An organic blue light host material and its preparation method and application

Abstract

The present invention relates to the technical field of blue light electroluminescent materials, and discloses an organic blue light host material, a preparation method thereof, and an application thereof. The structural formula of the organic blue light host material is Formula I, wherein R1 to R8 are each independently selected from an H atom or an electron-donating / withdrawing structural unit. The organic blue light host material of the present invention uses dibenzothiophene as a core, introduces an electron-withdrawing or electron-deficient end group, and forms a D‑π‑A structure, which not only achieves good stability, high fluorescence efficiency, and an appropriate triplet energy level, but also promotes the injection and transport of electrons and holes, which is beneficial for its use as a light-emitting layer material in the preparation of non-doped organic electroluminescent devices, achieving low efficiency roll-off at high current density; at the same time, it can be used as the host of green / yellow / red phosphorescent materials to prepare phosphorescent electroluminescent devices with high efficiency and low roll-off.

Description

Technical Field

[0001] The present invention relates to the technical field of blue light electroluminescent materials, and in particular to an organic blue light host material and a preparation method and application thereof. Background Art

[0002] Organic light-emitting diodes (OLEDs), hailed as a "dream display" technology, offer advantages such as fast response, self-luminescence, wide viewing angles, and thin, flexible design. They demonstrate enormous application value in televisions, mobile phones, wearable devices, automotive displays, and lighting. The manufacturing of OLED display panels involves multiple processes, among which the three-primary-color organic electroluminescent materials represent one of the areas with the highest technical barriers. Currently, red and green light materials meet application requirements in terms of efficiency and stability. However, due to their inherent wide bandgap characteristics, the variety and quantity of blue light materials and their device performance lag behind. In particular, the lack of high-performance deep blue light materials and devices (meeting the standard blue light color coordinates (0.14, 0.08) established by the National Television Standards Committee (NTSC) of the United States) has become a key factor restricting the large-scale development of OLED technology in the high-definition and ultra-high-definition display industries.

[0003] Limited by the statistical rules of excitons, although traditional fluorescent and triplet-triplet annihilation (TTA) materials have good stability, the exciton utilization limit of the device is only 25% and 62.5%. The exciton utilization rate of phosphorescent and thermally activated delayed fluorescence (TADF) materials can reach 100%, but these two types of deep blue light materials usually have defects such as poor stability, high requirements on the energy level of the host material and large device efficiency roll-off, which makes it difficult to meet market demand. Doublet radical materials are limited by the stability of free radicals, making it difficult to construct blue and deep blue photoelectroluminescent materials. In comparison, the thermal exciton mechanism pioneered by Chinese scientists such as Academician Ma Yuguang uses high-energy triplet states (T n , n≥2) to the singlet state (S m , m ≥ 1) to increase the proportion of singlet excitons generated, theoretically achieving 100% exciton utilization. Blue organic light-emitting materials can act as emitters to achieve efficient blue emission, or as hosts for green / yellow / red phosphorescent materials to achieve energy transfer. In fact, in terms of molecular design, achieving both high-efficiency undoped OLEDs that meet the standard deep blue coordinates (0.14, 0.08) defined by the National Television Standards Committee (NTSC) of the United States and high-performance phosphorescent OLEDs is a huge challenge. Summary of the Invention

[0004] The present invention aims to overcome the shortcomings of the prior art by providing an organic blue light host material, its preparation method, and its application. The organic blue light host material of the present invention utilizes dibenzothiophene as a core and incorporates electron-withdrawing or electron-deficient end groups to form a D-π-A structure. This structure not only achieves good stability, high fluorescence efficiency, and an appropriate triplet energy level, but also promotes the injection and transport of electrons and holes, facilitating low efficiency roll-off in electroluminescent devices at high current densities. Furthermore, the material can serve as a host for green, yellow, or red phosphorescent materials, resulting in high-efficiency, low-roll-off phosphorescent electroluminescent devices.

