Phosphorescent host material, preparation method and organic electroluminescent device

Abstract

The present invention belongs to the technical field of organic optoelectronic materials, and discloses a phosphorescent host material, a preparation method and an organic electroluminescent device. The phosphorescent host material compound is substituted with a carbazolyl group and a triazine group at the 1-position and 2-position of a dibenzoheterocycle, and a phenyl group is introduced into the aromatic ring on the same side of the substituted dibenzoheterocycle. The molecular structure conforming to the general formula (1) or general formula (2) has low molecular symmetry, strong structural rigidity and large steric hindrance, which is beneficial to improving the energy of the triplet state, avoiding the occurrence of energy back-transfer, and at the same time can also reduce the internal energy loss of the molecule, making the overall performance of the device more excellent; in addition, the structure conforming to the general formula of the present invention is more conducive to charge transport, thereby reducing the driving voltage and enhancing the luminous efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic optoelectronic materials, and in particular, relates to a phosphorescent host material, a preparation method, and an organic electroluminescent device containing the same. Background Art

[0002] An organic electroluminescent (OLED) device is a self-luminous device, and due to its characteristics such as low driving voltage, high brightness, fast response time, wide viewing angle, high resolution, simple process, flexibility, and bendability, it has attracted much attention in the fields of new display technologies and lighting technologies.

[0003] Currently, the organic electroluminescent device (OLED) display technology has been applied in fields such as smart phones and tablet computers, and will also be extended to large-size application fields such as televisions. However, compared with the actual product application requirements, the performance of OLEDs such as luminous efficiency and service life still needs to be further improved.

[0004] Currently, the phosphorescent host materials used in OLED devices are mainly a class of derivatives with a triazine-carbazole as the mother nucleus. Although the types of structures vary widely, it is still a great challenge to improve the comprehensive performance of the devices, and it is difficult to achieve a good balance among the driving voltage, luminous efficiency, and lifetime. Therefore, developing stable and efficient host materials to improve the comprehensive performance in devices has important practical application value and is also one of the technical problems that need to be solved urgently by those skilled in the art. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a phosphorescent host material, a preparation method, and an organic electroluminescent device. When the phosphorescent host material is applied to a light-emitting device, it exhibits low driving voltage, high luminous efficiency, and long lifetime characteristics, and the obtained green organic electroluminescent device has more excellent comprehensive performance.

[0006] To solve the above problems, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a phosphorescent host material, and the phosphorescent host material has a compound structure shown in Formula 1 or Formula 2:

[0008] ;

[0009] Wherein, X is selected from O or S;

[0010] R, R1, and R2 are each independently selected from deuterium;

[0011] n takes a numerical value of 0, 1, 2, 3, 4, 5, 6, 7, 8;

[0012] Both m and p take values of 0, 1, 2, 3, 4, 5;

[0013] q takes values of 0, 1;

[0014] Ar is an unsubstituted or deuterium-substituted phenyl group;

[0015] Ar1 and Ar2 are independently selected from unsubstituted or deuterium-substituted C6-C 24 aryl groups, unsubstituted or deuterium-substituted C containing one heteroatom of O, S or N 12 -C 18 heteroaryl groups.

[0016] In one embodiment of the present invention, the phosphorescent host material has any one of the following structures:

[0017]

[0018] .

[0019] In one embodiment of the present invention, Ar1 and Ar2 are independently selected from the following unsubstituted or deuterium-substituted groups:

[0020]

[0021] "*" represents the connection point of the group to the carbon on the ring.

[0022] In the present invention, the term "unsubstituted or deuterium-substituted" means that the group is substituted with one, two or more, up to the maximum number of substituents, of deuterium, or has no substituents.

[0023] In one embodiment of the present invention, the phosphorescent host material is selected from any one of the following compounds:

[0024]

[0025]

[0026] 。

[0027] The above are some specific structural forms of the phosphorescent host material compounds, but are not limited to the listed chemical structures. All compounds with simple transformations of groups within the defined ranges based on the general structural formulas shown in Formula (1) or Formula (2) should be included.

