An organic compound and its preparation method and organic electroluminescent device

Abstract

The present invention provides an organic compound and a preparation method thereof and an organic electroluminescent device, belonging to the technical field of luminescent materials. The organic compound provided by the present invention is a compound with fluorene as a parent core and triarylamine as a functional group, which can be used as a luminescent auxiliary layer of green and red organic electroluminescent devices. The compound can reduce the potential barrier between the hole transport layer and the luminescent layer, reduce the driving voltage of the organic electroluminescent device, further improve the hole transport rate, and the electron blocking ability, thereby greatly improving the life and luminescence efficiency of the device.

Description

[0001] This invention is a divisional application of the Chinese invention patent application with application number 202211231175.4, application date October 10, 2022, and invention name “An organic compound, preparation method thereof and organic electroluminescent device”. Technical Field

[0002] The present invention relates to the technical field of luminescent materials, and more particularly to an organic compound and a preparation method thereof, and an organic electroluminescent device. Background Art

[0003] Organic electroluminescent display (OLED) is an active light-emitting display device. It has the characteristics of self-luminescence, bright colors, thin thickness, light weight, fast response speed, wide viewing angle, low driving voltage, tolerance to harsh natural conditions, and can be made into flexible panels. At present, small and medium-sized OLED display screens have been widely used in a variety of high-end smartphones. Obtaining the best luminous efficiency of the device under low operating voltage conditions is a common demand in the OLED field.

[0004] Many improvements have been made to bring organic EL devices to practical use. For example, it is known that high efficiency and high durability can be achieved by further allocating the various roles of the laminated structure and forming an anode, a hole injection layer, a hole transport layer, a hole blocking layer, a light-emitting layer, an electron transport layer, an electron injection layer and a cathode on a substrate.

[0005] With this organic EL device, the charges injected from the two electrodes are recombined in the light-emitting layer to obtain light emission. In this case, how to effectively transfer the charges of holes and electrons to the light-emitting layer is important, and the device needs to have excellent carrier balance. Moreover, by enhancing the hole injection characteristics and electron blocking characteristics of blocking the electrons injected from the cathode to increase the recombination probability of holes and electrons, and by limiting the excitons generated in the light-emitting layer, the luminous efficiency is improved. Therefore, the role of the luminescent auxiliary material is so important.

[0006] Research on organic electroluminescent materials has been widely carried out in academia and industry, but so far, stable and efficient organic layer materials for organic electrical components have not been fully developed, and the industrialization process of this technology still faces many key problems. Therefore, how to develop a new luminescent auxiliary material has always been a problem that technicians in this field need to solve urgently. Summary of the invention

[0007] In view of this, one of the purposes of the present invention is to provide a novel organic compound; the second purpose is to provide a method for synthesizing the novel organic compound; the third purpose is to provide an organic electroluminescent device using the novel organic compound.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] An organic compound, the molecular formula of which is shown in general formula (I):

[0010]

[0011] Where:

[0012] L is selected from substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C6-C30 heteroaryl, wherein the heteroatom is selected from oxygen, nitrogen, and sulfur;

[0013] R 1 -R 4 are the same as or different from each other and are each independently selected from hydrogen, deuterium, substituted or unsubstituted C1-C15 alkane, substituted or unsubstituted C1-C18 cycloalkane, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C6-C30 heteroaryl, wherein the heteroatom is selected from oxygen, nitrogen and sulfur.

[0014] It is further preferred that: L is selected from substituted or unsubstituted phenyl, and when substituted, the substituent is selected from hydrogen, phenyl, C1-C10 alkyl;

[0015] R 1 -R 4 are the same as or different from each other and are each independently selected from hydrogen, deuterium, substituted or unsubstituted C1-C10 alkane, substituted or unsubstituted C1-C12 cycloalkane, substituted or unsubstituted C6-C20 aryl, substituted or unsubstituted C6-C20 heteroaryl, wherein the heteroatom is selected from oxygen, nitrogen, and sulfur.

