Phosphorescent host material, preparation method and organic electroluminescent device

Abstract

The invention belongs to the technical field of organic electroluminescent materials, and provides a phosphorescent host material, a preparation method and an organic electroluminescent device. The structural general formula of the phosphorescent host material is shown in the specification. The phosphorescent host material provided by the invention is applied to a luminescent device, and shows the characteristics of low driving voltage, high luminous efficiency and long service life, and the comprehensive performance of the device is excellent.

Description

Technical Field

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

[0002] Organic electroluminescent (OLED) devices have attracted much attention in the fields of new display technology and new lighting technology due to their advantages such as high brightness, fast response, wide viewing angle, simple process, and flexibility.

[0003] In order to continuously improve the performance of OLED devices, not only innovation in the structure and manufacturing process of organic electroluminescent devices is required, but also continuous research and innovation in organic functional materials. In recent years, although the design of phosphorescent host materials has gradually become diversified and the device lifetime or luminous efficiency has been improved, the comprehensive performance improvement of the device remains a major challenge, and a good balance cannot be achieved among the driving voltage, luminous efficiency, and lifetime. Therefore, developing a stable and efficient host material with excellent comprehensive device performance has important practical application value. Summary of the Invention

[0004] In view of this, 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 the characteristics of low driving voltage, high luminous efficiency, and long lifetime, and the device has excellent comprehensive performance.

[0005] To achieve the purpose of this invention, the following technical solutions are adopted:

[0006] In the first aspect, the present invention provides a phosphorescent host material with the following structural formula 1:

[0007]

[0008] Wherein,

[0009] X is selected from O or S;

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

[0011] n is 0, 1, 2, 3, 4, 5, 6, 7, 8;

[0012] m is 0, 1, 2;

[0013] p is 0, 1, 2, 3, 4, 5;

[0014] q is 0, 1;

[0015] Ar is an unsubstituted or deuterium-substituted phenyl group;

[0016] Ar1 and Ar2 are independently selected from unsubstituted or deuterium-substituted C6-C24 aryl groups, and unsubstituted or deuterium-substituted C12-C18 heteroaryl groups, the heteroatoms of which contain at least one of O, S, and N.

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

[0018]

[0019] Furthermore, q is 1.

[0020] Furthermore, Ar1 and Ar2 are independently selected from the following unsubstituted or deuterium-substituted groups:

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

[0022] It should be noted that 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] 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] In a second aspect, the present invention provides a method for preparing the phosphorescent host material as described above, specifically including the following steps:

[0040] Dissolve reactant 1-a (1.0 eq) and reactant 1-b (0.8 - 1.0 eq) in xylene, then add a palladium catalyst (0.01 - 0.05 eq), a phosphorus ligand (0.02 - 0.15 eq), and a base (2.0 - 2.4 eq); after addition, slowly raise the reaction temperature to 100 - 120 °C, and stir the mixture for 8 - 12 h; detect the reaction using thin-layer chromatography. After determining the end of the reaction, add water and dichloromethane for extraction and liquid separation. After combining the organic phases, concentrate them, and purify using a mixed solution of dichloromethane and petroleum ether (V:V = 1:4 - 1:8) by column chromatography to obtain intermediate 1-c.

[0041] Note: In this reaction step, there may be two halogens in raw material 1-a. On the one hand, utilize the characteristic of reaction activity I > Br > Cl, and on the other hand, control the reaction site by controlling the reaction conditions, and purify the reaction using column chromatography to obtain the target compound. Refer to the following common knowledge:

[0042] "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.

[0043] "Experimental Course of Organic Chemistry and Optoelectronic Materials", Chen Runfeng, Publisher: Southeast University Press, Publication Date: 2019 - 11 - 00, ISBN: 9787564184230, page 174.

[0044] Dissolve intermediate 1-c (1.0 eq), reactant 1-d (1.0 - 1.3 eq), a 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 - 10 h, and use a rotary evaporator to remove the solvent; add dichloromethane to the residue, stir and filter, and purify using column chromatography to obtain intermediate 1-e;

[0045] Add intermediate 1-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 base (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 Formula 1;

[0046] The specific synthesis route is as follows:

[0047]

[0048] Among them,

[0049] Hal, Hal1, Hal2 are selected from F, Cl, Br, I;

[0050] R, R1, R2, n, m, p, q, Ar, Ar1, and Ar2 have the definitions given above.

