An organic compound for a blue light device and a blue light organic electroluminescent device

Abstract

The application belongs to the technical field of OLED and specifically comprises an organic compound for a blue light device and a blue light organic electroluminescent device. The structural general formula of the organic compound is shown in the following. The application directly connects a benzofuranphenanthrol group to the 12th position of a benzanthracene nucleus, which can utilize the oxygen atom on the furan to increase the polarity and intermolecular interaction of the molecule, improve the molecular orientation when the material is stacked, thereby strengthen the permanent spontaneous orientation polarization effect, and obtain a better voltage improvement effect; on the other hand, the direct connection of the phenanthrene ring on the benzofuranphenanthrol group to the 12th position of the benzanthracene can improve the electron mobility of the material, thereby improving the electron density in the light-emitting layer, and with the increase of the electron density, the carrier recombination probability can be significantly improved, thereby reducing the accumulation of holes in the light-emitting layer, reducing the exciton quenching condition, and improving the device efficiency.I.

Description

Technical Field

[0001] This invention belongs to the field of OLED technology, specifically including an organic compound for blue light devices and a blue light organic electroluminescent device. Background Technology

[0002] In recent years, to improve the performance of blue OLED devices, a dual-emitting-layer (DEL) architecture has been proposed. This architecture employs two adjacent emitting layers with different dominant triplet energy levels. Utilizing dexter energy transfer, it separates the carrier recombination process and triplet-triplet fusion process, which traditionally occur in a single emitting layer, into two adjacent EDL layers. This significantly reduces the quenching of carriers and excitons, and singlet and triplet excitons, resulting in a substantial increase in efficiency. However, existing DEL blue OLED systems still have significant technical limitations, restricting further improvements in device performance.

[0003] First, benzenexane is an excellent host material for blue fluorescence due to its energy level matching, but its molecular skeleton has an asymmetric L-shaped structure. When a substituent is introduced at the 12-position of benzenexane, the substituent cannot be coplanar with the host nucleus due to the steric hindrance of the hydrogen atom at the 1-position, which introduces a large steric hindrance. This results in disordered molecular orientation and a weak permanent spontaneous orientation polarization effect, making it difficult to further reduce the operating voltage of the device.

[0004] Secondly, in dual-emitting-layer devices, the first emitting layer is mainly responsible for carrier recombination, but the migration and accumulation characteristics of holes in this layer are better than those of electrons, easily leading to hole enrichment. Accumulated holes can trigger exciton quenching, significantly reducing the device's luminous efficiency. Existing technologies cannot effectively solve the problem of hole accumulation in the first emitting layer, severely restricting the improvement of device efficiency.

[0005] In summary, existing dual-emitting-layer blue OLEDs suffer from problems such as poor molecular orientation, insufficient polarization performance, high operating voltage, and hole-induced exciton quenching, which urgently require new material design and device optimization solutions. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, the present invention provides an organic compound for blue light devices and a blue light organic electroluminescent device.

[0007] To achieve the above objectives, the technical solution adopted by the present invention includes: A first aspect of the present invention provides an organic compound for use in blue light devices, the organic compound having the following general structural formula: I; R1 is selected from one of the following structures: , , , , , , ; R2 is selected from any one of phenyl, naphthyl, phenanthryl, and biphenyl; In Formula I, any hydrogen atom can be replaced by deuterium.

[0008] In this invention, when the phenanthrene fragment of benzofuran-phenanthrene is directly connected to the benzanthracene core, this special structural design has the following considerations: When at least one side of the benzanthracene core is a sterically hindered substituent, this invention can further avoid both sides of the benzanthracene having a highly sterically hindered structure, thus avoiding the generation of isomers due to the inability of the sterically hindered groups to rotate freely. This is because both sides having highly sterically hindered α-naphthyl groups cannot rotate freely to generate isomers. Furthermore, when at least one side of the benzanthracene core is a highly sterically hindered substituent, it can suppress molecular vibrational relaxation and improve the quantum luminescence efficiency of the material. Even further, when R1 avoids using highly sterically hindered aryl fragments, it can further avoid the generation of coupling impurities with the core, thereby further improving the stability of the material.