[0016] In the present specification, "substituted" means substituted by one, two or more substituents selected from the following: hydrogen, C1-C20 alkyl, C1-C20 alkoxy, C6-C30 aryl, C6-C30 heteroaryl, wherein the heteroatom is selected from oxygen, nitrogen, sulfur.

[0017] Furthermore, the polycyclic aromatic compounds are selected from any one of the compounds represented by the following structural formulas:

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024] Another object of the present invention is to provide a method for preparing the above-mentioned luminescent auxiliary material. The synthetic route of formula I is:

[0025]

[0026] Where R 1 -R 4 , L are as defined above; Hal 1 is selected from fluorine, chlorine, bromine and iodine;

[0027] After raw materials a and b were dissolved in toluene, 2 Add Pd under atmosphere 2 (dba) 3 、P(t-Bu) 3 and t-BuONa, heating to 110-120°C and stirring for reaction for 10-12h. After the reaction is completed, diatomaceous earth is used for hot filtration to remove salt and catalyst. After the filtrate is cooled to room temperature, distilled water is added to the filtrate for washing. After separation, the organic phase is retained, the aqueous phase is extracted with ethyl acetate, and then the combined organic layer is dried with magnesium sulfate, and the solvent is removed with a rotary evaporator. Finally, a mixture of dichloromethane and petroleum ether is used as an eluent, and the remaining substance is purified by column chromatography to obtain a compound shown in general formula I.

[0028] An organic electroluminescent device comprises: an organic layer; the organic layer comprises a light-emitting auxiliary layer, and the light-emitting auxiliary layer comprises the above-mentioned organic compound.

[0029] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention provides a compound with fluorene as a parent core and triarylamine functional groups, which can be used as a light-emitting auxiliary layer of a green light and red light organic electroluminescent device. The compound can reduce the potential barrier between the hole transport layer and the light-emitting layer, reduce the driving voltage of the organic electroluminescent device, further improve the hole transport rate and the electron blocking ability, increase the charge balance of holes and electrons in the light-emitting layer, so that light is well formed inside the light-emitting layer instead of on the surface of the hole transport layer, thereby greatly improving the life and light-emitting efficiency of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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 only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0032] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of Example 1 of the present invention. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035]

[0036] The raw material a (20.00 mmol) and the raw material b (20.00 mmol) were dissolved in toluene and heated under N 2 Add Pd under atmosphere 2 (dba) 3 (0.4mmol), P(t-Bu) 3 (1.0mmol) and t-BuONa (40.00mmol), heated to 120℃ and stirred for reaction for 10h. After the reaction, diatomaceous earth was used for hot filtration to remove salt and catalyst. After the filtrate was cooled to room temperature, distilled water was added to the filtrate for washing. After separation, the organic phase was retained, the aqueous phase was extracted with ethyl acetate, and then the combined organic layer was dried with magnesium sulfate, and the solvent was removed with a rotary evaporator. Finally, a mixture of dichloromethane and petroleum ether (V:V=1:10) was used as an eluent, and the remaining substance was purified by column chromatography to obtain the compound shown in compound 11; (10.85g, yield: 86.25%, Mw: 629.80);

[0037] Mass spectrometry test: theoretical value is 629.80; tested value is 629.65.

[0038] Elemental Analysis:

[0039] Calculated values: C, 89.63; H, 5.60; N, 2.72; O, 2.54.

[0040] The test values ​​are: C, 88.86; H, 5.76; N, 2.94; O, 2.78.

[0041] Example 2

[0042] The raw material b in Example 2 needs to be synthesized according to the following reaction.

[0043]

[0044] The raw material 1 (1.0 eq) and the raw material 2 (1.0 eq) were dissolved in toluene and heated under N 2 Add Pd under atmosphere 2 (dba) 3 (0.02eq), P(t-Bu) 3 (0.05eq) and t-BuONa (2.0eq), heated to 120°C and stirred for reaction for 10h to prepare raw material b.

