Nitrogen-containing heterocyclic compound and organic electroluminescent device thereof

Abstract

The invention discloses a nitrogen-containing heterocyclic compound and an organic electroluminescent device thereof, which are characterized in that the nitrogen-containing heterocyclic compound is selected from a compound shown in a formula 1: # imgabs0 #, Ar1 and Ar2 are independently selected from substituted or unsubstituted C6 to C20 aryl groups and substituted or unsubstituted C2 to C24 heteroaryl groups, R1-R6 are independently selected from hydrogen, deuterium, fluorine and cyano groups, a, b, c and d are independently selected from integers from 0 to 3, and n is an integer from 0 to 3. E and f are respectively and independently selected from integers of 0-4, and Ar1, Ar2, (R1) a, (R2) b, (R3) c, (R4) d, (R5) e and (R6) f at least contain one deuterium. The other dibenzofuran is connected to the fourth site of the dibenzofuran connected with the triazine, and deuteration is performed, so that the molecular torque is enhanced, the chemical stability, thermal stability and photoelectric stability are improved, and the service life of a device is further prolonged; the organic light-emitting device according to an embodiment of the compound as a host material of a light-emitting layer exhibits significantly improved lifespan characteristics without lowering efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of organic electroluminescence, and specifically relates to a nitrogen-containing heterocyclic compound and an organic electroluminescent device. Background Art

[0002] An organic electroluminescent device (OLED) is a display technology that uses an electric field to excite a fluorescent material to emit light. Its working principle is that under the action of an electric field, holes injected from the positive electrode and electrons injected from the negative electrode recombine in the light-emitting layer to generate light. OLEDs have wide applications in fields such as mobile phones, tablet computers, TV displays, and lighting due to their advantages such as low-voltage startup, high brightness, wide viewing angle, fast response, and good temperature adaptability.

[0003] The composition structure of an organic electroluminescent device includes a cathode, an anode, and an organic layer disposed between the two. Currently, the organic layer structure of OLED devices used in the industry is usually a multi-layer structure, such as including a hole injection layer, a hole transport layer\electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and other film layers. For an OLED device including the above film layers, when a voltage is applied between the two electrodes, holes are injected from the anode into the organic layer, and electrons are injected from the cathode into the organic layer. When the holes and electrons meet, excitons are formed. When the excitons transfer energy to the doping material, light is emitted through the radiative transition of the doping material.

[0004] The progress of OLED technology not only depends on the innovation of device design and manufacturing processes, but more on the continuous research and development of organic light-emitting materials. Developing new high-performance organic light-emitting materials is of great significance for promoting the continuous development and application expansion of OLED technology.

[0005] The invention patent with the publication number 《CN116234805A》 discloses a heterocyclic compound, an organic light-emitting element including the same, and a composition of an organic layer of an organic light-emitting element. This patent discloses a compound with a triazine host, and a structure of bifuran and carbazole is provided on one of the side chains. Due to the poor compatibility between the green light hosts, the energy cannot be efficiently transferred to the doping material, resulting in a decrease in the efficiency of the conductor OLED device. Further, this patent also discloses a deuterated compound based on this structural formula. However, in the deuterated compound, the two dibenzofurans are connected between the 2nd position or the 3rd position. Its chemical stability, thermal stability, and photoelectric stability are poor, thereby affecting the lifespan of the device. The organic electroluminescent device of the embodiment with the above compound as the host material of the light-emitting layer shows significantly improved lifespan characteristics without reducing the efficiency. With the development of material research, there is a need to further develop on the basis of the above compound to obtain an organic electroluminescent compound with better performance. Summary of the Invention

[0006] The object of the present invention is to address the above technical problems. The present invention provides an organic electroluminescent compound and an organic electroluminescent device thereof, which are selected from the compounds represented by Formula 1:

[0007]

