment, the molar ratio of the compound represented by formula (6) to the diboric acid pinacol ester is 1:(1-1.5), preferably 1:(1.1-1.3), for example 1:1.2.

[0033] For example, the molar ratio of the compound represented by formula (6) to the diboric acid pinacol ester is 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4 or 1:1.5.

[0034] In a preferred embodiment, the molar ratio of the compound represented by formula (7) to the intermediate product is 1:(2.0-2.2), preferably 1:(2.05-2.1).

[0035] For example, the molar ratio of the compound represented by formula (7) to the compound represented by formula (6) is 1:2, 1:2.05, 1:2.08, 1:2.1, 1:2.15, 1:2.18 or 1:2.2.

[0036] In a preferred embodiment, in step 1, the base I is selected from at least one of potassium acetate, sodium acetate, zinc acetate, and magnesium acetate.

[0037] In a further preferred embodiment, in step 1, the molar ratio of the compound represented by formula (6) to the base I is 1:(2-4), preferably 1:(2-3).

[0038] For example, in step 1, the molar ratio of the compound represented by formula (6) to the base I is 1:2, 1:3 or 1:4.

[0039] In a preferred embodiment, in step 1, the catalyst I is selected from a palladium-based catalyst.

[0040] In a further preferred embodiment, the palladium-based catalyst is selected from at least one of tris(dibenzylideneacetone)dipalladium Pd2(dba)3, palladium acetate Pd(OAc)2, 1,1'-bis(diphenylphosphinoferrocene)palladium dichloride PdCl2(dppf), and Pd / C.

[0041] In a further preferred embodiment, in step 1, the weight ratio of the catalyst I to the compound represented by formula (6) is (0.005-0.03):1, preferably (0.005-0.015):1.

[0042] For example, in step 1, the weight ratio of the catalyst I to the compound represented by formula (6) is 0.005:1, 0.01:1, 0.02:1 or 0.03:1.

[0043] In a preferred embodiment, in step 1, the solvent I is selected from an organic solvent, preferably at least one selected from toluene, o-xylene, m-xylene, and p-xylene, such as toluene.

[0044] In a further preferred embodiment, based on 1 g of the compound represented by formula (6), the amount of the solvent used is 5 to 20 mL, preferably 8 to 12 mL.

[0045] For example, based on 1 g of the compound represented by formula (6), the amount of the solvent used is 5 mL, 8 mL, 10 mL, 12 mL, 15 mL, 18 mL or 20 mL.

[0046] In a preferred embodiment, in step 1, the reaction is carried out by heating to reflux.

[0047] In a further preferred embodiment, in step 1, the reaction is carried out for 1 to 10 hours, more preferably 3 to 8 hours.

[0048] In a preferred embodiment, step 1 is carried out under a protective atmosphere, preferably under nitrogen.

[0049] In a preferred embodiment, in step 1, the post-treatment includes: passing through a silica gel column, washing and crystallization.

[0050] In a further preferred embodiment, the washing is performed using the solvent I described in step 1.

[0051] In a further preferred embodiment, the crystallization is carried out using an alcohol solvent, preferably ethanol.

[0052] Preferably, after the solid is precipitated, it is filtered and washed with an alcohol solvent.

[0053] In a preferred embodiment, in step 2, the catalyst II is selected from palladium-based catalysts.

[0054] In a further preferred embodiment, the palladium-based catalyst is selected from at least one of tris(dibenzylideneacetone)dipalladium Pd2(dba)3, palladium acetate Pd(OAc)2, 1,1'-bis(diphenylphosphinoferrocene)palladium dichloride PdCl2(dppf), and Pd(PPh3)4.

[0055] In a further preferred embodiment, in step 2, the weight ratio of the catalyst II to the intermediate product is (0.005-0.04):1, preferably (0.008-0.03):1.

[0056] Wherein, in step 2, the weight ratio of the catalyst II to the intermediate product is 0.005:1, 0.008:1, 0.01:1, 0.02:1, 0.03:1 or 0.04:1

[0057] In a preferred embodiment, in step 2, the base II is selected from at least one of potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate.

[0058] In a further preferred embodiment, in step 2, the molar ratio of the base II to the intermediate is 1:(0.1-3), preferably 1:(0.3-2).

[0059] Wherein, in step 2, the molar ratio of the base II to the compound represented by formula (7) is 1:0.1, 1:0.3, 1:0.5, 1:0.8, 1:1, 1:1.5, 1:2, 1:2.5 or 1:3.

[0060] In a preferred embodiment, in step 2, the reaction is carried out by heating to reflux.

[0061] In a further preferred embodiment, in step 2, the reaction is carried out for 1 to 10 hours, more preferably 3 to 8 hours.

