A phosphorescent host material and preparation method thereof and an organic electroluminescent device

Abstract

The present invention provides a phosphorescent host material and a preparation method thereof and an organic electroluminescent device. The present invention belongs to the technical field of organic electroluminescent materials. The light-emitting device containing the phosphorescent host material of the present invention exhibits the characteristics of low driving voltage, high luminous efficiency and long life, and the comprehensive performance of the device is more excellent.

Description

Technical Field

[0001] The invention belongs to the technical field of organic electroluminescent materials, and relates to a phosphorescent main material and a preparation method thereof, and an organic electroluminescent device. Background Art

[0002] Organic electroluminescent (OLED) device technology has the advantages of high brightness, fast response, wide viewing angle, simple process, and flexibility, and has attracted much attention in the fields of new display technology and new lighting technology.

[0003] At present, in OLED devices prepared using phosphorescent materials, electrophosphorescence requires the use of host-guest doping technology. However, when triazine derivatives in the prior art are used as host materials, there is no good balance in device voltage, luminous efficiency and device life.

[0004] Therefore, developing stable and efficient host materials so that the devices exhibit excellent comprehensive performance in terms of driving voltage, luminous efficiency and life span has very important practical application value. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a phosphorescent host material and a preparation method thereof and an organic electroluminescent device. The light-emitting device containing the phosphorescent host material of the present invention exhibits the characteristics of low driving voltage, high luminous efficiency and long life, and the overall performance of the device is more excellent.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In one aspect, the present invention provides a phosphorescent host material having a structure of Formula 1

[0008]

[0009] in,

[0010] R1-R2 are each independently selected from deuterium;

[0011] R3-R5 are each independently selected from deuterium, unsubstituted or deuterium-substituted phenyl;

[0012] n and q are independently 0, 1, 2, 3;

[0013] m is 0, 1, 2, 3, 4;

[0014] p and o are independently 0, 1, 2, 3, 4, 5;

[0015] When o, p, and q are greater than 1, multiple R3, multiple R4, or multiple R5 groups are the same or different;

[0016] Ar and Ar1 are independently selected from unsubstituted or deuterium-substituted C6-C24 aryl, and unsubstituted or deuterium-substituted C12-C18 heteroaryl containing one heteroatom of O, S or N.

[0017] Preferably, the phosphorescent host material has any of the following structures:

[0018]

[0019] .

[0020] Preferably, Ar and Ar1 are independently selected from the following groups which are unsubstituted or substituted with deuterium:

[0021] , “*” indicates the connection between the group and the carbon on the ring;

[0022] In the present invention, “unsubstituted or substituted with deuterium” means substituted with one deuterium, two deuteriums, or a plurality of deuteriums, or having no substituent.

[0023] More specifically, the phosphorescent host material is selected from any one of the following compounds:

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045] .

[0046] In the present invention, the synthesis route of the phosphorescent host material is as follows:

[0047]

[0048] Reactant 1-1 (1.0 eq) and reactant 1-2 (1.0-1.8 eq) and potassium acetate (2.0-3.0 eq) were added to the reaction flask, followed by 1,4-dioxane, palladium catalyst (0.02-0.10 eq), phosphine ligand (0.10-0.15 eq), and the resultant was heated to 100-140°C and stirred for 8-14 hours. Celite was used for hot suction filtration, and the filtrate was cooled to room temperature, and then water was added to the filtrate for washing. After separation, the organic phase was retained, and the aqueous phase was extracted with ethyl acetate; the combined organic layer was then dried with magnesium sulfate and purified by column chromatography to obtain intermediate 1.

