CN113527268A

CN113527268A - Compound containing biscarbazole and triazine structure and organic electroluminescent device

Info

Publication number: CN113527268A
Application number: CN202110950612.7A
Authority: CN
Inventors: 钱超; 许军; 朱东林; 黄明辉
Original assignee: Nanjing Topto Materials Co Ltd
Current assignee: Nanjing Topto Materials Co Ltd
Priority date: 2021-08-18
Filing date: 2021-08-18
Publication date: 2021-10-22
Anticipated expiration: 2041-08-18
Also published as: CN113527268B

Abstract

The invention discloses a compound containing a biscarbazole and triazine structure and an organic electroluminescent device, and relates to the technical field of organic electroluminescence. The compound containing the biscarbazole and the triazine structure has a structure shown in a formula (I). The compound introduces deuteration on biphenyl group among carbazole, carbazole and triazine structure, can well adjust HOMO energy level of material molecule, makes matching between the compound and adjacent functional layer better, and deuteration on carbazole can further improve triplet state energy level of material molecule, thereby effectively improving luminous efficiency and service life of device.

Description

Compound containing biscarbazole and triazine structure and organic electroluminescent device

Technical Field

The invention relates to the technical field of organic electroluminescence, in particular to a compound containing a biscarbazole and triazine structure and an organic electroluminescent device.

Background

Organic electroluminescent devices (OLEDs) have been a focus of research in the field of flat panel displays internationally in recent years. Compared with the LCD, the LCD has the following advantages:

the organic plastic layer of the OLED is thinner, lighter, and more flexible than the crystal layer of the LED (light emitting diode) or LCD (liquid crystal display);

the light-emitting layer of the OLED is light, so that the base layer can be made of a material with high flexibility instead of a rigid material, the OLED base layer is made of a plastic material, and the LED and the LCD are made of a glass base layer;

the OLED is a current-type organic light emitting device, and emits light by injection and recombination of carriers, and the intensity of light emission is proportional to the injected current. Under the action of an electric field, holes generated by an anode and electrons generated by a cathode move, are respectively injected into a hole transport layer and an electron transport layer, and migrate to a light emitting layer. When the two meet at the light emitting layer, energy excitons are generated, thereby exciting the light emitting molecules to finally generate visible light.

As a next-generation flat panel display technology, Organic light-emitting diodes (OLEDs) have advantages of active light emission, low driving voltage, fast response speed, wide viewing angle, thin and light device, and flexible display, and have recently received wide attention from academia and industry. If the full-color display of the OLED is to be realized, red, green and blue three-primary-color light-emitting materials are indispensable. Among them, a blue light material is particularly important, which can provide not only necessary blue emission light but also green and red light by energy transfer. Moreover, the blue light material is also the key to effectively reduce the energy consumption of the full-color OLED. However, since the energy gap of the blue light material is wide, the energy level matching between the electron orbital level and the carrier injection/transmission material is poor, and the working stability of the material is reduced by the high excited state energy level, so that the development of a high-performance blue light material luminescent device is very difficult. At present, the research on red light and green light materials is mature, the performance of devices of the red light and green light materials reaches the level of practical application, the performance of blue light OLEDs still needs to be further improved, and factors which have large influence on the performance of the blue light OLEDs are more, wherein the doped materials are hot spots of the current research.

Currently, organic electroluminescent devices are generally constructed with an anode, a cathode, and an organic layer between the two electrodes. The organic layer may be composed of a Hole Injection Layer (HIL), an Electron Injection Layer (EIL), a Hole Transport Layer (HTL), an Electron Transport Layer (ETL), an Electron Blocking Layer (EBL), a Hole Blocking Layer (HBL), an emission layer (EML), and the like. Wherein the material of the light emitting layer is the most important factor for determining the light emitting efficiency, lifetime and performance of the device. The luminescent layer material comprises a main material and a doping material, and the main material in the luminescent layer is mostly monopolized by foreign enterprises at present, so that the research and development of the main material is independent, and the monopolization of the material is broken to become a research hotspot of colleges and universities of various enterprises.

Disclosure of Invention

The invention aims to provide a compound containing a biscarbazole and triazine structure, which has excellent organic electroluminescent efficiency and long-term luminescent life.

