Organic electroluminescent compounds, organic electroluminescent devices and display equipment

Abstract

This invention discloses an organic electroluminescent compound, an organic electroluminescent device, and a display device. The compound has a structure as shown in formula (1). By introducing deuterium, this invention endows the compound with good chemical stability, thermal stability, and photoelectric stability. Since the deuterium is introduced primarily at active sites with high electron cloud density, compared to compounds with high deuteration rates, this invention improves material and device performance through deuteration while also offering good economic benefits. Furthermore, this invention represents a further optimization of existing compounds. Compared to compounds with relatively similar structures and performance characteristics in devices, this invention, while achieving technical effects no less than existing technologies, further reduces the molecular weight of the compound, significantly lowering the sublimation / evaporation temperature. In production practice, this has a positive impact on maintaining production line stability and improving product yield, playing a positive role.

Description

Technical Field

[0001] This invention belongs to the field of organic electroluminescence technology, specifically relating to an organic electroluminescent compound, an organic electroluminescent device, and a display device. Background Technology

[0002] OLED (Organic Light-Emitting Diode) is a device that uses multiple layers of organic thin films to generate electroluminescence. It requires a low driving voltage, which makes OLED stand out in display applications.

[0003] Evaporation is one of the key manufacturing processes for OLEDs. In an evaporation machine, an organic evaporation source is heated in a vacuum environment, transforming the material from a solid to a gaseous phase. This gaseous material then sublimates and deposits onto a substrate, ultimately forming an organic thin film. Temperature setting is one of the most critical parameters in the organic evaporation process, typically determined by the sublimation temperature of the organic material. Temperature control directly affects the sublimation behavior and film quality. However, if the required evaporation temperature is too high, it can have various negative impacts on the equipment and the final product. For example, carbides or non-volatile residues produced by material decomposition at high temperatures can contaminate the vacuum system cavity, increasing equipment maintenance frequency. High-temperature radiation can cause thermal expansion of the metal mask, leading to pattern misalignment and pixel shift in the device.

[0004] Therefore, designing suitable compounds to reduce the sublimation and evaporation temperatures of materials while maintaining device performance is of great significance for the production and manufacturing of materials and devices. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of this invention is to further optimize organic electroluminescent compounds based on the prior art.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0007] An organic electroluminescent compound, characterized in that it is selected from compounds as shown in formula (1):

[0008]

[0009] In formula (1):

[0010] R0, R1, R2 and R3 are each independently selected from hydrogen or deuterium, and at least two of them are deuterium;

[0011] R4 is methyl or deuterated methyl, and t is 0 or 1;

[0012] Ar is a C6-C12 aryl group that is substituted with or unsubstituted with methyl or deuterated methyl groups.

[0013] Preferably, Ar is selected from biphenyls that are substituted with or unsubstituted with methyl or deuterated methyl groups.

[0014] Preferably, the compound is selected from compounds shown in formula (1-1):

[0015]

[0016] In equation (1-1):

[0017] R0, R1, R2 and R3 are each independently selected from hydrogen or deuterium, and at least two of them are deuterium;

[0018] R4, R5, and R6 are each independently selected from methyl or deuterated methyl groups, t, m, and n are each independently represented by 0 or 1, and t+m+n≤1.

[0019] Preferably, in R0-R3, at least R0 and R2 are deuterium, and R1 and R3 are each independently deuterium or hydrogen. Further, in R0-R3, R0, R2 and R3 are deuterium, and R1 is deuterium or hydrogen.

[0020] Preferably, formula (1) is selected from compounds shown in formulas (1-2) or (1-3):

[0021]

[0022] in:

[0023] R0, R1, R2 and R3 are each independently selected from hydrogen or deuterium, and at least two of them are deuterium;

[0024] R4, R5, and R6 are each independently selected from methyl or deuterated methyl groups, m and n are each independently represented by 0 or 1, and m+n≤1.

[0025] Preferably, the compounds of the present invention are selected from any one of the following compounds:

[0026] .

[0027] In the above general formulas or specific compounds, D represents deuterium, and CD3 or D3C represents a methyl group substituted with three deuterium groups.

[0028] An organic electroluminescent device, characterized in that it comprises an anode, a cathode, and an organic layer formed between the anode and the cathode, said organic layer comprising an organic electroluminescent compound as described in any of the preceding claims.

[0029] Furthermore, 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 sequentially formed between the anode and the cathode, wherein the second hole transport layer is made of a compound as described in any of the preceding claims.