[0062] In a preferred embodiment, in step 2, the solvent II is selected from an organic solvent and / or water, preferably at least one selected from aromatic solvents, alcohol solvents, and water, and more preferably at least one selected from toluene, ethanol, and water.

[0063] In a preferred embodiment, step 2 is carried out under a protective atmosphere, preferably under nitrogen.

[0064] In a preferred embodiment, in step 2, the post-treatment includes: cooling and crystallizing, dissolving the crystals and passing them through a silica gel column, washing, and crystallizing again.

[0065] In a further preferred embodiment:

[0066] Cooling and crystallizing the product, followed by filtering, and then washing the crystals with water and an alcohol solvent in sequence; and / or,

[0067] Among them, water washing is to wash away inorganic salts, and alcohol washing is to wash away most of the water.

[0068] The dissolving of the crystals is performed as follows: dissolving the crystals under reflux using at least one of chlorobenzene, xylene, dichlorobenzene, trimethylbenzene, and toluene (preferably chlorobenzene); and / or,

[0069] The washing is performed using a solvent that dissolves the crystals, and the crystallization is repeated and then filtered and washed with an alcohol solvent.

[0070] In a preferred embodiment, the compound represented by formula (6) can be directly purchased through existing technology or prepared through methods disclosed in the existing technology.

[0071] Preferably, the compound represented by formula (6) is obtained as follows:

[0072] (a) The compound represented by formula (6-1) reacts with the compound represented by formula (6-2) to obtain the compound represented by formula (6-3); X1

[0073] (b) halogenating the compound represented by formula (6-3) to obtain a compound represented by formula (6-4);

[0074] (c) The compound represented by formula (6-4) reacts with the compound represented by formula (6-5) to obtain the compound represented by formula (6).

[0075]

[0076] In formulas (6-1) to (6-5), Ar1, Ar2, R1, and R2 have the same definitions as Ar1, Ar2, R1, and R2 in formula (6), and in formula (6-5), R3 and R4 are each independently selected from an alkyl group, preferably an alkyl group from C1 to C10 (for example, a methyl group, an ethyl group, an isopropyl group, or an isobutyl group).

[0077] In a preferred embodiment, step (a) performs a Suzuki coupling reaction, and the specific reaction conditions are not specifically limited herein. As long as the conditions disclosed in the prior art can achieve a Suzuki coupling reaction, they are the reaction conditions of step (a) of the present invention.

[0078] In a further preferred embodiment, the compound of formula (6-1), the compound represented by formula (6-2), an alkaline substance (such as potassium carbonate) and a solvent are mixed, and a palladium-based catalyst (such as Pd(PPh3)4) is added under a protective atmosphere. The mixture is reacted under reflux for 2 to 8 hours. After the reaction is completed, the mixture is cooled, separated and the organic phase is taken. The organic phase is concentrated, filtered, washed and crystallized in sequence to obtain the compound represented by formula (6-3).

[0079] In a preferred embodiment, in step (b), the halogenation treatment is chlorination treatment and / or bromination treatment, preferably bromination treatment.

[0080] The chlorination and bromination treatments may be those disclosed in the prior art. Preferably, liquid bromine is used for bromination.

[0081] In a further preferred embodiment, the compound represented by formula (6-3) is mixed with a solvent, and a mixture of liquid bromine and the solvent is added dropwise thereto (preferably at -10 to 10°C), and the reaction is carried out for 0.5 to 6 hours. After the reaction is completed, a saturated salt solution is used for extraction and separation, and the organic phase is washed with water and then crystallized to obtain the compound represented by formula (6-4).

[0082] In a preferred embodiment, step (c) performs a Wittig reaction, and the specific reaction conditions are not specifically limited herein. As long as the conditions disclosed in the prior art can achieve a Wittig reaction, they are the reaction conditions of step (c) of the present invention.

[0083] In a further preferred embodiment, the compound represented by formula (6-4), the compound represented by formula (6-5), an alkali metal alcohol salt and a solvent are mixed and refluxed for 0.5 to 6 hours. After the reaction is completed, the mixture is cooled, acid is added to quench the reaction, and the mixture is concentrated. The aqueous phase is extracted with ethyl acetate, and then the mixture is separated, concentrated and filtered in sequence to obtain the compound represented by formula (6).

[0084] The third object of the present invention is to provide an application of the hole transport material described in one of the objects of the present invention in an organic electroluminescent device, preferably in a hole transport layer, a hole injection layer or an electron blocking layer of the organic electroluminescent device, preferably in a hole transport layer.

[0085] A fourth object of the present invention is to provide an organic electroluminescent device, comprising an anode, a cathode and an organic layer, wherein the organic layer comprises at least one of a light-emitting layer, a hole injection layer, a hole transport layer, a hole blocking layer, an electron injection layer and an electron transport layer, wherein at least one of the organic layers is made of raw materials including the hole transport material described in one of the objects of the present invention or the hole transport material obtained by the preparation method described in the second object of the present invention.