[0008] Wherein Ar1 and Ar2 are each independently selected from substituted or unsubstituted aryl groups having 6 to 20 carbon atoms or substituted or unsubstituted heteroaryl groups having 2 to 24 carbon atoms, and the substituents are selected from hydrogen, deuterium, C1-C10 alkyl groups, cyano groups or combinations thereof; R1-R6 are each independently selected from hydrogen, deuterium, fluorine, cyano groups; a, b, c, d are each independently integers from 0 to 3; e, f are each independently integers from 0 to 4; at least one of Ar1, Ar2, (R1)a, (R2)b, (R3)c, (R4)d, (R5)e, (R6)f contains deuterium.

[0009] As a preferred embodiment of the present invention, Ar1 and Ar2 are each independently selected from substituted or unsubstituted phenyl, biphenyl, naphthyl, phenanthryl, triphenylenyl, dibenzofuranyl, dibenzothiophenyl, and the substituents are selected from hydrogen, deuterium, C1-C10 alkyl groups, cyano groups or combinations thereof.

[0010] As a preferred embodiment of the present invention, Ar1 and Ar2 are each independently selected from phenyl and deuterated phenyl.

[0011] As a preferred embodiment of the present invention, it is selected from the compounds represented by Formula 2:

[0012]

[0013] Wherein D is deuterium and n is an integer from 1 to 30.

[0014] As a preferred embodiment of the present invention, it is selected from the compounds represented by Formula 2-1 to Formula 2-32:

[0015]

[0016]

[0017]

[0018] Wherein D is deuterium and n is an integer from 1 to 30.

[0019] As a preferred embodiment of the present invention, the nitrogen-containing heterocyclic compound is one of the compounds with the following structural formulas:

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031] An organic electroluminescent device includes a first electrode, a second electrode, and an organic layer formed between the first electrode and the second electrode, and the organic layer contains the nitrogen-containing heterocyclic compound of any one of the above.

[0032] As a preferred embodiment of the present invention, 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; at least one of the hole injection layer, the hole transport layer, the electron blocking layer, the light-emitting layer, the hole blocking layer, the electron transport layer, and the electron injection layer contains the nitrogen-containing heterocyclic compound of any one of the above.

[0033] As a preferred embodiment of the present invention, the light-emitting layer further contains at least one of Formula 3 or Formula 4 below:

[0034]

[0035] Wherein, Y1 and Y2 are each independently a single bond, a substituted or unsubstituted C6-C20 arylene group; A1 and A2 are each independently a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C2-C24 heteroaryl group; Ar3 to Ar16 are each independently hydrogen, deuterium, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C6-C20 aryl group, a substituted or unsubstituted C2-C24 heteroaryl group, a cyano group, or a combination thereof, and the substituents are hydrogen, deuterium, a C1-C10 alkyl group, a C6-C20 aryl group.

[0036] As a preferred embodiment of the present invention, the light-emitting layer contains a light-emitting host material, which is composed of one or more of the nitrogen-containing heterocyclic compounds described in any one of the above and compounds G1-G103, and the compounds G1-G103 are shown as follows:

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043] Advantages of the present invention:

[0044] 1. The N-type compound of the present invention provides a compound with a triazine host structure, with two difuran structures and carbazole arranged on one of its side chains, and further research on deuteration is carried out on this basis. Compared with the compound in which two dibenzofurans are connected at the 2nd or 3rd position and deuterated, in the present invention, another dibenzofuran is connected at the 4th position of the dibenzofuran connected to the triazine and deuterated, so as to enhance the molecular torque. Its chemical stability, thermal stability and optoelectronic stability are improved, thereby enhancing the lifespan of the device. The organic light-emitting device with the above compound as the host material of the light-emitting layer exhibits significantly improved lifespan characteristics without reducing efficiency.

[0045] 2. The N-type compound of the present invention can form a good Premix material with the P-type compound of the present invention, has good P / N stability and mass production stability during the evaporation process, and the formed Premix material has a more balanced carrier mobility, thereby greatly improving the efficiency and lifespan of the device.

