An organic electroluminescence compound having a hole-blocking function

Abstract

The application belongs to the field of organic photoelectric materials, and particularly relates to an organic electroluminescent compound with a hole blocking function, a preparation method thereof, and an organic electroluminescent device prepared by using the compound as a hole blocking layer material. The compound has a moderate evaporation temperature, a relatively high glass transition temperature, good thermal stability, and a relatively suitable HOMO / LUMO value, and can be used in a hole blocking layer of an OLED device. The prepared device has the characteristics of high efficiency, low working voltage, and long service life.

Description

Technical Field

[0001] This invention belongs to the field of organic optoelectronic materials, and more specifically relates to an organic electroluminescent compound with hole blocking function, its preparation method, and an organic electroluminescent device prepared by using the compound as a hole blocking layer material. Background Technology

[0002] Organic light-emitting diode (OLED) devices typically consist of multiple layers of organic materials, such as a hole injection layer (HIL), a hole transport layer (HTL), an electron blocking layer (EBL), a light-emitting layer, and an electron injection layer (EIL). In OLED devices, when a voltage is applied between the anode and cathode, holes from the anode and electrons from the cathode are injected into the organic material layer. The resulting excitons migrate to the ground state, producing light with a specific wavelength.

[0003] Research on electron transport layer / hole blocking layer materials is relatively lagging behind. Electron transport layer / hole blocking layer materials need to have suitable HOMO / LUMO values ​​so that the injection barrier can be smaller and the driving voltage can be reduced. Some materials cannot effectively match the HOMO / LUMO of adjacent functional layer materials due to their large band gap, which makes it impossible to fully utilize energy and the injection barrier is too high, resulting in problems such as high driving voltage and low efficiency of the device.

[0004] For OLED materials, the glass transition temperature (Tg), sublimation temperature (Ts), and evaporation temperature are involved. The glass transition temperature (Tg) is an inherent property of a single material. The concept of sublimation temperature is somewhat ambiguous; sometimes it refers to the operating temperature at which the sublimation process occurs during the purification of OLED materials. However, it usually refers to the temperature at which the material begins to sublimate under a set vacuum level. The latter, the sublimation temperature, is generally considered an inherent property of the single material. The sublimation temperature referred to in this invention refers to the latter, that is, the temperature at which the material begins to sublimate under a set vacuum level. The evaporation temperature is above the sublimation temperature and is set during the production process according to actual needs. That is, it is not an inherent property of the material but can be adjusted. Especially when a faster evaporation rate is required, the evaporation temperature can be increased.

[0005] When materials are used in the fabrication of OLED devices, the sublimation temperature of the materials needs to be higher than the glass transition temperature. Otherwise, during the fabrication process, the surface of the materials is prone to wrinkles and unevenness after evaporation, resulting in charge accumulation, which significantly reduces the lifespan and efficiency of the devices.

[0006] The "moderate vapor deposition temperature" in this invention refers to a temperature that is as low as possible, provided that the material's sublimation temperature is higher than its glass transition temperature (Tg). Higher sublimation temperatures can easily cause thermal decomposition of the material during actual vapor deposition, leading to reduced device lifespan, decreased efficiency, and increased drive voltage.

[0007] The thermal stability of OLED materials manifests in two aspects. First, when fabricating OLED devices using the vapor deposition method, the deposition temperature is typically above 250 degrees Celsius, and in some cases can reach 400 degrees Celsius, raising the possibility of thermal decomposition of the material. Second, on OLED panel mass production lines, it is often necessary to continuously heat the OLED material stored in the reactor at the actual deposition temperature for extended periods, sometimes exceeding 150 hours or even longer, under which the material may age and decompose. Research indicates that these two types of thermal stability are not uniform; some materials do not meet the required thermal stability under prolonged heating conditions.

[0008] Increasing the glass transition temperature appropriately, without significantly affecting the evaporation temperature, is beneficial. A proper increase in the glass transition temperature can improve the film-forming stability of the material during evaporation, thereby extending device lifespan.

[0009] In the material systems corresponding to different devices, it is generally required in the field that the hole blocking layer has an HHOMO / LUMO value that matches the adjacent light-emitting layer and electron transport layer, which can improve efficiency and reduce driving voltage.