[0086] In a preferred embodiment, the organic layer includes a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer and an electron injection layer in sequence.

[0087] In a further preferred embodiment, the hole injection layer and / or hole transport layer in the organic layer is made of raw materials including the hole transport material described in one of the objectives of the present invention or the hole transport material obtained by the preparation method described in the second objective of the present invention.

[0088] In a further preferred embodiment, the hole injection layer is adjacent to the anode, and the electron injection layer is adjacent to the cathode.

[0089] When the organic electroluminescent device of the present invention selects the hole transport material of the present invention as the hole transport layer, it has excellent photoelectric properties, greatly reduces the energy barrier with the hole injection layer, and is suitable as the hole transport layer of the organic electronic light-emitting device, so that the device has higher current efficiency and device efficiency.

[0090] In summary, the organic electroluminescent device of the present invention has the advantages of low starting voltage, high luminous efficiency, good stability, and long life.

[0091] Compared with the prior art, the present invention has the following beneficial effects:

[0092] (1) The hole transport material based on fluorene and triphenylethylene of the present invention has a novel structure and excellent photoelectric properties. Its HOMO energy level is about -5.4 eV, which greatly reduces the energy barrier with the hole injection layer. It is suitable as a hole transport layer of organic electronic light-emitting devices and has higher power efficiency and device efficiency.

[0093] (2) The compounds of the present invention have very good thermal stability, with their glass transition temperatures being greater than 175°C and their thermal decomposition temperatures being higher than 500°C.

[0094] (3) The compounds of the present invention can be used in devices using a spin coating process and have excellent performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] Figure 1 A schematic structural diagram of an organic electroluminescent device according to the present invention is shown;

[0096] Among them, 110 represents a glass substrate, 120 represents an anode, 130 represents a hole injection layer, 140 represents a hole transport layer, 150 represents a light-emitting layer, 160 represents an electron transport layer, 170 represents an electron injection layer, and 180 represents a cathode.

[0097] Figure 2 The TGA curves of compound 1 and compound 2 are shown, and their thermal decomposition temperatures (Td , the temperature when weight loss is 5% is 504 and 540℃ respectively. d It is 340°C. It can be seen that the thermal decomposition temperature of the material of the present invention is significantly higher than that of NPD.

[0098] Figure 3 The DSC curves of compound 1 and compound 2 are shown, and their glass transition temperatures (T g ) are 178 and 200℃ respectively.

[0099] Figure 4 The absorption and fluorescence spectra of Compound 1 and Compound 2 are shown, and their absorption and fluorescence are at 350 and 445 nm, and 348 and 431 nm, respectively.

[0100] Figure 5 The cyclic voltammograms of compound 1 and compound 2 are shown, and their oxidation potentials are 1.02 and 0.97 V, respectively, and their HOMO energy levels are -5.42 and -5.37 eV, respectively.

[0101] Figure 6 The CE-L-EQE curve of the device made with compound 1 as the hole transport material is shown. DETAILED DESCRIPTION

[0102] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art to the present invention based on the contents of the present invention still fall within the scope of protection of the present invention.

[0103] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0104] In the embodiment of the present invention, intermediate a, intermediate b and raw material 1 are prepared as follows (see below for the reaction process):

[0105]

[0106] (1) Synthesis of Raw Material 1

[0107] Synthesis of intermediate a:

[0108] 2-Bromo-9,9-dimethylfluorene (40 g, 146.4 mmol), p-formylphenylboronic acid (24.2 g, 161.4 mmol) and potassium carbonate (40.5 g, 293.0 mmol) were added to a flask, followed by toluene (240 mL), ethanol (120 mL) and deionized water (120 mL). Under nitrogen protection, Pd(PPh3)4 (0.6 g) was added, and the mixture was refluxed for 5 hours. The mixture was cooled, separated, and the organic phase was concentrated to remove water and ethanol. After adding toluene (200 mL), the mixture was filtered through silica gel and washed with toluene. The filtrate was concentrated to about 80 mL, and ethanol (80 mL) was added dropwise for crystallization. The mixture was filtered, washed with ethanol, and dried to obtain 39 g of a white solid with a yield of 89%. 1 H NMR (400MHz, CDCl3) δ: 10.07 (s, 1H), 7.95-7.99 (m, 2H), 7.75-7.84 (m, 4H), 7.69 (d, J = 1.6 Hz,1H),7.62(dd,J=1.6Hz,7.6Hz,1H),7.45-7.48(m,1H),7.33-7.39(m,2H),1.55(s,6H).