[0009] Furthermore, R1 is selected from one of the following structures: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , .

[0010] Furthermore, when R1 is selected from the above-mentioned groups, R2 is selected from one of the following structures: , , , , , .

[0011] Furthermore, R1 is selected from one of the following structures: , , , , , , , , , , , , , , , .

[0012] Furthermore, when R1 is selected from one of the following structures: , , , , , , , , , , , , , , , R2 is selected from one of the following structures: , , , .

[0013] Furthermore, the organic compound is selected from one of the following structures: I-1 I-2; Wherein, the R 11 Selected from Any one of them.

[0014] Furthermore, the organic compound is selected from one of the following structures:

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[0058] A second aspect of the present invention provides a blue organic light-emitting device, the blue organic light-emitting device comprising an anode, a hole transport region, a light-emitting layer, an electron transport region and a cathode sequentially disposed on a substrate; wherein the light-emitting layer comprises an organic compound as described above.

[0059] Furthermore, the light-emitting layer comprises a host material and a dopant material, wherein the host material is selected from the organic compounds described above.

[0060] A third aspect of the present invention provides a dual-emitting-layer blue organic electroluminescent device, the dual-emitting-layer blue organic electroluminescent device comprising an anode, a hole transport region, a first emitting layer, a second emitting layer, an electron transport region and a cathode sequentially disposed on a substrate; wherein the first emitting layer comprises the organic compound described above.

[0061] Furthermore, the first light-emitting layer includes a first host material and a dopant material, wherein the first host material is selected from the organic compounds described above.

[0062] Beneficial effects of this invention: This invention provides an organic compound for blue light-emitting devices. By introducing a benzofuran-phenanthrene fragment into the benzofuran-phenanthrene core, and by defining the connection between the phenanthrene ring in the benzofuran-phenanthrene fragment and the 12th position of the benzofuran-phenanthrene group (i.e., the R1 substitution site in Formula I), this invention can, on the one hand, utilize the oxygen atom on the furan to increase molecular polarity and intermolecular interactions, improve molecular orientation during material stacking, thereby enhancing the permanent spontaneous orientation polarization effect and achieving better voltage improvement; on the other hand, the direct connection between the phenanthrene ring on the benzofuran-phenanthrene group and the 12th position of the benzofuran-phenanthrene group can improve the electron mobility of the material, thereby increasing the electron density in the emitting layer. With the increase in electron density, the carrier recombination probability can be significantly increased, thereby reducing the accumulation of holes in the emitting layer, reducing exciton quenching, and improving device efficiency.

[0063] Furthermore, by defining the structure of R1 and R2, the present invention ensures that at least one side of the benzenex anthracene core is a substituent with low steric hindrance, thus avoiding the formation of isomers due to the inability of steric hindrance groups to rotate freely. Furthermore, by defining the structures of R1 and R2, the present invention enables at least one side of the benzanthracene core to be a sterically hindered substituent, which can suppress molecular vibrational relaxation and improve the quantum luminescence efficiency of the material. Moreover, by defining R1 as a sterically hindered substituent and R2 as a sterically hindered aryl fragment, the present invention can further avoid the generation of coupling impurities with the core, thereby further improving the stability of the material. Attached Figure Description

[0064] Figure 1 This is a schematic diagram of the structure of the organic electroluminescent device of the present invention, wherein 1-substrate, 2-anode, 3-hole injection layer, 4-hole transport layer, 5-electron blocking layer, 6-first light-emitting layer, 7-second light-emitting layer, 8-hole blocking layer, 9-electron transport layer, 10-electron injection layer, 11-cathode, and 12-capping layer. Detailed Implementation

[0065] To better understand the content of this invention, it will be described in detail with reference to the accompanying drawings and embodiments.

