A cyan-modified compound with a dibenzo five-membered ring as a bridging structure and an organic electroluminescence device comprising the same

Abstract

The application discloses a cyano-modified compound with a diphenylbenzoquinone as a bridging structure and an organic electroluminescent device containing the same, and belongs to the technical field of semiconductor materials. The structure of the compound is shown in general formula (1). The compound has good stability and electron resistance, and has good electron injection and electron transport capacity. When the compound is used as an electron transport material of an organic electroluminescent device, the driving voltage of the device is significantly reduced, and the normal temperature life and high temperature life of the device are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor materials technology, and in particular to a cyano-modified compound with a dibenzo-pentacyclic ring as a bridging structure and an organic electroluminescent device containing the same. Background Technology

[0002] Organic light-emitting diodes (OLEDs) technology can be used to manufacture novel display products and lighting products, with a wide range of applications. OLEDs have a sandwich-like structure, consisting of electrode material layers and organic functional materials sandwiched between them. These various organic functional materials are stacked together according to their intended use to form the OLED. As a current-emitting device, when a voltage is applied to its two electrodes, and an electric field is applied to the positive and negative charges in the organic functional material layers, the positive and negative charges recombine in the light-emitting layer, thus generating organic electroluminescence.

[0003] Currently, OLED display technology has been applied in smartphones, tablets, televisions, and other fields. However, compared with the requirements of actual product applications, the luminous efficiency and lifespan of organic electroluminescent devices still need further improvement. In order to continuously improve the performance of organic electroluminescent devices, it is necessary to continuously research and innovate organic optoelectronic functional materials to create higher-performance organic optoelectronic functional materials.

[0004] Organic optoelectronic functional materials used in organic electroluminescent devices can be broadly classified into two categories based on their applications: charge injection and transport materials, and luminescent materials. Further, charge injection and transport materials can be categorized into electron injection materials, electron transport materials, electron blocking materials, hole injection materials, hole transport materials, and hole blocking materials. As electron transport materials, they require good carrier mobility and high glass transition temperature. In organic electroluminescent devices, electrons are injected from the cathode and then transported through the electron transport layer to the host material, where they recombine with holes to generate excitons. Therefore, improving the injection and transport capabilities of the electron transport layer helps reduce the device driving voltage and simultaneously achieves high electron-hole recombination efficiency. Thus, the electron transport layer is crucial, requiring high electron injection and transport capabilities, as well as high electron durability.

[0005] For device lifespan, the heat resistance and film stability of materials are also crucial. Materials with low heat resistance are prone to decomposition not only during material vapor deposition but also during device operation due to the heat generated, leading to material degradation. In cases of poor film phase stability, the material may also undergo rapid film crystallization, causing delamination of the organic film layer and resulting in device degradation. Therefore, materials with high heat resistance and good film stability are required.

[0006] With the increasing demand for improved performance in organic electroluminescent devices, the requirements for material properties are also rising. These materials need not only good stability but also high efficiency and lifespan at low driving voltages. However, current electron transport materials suffer from insufficient thermal stability and deficiencies in electron tolerance, leading to phase separation or decomposition during device operation and consequently, shorter device lifespans. Summary of the Invention

[0007] To address the aforementioned problems in the existing technology, the applicant of this invention provides a cyano-modified compound with a dibenzo-5-membered ring as a bridging structure and an organic electroluminescent device containing the compound. The compound of this invention has excellent electron injection and transport capabilities. When applied to organic electroluminescent devices, it can effectively reduce the device operating voltage and extend the device's lifespan at both room temperature and high temperature.

[0008] This invention provides a technical solution: a cyano-modified compound with a dibenzo-5-membered ring as a bridging structure, the structure of which is shown in general formula (1):

[0009]

[0010] In general formula (1), X represents an oxygen atom or a sulfur atom;

[0011] X1, X2, X3, X4, X5, and X6 are each independently represented as nitrogen atoms or CH; and at least one of X1-X3 is represented as a nitrogen atom, and at least one of X4-X6 is represented as a nitrogen atom.

[0012] R1, R2, R3, and R4 represent, independently, Ra-substituted or unsubstituted C6-C atoms. 30 Aryl, Ra-substituted or unsubstituted C2-C 30 Mixed aromatics;

[0013] L1 and L represent, independently, direct bonds, Rb-substituted bonds, or unsubstituted C6-C bonds, respectively. 30 arylene, Rb-substituted or unsubstituted C2-C 30 heteroaryl;

[0014] Ra and Rb are independently represented as cyano, deuterium, phenyl, cyano-substituted phenyl, naphthyl, or diphenyl;

[0015] At least one of R1, R2, R3, R4, L, and L1 is replaced by a cyano group;

[0016] Any hydrogen atom in the compound shown in general formula (1) can be replaced by a deuterium atom.