[0109] Synthesis of intermediate b: Intermediate a (38 g, 127.4 mmol) and dichloromethane (320 mL) were added to a flask, and liquid bromine (21.9 g, 137.2 mmol) and dichloromethane (80 mL) were placed in a dropping funnel, and liquid bromine solution was added dropwise at 0-5°C. After reacting for 3 h, thin layer chromatography showed that the reaction was complete. Saturated sodium sulfite solution was added to quench the reaction, the liquid was separated, the organic phase was washed with water once, concentrated to about 80 mL, and ethanol (60 mL) was added dropwise for crystallization. The mixture was filtered, washed with ethanol, and dried to obtain 36 g of a white solid with a yield of 75%. 1 H NMR (400MHz, CDCl3) δ: 10.08 (s, 1H), 7.95-8.00 (m, 2H), 7.76-7.84 (m, 3H), 7.58-7.68 (m, 4H), 7.48-7.51 (m, 1H), 1.55 (s, 6H).

[0110] Synthesis of raw material 1: Diphenylmethane bromide (20 g, 80.9 mmol) and triethyl phosphite (100 mL) were added to a flask, refluxed for 3 h, and the excess triethyl phosphite was distilled off under reduced pressure. Tetrahydrofuran (200 mL), sodium tert-butoxide (9.3 g, 96.8 mmol) and intermediate b (25.5 g, 67.6 mmol) were added, refluxed for 3 h, cooled, and quenched with dilute hydrochloric acid solution. Most of the THF was concentrated, and the aqueous phase was extracted with ethyl acetate (500 mL). The organic phase was separated and concentrated to about 50 mL. The precipitated solid was filtered, washed with ethanol, and dried to obtain 12 g of a light yellow solid with a yield of 33%. 1H NMR (400MHz, CDCl3) δ: 7.70 (d, J = 8.0 Hz, 1H), 7.52-7.58 (m, 4H), 7.45 (t, J = 7. 2Hz, 3H), 7.27-7.38 (m, 10H), 7.11 (d, J = 8.0Hz, 2H), 7.02 (s, 1H), 1.50 (s, 6H).

[0111] (2) Synthesis of Raw Material 2

[0112] The synthesis process of raw material 1 in the above (1) was repeated, except that an equal molar amount of 2-bromo-9,9-diethylfluorene was used to replace 2-bromo-9,9-dimethylfluorene.

[0113] (3) Synthesis of Raw Material 3

[0114] The synthesis process of raw material 1 in the above (1) was repeated, except that an equal molar amount of 2-bromo-9,9-diphenylfluorene was used to replace 2-bromo-9,9-dimethylfluorene.

[0115] Example 1 Synthesis of Compound 1

[0116]

[0117] Synthesis of intermediate 1

[0118] Raw material 1 (2.0 g, 3.80 mmol), pinacol diboronate (1.16 g, 4.56 mmol) and potassium acetate (1.12 g, 11.42 mmol) were added to a flask, and anhydrous toluene (20 mL) and Pd(PPh3)2Cl2 (20 mg) were added. The mixture was refluxed under nitrogen for 5 h. TLC showed that the reaction was complete. Heating was stopped, and the mixture was passed through a small amount of silica gel while hot, rinsed with toluene, and concentrated to near dryness. 2 mL of ethanol was added and stirred to precipitate a solid, which was filtered and rinsed with ethanol to obtain 1.98 g of a light yellow solid with a yield of 90.8%. 1 H NMR (400MHz, CDCl3, δ):7.72-7.76(m,2H),7.56-7.59(m,2H),7.48–7.53(m,3H),7.48(d,J =1.6Hz,1H),7.43–7.47(m,5H),7.35–7.4(m,7H),7.06(s,1H),1.56(s,6H),1.24(s,12H).

[0119] Synthesis of compound 1

[0120] Intermediate product 1 (0.3 g, 0.52 mmol), 4,4'-dibromotriphenylamine (0.1 g, 0.25 mmol), and potassium carbonate (0.1 g, 0.72 mmol) were added to a flask. Toluene (1 mL), ethanol (0.5 mL), deionized water (0.5 mL), and Pd(PPh3)2Cl2 (5 mg) were then added. The mixture was refluxed under nitrogen for 5 h. TLC indicated the reaction was complete. The mixture was cooled, the precipitated solid was filtered, and then washed with deionized water and ethanol. The filter cake was dissolved in 5 mL of chlorobenzene under reflux. While still hot, it was passed through a small amount of silica gel, rinsed with chlorobenzene, and concentrated to near dryness. The precipitated solid was filtered and rinsed with ethanol to obtain 0.18 g of a light yellow solid, with a yield of 64.3%. MALDI-TOF (m / z): M calcdfor: C 88 H 67 N,1137.5274,found,1137.5258.Elemental Analysis:C,92.84;H,5.93;N,1.23;found,C,92.74;H,5.97;N,1.29.