[0028] In a second aspect, the present invention also provides a method for synthesizing the above phosphorescent host material compound, comprising the following steps:

[0029] The steps for synthesizing the compound shown in Structure 1 are as follows:

[0030] ;

[0031] By replacing Reactant 1-a in the above Structure 1 with 2-a, the compound shown in Structure 2 can be synthesized;

[0032] The steps for synthesizing the compound shown in Structure 2 are as follows:

[0033] ;

[0034] Wherein, Hal, Hal1, and Hal2 are selected from F, Cl, Br, and I;

[0035] R, R1, R2, n, m, p, q, Ar, Ar1, and Ar2 have the definitions given above.

[0036] Specifically, the steps for synthesizing the compound shown in Structure 1 or Structure 2 include:

[0037] After dissolving reactant 1-a or 2-a (1.0 eq) and reactant 1-b (0.8 - 1.0 eq) in xylene, a palladium catalyst (0.01 - 0.05 eq), a phosphorus ligand (0.02 - 0.15 eq), and a basic salt (2.0 - 2.4 eq) are added; after the addition, the reaction temperature is slowly raised to 100 - 120 °C, and the mixture is stirred for 8 - 12 h; the reaction is detected by thin-layer chromatography. After determining the completion of the reaction, water and dichloromethane are added for extraction and liquid separation. After combining the organic phases, they are concentrated, and purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:4 - 1:8) to obtain intermediate 1-c or intermediate 2-c.

[0038] Note: In this reaction step, there may be two halogens in raw material 1-a or 2-a. On the one hand, taking advantage of the reactivity order of I > Br > Cl, and on the other hand, controlling the reaction site by controlling the reaction conditions, and purifying the reaction by column chromatography to obtain the target compound. Refer to the common general knowledge as follows:

[0039] "Organotransition Metal Chemistry" (Original Sixth Edition), Robert H. Crabtree, Publisher: East China University of Science and Technology Press, Shanghai, Publication Date: 2017-09-00, ISBN: 978 - 7-5628-5111-0, Page 388.

[0040] "Experimental Course of Organic Chemistry and Optoelectronic Materials", Chen Runfeng, Publisher: Southeast University Press, Publication Date: 2019-11-00, ISBN: 9787564184230, Page 174.

[0041] Dissolve intermediate 1-c or intermediate 2-c (1.0 eq), reactant intermediate 1-d (1.0 - 1.3 eq), palladium catalyst (0.01 - 0.02 eq), and potassium acetate (2.0 - 3.0 eq) in DMF, raise the temperature to 80 - 100 °C, react for 6 - 8 h, and remove the solvent using a rotary evaporator. The residue is added to dichloromethane, stirred, filtered, and purified by column chromatography to obtain intermediate 1-e or intermediate 2-e;

[0042] Add intermediate 1-e or intermediate 2-e (1.0 eq) and reactant 1-f (1.0 - 1.3 eq) into a reaction flask, and then add a mixed solution of toluene, ethanol, and water (volume ratio 3:1:1). Add a palladium catalyst (0.01 - 0.02 eq) and a basic salt (2.0 - 3.0 eq), heat up to 100 - 120 °C, and reflux for 6 - 18 hours. Filter while hot using diatomaceous earth. After the filtrate cools to room temperature, add water to the filtrate for washing. After liquid separation, retain the organic phase and extract the aqueous phase with ethyl acetate. Then dry the combined organic layer using magnesium sulfate and purify by column chromatography to obtain the compound with the structure shown in Formula 1 or Formula 2.

[0043] In one embodiment of the present invention, the basic salt is selected from one or more of K2CO3 (potassium carbonate), K3PO4 (potassium phosphate), Na2CO3 (sodium carbonate), CsF (cesium fluoride), Cs2CO3 (cesium carbonate), and t-BuONa (sodium tert-butoxide).

[0044] In one embodiment of the present invention, the palladium catalyst is selected from one or more of Pd2(dba)3 (bis(tri - dibenzylideneacetone)dipalladium(0)), Pd(PPh3)4 (tetrakis(triphenylphosphine)palladium(0)), PdCl2 (palladium(II) chloride), PdCl2(dppf) ([1,1'-bis(diphenylphosphino)ferrocene]palladium(II) chloride), Pd(OAc)2 (palladium(II) acetate), Pd(PPh3)2Cl2 (bis(triphenylphosphine)palladium(II) chloride), and NiCl2(dppf) ((1,1'-bis(diphenylphosphino)ferrocene)nickel(II) chloride).