[0005] In order to achieve the above-mentioned purpose, the technical solution of the present invention is: an organic blue light host material having a structure as shown in Formula I:

[0006]

[0007] In Formula I, R1 to R8 are each independently selected from an H atom or an electron donating / withdrawing structural unit, and the structural formula of the electron donating / withdrawing structural unit is selected from any one of the following:

[0008]

[0009]

[0010] Furthermore, the organic blue light host material has a structure shown in the following formula II, formula III or formula IV:

[0011]

[0012] A method for preparing an organic blue light host material comprises the following steps: dissolving 2-bromodibenzothiophene and 1-phenyl-2-(4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl)phenyl)-1H-phenanthro[9,10-d]imidazole in an organic solvent, then adding an alkaline solution and CH3CH2OH, reacting under the action of a catalytic system, and then post-processing to obtain a target product.

[0013] Furthermore, the organic solvent is toluene; the alkaline solution is a 2M potassium carbonate solution; the catalytic system is tetrakis(triphenylphosphine)palladium; the volume ratio of toluene, 2M potassium carbonate solution and CH3CH2OH is 2:1:1; the molar ratio of 2-bromodibenzothiophene, 1-phenyl-2-(4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl)phenyl)-1H-phenanthro[9,10-d]imidazole and tetrakis(triphenylphosphine)palladium is 2-3:2-3:0.1; the molar volume ratio of 2-bromodibenzothiophene to toluene is 2-3 mmol:20 mL; the reaction temperature is 110°C, the reaction time is 18 hours, and the post-treatment is to extract the reaction mixture with a mixture of CH2Cl2 and water, and then concentrate, separate and purify.

[0014] A method for preparing an organic blue light host material comprises the following steps:

[0015] (1) dissolving 2,8-dibromodibenzo[b,d]thiophene and 1-phenyl-2-(4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl)phenyl)-1H-phenanthro[9,10-d]imidazole in an organic solvent, then adding an alkaline solution and CH3CH2OH, reacting under the action of a catalyst system, and then post-treating to obtain 2-(4-(8-bromodibenzo[b,d]thiophen-2-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole;

[0016] (2) dissolving the 2-(4-(8-bromodibenzo[b,d]thiophen-2-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole prepared in step (1) and an aromatic boronic acid in a mixed solution of an organic solvent, an alkaline solution and CH3CH2OH, subjecting the mixture to a reflux reaction under the action of a catalytic system, and then post-processing to obtain the target product.

[0017] Furthermore, the organic solvent is toluene; the alkaline solution is a 2M potassium carbonate solution; the catalytic system is tetrakis(triphenylphosphine)palladium; the volume ratio of toluene, 2M potassium carbonate solution and CH3CH2OH is 2:1:1; and the aromatic boronic acid is (4-(trifluoromethyl)phenyl)boric acid or (4-(9h-carbazole-9-yl)phenyl)boric acid.

[0018] Furthermore, in step (1), the molar ratio of 2,8-dibromodibenzo[b,d]thiophene, 1-phenyl-2-(4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl)phenyl)-1H-phenanthrene[9,10-d]imidazole and tetrakis(triphenylphosphine)palladium is 25-35:25-35:1; the molar volume ratio of 2,8-dibromodibenzo[b,d]thiophene and toluene is 10-15mmol:30mL; the reaction temperature is 90°C, the reflux reaction time is 24 hours, and the post-treatment is to extract the reaction mixture with a mixture of CH2Cl2 and water, and then concentrate, separate and purify.

[0019] Furthermore, in step (2), the molar ratio of 2-(4-(8-bromodibenzo[b,d]thiophen-2-yl)phenyl)-1-phenyl-1H-phenanthrene[9,10-d]imidazole and aromatic boronic acid to tetrakis(triphenylphosphine)palladium is 25-35:25-35:1; the molar volume ratio of 2-(4-(8-bromodibenzo[b,d]thiophen-2-yl)phenyl)-1-phenyl-1H-phenanthrene[9,10-d]imidazole to toluene is 2-3 mmol:30 mL; the reaction temperature is 90° C., the reflux reaction time is 24 hours, and the post-treatment is to extract the reaction mixture with a mixture of CH2Cl2 and water, and then concentrate, separate and purify.