[0045]

[0046] The raw material a (20.00 mmol) and the raw material b (20.00 mmol) were dissolved in toluene and heated under N 2 Add Pd under atmosphere 2 (dba) 3 (0.4mmol), P(t-Bu) 3 (1.0mmol) and t-BuONa (40.00mmol), heated to 120℃ and stirred for reaction for 10h. After the reaction, diatomaceous earth was used for hot filtration to remove salt and catalyst. After the filtrate was cooled to room temperature, distilled water was added to the filtrate for washing. After separation, the organic phase was retained, the aqueous phase was extracted with ethyl acetate, and then the combined organic layer was dried with magnesium sulfate, and the solvent was removed with a rotary evaporator. Finally, a mixture of dichloromethane and petroleum ether (V:V=1:10) was used as an eluent, and the remaining substance was purified by column chromatography to obtain the compound shown in Compound 83; (11.29g, yield: 80.05%, Mw: 705.90);

[0047] Mass spectrometry test: theoretical value is 705.90; tested value is 705.67.

[0048] Elemental Analysis:

[0049] Calculated values: C, 90.18; H, 5.57; N, 1.98; O, 2.27.

[0050] The test values ​​are: C, 89.68; H, 5.79; N, 2.22; O, 2.39.

[0051] Example 3

[0052] The raw material b in Example 3 needs to be synthesized according to the following reaction.

[0053]

[0054] The raw material 1 (1.0 eq) and the raw material 2 (1.0 eq) were dissolved in toluene and heated under N 2 Add Pd under atmosphere 2 (dba) 3 (0.02eq), P(t-Bu) 3 (0.05eq) and t-BuONa (2.0eq), heated to 120°C and stirred for reaction for 10h to prepare raw material b.

[0055]

[0056] The raw material a (20.00 mmol) and the raw material b (20.00 mmol) were dissolved in toluene and heated under N 2 Add Pd under atmosphere 2 (dba) 3 (0.4mmol), P(t-Bu) 3 (1.0mmol) and t-BuONa (40.00mmol), heated to 120℃ and stirred for reaction for 10h. After the reaction, diatomaceous earth was used for hot filtration to remove salt and catalyst. After the filtrate was cooled to room temperature, distilled water was added to the filtrate for washing. After separation, the organic phase was retained, the aqueous phase was extracted with ethyl acetate, and then the combined organic layer was dried with magnesium sulfate, and the solvent was removed with a rotary evaporator. Finally, a mixture of dichloromethane and petroleum ether (V:V=1:10) was used as an eluent, and the remaining substance was purified by column chromatography to obtain the compound shown in Compound 83; (11.04g, yield: 78.26%, Mw: 705.90);

[0057] Mass spectrometry test: theoretical value is 705.90; tested value is 706.11.

[0058] Elemental Analysis:

[0059] Calculated values: C, 90.18; H, 5.57; N, 1.98; O, 2.27.

[0060] The test values ​​are: C, 89.61; H, 5.77; N, 2.18; O, 2.45.

[0061] Example 4

[0062] In Example 4, raw material a requires the following three steps for synthesis:

[0063]

[0064] The raw material a-1 (1.0 eq) was dissolved in THF, then ventilated 3 times, cooled to -78°C, n-BuLi (2.0 eq) was slowly added, and the reaction was continued for 4 h. The raw material a-2 (1.0 eq) was added under nitrogen protection, the temperature was slowly raised to 25°C, and stirred for 12 h to prepare the intermediate a-3.

[0065] The raw material a-3 (1.0 eq) was dissolved in a mixed solvent of THF and toluene (V:V=1:1), MSA (10.0 eq) was slowly added to the above mixture, and stirred at room temperature for 8 h to prepare the raw material a-4.