[0010] Therefore, in light of the above problems, developing an organic electroluminescent compound with hole-blocking function, which has a moderate evaporation temperature, a relatively high glass transition temperature, and good thermal stability, so that the organic electroluminescent device prepared from it has the advantages of low driving voltage, high efficiency, and long lifespan, is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0011] This invention provides an organic electroluminescent compound with hole-blocking function, which has a moderate evaporation temperature, a relatively high glass transition temperature, and good thermal stability. It can be used as a hole-blocking layer in OLED devices, and the prepared devices have the technical effects of high efficiency, low operating voltage, and long life.

[0012] An organic electroluminescent compound with hole-blocking function has the structure shown in Formula I:

[0013]

[0014] In Formula I:

[0015] Z1-Z3 are C or N atoms, with at least two of them being N; preferably, all of Z1-Z3 are N atoms.

[0016] R1 is a C1-C4 alkyl group; it can be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or tert-butyl; methyl is preferred. The alkyl group can be deuterated in any number of ways.

[0017] R2-R3 are independently selected from substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted biphenyl, substituted or unsubstituted terphenyl, substituted or unsubstituted pyridyl.

[0018] Ar1 and Ar2 are independently selected from substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted biphenyl, substituted or unsubstituted triphenyl, and substituted or unsubstituted dibenzofuranyl.

[0019] It is particularly important to note that Ar1 and Ar2 explicitly exclude groups with hole transport capabilities, such as dibenzothiophene, carbazole, and spirodifluorene.

[0020] m, n, p, and q independently represent integers of 0 or 1; and m + n ≥ 1; p + q ≥ 1;

[0021] R4-R5 are independently selected from substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted biphenyl, and substituted or unsubstituted pyridyl.

[0022] Furthermore, R1 in the compound is a methyl group.

[0023] Furthermore, in the compound, Z1-Z3 are all N atoms.

[0024] Furthermore, R4 is hydrogen, and R5 is a substituted or unsubstituted phenyl, a substituted or unsubstituted naphthyl, a substituted or unsubstituted biphenyl, or a substituted or unsubstituted pyridyl.

[0025] The term “substitution” as used herein refers to substitution by one, two or more substituents selected from the following: hydrogen, deuterium, cyano, C1-C10 alkyl, C3-C10 cycloalkyl, 3-10 heterocyclic alkyl, wherein the heteroatom is selected from oxygen, nitrogen, and sulfur; C6-C20 aryl, 3-10 heteroaryl, wherein the heteroatom is selected from oxygen, nitrogen, and sulfur;

[0026] In particular, the substituents of the pyridyl group are preferably cyano and / or phenyl.

[0027] The compound is further specified as one of the following specific compounds:

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037] Preparation method

[0038] This invention also provides a method for preparing an organic electroluminescent compound, specifically, the compound is prepared by coupling its constituent components via a Suzuki reaction. The general reaction formula is as follows:

[0039]

[0040] In the general formula, one of X and Y is a halogen, preferably I, Br, or Cl; the other is a boron-containing group suitable for the SUZUKI reaction; preferably a boric acid group or a borate ester group, specifically B(OH)2, pinacol borate ester group, etc.

[0041] Organic electroluminescent devices

[0042] The present invention also provides an organic electroluminescent device, the organic electroluminescent device comprising an anode, a cathode, and a multilayer organic film layer located between the anode and the cathode, the multilayer organic film layer comprising at least a light-emitting layer and a hole-blocking layer, wherein the hole-blocking layer comprises the organic electroluminescent compound.

[0043] Display panel

[0044] The present invention also provides a display panel comprising an organic electroluminescent device, the organic electroluminescent device comprising an anode, a cathode, and a multilayer organic film layer located between the anode and the cathode, the multilayer organic film layer comprising at least an emissive layer (EML) and an electron transport layer (ETL) and / or a hole blocking layer (HBL), wherein the electron transport layer or hole blocking layer comprises one or more of the compounds described in the present invention.

[0045] The luminescent layer may include luminescent materials known in the art. Further, the luminescent material may include a host material and a dopant material. The host material may be selected from host luminescent materials known in the art and / or any one or more compounds described in this invention. The dopant material may be selected from fluorescent luminescent materials, phosphorescent materials, or thermally activated delayed fluorescence (TADF) luminescent materials known in the art, depending on the luminescence principle; and from blue, green, or red luminescent materials known in the art, depending on the luminescence color. The host material known in the art can be selected and combined according to the luminescence principle and luminescence color of the guest material; it may be a fluorescent host material, a unipolar host material, a bipolar host material, a dual host material, etc., and may be a blue light host material, a green light host material, or a red light host material.