[0051] Furthermore, the base is selected from K2CO3 (potassium carbonate), K3PO4 (potassium phosphate), Na2CO3 (sodium carbonate), CsF (cesium fluoride), Cs2CO3 (cesium carbonate), or t-BuONa (sodium tert-butoxide); the palladium catalyst is selected from Pd2(dba)3 (bis(triphenylphosphine)palladium(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), or NiCl2(dppf) ((1,1'-bis(diphenylphosphino)ferrocene)nickel(II) chloride); the phosphine ligand is selected from P(t-Bu)3 (tri-tert-butylphosphine), X-phos (2-cyclohexylphosphino-2,4,6-triisopropylbiphenyl), PET3 (triethylphosphine), PMe3 (trimethylphosphine), PPh3 (triphenylphosphine), KPPh2 (potassium diphenylphosphide), or P(t-Bu)2Cl (di-tert-butylchlorophosphine).

[0052] In a third aspect, the present invention provides an organic electroluminescent device, which includes a first electrode, a second electrode, and an organic layer disposed between the first electrode and the second electrode; and,

[0053] The organic layer includes at least one or more of 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, and an electron injection layer; and,

[0054] The light-emitting layer contains the phosphorescent host material described above.

[0055] Furthermore, the light-emitting layer includes a host material and a doping material, and the host material contains the phosphorescent host material described above.

[0056] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0057] The present invention provides a parent nucleus structure in which the 1- and 2-positions of a dibenzo five-membered heterocycle are respectively substituted by a triazine group and a carbazole and its carbazole-derived group, and the aromatic ring on the unsubstituted side of the dibenzo five-membered heterocycle by the triazine is substituted by a phenyl group. The structure conforming to this general formula has strong rigidity due to the presence of ortho-substituted groups, enhanced structural stability due to reduced vibrational energy of the molecule, and weakened intermolecular interactions. Therefore, a thin film can be fabricated in an amorphous state, and the device lifetime can be improved. At the same time, the triplet state of the structure is relatively high, which can effectively prevent the triplet excited state energy level of the dopant from back-transferring to the triplet state energy level of the host, so as to obtain a high-efficiency device structure. Moreover, the phenyl group in the general formula is alone on one side, which can effectively utilize the conjugation of the phenyl group to make the carrier transport between molecules easier, reduce the driving voltage of the device, and improve the efficiency of the organic electroluminescent device. Description of the Drawings

[0058] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0059] Figure 1 1H NMR spectrum of compound 59 in Example 1 of the present invention. Detailed Embodiments

[0060] The following will clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0061] The embodiments of the present invention disclose and provide a phosphorescent host material and a preparation method thereof.

[0062] In addition, it should be noted that the values given in the following examples are as accurate as possible. However, those skilled in the art understand that due to inevitable measurement errors and experimental operation problems, each number should be understood as an approximate value rather than an absolutely accurate numerical value.

[0063] Example 1:

[0064]

[0065] After dissolving reactant 59-a (1.0 eq, CAS No.: 3033753-55-5) and reactant 59-b (0.8 eq, CAS No.: 88590-00-5) in xylene, 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, they were concentrated, and purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:4) to obtain intermediate 59-c.

[0066] Intermediate 59-c (1.0 eq), reactant 59-d (1.3 eq, CAS No.: 73183-34-3), Pd(PPh3)4 (0.01 eq), and potassium acetate (2.0 eq) were dissolved in DMF, heated to 90 °C, reacted for 8 h, and the solvent was removed using a rotary evaporator; the residue was added to dichloromethane, stirred, filtered, and purified by column chromatography to obtain intermediate 59-e;

[0067] Intermediate 59-e (1.0 eq) and reactant 59-f (1.3 eq, CAS No.: 3842-55-5) were added to a reaction flask, and then a mixed solution of toluene, ethanol, and water (volume ratio 3:1:1) was added. Pd(PPh3)4 (0.01 eq) and t-BuONa (2.0 eq) were added, heated to 120 °C, and refluxed for 10 h; filtration was carried out while hot using diatomaceous earth. After the filtrate was cooled to room temperature, water was added to the filtrate for washing. After liquid separation, the organic phase was retained, and the aqueous phase was extracted with ethyl acetate; then the combined organic layer was dried using magnesium sulfate and purified by column chromatography to obtain compound 59 (yield: 75.7%, measured value MS (ESI, m / z): [M + H]+ = 721.43).