[0049] The intermediate 1 (1.0 eq) and the reactant 1-3 (1.0-1.5 eq) were added to the reaction flask, followed by a mixed solution of toluene, ethanol, and water (volume ratio of 3:1:1), a palladium catalyst (0.01-0.03 eq), a base (2.0-3.0 eq), a phosphine ligand (0.10-0.20 eq), and cesium carbonate (2.0-3.0 eq), and the temperature was raised to 80-120 ° C, and the reaction was refluxed for 4-18 hours. The diatomaceous earth was used for hot suction filtration, and after the filtrate was cooled to room temperature, water was then added to the filtrate for washing, and the organic phase was retained after separation, and the aqueous phase was extracted with ethyl acetate; the combined organic layer was then dried with magnesium sulfate, and purified by column chromatography to obtain Formula 1.

[0050] in,

[0051] Hal, Hal1 are selected from Cl, Br;

[0052] R1-R5, Ar, Ar1, n, m, o, p, and q have the meanings given above;

[0053] The base can be: K2CO3 (potassium carbonate), K3PO4 (potassium phosphate), Na2CO3 (sodium carbonate), CsF (cesium fluoride), Cs2CO3 (cesium carbonate) or t-BuONa (sodium tert-butoxide);

[0054] The palladium catalyst may be: Pd2(dba)3 (tris(dibenzylideneacetone)dipalladium), Pd(PPh3)4 (tetrakis(triphenylphosphine)palladium), PdCl2 (palladium dichloride), PdCl2(dppf) ([1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium), Pd(OAc)2 (palladium acetate), Pd(PPh3)2Cl2 (bis(triphenylphosphine)dichloropalladium) or NiCl2(dppf) ((1,1'-bis(diphenylphosphino)ferrocene)nickel dichloride);

[0055] The phosphine ligand can be: P(t-Bu)3 (tri-tert-butylphosphine), X-phos (2-cyclohexyl-2,4,6-triisopropylbiphenyl), PET3 (triethylphosphine), PMe3 (trimethylphosphine), PPh3 (triphenylphosphine), KPPh2 (potassium diphenylphosphonate) or P(t-Bu)2Cl (di-tert-butylphosphine chloride).

[0056] On the other hand, the present invention provides an organic electroluminescent device, comprising a first electrode, a second electrode and at least one organic layer disposed between the first electrode and the second electrode, wherein the organic layer comprises a light-emitting layer, and the light-emitting layer comprises the phosphorescent host material as described above.

[0057] Preferably, the light-emitting layer further comprises a doping material.

[0058] The organic material layer of the organic light-emitting device of the present invention may be formed into a single-layer structure, but may also be formed into a multilayer structure having two or more organic material layers. For example, the organic light-emitting device of the present invention may have a structure including a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting auxiliary layer, a light-emitting layer, an electron transport layer, an electron injection layer, a hole blocking layer, etc. as organic material layers. However, the structure of the organic light-emitting device is not limited thereto, and may include a smaller number of organic material layers or a larger number of organic material layers.

[0059] In another aspect, the present invention provides an organic light-emitting device, comprising the organic electroluminescent device as described above.

[0060] The organic light-emitting device described in the present invention includes but is not limited to flat panel displays, computer monitors, medical monitors, televisions, billboards, lights for internal or external lighting and / or signals, head-up displays, fully transparent or partially transparent displays, flexible displays, laser printers, telephones, mobile phones, photo albums, personal digital assistants (PDAs), wearable devices, laptops, digital cameras, camcorders, viewfinders, microdisplays, three-dimensional displays, virtual reality or augmented reality displays, vehicles, video walls including multiple displays tiled together, theater or stadium screens, light therapy devices and signs, etc.