[0046] In the display panel of the present invention, the multilayer organic film may further include other functional layers. As an example, other functional layers may include a hole blocking layer (HBL). For instance, the hole blocking layer is laminated between the light-emitting layer and the electron transport layer. In some embodiments, the hole blocking material (HBM) of the hole blocking layer (HBL) may be selected from HBMs known in the art (e.g., BCP, TPBi, TmPyPB, DPEPO, TAZ, etc.) and / or any one or more of the compounds described in the present invention.

[0047] In some embodiments, other functional layers may also include a hole injection layer (HIL), a hole transport layer (HTL), an electron blocking layer (EBL), a light-emitting auxiliary layer (prime layer), and an electron injection layer (EIL). The materials of each layer (such as hole injection material HIM, hole transport material HTM, electron blocking material EBM, and electron injection material EIM) may be selected from corresponding materials known in the art.

[0048] Display device

[0049] This invention provides a display device including the display panel described herein. Examples of display devices include, but are not limited to, mobile phones, computers, televisions, smartwatches, smart cars, VR or AR headsets, etc., and this invention does not specifically limit them.

[0050] Beneficial effects

[0051] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:

[0052] This invention provides an organic electroluminescent compound with hole-blocking function. It has a moderate evaporation temperature, a relatively high glass transition temperature, good thermal stability, and a suitable HOMO / LUMO value, which can be used as a hole-blocking layer in OLED devices. The prepared devices have the characteristics of high efficiency, low operating voltage, and long lifespan. Attached Figure Description

[0053] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0054] Figure 1 The attached figure is the 1H NMR spectrum of compound 66, which is the synthetic example 3 of this invention. Detailed Implementation

[0055] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] Synthesis Example 1 - Compound 13

[0057] The raw material a-13 needs to be prepared by the following reaction process:

[0058]

[0059] Under nitrogen atmosphere, raw materials a-13-1 (1.0 eq) and a-13-2 (1.1 eq) were added to a reaction flask, followed by the addition of a mixed solution of toluene, ethanol, and water (V:V:V = 2:1:1). The mixture was purged three times. Under nitrogen protection, tetrakis(triphenylphosphine)palladium (0.01 eq) was added, and the mixture was heated to 90 °C and refluxed for 14 hours. The reaction was detected by thin-layer chromatography. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered with diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with dichloromethane. The organic phases were combined and concentrated. The intermediate 1 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:10).

[0060] Under nitrogen atmosphere, raw material C-13-1 (1.0 eq) was dissolved in tetrahydrofuran (5.0 eq), and the solution was cooled to -70°C using liquid nitrogen. Next, n-butyllithium (1.1 eq) was slowly injected into the solution, and the mixture was stirred for 40 min. Subsequently, intermediate 1 (1.1 eq) dissolved in (5.0 eq) tetrahydrofuran was slowly injected into the reaction vessel. The reactor was heated to room temperature, and the mixture was then stirred for 12 h. After the reaction was complete, the reactants were poured into an aqueous ammonium chloride solution, the organic layer was separated, the solvent was removed, and the mixture was dried to obtain intermediate 2.

[0061] Intermediate 2 (1.0 eq) was dissolved in dry DCM and stirred at 0°C for 30 minutes. Then, MSA (5.0 eq) was added dropwise. After the addition was complete, the mixture was slowly raised to room temperature, and the reaction was continued for 5 hours. After the reaction was complete, sodium bicarbonate was added to quench the reaction. The resulting mixture was then extracted with dichloromethane to obtain the organic phase, which was then treated with anhydrous magnesium sulfate to remove water. The residue obtained was separated and purified by rapid column chromatography to give compound a-13.