[0030] A display device, characterized in that it comprises the organic electroluminescent device described in any of the preceding claims. Beneficial effects

[0031] 1) The compounds of the present invention, through the introduction of deuterium, have good chemical stability, thermal stability and photoelectric stability, as well as good carrier mobility, which broadens the exciton recombination region and can improve the performance of the device in terms of luminous efficiency and luminous lifetime.

[0032] 2) In the compounds of this invention, since the deuterium is introduced mainly at the active sites with high electron cloud density, compared with compounds with high deuteration rate, this invention can improve the performance of materials and devices through deuteration while also being economically efficient.

[0033] 3) This invention is a further optimization of existing compounds. Compared with similar compounds that have relatively close performance when applied to devices, this invention further reduces the molecular weight of the compound while maintaining device performance no less than that of the prior art. This significantly reduces the sublimation / evaporation temperature of the compound, which can have a positive impact on maintaining the stability of the production line and improving product yield in production practice. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of the organic electroluminescent device of the present invention;

[0035] Figure 2 This is the HPLC chromatogram of compound G3 of this invention;

[0036] Figure 3 This is the 1H NMR spectrum of compound G9 of this invention;

[0037] Figure 4 This is the MS spectrum (m+1 peak) of compound G19 of this invention;

[0038] In the diagram: 1-Anode, 2-Hole injection layer, 3-First hole transport layer, 4-Second hole transport layer, 5-Light emission layer, 6-Hole blocking layer, 7-Electron transport layer, 8-Electron injection layer, 9-Cathode. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings. However, it should be noted that these embodiments are not intended to limit the present invention. Equivalent transformations or substitutions in function, method, or structure made by those skilled in the art based on these embodiments are all within the protection scope of the present invention.

[0040] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0041] Example 1:

[0042]

[0043] The preparation process of compound G3 is as follows:

[0044] S1. Synthetic ZJ1

[0045]

[0046] Add SM2 (80g, 0.409mol, 1eq) and ultra-dry THF (400ml) to a 2L three-necked flask, cool to below -65℃, and add 1.6M n-butyllithium (269ml, 0.43mol, 1.05eq) dropwise. After the addition is complete, keep warm and stir for 1h, then add SM1 (70g, 0.389mol, 0.95eq) in THF (350ml) dropwise. After the addition is complete, slowly raise to room temperature and stir to react overnight.

[0047] The reaction was stopped, quenched with saturated ammonium chloride aqueous solution, stirred and separated, extracted with DCM in aqueous phase, the organic phases were combined, dried with anhydrous sodium sulfate, and the filtrate was concentrated to dryness under reduced pressure. It was then used directly in the next reaction without purification.

[0048] S2. Synthetic ZJ2

[0049]

[0050] Add CP8541-ZJ1 (theoretical 115.4g, 0.389mol, 1eq), triethylsilane (67.84g, 0.5835mol, 1.5eq), and DCM (1000ml) to a 2L three-necked flask, cool to below 0℃, and add trifluoroacetic acid (133g, 1.167mol, 3eq) dropwise. After the addition is complete, stir and react overnight. TLC monitoring shows that ZJ1 has basically disappeared.

[0051] The reaction was stopped, water was added, and the mixture was stirred and separated. The organic phase was washed with water and concentrated to dryness under reduced pressure. 200g of 100-200 mesh silica gel was added to prepare silica gel precipitate. 1.5kg of 100-200 mesh silica gel was packed into a column for column chromatography. The PE / DCM ratio was 1000 / 1 to 100 / 1. The product spot was collected and concentrated to dryness under reduced pressure. 200ml of PE was added, and the mixture was cooled and stirred to crystallize. The mixture was filtered, and the filter cake was dried at 60℃ with a forced air drying process to obtain 70.63g of off-white solid. The overall yield of the two steps was 64.7%.

[0052] S3. Synthesis of ZJ3

[0053]

[0054] Add 60% sodium hydride (30.2 g, 0.755 mol, 3 eq) and ultra-dry THF (300 ml) to a 2 L three-necked flask, cool to below 0 °C, and add a THF (300 ml) solution of ZJ2 (70.63 g, 0.252 mol, 1 eq) dropwise. After the addition is complete, heat to 40 °C and stir for 1 h. Then cool to below 0 °C and add deuterated iodomethane (54.8 g, 0.378 mol, 1.5 eq) dropwise. After the addition is complete, stir and react overnight at room temperature. Monitor the concentration of ZJ2 by ​​HPLC to be ≤0.1%.

[0055] The reaction was stopped, water was slowly added to quench the reaction, and the mixture was stirred and separated. The aqueous phase was extracted with DCM, 100g of 200-300 mesh silica gel was added to prepare sand, 800g of 200-300 mesh silica gel was packed into a column, and column chromatography was performed. The PE / DCM ratio was 1000 / 1 to 100 / 1. The product spot was collected and concentrated under reduced pressure to dryness to obtain 70.5g of colorless oil, with a yield of 94.5%.