Another object of the present invention is to provide an organic electroluminescent device.

The technical scheme of the invention is as follows:

a compound containing biscarbazole and triazine structure with a structure shown as a formula (I),

wherein,

R₁～R₈each independently is hydrogen, deuterium, phenyl or deuterated phenyl;

R₉～R₁₀、R₁₆～R₁₈each independently is hydrogen, deuterium or a single bond to a substituted or substituted carbazole group;

R₁₁～R₁₅each independently is hydrogen, deuterium or a single bond to a triazine group;

R₁₉～R₂₆each independently is hydrogen, deuterium, phenyl or deuterated benzeneA group;

and R is₁～R₂₆The amount of deuterium contained in the alloy is 4-8.

In a preferred embodiment, R₁～R₂₆The number of deuterium substituents is 4-8.

In another preferred embodiment, R₁～R₂₆4-8 of them are deuterium substituents.

In another preferred embodiment, R₁～R₄Each independently is deuterium, or R₅～R₈Each independently is deuterium, or R₁₁～R₁₅Four of (a) are each independently deuterium, or R₉～R₁₀And R₁₆～R₁₈Four of (a) are each independently deuterium, or R₁₉～R₂₂Each independently is deuterium, or R₂₃～R₂₆Independently from each other, is deuterium.

In a preferred embodiment, R₁～R₈Each independently is hydrogen, deuterium or phenyl.

In a preferred embodiment, R₁₉～R₂₆Each independently is hydrogen, deuterium or phenyl.

In a preferred embodiment, R₉～R₁₈The biphenylene group is selected from:

wherein, a₁Is a linking moiety to a triazine group of formula (I)₂Is a linking moiety to a carbazole group of formula (I).

Further, the biscarbazole-and-triazine-containing compound having the structure represented by formula (I) in the present application may be selected from the following compounds:

the compound containing the biscarbazole and triazine structure with the structure of the formula (I) can be synthesized according to the following route.

Wherein each group is as defined above.

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 a compound with a biscarbazole and triazine structure.

Further, the organic layer includes a hole injection layer, a first hole transport layer, a second hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer; wherein at least one of the hole injection layer, the first hole transport layer, the second hole transport layer, the light-emitting layer, the hole blocking layer, the electron transport layer and the electron injection layer contains a compound having a biscarbazole and triazine structure.

Further, the light-emitting layer contains a compound having a biscarbazole structure and a triazine structure according to the present invention.

Further, the light-emitting layer further contains at least one compound of the following formulae G1 to G56:

the invention also discloses an electronic display device containing the organic electroluminescent device.

The invention also discloses an OLED lighting device containing the organic electroluminescent device.

Unless otherwise indicated, the following terms used in the claims and specification have the following meanings.

"Hydrogen" means protium (1H), which is the predominant stable isotope of hydrogen.

"deuterium", which is a stable isotope of hydrogen, also known as deuterium, has the elemental symbol D.

"deuterated phenyl" means that at least one hydrogen atom on the phenyl group is replaced by a deuterium atom, which can be mono-deuterated phenyl, di-deuterated phenyl, tri-deuterated phenyl, tetra-deuterated phenyl, penta-deuterated phenyl. Specific examples thereof include 2-deuterated phenyl, 3-deuterated phenyl, 4-deuterated phenyl, 2,4,5, 6-tetradeuterated phenyl, and 2,3,4,5, 6-pentadeuterated phenyl.

The room temperature of the invention is 25 +/-5 ℃.

The invention has the beneficial effects that:

the invention designs a compound used as an organic electroluminescent material, which has the following characteristics:

firstly, deuterated compounds are introduced into biphenyl groups among carbazole, carbazole and triazine structures, and because electron clouds determining HOMO energy level in material molecules are mainly distributed on carbazole, introduction of deuterated compounds into carbazole can well adjust HOMO energy level of material molecules, so that matching between itself and adjacent functional layers is better, and meanwhile, deuterated compounds on carbazole can further improve triplet state energy level of material molecules, thereby effectively improving luminous efficiency and service life of devices. Deuteration is introduced to biphenyl group between carbazole and triazine, so that steric hindrance of material molecules is further increased, and large pi conjugate effect between donor and acceptor is effectively interrupted, thereby effectively improving triplet state energy level of the material molecules. Therefore, deuteration on biphenyl group between carbazole, carbazole and triazine has higher triplet state energy level and better device performance than deuteration on other functional group.