[0121] Example 2 Synthesis of Compound 2

[0122]

[0123] The preparation of intermediate 1 is described in Example 1.

[0124] Synthesis of compound 2

[0125] Intermediate 1 (0.3 g, 0.52 mmol), 3,6-dibromo-9-phenylcarbazole (0.1 g, 0.25 mmol), and potassium carbonate (0.1 g, 0.72 mmol) were added to a flask. Toluene (1 mL), ethanol (0.5 mL), deionized water (0.5 mL), and Pd(PPh3)2Cl2 (5 mg) were then added. The mixture was refluxed under nitrogen for 5 h. TLC indicated the reaction was complete. The mixture was cooled, the precipitated solid was filtered, and then washed with deionized water and ethanol. The filter cake was dissolved in 5 mL of chlorobenzene under reflux. While hot, it was passed through a small amount of silica gel, rinsed with chlorobenzene, and concentrated to near dryness. The precipitated solid was filtered and rinsed with ethanol to obtain 0.21 g of a light yellow solid, with a yield of 74.1%. MALDI-TOF (m / z): M calcdfor: C 88 H 65 N,1135.5117,found,1135.5162.Elem.Anal.:C,93.00;H,5.77;N,1.23;found,C,93.07;H,5.68,N,1.25.

[0126] Example 3 Synthesis of Compound 3

[0127]

[0128] The preparation of intermediate 1 is described in Example 1.

[0129] Preparation of 3,3'-dibromotriphenylamine

[0130] Aniline (1.0 g, 10.74 mmol), m-fluorobromobenzene (3.9 g, 22.29 mmol), and potassium carbonate (4.5 g, 32.56 mmol) were added to a single-necked flask. DMF (20 mL) was added and stirred at 120°C for 5 h. TLC indicated the reaction was complete. The mixture was cooled to 80-90°C and deionized water (20 mL) was added dropwise. The mixture was stirred to precipitate a solid, which was filtered and then rinsed with deionized water and ethanol. The filter cake was added toluene (30 mL) and heated under reflux to dissolve the solid. 20 mL of toluene was concentrated to remove the toluene. The mixture was cooled and stirred to crystallize. Ethanol (10 mL) was added dropwise and stirred for 0.5 h. The mixture was then filtered, rinsed with ethanol, and dried to obtain 3.2 g of a white solid with a yield of 74.4%. 1 H NMR (400MHz, CDCl3, δ): 7.46 (t, J=2.0Hz, 2H), 7.37-7.40 (m, 4H), 7.31-7.33 (m, 2H), 7.22-7.26 (m, 4H), 7.16-7.20 (m, 1H).

[0131] Synthesis of compound 3

[0132] Intermediate product 1 (0.3 g, 0.52 mmol), 3,3'-dibromotriphenylamine (0.1 g, 0.25 mmol), and potassium carbonate (0.1 g, 0.72 mmol) were added to a flask. Toluene (1 mL), ethanol (0.5 mL), deionized water (0.5 mL), and Pd(PPh3)2Cl2 (5 mg) were added. The mixture was refluxed under nitrogen for 5 h. TLC indicated that the reaction was complete. The mixture was cooled, the solid precipitated, filtered, and washed with deionized water and ethanol in sequence. The filter cake was dissolved in 5 mL of chlorobenzene under reflux, and while hot, it was passed through a small amount of silica gel, rinsed with chlorobenzene, and concentrated to near dryness. The solid precipitated, filtered, and rinsed with ethanol to obtain a light yellow solid. MALDI-TOF (m / z): M calcd for: C 88 H 67 N,1137.5274,found,1137.5266.

[0133] Example 4 Synthesis of Compound 4

[0134]

[0135] The preparation of intermediate 1 is described in Example 1.

[0136] Synthesis of compound 4

[0137] Intermediate 1 (0.3 g, 0.52 mmol), 2,7-dibromo-9-phenylcarbazole (0.1 g, 0.25 mmol), and potassium carbonate (0.1 g, 0.72 mmol) were added to a flask. Toluene (1 mL), ethanol (0.5 mL), deionized water (0.5 mL), and Pd(PPh3)2Cl2 (5 mg) were then added. The mixture was refluxed under nitrogen for 5 h. TLC indicated the reaction was complete. The mixture was cooled, the precipitated solid was filtered, and then washed with deionized water and ethanol. The filter cake was dissolved in 5 mL of chlorobenzene under reflux. While still hot, it was passed through a small amount of silica gel, rinsed with chlorobenzene, and concentrated to near dryness. The precipitated solid was filtered and rinsed with ethanol to obtain 0.18 g of a pale yellow solid, with a yield of 64.3%. MALDI-TOF (m / z): M calcdfor: C 88 H 65 N,1135.5117,found,1135.5143.