[0066] The raw material a-4 (1.0 eq) was dissolved in THF solution, iodomethane (5.0 eq) and potassium tert-butoxide (5.0 eq) were added, and the mixture was stirred at room temperature for 10 h to prepare the raw material a.

[0067]

[0068] The raw material 1 (1.0 eq) and the raw material 2 (1.0 eq) were dissolved in toluene and heated under N 2 Add Pd under atmosphere 2 (dba) 3 (0.02eq), P(t-Bu) 3 (0.05eq) and t-BuONa (2.0eq), heated to 120°C and stirred for reaction for 10h to prepare raw material b.

[0069]

[0070] The raw material a (20.00 mmol) and the raw material b (20.00 mmol) were dissolved in toluene and heated under N 2 Add Pd under atmosphere 2 (dba) 3 (0.4mmol), P(t-Bu) 3 (1.0mmol) and t-BuONa (40.00mmol), heated to 120℃ and stirred for reaction for 10h. After the reaction, diatomaceous earth was used for hot filtration to remove salt and catalyst. After the filtrate was cooled to room temperature, distilled water was added to the filtrate for washing. After separation, the organic phase was retained, the aqueous phase was extracted with ethyl acetate, and then the combined organic layer was dried with magnesium sulfate, and the solvent was removed with a rotary evaporator. Finally, a mixture of dichloromethane and petroleum ether (V:V=1:10) was used as an eluent, and the remaining substance was purified by column chromatography to obtain the compound shown in compound 122; (10.84g, yield: 75.34%, Mw: 719.93);

[0071] Mass spectrometry test: theoretical value is 719.93; tested value is 719.75.

[0072] Elemental Analysis:

[0073] Calculated values: C, 90.09; H, 5.74; N, 1.95; O, 2.22.

[0074] The test values ​​are: C, 89.57; H, 5.94; N, 2.18; O, 2.46.

[0075] Since the general structural formula is Formula 1 in the content of the invention, the synthesis routes and principles of other compounds are the same as those of the above-mentioned embodiments, so they are not listed here in detail. According to the above preparation method, the luminescent auxiliary material shown in Table 1 below can be obtained:

[0076] Table 1:

[0077]

[0078]

[0079] The organic electroluminescent device prepared by using the luminescence auxiliary material provided in the above embodiment, when the organic layer includes a luminescence auxiliary layer, the luminescence auxiliary layer includes the luminescence auxiliary material (organic compound) provided in the above embodiment.

[0080] Device Example 1 (Green Light Device)

[0081] (1) ITO anode: The ITO (indium tin oxide)-Ag-ITO (indium tin oxide) glass substrate with a coating thickness of 150nm was washed twice in distilled water, ultrasonically washed for 30 minutes, and then repeatedly washed twice with distilled water, ultrasonically washed for 10 minutes. After washing, it was transferred to a spin dryer for drying, and finally baked in a vacuum oven at 220°C for 2 hours. After baking, it was cooled down and used. With this substrate as the anode, a vapor deposition machine was used to carry out the vapor deposition device process, and other functional layers were sequentially vapor deposited on it.

[0082] (2)HIL (hole injection layer): The hole injection layer materials HT and P-dopant are vacuum evaporated at a deposition rate of 97:3, and the thickness is 10 nm;

[0083] (3) HTL (hole transport layer): At a deposition rate of 100%, 120 nm of HT was vacuum-deposited on the hole injection layer as a hole transport layer.

[0084] (4) Light-emitting auxiliary layer: At a deposition rate of , 45 nm of the compound 11 provided in the above embodiment is vacuum-deposited on the hole transport layer as a light-emitting auxiliary layer;

[0085] (5) EML (light-emitting layer): Then on the above-mentioned light-emitting auxiliary layer, The evaporation rate of the main material (Host-1 and Host-2) and the dopant material (Dopant) with a thickness of 400nm are vacuum evaporated as the light-emitting layer, wherein Host-1 and Host-2 are co-evaporated as dual main materials with the dopant material, and the ratio of Host-1 to Host-2 is 50%:50%. The chemical formulas of Host-1, Host-2 and Dopant are shown below. The evaporation rate ratio of the main material and Dopant is 88:12.

