A compound containing carbazole structure and an organic electroluminescent device

Abstract

The invention discloses a compound and an organic electroluminescent device containing a carbazole structure, and relates to the field of organic electroluminescent technology. The compound in the present invention is appropriately substituted on the carbazole group so that the compound molecular weight is between 560-650, and the compound of the molecular weight in this interval has a suitable evaporation temperature and sublimation temperature, which ensures the evaporation mass production and evaporation stability of the product. At the same time, the molecular weight in this interval can be well mixed with N-type (electron transmission type host material) on the market to form a dual host material for use, thereby improving the stability and mass production of the device. The compound in the present invention has a suitable melting point due to having a relatively large torque and steric hindrance, and at the same time, a relatively large torque can improve the solubility of such materials, thereby reducing the mass production cost of such materials and improving product quality. After device verification, the device prepared using the compound of the present invention has good luminous efficiency and lifespan.

Description

Technical Field

[0001] The present invention relates to the technical field of organic electroluminescence, and in particular to a compound containing a carbazole structure and an organic electroluminescent device. Background Art

[0002] An organic photoelectric device (organic photodiode) is a device that can convert electrical energy into light energy and vice versa.

[0003] An organic light-emitting device generally has a structure including an anode, a cathode, and an organic material layer between the anode and the cathode. The organic material layer generally has a multilayer structure including different materials to improve the efficiency and stability of the organic light-emitting device, for example, the organic material layer may be formed of a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, etc. In the structure of the organic light-emitting device, if a voltage is applied between two electrodes, holes are injected from the anode into the organic material layer, electrons are injected from the cathode into the organic material layer, and when the injected holes and electrons meet each other, excitons are formed, and light is emitted when the excitons fall to the ground state again.

[0004] Organic electronic devices include but are not limited to the following categories: organic light emitting diodes (OLEDs), organic field effect transistors (O-FETs), organic light emitting transistors (OLETs), organic photovoltaic devices (OPVs), dye-sensitized solar cells (DSSCs), organic optical detectors, organic photoreceptors, organic field effect devices (OFQDs), light emitting electrochemical cells (LECs), organic laser diodes and organic plasmonic light emitting devices.

[0005] Therefore, in view of the current industrial application requirements of OLED devices and the different functional film layers of OLED devices, and the optoelectronic characteristics of the devices, it is necessary to select more suitable and higher-performance OLED functional materials or material combinations to achieve the comprehensive characteristics of high efficiency, long life and low voltage of the devices. For TTF characteristic OLED light-emitting devices, in order to pursue stable and efficient TTF light-emitting effects, there are certain requirements for the physical properties of the host and guest materials. At the same time, the host and guest materials need to have the best combination and matching form, and also require good carrier injection and good carrier balance of the light-emitting layer.

[0006] Research on improving the performance of organic electroluminescent devices includes: reducing the driving voltage of the device, improving the luminous efficiency of the device, and improving the service life of the device. In order to achieve the continuous improvement of the performance of organic electroluminescent devices, it is necessary not only to continuously research and innovate organic electrophotoelectric functional materials and create higher-performance organic electrofunctional materials, but also to innovate the structure and manufacturing process of organic electroluminescent devices, and continuously require the development of new materials for organic light-emitting devices as described above. The compounds and organic electroluminescent devices in the present invention can improve the green light luminous efficiency and life, and promote the localization of OLED materials. Summary of the invention

[0007] Purpose of the invention: In view of the above technical problems, the present invention provides a compound containing a carbazole structure and an organic electroluminescent device.

[0008] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0009] A compound, the structural formula of which is shown in the following formula (I):

[0010]

[0011] Wherein R1 is hydrogen, substituted or unsubstituted C 6-30 Aromatic or substituted or unsubstituted C 6-30 Heteroaryl, substituted by C 1-4 Alkyl or deuterium;

[0012] R2 and R3 are each independently hydrogen or substituted or unsubstituted C 6-12 The aromatic group, whose substituent is deuterium or cyano;

[0013] L is a substituted or unsubstituted phenyl group, and its substituent is deuterium, phenyl or deuterated phenyl;

[0014] When R1 is phenyl, R2 and R3 are not hydrogen at the same time.