[0061] The beneficial technical effects of the present invention are:

[0062] The parent core of the compound of the invention is a triazine structure directly bonded to a carbazole aromatic ring. The direct bonding of triazine and carbazole aromatic rings can provide an effective conjugation effect. Meanwhile, the carbazole aromatic ring is not substituted by other groups, which can avoid the increase of intermolecular interactions caused by unnecessary groups, thereby reducing the transmission of charges, increasing the starting voltage and reducing the luminous efficiency, which is not conducive to improving the overall performance of the device. The biphenyl structure substituted by phenyl is introduced into the 9th position of the carbazole in the parent core, which can enhance the bulk conjugation effect. Meanwhile, the spatiality of the structure can be enhanced because the position of the phenyl substitution is in the ortho position, so that the molecules are not easy to aggregate and crystallize, have good film-forming properties and thermal stability, and improve the service life of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 It is the hydrogen nuclear magnetic resonance spectrum of compound 3 in Example 1 of the present invention. DETAILED DESCRIPTION

[0064] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0065] Embodiment 1:

[0066]

[0067] Reactant 3-1 (20 mmol, CAS No.: 1804904-94-6) and reactant 1-2 (50 mmol, CAS No.: 73183-34-3) and potassium acetate (40 mmol) were added to the reaction flask, followed by 1,4-dioxane, Pd(PPh3)4 (1 mmol), X-phos (2 mmol), and then the resultant was heated to 110°C and stirred for 10 hours. Celite was used for hot suction filtration, and the filtrate was cooled to room temperature, and then water was added to the filtrate for washing. After separation, the organic phase was retained, and the aqueous phase was extracted with ethyl acetate; the combined organic layer was then dried with magnesium sulfate and purified by column chromatography to obtain intermediate 3 (yield: 73.8%).

[0068] The intermediate 3 (20 mmol) and the reactant 3-3 (25 mmol, CAS No.: 80984-79-8) were added to the reaction flask, followed by a mixed solution of toluene, ethanol and water (volume ratio of 3:1:1), Pd(PPh3)4 (0.4 mmol), Na2CO3 (40 mmol), X-phos (3 mmol) and cesium carbonate (40 mmol), and the temperature was raised to 100°C, and the reaction was refluxed for 10 hours. Celite was used for hot filtration, and the filtrate was cooled to room temperature, and then water was added to the filtrate for washing. After separation, the organic phase was retained, and the aqueous phase was extracted with ethyl acetate; the combined organic layer was then dried with magnesium sulfate and purified by column chromatography to obtain compound 3 (9.43 g, yield: 75.2%, test value MS (ESI, m / Z): [M+H] + = 626.99).

[0069] The H NMR spectrum of compound 3 is as follows Figure 1 shown.

[0070] Characterization:

[0071] HPLC purity: >99.8%.

[0072] Elemental Analysis:

[0073] Theoretical values: C, 86.24; H, 4.82; N, 8.94.

[0074] Test values: C, 86.16; H, 4.91; N, 8.96.

[0075] Example 2-155

[0076] The following compounds were synthesized by referring to the synthesis method of Example 1 and tested using a Waters XEVO TQD mass spectrometer, which has low precision. The ESI source was used for testing, and the mass spectrometry test values ​​are shown in Table 1 below.

[0077] Table 1 Mass spectrum of Example 2-155

[0078]

[0079]

[0080]

[0081] In addition, it should be noted that other compounds of the present invention can be obtained by referring to the synthesis methods of the above-mentioned embodiments, so they are not listed one by one here.

[0082] Device Example 1: Preparation of Green Organic Electroluminescent Device

[0083] a. ITO anode: Wash the ITO (indium tin oxide)-Ag-ITO (indium tin oxide) glass substrate with a coating thickness of 150nm in distilled water twice, ultrasonically wash for 30 minutes, and then repeatedly wash it with distilled water twice, ultrasonically wash for 10 minutes, and bake it in a vacuum oven at 220℃ for 2 hours. After baking, cool it down and it can be used. Use this substrate as the anode, use an evaporation machine to perform the evaporation device process, and evaporate other functional layers on it in sequence.

