Organic electroluminescent compound and organic electroluminescent device containing same

Abstract

The invention discloses an organic electroluminescent compound and an organic electroluminescent device comprising the same. The organic electroluminescent compound is selected from a general formula structure as shown in a formula I in the specification. In the invention, by introducing a special molecular structure formed by aryl substituent groups on two specific sites, namely Ar2 and Ar3 positions, the following effects are generated: firstly, a carbon-hydrogen bond of a fused aryl fragment on relatively weak fused aryl benzofuran is substituted by aryl and then becomes a more stable carbon-carbon bond; secondly, a special spatial three-dimensional structure can improve the transmission of carriers, reduce the retention of polaron in the device on a single molecule, and reduce the probability of interaction of polaron, exciton, carriers and the like, thereby reducing the quenching and degradation of a main body material in the operation process of the device, prolonging the service life of the device, and improving the efficiency of the device; and thirdly, the recombination energy of current carriers is obviously reduced, so that the current carriers are transmitted more quickly, and the voltage of the device is reduced. # imgabs0 # I

Description

Technical Field

[0001] The present invention belongs to the technical field of OLED, and specifically includes an organic electroluminescent compound and an organic electroluminescent device containing the same. Background Art

[0002] As a new generation of flat panel display technology, organic electroluminescent devices (OLEDs) have experienced rapid development over the past two decades. With their ultra-thin structure, fast response, and excellent display performance, they have gradually become the core technology in the display field. Through high-contrast display effects and wide color gamut coverage capabilities, this technology can accurately present high-saturation red, green, and blue primary colors, thus creating a visually stunning experience with vivid and realistic colors. Based on these significant advantages, OLEDs have not only been successfully applied in mainstream fields such as flat panel displays and flexible displays, but also demonstrated unique technical value in in-vehicle display systems and solid-state lighting solutions, continuously driving the innovation process in the display industry.

[0003] In the research on optimizing the performance of blue light devices, the development of host materials for the light-emitting layer faces multiple technical bottlenecks. Currently, mainstream phosphorescent materials and traditional thermally activated delayed fluorescence (TADF) materials have not achieved commercial breakthroughs due to significant efficiency roll-off; while fluorescent materials and multi-resonance TADF (MR-TADF) materials are still limited by the 25% singlet exciton theoretical limit in electroluminescence. In response to this core challenge, the academic community has proposed an innovative solution for the host-guest doping system, that is, by introducing anthracene-based host materials with a triplet-triplet exciton fusion (TTU) mechanism, theoretically, the internal quantum efficiency of the device can break through the traditional limit and reach a theoretical peak of 40%. This mechanism can significantly improve the exciton utilization rate by promoting the effective fusion of triplet excitons. However, in practical applications, only a few material systems can approach the 40% theoretical limit. This is mainly due to the non-linear quenching effects caused by the increase in exciton density: the aggravation of singlet exciton-polaron quenching (SPA) and triplet exciton-triplet exciton annihilation (TTA), which poses strict spatial constraints on the distribution of the light-emitting layer recombination region. To effectively suppress such non-radiative losses, the host material needs to have both excellent charge transport capabilities and carrier balance capabilities. However, the current anthracene-based material systems generally have the problem that the hole mobility is significantly higher than the electron mobility. This imbalance in carrier transport leads to the broadening of the recombination region and becomes a key factor restricting the further improvement of device efficiency.

[0004] In recent years, by introducing dibenzofuran and naphthylbenzofuran fragments into anthracene-based main materials, the larger electronegativity of oxygen is utilized to improve the electronic transmission performance of the material. However, the carbon-oxygen bond may break in the anionic state, causing the material to deteriorate and shortening the service life of the material. To improve this problem, the use of full deuteration or partial deuteration can improve the stability of the material. However, the use of deuteration, especially full deuteration, may cause the transmission to slow down. In addition, the cost of deuteration is high, and the deuteration rate is not easy to monitor and control. Therefore, how to modify the current mainstream anthracene-based main materials containing furan fragments without deliberately using deuteration modification, so that it can show better charge transfer, carrier balance performance and excellent stability while having higher efficiency, is still an important issue that needs to be solved and improved in this industry. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention provides an organic electroluminescent compound and an organic electroluminescent device comprising the same.

[0006] To achieve the above objectives, the technical solutions adopted by the present invention include: The first aspect of the present invention provides an organic electroluminescent compound, wherein the organic electroluminescent compound is selected from the general structure shown in the following formula I: I; in, Ar 1 A combination of any one or more selected from substituted or unsubstituted aryl groups having 6 to 60 carbon atoms, substituted or unsubstituted condensed ring aryl groups having 10 to 60 carbon atoms, and substituted or unsubstituted condensed ring heteroaryl groups having 8 to 60 carbon atoms, when Ar 1 When a substituent is present, the substituent is selected from deuterium or phenyl; Ar 4 A structure selected from formula II-1 to formula II-4: II-1, II-2, II-3, II-4; Ar 2 ,Ar 3 Each is independently selected from any one of deuterated or non-deuterated phenyl, deuterated or non-deuterated naphthyl; D represents deuterium, and represents a bonding site with anthracene in formula I; n 1 Select from 0 or 8, n 2 、n 4 、n 5 Each independently selected from 0 or 6, n 3Selected from 0 or 3, n 6 Selected from 0 or 4.

[0007] Furthermore, Ar 1 Selected from a composition of any one or more of a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted condensed polycyclic aryl group having 10 to 30 carbon atoms, and a substituted or unsubstituted condensed polycyclic heteroaryl group having 8 to 30 carbon atoms.

[0008] Furthermore, the aryl group is selected from any one of phenyl, biphenyl, dimethylfluorenyl, diphenylfluorenyl, and spirofluorenyl.