[0045] In one embodiment of the present invention, the phosphorus ligand is selected from one or more of P(t - Bu)3 (tri - tert - butylphosphine), X - phos (2 - cyclohexylphosphino - 2,4,6 - triisopropylbiphenyl), PET3 (triethylphosphine), PMe3 (trimethylphosphine), PPh3 (triphenylphosphine), KPPh2 (potassium diphenylphosphide), and P(t - Bu)2Cl (di - tert - butylchlorophosphine).

[0046] In a third aspect, the present invention also provides an organic electroluminescent device comprising the above - mentioned phosphorescent host material.

[0047] In one embodiment of the present invention, the green organic electroluminescent device comprises an anode, a hole injection layer, a hole transport layer, a light - emitting auxiliary layer, a light - emitting layer, a hole - blocking layer, an electron transport layer, an electron injection layer, and a cathode which are arranged in sequence; the light - emitting layer contains the phosphorescent host material.

[0048] In one embodiment of the present invention, the light - emitting layer contains the phosphorescent host material as the first host compound, Host - 2 as the second host compound, and a doping material.

[0049] Advantageous technical effects of the present invention:

[0050] The present invention provides a phosphorescent host material compound, in which the 1-position and 2-position of the dibenzoheterocycle are substituted with carbazolyl and triazine groups, and a phenyl group is introduced on the aromatic ring on the same side where the dibenzoheterocycle is substituted. The structural molecules conforming to the general formula (1) and general formula (2) of the present invention have low molecular symmetry, strong structural rigidity, and large steric hindrance, which are beneficial to improving the energy of the triplet state, avoiding the occurrence of energy back transfer, and at the same time reducing the internal energy loss of the molecule, making the overall performance of the device more excellent; in addition, the structure conforming to the general formula of the present invention is more conducive to charge transport, thereby reducing the driving voltage and enhancing the luminous efficiency. Description of the Drawings

[0051] Figure 1 1H NMR spectrum of compound 282 in Example 1 of the present invention. Detailed Embodiments

[0052] The technical solutions of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only for illustrative and explanatory purposes of the present invention, and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection of the present invention.

[0053] Unless otherwise specified, the raw materials and reagents used in the following embodiments are all commercially available products.

[0054] Example 1

[0055] Preparation of compound 282:

[0056] ,

[0057] Reactants 282-a (1.0 eq, CAS No.: 2765550-02-3) and 282-b (0.8 eq, CAS No.: 86-74-8) were dissolved in xylene, then Pd(PPh3)4 (0.02 eq), X-Phos (0.01 eq), and t-BuONa (2.0 eq) were added; after addition, the reaction temperature was slowly raised to 100 °C, and the mixture was stirred for 8 h; the reaction was detected by thin layer chromatography. After determining the end of the reaction, water and dichloromethane were added for extraction and liquid separation. After combining the organic phases and concentrating, the intermediate 282-c was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:4).

[0058] Dissolve intermediate 282-c (1.0 eq), reactant intermediate 282-d (1.3 eq, CAS No.: 73183-34-3), Pd(PPh3)4 (0.01 eq) and potassium acetate (2.0 eq) in DMF, heat to 90 °C, react for 8 h, and remove the solvent using a rotary evaporator. Add dichloromethane to the residue, stir and filter, and purify by column chromatography to obtain intermediate 282-e;

[0059] Add intermediate 282-e (1.0 eq) and reactant 282-f (1.3 eq, CAS No.: 3842-55-5) to a reaction flask, then add a mixed solution of toluene, ethanol and water (volume ratio 3:1:1), add Pd(PPh3)4 (0.01 eq) and t-BuONa (2.0 eq), heat to 120 °C, and reflux for 10 hours. Filter while hot using diatomaceous earth, cool the filtrate to room temperature, then add water to the filtrate for washing, separate the layers and retain the organic phase, and extract the aqueous phase with ethyl acetate; then dry the combined organic layers with magnesium sulfate and purify by column chromatography to obtain compound 282 (yield: 73.9%, measured value MS(ESI, m / z): [M+H]+ = 656.33).