[0066] The compounds of this invention are applicable to light-emitting elements, display panels, and electronic devices, particularly organic electroluminescent devices. The electronic devices described in this invention are devices comprising a layer of at least one organic compound, and may also comprise layers of inorganic materials or layers formed entirely of inorganic materials. Preferably, the electronic devices are organic electroluminescent devices (OLEDs), organic integrated circuits (O-ICs), organic field-effect transistors (O-FETs), organic thin-film transistors (O-TFTs), organic light-emitting transistors (O-LETs), organic solar cells (O-SCs), organic dye-sensitized solar cells (O-DSSCs), organic optical detectors, organic photosensors, organic field quenching devices (O-FQDs), light-emitting electrochemical cells (LECs), organic laser diodes (O-lasers), and organic plasma emitting devices. Organic electroluminescent devices (OLEDs) are particularly preferred. A schematic diagram of an exemplary organic electroluminescent device is shown below. Figure 1 As shown.

[0067] Experimental Section To better understand the content of this invention, the polycyclic compound, the preparation method of the compound, and the luminescent properties of the device will be explained in detail with reference to embodiments. Various chemical reactions can be applied to the synthesis method of the compound according to one embodiment of this invention. However, it should be noted that the synthesis method of the compound according to one embodiment of this invention is not limited to the synthesis method described below. Unless otherwise stated, subsequent synthesis is carried out in an anhydrous solvent under a protective gas atmosphere. Solvents and reagents can be purchased from conventional reagent suppliers.

[0068] intermediate synthesis

[0069] In a 500 mL three-necked flask, under nitrogen protection, 125 mL of toluene, 80 mL of ethanol, and 80 mL of water were added. Then, compound H2 (7.68 g, 25 mmol), substrate compound K2 (3.05 g, 25 mmol), potassium carbonate (10.38 g, 75 mmol), and tetrakis(triphenylphosphine)palladium (0.88 g, 0.75 mmol) were added. The mixture was heated to 80 °C and reacted for 12 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, and the filter cake was dissolved in toluene and filtered to remove the solid insoluble matter. The mixture was then recrystallized to give intermediate compound L2: 6.46 g, yield: 85%, MS (m / z) (M+): 304.

[0070] Other intermediate compounds LX can be prepared by referring to the preparation method of intermediate compound L2 described above, simply by replacing substrate compound K2 with the corresponding substrate compound KX.

[0071] In a 500 mL three-necked flask, intermediate compound L2 (6.08 g, 20 mmol) was stirred with 200 mL of N,N-dimethylformamide. N-bromosuccinimide (4.28 g, 24 mmol) was added at room temperature, and the mixture was stirred for 8 hours. Methanol was added to the reaction solution, and the resulting yellow solid was filtered. The solid was recrystallized from toluene and dried under vacuum to give compound A-2: 5.75 g, yield: 75%, MS (m / z) (M+): 383.

[0072] Other compounds AX can be obtained by replacing the LX intermediate.

[0073] Synthesis Example 1

[0074] In a 250 mL three-necked flask, under nitrogen protection, 50 mL of toluene, 25 mL of ethanol, and 25 mL of water were added. Then, compound A-1 (3.83 g, 10 mmol), compound B-1 (3.12 g, 10 mmol), potassium carbonate (4.15 g, 30 mmol), and tetraphenylphosphine palladium (0.35 g, 0.3 mmol) were added. The mixture was heated to 80 °C and reacted for 12 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, and the filter cake was dissolved in toluene and filtered to remove the solid insoluble matter. The product C-1 was then recrystallized to give product C-1: 4.11 g, yield: 72%, MS (m / z) (M+): 570. 1 HNMR (500 MHz, DMSO- d 6) δ 8.49 – 8.44 (m, 1H), 8.25 – 8.17 (m, 3H), 8.04 –7.96 (m, 3H), 7.93 – 7.84 (m, 4H), 7.76 (d, J = 8.1 Hz, 1H), 7.67 – 7.62 (m,1H), 7.59 – 7.45 (m, 11H), 7.42 – 7.32 (m, 2H). Synthesis Example 2

[0075] The preparation method was the same as in Example 1, except that compounds A-2 (3.83 g; 10 mmol) and B-2 (3.12 g; 10 mmol) were used to replace compounds A-1 and B-1, and the final product C-2 was obtained: 3.83 g, yield: 67%, MS (m / z) (M+): 570.