[0009] Furthermore, the condensed polycyclic aryl group is selected from any one of naphthyl, phenanthryl, pyrenyl, benzanthryl, benzophenanthryl, chrysenyl, and fluoranthenyl.

[0010] Furthermore, the heteroatom in the condensed polycyclic heteroaryl group is selected from any one of oxygen, nitrogen, and silicon.

[0011] Furthermore, the condensed polycyclic heteroaryl group is selected from one of the structures shown below: .

[0012] Furthermore, the Ar 2 , Ar 3 is selected from phenyl.

[0013] Furthermore, the Ar 1 is selected from phenyl.

[0014] Furthermore, the organic electroluminescent compound is selected from one of the structures shown below:

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039] 。

[0040] The second aspect of the present invention provides an organic electroluminescent device, which includes an anode, a hole transport region, a light-emitting layer, an electron transport region, and a cathode that are sequentially disposed on a substrate; wherein, the light-emitting layer includes one or more of the above-described organic electroluminescent compounds.

[0041] Further, the light-emitting layer includes a host material and a guest material, wherein, the host material includes one or more of the above-described organic electroluminescent compounds.

[0042] Further, the light-emitting layer includes a first host material, a second host material, and a guest material, that is, the device is a dual-host device. The first host material is selected from the compounds shown in Formula III below, and the second host material includes one or more of the above-mentioned organic electroluminescent compounds: III; Ar 5 is selected from any one of aryl groups having 6 to 30 carbon atoms, aryl groups having 6 to 30 carbon atoms substituted with benzene, polycyclic aryl groups having 10 to 30 carbon atoms, and polycyclic aryl groups having 10 to 30 carbon atoms substituted with benzene; Ar 6 is selected from aryl groups having 6 to 30 carbon atoms, aryl groups having 6 to 30 carbon atoms substituted with benzene, polycyclic aryl groups having 10 to 30 carbon atoms, polycyclic aryl groups having 10 to 30 carbon atoms substituted with benzene, or 2-dibenzofuran.

[0043] Further, in the dual-host device, the first host material is selected from one of the following structures: .

[0044] Further, the light-emitting layer includes a first light-emitting layer located above the hole transport region and a second light-emitting layer located above the first light-emitting layer, that is, the device is a dual-light-emitting layer device. Among them, the first light-emitting layer includes a first host material and a guest material. The first host material is selected from the compounds shown in Formula IV below, the second light-emitting layer includes a second host material and a guest material, and the second host material includes one or more of the above-mentioned organic electroluminescent compounds: IV; Ar 7 is selected from any one of H, aryl groups having 6 to 30 carbon atoms, and polycyclic aryl groups having 10 to 30 carbon atoms; Ar 8 is selected from any one of H, aryl groups having 6 to 30 carbon atoms, and polycyclic aryl groups having 10 to 30 carbon atoms; L is selected from phenyl or biphenyl.

[0045] Further, in the dual-light-emitting layer device, the first host material is selected from one of the following structures: .

[0046] Advantages of the present invention: The present invention provides an organic electroluminescent compound. By introducing substituents at two specific positions (i.e., Ar 2 and Ar 3At the (position), a special molecular structure formed by introducing aryl substituents has the following effects: First, after the carbon-hydrogen bond on the phenyl group connected in parallel with the furan on the aryl fragment of the relatively weak condensed aryl benzofuran is substituted by an aryl group, it becomes a more stable carbon-carbon bond, improving the thermal stability of the material; Second, the special three-dimensional spatial structure can improve the carrier transport, reduce the time for polarons to stay on a single molecule in the device, and reduce the probability of interactions between polarons, excitons, carriers, etc., thereby reducing the quenching and deterioration of the host material during the operation of the device, and thus improving the lifespan of the device; Third, it significantly reduces the carrier recombination energy, enables the carriers to be transported faster, which is conducive to reducing the device voltage and improving the device efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 FIG. is a schematic structural diagram of the organic electroluminescent device of the present invention, wherein, 101 - Substrate 1, 102 - Anode 1, 103 - Hole injection layer 1, 104 - Hole transport layer 1, 105 - Luminescence assisting layer 1, 106 - Luminescent layer, 107 - Hole blocking layer 1, 108 - Electron transport layer 1, 109 - Electron injection layer 1, 1010 - Cathode 1.

[0048] Figure 2 FIG. is a molecular conformation diagram of Compound C3.

[0049] Figure 3 FIG. is a molecular conformation diagram of Compound DB01.

[0050] Figure 4 FIG. is a molecular conformation diagram of Compound DB10.

[0051] Figure 5 FIG. is a schematic structural diagram of the double-luminescent layer organic electroluminescent device of the present invention, wherein, 201 - Substrate 2, 202 - Anode 2, 203 - Hole injection layer 2, 204 - Hole transport layer 2, 205 - Luminescence assisting layer 2, 206 - First luminescent layer, 207 - Second luminescent layer, 208 - Hole blocking layer 2, 209 - Electron transport layer 2, 2010 - Electron injection layer 2, 2011 - Cathode 2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0052] In order to understand the content of the present invention more clearly, it will be described in detail in conjunction with the drawings and embodiments.

[0053] The compounds of the present invention are applicable to light-emitting elements, display panels, and electronic devices, and are particularly applicable to organic electroluminescent devices. The electronic devices described in the present invention are devices including at least one layer of an organic compound, and the devices may also include inorganic materials or layers formed entirely of inorganic materials. The electronic devices are preferably 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 photoreceptors, organic field quenching devices (O-FQDs), light-emitting electrochemical cells (LECs), organic laser diodes (O-lasers), and organic plasma emission devices. The electronic devices are preferably organic electroluminescent devices (OLEDs). Schematic structural diagrams of exemplary organic electroluminescent devices are as shown in Figure 1 or Figure 5 shown.