[0056] S4. Synthesis of the target product TM

[0057]

[0058] In a 1L three-necked flask, ZJ3 (37.4g, 0.126mol, 1eq), SM3 (45.55g, 0.126mol, 1eq), sodium tert-butoxide (14.5g, 0.1512mol, 1.2eq), XPhos (2.4g, 5.04mmol, 0.04eq), and toluene (500ml) were added. Under N2 protection, palladium acetate (0.56g, 2.52mmol, 0.02eq) was added. After the addition was complete, the temperature was raised to 100℃ and the reaction was stirred. The ZJ3 concentration was monitored by HPLC to be ≤1%.

[0059] The reaction was stopped, and the mixture was filtered through silica gel while hot. The filtrate was concentrated to dryness under reduced pressure. 100 ml of toluene and 400 ml of ethanol were added, and the mixture was stirred and slurried at 65 °C for 2 h. A solid precipitated and was filtered. The filter cake was recrystallized five times with toluene / ethanol (100 ml + 300 ml), and then recrystallized once with toluene (100 ml). The mixture was filtered, and the filter cake was dried in a forced-air dryer at 85 °C to obtain 37 g of off-white solid with an HPLC purity of 99.9475% and a yield of 47.2%.

[0060] Example 2:

[0061]

[0062] The synthesis scheme of compound G75 is similar to that of compound G3, except that the starting material SM3 in step S4 is replaced by SM3'. The synthesis scheme of SM3' is as follows:

[0063]

[0064] In a 1L three-necked flask, a halogenated compound (50g, 0.1741mol, 1eq), an amine (30g, 0.1776mol, 1.02eq), sodium tert-butoxide (20g, 0.21mol, 1.2eq), tritert-tert-butylphosphine (14.1ml, 6.964mmol, 0.04eq), and toluene (500ml) were added. Under N2 protection, tris(2,2-dibenzylacetone)palladium (3.2g, 3.482mmol, 0.02eq) was added. After the addition was complete, the mixture was heated to 100℃ and stirred. The halogenated compound was monitored by HPLC to be ≤1%.

[0065] Stop the reaction, add 400 ml of water, stir and separate the liquids. Extract the aqueous phase with 300 ml of DCM, combine the organic phases, filter through silica gel, concentrate the filtrate to dryness under reduced pressure, add 200 ml of ethanol, stir at 85 °C for 2-3 h, cool to room temperature, filter, and dry the filter cake at 85 °C with forced air to obtain 50.5 g of gray solid SM3', yield 77.2%.

[0066] Compounds G6, G9, G13, G19, G28, G39, G49, G63, G73, and G85 were subsequently prepared using a synthetic scheme similar to that used for G3 and G75, as detailed in Tables 1-1 and 1-2.

[0067] Table 1-1

[0068]

[0069] Table 1-2

[0070]

[0071] The results of the synthesis identification of compounds G3, G6, G9, G13, G19, G28, G39, G49, G63, G73, G75 and G85 are shown in Table 2 below.

[0072] Table 2

[0073]

[0074] Device performance testing:

[0075] Application Example 1: ITO was used as the anode substrate material for the reflective layer, and its surface was sequentially treated with water, acetone, and N2 ions; a 10nm layer doped with 5% N2 was deposited on top of the ITO anode substrate. NDP-9's HT-1 forms a hole injection layer (HIL); 100 nm of HT-1 is deposited on top of the hole injection layer (HIL) to form a first hole transport layer (HTL); compound G3 of the present invention is vacuum-deposited on top of the first hole transport layer (HTL) to form a second hole transport layer (GPL) with a thickness of 10 nm; GH-2 and GH-1 are configured in a 5:5 mass ratio as the light-emitting host material, and GD-1 is used as a dopant material (GD-1 is used in an amount of 8% of the total weight of GH-1 and GH-2) and co-deposited to form a 20 nm thick light-emitting layer on the second hole transport layer (GPL); HB-1 is deposited onto the light-emitting layer to obtain a 20 nm thick hole blocking layer (HBL); ET-1 and LiQ are co-deposited in a 5:5 mass ratio and evaporated onto the hole blocking layer (HBL) to obtain a 30 nm thick layer. An electron transport layer (ETL) is formed; magnesium (Mg) and silver (Ag) are mixed in a 9:1 mass ratio and vapor-deposited onto the electron transport layer (ETL) to form an electron injection layer (EIL) with a thickness of 50 nm; then silver (Ag) is vapor-deposited onto the electron injection layer to form a cathode with a thickness of 100 nm. A 50 nm thick DNTPD is deposited on the cathode sealing layer. In addition, the cathode surface is sealed with a UV-curable adhesive and a sealing film containing a desiccant to protect the organic electroluminescent device from the influence of oxygen or moisture in the atmosphere. Thus, an organic electroluminescent device is prepared.