[0084] b. HIL (hole injection layer): vacuum evaporation of hole injection layer materials HT and P-dopant at an evaporation rate of 1Å / s, with the evaporation rate ratio of HT to P-dopant being 97:3 and the thickness being 10nm;

[0085] c. HTL (hole transport layer): 120 nm of HT was vacuum-deposited on the hole injection layer at a deposition rate of 1.5 Å / s as the hole transport layer;

[0086] d. Prime (luminescence auxiliary layer): 35nm of Prime was vacuum evaporated on the hole transport layer at a deposition rate of 0.5Å / s as a luminescence auxiliary layer;

[0087] e. EML (light-emitting layer): Then, on the above-mentioned light-emitting auxiliary layer, a dual host material (compound 3 provided by the present invention is the first host compound, Host-2 is used as the second host compound) and a dopant material (Dopant) with a total thickness of 40nm are vacuum-deposited at a deposition rate of 1Å / s as a light-emitting layer, wherein the deposition rate ratio of the first host compound, the second host compound and the dopant compound is 44:44:12.

[0088] f. HB (hole blocking layer): A hole blocking layer with a thickness of 5.0 nm was vacuum-deposited at a deposition rate of 0.5 Å / s.

[0089] g. ETL (electron transport layer): ET and Liq were vacuum evaporated to a thickness of 30 nm at an evaporation rate of 1 Å / s as the electron transport layer. The evaporation rate ratio of ET to Liq was 1:1.

[0090] h. EIL (electron injection layer): 1.0 nm Yb film layer was evaporated at a deposition rate of 0.5 Å / s to form an electron injection layer.

[0091] i. Cathode: 13 nm of magnesium and silver were evaporated at an evaporation rate ratio of 1 Å / s, and the evaporation rate ratio was 1:9 to obtain an OLED device.

[0092] j. Light extraction layer: CPL with a thickness of 65 nm was vacuum-deposited on the cathode at a deposition rate of 1 Å / s as a light extraction layer.

[0093] k. Package the substrate after evaporation. First, use the glue coating equipment to coat the cleaned cover with UV glue, then move the coated cover to the pressing section, place the evaporation-deposited substrate on the upper end of the cover, and finally bond the substrate and cover with the bonding equipment, and complete the light curing of the UV glue.

[0094] The material structure used in the above device is as follows:

[0095]

[0096] Referring to the preparation method provided in the above device example 1, the corresponding compounds in examples 2 to 155 are substituted for compound 3 in device example 1 and are recorded as device examples 2 to 155 respectively.

[0097] Device Comparison Examples 1-17:

[0098] Referring to the preparation method provided in the above device example 1, comparative compounds 1 to comparative compounds 17 replace compound 3 in device example 1, and are recorded as device comparative examples 1-17, respectively, wherein the chemical structural formulas of comparative compounds 1-17 are as follows:

[0099]

[0100]

[0101] The driving voltage, luminous efficiency and life of the organic electroluminescent devices obtained from the above device embodiments 1-155 and device comparison examples 1-17 were characterized at a brightness of 15000 (nits). The test results are shown in Table 2 below.

[0102] Table 2 Device test results

[0103]

[0104]

[0105]

[0106]

[0107]

[0108]

[0109]

[0110] As can be seen from Table 2, the organic electroluminescent device examples 1-155 prepared using the light-emitting layer main body provided by the present invention exhibits the characteristics of low driving voltage, high luminous efficiency and long life compared with the device prepared using the comparative compound 1-17, and the overall performance of the device is more excellent.

[0111] Among them, the comparison compound 1 and the compound 3 are parallel comparative examples, and the difference is only in the group bonded at the 9-position of carbazole. The comparison compound has a 9,9-dimethylfluorenyl group, and the present invention is a terphenyl group substituted with a phenyl phenyl group. Since the group used in the present invention has a better conjugation effect, it has a strong charge transfer ability, thereby reducing the starting voltage of the device and improving the efficiency of the organic electroluminescent device.