[0054] Experimental Section To more clearly understand the content of the present invention, the polycyclic compounds, the preparation methods of the compounds, and the light-emitting characteristics of the devices will be explained in detail in combination with examples. Various chemical reactions can be applied to the synthesis methods of the compounds of one embodiment of the present invention. However, it should be noted that the synthesis methods of the compounds of one embodiment of the present invention are not limited to the synthesis methods described below. Unless otherwise specified, subsequent syntheses are carried out in an anhydrous solvent under a protective gas atmosphere. Solvents and reagents can be purchased from conventional reagent suppliers.

[0055] General formula and examples of intermediate synthesis

[0056] In a 250 mL three-necked flask, 50 mL of toluene, 25 mL of ethanol, and 25 mL of water were added under nitrogen protection, and then Dn (10 mmol), En (10 mmol), potassium carbonate (4.15 g, 30 mmol), and tetrakis(triphenylphosphine)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, it was cooled to room temperature, filtered, and the filter cake was dissolved in hot toluene and filtered to remove solid insoluble substances, and then recrystallized to obtain the product Fn. In a 250 mL three-necked flask, 100 mL of toluene was added under nitrogen protection, and then Fn (20 mmol), Gn (10 mmol), cesium carbonate (9.78 g, 30 mmol), and [Cp*RhCl 2 2 (0.31 g, 0.5 mmol), Cu(OAc) 2 •H 2 ​O (4.00 g, 20 mmol) was heated to 125 °C and reacted for 12 h. After the reaction was completed, it was cooled to room temperature, filtered, and the filter cake was dissolved in hot toluene and filtered to remove solid insoluble substances, and then recrystallized to obtain product Hn.

[0057] Intermediate Hn (10 mmol), trimethyl borate (1.03 g, 10 mmol), and tetrahydrofuran (30 mL) were added to a round-bottom flask purged with nitrogen. tert-Butyllithium (8.00 mL, 20 mmol) was added dropwise at -50 °C under nitrogen protection, and the addition was completed within 2 h. The mixture was kept warm for 3 h, then 3.5 mL of 5% hydrochloric acid solution was added, and stirring was continued for 2 h. Tetrahydrofuran was distilled off under reduced pressure. When the temperature dropped to 10 °C, solid precipitation occurred. It was filtered by suction and dried to obtain intermediate Jn.

[0058] In a 250 mL three-necked flask, 50 mL of toluene, 25 mL of ethanol, and 25 mL of water were added under nitrogen protection, and then Jn (10 mmol), Kn (10 mmol), potassium carbonate (4.15 g, 30 mmol), and tetrakis(triphenylphosphine)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, it was cooled to room temperature, filtered, and the filter cake was dissolved in hot toluene and filtered to remove solid insoluble substances, and then recrystallized to obtain product An.

[0059] The preparation process of intermediate A1 is shown below as an example, and the preparations of intermediates A2 - A20 can be carried out with reference to this process.

[0060]

[0061] In a 250 mL three-necked flask, 50 mL of toluene, 25 mL of ethanol, and 25 mL of water were added under nitrogen protection, and then D1 (2.31 g, 10 mmol), E1 (1.27 g, 10 mmol), potassium carbonate (4.15 g, 30 mmol), and tetrakis(triphenylphosphine)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, it was cooled to room temperature, filtered, and the filter cake was dissolved in hot toluene and filtered to remove solid insoluble substances, and then recrystallized to obtain product F1: 2.37 g, yield: 85%, MS (m / z) (M+): 279. In a 250 mL three-necked flask, 100 mL of toluene was added under nitrogen protection, and then F1 (5.58 g, 20 mmol), G1 (1.78 g, 10 mmol), cesium carbonate (9.78 g, 30 mmol), and [Cp*RhCl 2 2 (0.31 g, 0.5 mmol), Cu(OAc) 2 •H 2 ​O (4.00 g, 20 mmol) was heated to 125 °C and reacted for 24 h. After the reaction, it was cooled to room temperature, filtered, and the filter cake was dissolved in hot toluene and filtered to remove solid insoluble substances. Then, recrystallization was carried out to obtain product H1: 2.50 g, yield: 55%, MS (m / z) (M+): 455.

[0062] To a round-bottom flask purged with nitrogen were added intermediate H1 (4.55 g, 10 mmol), trimethyl borate (1.03 g, 10 mmol), and tetrahydrofuran (30 mL). Under nitrogen protection, tert-butyllithium (8.00 mL, 20 mmol) was added dropwise at -50 °C, and the addition was completed within 2 h. After keeping warm for 3 h, 3.5 mL of 5% hydrochloric acid solution was added, and stirring was continued for 2 h. Tetrahydrofuran was distilled off under reduced pressure. When the temperature was lowered to 10 °C, solid precipitation occurred. It was filtered by suction and dried to obtain intermediate J1: 3.78 g, yield: 90%, MS (m / z) (M+): 420.

[0063] In a 250 mL three-necked flask, 50 mL of toluene, 25 mL of ethanol, and 25 mL of water were added under nitrogen protection. Then, J1 (4.20 g, 10 mmol), K1 (3.36 g, 10 mmol), potassium carbonate (4.15 g, 30 mmol), and tetrakis(triphenylphosphine)palladium (0.35 g, 0.3 mmol) were added. The mixture was heated to 80 °C and reacted for 12 h. After the reaction, it was cooled to room temperature, filtered, and the filter cake was dissolved in hot toluene and filtered to remove solid insoluble substances. Then, recrystallization was carried out to obtain product A1: 5.81 g, yield: 86%, MS (m / z) (M+): 675.