[0068] The 1H NMR spectrum of compound 59 is as Figure 1 shown.

[0069] Characterization:

[0070] HPLC purity: >99.8%.

[0071] Elemental analysis:

[0072] Theoretical values: C, 84.86; H, 5.17; N, 7.76; O, 2.22

[0073] Measured values: C, 84.85; H, 5.22; N, 7.77; O, 2.26

[0074] Device Example 1: Preparation of green organic light-emitting device

[0075] a. ITO anode: The ITO (indium tin oxide)-Ag-ITO (indium tin oxide) glass substrate with a coating thickness of 150 nm was washed twice in distilled water, ultrasonically washed for 30 min, then repeatedly washed twice with distilled water, ultrasonically washed for 10 min, and baked in a vacuum oven at 220 °C for 2 hours. After baking, it can be used after cooling. Using this substrate as the anode, a vapor deposition device process was carried out using a vapor deposition machine, and other functional layers were vapor-deposited on it in sequence.

[0076] b. HIL (hole injection layer): At a vapor deposition rate of , the hole injection layer materials HT and P-dopant were vacuum vapor-deposited, and the vapor deposition rate ratio of HT and P-dopant was 97:3, with a thickness of 10 nm.

[0077] c. HTL (hole transport layer): At a vapor deposition rate of , 120 nm of HT was vacuum vapor-deposited on the hole injection layer as the hole transport layer.

[0078] d. Prime (luminescence assisting layer): At a vapor deposition rate of , 35 nm of Prime was vacuum vapor-deposited on the hole transport layer as the luminescence assisting layer.

[0079] e. EML (emitting layer): At a vapor deposition rate of , a total thickness of 40 nm of a double host material (Compound 59 provided by the present invention as the first host compound and Host-2 as the second host compound) and a doping material (Dopant) were vacuum vapor-deposited on the luminescence assisting layer as the emitting layer, where the vapor deposition rate ratio of the first host compound, the second host compound, and the doping compound was 46:46:8.

[0080] f. HB (hole blocking layer): At a vapor deposition rate of , a 5.0 nm thick HB hole blocking layer was vacuum vapor-deposited on the emitting layer.

[0081] g. ETL (electron transport layer): At a vapor deposition rate of For the evaporation rate, on the hole blocking layer, vacuum evaporate ET and Liq with a thickness of 30 nm as the electron transport layer, where the evaporation rate ratio of ET and Liq is 1:1.

[0082] h, EIL (electron injection layer): With the evaporation rate, on the electron transport layer, vacuum evaporate a 1.0 nm thick Yb film layer to form the electron injection layer.

[0083] i, cathode: With the evaporation rate, on the electron injection layer, vacuum evaporate 13 nm of magnesium and silver, and the evaporation rate ratio of magnesium and silver is 1:9 to obtain the cathode.

[0084] j, light extraction layer: With the evaporation rate, on the cathode, vacuum evaporate a 65 nm thick CPL as the light extraction layer.

[0085] k, Package the substrate after evaporation: First, use a gluing device to coat the cleaned cover plate with UV glue, then move the coated cover plate to the lamination section, place the substrate after evaporation on the upper end of the cover plate, and finally laminate the substrate and the cover plate under the action of a laminating device, and at the same time complete the light curing of the UV glue.

[0086] The material structures used in the above devices are as follows:

[0087]

[0088] Device Example 2 - Device Example 74:

[0089] Just replace the first host material in Device Examples 2 - 74 in Table 1 with Compound 59 in Device Example 1.

[0090] Device Comparative Example 1 - Device Comparative Example 24:

[0091] Referring to the preparation method provided in Device Example 1 above, replace Compound 59 in Device Example 1 with Comparative Compound 1 - Comparative Compound 24, and denote them as Device Comparative Example 1 - Device Comparative Example 24 respectively, where the chemical structural formulas of Comparative Compound 1 - Comparative Compound 24 are as follows:

[0092]

[0093]

[0094] Characterize the driving voltage, luminous efficiency, and lifetime of the organic electroluminescent devices obtained from Device Examples 1 - 74 and Device Comparative Examples 1 - 24 above at a brightness of 15000 (nits), and the test results are shown in Table 1 below.