[0046] 3. The N-type compound of the present invention has a high triplet energy level, effectively avoiding the reverse transfer of energy from the doped material to the host material, thereby improving the device efficiency and lifespan.

[0047] 4. The N-type compound of the present invention has good solubility, greatly reducing the material preparation cost and Mask cleaning cost. Description of the drawings

[0048] Figure 1 It is a schematic structural diagram of the organic electroluminescent device provided by the present invention;

[0049] The reference numerals in the figure respectively 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.

[0050] Figure 2 This is the HPLC spectrum of Compound 12 of the present invention.

[0051] Figure 3 This is the DSC spectrum of Compound 12 of the present invention. It can be seen from Figure 3 that the Tm value of Compound 12 is 263.84 °C.

[0052] Figure 4 This is the TGA spectrum of Compound 12 of the present invention. It can be seen from Figure 4 that the thermal weight loss temperature Td value of Compound 12 is 485.56 °C. Detailed Embodiments

[0053] The following further illustrate and describe 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 alternatives, modifications, and equivalents that may be included within the spirit and scope of the present disclosure as defined by the appended claims.

[0054] As used herein, in "deuterated" or "non - deuterated", the term "deuterated" means that at least one hydrogen in the group is re - coordinated with deuterium. The term "non - deuterated" means that all hydrogens in the group are not re - coordinated with deuterium.

[0055] The "aromatic group", "aryl" or "aromatic radical" herein refers to a group containing one or more aromatic rings, and the aromatic rings herein include, but are not limited to, benzene, naphthalene, phenanthrene, fluorene, acenaphthene, pyridine, pyrimidine, pyrrole, furan, thiophene, etc. C6 - C20 in the C6 - C20 aromatic group means that the group contains 6 - 20 carbon atoms. Aromatic groups can be divided into monocyclic aryl groups and polycyclic aryl groups. Specific aromatic groups in the present invention include, but are not limited to, phenyl, biphenyl, terphenyl, anthryl, naphthyl, phenanthryl, fluorenyl, dibenzofuranyl, dibenzothiophenyl, 9,9 - spirobifluorenyl, 9,9 - dimethylfluorenyl or 9,9 - diphenylfluorenyl, etc. Aromatic groups can be substituted and unsubstituted.

[0056] "Naphthenyl" as used herein refers to a monocyclic or fused ring (where "fused" rings mean that each ring in the system shares an adjacent pair of carbon atoms with other rings in the system) group consisting entirely of carbon atoms, where one or more of the rings are saturated alicyclic rings, which generally have 3 - 20 carbon atoms, preferably 3 - 12 carbon atoms, more preferably 3 - 10 carbon atoms. Naphthenyl can be divided into monocyclic alkyl groups having only one ring and polycyclic naphthenyl groups having multiple rings. Examples of monocyclic alkyl groups include, but are not limited to, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane. Naphthenyl can be substituted or unsubstituted.

[0057] "Cycloalkenyl" as used herein refers to a monocyclic or fused ring (where "fused" rings mean that each ring in the system shares an adjacent pair of carbon atoms with other rings in the system) group consisting entirely of carbon atoms, where one or more of the rings do not have a fully conjugated π - electron system and contain at least one alkenyl group, which generally have 3 - 20 carbon atoms, preferably 3 - 12 carbon atoms, more preferably 3 - 10 carbon atoms. Examples of cycloalkenyl include, but are not limited to, cyclopentene, cyclohexene, cyclohexadiene, cycloheptatriene. Cycloalkenyl can be substituted or unsubstituted.

[0058] "Deuterated aromatic group" as used herein refers to a group in which one or more hydrogen atoms in an aromatic group are replaced by deuterium.

[0059] "Deuterated phenyl" as used herein refers to a group in which one or more hydrogens in a phenyl group are replaced by deuterium.