[0064] Synthesis Example 1

[0065] In a 250 mL three-necked flask, 50 mL of toluene, 25 mL of ethanol, and 25 mL of water were added under nitrogen protection. Then, A1 (6.76 g; 10 mmol), B1 (1.53 g; 10 mmol), potassium carbonate (4.15 g, 30 mmol), and tetrakis(triphenylphosphine)palladium (0.35 g, 0.3 mmol) were added. The mixture was heated to 80 °C and reacted for 12 h. After the reaction, it was cooled to room temperature, filtered, and the filter cake was dissolved in hot toluene and filtered to remove solid insoluble substances. Then, recrystallization was carried out to obtain product C1: 6.67 g, yield: 89%, MS (m / z) (M+): 749.

[0066] Synthesis Example 2

[0067] The preparation method is the same as that of Synthesis Example 1, except that A2 (6.76 g; 10 mmol) and B2 (1.53 g; 10 mmol) are used to replace A1 and B1, and finally product C2 is obtained: 6.44 g (yield: 86%), MS (m / z) (M+): 749.

[0068] Synthesis Example 3

[0069] The preparation method is the same as that of Example 1, except that A3 (6.26 g; 10 mmol) and B3 (0.77 g; 10 mmol) are used to replace A1 and B1, and finally product C3 is obtained: 5.48 g, yield: 88%, MS (m / z) (M+): 623.

[0070] Synthesis Example 4

[0071] The preparation method is the same as that of Synthesis Example 1, except that A4 (6.84 g; 10 mmol) and B4 (0.77 g; 10 mmol) are used to replace A1 and B1, and finally product C4 is obtained: 5.86 g (yield: 86%), MS (m / z) (M+): 681.

[0072] Synthesis Example 5

[0073] The preparation method is the same as that of Example 1, except that A5 (6.84 g; 10 mmol) and B5 (1.27 g; 10 mmol) are used to replace A1 and B1, and finally product C5 is obtained: 6.51 g (yield: 89%), MS (m / z) (M+): 731.

[0074] Synthesis Example 6

[0075] The preparation method is the same as that of Example 1, except that A6 (6.26 g; 10 mmol) and B6 (1.77 g; 10 mmol) are used to replace A1 and B1, and finally product C6 is obtained: 6.15 g, yield: 85%, MS (m / z) (M+): 723.

[0076] Synthesis Example 7

[0077] The preparation method is the same as that of Example 1, except that A7 (6.29 g; 10 mmol) and B7 (2.01 g; 10 mmol) are used to replace A1 and B1, and finally product C7 is obtained: 6.38 g, yield: 85%, MS (m / z) (M+): 750.

[0078] Synthesis Example 8

[0079] The preparation method is the same as that of Example 1, except that A8 (6.34 g; 10 mmol) and B8 (2.29 g; 10 mmol) are used to replace A1 and B1, and finally product C8: 6.89 g is obtained, with a yield of 88%, MS (m / z) (M+): 783.

[0080] Synthesis Example 9

[0081] The preparation method is the same as that of Example 1, except that A9 (6.29 g; 10 mmol) and B9 (2.32 g; 10 mmol) are used to replace A1 and B1, and finally product C9: 6.93 g is obtained, with a yield of 88%, MS (m / z) (M+): 788.

[0082] Synthesis Example 10

[0083] The preparation method is the same as that of Example 1, except that A10 (6.79 g; 10 mmol) and B10 (2.03 g; 10 mmol) are used to replace A1 and B1, and finally product C10: 7.06 g (yield: 88%) is obtained, MS (m / z) (M+): 802.

[0084] Synthesis Example 11

[0085] The preparation method is the same as that of Example 1, except that A11 (6.84 g; 10 mmol) and B11 (1.93 g; 10 mmol) are used to replace A1 and B1, and finally product C11: 7.09 g (yield: 89%) is obtained, MS (m / z) (M+): 797.

[0086] Synthesis Example 12

[0087] The preparation method is the same as that of Example 1, except that A12 (6.76 g; 10 mmol) and B12 (0.82 g; 10 mmol) are used to replace A1 and B1, and finally product C12: 5.9 g (yield: 87%) is obtained, MS (m / z) (M+): 678.

[0088] Synthesis Example 13

[0089] The preparation method was the same as that of Example 1, except that A13 (6.34 g; 10 mmol) and B13 (0.82 g; 10 mmol) were used to replace A1 and B1. Finally, 5.6 g of product C13 was obtained, with a yield of 88%, and MS (m / z) (M+): 636.

[0090] Synthesis Example 14

[0091] The preparation method was the same as that of Example 1, except that A14 (6.26 g; 10 mmol) and B14 (3.15 g; 10 mmol) were used to replace A1 and B1. Finally, 7.4 g of product C14 was obtained, with a yield of 86%, and MS (m / z) (M+): 861.

[0092] Synthesis Example 15

[0093] The preparation method was the same as that of Example 1, except that A15 (6.76 g; 10 mmol) and B15 (2.03 g; 10 mmol) were used to replace A1 and B1. Finally, 7.19 g of product C15 was obtained (yield: 90%), and MS (m / z) (M+): 799.

[0094] Synthesis Example 16

[0095] The preparation method was the same as that of Example 1, except that A16 (7.26 g; 10 mmol) and B16 (0.82 g; 10 mmol) were used to replace A1 and B1. Finally, 6.41 g of product C16 was obtained (yield: 88%), and MS (m / z) (M+): 728.

[0096] Synthesis Example 17

[0097] The preparation method was the same as that of Example 1, except that A17 (6.76 g; 10 mmol) and B17 (0.77 g; 10 mmol) were used to replace A1 and B1. Finally, 6.06 g of product C17 was obtained, with a yield of 90%, and MS (m / z) (M+): 673.