[0138] Example 5 Synthesis of Compound 5

[0139]

[0140] Synthesis of intermediate 2

[0141] Raw material 2 (2.0 g, 3.60 mmol), bipyraclostrobin (1.1 g, 4.33 mmol) and sodium acetate (0.9 g, 10.97 mmol) were added to a flask, and anhydrous toluene (20 mL) and Pd(PPh3)2Cl2 (20 mg) were added. The mixture was refluxed under nitrogen for 8 h. TLC showed that the reaction was complete. Heating was stopped, and the mixture was passed through a small amount of silica gel while hot, rinsed with toluene, and concentrated to near dryness. 2 mL of ethanol was added and stirred to precipitate a solid, which was filtered and rinsed with ethanol to obtain a light yellow solid 2.03 with a yield of 93.5%. 1 H NMR (400MHz, CDCl3, δ):7.72-7.75(m,2H),7.57-7.60(m,2H),7.48-7.52(m,3H),7.39-7.46(m ,10H),7.33-7.38(m,3H),7.05(s,1H),1.95-2.04(m,4H),1.24(s,12H),0.94(t,J=4.4Hz,6H).

[0142] Synthesis of compound 5

[0143] Intermediate product 2 (0.3 g, 0.50 mmol), 4,4'-dibromotriphenylamine (0.1 g, 0.248 mmol), and sodium carbonate (0.08 g, 0.75 mmol) were added to a flask. Toluene (1 mL), ethanol (0.5 mL), deionized water (0.5 mL), and Pd(PPh3)2Cl2 (3 mg) were then added. The mixture was refluxed under nitrogen for 3 h. TLC indicated the reaction was complete. The mixture was cooled, the precipitated solid was filtered, and then washed with deionized water and ethanol. The filter cake was dissolved in 5 mL of chlorobenzene under reflux. While hot, it was passed through a small amount of silica gel, rinsed with chlorobenzene, and concentrated to near dryness. The precipitated solid was filtered and rinsed with ethanol to obtain 0.21 g of a pale yellow solid in a 70.9% yield. MALDI-TOF (m / z): M calcdfor: C 92 H 75 N,1193.5900,found,1193.5852.

[0144] Example 6 Synthesis of Compound 6

[0145]

[0146] Synthesis of intermediate 3

[0147] Raw material 3 (2.0 g, 3.07 mmol), pinacol diboronate (0.94 g, 3.70 mmol), and zinc acetate (1.69 g, 9.2 mmol) were added to a flask. Anhydrous toluene (24 mL) and Pd(PPh3)2Cl2 (30 mg) were added. The mixture was refluxed under nitrogen for 3 h. TLC indicated completion of the reaction. Heating was discontinued, and the mixture was passed through a small amount of silica gel while still hot, eluting with toluene. The mixture was concentrated to near dryness and stirred with 2 mL of ethanol. The precipitated solid was filtered and rinsed with ethanol to obtain 1.95 g of a light yellow solid, with a yield of 91.1%. HRMS (ESI, m / z): [M+H] + calculated for C 51 H 44 BO2,699.3429,found 699.3425.

[0148] Synthesis of compound 6

[0149] Intermediate product 3 (0.36 g, 0.52 mmol), 4,4'-dibromotriphenylamine (0.1 g, 0.248 mmol), and potassium bicarbonate (0.075 g, 0.75 mmol) were added to a flask. Toluene (1 mL), ethanol (0.5 mL), deionized water (0.5 mL), and Pd(PPh3)2Cl2 (3 mg) were then added. The mixture was refluxed under nitrogen for 8 h. TLC indicated the reaction was complete. The mixture was cooled, the precipitated solid was filtered, and then washed with deionized water and ethanol. The filter cake was dissolved in 5 mL of chlorobenzene under reflux. While still hot, it was passed through a small amount of silica gel, rinsed with chlorobenzene, and concentrated to near dryness. The precipitated solid was filtered and rinsed with ethanol to obtain 0.25 g of a pale yellow solid, with a yield of 73.5%. MALDI-TOF (m / z): M calcdfor: C 92 H 75 N,1385.5900,found,1385.5964.

[0150] Comparative Example 1

[0151]

[0152] Compared with the structure shown in Comparative Example 1, the three benzenes at the ends of the material of the present invention can be conjugated through the ethylene double bond, with a greater degree of conjugation, and a better balance can be achieved between planarity and torsional configuration.

[0153] Experimental Example 1

[0154] Compounds 1 to 2 were subjected to TGA test, and the results were as follows: Figure 2 shown.

[0155] Depend on Figure 2 It can be seen that the thermal decomposition temperature (T d , the temperature when weight loss is 5% is 504 and 540℃ respectively. d It is 340°C. It can be seen that the thermal decomposition temperature of the material of the present invention is significantly higher than that of NPD.