[0062] Preparation of compound 13:

[0063]

[0064] Under nitrogen protection, starting materials a-13 (1.0 eq) and b-13 (1.1 eq) were stirred evenly in 280 mL of a mixed solvent of toluene, ethanol, and water (volume ratio 2:1:1). Then, X-Phos (0.05 eq), palladium acetate (Pd(OAc)2) (0.05 eq), and cesium carbonate (2.0 eq) were added. After thorough stirring, the mixture was heated to 90 °C and stirred for 10 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered with diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The organic phases were combined and dried with anhydrous magnesium sulfate. The solvent was removed using a rotary evaporator to obtain compound 13. The yield of compound 13 was calculated to be 59.2%.

[0065] The obtained compound 13 was analyzed, and the results are as follows:

[0066] HPLC purity: >99.6%.

[0067] MS(ESI,m / Z):[M+H]+: 715.58

[0068] Elemental analysis:

[0069] The theoretical values ​​are: C, 88.92; H, 5.21; N, 5.87.

[0070] The test values ​​are: C, 87.88; H, 5.51; N, 6.09.

[0071] Synthesis Example 2 - Compound 43

[0072] The raw material a-43 needs to be prepared by the following reaction process:

[0073]

[0074] Under nitrogen atmosphere, raw materials a-43-1 (1.0 eq) and a-43-2 (1.1 eq) were added to a reaction flask, followed by the addition of a mixed solution of toluene, ethanol, and water (V:V:V = 2:1:1). The mixture was purged three times. Under nitrogen protection, tetrakis(triphenylphosphine)palladium (0.01 eq) was added, and the mixture was heated to 90°C and refluxed for 14 hours. The reaction was detected by thin-layer chromatography. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered with diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with dichloromethane. The organic phases were combined and concentrated. Intermediate 1 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:10).

[0075] Under nitrogen atmosphere, raw material C-43-1 (1.0 eq) was dissolved in tetrahydrofuran (5.0 eq), and the solution was cooled to -70°C using liquid nitrogen. Next, n-butyllithium (1.1 eq) was slowly injected into the solution, and the mixture was stirred for 40 min. Subsequently, intermediate 1 (1.1 eq) dissolved in (5.0 eq) tetrahydrofuran was slowly injected into the reaction vessel. The reactor was heated to room temperature, and the mixture was then stirred for 12 h. After the reaction was complete, the reactants were poured into an aqueous ammonium chloride solution, the organic layer was separated, the solvent was removed, and the mixture was dried to obtain intermediate 2.

[0076] Intermediate 2 (1.0 eq) was dissolved in dry DCM and stirred at 0°C for 30 minutes. Then, MSA (5.0 eq) was added dropwise. After the addition was complete, the mixture was slowly raised to room temperature, and the reaction was continued for 5 hours. After the reaction was complete, sodium bicarbonate was added to quench the reaction. The resulting mixture was then extracted with dichloromethane to obtain the organic phase, which was then treated with anhydrous magnesium sulfate to remove water. The residue obtained was separated and purified by rapid column chromatography to give compound a-43.

[0077] Preparation of compound 43:

[0078]

[0079] Under nitrogen protection, starting materials a-43 (1.0 eq) and b-43 (1.1 eq) were stirred evenly in 280 mL of a mixed solvent of toluene, ethanol, and water (volume ratio 2:1:1). X-Phos (0.05 eq), palladium acetate (Pd(OAc)2) (0.05 eq), and cesium carbonate (2.0 eq) were then added. After thorough stirring, the mixture was heated to 90 °C and stirred for 10 h. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered using diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The organic phases were combined and dried using anhydrous magnesium sulfate. The solvent was removed using a rotary evaporator to obtain compound 43. The yield of compound 43 was calculated to be 58.4%.

[0080] The obtained compound 43 was analyzed, and the results are as follows:

[0081] HPLC purity: >99.6%.

[0082] MS(ESI,m / Z):[M+H]+: 815.59.

[0083] Elemental analysis:

[0084] The theoretical values ​​are: C, 89.79; H, 5.06; N, 5.15.

[0085] The test values ​​are: C, 89.01; H, 5.48; N, 5.52.