[0098] Synthesis Example 18

[0099] The preparation method was the same as that of Example 1, except that A18 (7.26 g; 10 mmol) and B18 (1.27 g; 10 mmol) were used to replace A1 and B1. Finally, product C18 was obtained: 6.8 g, yield: 88%, MS (m / z) (M+): 773.

[0100] Synthesis Example 19

[0101] The preparation method was the same as that of Example 1, except that A19 (7.26 g; 10 mmol) and B19 (1.27 g; 10 mmol) were used to replace A1 and B1. Finally, product C19 was obtained: 6.65 g, yield: 86%, MS (m / z) (M+): 773.

[0102] Synthesis Example 20

[0103] The preparation method was the same as that of Example 1, except that A20 (6.76 g; 10 mmol) and B20 (3.15 g; 10 mmol) were used to replace A1 and B1. Finally, product C20 was obtained: 7.74 g, yield: 85%, MS (m / z) (M+): 911.

[0104] Compound of Comparative Example

[0105]

[0106]

[0107] 。

[0108] Compound Performance To prove the advantages of the materials of the present invention in terms of carrier recombination energy (including hole recombination energy and electron recombination energy), the carrier recombination energies of different compounds were tested. Generally, the smaller the carrier recombination energy, the faster the carrier transport, and the device test results tend to show the effect of low driving voltage. Through the ORCA software, based on the density functional theory (DFT) calculation method (the basis set level was set to: b3lyp / 6-31g(d), charge number 0), the molecular structure was geometrically optimized (Optimization). On this basis, the recombination energies (eV) of the compound under positive charge and negative charge were further calculated. Generally, the smaller the recombination energy, the faster the mobility, which means that the probability of carriers being trapped by dopants to form traps is lower, the carrier utilization rate is higher, and it is beneficial to improve the efficiency.

[0109] To illustrate the improvement of the material stability by the present invention after substitution, the thermal stability of the material was measured through a thermal stability test. The specific method is as follows: The material to be tested was placed at 280 °C for 240 h for the thermal stability experiment. The high performance liquid chromatography was used to test the change in the purity of the material before and after the thermal stability experiment. The smaller the purity difference, the smaller the degree of degradation reactions such as decomposition and coupling of the material in a long-term high-temperature environment, and the better the thermal stability of the material. When the purity difference before and after the thermal stability is large, it indicates that the material undergoes coupling deterioration in a high-temperature environment, the luminescence performance of the material itself changes, affecting the device life performance. Seriously, the deteriorated material aggravates the quenching of polarons and excitons. Since the compound developed by the present invention is used as the host material and accounts for a major proportion in the light-emitting layer, the purity requirement is stricter than that of the guest material. Usually, its purity is required to be greater than 99.99%. Therefore, when its purity change is less than 0.01%, its thermal stability is evaluated as excellent, and when it is greater than or equal to 0.01%, it is evaluated as poor.

[0110] Table 1

[0111] Analyzing the above results, taking Compound C3 as an example, it can be clearly seen that compared with Comparative Compounds DB02 to DB08 with only one aryl substituent on naphthobenzofuran, Compound C3 has the same anthracene fragment with phenyl substitution, and there are only differences in the number and position of the phenyl groups substituted on naphthobenzofuran. However, the hole / electron recombination energies of the materials of the present invention are 0.19 and 0.29 respectively, which are significantly smaller than those of Comparative Compounds DB02 to DB08. Moreover, the thermal stability of Compound C3 reaches a basically equivalent level compared with Comparative Compound DB01, indicating that the present invention can effectively improve the stability of the material by introducing aryl groups at key sites; especially from Figure 2 the molecular conformation of C3 shown and Figure 3As can be seen from the molecular conformation of DB01 shown, the two substituted phenyl groups greatly restrict the torsion of naphthobenzofuran, increase the molecular rigidity, and reduce the reorganization energy. In addition, the π-electron clouds of the substituted benzene ring and the anthracene nucleus show a certain overlap, which is beneficial to carrier transport and thus beneficial to reducing the voltage in device performance. Compared with the comparative compound DB09, although the electron reorganization energy of the comparative compound DB09 has been improved to a certain extent, in the comparative compound DB09, both ortho-positions of the phenyl group substituted on the anthracene nucleus contain large steric hindrance substituents (see the part circled by the dotted line in the following third structure), which results in a low synthesis yield of the relevant structure. And due to the too large steric hindrance at close range, the single bond connecting the anthracene nucleus and the lower furan part becomes weak, and the change in the molecular structure stability is poor. Compared with the comparative compound DB10, the naphthobenzofuran substituted at the 7th position is adopted in the present invention (see the following first structure). Structurally, the naphthyl structure adopted in the present invention is more electron-rich, and the substitution mode of the present invention enables naphthobenzofuran to form a mutually perpendicular structure based on the anthracene nucleus, with a large steric hindrance. The substituted benzene ring thereon can overlap with the π-electron cloud of the anthracene nucleus to a certain extent, making the change in the reorganization energy small when the present invention structure transfers holes (that is, when the molecule loses an electron). Patent document CN107531661B also shows that the 7th position is similar to the 1st position of dibenzofuran, and it may also reduce the affinity, which is beneficial to electron injection. While the dibenzofuran structure of the comparative compound DB10 lacks a fused ring and thus has a low electron cloud density, and the adopted substitution mode cannot form a mutually perpendicular structure (see Figure 4 ), and the phenyl-substituted dibenzofuran fragment can rotate around the single bond at the 2nd substitution position (see the following second structure). This substitution mode improves the reorganization energy of electron transport, but significantly increases the reorganization energy of hole transport. Usually, the hole transport speed is faster than that of electrons, which may lead to the accumulation of holes at the interface between the hole transport layer and the light-emitting layer, and is not conducive to exciton recombination.