[0086] (6) HBL (hole blocking layer): The hole blocking layer HBL with a thickness of 5.0 nm was vacuum-deposited at a deposition rate of .

[0087] (7) ETL (Electron Transport Layer): ET and Liq were vacuum evaporated at a deposition rate of 30 nm as an electron transport layer, where the deposition rate ratio of ET to Liq was 50:50.

[0088] (8) EIL (electron injection layer): At a evaporation rate of , a 1.0 nm Yb film layer was evaporated to form an electron injection layer.

[0089] (9) Cathode: The evaporation rate ratio of magnesium and silver is 18nm, and the evaporation rate ratio of magnesium and silver is 1:9 to form a cathode.

[0090] (10) Light extraction layer: At a deposition rate of , CPL with a thickness of 70 nm was vacuum-deposited on the cathode as a light extraction layer.

[0091] (11) Encapsulating the substrate after evaporation. First, the cleaned cover plate is coated with UV glue using a glue coating device, and then the coated cover plate is moved to the pressing section, the evaporation-deposited substrate is placed on the upper end of the cover plate, and finally the substrate and the cover plate are bonded by the bonding device, and the UV glue is cured by light.

[0092] The compounds used in each layer are as follows:

[0093]

[0094] Device Comparison Example 1:

[0095] This comparative example provides an organic electroluminescent device. The only difference between the preparation method of the organic electroluminescent device and the device embodiment 1 is that the organic electroluminescent device uses existing comparative compounds a, b, c, d, e, f, g, h, i, and j to replace the luminescent auxiliary material (compound 11) in the above device embodiment 1 for evaporation to prepare device comparative examples 1-10. Among them, the chemical structural formulas of comparative compounds a, b, c, d, e, f, g, h, i, and j are:

[0096]

[0097]

[0098] The performance of the organic electroluminescent devices prepared in the test application examples and comparative examples was characterized at a brightness of 15000 (nits) for the luminous efficiency and life of the organic electroluminescent devices obtained in the device embodiments 1-25 and the device comparative examples 1-10. The test results are shown in Table 2 below:

[0099] Table 2 Luminous characteristics test results (brightness value is 15000nits)

[0100]

[0101]

[0102]

[0103] Device application example 26 (red light device)

[0104] The structure of the prepared OLED device is: ITO anode / HIL / HTL / luminescent auxiliary layer

[0105] / EML / HBL / ETL / EIL / Cathode / Light Extraction Layer

[0106] a. ITO anode: the coating thickness is The ITO (indium tin oxide)-Ag-ITO (indium tin oxide) glass substrate was cleaned twice in distilled water, ultrasonically cleaned for 30 minutes, and then repeatedly cleaned twice with distilled water, ultrasonically cleaned for 10 minutes. After washing, it was ultrasonically cleaned with methanol, acetone, and isopropanol in sequence (5 minutes each time), dried, and then transferred to a plasma cleaning machine for washing for 5 minutes. It was then sent to a vapor deposition machine, and the substrate was used as the anode, and other functional layers were deposited thereon in sequence.

[0107] b. HIL (hole injection layer): The hole injection layer materials HT-1 and P-dopant are vacuum evaporated at a deposition rate of 97:3, and the thickness is 10 nm;

[0108] c. HTL (hole transport layer): At a deposition rate of 100%, 130 nm of HT-1 was vacuum-deposited on the hole injection layer as a hole transport layer.

[0109] d. Light-emitting auxiliary layer: At a deposition rate of , 10 nm of the compound 11 provided in the above embodiment is vacuum-deposited on the hole transport layer as a light-emitting auxiliary layer;

[0110] e. EML (light-emitting layer): Then on the above-mentioned light-emitting auxiliary layer, The evaporation rate of the main material (Host-1) and the dopant material (Dopant-1) with a thickness of 20nm are vacuum evaporated as the light-emitting layer. The chemical formulas of Host-1 and Dopant-1 are shown below. The evaporation rate ratio of the double Host-1 and Dopant-1 is 98:2.