[0020] A use of the organic blue light host material according to claim 1 or 2 as a light-emitting layer material in an electroluminescent device, characterized in that the light-emitting layer material is a pure film containing molecules of the organic blue light host material.

[0021] A use of the organic blue light host material according to claim 1 or 2 as a host material in the light-emitting layer of a phosphorescent electroluminescent device, characterized in that the host material is a pure film or a mixed film containing molecules of the organic blue light host material.

[0022] Beneficial effects of the present invention:

[0023] (1) The organic blue light host material prepared by the present invention has a high synthesis yield, is simple to purify, and can be prepared in large quantities;

[0024] (2) The organic blue light host material prepared by the present invention has good solubility. Due to the introduction of different groups and the change in the spatial configuration of the entire molecule, the material can be dissolved in a variety of organic solvents, such as toluene, chloroform, chlorobenzene, etc., which is conducive to the formation of a uniform thin film by spin coating;

[0025] (3) The organic blue light host material prepared by the present invention has good film-forming properties and film morphology stability; due to the rigidity of dibenzothiophene and benzene rings, the material has good thermal stability, and the aromatic groups at the end groups have a large steric effect, which inhibits the aggregation of the material and thus promotes the performance and life of the device;

[0026] (4) The organic blue light host materials PPIS, PPISCF, and PPISPhCz prepared by the present invention were initially applied to non-doped devices to obtain deep blue light emitting devices with a power output of 1000 cd m -2 Previously, the external quantum efficiency (EQE) and current efficiency (CE) of the device increased with increasing brightness, with maximum EQEs of 6.68%, 5.08%, and 5.34%, respectively, and color coordinates of (0.156, 0.090), (0.154, 0.086), and (0.157, 0.077), respectively; using PPIS, PPISCF, and PPISPhCz as the host materials, the EQES of green, yellow, and red phosphorescent OLEDs reached 17.32% / 14.01% / 18.90%, 25.35% / 13.09% / 21.97%, and 22.19% / 10.18 / 23.52%, respectively, and showed a small efficiency roll-off. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the H NMR spectrum of the organic blue light host material PPIS prepared in Example 1;

[0028] Figure 2 This is the H NMR spectrum of the organic blue light host material PPISCF prepared in Example 2;

[0029] Figure 3 This is the H NMR spectrum of the organic blue light host material PPISPhCz prepared in Example 3;

[0030] Figure 4 This is the thermogravimetric curve of the organic blue light host material PPIS prepared in Example 1;

[0031] Figure 5 This is the thermogravimetric curve of the organic blue light host material PPISCF prepared in Example 2;

[0032] Figure 6 This is the thermogravimetric curve of the organic blue light host material PPISPhCz prepared in Example 3;

[0033] Figure 7 The differential scanning calorimetry curve of the organic blue light host material PPIS prepared in Example 1;

[0034] Figure 8The differential scanning calorimetry curves of the organic blue light host materials PPISCF and PPISPhCz prepared in Example 2 and Example 3;

[0035] Figure 9 Normalized absorption and photoluminescence spectra of the solution and film of the organic blue light host material PPIS prepared in Example 1;

[0036] Figure 10 Normalized absorption and photoluminescence spectra of the solutions and films of the organic blue light host materials PPISCF and PPISPhCz prepared in Examples 2 and 3;

[0037] Figure 11 This is the oxidation curve of the organic blue light host material PPIS prepared in Example 1;

[0038] Figure 12 Oxidation curves of the organic blue light host materials PPISCF and PPISPhCz prepared in Examples 2 and 3;

[0039] Figure 13 This is a graph showing the electroluminescent performance of a doped device containing the organic blue light host material PPIS prepared in Example 1 as a main component;

[0040] Figure 14 This is a graph showing the electroluminescent performance of a doped device containing the organic blue light host material PPISCF prepared in Example 2 as a main component;