[0095] Table 1 Device Test Results

[0096]

[0097]

[0098]

[0099]

[0100] As can be seen from Table 1, the organic electroluminescent device Examples 1-74 prepared using the luminescent layer host provided by the present invention have more excellent comprehensive performance compared with the devices prepared from Comparative Compounds 1-24.

[0101] Among them, Comparative Compound 1 and Compound 4 of the present invention are parallel comparative examples. The only difference between the two is the substitution position of 1-phenylcarbazolyl on dibenzofuran. The rigidities of both structures are relatively strong and there are ortho-substituted groups on the aromatic ring on one side of dibenzofuran. However, in the present invention, the phenyl group is alone on one side. Therefore, the conjugation of the phenyl group can be effectively utilized to make the intermolecular carrier transport easier, reduce the driving voltage of the device, and improve the efficiency of the organic electroluminescent device. Similarly, Comparative Compound 6 and Compound 43 of the present invention, Comparative Compound 22 and Compound 190 of the present invention, Comparative Compound 15 and Compound 185 of the present invention, Comparative Compound 23 and Compound 191 of the present invention, Comparative Compound 12 and Compound 172 of the present invention, Comparative Compounds 2, 3, and 4 and Compound 42 of the present invention are parallel comparative examples. The prior art all contains ortho-group enhanced structures to increase the steric and rigidities, but no other groups are bonded to the other side of dibenzofuran. Therefore, under the same device conditions, Compound 42 of the present invention exhibits a low driving voltage and relatively high luminous efficiency.

[0102] Compared with Compound 42 of the present invention, in addition to the different substitution positions of the triazine group and the carbazole group, the 3-position of the carbazole group in Comparative Compound 5 selects dibenzofuran for substitution, while in the present invention, phenyl is used for substitution. Since the electron-donating ability of dibenzofuran is stronger than that of phenyl, it makes Comparative Compound 5 less favorable for the hole and electron distribution in the luminescent layer compared with Compound 42 of the present invention, less favorable for improving the recombination efficiency of excitons in the luminescent layer, and less favorable for improving the overall performance of the device. Similarly, Comparative Compound 18 and Compound 186 of the present invention, Comparative Compound 19 and Compound 186 of the present invention.

[0103] Comparative compound 16 and compound 185 of the present invention are parallel comparative examples, and the difference lies only in the substitution position of the carbazole group, which conforms to the ortho-substitution mode of the general formula of the present invention. The steric hindrance is appropriately increased, the molecular structure is twisted, and the structural stability is enhanced. When applied in a device, it will improve the device life and increase the device efficiency. Similarly, comparative compound 7 and compound 55 of the present invention, comparative compound 8 and compound 85 of the present invention, comparative compound 9 and compound 86 of the present invention, comparative compound 10 and compound 169 of the present invention, comparative compound 11 and compound 172 of the present invention, comparative compound 13 and compound 178 of the present invention, comparative compound 21 and compound 189 of the present invention, comparative compound 24 and compound 192 of the present invention.

[0104] Comparative compound 14 and compound 185 of the present invention are parallel comparative examples. The difference lies only in the exchange of the substitution positions of the carbazole group and the triazine group. Generally, their structures are extremely similar, and the device performances when applied in the same device are also similar. However, it can be seen from the data in Table 1 that the connection mode conforming to the general formula of the present invention significantly improves the overall performance of the device. The reason is that in the current general formula structure, the 1-position of dibenzofuran is a triazine group with a large steric hindrance, and the 2-position is also substituted by a carbazole group. Therefore, compound 185 has greater steric hindrance than comparative compound 14, making the intermolecular interaction weaker, thereby reducing the crystallinity of the thin film and increasing the device life. Secondly, it is possible that the charge distribution in the present invention is more balanced than that of comparative compound 14, reducing the polarization degree of the material, increasing the mobility, and reducing the driving voltage. Similarly, comparative compound 20 and compound 187 of the present invention.