[0017] Furthermore, the structure of the compound is shown in any one of general formulas (2-1) to (2-6):

[0018]

[0019]

[0020] In general formulas (2-1) to (2-6), the meanings of X, X1, X2, X3, X4, X5, X6, R1, R2, R3, R4, L1, and L are the same as those in general formula (1) above.

[0021] Any hydrogen atom in the compounds shown in general formulas (2-1) to (2-6) can be replaced by a deuterium atom.

[0022] Furthermore, the structure of the compound is shown in any one of general formulas (3-1) to (3-15):

[0023]

[0024]

[0025] In general formulas (3-1) to (3-15), the meanings of X, R1, R2, R3, R4, L1, and L are the same as those in general formula (1) above;

[0026] In the compounds shown by general formulas (3-1) to (3-15), any hydrogen atom can be replaced by a deuterium atom.

[0027] Furthermore, at least one of R1, R2, R3, and R4 is substituted with a cyano group.

[0028] Furthermore, one or two of R1, R2, R3, and R4 are replaced by cyano groups.

[0029] Furthermore, the structure of the compound is shown in any one of general formulas (4-1) to (4-11):

[0030]

[0031] In general formulas (4-1) to (4-11), the meanings of X, X1, X2, X3, X4, X5, X6, R1, R2, R3, R4, L1, L, and Rb are the same as those in general formula (1) above.

[0032] In the compounds shown by general formulas (4-1) to (4-11), any hydrogen atom can be replaced by a deuterium atom.

[0033] Furthermore, R1, R2, R3, and R4 are each independently represented as Ra-substituted or unsubstituted phenyl, Ra-substituted or unsubstituted naphthyl, Ra-substituted or unsubstituted diphenyl, Ra-substituted or unsubstituted terphenyl, Ra-substituted or unsubstituted phenanthyl, Ra-substituted or unsubstituted pyridyl, Ra-substituted or unsubstituted pyrimidinyl, Ra-substituted or unsubstituted dibenzofuranyl, Ra-substituted or unsubstituted dibenzothiophenyl, Ra-substituted or unsubstituted carbazoleyl, and Ra-substituted or unsubstituted N-phenylcarbazoleyl.

[0034] Preferably, R1, R2, R3, and R4 are each independently represented as follows:

[0035]

[0036]

[0037] any one of them;

[0038] L1 and L are respectively independently represented as a direct bond, Rb-substituted or unsubstituted phenylene, Rb-substituted or unsubstituted diphenylene, Rb-substituted or unsubstituted terphenylene, Rb-substituted or unsubstituted tetraphenylene, Rb-substituted or unsubstituted naphthylene, Rb-substituted or unsubstituted phenanthrene, Rb-substituted or unsubstituted pyridylene, Rb-substituted or unsubstituted pyrimidinylene, Rb-substituted or unsubstituted dibenzofuranylene, Rb-substituted or unsubstituted dibenzothiophenylene, Rb-substituted or unsubstituted carbazolylene, and Rb-substituted or unsubstituted N-phenylcarbazolylene.

[0039] Preferably, L1 and L are each represented independently as follows:

[0040]

[0041]

[0042] any one of them;

[0043] The meanings of Ra and Rb are the same as those defined in claim 1.

[0044] Furthermore, the specific structure of the compound is any one of the following structures:

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064] The present invention also provides an organic electroluminescent device, comprising a substrate, a first electrode and a second electrode, wherein a multilayer organic thin film layer is provided between the first electrode and the second electrode, and the organic thin film layer contains the cyano-modified compound with a dibenzo five-membered ring as a bridging structure.

[0065] Preferably, the organic thin film layer includes a hole transport region thin film layer, a light emission region thin film layer, and an electron transport region thin film layer, wherein the electron transport region thin film layer contains the cyano-modified compound with a dibenzo-p-5-membered ring as a bridging structure.

[0066] Furthermore, the electron transport region thin film layer includes an electron transport layer containing the cyano-modified compound with a dibenzo-5-membered ring as a bridging structure.

[0067] Furthermore, the hole transport region thin film layer includes a hole injection layer, a hole transport layer, and an electron blocking layer; the electron transport region thin film layer includes a hole blocking layer, an electron transport layer, and an electron injection layer; and the electron transport layer contains the cyano-modified compound with a dibenzo-p-5-membered ring as a bridging structure.