[0041] Figure 15 This is a graph showing the electroluminescent performance of a doped device containing the organic blue light host material PPISPhCz prepared in Example 3;

[0042] Figure 16 This is the electroluminescent performance diagram of a non-doped device prepared with the organic blue light host material PPIS prepared in Example 1 as the light-emitting layer;

[0043] Figure 17 The electroluminescent performance diagram of the non-doped device prepared with the organic blue light host materials PPISCF and PPISPhCz prepared in Examples 2 and 3 as the light-emitting layer. DETAILED DESCRIPTION

[0044] The preparation of the organic blue light host material is further described below in conjunction with specific examples, but the scope of protection claimed by the present invention is not limited to the scope involved in the examples.

[0045] Example 1:

[0046] An organic blue light host material 2-(4-(dibenzothiophen-2-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole (PPIS) has the following structure:

[0047]

[0048] Preparation method of the PPIS:

[0049]

[0050] Under a nitrogen atmosphere, 2-bromodibenzothiophene (0.61 g, 2.32 mmol), 1-phenyl-2-(4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl)phenyl)-1H-phenanthro[9,10-d]imidazole (0.96 g, 2.84 mmol), and tetrakis(triphenylphosphine)palladium (0.12 g, 0.1 mmol) were dissolved in toluene (20 mL). CH3CH2OH (10 mL) and 2 M potassium carbonate solution (10 mL) were added, and the mixture was stirred at 110°C for 18 hours. After the reaction, the mixture was cooled to room temperature and extracted with a mixture of CH2Cl2 and water. The organic layer was evaporated on a rotary evaporator, and the crude product was further purified by silica gel column chromatography with CH2Cl2 as the eluent. Finally, the product PPIS (1 g, yield: 94%) was obtained by vacuum drying as a white solid. 1 H NMR (400MHz, CDCl3) δ (ppm): 8.95 (d, J = 8.0Hz, 1H), 8.78 (dd, J = 8.5, 1.2Hz, 1H), 8.74–8.68 (m, 1H), 8.33 (d, J = 1.7Hz, 1H), 8.23–8.19 (m, 1H), 7.91–7. 85(m,2H),7.79–7.71(m,3H),7.67(ddd,J=8.5,7.1,2.8Hz,7H),7.61–7.56 (m,2H),7.55–7.46(m,3H),7.31–7.26(m,1H),7.20(dd,J=8.4,1.4Hz,1H). 13C NMR(101MHz, CDCl3)δ(ppm):150.41,141.45,139.93,138.93,138.75,136 .85,136.15,135.47,130.32,129.98,129.89,129.37,129.19,128.36,12 8.23,127.39,127.07,126.96,126.34,125.94,125.78,125.01,124.50,1 24.16,123.14,123.10,122.95,121.67,120.90,119.89.TOF-MS(ESI)m / z calcd.for C39H24N2S:552.1660;[M+H]+found:552.6360.

[0051] Example 2:

[0052] An organic blue light host material 1-phenyl-2-(4-(4-(trifluoromethylphenyl)dibenzo[b,d]thiophen-2-yl)phenyl)-1H-phenanthro[9,10-d]imidazole (PPISCF) has the following structure:

[0053]

[0054] The preparation method of the PPISCF comprises the following steps:

[0055]

[0056]