[0112] Comparative Compound 2, Comparative Compound 5, and Comparative Compound 6 are all parallel comparative examples with Compound 3, and the difference lies in the bonding mode of the carbazole group and the triazine group. In the comparative compounds, carbazole needs to be linked through the arylide group, and the compound in the present invention directly bonds the aromatic ring of carbazole to the triazine group, which can form a more effective conjugated system, which helps charge transfer, thereby improving the overall performance of the device. Similarly, Comparative Compound 17 and Compound 169, Comparative Compound 3, Comparative Compound 4, Comparative Compound 7, Comparative Compound 8 and Compound 5 in the present invention are also parallel comparative examples, and the difference also lies in the bonding mode of the carbazole group and the triazine group. In addition, compared with Compound 5, the comparative compound also introduces more phenyl groups to replace at different positions, which will more easily cause energy loss of the structure, which is not conducive to the life of the device.

[0113] Comparative compound 9 and compound 34 are parallel comparative examples, and the only difference is the group bonded to the 9-position of carbazole. Compared with the comparative compound, the method of replacing the biphenyl with phenyl in the present invention can not only provide a more effective conjugation method but also enhance the spatiality of the structure, making it difficult for the molecules to aggregate and crystallize, and having good film-forming properties and thermal stability, thereby improving the service life of the device.

[0114] Comparative compounds 12 and 35, and comparative compounds 14 and 195 are parallel comparative examples, respectively, and the only difference is whether the biphenyl group bonded to the 9-position of carbazole is replaced by a phenyl group. Since an additional phenyl group is introduced in the present invention, a more effective conjugation effect is provided and the spatiality of the structure is enhanced, thereby improving the overall performance of the device.

[0115] Comparative compound 15 and compound 196 are parallel comparative examples, the only difference being whether the aromatic ring of carbazole is replaced by a phenyl group. The spatial effect caused by the introduction of an extra phenyl group in comparative compound 15 is not significant and may increase intermolecular interactions, thereby reducing charge transfer, reducing luminous efficiency and increasing the starting voltage, which is not conducive to improving the overall performance of the device.

[0116] Comparative compound 16 and compound 264 are parallel comparative examples, the only difference being that the phenyl group is substituted on the aromatic ring of carbazole or on the biphenyl group at the 9-position of carbazole. From the device data, it can be seen that the compounds conforming to the general formula of the present invention are more excellent in voltage, luminous efficiency and lifespan. The reason is that the position of the phenyl group substitution in the present invention can provide a stronger conjugation effect and greater spatiality, which makes the charge transfer faster while inhibiting crystallization.

[0117] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A phosphorescent host material, characterized in that: The phosphorescent host material has a structure of Formula 1 in, R1-R2 are each independently selected from deuterium; R3-R5 are each independently selected from deuterium, unsubstituted or deuterium-substituted phenyl; n and q are independently 0, 1, 2, 3; m is 0, 1, 2, 3, 4; p and o are independently 0, 1, 2, 3, 4, 5; When o, p, and q are greater than 1, multiple R3, multiple R4, or multiple R5 groups are the same or different; Ar and Ar1 are independently selected from unsubstituted or deuterium-substituted C6-C24 aryl, and unsubstituted or deuterium-substituted C12-C18 heteroaryl containing one heteroatom of O, S or N.

2. The phosphorescent host material according to claim 1, characterized in that: The phosphorescent host material has any of the following structures: 。 3. The phosphorescent host material according to claim 1 or 2, characterized in that: Ar and Ar1 are independently selected from the following groups which are unsubstituted or substituted with deuterium: ， "*" indicates the attachment point of the group to a ring carbon.

4. The phosphorescent host material according to claim 1, characterized in that: The phosphorescent host material is selected from any one of the following compounds: 。 5. An organic electroluminescent device, characterized in that: The organic electroluminescent device comprises a first electrode, a second electrode and at least one organic layer disposed between the first electrode and the second electrode, wherein the organic layer comprises a light-emitting layer, and the light-emitting layer comprises the phosphorescent host material according to any one of claims 1 to 4.

6. An organic light-emitting device, characterized in that: The organic light-emitting device comprises the organic electroluminescent device as claimed in claim 5.

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