[0112]

[0113] Fabrication and Characterization of OLEDs Device Examples The organic electroluminescent device provided by the present invention includes an anode, a hole transport region, a light-emitting layer, an electron transport region, and a cathode, which are sequentially arranged on a substrate. Further, 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.

[0114] Further, the light-emitting layer is composed of a host material and a guest material, and the host material of the light-emitting layer can be composed of one molecular material or multiple molecular materials.

[0115] The composition described in the present invention can be used in the light-emitting layer of the above-mentioned organic electroluminescent device.

[0116] In the embodiments, the anode uses anode materials commonly used in the art, such as ITO, Ag, or their multi-layer structures. The hole injection layer uses hole injection materials commonly used in the art, and is doped with F4TCNQ, HATCN, NDP-9, etc. The hole transport layer uses hole transport materials commonly used in the art. The light-emitting layer uses the host and guest material compositions provided by the present invention. The electron transport layer uses electron transport materials commonly used in the art. The electron injection layer uses electron injection materials commonly used in the art, such as LiQ, LiF, Yb, etc. The cathode uses materials commonly used in the art, such as metal Al, Ag, or metal mixtures (Mg doped with Ag, Ca doped with Ag, etc.).

[0117] The electrode preparation method and the deposition methods of each functional layer in this embodiment are all conventional methods in the art, such as vacuum thermal evaporation or inkjet printing, etc., which will not be elaborated here. Only some process details and test methods in the preparation process are supplemented and described as follows: Device Example 1 All the substrates used in the present invention are operated as follows: After patterning the ITO substrate so that the light-emitting area has a size of 3 mm × 3 mm, it is ultrasonically treated with water / isopropyl alcohol, irradiated with UV / ozone, then dried at 100 °C. After that, the ITO substrate is installed on the substrate holder of the vacuum deposition device and the pressure is adjusted to make the vacuum rate become 1×10 -7Torr. Subsequently, the following operations are carried out. First, on the ITO layer (anode) formed on the substrate, a hole injection layer is formed by vacuum depositing compound HT01 and compound PD01 with a thickness of 10 nm (the mass ratio of compound HT01 to compound PD01 is 97:3); second, on the above hole injection layer, a hole transport layer is formed by vacuum depositing compound HT01 with a thickness of 100 nm. Second, on the above hole transport layer, a light-emitting auxiliary layer is formed by vacuum depositing compound BP01 with a thickness of 5 nm. Second, on the above light-emitting auxiliary layer, a light-emitting layer is formed by vacuum depositing a mixture of compound C1 provided by the present invention and compound BD01 with a thickness of 20 nm. Among them, compound C1 is used as the host material and compound BD01 is used as the guest material, and the mass ratio of the host material to the guest material is 98:2; then, on the above light-emitting layer, a hole blocking layer is formed by vacuum depositing compound HB01 with a thickness of 5 nm; then, on the above hole blocking layer, an electron transport layer is formed by vacuum depositing compound ET01 and compound LiQ (the mass ratio of compound ET01 to compound LiQ is 1:1) with a thickness of 30 nm; then, on the above electron transport layer, an electron injection layer is formed by vacuum depositing Yb with a thickness of 1 nm. Then, on the above electron injection layer, a cathode is formed by depositing Mg and Ag (the mass ratio of Mg to Ag is 1:9) with a thickness of 15 nm. Then, on the above cathode, a covering layer is formed by depositing compound CP01 with a thickness of 50 nm. Finally, the evaporated substrate is encapsulated. The cleaned cover plate is coated with UV glue using a coating device, and then the coated cover plate is moved to the lamination section. The evaporated substrate is placed on the upper end of the cover plate. Finally, the substrate and the cover plate are laminated under the action of a laminating device, and at the same time, the UV glue is photocured to prepare a top-emitting organic electroluminescent device. The device structure is shown in Figure 1 。

[0118] Except for the host and guest materials of the light-emitting layer, the molecular structural formulas of the materials of the other layers are as follows:

[0119] Device Example 2-20 Using the above method, the compounds described in other examples in Table 2 are made into organic electroluminescent devices, specifically referring to making blue light organic electroluminescent device examples 2-20 by replacing C1 in device example 1 with the host materials shown in the examples of Table 2 respectively.

[0120] Device Comparative Examples 1-10 Using the above method, the compounds described in the comparative examples in Table 2 are made into organic electroluminescent devices, specifically referring to making blue light organic electroluminescent device comparative examples 1-10 by replacing C1 in device example 1 with the host materials shown in the comparative examples of Table 2 respectively.

[0121] The above-described OLED devices were tested by standard methods. For this purpose, at a current density of J = 10 mA / cm 2 , the driving voltage and luminous efficiency of the organic electroluminescent device were determined. LT97 refers to the time when the luminous brightness of the fabricated blue-light device drops to 97% of its initial value L 2 after a time LT97 when the device operates at J = 20 mA / cm 0 .

[0122] The test instruments and methods for testing the performance of the above-described example and comparative example OLED devices are as follows: The luminous efficiency C.E (cd / A) and color coordinates (CIEy) were tested using a spectral scanner PhotoResearch PR-635; Current density and turn-on voltage: tested using a digital source meter Keithley 2400; The luminous efficiency of blue-light devices is greatly affected by chromaticity. In the industry, the BI value is generally used as the basis for the efficiency of blue-light devices. BI (Blue index) is obtained by dividing the luminous efficiency C.E (cd / A) by the color coordinates (CIEy); Lifetime test: using a silicon optoelectronic OLED device lifetime test system.

[0123] The performance test results of the above devices are listed in Table 2.