Secondly, the compound designed by the invention has high selectivity to the quantity and the site of the deuterated group, and we find that when deuterium is in a certain quantity and characteristic site, the luminous efficiency and the service life of the material can be greatly improved, otherwise, the performance of the material is similar to that of the non-deuterated compound.

Thirdly, the compound has two carbazole structures, and the carbazole group has higher triplet state energy level, so that the compound also has higher triplet state energy level, and the characteristic effectively avoids the reverse transfer of energy from the doped material to the main material, thereby further improving the luminous efficiency of the device; meanwhile, deuteration can effectively increase the thermal stability and chemical stability of material molecules and reduce the probability of vibration and non-radiative transition in the material molecules, thereby prolonging the service life and improving the efficiency of the device.

The organic electroluminescent device prepared by using the compound designed by the invention has better luminous efficiency and service life.

Drawings

Fig. 1 is a schematic view of the structure of an organic electroluminescent device of the present invention.

The reference numbers in the figures represent respectively: 1-anode, 2-hole injection layer, 3-first hole transport layer, 4-second hole transport layer, 5-luminescent layer, 6-hole barrier layer, 7-electron transport layer, 8-electron injection layer and 9-cathode.

FIG. 2 is an HPLC chart of Compound 2 prepared in example 2 of the present invention.

FIG. 3 is a DSC of Compound 2 prepared in example 2 of the present invention, and it can be seen from FIG. 3 that the Tg value of Compound 2 is 146.33 ℃.

Fig. 4 is a TGA diagram of compound 2 prepared in example 2 of the present invention, and it can be seen from fig. 4 that the thermal weight loss temperature Td value is 508.80 ℃.

FIG. 5 is a graph showing the life of organic electroluminescent devices in application example 2 and comparative example 4 of the present invention; as can be seen from fig. 5, T97% lifetimes of the organic electroluminescent devices prepared in application example 2 and comparative example 4 of the present invention were 618h and 439h, respectively.

Detailed Description

Embodiments of the various aspects are further illustrated and described below. It should be understood that the description herein is not intended to limit the claims to the particular aspects described. On the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the disclosure as defined by the appended claims.

As used herein, in "substituted" or "unsubstituted," the term "substituted" means that at least one hydrogen in the group is re-coordinated to a hydrocarbyl group, a hydrocarbon derivative group, a halogen, or a cyano (-CN). The term "unsubstituted" means that at least one hydrogen in the group does not re-coordinate with the hydrocarbyl, hydrocarbon derivative group, halogen, or cyano (-CN). Examples of the hydrocarbon group or hydrocarbon derivative group may include C1 to C20 alkyl groups, C2 to C20 alkenyl groups, C2 to C20 alkynyl groups, C6 to C20 aryl groups, C5 to C20 heteroaryl groups, C1 to C20 alkylamino groups, C6 to C20 arylamino groups, C6 to C20 heteroarylamino groups, C6 to C20 arylheteroarylamino groups, and the like, but are not limited thereto.

The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Example 1:

the synthesis of compound 1 is as follows:

under the protection of nitrogen, compound 1-a (1.1eq, 13.85g, 449.38g/mol, 30.83mmol), compound 1-b (1eq, 10g, 356.81g/mol, 28.03mmol) were dissolved in 200mL of toluene, palladium acetate (0.31g, 224.51g/mol, 1.40mmol), X-phos (0.67g, 476.72g/mol, 1.40mmol), potassium carbonate (11.62g, 138.21g/mol, 84.08mmol) were added, 100mL of ethanol and 50mL of water were added, the reaction was stirred overnight at 82 ℃, and the progress of the reaction was monitored by HPLC.