[0111] f. HBL (hole blocking layer): The hole blocking layer HB with a thickness of 5.0 nm was vacuum deposited at a deposition rate of .

[0112] g. ETL (Electron Transport Layer): At a deposition rate of , ET-1 and Liq with a thickness of 35 nm were vacuum-deposited as an electron transport layer, and the chemical formula of ET-1 is shown below. The deposition rate ratio of ET-1 to Liq is 50:50.

[0113] h. EIL (electron injection layer): At a evaporation rate of , a 1.0 nm Yb film layer was evaporated to form an electron injection layer.

[0114] i. Cathode: The evaporation rate ratio is 1:9, and magnesium and silver are evaporated at 18nm, and the evaporation rate ratio is 1:9 to obtain an OLED device.

[0115] j. Light extraction layer: At a deposition rate of , CPL-1 with a thickness of 70 nm was vacuum-deposited on the cathode as a light extraction layer.

[0116] K. Then the vapor-deposited substrate is packaged. First, the cleaned cover is coated with UV glue using glue coating equipment, and then the coated cover is moved to the pressing section, the vapor-deposited substrate is placed on the upper end of the cover, and finally the substrate and cover are bonded by bonding equipment, and the UV glue is cured by light.

[0117]

[0118] Device Comparison Example 11:

[0119] This comparative example provides an organic electroluminescent device. The only difference between the preparation method of the organic electroluminescent device and the device embodiment 26 is that the organic electroluminescent device uses existing comparative compounds a, b, c, d, e, f, g, h, i, j to replace the luminescent auxiliary material (compound 11) in the above device embodiment 26 for evaporation to prepare device comparative examples 11-20. Among them, the chemical structural formulas of comparative compounds a, b, c, d, e, f, g, h, i, j are:

[0120]

[0121]

[0122] The driving voltage, luminous efficiency and life of the organic electroluminescent devices obtained from the device embodiments 26 to 50 and the device comparative examples 11 to 20 were characterized at a brightness of 6000 (nits). The test results are shown in Table 3 below:

[0123] Table 3:

[0124]

[0125]

[0126] According to the results in Table 2, in the green light device structure, the comparison compound a is parallel to the compounds 17, b and 24, indicating that the device performance can be improved when the parent core is phenylfluorene. The comparison compound c is similar to the structure of the present invention, indicating that the L bridging group is phenyl, tolyl and biphenyl, which can better improve the device performance. The comparison compound d is parallel to the compound 95, the comparison compound h is parallel to the compound 89, and the comparison compound e is parallel to the compound 27, indicating that the side chain is dibenzofuran and dibenzofluorene, which can better improve the device performance in the green light device structure than other groups.

[0127] According to the results in Table 3, the comparison of compound h and compound 89 in the red light device structure is a parallel comparison, which proves that the device performance can be improved when the side chain substituents in the red light device structure are not fused.

[0128] In summary, compared with the organic electroluminescent devices prepared in Comparative Examples 1 to 20, the driving voltage, luminous efficiency and life of the organic electroluminescent devices in Examples 1 to 50 using the organic electroluminescent compounds of the present invention as the luminescent auxiliary layer are improved, and can be applied to both green organic electroluminescent devices and red organic electroluminescent devices. In the red and green devices used in the present invention, the luminous efficiency is increased by 4 to 7%, which is a significant improvement.

[0129] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0130] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An organic compound, characterized in that The organic compound includes any one of the following structures:

2. An organic electroluminescent device, characterized in that: include: An organic layer; the organic layer comprises a light-emitting auxiliary layer, and the light-emitting auxiliary layer comprises the organic compound according to claim 1.

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