[0124] Table 2 Performance test results of blue-light devices

[0125] It can be seen from the above device results that the test lifetime of the materials of the present invention on the device reaches a level basically equivalent to that of Comparative Example 1 of the device, and is significantly better than Comparative Examples 2-8 of the device. This is because the present invention introduces aryl substituents (i.e., Ar 2 and Ar 3), a special molecular structure is formed. Taking C3 as an example, on the one hand, the carbon-hydrogen bond of the naphthalene fragment on the relatively weak naphthobenzofuran becomes a more stable carbon-carbon bond after being substituted by an aryl group. On the other hand, the special spatial three-dimensional structure can improve the carrier transport, reduce the probability of polarons staying on a single molecule in the device, and reduce the probability of interactions between polarons, excitons, carriers, etc. Therefore, the quenching and deterioration of the host material during the operation of the device are reduced, thereby improving the device life while ensuring high efficiency. More significantly, as shown in Table 1, due to the steric hindrance of the aryl group increasing the molecular rigidity, the recombination energy of the carriers is reduced, and the carrier transport is accelerated, thereby improving the voltage performance of the present invention in the device. Compared with device comparative examples 9-10, although these two comparative examples have a relatively small recombination energy due to structural factors and achieve a voltage reduction effect similar to that of the present invention, due to poor stability, they may exhibit relatively low efficiency and life due to material deterioration, quenching, etc.

[0126] Dual-host device Example 21 Similar to the preparation method of Device Example 1, the difference is that when preparing the light-emitting layer, a mixture of Compound C3, Compound BHB01, and Compound BD01 provided by the present invention is vacuum-deposited with a thickness of 20 nm to form the light-emitting layer, where BHB01 is used as the first host material, Compound C3 is used as the second host material, and BD01 is used as the guest material, and the mass ratio of the three materials is 58:40:2 in sequence; the rest is the same as the preparation method of Device Example 1.

[0127] Dual-host device Comparative Example 11 Similar to the preparation method of Device Example 1, the difference is that when preparing the light-emitting layer, a mixture of Compound DB10, Compound BHB01, and Compound BD01 provided by the present invention is vacuum-deposited with a thickness of 20 nm to form the light-emitting layer, where BHB01 is used as the first host material, Compound DB10 is used as the second host material, and BD01 is used as the guest material, and the mass ratio of the three materials is 58:40:2 in sequence; the rest is the same as the preparation method of Example 1.

[0128] Other molecular structural formulas that may be used in the dual-host device are as follows:

[0129] The above-mentioned OLED devices are tested by standard methods. For this purpose, at a current density of J = 10 mA / cm 2 the driving voltage and luminous efficiency of the organic electroluminescent device are determined. LT97 refers to the time when the prepared blue-light device operates at J = 20 mA / cm 2 and the luminous brightness drops to 97% of its initial value L 0 after time LT97.

[0130] The test instruments and methods for testing the performance of the above-mentioned example and comparative example OLED devices are as follows: The luminous efficiency C.E (cd / A) and color coordinates (CIEy) are tested using a spectral scanner PhotoResearch PR-635; Current density and turn-on voltage: tested using a digital source meter Keithley 2400; The luminous efficiency of blue light devices is greatly affected by chromaticity. In the industry, the BI value is generally used as the basis for the efficiency of blue light devices. BI (Blue index) is obtained by dividing the luminous efficiency C.E (cd / A) by the color coordinates (CIEy); Lifetime test: using a silicon photovoltaic OLED device lifetime test system.

[0131] The performance test results of the above devices are listed in Table 3.

[0132] Table 3

[0133] It can be seen from the data in Table 3 above that the materials of the present invention can also be used in double-host devices. By combining with polycyclic hosts with different charge transport characteristics, the carrier recombination probability can be increased, and thus the luminous efficiency of the device can be significantly improved; while DB10, which also adopts the biphenyl substitution scheme, has a small difference in the recombination energy of holes and electrons, and there is no significant difference in the charge transport characteristics of the two carriers. After combining with polycyclic hosts, there is no significant improvement in carrier recombination and the efficiency cannot be significantly increased.

[0134] Example 22 of double-emitting layer device Similar to the preparation method of Device Example 1, the difference is that when preparing the light-emitting layer, a mixture of compound BHA01 and compound BD01 is vacuum deposited with a thickness of 5 nm to form the first light-emitting layer, where compound BHA01 is used as the first host material and compound BD01 is used as the guest material, and the mass ratio of compound BHA01 to compound BD01 is 97:3; on the above first light-emitting layer, a mixture of compound C3 and compound BD01 is vacuum deposited with a thickness of 15 nm to form the second light-emitting layer, where compound C3 is used as the second host material and compound BD01 is used as the guest material, and the mass ratio of compound C3 to compound BD01 is 98:2 in sequence; the first light-emitting layer is adjacent to the light-emitting auxiliary layer, and the second light-emitting layer is adjacent to the hole blocking layer. The rest is the same as the preparation method of Example 1. For the device structure, see Figure 5 .

[0135] Comparative Example 12 of double-host device Similar to the preparation method of Device Example 1, the difference is that when preparing the light-emitting layer, a mixture of Compound BHA01 and Compound BD01 is vacuum deposited with a thickness of 5 nm to form the first light-emitting layer, where Compound BHA01 is used as the first host material and Compound BD01 is used as the guest material, and the mass ratio of Compound BHA01 to Compound BD01 is 97:3; on the above first light-emitting layer, a mixture of Compound DB10 and Compound BD01 is vacuum deposited with a thickness of 15 nm to form the second light-emitting layer, where Compound DB10 is used as the second host material and Compound BD01 is used as the guest material, and the mass ratio of Compound DB10 to Compound BD01 is 98:2 in sequence; the first light-emitting layer is adjacent to the light-emitting auxiliary layer, the second light-emitting layer is adjacent to the hole-blocking layer, and the rest is the same as the preparation method of Example 1. Other molecular structural formulas used in the double light-emitting layer device are as follows:

[0136] The above-mentioned OLED device is tested by standard methods. For this purpose, at a current density of J = 10 mA / cm 2 the driving voltage and luminous efficiency of the organic electroluminescent device are determined. LT97 refers to the time when the prepared blue light device operates at J = 20 mA / cm 2 and the luminous brightness drops to 97% of its initial value L 0 after time LT97.