[0057] (1) 2,8-Dibromodibenzo[b,d]thiophene (4 g, 11.70 mmol), 1-phenyl-2-(4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl)phenyl)-1H-phenanthro[9,10-d]imidazole (6.39 g, 12.87 mmol) and tetrakis(triphenylphosphine)palladium (0.47 g, 0.41 mmol) were placed in a 250 mL two-necked flask and nitrogen was replaced three times. Then, toluene (30 mL), 2 M potassium carbonate (15 mL) and CH3CH2 were added to the two-necked flask. OH (15 mL), the temperature was controlled at 90 ° C, and the mixture was refluxed under stirring for 24 hours. After cooling to room temperature, the reaction mixture was extracted with a mixture of CH2Cl2 and water, and the organic layer was evaporated under reduced pressure on a rotary evaporator. The intermediate product was further separated and purified by silica gel column chromatography using petroleum / dichloromethane (1 / 1) as eluent; finally, vacuum drying gave 2-(4-(8-bromodibenzo[b,d]thiophen-2-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole (4.31 g, yield 39%) as a white solid. 1 H NMR (400MHz, CDCl3) δ (ppm): 8.96 (d, J = 7.9Hz, 1H), 8.78 (d, J = 8.3Hz, 1H), 8.71 (d, J = 8.3Hz, 1H), 8.32 (d, J = 1.9Hz, 1 H),8.26(d,J=1.8Hz,1H),7.88(d,J=8.4Hz,1H),7.80–7.49(m,15H),7.32–7.27(m,1H),7.19(dd,J=8.4,1.3Hz,1H);

[0058] (2) Under nitrogen atmosphere, 2-(4-(8-bromodibenzo[b,d]thiophen-2-yl)phenyl)-1-phenyl-1H-phenanthrene[9,10-d]imidazole (1.5 g, 2.38 mmol), (4-(fluoromethyl)phenyl)boric acid (0.50 g, 2.62 mmol) and tetrakis(triphenylphosphine)palladium (0.096 g, 0.08 mmol) prepared in step (1) were placed in a 250 mL two-necked flask. Then, toluene was added to the two-necked flask. Benzene (30 mL), 2 M potassium carbonate (15 mL) and CH3CH2OH (15 mL) were refluxed under stirring at 90°C for 24 hours. After cooling to room temperature, the mixture was extracted with a mixture of CH2Cl2 and water. The organic layer was evaporated under reduced pressure on a rotary evaporator. The intermediate product was further separated and purified by silica gel column chromatography using petroleum / dichloromethane (1 / 1) as eluent and dried in vacuo to give PPISCF (1.18 g, 39% yield) as a white solid. 1HNMR (400MHz, CDCl3) δ (ppm): 8.99 (d, J = 7.8Hz, 1H), 8.77 (d, J = 8.4Hz, 1H), 8.70 (d, J = 8.3Hz, 1H), 8.38 (t, J = 2.4Hz, 2H), 7.92 (dd, J=16.2,8.3Hz,2H),7.83(d,J=8.1Hz,2H),7.79–7.57(m,15H),7.52(t,J=7.9Hz,1H),7.29(d,J=7.8Hz,1H),7.18(d,J=8.2Hz,1H). 13 C NMR (101MHz, CDCl3) δ (ppm): 144.60, 139.97, 139.42, 137.11, 136.52, 136.1 6,135.93,130.32,129.98,129.92,129.38,129.19,128.36,128.26,127.67 ,127.39,127.06,126.34,126.23,125.89,125.85,125.03,124.16,123.44, 123.28,123.14,122.93,120.89,120.28,119.95.TOF-MS(ESI)m / zcalcd.for C46H27F3N2S:696.1847;[M+H]+found:697.1930.

[0059] Example 3:

[0060] An organic blue light host material 1-phenyl-2-(4-(4a, 4b, 8a, 9a-tetrahydro-9H-carbazole-9-yl)phenyl)dibenzo[b, d]thiophen-2-yl)phenyl)-1H-phenanthro[9, 10-d]imidazole (PPISPhCz) has the following structure:

[0061]

[0062] The preparation method of the PPISPhCz comprises the following steps:

[0063]

[0064] (1) Prepare 2-(4-(8-bromodibenzo[b,d]thiophen-2-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole by the same method as in step (1) of Example 2;