[0156] Experimental Example 2

[0157] DSC test was performed on compounds 1 to 2, and the results were as follows: Figure 3 shown.

[0158] Depend on Figure 3 The glass transition temperatures of compounds 1 and 2 can be seen, and the results are shown in Table 1.

[0159] Table 1 Glass transition temperature of the compounds

[0160] Compound Glass transition temperature (℃) Compound 1 178 Compound 2 200

[0161] As can be seen from Table 1, the compounds of the present invention have a relatively high glass transition temperature, indicating that the compounds of the present invention have good thermal stability.

[0162] Experimental Example 3

[0163] Compounds 1 and 2 were tested for absorption and fluorescence spectroscopy. Figure 4 The absorption and fluorescence of compound 1 are at 350 and 445 nm, respectively, and the absorption and fluorescence of compound 2 are at 348 and 431 nm, respectively.

[0164] Experimental Example 4

[0165] Compounds 1 to 2 were subjected to cyclic voltammetry tests, and the results were as follows: Figure 5 Their oxidation potentials are 1.02 and 0.97 V, and their HOMO levels are -5.42 and -5.37 eV, respectively.

[0166] Experimental Example 5 Preparation of organic electroluminescent device

[0167] OLED was prepared using Compound 1 of Example:

[0168] (1) A transparent conductive ITO glass substrate (with an anode) (China Southern Glass Group Co., Ltd.) was washed with deionized water, ethanol, acetone, and deionized water in sequence, and then treated with oxygen plasma for 30 seconds;

[0169] (2) Spin-coating a 30 nm thick PE-DOT:PSS (structure shown below) on the ITO as the hole injection layer 130, and heating at 120°C for 20 minutes to dry the solvent;

[0170] (3) Spin-coating a 40 nm thick hole transport material 140, i.e., compound 1 of the present invention, on the hole injection layer, and heating at 120° C. for 20 minutes to dry the solvent;

[0171] (4) Evaporation of Alq3 (structure shown below) to form a 20 nm thick light-emitting layer;

[0172] (5) Evaporation of 30 nm thick TmPyPB (structure shown below) as an electron transport layer;

[0173] (6) Evaporate 1 nm LiF as the electron injection layer and 100 nm Al as the device cathode.

[0174] The prepared device (schematic diagram see Figure 1 )The maximum power efficiency measured using a Photo Research PR650 spectrometer is shown in Table 2.

[0175]

[0176] Table 2 Current efficiency of devices made with compound 1

[0177]

[0178] As can be seen from Table 2, the current efficiency of the device made from the example compounds of the present invention is relatively high, which shows that the compounds of the present invention have good hole transport performance.

[0179] In summary, the hole transport materials described in the present invention can be used in organic electroluminescent devices to reduce operating voltage and improve device efficiency, resulting in excellent hole transport materials. Furthermore, the compounds of the present invention exhibit high stability, and the organic electroluminescent devices prepared therefrom exhibit high efficiency and light purity.

Claims

1. A hole transport material, which is selected from at least one of the compounds represented by formula (1): Formula (1) In formula (1), Ar1 and Ar2 are each independently selected from phenyl, naphthyl, biphenyl, phenanthrenyl, dibenzofuranyl, dibenzothiophenyl or 9,9-dimethylfluorenyl, and repeated Ar1 or Ar2 are the same or different; R1 and R2 are each independently selected from hydrogen, C1-C10 alkyl or C6-C10 aryl, and repeated R1 or R2 are the same or different; R is selected from aniline, diphenylamine, or the structure shown in formula (2) or formula (3):

2. The hole transport material according to claim 1, characterized in that In formula (1), R1 and R2 are each independently selected from hydrogen, a C1-C5 alkyl group or a C6-C10 aryl group, and repeated R1 or R2 are the same or different; R is selected from the structure shown in formula (2) or formula (3).

3. The hole transport material according to claim 1, characterized in that In formula (1), Ar1 and Ar2 are each independently selected from phenyl, R1 and R2 are each independently selected from hydrogen, methyl, ethyl, tert-butyl, phenyl, naphthyl or phenanthrenyl, and repeated R1 or R2 are the same or different; R is selected from the structure shown in formula (2) or formula (3).

4. The hole transport material according to any one of claims 1 to 3, characterized in that The compound represented by formula (1) is represented by formula (4) or formula (5): Formula (4) Formula (5); Wherein, R1 and R2 have the same definitions as in formula (1).