[0076] Synthesis Example 3

[0077] The preparation method was the same as in Example 1, except that compounds A-1 and B-1 were replaced with compounds A-3 (4.4 g; 10 mmol) and B-3 (3.12 g; 10 mmol), and the final product C-3 was 5.02 g, yield: 80%, MS (m / z) (M+): 627.

[0078] Synthesis Example 4

[0079] The preparation method was the same as in Example 1, except that compounds A-4 (3.83 g; 10 mmol) and B-4 (3.12 g; 10 mmol) were used to replace compounds A-1 and B-1, and the final product C-4 was obtained: 3.71 g, yield: 65%, MS (m / z) (M+): 570.

[0080] Synthesis Example 5

[0081] The preparation method was the same as in Example 1, except that compounds A-5 (4.33 g; 10 mmol) and B-5 (3.12 g; 10 mmol) were used to replace compounds A-1 and B-1, and the final product C-5 was obtained: 4.34 g, yield: 70%, MS (m / z) (M+): 620.

[0082] Synthesis Example 6

[0083] The preparation method was the same as in Example 1, except that compounds A-6 (3.88 g; 10 mmol) and B-6 (3.12 g; 10 mmol) were used to replace compounds A-1 and B-1, and the final product C-6 was obtained: 3.74 g, yield: 65%, MS (m / z) (M+): 575.

[0084] Synthesis Example 7

[0085] The preparation method was the same as in Example 1, except that compounds A-7 (3.83 g; 10 mmol) and B-7 (3.12 g; 10 mmol) were used to replace compounds A-1 and B-1, and the final product C-7 was obtained: 4.28 g, yield: 75%, MS (m / z) (M+): 570.

[0086] Synthesis Example 8

[0087] The preparation method was the same as in Example 1, except that compounds A-8 (4.33 g; 10 mmol) and B-8 (3.12 g; 10 mmol) were used to replace compounds A-1 and B-1, and the final product C-8 was obtained: 4.35 g, yield: 70%, MS (m / z) (M+): 620.

[0088] Synthesis Example 9

[0089] The preparation method was the same as in Example 1, except that compounds A-9 (4.33 g; 10 mmol) and B-9 (3.12 g; 10 mmol) were used to replace compounds A-1 and B-1, and the final product C-9 was obtained: 4.84 g, yield: 78%, MS (m / z) (M+): 620.

[0090] Synthesis Example 10

[0091] The preparation method was the same as in Example 1, except that compounds A-10 (3.93 g; 10 mmol) and B-10 (3.12 g; 10 mmol) were replaced with compounds A-1 and B-1, and the final product C-10 was obtained: 4.01 g, yield: 69%, MS (m / z) (M+): 580.

[0092] Synthesis Example 11

[0093] The preparation method was the same as in Synthesis Example 1, except that compounds A-11 (4.33 g; 10 mmol) and B-11 (3.12 g; 10 mmol) were replaced with compounds A-1 and B-1, and the final product C-11 was obtained: 4.6 g, yield: 74%, MS (m / z) (M+): 620.

[0094] Synthesis Example 12

[0095] The preparation method was the same as in Example 1, except that compounds A-12 (4.33 g; 10 mmol) and B-12 (3.12 g; 10 mmol) were replaced with compounds A-1 and B-1, and the final product C-12 was obtained: 4.97 g, yield: 80%, MS (m / z) (M+): 620.

[0096] Synthesis Example 13

[0097] The preparation method was the same as in Example 1, except that compounds A-13 (4.33 g; 10 mmol) and B-13 (3.23 g; 10 mmol) were replaced with compounds A-1 and B-1, and the final product C-13 was obtained: 4.8 g, yield: 76%, MS (m / z) (M+): 631.

[0098] Synthesis Example 14

[0099] The preparation method was the same as in Synthesis Example 1, except that compounds A-14 (4.33 g; 10 mmol) and B-14 (3.12 g; 10 mmol) were used to replace compounds A-1 and B-1, and the final product C-14 was obtained: 4.35 g, yield: 70%, MS (m / z) (M+): 620.

[0100] Synthesis Example 15

[0101] The preparation method was the same as in Example 1, except that compounds A-15 (4.33 g; 10 mmol) and B-15 (3.12 g; 10 mmol) were replaced with compounds A-1 and B-1, and the final product C-15 was obtained: 4.53 g, yield: 73%, MS (m / z) (M+): 620.