[0065] (2) Under a nitrogen atmosphere, 2-(4-(8-bromodibenzo[b,d]thiophen-2-yl)phenyl)-1-phenyl-1H-phenanthrene[9,10-d]imidazole (1.5 g, 2.38 mmol) prepared in step (1), (4-(9h-carbazol-9-yl)phenyl)boric acid (0.752 g, 2.62 mmol) and tetrakis(triphenylphosphine)palladium (0.096 g, 0.08 mmol) were respectively placed in a 250 mL two-necked flask. Then, toluene (30 mL), 2M potassium carbonate (15 mL) and CH3CH2OH (15 mL) were added to the two-necked flask. The temperature was controlled at 90°C. Under stirring, the mixture was refluxed for reaction for 24 hours. After cooling to room temperature, it was extracted with a mixture of CH2Cl2 and water, and the organic layer was evaporated under reduced pressure using a rotary evaporator. The intermediate product was further separated and purified by silica gel column chromatography using petroleum / dichloromethane (1 / 1) as eluent and dried in vacuo to give PPISPhCz (1.31 g, yield 69%) as a white solid. 1 H NMR (400MHz, CDCl3) δ (ppm): 8.98 (d, J = 7.9Hz, 1H), 8.77 (d, J = 8.3Hz, 1H), 8.70 (d, J = 8.3Hz, 1H), 8.49 (d, J = 1.8Hz, 1H), 8.43 (d, J = 1.8Hz, 1H), 8.17 ( dd,J=7.8,1.1Hz,2H),8.00–7.90(m,4H),7.85–7.62(m,13H),7.62–7.56( m,2H),7.55–7.42(m,5H),7.38–7.26(m,3H),7.18(dd,J=8.4,1.3Hz,1H). 13 CNMR(101MHz, CDCl3)δ(ppm):141.33,140.90,140.18,139.49,139.39,138.72,137.13,137.0 1,136.99,136.19,136.09,130.33,130.00,129.95,129.39,129.19,128.80,128.37,128.23,1 27.51,127.42,127.07,126.36,126.27,126.23,126.03,125.82,125.06,124.16,123.49,123. 40,123.30,123.14,122.94,120.89,120.39,120.16,120.05,119.96,109.86.TOF-MS(ESI)m / z calcd.for C57H39N3S:798.0200;[M]+found:797.2675.

[0066] The performance tests were performed on the organic blue light host materials PPIS, PPISCF, and PPISPhCz prepared in Examples 1-3 respectively:

[0067] (1) H NMR spectrum:

[0068] Figure 1 This is the H NMR spectrum of the organic blue light host material PPIS prepared in Example 1;

[0069] Figure 2 This is the H NMR spectrum of the organic blue light host material PPISCF prepared in Example 2;

[0070] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of the organic blue light host material PPISPhCz prepared in Example 3.

[0071] (2) Thermodynamic properties:

[0072] Figure 4 This is the thermogravimetric curve of the organic blue light host material PPIS prepared in Example 1;

[0073] Figure 5 This is the thermogravimetric curve of the organic blue light host material PPISCF prepared in Example 2;

[0074] Figure 6 This is the thermogravimetric curve of the organic blue light host material PPISPhCz prepared in Example 3;

[0075] Figure 7 The differential scanning calorimetry curve of the organic blue light host material PPIS prepared in Example 1;

[0076] Figure 8 These are the differential scanning calorimetry curves of the organic blue light host materials PPISCF and PPISPhCz prepared in Example 2 and Example 3.

[0077] The thermogravimetric curves show that the PPIS, PPISCF and PPISPhCz prepared in Examples 1-3 all have good thermal stability and can be applied to thermal evaporation OLEDs devices (T d >400℃).

[0078] (3) Photophysical properties:

[0079] Figure 9 The organic blue light host material PPIS prepared in Example 1 was dissolved in toluene (~1.0×10 -5 mol L -1 ) and normalized absorption and photoluminescence spectra of thin films on quartz glass;

[0080] Figure 10 The organic blue light host materials PPISCF and PPISPhCz prepared in Example 2 and Example 3 were dissolved in toluene (~1.0×10 -5 mol L -1 ) and normalized absorption and photoluminescence spectra of thin films on quartz glass.