[0060] "Heteroaryl" as used herein refers to a heteroaryl group obtained by replacing one or more C atoms in the structure of "aryl" with one or more heteroatoms (such as N, O, or S).

[0061] For those not specified with specific conditions in the examples, they are carried out under conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified with the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0062] Synthesis Example 1

[0063] Compound 12

[0064]

[0065] Compound 12 was prepared according to the following method:

[0066] Step S1:

[0067] Procedure: Under nitrogen protection, add raw materials (27.89 g, 0.076 mol, 1 eq) into the reaction flask, add bis(pinacolato)diboron (23.15 g, 0.0912 mol, 1.2 eq), add 300 ml of dioxane, then add potassium acetate (18.6 g, 0.19 mol, 2.5 eq), add the catalyst Pd2(dba)3 (0.69 g, 0.00076 mol, 1% eq), and ligand X-phos (0.72 g, 0.00152 mol, 2% eq). After adding all the materials, heat up to 105 °C and reflux for 4 h.

[0068] Workup: After the reaction solution is cooled, add it to water, separate the layers, pass the organic phase through silica gel and concentrate to dryness, then recrystallize once using the toluene-ethanol system. After drying, about 26.86 g of the product is obtained, and the yield is 77%.

[0069] Step S2:

[0070] Procedure: Under nitrogen protection, add intermediate 1 (23 g, 0.05 mol, 1 eq) and triazine raw material (21.65 g, 0.05 mol, 1 eq) into the reaction flask, add 500 ml of toluene, 120 ml of ethanol, potassium carbonate (17.25 g, 0.125 mol, 2.5 eq), 62.5 ml of water, palladium acetate (0.11 g, 0.0005 mol, 1%) and X-phos (0.476 g, 0.001 mol, 2% eq). After adding all the materials, heat up the reaction solution to reflux for 6 h, and sample for HPLC detection until the reaction is complete.

[0071] Workup: After the reaction solution is cooled, wash it with water, filter by suction, and dry the filter cake by blowing air. About 32.85 g of the product is obtained, and the yield is 90%.

[0072] Step S3:

[0073] Procedure: Add intermediate 2 (30 g, 0.041 mol, 1 eq) and deuterated benzene (138 g, 1.64 mol, 40 eq) into the reaction flask, add trifluoromethanesulfonic acid (30.75 g, 0.205 mol, 5 eq). After adding all the materials, heat up the reaction solution to 50 °C and react for 24 h.

[0074] Workup: After the reaction solution is cooled, add 50 g of heavy water and stir for 30 min, then filter by suction. Wash the filter cake with water and ethanol, dry it by blowing air at 85 °C, and then recrystallize and purify it using toluene. About 19.3 g of the product is obtained, and the yield is 52%.

[0075] Compounds 28, 48, 63, 76, 88, 100, 116, 123, 159, 200, 211, 227 are obtained in a similar method. See Table 1 below:

[0076] Table 1

[0077]

[0078]

[0079]

[0080] Synthesis Example 14

[0081] Compound 4

[0082]

[0083] Compound 4 was prepared according to the following method:

[0084] Step S1:

[0085] Step S2:

[0086] Yield: 53.4%.

[0087] Compounds 9, 24, 35, 60, 72, 84, 93, 95, 112, 131, 143, 144, 155, 171, 188, 191, 207, 223, 240 were obtained in a similar manner. See Table 2 below:

[0088] Table 2

[0089]

[0090]

[0091]

[0092]

[0093] The compounds prepared in the above Synthesis Examples 1 - 33 were subjected to synthetic identification, and the results are shown in Table 3 below:

[0094] Table 3

[0095]

[0096]

[0097] The above materials were subjected to basic performance tests, and the thermal decomposition temperature Td and glass transition temperature Tg were measured respectively. The test results are shown in Table 4 below.