[0102] Synthesis Example 16

[0103] The preparation method was the same as in Example 1, except that compounds A-16 (3.83 g; 10 mmol) and B-16 (3.12 g; 10 mmol) were used to replace compounds A-1 and B-1, and the final product C-16 was obtained: 4.33 g, yield: 76%, MS (m / z) (M+): 570.

[0104] Synthesis Example 17

[0105] The preparation method was the same as in Example 1, except that compounds A-17 (3.88 g; 10 mmol) and B-17 (3.12 g; 10 mmol) were used to replace compounds A-1 and B-1, and the final product C-17 was obtained: 4.14 g, yield: 72%, MS (m / z) (M+): 575.

[0106] Synthesis Example 18

[0107] The preparation method was the same as in Example 1, except that compounds A-18 (3.83 g; 10 mmol) and B-18 (3.12 g; 10 mmol) were used to replace compounds A-1 and B-1, and the final product C-18 was obtained: 4.57 g, yield: 80%, MS (m / z) (M+): 570.

[0108] Synthesis Example 19

[0109] The preparation method was the same as in Example 1, except that compounds A-19 (3.83 g; 10 mmol) and B-19 (3.12 g; 10 mmol) were used to replace compounds A-1 and B-1, and the final product C-19 was obtained: 3.94 g, yield: 69%, MS (m / z) (M+): 570.

[0110] Synthesis Example 20

[0111] The preparation method was the same as in Example 1, except that compounds A-20 (3.83 g; 10 mmol) and B-20 (3.12 g; 10 mmol) were used to replace compounds A-1 and B-1, and the final product C-20 was obtained: 4.45 g, yield: 78%, MS (m / z) (M+): 570.

[0112] Comparative compounds .

[0113] Compound performance evaluation 1. Molecular orientation test Molecular orientation of the materials was tested using VASE: Quartz glass or silicon substrates were sequentially ultrasonically cleaned with deionized water, acetone, and isopropanol for 15 minutes, dried with nitrogen, and then treated with ultraviolet ozone for 15 minutes. Thin films were prepared using vacuum evaporation, with the compounds of this invention and comparative compounds deposited on the substrates at a rate of 1 A / s. The spectral range of 300–800 nm, a step size of 5 nm, and incident angles of 50°, 60°, and 70° were selected for testing the thin films, and the degree of order (S, dimensionless) of the thin films was calculated. The value of S ranged from -0.5 to 1, where -0.5 indicated completely horizontal alignment, 0 indicated isotropic alignment, and 1 indicated completely vertical alignment.

[0114] 2. Evaluation of electron mobility A single-electron device (ITO / Yb (1 nm) / ET01:LiQ=1:1 (30 nm) / analyte compound (i.e., compounds C-1 to C-20 and DB01-DB04) (20 nm) / ET01:LiQ=1:1 (30 nm) / Yb (1 nm) / Al (80 nm)) was fabricated. Based on the current density-voltage curve, the electron mobility μ was calculated using the space charge-confined current SCLC method. e (10 -5 *cm 2 V -1 s -1 For dual-emitting-layer devices, the first emitting layer is responsible for carrier recombination, resulting in the highest carrier density. In particular, the accumulation of holes due to insufficient electrons severely quenches excitons, reducing efficiency. By increasing the electron mobility of the first emitting layer, the electron density can not only consume accumulated holes but also increase the recombination probability, thereby improving device efficiency. The structures of compounds ETO1 and LiQ are shown in Device Example 1.

[0115] The results are shown in Table 1.

[0116] Table 1

[0117] As can be seen from the table above, compared with the comparative compounds, the compounds provided by this invention have better molecular orientation and higher electron mobility. Specifically, using benzanthracene as the first host material core structure and benzofuran-phenanthrene group as the terminal substituent of this invention has significant advantages. Compared with the comparative compounds DB01-DB04, this invention has significant advantages in molecular orientation and electron mobility.