[0076] The structural formulas of the compounds used in the above preparation process are as follows:

[0077]

[0078] Application Example 2-12: Using other compounds in Table 1-1 and Table 1-2 as the second hole transport layer, and with the other conditions being the same as in Application Example 1, the organic electroluminescent device of Application Example 2-12 was fabricated.

[0079] Comparative Examples 1-4: Organic electroluminescent devices of Comparative Examples 1-4 were fabricated using compounds D1, D2, D3, and D4 as the second hole transport layer, respectively, with other conditions being the same as in Application Example 1.

[0080] The structures of compounds D1, D2, D3, and D4 are as follows:

[0081]

[0082] At a current density of 10 mA / cm 2 The characteristics of the organic electroluminescent devices manufactured under the application example and the organic electroluminescent devices manufactured under the control example were tested under the following conditions. The test results are shown in Table 3 below.

[0083] Table 3

[0084]

[0085] The organic electroluminescent devices prepared in Comparative Examples 1-4 and Application Examples 1-12 were subjected to luminescence lifetime tests, and the luminescence lifetime T97% data (the time for the luminescence brightness to decrease to 97% of the initial brightness) were obtained. The test results are shown in Table 4 (based on the lifetime data of Comparative Example 1).

[0086] Table 4

[0087]

[0088] As shown in Tables 3 and 4, the devices in the application examples of this invention significantly outperformed those in Comparative Examples 1, 2, and 3 in terms of luminous efficiency and lifetime. Compared to Comparative Example 4, their overall performance was no lower than that of Comparative Example 4, and even slightly better. However, compared to compound D4 used in Comparative Example 4, the compounds in the application examples of this invention, by replacing deuterated phenyl groups with deuterated methyl groups, have lower molecular weights, further reducing the sublimation and evaporation temperatures of these compounds. Statistically, under the same evaporation conditions, compared to the evaporation of Comparative Example 4, the evaporation temperatures of compounds G3, G6, G9, G13, G19, G28, G39, G49, G63, G73, G75, and G85 in Application Examples 1-12 were reduced by 30-60°C. This not only directly reduced the heating power consumption of the evaporation source but also had a very positive impact on maintaining the stability of the production line and improving product yield, thus producing a positive effect.

[0089] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An organic electroluminescent compound, characterized in that, Selected from compounds shown in formula (1-1): ； In equation (1-1): R0, R1, R2 and R3 are each independently selected from hydrogen or deuterium, and at least two of them are deuterium; R4, R5, and R6 are each independently selected from methyl or deuterated methyl groups, t, m, and n are each independently represented by 0 or 1, and t+m+n≤1.

2. The organic electroluminescent compound according to claim 1, characterized in that, Of R0-R3, at least R0 and R2 are deuterium, and R1 and R3 are either deuterium or hydrogen.

3. The organic electroluminescent compound as described in claim 2, characterized in that, In R0-R3, R0, R2 and R3 are deuterium, and R1 is either deuterium or hydrogen.

4. The organic electroluminescent compound according to claim 1, characterized in that, Selected from compounds shown in formula (1-2): ； In equation (1-2): R0, R1, R2 and R3 are each independently selected from hydrogen or deuterium, and at least two of them are deuterium; R4 is selected from methyl or deuterated methyl.

5. The organic electroluminescent compound according to claim 1, characterized in that, Selected from compounds shown in formulas (1-3): ； In equation (1-3): R0, R1, R2 and R3 are each independently selected from hydrogen or deuterium, and at least two of them are deuterium; R5 and R6 are each independently selected from methyl or deuterated methyl, m and n are each independently represented by 0 or 1, and m+n≤1.

6. The organic electroluminescent compound according to claim 1, characterized in that, Selected from any of the following compounds: 。 7. An organic electroluminescent device, characterized in that, It includes an anode, a cathode, and an organic layer formed between the anode and the cathode, said organic layer containing an organic electroluminescent compound as described in any one of claims 1-6.

8. The organic electroluminescent device as described in claim 7, characterized in that, 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 sequentially formed between the anode and the cathode, wherein the second hole transport layer is made of a compound as described in any one of claims 1-6.

9. A display device, characterized in that, It includes the organic electroluminescent device as described in claim 7 or 8.

Images