[0086] Synthesis Example 3 - Compound 66

[0087] The raw material a-66 needs to be prepared by the following synthetic route:

[0088]

[0089] Under nitrogen atmosphere, raw materials a-66-1 (1.0 eq) and a-66-2 (1.1 eq) were added to a reaction flask, followed by the addition of a mixed solution of toluene, ethanol, and water (V:V:V = 2:1:1). The mixture was purged three times. Under nitrogen protection, tetrakis(triphenylphosphine)palladium (0.01 eq) was added, and the mixture was heated to 90°C and refluxed for 14 hours. The reaction was detected by thin-layer chromatography. After the reaction was completed, the temperature was slightly lowered, and the mixture was filtered with diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with dichloromethane. The organic phases were combined and concentrated. Intermediate 1 was purified by column chromatography using a mixed solution of dichloromethane and petroleum ether (V:V = 1:10).

[0090] Under nitrogen atmosphere, raw material C-66-1 (1.0 eq) was dissolved in tetrahydrofuran (5.0 eq), and the solution was cooled to -70°C using liquid nitrogen. Next, n-butyllithium (1.1 eq) was slowly injected into the solution, and the mixture was stirred for 40 min. Subsequently, intermediate 1 (1.1 eq) dissolved in (5.0 eq) tetrahydrofuran was slowly injected into the reaction vessel. The reactor was heated to room temperature, and the mixture was then stirred for 12 h. After the reaction was complete, the reactants were poured into an aqueous ammonium chloride solution, the organic layer was separated, the solvent was removed, and the mixture was dried to obtain intermediate 2.

[0091] Intermediate 2 (1.0 eq) was dissolved in dry DCM and stirred at 0°C for 30 minutes. Then, MSA (5.0 eq) was added dropwise. After the addition was complete, the mixture was slowly raised to room temperature, and the reaction was continued for 5 hours. After the reaction was complete, sodium bicarbonate was added to quench the reaction. The resulting mixture was then extracted with dichloromethane to obtain the organic phase, which was then treated with anhydrous magnesium sulfate to remove water. The residue obtained was separated and purified by rapid column chromatography to give compound a-66.

[0092] Preparation of compound 66:

[0093]

[0094] Under nitrogen protection, starting materials a-66 (1.0 eq) and b-66 (1.1 eq) were stirred in 280 mL of a mixed solvent of toluene, ethanol, and water (volume ratio 2:1:1). X-Phos (0.05 eq), palladium acetate (Pd(OAc)2) (0.05 eq), and cesium carbonate (2.0 eq) were then added. After thorough stirring, the mixture was heated to 90 °C and stirred for 10 h. After the reaction was complete, the temperature was slightly lowered, and the mixture was filtered through diatomaceous earth to remove salts and catalysts. The filtrate was cooled to room temperature and washed three times with water, retaining the organic phase. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were dried using anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator to obtain compound 66. The yield of compound 66 was calculated to be 60.1%.

[0095] The obtained compound 66 was analyzed, and the results are as follows:

[0096] HPLC purity: >99.6%.

[0097] MS(ESI,m / Z):[M+H]+: 715.56.

[0098] Elemental analysis:

[0099] The theoretical values ​​are: C, 88.92; H, 5.21; N, 5.87.

[0100] The test values ​​are: C, 88.17; H, 5.60; N, 6.12.

[0101] Examples 4-30: The following compounds were synthesized using the methods described in Examples 1-3. The theoretical and measured mass spectrometry values ​​are shown in Table 1 below:

[0102] Example compound Mass spectrometry test values Example 4 1 715.46 Example 5 3 791.58 Example 6 6 805.61 Example 7 8 805.55 Example 8 10 881.67 Example 9 14 867.58 Example 10 18 805.62 Example 11 20 805.49 Example 12 33 805.39 Example 13 34 867.78 Example 14 37 715.56 Example 15 42 805.56 Example 16 47 867.69 Example 17 52 805.44 Example 18 58 715.62 Example 19 65 716.58 Example 20 69 881.51 Example 21 74 917.63 Example 22 78 855.57 Example 23 83 917.61 Example 24 87 891.52 Example 25 94 981.66 Example 26 98 993.72 Example 27 101 931.63 Example 28 104 855.54 Example 29 106 1007.41 Example 30 108 1069.51

[0103] Device Examples

[0104] The device embodiments of the present invention use the compound of the present invention as a hole blocking layer material, as detailed below:

[0105] Device Example HB1: Fabrication of an organic electroluminescent device containing compound 13

[0106] a. ITO Anode: A 150nm thick ITO (Indium Tin Oxide)-Ag-ITO (Indium Tin Oxide) glass substrate is cleaned twice in distilled water, ultrasonically washed for 30 minutes, then repeatedly cleaned twice with distilled water, ultrasonically washed for 10 minutes. After cleaning, it is baked in a vacuum oven at 220℃ for 2 hours. After baking, it is cooled before use. Using this substrate as the anode, a vapor deposition process is performed to deposit other functional layers sequentially on it.