After HPLC monitoring compound 1-b completely reacts, the reaction is stopped, the reaction solution is cooled to room temperature, 60mL of water is added, stirring is carried out for 20min, suction filtration is carried out to obtain a filter cake, the filter cake is rinsed for 2 times by using water and ethanol and then dried for 6 hours at 80 ℃ in vacuum, the dried filter cake is added into a 250mL three-neck flask, 100mL of o-dichlorobenzene is added, the solid is completely dissolved when the filter cake is heated to 120 ℃, the filter cake is filtered through silica gel and an activated carbon funnel when the filter cake is completely dissolved, the filtrate is naturally cooled to room temperature, after white solid is separated out, suction filtration is carried out to obtain a filter cake, and the filter cake is recrystallized twice to obtain a final target product compound 1(10.09g, 15.67mmol, yield 55.9%), ESI-MS (M/z) (M +): theoretical 643.77, found 643.52, elemental analysis result (molecular formula C45H25D4N 5): theoretical value C, 83.96; h, 5.17; n, 10.88; found C, 83.93; h, 5.12; and N, 10.95.

Example 2:

the synthesis of compound 2 is as follows:

the preparation method is basically the same as that of example 1, and the final target product, compound 2, is obtained with the yield of 52.6%, ESI-MS (M/z) (M +): theoretical 643.77, found 643.25, elemental analysis result (molecular formula C45H25D4N 5): theoretical value C, 83.96; h, 5.17; n, 10.88; found C, 83.93; h, 5.15; n, 10.92.

Example 3:

the synthesis of compound 13 is as follows:

the preparation was carried out in essentially the same manner as in example 1, giving the final desired product, Compound 13, in 48.3% yield, ESI-MS (M/z) (M +): theoretical 643.77, found 643.15, elemental analysis result (molecular formula C45H25D4N 5): theoretical value C, 83.96; h, 5.17; n, 10.88; found C, 83.99; h, 5.20; n, 10.81.

Example 4:

the synthesis of compound 26 is as follows:

the preparation method is basically the same as that of example 1, and the final target compound 26 is obtained with the yield of 45.8%, ESI-MS (M/z) (M +): theoretical 647.79, found 647.38, elemental analysis result (molecular formula C45H21D8N 5): theoretical value C, 83.43; h, 5.75; n, 10.81; found C, 83.45; h, 5.77; n, 10.78.

Example 5:

the synthesis of compound 40 was as follows:

the preparation was carried out in essentially the same manner as in example 1, giving the final desired compound 40 in 54.7% yield, ESI-MS (M/z) (M +): theoretical 643.77, found 643.82, elemental analysis result (molecular formula C45H25D4N 5): theoretical value C, 83.96; h, 5.17; n, 10.88; found C, 83.91; h, 5.19; n, 10.90.

Example 6:

the synthesis of compound 47 is as follows:

the preparation was carried out in essentially the same manner as in example 1, giving the final desired compound 47 in 46.4% yield, ESI-MS (M/z) (M +): theoretical 643.77, found 643.19, elemental analysis result (molecular formula C45H25D4N 5): theoretical value C, 83.96; h, 5.17; n, 10.88; found C, 83.87; h, 5.22; n, 10.91.

Example 7:

the synthesis of compound 57 is as follows:

the preparation was carried out in essentially the same manner as in example 1, giving the final desired compound 57 in 48.2% yield, ESI-MS (M/z) (M +): theoretical 647.79, found 647.33, elemental analysis result (molecular formula C45H21D8N 5): theoretical value C, 83.43; h, 5.75; n, 10.81; found C, 83.47; h, 5.79; n, 10.74.

Example 8:

the synthesis of compound 62 is as follows:

the preparation was carried out in essentially the same manner as in example 1, giving the final desired compound 62 in 43.9% yield, ESI-MS (M/z) (M +): theoretical 719.87, found 719.56, elemental analysis result (molecular formula C51H29D4N 5): theoretical value C, 85.09; h, 5.18; n, 9.73; found C, 85.02; h, 5.24; n, 9.74.

Example 9:

the synthesis of compound 92 was as follows:

the preparation was carried out in essentially the same manner as in example 1, giving the final desired compound 92 in 42.8% yield, ESI-MS (M/z) (M +): theoretical 719.87, found 719.55, elemental analysis result (molecular formula C51H29D4N 5): theoretical value C, 85.09; h, 5.18; n, 9.73; found C, 85.04; h, 5.23; n, 9.73.