[0015] Preferably, R1 is hydrogen, substituted or unsubstituted C 6-30 Aromatic or substituted or unsubstituted C 6-30 Heteroaryl, substituted by C 1-4 Alkyl or deuterium.

[0016] Preferably, R2 or R3 are each independently hydrogen, deuterated or undeuterated phenyl, or deuterated or undeuterated biphenyl.

[0017] More preferably, R1 is hydrogen or a substituted or unsubstituted group: biphenyl, o-terphenyl, triphenylene, triphenyl[1,12-bcd]furanyl, phenanthrenyl or phenyl, wherein the substituent is C 1-4 Alkyl or deuterium.

[0018] More preferably, R2 or R3 are each independently hydrogen, phenyl or deuterated phenyl.

[0019] More preferably, L is phenyl, deuterated phenyl, phenylphenyl or deuterated phenylphenyl.

[0020] Preferably, the structural formula of the compound of the present invention is as shown in the following formula (II):

[0021]

[0022] Furthermore, R1 is one of the following groups:

[0023]

[0024] Furthermore, the compound of the present invention is any one of the following compounds:

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039] The synthetic route of the compound is as follows:

[0040]

[0041] An organic electroluminescent device comprises a first electrode, a second electrode and an organic layer formed between the first electrode and the second electrode; wherein the organic layer contains the compound of the invention.

[0042] Furthermore, the organic layer comprises a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer; wherein the light-emitting layer contains the compound of the present invention.

[0043] Furthermore, the light-emitting layer contains a light-emitting host material, and the light-emitting host material is a mixture of any one or more of the above compounds and compounds G1-G42. Compounds G1-G42 are as follows:

[0044]

[0045]

[0046]

[0047] An electronic display device containing the organic electroluminescent device.

[0048] An OLED lighting device containing the organic electroluminescent device.

[0049] The room temperature described in the present invention is 25±5°C.

[0050] Beneficial effects of the present invention:

[0051] The present invention designs a new type of organic electroluminescent material, which is a compound formed by connecting the 4th position of a substituted or unsubstituted carbazole group with the 9th position of another substituted or unsubstituted carbazole group through an aromatic group such as a phenyl group. The compound of the present invention has the following characteristics:

[0052] 1. The compounds in the present invention are all compounds formed by connecting the No. 4 position of the carbazole group with the No. 9 position of another carbazole group through a phenyl group. The compounds obtained by this special connection method have large steric hindrance and torque, and the large steric hindrance and torque greatly increase the triplet energy level of the compound. At the same time, the two carbazoles are connected by a phenyl group, which interrupts the planarity of the compound molecule, reduces the conjugation effect of the compound molecule, and further increases the triplet energy level of the compound molecule. The relatively high triplet energy level can ensure the reverse transfer of energy from the doping material to the main material, thereby improving the utilization rate of the excitons and the luminous efficiency of the device. At the same time, the relatively low planarity significantly reduces the crystallinity of such compounds, improves the film-forming property, and thus increases the life of the device.

[0053] 2. The compounds in the present invention have a relatively large torque and steric hindrance, which results in a suitable melting point. The suitable melting point can make the materials in a molten state during evaporation, which can solve the problem of hole blocking in the current mass production of devices, improve the film-forming property of the materials, and thus improve the production stability and yield of the devices. At the same time, the relatively large torque can improve the solubility of the materials, thereby reducing the mass production cost of the materials and improving the product quality.

[0054] 3. The compounds designed by the present invention are appropriately substituted on the carbazole group so that the molecular weight of the compounds is between 560-650. The compounds with molecular weights in this range have suitable evaporation temperatures and sublimation temperatures, ensuring the mass production and stability of the evaporation of the products. At the same time, the molecular weights in this range can be well mixed with the N-type (electron transport type host material) currently on the market to form a dual host material, thereby improving the stability and mass production of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 A schematic diagram of the structure of an organic electroluminescent device provided by the present invention;

[0056] The numbers in the figure represent: 1-anode, 2-hole injection layer, 3-hole transport layer, 4-electron blocking layer, 5-light-emitting layer, 6-hole blocking layer, 7-electron transport layer, 8-electron injection layer, 9-cathode;