[0107] b. HIL (Hole Injection Layer): The evaporation rate of the hole injection layer material HT-1 and P-dopant was determined by vacuum evaporation, and their chemical formulas are shown below. The evaporation rate ratio of HT-1 to P-dopant was 98:2, and the thickness was 10 nm.

[0108] c. HTL (Hole Transport Layer): At the evaporation rate, HT-1 of 110 nm was vacuum-deposited on the hole injection layer as a hole transport layer.

[0109] d. Light-emitting auxiliary layer: The evaporation rate was such that 10 nm EB-1 was vacuum-deposited on the hole transport layer as a light-emitting auxiliary layer;

[0110] e. EML (Emitting Layer): Then, on the above-mentioned emitting auxiliary layer, with... The evaporation rate was determined by vacuum evaporation of a host material and a dopant material with a thickness of 20 nm as the light-emitting layer. The chemical formulas of the host and dopant are shown below. The evaporation rate ratio of the host to the dopant is 98:2.

[0111] f. HBL (Hole Blocking Layer): with The evaporation rate was such that compound 13, provided in the above embodiment, was vacuum-deposited as a hole-blocking layer at a depth of 30 nm on the light-emitting layer:

[0112] g. ETL (Electron Transport Layer): At a certain evaporation rate, a 30nm ET layer was vacuum-deposited on top of the hole blocking layer as an electron transport layer.

[0113] h, EIL (Electron Injection Layer): with The evaporation rate was such that a 1.0 nm metallic Yb film was deposited, forming an electron injection layer.

[0114] i. Cathode: with The evaporation rate ratio of magnesium and silver at 18nm was 1:9, resulting in an OLED device.

[0115] j. Optical extraction layer: with The evaporation rate was adjusted to vacuum-deposit a 70nm thick CPL layer on the cathode as a light extraction layer. The deposited substrate was then encapsulated. First, a UV adhesive was applied to the cleaned cover plate using a coating machine. Then, the coated cover plate was moved to the lamination section, and the evaporated substrate was placed on top of the cover plate. Finally, the substrate and cover plate were laminated using a bonding machine, simultaneously curing the UV adhesive under UV light.

[0116]

[0117] Device Examples 2 to 30 refer to the preparation method of Device Example 1, but replace compound 13 with compounds 43, 66, 1, 3, 6, 8, 10, 14, 18, 20, 33, 34, 37, 42, 47, 52, 58, 65, 69, 74, 78, 83, 87, 94, 98, 101, 104, 106, and 108 as hole blocking layers to prepare the corresponding organic electroluminescent devices.

[0118] Device comparison example:

[0119] The only difference between the preparation methods of Comparative Examples 1-2 and Device Example 1 is that the organic electroluminescent devices are prepared by evaporation using existing comparative compounds A and B instead of the hole blocking layer (compound 13) in Device Example 1.

[0120] The chemical structural formulas of compounds A and B are as follows:

[0121]

[0122] Device Implementation Data

[0123] At a brightness of 1000 nits, the driving voltage, luminous efficiency, BI value, and lifetime of the organic electroluminescent devices obtained in Device Examples 1 to 30 were characterized, and the test results are shown in Table 2 below:

[0124] Table 2 - Device Example Data When the Compounds of the Present Invention are Used as HB Materials

[0125]

[0126]

[0127] Note: In blue top-emitting devices, current efficiency is greatly affected by chromaticity. Therefore, the influence of chromaticity on efficiency is taken into account, and the ratio of luminous efficiency to CIEy is defined as the BI value, i.e., BI = (cd / A) / CIEy.

[0128] As shown in Table 2, compared with the existing organic electroluminescent devices provided in Comparative Examples 1-2, the organic electroluminescent devices prepared using the hole blocking material provided by the present invention in Examples 1-30 have improved luminous efficiency and lifetime while reducing the driving voltage.