[0137] The test instruments and methods for testing the performance of the above-mentioned Example and Comparative Example OLED devices are as follows: The luminous efficiency C.E (cd / A) and color coordinates (CIEy) are tested using a spectral scanner PhotoResearch PR-635; Current density and turn-on voltage: tested using a digital source meter Keithley 2400; The luminous efficiency of blue light devices is greatly affected by chromaticity. In the industry, the BI value is generally used as the basis for the efficiency of blue light devices. BI (Blue index) is obtained by dividing the luminous efficiency C.E (cd / A) by the color coordinates (CIEy); Lifetime test: using a silicon optoelectronic OLED device lifetime test system.

[0138] The performance test results of the above devices are listed in Table 4.

[0139] Table 4

[0140] As can be seen from the above devices, the materials of the present invention can also be used in double-emitting layer devices. The first emitting layer in the double-emitting layer is responsible for carrier recombination, and the second emitting layer is responsible for triplet-triplet fusion (TTF), thereby improving the luminescence efficiency. Due to the unique molecular structure of the present invention, such as Figure 2 the molecular conformation of C3 in it, the substituted phenyl group has a certain overlap with the anthracene nucleus, which is beneficial to the TTF process and thus significantly improves the luminescence efficiency.

[0141] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is impossible to enumerate all the implementation manners here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. An organic electroluminescent compound, characterized in that: The organic electroluminescent compound is selected from the general structure shown in the following formula I: I； in, Ar1 is selected from any one or more of a substituted or unsubstituted aryl group having 6 to 60 carbon atoms, a substituted or unsubstituted condensed ring aryl group having 10 to 60 carbon atoms, and a substituted or unsubstituted condensed ring heteroaryl group having 8 to 60 carbon atoms. When Ar1 has a substituent, the substituent is selected from deuterium or phenyl. Ar4 is selected from one of the structures shown in Formula II-1 to Formula II-4: II-1、 II-2、 II-3、 II-4; Ar2 and Ar3 are each independently selected from any one of deuterated or non-deuterated phenyl, deuterated or non-deuterated naphthyl; D represents deuterium, and represents a bonding site with anthracene in formula I; n1 is selected from 0 or 8, n2, n4, n5 are each independently selected from 0 or 6, n3 is selected from 0 or 3, and n6 is selected from 0 or 4.

2. The organic electroluminescent compound according to claim 1, characterized in that The aryl group is selected from any one of phenyl, biphenyl, dimethylfluorenyl, diphenylfluorenyl and spirofluorenyl.

3. The organic electroluminescent compound according to claim 1, characterized in that The condensed ring aromatic group is selected from any one of naphthyl, phenanthrenyl, pyrenyl, benzanthryl, triphenylenyl, chrysene, and fluoranthenyl.

4. The organic electroluminescent compound according to claim 1, characterized in that The heteroatom in the fused ring heteroaryl group is selected from any one of oxygen, nitrogen and silicon.

5. The organic electroluminescent compound according to claim 1, characterized in that The fused ring heteroaryl group is selected from one of the following structures: 。 6. The organic electroluminescent compound according to claim 1, characterized in that The Ar2 and Ar3 are selected from phenyl.

7. The organic electroluminescent compound according to claim 1, characterized in that The Ar1 is selected from phenyl.

8. The organic electroluminescent compound according to claim 1, characterized in that The organic electroluminescent compound is selected from one of the structures shown below: 。 9. An organic electroluminescent device, characterized in that: It comprises an anode, a hole transport region, a light-emitting layer, an electron transport region, and a cathode which are sequentially arranged on a substrate; wherein the light-emitting layer comprises one or more organic electroluminescent compounds as described in any one of claims 1 to 8.

10. The organic electroluminescent device according to claim 9, characterized in that: The light-emitting layer comprises a host material and a guest material, wherein the host material comprises one or more organic electroluminescent compounds according to any one of claims 1 to 8.

11. The organic electroluminescent device according to claim 9, characterized in that: The light-emitting layer comprises a first host material, a second host material and a guest material, wherein the first host material is selected from the compound shown in the following formula III, and the second host material comprises one or more organic electroluminescent compounds according to any one of claims 1 to 8: III; Ar5 is selected from any one of an aryl group having 6 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms substituted with benzene, a condensed ring aryl group having 10 to 30 carbon atoms, and a condensed ring aryl group having 10 to 30 carbon atoms substituted with benzene; Ar6 is selected from an aryl group having 6 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms substituted with benzene, a condensed ring aryl group having 10 to 30 carbon atoms, a condensed ring aryl group having 10 to 30 carbon atoms substituted with benzene, or 2-dibenzofuran.

12. The organic electroluminescent device according to claim 9, characterized in that: The light-emitting layer comprises a first light-emitting layer located above the hole transport region and a second light-emitting layer located above the first light-emitting layer, wherein the first light-emitting layer comprises a first host material and a guest material, and the first host material is selected from the compound represented by the following formula IV: The second light-emitting layer comprises a second host material and a guest material, and the second host material comprises one or more organic electroluminescent compounds according to any one of claims 1 to 8; IV; Ar7 is selected from any one of H, an aryl group having 6 to 30 carbon atoms, and a condensed ring aryl group having 10 to 30 carbon atoms; Ar8 is selected from any one of H, an aryl group having 6 to 30 carbon atoms, and a condensed ring aryl group having 10 to 30 carbon atoms; L is selected from one of phenyl and biphenyl.

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