[0118] The only difference between the comparative compound DB01 and the compound C-21 of the present invention is the use of a different parent nucleus. The parent nucleus of the present invention is benzene, which has a T1 energy level of about 2.06 eV, while the T1 energy level of the anthracene nucleus is 1.73 eV. When the comparative compound DB01 is used as the first host material, its T1 energy level is comparable to that of the second host material (e.g., BH2-01 used in the present invention). Therefore, the transfer of triplet excitons from the first luminescent layer to the second luminescent layer will not occur, and the dual luminescent layer mechanism cannot be fully utilized. Compared with the comparative compound DB02, the benzofuran-phenanthrene group of this invention has a larger molecular weight and π-electron conjugation surface. On the one hand, it can maximize the permanent spontaneous orientation polarization effect. On the other hand, due to the steric hindrance formed by the phenyl angular fused ring structure of the benzanthracene core, the benzofuran-phenanthrene group of this invention has a larger spatial structure than the benzofuran-naphthyl group of the comparative compound, resulting in a compound with better rigidity, which is conducive to obtaining better molecular orientation. In particular, the molecular orientation data of compound C-15 of this invention is significantly improved compared with the comparative compound DB02. Compared with comparative compounds DB03 and DB04, the substitution site of this invention is located on the phenanthrene segment of the benzofuran-phenanthrene group, while the substitution site of the comparative compounds is located on the phenyl group on the other side. The dielectric constants (F / m) of benzene, naphthalene, and phenanthrene are approximately 2.28, 2.5, and 3.08, respectively. A larger dielectric constant is more conducive to obtaining a larger surface charge. The substitution site of this invention is located on the phenanthrene group, which is conducive to obtaining a larger dielectric constant to improve the carrier injection process. In addition, carrier transport mainly occurs on the parent nucleus with coplanar π electrons and the fused ring directly connected to it. A larger fused ring connected to the benzofuran-anthracene nucleus is more conducive to improving the electron transport performance of the material. It can be seen that the electron transport characteristics of the material of this invention are significantly improved compared with the comparative example, thus significantly reducing the quenching effect of holes on excitons. The addition of two phenyl groups to the comparative compound DB03 significantly increases the molecular degrees of freedom. The free rotation of the phenyl groups and the free rotation of the benzofuran-phenanthrene group after moving away from the benzofuran-anthracene group significantly enhance the vibrational relaxation of the molecules, increasing the vibrational relaxation loss in energy transfer.

[0119] OLED manufacturing and characterization Device Examples The organic electroluminescent device provided by the present invention includes an anode, a hole transport region, a first light-emitting layer, a second light-emitting layer, an electron transport region, and a cathode sequentially disposed on a substrate. Furthermore, the hole transport region includes a hole injection layer, a hole transport layer, and a light-emitting auxiliary layer; the electron transport region includes an electron transport layer and an electron injection layer.

[0120] Furthermore, the first light-emitting layer is composed of a first host material and a dopant material, and the host material of the first light-emitting layer can be composed of one molecular material or multiple molecular materials.

[0121] Furthermore, the second light-emitting layer is composed of a second host material and a dopant material, and the host material of the second light-emitting layer can be composed of one molecular material or multiple molecular materials.

[0122] The compound described in this invention can be used in the first light-emitting layer of the aforementioned organic electroluminescent device.

[0123] In this embodiment, the anode uses a commonly used anode material in the art, such as ITO, Ag, or their multilayer structures. The hole injection layer uses a commonly used hole injection material in the art, with F4TCNQ, HATCN, NDP-9, etc., added for doping. The hole transport layer uses a commonly used hole transport material in the art. The light-emitting layer uses the host and guest material composition provided by this invention. The electron transport layer uses a commonly used electron transport material in the art. The electron injection layer uses a commonly used electron injection material in the art, such as LiQ, LiF, Yb, etc. The cathode uses a commonly used material in the art, such as metallic Al, Ag, or metal mixtures (Ag-doped Mg, Ag-doped Ca, etc.).