[0081] The emission peaks of the organic blue light host materials PPIS, PPISCF, and PPISPhCz films are 431nm, 437nm, and 437nm, respectively, which are deep blue light emissions and help to obtain deep blue light devices.

[0082] (4) Electrochemical performance:

[0083] Figure 11 This is the oxidation curve of the organic blue light host material PPIS prepared in Example 1;

[0084] Figure 12 These are the oxidation curves of the organic blue light host materials PPISCF and PPISPhCz prepared in Example 2 and Example 3.

[0085] (5) Performance of organic electroluminescent devices:

[0086] The device performance tests are performed on the organic blue light host materials PPIS, PPISCF and PPISPhCz prepared in Example 1, Example 2 and Example 3.

[0087] PPIS was used as the organic host material in a vacuum evaporation method to fabricate a doped organic electroluminescent device. The specific device structure is: ITO / HATCN (20nm) / TAPC (50nm) / TCTA (5nm) / PPIS:8% dopant (20nm) / TPBi (40nm) / LiF (1nm) / Al. The dopant is iridium (III) (Ir(ppy)2acac).

[0088] PPISCF was used as the organic host material in a doped organic electroluminescent device fabricated by vacuum evaporation. The device structure was: ITO / HATCN (20 nm) / TAPC (50 nm) / TCTA (5 nm) / PPISCF:8% dopant (20 nm) / TPBi (40 nm) / LiF (1 nm) / Al. The dopant was iridium(III) (4-phenylthiophene[3,2-c]pyridine-N,C2') acetylacetonate (PO-01).

[0089] PPISPhCz was used as the organic host material in a doped organic electroluminescent device fabricated by vacuum evaporation. The device structure was: ITO / HATCN (20 nm) / TAPC (50 nm) / TCTA (5 nm) / PPISPhCz:5% dopant (20 nm) / TPBi (40 nm) / LiF (1 nm) / Al. The dopant was iridium(III) (2-methyldibenzo-[f,h]quinoline) (acetylacetone) (Ir(MDQ)2acac).

[0090] PPIS is used as the light-emitting layer material, and a non-doped organic electroluminescent device is prepared by vacuum evaporation. The specific device structure is: ITO / HATCN (20nm) / TAPC (50nm) / TCTA (5nm) / PPIS (20nm) / TPBi (40nm) / LiF (1nm) / Al.

[0091] PPISCF was used as the light-emitting layer material, and a non-doped organic electroluminescent device was prepared by spin coating and vacuum evaporation. The specific device structure was: ITO / PEDOT:PSS (30nm) / TCTA (20nm) / PPISCF (20nm) / TPBi (25nm) / LiF (1nm) / Al.

[0092] PPISPhCz was used as the light-emitting layer material, and a non-doped organic electroluminescent device was prepared by spin coating and vacuum evaporation. The specific device structure was: ITO / PEDOT:PSS (30nm) / TCTA (20nm) / PPISPhCz (20nm) / TPBi (25nm) / LiF (1nm) / Al.

[0093] The specific molecular structures of the above materials are as follows:

[0094]

[0095] Figure 13 This is a graph showing the electroluminescent performance of a doped device containing the organic blue light host material PPIS prepared in Example 1 as a main component;

[0096] Figure 14 This is a graph showing the electroluminescent performance of a doped device containing the organic blue light host material PPISCF prepared in Example 2 as a main component;

[0097] Figure 15 This is a diagram of the electroluminescent performance of the doped device with the organic blue light host material PPISPhCz prepared in Example 3 as the main body.

[0098] pass Figure 13-15It can be seen that the three materials have achieved good results as the main body of phosphorescent materials, and the efficiency of green, yellow and red light has reached a high level, indicating their excellence as the main body materials.

[0099] Figure 16 This is the electroluminescent performance diagram of a non-doped device prepared with the organic blue light host material PPIS prepared in Example 1 as the light-emitting layer;

[0100] Figure 17 The electroluminescent performance diagram of the non-doped device prepared with the organic blue light host materials PPISCF and PPISPhCz prepared in Examples 2 and 3 as the light-emitting layer.