[0057] Figure 2 is the HPLC chart of compound 6 prepared in Example 1 of the present invention;

[0058] Figure 3 is the DSC spectrum of compound 6 prepared in Example 1 of the present invention, Figure 3 It can be seen that the Tg value of compound 6 is 208.00°C;

[0059] Figure 4 is the TGA spectrum of compound 6 prepared in Example 1 of the present invention, Figure 4 It can be seen that the thermal weight loss temperature Td value is 507.87℃;

[0060] Figure 5 is a life graph of the organic electroluminescent device in Application Example 1 and Comparative Example 1 of the present invention; Figure 5 It can be seen that the T97% lifespans of the organic electroluminescent devices prepared in Application Example 1 and Comparative Example 1 of the present invention are 610 h and 465 h, respectively. DETAILED DESCRIPTION

[0061] The following further illustrates and describes embodiments of various aspects. It should be understood that the description herein is not intended to limit the claims to the specific aspects described. On the contrary, it is intended to cover substitutions, modifications and equivalents that may be included in the spirit and scope of the present disclosure defined by the appended claims.

[0062] As used herein, in "substituted" or "unsubstituted", the term "substituted" means that at least one hydrogen in the group is re-coordinated with deuterium, a hydrocarbon group, a hydrocarbon derivative group, a halogen, or a cyano group (-CN). The term "unsubstituted" means that at least one hydrogen in the group is not re-coordinated with deuterium, a hydrocarbon group, a hydrocarbon derivative group, a halogen, or a cyano group (-CN). Examples of hydrocarbon groups or hydrocarbon derivative groups may include C1 to C30 alkyl, C2 to C30 alkenyl, C2 to C30 alkynyl, C6 to C30 aryl, C5 to C30 heteroaryl, C1 to C30 alkylamino, C6 to C30 arylamino, C6 to C30 heteroarylamino, C6 to C30 arylheteroarylamino, etc., but are not limited thereto.

[0063] The C1-C4 alkyl group in the present invention (i.e., C 1-4 Alkyl) refers to methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl; C1-C4 deuterated alkyl (i.e. C 1-4 The deuterated alkyl group refers to a group obtained by replacing any number of hydrogen atoms in a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a sec-butyl group, an isobutyl group, or a tert-butyl group with deuterium.

[0064] Deuterium in the present invention refers to a stable isotope of hydrogen, also known as heavy hydrogen, and its element symbol is D.

[0065] The aromatic group in the present invention refers to an all-carbon monocyclic or condensed polycyclic group of 6 to 30 carbon atoms, having a completely conjugated π electron system. Non-limiting examples of aromatic groups include phenyl, naphthyl, anthracenyl, biphenyl, o-terphenyl, m-terphenyl, p-terphenyl, triphenyl[1,12-bcd]furanyl, phenanthrenyl, and the like.

[0066] The heteroaryl group in the present invention refers to an aromatic group containing one or more heteroatoms such as N, O, S, and P.

[0067] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0068] Embodiment 1:

[0069]

[0070] The synthesis method of compound 6 is as follows:

[0071]

[0072] Under nitrogen protection, compound 1-a (100g, 580.72mmol, 2eq) and compound 1-b (71.46g, 290.36mmol, 1eq) were added to the reaction bottle, and DMF (800ml) and cesium carbonate (189.21g, 580.72mmol, 2eq) were added. After the addition was completed, the reaction solution was heated to 150° and reacted for 7h. After the reaction was completed and the temperature was lowered, 1000ml of water was added. Solids precipitated during the stirring process. After stirring for 20min, the filter cake was washed twice with water and ethanol, and dried. 500mL of ethanol was added, refluxed and boiled for 1h, cooled and filtered, and dried. Finally, 72g of light yellow solid 1-c was obtained, with a yield of 62.26% and a purity of 99%.