Example 10:

the synthesis of compound 98 is as follows:

the preparation was carried out in essentially the same manner as in example 1, giving the final desired compound 98 in 46.2% yield, ESI-MS (M/z) (M +): theoretical 719.87, found 719.48, elemental analysis result (molecular formula C51H29D4N 5): theoretical value C, 85.09; h, 5.18; n, 9.73; found C, 85.14; h, 5.12; n, 9.74.

Example 11:

the synthesis of compound 128 is as follows:

the preparation method is basically the same as that of example 1, and the final target compound 128 is obtained with 47.1% of yield, ESI-MS (M/z) (M +): theoretical 719.87, found 719.68, elemental analysis result (molecular formula C51H29D4N 5): theoretical value C, 85.09; h, 5.18; n, 9.73; found C, 85.17; h, 5.10; n, 9.73.

Example 12:

the synthesis of compound 133 was as follows:

the preparation was carried out in essentially the same manner as in example 1, giving the final desired compound 133 in 44.8% yield, ESI-MS (M/z) (M +): theoretical 719.87, found 719.95, elemental analysis result (molecular formula C51H29D4N 5): theoretical value C, 85.09; h, 5.18; n, 9.73; found C, 85.05; h, 5.12; and N, 9.83.

Example 13:

the synthesis of compound 174 was as follows:

the preparation was carried out in essentially the same manner as in example 1, giving the final desired product, compound 174, in 42.5% yield, ESI-MS (M/z) (M +): theoretical 719.87, found 719.08, elemental analysis result (molecular formula C51H29D4N 5): theoretical value C, 85.09; h, 5.18; n, 9.73; found C, 85.06; h, 5.16; n, 9.78.

And (3) testing the material properties:

compounds

1, 2, 13, 26, 40, 47, 57, 62, 92, 98, 128, 133, 174 according to the invention were tested for a thermal weight loss temperature Td and a glass transition temperature Tg, the results of which are shown in table 1 below.

Note: the thermogravimetric analysis was carried out on a TGAN-1000 thermogravimetric analyzer at a temperature Td of 5% weight loss in a nitrogen atmosphere, the nitrogen flow rate was 10mL/min, the glass transition temperature Tg was measured by differential scanning calorimetry (DSC, New Zedoku DSC N-650), and the temperature rise rate was 10 ℃/min.

Table 1:

item	Material	Td/℃	Tg/℃
				Example 01	1	501.26	143.26
Example 02	2	508.80	146.33
				Example 03	13	512.61	150.19
Example 04	26	499.55	162.45
				Example 05	40	515.68	135.67
Example 06	47	507.14	157.48
				Example 07	57	495.19	132.91
Example 08	62	490.28	140.42
				Example 09	92	504.48	130.17
Example 10	98	520.56	159.54
				Example 11	128	489.77	163.18
Example 12	133	493.35	156.22
				Example 13	174	513.51	168.06

From the data, the compound synthesized by the invention has excellent thermal stability, which indicates that the compounds according to the structural general formula of the invention have excellent thermal stability and can meet the use requirements of organic electroluminescent materials.

Testing the performance of the device:

application example 1:

adopting ITO as the anode substrate material of the reflecting layer, and sequentially using water, acetone and N₂Carrying out surface treatment on the glass substrate by plasma;

depositing 10nm of HT-1 doped with 5% (mass percent) HAT-CN on the ITO anode substrate to form a Hole Injection Layer (HIL);

evaporating HT-1 with the thickness of 100nm above the Hole Injection Layer (HIL) to form a first Hole Transport Layer (HTL);

vacuum evaporating GP above the first Hole Transport Layer (HTL) to form a second hole transport layer (GPL) with the thickness of 30 nm;

carrying out co-evaporation on the compound 1 and G1 designed by the invention as green host materials according to the mass ratio of 5:5, and carrying out evaporation on GD-1 as a doping material (the using amount of GD-1 is 8% of the total mass of the compound 1 and G1) on a second hole transport layer (GPL) to form a luminescent layer with the thickness of 30 nm;

evaporating HB-1 onto the light-emitting layer to obtain a Hole Blocking Layer (HBL) with the thickness of 20 nm;