[0098] Note: The thermal weight loss temperature Td is the temperature at which the weight loss mass ratio is 5% in a nitrogen atmosphere, and it is measured on a TGA N-1000 thermogravimetric analyzer. During the measurement, the nitrogen flow rate is 10 mL / min. The melting point Tm is measured by differential scanning calorimetry (DSC, Newkete DSC N-650), and the heating rate is 10 °C / min.

[0099] Table 4

[0100]

[0101]

[0102] According to the above data, it can be seen that the synthesized compounds of the present invention have excellent thermal stability, indicating that the compounds conforming to the general structural formula of the present invention all have excellent thermal stability and can meet the requirements for use as organic electroluminescent materials.

[0103] Device performance test:

[0104] Application Example 1:

[0105] ITO is used as the reflective layer anode substrate material, and its surface is treated with water, acetone, and N2 plasma in sequence;

[0106] Above the ITO anode substrate, 10 nm of HT-1 doped with 5% NDP-9 is deposited to form a hole injection layer (HIL);

[0107] Above the hole injection layer (HIL), 100 nm of HT-1 is evaporated to form a hole transport layer (HTL);

[0108] Above the hole transport layer (HTL), GP-1 is vacuum-evaporated to form an electron blocking layer (GPL) with a thickness of 10 nm;

[0109] Compound 12 prepared in Synthesis Example 1 of the present invention and G1 are co-evaporated in a ratio of 5:5 as the light-emitting host material, and GD-1 as the doping material (the dosage of GD-1 is 8% of the total weight of Compound 12 and G1) is evaporated on the electron blocking layer (GPL) to form a light-emitting layer with a thickness of 20 nm;

[0110] HB-1 is evaporated onto the light-emitting layer to obtain a hole blocking layer (HBL) with a thickness of 20 nm;

[0111] ET-1 and LiQ are co-evaporated in a ratio of 5:5 onto the hole blocking layer (HBL) to obtain an electron transport layer (ETL) with a thickness of 30 nm;

[0112] Magnesium (Mg) and silver (Ag) are mixed in a ratio of 9:1 and evaporated onto the electron transport layer (ETL) to form an electron injection layer (EIL) with a thickness of 50 nm;

[0113] Thereafter, silver (Ag) is evaporated onto the electron injection layer to form a cathode with a thickness of 100 nm. DNTPD with a thickness of 50 nm is deposited on the above cathode sealing layer. In addition, the cathode surface is sealed with a UV-curing adhesive and a packaging film (seal cap) containing a desiccant to protect the organic electroluminescent device from being affected by oxygen or moisture in the atmosphere. Thus, an organic electroluminescent device is prepared.

[0114]

[0115] Application Example 2-33

[0116] Compounds 28, 48, 63, 76, 88, 100, 116, 123, 159, 200, 211, 227, 4, 9, 24, 35, 60, 72, 84, 93, 95, 112, 131, 143, 144, 155, 171, 188, 191, 207, 223, 240 in Synthesis Example 2-33 of the present invention are used as the green light host material for co-evaporation respectively, and the other parts are the same as those in Application Example 1. Thus, the organic electroluminescent devices of Application Example 2-33 are fabricated.

[0117] Comparative Example 1-5:

[0118] The difference from Application Example 1 is that Compounds 1-63, 1-127, 1-191, 1-273, 1-274 are used to replace Compound 12 in Application Example 1 as the green light host material for co-evaporation respectively, and the rest is the same as that in Application Example 1.

[0119] The characteristics of the organic electroluminescent devices fabricated in the above Application Examples and the organic electroluminescent devices fabricated in the Comparative Examples are measured under the condition of a current density of 10 mA / cm2, and the results are shown in Table 5 below.

[0120] Table 5

[0121]

[0122]

[0123] As can be seen from Table 5 above, when the compounds of the present invention are applied to organic electroluminescent devices, at the same current density, the luminous efficiency is greatly improved, the turn-on voltage of the device decreases, and the power consumption of the device is relatively reduced.