[0060] The 1H NMR spectrum of compound 282 is as Figure 1 shown.

[0061] Characterization: HPLC purity: >99.8%.

[0062] Elemental analysis:

[0063] Theoretical values: C, 82.29; H, 4.30; N, 8.53; S, 4.88

[0064] Measured values: C, 82.21; H, 4.33; N, 8.57; S, 4.96

[0065] Device Example 1

[0066] Prepare a green organic light-emitting device:

[0067] a. ITO anode: Wash an ITO (indium tin oxide)-Ag-ITO (indium tin oxide) glass substrate with a coating thickness of 150 nm twice in distilled water, ultrasonically wash for 30 min, then wash repeatedly twice with distilled water, ultrasonically wash for 10 min, and bake in a vacuum oven at 220 °C for 2 hours. After baking, cool to room temperature for use. Using this substrate as the anode, perform evaporation device process using an evaporation machine, and evaporate other functional layers thereon in sequence.

[0068] b. HIL (Hole Injection Layer): Vacuum deposit the hole injection layer materials HT and P-dopant at a deposition rate of 1 Å / s. The deposition rate ratio of HT and P-dopant is 97:3, and the thickness is 10 nm.

[0069] c. HTL (Hole Transport Layer): Vacuum deposit 120 nm of HT as the hole transport layer on the hole injection layer at a deposition rate of 1.5 Å / s.

[0070] d. Prime (Luminescence-Assisting Layer): Vacuum deposit 35 nm of Prime as the luminescence-assisting layer on the hole transport layer at a deposition rate of 0.5 Å / s.

[0071] e. EML (Emitting Layer): Then, on the above-mentioned luminescence-assisting layer, vacuum deposit a total thickness of 30 nm of a double-host material (Compound 282 provided by the present invention is the first host compound, and Host-2 is the second host compound) and a doping material (Dopant) as the emitting layer at a deposition rate of 1 Å / s. The deposition rate ratio of the first host compound, the second host compound, and the doping material is 44:44:12.

[0072] f. HB (Hole Blocking Layer): Vacuum deposit a 5.0 nm-thick HB as the hole blocking layer at a deposition rate of 0.5 Å / s.

[0073] g. ETL (Electron Transport Layer): Vacuum deposit a 30 nm-thick ETL and Liq as the electron transport layer at a deposition rate of 1 Å / s. The deposition rate ratio of ETL and Liq is 1:1.

[0074] h. EIL (Electron Injection Layer): Deposit a 1.0 nm-thick Yb film at a deposition rate of 0.5 Å / s to form the electron injection layer.

[0075] i. Cathode: Deposit 13 nm of magnesium and silver at a deposition rate ratio of 1 Å / s and a deposition rate ratio of 1:9 to obtain the OLED device.

[0076] j. Light Extraction Layer: Vacuum deposit a 65 nm-thick CPL on the cathode at a deposition rate of 1 Å / s as the light extraction layer.

[0077] k. Package the substrate after deposition. First, use a coating device to coat the cleaned cover plate with UV glue, then move the coated cover plate to the lamination section, place the deposited substrate on the upper end of the cover plate, and finally laminate the substrate and the cover plate under the action of a laminating device, while completing the photo-curing of the UV glue.

[0078] The material structures used in the above devices are as follows:

[0079] 。

[0080] Device Example 2 - 108:

[0081] It is only necessary to replace the first host material in Device Example 2 - 108 in Table 1 with Compound 282 in Device Example 1.

[0082] Device Comparative Examples 1 - 23:

[0083] Referring to the preparation method provided in Device Example 1 above, replace Compound 282 in Device Example 1 with Comparative Compounds 1 - 23, and denote them as Device Comparative Examples 1 - 23 respectively. The chemical structural formulas of Comparative Compounds 1 - 23 are as follows:

[0084]

[0085]

[0086]

[0087] 。

[0088] Characterize the driving voltage, luminous efficiency, and lifetime of the organic electroluminescent devices obtained from Device Examples 1 - 108 and Device Comparative Examples 1 - 23 above at a brightness of 15,000 (nits). The test results are shown in Table 1 below.