[0105] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A phosphorescent host material, characterized in that, The phosphorescent host material has a structure shown in Formula 1 below: Wherein, X is selected from O or S; R, R1, and R2 are independently selected from deuterium; n is 0, 1, 2, 3, 4, 5, 6, 7, 8; m is 0, 1, 2; p is 0, 1, 2, 3, 4, 5; q is 0, 1; Ar is an unsubstituted or deuterium-substituted phenyl group; Ar1 and Ar2 are independently selected from unsubstituted or deuterium-substituted C6-C24 aryl groups, unsubstituted or deuterium-substituted C12-C18 heteroaryl groups, and the heteroatoms thereof contain at least one of O, S, and N.

2. The phosphorescent host material according to claim 1, wherein The phosphorescent host material has any one of the following structures:

3. The phosphorescent host material according to claim 1 or 2, characterized in that, q is 1.

4. The phosphorescent host material according to claim 1 or 2, characterized in that, Ar1 and Ar2 are independently selected from unsubstituted or deuterium-substituted following groups: "*" represents the connection point of the group to the carbon on the ring.

5. The phosphorescent host material according to claim 4, wherein "Unsubstituted or deuterium-substituted" means that the group is substituted by one, two or more, up to the maximum number of substituents, of deuterium, or has no substituents.

6. The phosphorescent host material according to claim 1, characterized in that, The phosphorescent host material is selected from any one of the compounds shown in the following structural formulas:

7. A method for preparing the phosphorescent host material according to claim 1, characterized in that, The method specifically includes the following steps: After dissolving reactant 1-a (1.0 eq) and reactant 1-b (0.8 - 1.0 eq) in xylene, add palladium catalyst (0.01 - 0.05 eq), phosphorus ligand (0.02 - 0.15 eq), and base (2.0 - 2.4 eq); then slowly raise the reaction temperature to 100 - 120 °C, and stir the mixture for 8 - 12 h; detect the reaction by thin-layer chromatography. After determining the reaction is complete, add water and dichloromethane for extraction and liquid separation. After combining the organic phases and concentrating, use a mixed solution of dichloromethane and petroleum ether (V:V = 1:4 - 1:8) to purify through column chromatography to obtain intermediate 1-c; Dissolve intermediate 1-c (1.0 eq), reactant 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 - 10 h, and use a rotary evaporator to remove the solvent; add dichloromethane to the residue for stirring and filtration, and purify by column chromatography to obtain intermediate 1-e; Add intermediate 1-e (1.0 eq) and reactant 1-f (1.0 - 1.3 eq) into a reaction flask, then add a mixed solution of toluene, ethanol, and water (volume ratio 3:1:1), add palladium catalyst (0.01 - 0.02 eq), base (2.0 - 3.0 eq), raise the temperature to 100 - 120 °C, and reflux for 6 - 18 hours; filter while hot using diatomaceous earth. After the filtrate cools to room temperature, then 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 layers using magnesium sulfate and purify by column chromatography to obtain Formula 1; The specific synthesis route is as follows: Hal, Hal1, and Hal2 are selected from F, Cl, Br, I; R, R1, R2, n, m, p, q, Ar, Ar1, and Ar2 have the definitions as described in Claim 1.

8. The preparation method of the phosphorescent host material according to claim 7, wherein The base is selected from K2CO3 (potassium carbonate), K3PO4 (potassium phosphate), Na2CO3 (sodium carbonate), CsF (cesium fluoride), Cs2CO3 (cesium carbonate) or t-BuONa (sodium tert-butoxide); The palladium catalyst is selected from Pd2(dba)3 (bis(dibenzylideneacetone)palladium(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) or NiCl2(dppf) ((1,1'-bis(diphenylphosphino)ferrocene)nickel(II) chloride); The phosphine ligand is selected from P(t-Bu)3 (tri-tert-butylphosphine), X-phos (2-cyclohexylphosphino-2,4,6-triisopropylbiphenyl), PET3 (triethylphosphine), PMe3 (trimethylphosphine), PPh3 (triphenylphosphine), KPPh2 (potassium diphenylphosphate) or P(t-Bu)2Cl (di-tert-butylchlorophosphine).

9. An organic electroluminescent device, characterized in that, The organic electroluminescent device includes a first electrode, a second electrode, and an organic layer disposed between the first electrode and the second electrode; and, The organic layer includes one or more of 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, and an electron injection layer; and, The light-emitting layer contains the phosphorescent host material as described in Claim 1.

10. The organic electroluminescent device according to claim 9, characterized in that, The light-emitting layer includes a host material and a dopant material, and the host material contains the phosphorescent host material.

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