[0124] The electrode fabrication method and the deposition method of each functional layer in this embodiment are conventional methods in the art, such as vacuum thermal evaporation or inkjet printing, and will not be described in detail here. Only some process details and testing methods in the fabrication process are supplemented as follows: Device Example 1 The substrates used in this invention are all subjected to the following operations: the ITO / Ag / ITO substrate is patterned to give it a light-emitting area of ​​3mm × 3mm, then ultrasonicated with water / isopropanol, irradiated with UV / ozone, and then dried at 100°C. Afterwards, the ITO / Ag / ITO substrate is mounted on the substrate support of a vacuum deposition apparatus, and the pressure is adjusted to make the vacuum rate 1 × 10⁻⁶. -7The following operations were then performed: First, a hole injection layer was formed on the ITO layer (anode) formed on the substrate by vacuum deposition of compounds HT01 and PD01 (mass ratio of HT01 to PD01 of 97:3) with a thickness of 10 nm. Next, a hole transport layer was formed on the hole injection layer by vacuum deposition of compound HT01 with a thickness of 100 nm. Then, an electron blocking layer was formed on the hole transport layer by vacuum deposition of compound BP01 with a thickness of 5 nm. A first host material C-1 and a dopant material BD01 were co-deposited on the electron blocking layer, such that the mass ratio of compound C-1 to compound BD01 was 97:3, forming a first light-emitting layer with a thickness of 5 nm. A second host material BH2-01 and a dopant material BD01 were co-deposited on the first light-emitting layer, such that the mass ratio of compound BH2-01 to compound BD01 was 98:2, forming a second light-emitting layer with a thickness of 15 nm. Compound HB01 was vapor-deposited on the second emitting layer to form a hole-blocking layer with a thickness of 5 nm. Then, on the hole-blocking layer, compound ET01 and compound LiQ (mass ratio of ET01 to LiQ 1:1) were vacuum-deposited to a thickness of 30 nm to form an electron transport layer. Next, Yb was vacuum-deposited to a thickness of 1 nm on the electron transport layer to form an electron injection layer. Then, Mg and Ag (mass ratio of Mg to Ag 1:9) were deposited to a thickness of 15 nm on the electron injection layer to form a cathode. Finally, compound CP01 was deposited to a thickness of 50 nm on the cathode to form a capping layer. The vapor-deposited substrate was then encapsulated. A UV adhesive was applied to the cleaned cover plate using a coating equipment. The coated cover plate was then moved to the lamination section, and the vapor-deposited substrate was placed on top of the cover plate. Finally, the substrate and cover plate were laminated using a bonding equipment, and the UV adhesive was simultaneously photocured to fabricate a top-emitting organic light-emitting device. The device structure is described in [reference needed]. Figure 1 .

[0125] Except for the first host material C-1, the molecular structural formulas of the remaining layers are as follows:

[0126]

[0127] .

[0128] Device Examples 2-20 Using the above method, organic electroluminescent devices were prepared from the compounds described in other embodiments in Table 2. Specifically, blue organic electroluminescent devices Examples 2-20 were prepared by replacing compound C-1 in device Example 1 with the first host material shown in Table 2.

[0129] Device Comparison Examples 1-4 Organic electroluminescent devices were prepared by using the above method to replace compound C-1 in device example 1 with the first host material shown in Table 2. Specifically, blue organic electroluminescent devices (Comparative Examples 1-4) were prepared by replacing compound C-1 in device example 1 with the first host material shown in Table 2.

[0130] The OLED devices described above were tested using standard methods. For this purpose, J = 10 mA / cm² was used. 2 The driving voltage and luminous efficiency of the organic electroluminescent device were determined at a current density of J = 20 mA / cm². LT97 indicates that the fabricated blue light-emitting device is capable of operating at this current density. 2 When operating, the luminous intensity drops to 97% of its initial value L0 after time LT97.

[0131] The testing instruments and methods used to perform performance testing on the OLED devices of the above embodiments and comparative examples are as follows: Luminous efficacy (CE) (cd / A) and chromaticity coordinates (CIEy) were measured using a PhotoResearch PR-655 spectral scanner. Current density and turn-on voltage: tested using a Keithley 2400 digital source meter; The luminous efficiency of blue light devices is greatly affected by chromaticity. The industry generally uses the BI value as the basis for the efficiency of blue light devices. BI (Blue index) is obtained by dividing the luminous efficiency CE (cd / A) by the chromaticity coordinate (CIEy). The performance test results of the above devices are listed in Table 2.