[0101] pass Figure 16-17 It can be seen that the three materials have achieved good results in electroluminescent devices when used as light-emitting layer materials, and the external quantum efficiency has reached a high level, indicating their excellence as light-emitting layer materials.

[0102] Table 1 shows the specific device performance test data. GD, YD, and RD represent green, yellow, and red light-emitting devices with PPIS as the organic host material, respectively; GD1, YD1, and RD1 represent green, yellow, and red light-emitting devices with PPISCF as the organic host material, respectively; GD2, YD2, and RD2 represent green, yellow, and red light-emitting devices with PPISPhCz as the organic host material, respectively; and BD, BD1, and BD2 represent electroluminescent devices with PPIS, PPISCF, and PPISPhCz as the emissive layer materials, respectively.

[0103] Table 1

[0104]

[0105] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. An organic blue light host material, characterized by: Having a structure as shown in Formula III or Formula IV: Formula III Formula IV.

2. A method for preparing the organic blue light host material according to claim 1, characterized in that: The steps include: (1) 2,8-dibromodibenzo[b,d]thiophene and 1-phenyl-2-(4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl)phenyl)-1H-phenanthro[9,10-d]imidazole are dissolved in an organic solvent, and then an alkaline solution and CH3CH2OH are added to react under the action of a catalytic system, and then post-treated to obtain 2-(4-(8-bromodibenzo[b,d]thiophen-2-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole; (2) The 2-(4-(8-bromodibenzo[b,d]thiophen-2-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole prepared in step (1) and an aromatic boronic acid are dissolved in a mixed solution of an organic solvent, an alkaline solution and CH3CH2OH, refluxed under the action of a catalytic system, and then post-treated to obtain the target product, wherein the aromatic boronic acid is (4-(trifluoromethyl)phenyl)boric acid or (4-(9h-carbazol-9-yl)phenyl)boric acid.

3. The method for preparing an organic blue light host material according to claim 2, wherein: The organic solvent is toluene; the alkaline solution is a 2M potassium carbonate solution; the catalytic system is tetrakis(triphenylphosphine)palladium; and the volume ratio of toluene, 2M potassium carbonate solution and CH3CH2OH is 2:1:

1.

4. The method for preparing an organic blue light host material according to claim 3, wherein: The molar ratio of 2,8-dibromodibenzo[b,d]thiophene, 1-phenyl-2-(4,4,5,5-tetramethyl-1,3,2-dioxaboran-2-yl)phenyl)-1H-phenanthro[9,10-d]imidazole and tetrakis(triphenylphosphine)palladium in step (1) is 25-35:25-35:1; the molar volume ratio of 2,8-dibromodibenzo[b,d]thiophene and toluene is 10-15 mmol:30 mL; the reaction temperature is 90° C., the reflux reaction time is 24 hours, and the post-treatment is to extract the reaction mixture with a mixture of CH2Cl2 and water, and then concentrate, separate and purify.

5. The method for preparing an organic blue light host material according to claim 3, wherein: In step (2), the molar ratio of 2-(4-(8-bromodibenzo[b,d]thiophen-2-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole and aromatic boronic acid to tetrakis(triphenylphosphine)palladium is 25-35:25-35:1; the molar volume ratio of 2-(4-(8-bromodibenzo[b,d]thiophen-2-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]imidazole to toluene is 2-3 mmol:30 mL; the reaction temperature is 90° C., the reflux reaction time is 24 hours, and the post-treatment is to extract the reaction mixture with a mixture of CH2Cl2 and water, and then concentrate, separate and purify.

6. Use of the organic blue light host material according to claim 1 as a light-emitting layer material in an electroluminescent device, characterized in that: The light-emitting layer material is a pure film containing molecules of the organic blue light host material.

7. Use of the organic blue light host material according to claim 1 as a host material in a light-emitting layer of a phosphorescent electroluminescent device, characterized in that: The host material is a pure film or a mixed film containing the organic blue light host material molecules.

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