[0089] Table 1 Device Test Results

[0090]

[0091]

[0092]

[0093]

[0094]

[0095]

[0096] As can be seen from Table 1, the organic electroluminescent devices prepared using the phosphorescent host material provided by the present invention as the host of the light-emitting layer (Device Examples 1 - 108) exhibit the characteristics of low driving voltage, high luminous efficiency, and long lifetime compared with the devices prepared using Comparative Compounds 1 - 23 as the host of the light-emitting layer, and the comprehensive performance of the devices is more excellent.

[0097] Among them, comparison compound 2 and comparison compound 3 are parallel comparison examples with compound 246 of the present invention. Compared with compound 246, the introduction of a dibenzofuran group in comparison compound 2 on the aromatic ring of the parent nucleus dibenzofuran of the present invention not only reduces the asymmetry of the molecule, but also enhances the coupling between the structures to cause molecular stacking, increases the molecular crystallinity, and causes the device efficiency to roll off significantly and reduce the life span. Compared with the parent nucleus of the present invention, comparison compound 3 introduces one less phenyl, and the molecular weight is small, resulting in poor thermal stability, which makes the overall performance of the device poor. At the same time, the phenyl introduced by the present invention can also further improve the electron mobility and reduce the driving voltage of the device.

[0098] Comparative compound 6 and compound 329 of the present invention are parallel comparative examples, and the only difference between the two is the substitution position of the triazine group. From the device data in Table 1, it can be seen that the overall performance of the present invention is more excellent, because the molecular space provided by the present invention is more stereoscopic, the energy of the triplet state is increased, the phenomenon of energy back transmission is avoided, and the overall performance of the device is better. Comparative compound 8 and compound 334 of the present invention, comparative compound 9 and compound 335 of the present invention, comparative compound 10 and compound 337 of the present invention, comparative compound 11 and compound 338 of the present invention, comparative compound 12 and compound 277 of the present invention, comparative compound 13 and compound 369 of the present invention, comparative compound 16 and compound 1 of the present invention, comparative compound 19 and compound 2 of the present invention also have structural defects of poor molecular stereoscopic properties.

[0099] Comparative compound 18 and compound 1 of the present invention are parallel comparative examples, and the only difference is the group substituted at the 4-position of dibenzofuran. Compared with the carbazole group, the phenyl group has a smaller molecular weight and has less effect on the thermal stability of the molecule. Secondly, the phenyl group has better compatibility and can be mixed with many other organic materials (such as dopants), which helps to improve the overall performance of the device.

[0100] Comparative compound 15 is closer to compound 1 of the present invention. In comparative compound 15, triazine and dibenzofuran are connected by phenylene groups instead of direct bonding as in the present invention. The stereochemistry of the molecule is relatively small, and the phenylene groups in the middle will also cause rotation inside the molecule and lose energy, affecting the overall performance of the device.

[0101] Comparative compound 23 and compound 281 are parallel comparative examples. The substituent groups on one side of dibenzothiophene are the same but the substitution positions are different. From the device data, it can be seen that the compounds conforming to the general formula of the present invention perform better in terms of device voltage, luminous efficiency and life. The possible reason is that the connection method in the general formula of the present invention is more conducive to electron delocalization, so that the molecular structure can be stabilized, which is beneficial to charge transfer and improves electron mobility.

[0102] The specific embodiments described above have elaborated in detail the object, technical solution and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A phosphorescent host material, characterized in that, The phosphorescent host material has a compound structure shown in Formula 1 or Formula 2: ； Wherein, X is selected from O or S; R, R1, R2 are each independently selected from deuterium; The values of n are 0, 1, 2, 3, 4, 5, 6, 7, 8; The values of m and p are 0, 1, 2, 3, 4, 5; q takes the value 0, 1; Ar is unsubstituted or deuterium-substituted phenyl; Ar1 and Ar2 are independently selected from unsubstituted or deuterium-substituted C6-C 24 aryl, unsubstituted or deuterium-substituted C containing one heteroatom of O, S or N 12 -C 18 heteroaryl.