[0073] In a three-necked flask, under nitrogen protection, compound 1-d (60 g, 150.53 mmol, 1 eq, raw material 1) and compound 1-c (47.54 g, 165.58 mmol, 1.1 eq, raw material 2) were dissolved in 900 mL of toluene, potassium carbonate (52 g, 376.33 mmol, 2.5 eq), tetrakistriphenylphosphine palladium (2.61 g, 2.26 mmol, 0.015 eq) were added, and then 180 mL of ethanol and 180 mL of water were added. The reaction was stirred at 90 ° C overnight. After heating, the reaction solution became clear. The reaction progress was monitored by HPLC. The reaction was completed in 6-7 hours. After the reaction is completed and cooled, 500 ml of water is added, stirred, the reaction solution is separated and extracted, the organic phases are combined, passed through silica gel, activated carbon, anhydrous magnesium sulfate, and spin-dried into oil, 500 mL of ethanol is added, and the mixture is boiled at 90°C for 1 h. Solids precipitate, and the mixture is boiled for 1 h. The mixture is cooled and filtered. The filter cake is washed twice with ethanol and dried to obtain 74 g with a purity of 97%.

[0074] After adding 900 mL of dichloromethane (65°C) to dissolve, pass through silica gel and activated carbon, evaporate 500 mL of dichloromethane, add 40 mL of ethanol to precipitate the product, which is gray, 56 g, and has a purity of 98.5%.

[0075] After adding 350 mL of toluene (130°C) to dissolve, pass through silica gel and activated carbon, evaporate 200 mL of toluene, cool and precipitate the white product, filter and dry to obtain 38 g with a purity of 99.94%.

[0076] Take 38 g, add 500 mL of dichloromethane, dissolve at 60°C, and then evaporate 350 mL of dichloromethane to obtain compound 6 (24 g, purity 99.98%) with a yield of 28.42%.

[0077] Intermediate compounds 2-c to 31-c (ie, starting material 2) were obtained in a similar manner to that in Example 1.

[0078] The following product compounds were obtained in a similar manner:

[0079] Table 1

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089] The synthetic identification results of the compounds prepared above are shown in Table 2 below:

[0090] Table 2

[0091]

[0092] Device performance test:

[0093] The thermal weight loss temperature Td and melting point Tm of compounds 6, 7, 10, 18, 30, 31, 50, 51, 55, 62, 78, 90, 95, 103, 112, 135, 146, 147, 151, 158, 159, 160, 163, 171, 172, 175, 180, 181, 182, 186, and 187 in Examples 1-31 of the present invention were tested. The results are shown in Table 3:

[0094] Note: Thermogravimetric temperature Td is the temperature at which the weight loss is 5% in a nitrogen atmosphere, and is measured on a TGA N-1000 thermogravimetric analyzer with a nitrogen flow rate of 10 mL / min. The melting point Tm is measured by differential scanning calorimetry (DSC, Shinco DSC N-650) with a heating rate of 10°C / min.

[0095] Table 3:

[0096] Test Materials Td(℃) Tm(℃) Test Materials Td(℃) Tm(℃) 6 507.87 208.00 146 526.93 203.62 7 520.30 213.42 147 503.16 216.17 10 500.13 200.05 151 496.22 221.25 18 495.53 189.22 158 511.38 226.38 30 512.44 193.45 159 520.44 194.55 31 520.49 198.42 160 523.60 199.47 50 524.17 204.31 163 497.59 203.26 51 495.06 208.73 171 501.33 208.33 55 500.25 217.42 172 524.62 218.84 62 526.48 220.35 175 516.08 223.15 78 515.17 223.49 180 499.31 195.16 90 498.06 193.46 181 489.98 207.18 95 489.92 198.67 182 496.15 216.49 103 498.01 202.18 186 523.06 207.85 112 503.16 207.43 187 517.49 217.66 135 522.46 217.35

[0097] As can be seen from Table 3 above, the compounds of the present invention have relatively high Td and Tm values, indicating that they have excellent thermal stability. Applying them to organic electroluminescent devices can effectively extend the service life of the organic electroluminescent devices and obtain better use effects.