performing co-evaporation on ET-1 and LiQ to obtain an Electron Transport Layer (ETL) with the thickness of 30nm on a Hole Blocking Layer (HBL) according to the mass ratio of 5: 5;

mixing magnesium (Mg) and silver (Ag) in a mass ratio of 9:1, and evaporating the mixture above an Electron Transport Layer (ETL) to form an Electron Injection Layer (EIL) with the thickness of 50 nm;

thereafter, silver (Ag) was evaporated over the electron injection layer to form a cathode having a thickness of 100nm, DNTPD having a thickness of 50nm was deposited on the above-mentioned cathode sealing layer, and further, the surface of the cathode was sealed with a UV hardening adhesive and a sealing film (seal cap) containing a moisture scavenger to protect the organic electroluminescent device from oxygen or moisture in the atmosphere, thereby preparing an organic electroluminescent device.

Application examples 2 to 13

Organic electroluminescent devices of application examples 2 to 13 were produced by using compounds 2, 13, 26, 40, 47, 57, 62, 92, 98, 128, 133 and 174 in examples 2 to 13 of the present invention as green host materials, respectively, and the rest of the materials were the same as in application example 1.

Comparative examples 1 to 6:

the difference from application example 1 is that compound 1 was replaced with deuterated compounds A-1-D of A-1, A-3, A-4, A-5, A-11 and A-1 of WO2020130381A1, respectively, as green host materials, and the rest was the same as application example 1.

The characteristics of the organic electroluminescent element manufactured in the above application example and the organic electroluminescent element manufactured in the comparative example were that the current density was 10mA/cm²The results of measurements under the conditions of (1) are shown in Table 2.

Table 2:

as can be seen from the above Table 2, when the compound of the present invention is applied to an organic electroluminescent device, the luminous efficiency is greatly improved under the same current density, the start voltage of the device is reduced, the power consumption of the device is relatively reduced, and the service life of the device is correspondingly improved.

The organic electroluminescent devices prepared in comparative examples 1 to 6 and application examples 1 to 13 were subjected to a light emission life test to obtain light emission life T97% data (time for which light emission luminance was reduced to 97% of initial luminance), and the test apparatus was a TEO light emitting device life test system. The results are shown in Table 3:

table 3:

as can be seen from Table 3, the compound of the present invention has a greatly improved service life and a broad application prospect when applied to an organic electroluminescent device under the same current density.

Claims

1. A compound containing biscarbazole and triazine structure with a structure shown as a formula (I),

wherein,

R₉～R₁₀、R₁₆～R₁₈each independently is hydrogen, deuterium, or a single bond to the N of a substituted or unsubstituted carbazole group;

R₁₉～R₂₆each independently is hydrogen, deuterium, phenyl or deuterated phenyl;

and R is₁～R₂₆The amount of deuterium contained in the alloy is 4-8.

2. The compound of claim 1, wherein R₁～R₂₆The number of deuterium substituents is 4-8.

3. The compound of claim 1, wherein R₁～R₈Each independently is hydrogen, deuterium or phenyl.

4. The compound of claim 1, wherein R₁₉～R₂₆Each independently is hydrogen, deuterium or phenyl.

5. The compound of claim 1, wherein R₉～R₁₈The biphenylene group is selected from:

6. The compound of claim 1, wherein the compound is selected from the group consisting of:

7. an organic electroluminescent device comprising a first electrode, a second electrode, and an organic layer formed between the first electrode and the second electrode, the organic layer containing the compound according to any one of claims 1 to 6; in particular, the organic layer comprises a hole injection layer, a first hole transport layer, a second hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer and an electron injection layer; at least one of the hole injection layer, the first hole transport layer, the second hole transport layer, the light-emitting layer, the hole blocking layer, the electron transport layer, and the electron injection layer contains the compound according to any one of claims 1 to 6, and particularly the light-emitting layer contains the compound according to any one of claims 1 to 6.

8. The organic electroluminescent device according to claim 7, wherein the light-emitting layer further contains at least one of the following compounds G1-G56:

9. an electronic display device comprising the organic electroluminescent element according to claim 7.

10. An OLED lighting device comprising the organic electroluminescent element according to claim 7.