[0132] Table 2

[0133] As can be seen from the above device evaluation results, compared with the device comparison, the device embodiment has a lower driving voltage and higher efficiency.

[0134] Compared with the device embodiments of the present invention, the compound DB01 used in Comparative Example 1, due to its use of anthracene as the parent nucleus, has an insufficiently high T1 energy level, resulting in the inability to utilize the dual-emissivity mechanism and a significant reduction in device efficiency. The compound DB02 used in Comparative Example 2 does not employ the benzofuran-phenanthrene substituent introduced in this invention, and its molecular orientation and electron transport are inferior to those of the compounds in this invention, thus performing poorly in reducing voltage and improving efficiency. Furthermore, the sites of direct connection between compounds DB03 and DB04 used in Comparative Examples 3-4 and the benzofuran-phenanthrene parent nucleus are not located at the benzofuran-phenanthrene substituent. The electron mobility of the phenanthrene fragment is poor compared to that of the present invention. In addition, the comparative compound DB03 has an additional part of free molecular rotation, which increases the loss of energy transfer between molecules. The excessively long connecting group also increases the distance between the intermolecular benzene and anthracene, which is not only detrimental to voltage drop, but also results in poor efficiency. The comparative compound DB04 has a substitution on the phenyl group of the benzofuran phenanthrene group, which makes the furan ring closer to the benzene and anthracene core rather than the molecular periphery. This is not effective in improving intermolecular interactions through the high electronegativity of oxygen, and thus is not conducive to further improvement of molecular orientation, resulting in poor device performance. Furthermore, as shown in Device Examples 1-15, when a group on one side of the first host material molecule has a steric hindrance that prevents the substituent from rotating freely, the rigidity of the molecule is strengthened, which helps to reduce the energy loss caused by vibrational relaxation during carrier transport. This results in better efficiency performance compared to Device Examples 16-20. Moreover, as shown in Device Examples 1-10, when a sterically hindered aryl substituent is avoided at position 7 of the first host material molecule, such as the 2-naphthyl substituent shown on the left side of the figure below, the coupling impurities on the right side can be effectively prevented from forming during thermal processes such as sublimation and vapor deposition, thereby making Examples 1-10 perform better in terms of voltage.

[0135]

[0136] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. An organic compound for use in blue light devices, characterized in that, The general structural formula of the organic compound is shown below: I； R1 is selected from one of the following structures: 、 、 、 、 、 、 、 、 、 、 ； 、 、 、 、 、 、 、 ； R2 is selected from any one of phenyl, naphthyl, phenanthryl, and biphenyl; In Formula I, any one of the hydrogen atoms can be replaced by deuterium.

2. The organic compound according to claim 1, characterized in that, R2 is selected from one of the following structures: 、 、 、 、 、 。 3. The organic compound according to claim 1, characterized in that, R2 is selected from one of the following structures: 、 、 、 。 4. An organic compound for use in blue light devices, characterized in that, The organic compound is selected from one of the following structures: I-1、 I-2; Wherein, the R 11 Selected from Any one of them.

5. An organic compound for use in blue light devices, characterized in that, The organic compound is selected from one of the following structures: 。 6. A blue organic electroluminescent device, characterized in that, It includes an anode, a hole transport region, a light-emitting layer, an electron transport region, and a cathode sequentially disposed on a substrate; wherein the light-emitting layer comprises an organic compound as described in any one of claims 1 to 5.

7. A double-emitting-layer blue organic electroluminescent device, characterized in that, It includes an anode, a hole transport region, a first light-emitting layer, a second light-emitting layer, an electron transport region, and a cathode, which are sequentially disposed on a substrate; wherein the first light-emitting layer includes the organic compound according to any one of claims 1 to 5.

8. The dual-emitting-layer blue organic electroluminescent device according to claim 7, characterized in that, The first light-emitting layer comprises a first host material and a dopant material, wherein the first host material is selected from the organic compounds described in any one of claims 1 to 5.

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