[0098] Device performance test:

[0099] Application Example 1:

[0100] ITO was used as the reflective layer anode substrate material, and its surface was treated with water, acetone, and N2 plasma in sequence;

[0101] On top of the ITO anode substrate, 10 nm of HT-1 doped with 5% by mass of NDP-9 was deposited to form a hole injection layer (HIL);

[0102] A hole transport layer (HTL) was formed by evaporating 60 nm of HT-1 on the hole injection layer (HIL);

[0103] EB-1 was vacuum evaporated on the hole transport layer (HTL) to form an electron blocking layer (EBL) with a thickness of 10 nm;

[0104] Compound 6 prepared in Example 1 of the present invention and G1 were co-evaporated as luminescent host materials in a mass ratio of 6:4, and GD-1 was evaporated as a doping material (the amount of GD-1 was 8% of the total weight of compound 6 and G1) on the electron blocking layer (EBL) to form a luminescent layer with a thickness of 30 nm;

[0105] HB-1 was evaporated onto the light-emitting layer to obtain a hole blocking layer (HBL) with a thickness of 20 nm;

[0106] ET-1 and LiQ were co-evaporated onto the hole blocking layer (HBL) in a mass ratio of 5:5 to obtain an electron transport layer (ETL) with a thickness of 50 nm;

[0107] Magnesium (Mg) and silver (Ag) were mixed and evaporated on the electron transport layer (ETL) in a mass ratio of 9:1 to form an electron injection layer (EIL) with a thickness of 50 nm;

[0108] Thereafter, silver (Ag) is evaporated onto the electron injection layer to form a cathode with a thickness of 100 nm, and a DNTPD with a thickness of 50 nm is deposited on the cathode sealing layer. In addition, the cathode surface is sealed with a UV curable adhesive and a sealing film (seal cap) containing a dehumidifier to protect the organic electroluminescent device from being affected by oxygen or moisture in the atmosphere. Thus, an organic electroluminescent device is prepared.

[0109]

[0110]

[0111] Application Example 2-31

[0112] Compounds 7, 10, 18, 30, 31, 50, 51, 55, 62, 78, 90, 95, 103, 112, 135, 146, 147, 151, 158, 159, 160, 163, 171, 172, 175, 180, 181, 182, 186, and 187 in Examples 2-31 of the present invention are used to replace compound 6 in Application Example 1, and other parts are consistent with Application Example 1, thereby preparing organic electroluminescent devices of Application Examples 2-31.

[0113] Comparative Example 1-2

[0114] The difference between Control Example 1-2 and Application Example 1 is that Compounds 1-19 and 1-322 in JP2012049518A are used to replace Compound 6 in Application Example 1, and the rest is the same as Application Example 1.

[0115] The organic electroluminescent devices prepared in Application Examples 1-31 and Comparative Examples 1 and 2 were tested respectively, and the test results are shown in Table 4.

[0116] Table 4

[0117]

[0118]

[0119] It can be seen from Table 4 above that the application of the compound of the present invention in an organic electroluminescent device as a main material of a light-emitting layer can improve the luminous efficiency of the organic electroluminescent device to a certain extent, reduce the starting voltage, and relatively reduce power consumption.

[0120] The organic electroluminescent devices prepared in the control examples 1-2 and the application examples 1-31 were tested for luminescence lifetime to obtain the luminescence lifetime T97% data (the time when the luminescence brightness decreases to 97% of the initial brightness). The test equipment was a TEO luminescent device lifetime test system. The results are shown in Table 5:

[0121] Table 5

[0122]

[0123] It can be seen from Table 5 above that when the compound of the present invention is used as the main material of the light-emitting layer and applied to an organic electroluminescent device, the service life of the prepared organic electroluminescent device is greatly improved, so it has a very broad application prospect.

Claims

1. A compound, characterized in that The compound is any one of the following compounds:

2. An organic electroluminescent device, characterized in that: It includes a first electrode, a second electrode and an organic layer formed between the first electrode and the second electrode; the organic layer includes a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer; the light-emitting layer contains the compound as claimed in claim 1.

3. The organic electroluminescent device according to claim 2, characterized in that: The light-emitting layer contains a light-emitting host material, and the light-emitting host material is a mixture of the compound of claim 1 and any one or more of compounds G1-G42. Compounds G1-G42 are as follows:

4. An electronic display device, characterized in that: Contains the organic electroluminescent device as claimed in claim 2.

5. An OLED lighting device, characterized in that: Contains the organic electroluminescent device as claimed in claim 2.

Images