2. The phosphorescent host material according to claim 1, wherein The phosphorescent host material has any of the following structures: ； 。 3. A phosphorescent host material, characterized in that, The phosphorescent host material has a compound structure shown in Formula 1 or Formula 2: ； Wherein, X is selected from O or S; R, R1, R2 are each independently selected from deuterium; The values of n are 0, 1, 2, 3, 4, 5, 6, 7, 8; The values of m and p are 0, 1, 2, 3, 4, 5; q takes the value 0, 1; Ar is unsubstituted or deuterium-substituted phenyl; Ar1 and Ar2 are independently selected from the following groups which are unsubstituted or substituted with deuterium: wherein "*" represents the connection of the group to the carbon on the ring.

4. The phosphorescent host material according to claim 3, wherein The phosphorescent host material is selected from any one of the following compounds: ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； ； 。 5. A method for synthesizing the phosphorescent host material according to any one of claims 1 to 4, characterized in that, The following steps are involved: After reactant 1-a or reactant 2-a and reactant 1-b are dissolved in xylene, a palladium catalyst, a phosphorus ligand and a basic salt are added; Heat the reaction mixture to a temperature of 100-120°C and stir the mixture for 8-12h; After the reaction is completed, water and dichloromethane are added for extraction and separation, the organic phases are combined and concentrated, and a mixed solution of dichloromethane and petroleum ether is used for purification by column chromatography to obtain intermediate 1-c or 2-c; Dissolve intermediate 1-c or intermediate 2-c, reactant intermediate 1-d, palladium catalyst and potassium acetate in DMF, raise the temperature to 80-100° C., react for 6-8 hours, and remove the solvent using a rotary evaporator; The residue is added with dichloromethane, stirred, filtered, and purified by column chromatography to obtain intermediate 1-e or intermediate 2-e; Add intermediate 1-e or intermediate 2-e and reactant 1-f to a reaction flask, then add a mixed solution of toluene, ethanol and water, add a palladium catalyst and an alkaline salt, heat to 100-120° C., and reflux for 6-18 hours; Use diatomaceous earth to filter while hot, and after the filtrate is cooled to room temperature, water is added to the filtrate for washing, and after separation, the organic phase is retained, and the aqueous phase is extracted with ethyl acetate; Then, the combined organic layer is dried with magnesium sulfate, and purified by column chromatography to obtain a compound with a structure represented by Formula 1 or Formula 2; The reaction formula of the structural compound shown in the synthetic formula 1 is as follows: ； The reaction formula of the structural compound shown in the synthetic formula 2 is as follows: ； Wherein, Hal, Hal1, Hal2 are selected from F, Cl, Br or I; X is selected from O, or S; R, R1, R2 are each independently selected from deuterium; The values of n are 0, 1, 2, 3, 4, 5, 6, 7, 8; Both m and p are 0, 1, 2, 3, 4, 5; q takes the value of 0, 1; Ar is unsubstituted or deuterium-substituted phenyl; Ar1 and Ar2 are each independently selected from unsubstituted or deuterium-substituted C6-C 24 aryl, unsubstituted or deuterium-substituted C containing one heteroatom of O, S or N 12 -C 18 heteroaryl.

6. The synthesis method according to claim 5, wherein The alkaline salt is selected from one or more of potassium carbonate, potassium phosphate, sodium carbonate, cesium fluoride, cesium carbonate and sodium tert-butoxide; The palladium catalyst is selected from one or more of tris(dibenzylideneacetone)dipalladium, tetrakis(triphenylphosphine)palladium, palladium dichloride, [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride, palladium acetate, bis(triphenylphosphine)palladium dichloride and (1,1'-bis(diphenylphosphino)ferrocene)nickel dichloride; The phosphorus ligand is selected from one or more of tri-tert-butylphosphine, 2-cyclohexylphospho-2,4,6-triisopropylbiphenyl, triethylphosphine, trimethylphosphine, triphenylphosphine, potassium diphenylphosphine and di-tert-butylphosphine chloride.

7. An organic electroluminescent device, characterized in that, The organic electroluminescent device comprises an anode, a hole injection layer, a hole transport layer, a luminescence auxiliary layer, a luminescent layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode arranged in sequence; the luminescent layer contains the phosphorescent host material according to any one of claims 1 to 4.

8. The organic electroluminescent device according to claim 7, wherein The light emitting layer contains a phosphorescent host material as a first host compound, a second host compound, and a dopant material.

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