[0129] As can be seen above, compared with comparative compounds A and B, the compounds of the present invention have the characteristics of moderate evaporation temperature, relatively high glass transition temperature, and good thermal stability. When applied to the hole blocking layer of OLED devices, they possess suitable HOMO / LUMO values, and the prepared devices exhibit high efficiency, low operating voltage, and long lifetime. Specifically, comparative compounds A and B are compounds from the applicant's prior application 2023108855929. These compounds can be used as ET materials or HB materials. Further research revealed that when HB materials are used in specific OLED device systems, they suffer from low glass transition temperature and excessively low LUMO, leading to a mismatch. To address these shortcomings, the present invention was developed. Compound 66 of the present invention is a parallel comparative example with comparative compounds A and B. The difference between compound 66 and comparative compound A is that a phenyl group is added to the bridging group between the triazine and fluorene, which not only prolongs the conjugated system but also increases the glass transition temperature, thereby improving lifetime. The difference between compound 66 and comparative compound B is that the benzene of the parent alkyl fluorene core has undergone phenyl substitution. As those skilled in the art will know, for triazine groups with electron transport capabilities, since the 9-position carbon atom of the parent is sp3 hybridized and does not participate in conjugation, phenyl substitution on the benzene of the fluorene core does not conjugate the system. However, phenyl substitution on the benzene of the fluorene core can adjust the LUMO value of the HB molecule, thereby improving efficiency and reducing the driving voltage.

[0130] Those skilled in the art will readily recognize that many modifications and variations can be made to this invention without departing from its spirit and scope. Therefore, it is contemplated that this invention covers the modifications and variations provided within the scope of the appended claims and their equivalents.

[0131] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0132] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An organic electroluminescent compound with hole-blocking function, having the structure shown in Formula I: In Formula I: Z1-Z3 are C or N atoms, and at least two of them are N; R1 can be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or tert-butyl; wherein R1 can be deuterated in any number of ways. R2-R3 are independently selected from substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted biphenyl, substituted or unsubstituted terphenyl, substituted or unsubstituted pyridyl. Ar1 and Ar2 are independently selected from substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted biphenyl, substituted or unsubstituted triphenyl, and substituted or unsubstituted dibenzofuranyl. m, n, p, and q independently represent integers of 0 or 1; and m + n ≥ 1; p + q ≥ 1; R4-R5 are independently selected from substituted or unsubstituted phenyl, substituted or unsubstituted naphthyl, substituted or unsubstituted biphenyl, substituted or unsubstituted pyridyl. The term "substitution" as used herein refers to substitution by one, two or more substituents selected from the following: cyano, C1-C10 alkyl, C3-C10 cycloalkyl, 3-10 heterocyclic alkyl, wherein the heteroatom is selected from oxygen, nitrogen, or sulfur; C6-C20 aryl, 3-10 heteroaryl, wherein the heteroatom is selected from oxygen, nitrogen, or sulfur.

2. The compound according to claim 1, characterized in that: R1 is replaced by any number of deuterates.

3. The compound according to claim 1, characterized in that: R1 is a methyl group.

4. The compound according to claim 1, characterized in that: Z1-Z3 are all N atoms.

5. The compound according to claim 1, characterized in that: R4 is hydrogen, and R5 is a substituted or unsubstituted phenyl, a substituted or unsubstituted naphthyl, a substituted or unsubstituted biphenyl, or a substituted or unsubstituted pyridyl.

6. The compound according to claim 1, characterized in that: It is one of the following specific compounds: 。 7. The method for preparing the compound according to claim 1, characterized in that: The components of the compound were prepared by coupling via the Suzuki reaction; the general reaction formula is as follows: In the general formula, one of X and Y is a halogen; the other is a boron-containing group applicable to the SUZUKI reaction. Z1-Z3, R1, R2-R3, Ar1, Ar2, m, n, p, q, and R4-R5 are as defined in claim 1.

8. The method as described in claim 7, characterized in that: The halogen is selected from I, Br, and Cl; the boron-containing group is a borate group or a borate ester group.

9. An organic electroluminescent device, the organic electroluminescent device comprising an anode, a cathode, and a multilayer organic film layer located between the anode and the cathode, the multilayer organic film layer comprising at least a light-emitting layer and a hole-blocking layer, wherein the hole-blocking layer comprises the organic electroluminescent compound of claim 1.

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