5. A method for preparing a hole transport material, for preparing the hole transport material according to any one of claims 1 to 4, the method comprising: Using the compound represented by formula (6), biboronic acid pinacol ester and the compound represented by formula (7) as raw materials to react and obtain the hole transport material; ； in: In formula (6), X1 is selected from halogen; Ar1 ​​and Ar2 are as described in any one of claims 1 to 4; R1 and R2 are as described in any one of claims 1 to 4; In formula (7), X2 is selected from halogen, and R is selected from aniline, diphenylamine, or the structure shown in formula (2) or formula (3): 。 6. The preparation method according to claim 5, characterized in that In formula (6), X1 is selected from chlorine, bromine or iodine; and / or, in formula (7), X2 is selected from chlorine, bromine or iodine, and R is selected from the structure shown in formula (2) or formula (3).

7. The preparation method according to claim 5, characterized in that In formula (6), X1 is selected from bromine or iodine; and / or, in formula (7), X2 is selected from bromine or iodine, and R is selected from the structure shown in formula (2) or formula (3).

8. The preparation method according to claim 5 or 6, characterized in that: The preparation method comprises the following steps: Step 1: Mix the compound represented by formula (6), pinacol diborate and base I, add solvent I and catalyst I, heat to react, and obtain an intermediate product through post-treatment; Step 2: Mix the intermediate product, the compound represented by formula (7) and base II, add solvent II and catalyst II, heat to react, and obtain the hole transport material through post-treatment.

9. The preparation method according to claim 8, characterized in that The molar ratio of the compound represented by formula (6) to the diboric acid pinacol ester is 1:(1-1.5); and / or, The molar ratio of the compound represented by formula (7) to the intermediate product is 1:(2.0-2.2).

10. The preparation method according to claim 8, characterized in that The molar ratio of the compound represented by formula (6) to the diboric acid pinacol ester is 1:(1.1-1.3); and / or, The molar ratio of the compound represented by formula (7) to the intermediate product is 1:(2.05~2.1).

11. The preparation method according to claim 8, characterized in that In step 1, the catalyst I is selected from a palladium-based catalyst; and / or, In step 1, the weight ratio of the catalyst I to the compound represented by formula (6) is (0.005-0.03):1; and / or, In step 1, the base I is selected from at least one of potassium acetate, sodium acetate, zinc acetate, and magnesium acetate; and / or, In step 1, the molar ratio of the compound represented by formula (6) to the base I is 1: (2-4); and / or, In step 1, heating to reflux for reaction, the reaction is carried out for 1 to 10 hours; and / or, In step 1, the post-treatment includes: passing through a silica gel column, washing and crystallization.

12. The preparation method according to claim 8, characterized in that In step 1, the catalyst I is selected from at least one of tris(dibenzylideneacetone)dipalladium Pd2(dba)3, palladium acetate Pd(OAc)2, 1,1'-bis(diphenylphosphinoferrocenepalladium dichloride) PdCl2(dppf), and Pd / C; and / or, In step 1, the weight ratio of the catalyst I to the compound represented by formula (6) is (0.005-0.015):1; and / or, In step 1, the molar ratio of the compound represented by formula (6) to the base I is 1: (2-3).

13. The preparation method according to claim 8, characterized in that In step 2, the catalyst II is selected from a palladium-based catalyst; and / or, In step 2, the weight ratio of the catalyst II to the intermediate product is (0.005-0.04):1; and / or, In step 2, the base II is selected from at least one of potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate; and / or, In step 2, the molar ratio of the base II to the intermediate is 1: (0.1-3); and / or, In step 2, heating to reflux to carry out the reaction, the reaction is carried out for 1 to 10 hours; and / or, In step 2, the post-treatment includes: cooling and crystallizing, dissolving the crystals and passing them through a silica gel column, washing, and crystallizing again.

14. The preparation method according to claim 8, characterized in that In step 2, the catalyst II is selected from at least one of tris(dibenzylideneacetone)dipalladium Pd2(dba)3, palladium acetate Pd(OAc)2, 1,1'-bis(diphenylphosphinoferrocene)palladium dichloride PdCl2(dppf), and Pd(PPh3)4; and / or, In step 2, the weight ratio of the catalyst II to the intermediate product is (0.008-0.03):1; and / or, In step 2, the molar ratio of the base II to the intermediate is 1: (0.3-2).

15. An organic electroluminescent device comprising an anode, a cathode, and an organic layer, wherein the organic layer comprises at least one of a light-emitting layer, a hole injection layer, a hole transport layer, a hole blocking layer, an electron injection layer, and an electron transport layer, wherein: At least one of the organic layers is made of raw materials including the hole transport material according to any one of claims 1 to 4 or the hole transport material obtained by the preparation method according to any one of claims 5 to 14.

16. The organic electroluminescent device according to claim 15, characterized in that: The organic layer includes, in sequence, a hole injection layer, a hole transport layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer, wherein the hole injection layer and / or the hole transport layer in the organic layer is made of raw materials including the hole transport material according to any one of claims 1 to 4 or the hole transport material obtained by the preparation method according to any one of claims 5 to 14.

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