[0124] The organic electroluminescent devices prepared in Comparative Examples 1-5 and Application Examples 1-13 were respectively subjected to a luminescence lifetime test to obtain the luminescence lifetime T97% data (the time when the luminescence brightness decreased to 97% of the initial brightness), and the test equipment was a TEO luminescent device lifetime test system. The results are shown in Table 6 as follows:

[0125] Table 6:

[0126]

[0127]

[0128] As can be seen from Table 6 above, when the compound of the present invention is applied to an organic electroluminescent device, the service life is greatly improved under the same current density, and it has broad application prospects.

[0129] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A nitrogen-containing heterocyclic compound, characterized in that Selected from the compounds shown in formula 1: Wherein, Ar1 and Ar2 are each independently selected from substituted or unsubstituted C6 to C20 aryl groups, substituted or unsubstituted C2 to C24 heteroaryl groups, the substituents are selected from hydrogen, deuterium, C1 to C10 alkyl groups, cyano groups or combinations thereof, R1-R6 are each independently selected from hydrogen, deuterium, fluorine, cyano groups, a, b, c, d are each independently selected from integers of 0-3, e, f are each independently selected from integers of 0-4, and at least one deuterium is contained in Ar1, Ar2, (R1)a, (R2)b, (R3)c, (R4)d, (R5)e and (R6)f.

2. A nitrogen-containing heterocyclic compound according to claim 1, characterized in that: Ar1 and Ar2 are each independently selected from substituted or unsubstituted phenyl, biphenyl, naphthyl, phenanthryl, triphenylene, dibenzofuranyl, dibenzothiophenyl, and the substituent is selected from hydrogen, deuterium, C1 to C10 alkyl, cyano or a combination thereof.

3. A nitrogen-containing heterocyclic compound according to claim 1, characterized in that: Ar1 and Ar2 are each independently selected from phenyl and deuterated phenyl.

4. A nitrogen-containing heterocyclic compound according to claim 1, characterized in that: Selected from the compounds shown in formula 2: Wherein, D is deuterium, and n is an integer from 1 to 30.

5. A nitrogen-containing heterocyclic compound according to claim 1, characterized in that: Selected from compounds represented by formula 2-1 to formula 2-32: Wherein D is deuterium, and n is an integer from 1 to 30.

6. A nitrogen-containing heterocyclic compound according to claim 1, characterized in that: The nitrogen-containing heterocyclic compound is one of the following structural compounds:

7. An organic electroluminescent device, characterized in that: The invention 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 nitrogen-containing heterocyclic compound according to any one of claims 1 to 6.

8. The organic electroluminescent device according to claim 7, characterized in that: 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; at least one of the hole injection layer, the hole transport layer, the electron blocking layer, the light-emitting layer, the hole blocking layer, the electron transport layer, and the electron injection layer contains a nitrogen-containing heterocyclic compound as described in any one of claims 1 to 6.

9. The organic electroluminescent device according to claim 8, characterized in that: The light-emitting layer further contains at least one of the following formula 3 or formula 4: wherein Y1 and Y2 are each independently a single bond, a substituted or unsubstituted C6 to C20 arylene group; A1 and A2 are each independently a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C2 to C24 heteroaryl group; Ar3 to Ar16 are each independently hydrogen, deuterium, a substituted or unsubstituted C1 to C10 alkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C2 to C24 heteroaryl group, a cyano group or a combination thereof, and the substituents are hydrogen, deuterium, a substituted or unsubstituted C1 to C10 alkyl group, a C6 to C20 aryl group.

10. The organic electroluminescent device according to claim 9, characterized in that: The light-emitting layer contains a light-emitting host material, and the light-emitting host material is a mixture of the nitrogen-containing heterocyclic compound according to any one of claims 1 to 6 and one or more of compounds G1 to G103, and the compounds G1 to G103 are as follows:

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