[0068] The compounds of this invention employ a dibenzo-5-membered ring as a bridging structure, with two substituted azabenzenes attached to the benzene ring on the same side of the dibenzo-5-membered ring, and a cyano group is introduced as a modifying group. These compounds exhibit good electronic tolerance and stability, as well as excellent electron injection and transport capabilities. Therefore, when used as electron transport materials for OLED functional layers, they can effectively reduce the device driving voltage.

[0069] In particular, when cyano groups are modified on the substituents of azirbenzene, the LUMO electron cloud distribution of the material can be further delocalized, which can improve the material's anti-electron properties and effectively enhance its electronic stability, thereby effectively improving the device's lifespan at room temperature and high temperature.

[0070] Furthermore, under the influence of an electric field or heat, the compounds of this invention, due to their strong electron-withdrawing conjugation effect, readily reduce and ionize lithium ions in lithium complexes, thereby enhancing electron injection capability. Therefore, as electron transport materials, these compounds possess excellent electron transport capabilities and good electron injection properties, effectively reducing device drive voltage, improving device efficiency, and extending device lifespan. Attached Figure Description

[0071] Figure 1 This is a schematic diagram of the structure of an OLED device using the materials listed in this invention. In the figure, 1 is a transparent substrate layer, 2 is an anode layer, 3 is a hole injection layer, 4 is a hole transport layer, 5 is an electron blocking layer, 6 is a light-emitting layer, 7 is a hole blocking layer, 8 is an electron transport layer, 9 is an electron injection layer, 10 is a cathode layer, and 11 is a CPL layer. Detailed Implementation

[0072] The technical solution of the present invention will be described in detail below with reference to the implementation scheme.

[0073] In this invention, unless otherwise stated, HOMO refers to the highest occupied orbital of a molecule, and LUMO refers to the lowest empty orbital of a molecule. Furthermore, in this invention, HOMO and LUMO energy levels are represented by absolute values, and comparisons between energy levels are made by comparing their absolute values. Those skilled in the art know that the larger the absolute value of an energy level, the lower its energy.

[0074] In the accompanying drawings, the dimensions of layers and regions may be exaggerated for clarity. It will also be understood that when a layer or element is referred to as being "above" another layer or substrate, the layer or element may be located directly above that other layer or substrate, or there may be intermediate layers. Furthermore, it will be understood that when a layer is referred to as being "between" two layers, the layer may be the only layer between the two layers, or there may be one or more intermediate layers.

[0075] In this invention, the terms "upper" and "lower," used to indicate orientation when describing electrodes, organic electroluminescent devices, and other structures, only indicate orientation in a specific state and do not imply that the related structures can only exist in the stated orientation. Conversely, if a structure can be repositioned, such as by inverting it, the orientation of the structure changes accordingly. Specifically, in this invention, the "lower" side of an electrode refers to the side of the electrode closer to the substrate during fabrication, while the opposite side farther from the substrate is the "upper" side.

[0076] In this invention, C6 to C 30 Aryl refers to an aryl group having 6 to 30 carbon atoms, preferably an aryl group having 6 to 18 carbon atoms, and even more preferably an aryl group having 6 to 12 carbon atoms. Other preferred aryl groups include phenyl, naphthyl, diphenyl, terphenyl, anthracene, phenanthrene, dimethylfluorenyl, diphenylfluorenyl, spirofluorenyl, condensed tetraphenyl, and pyrene. The compounds include, but are not limited to, triphenyl, peryl, and indole.

[0077] In this invention, C2 to C 30 The heteroaryl group refers to a heteroaryl group having 2 to 30 carbon atoms, preferably a heteroaryl group having 2 to 20 carbon atoms, more preferably a heteroaryl group having 4 to 20 carbon atoms, more preferably a heteroaryl group having 4 to 12 carbon atoms, more preferably a heteroaryl group having 5 to 12 carbon atoms, and preferably furanyl, thiophene, pyrrole, pyrazolyl, imidazolyl, triazolyl, oxazolyl, thiazolyl, oxadiazolyl, thiadiazolyl, pyridinyl, pyrimidinyl, pyrazinyl, or triazine. The following are listed: benzofuranyl, benzothiophenyl, benzoimidazolyl, indolyl, quinolinyl, isoquinolinyl, quinazolinyl, quinolinyl, quinoxolinyl, naphridinyl, benzooxazinyl, benzothiazinyl, benzopyrimidinyl, acridineyl, phenazinyl, phenthiazinyl, phenoxazinyl, furanyl, dibenzofuranyl, dibenzothiophenyl, benzodibenzofuranyl, benzodibenzothiophenyl, carbazolyl, N-phenylcarbazolyl, benzoindolyl, but not limited to these.

[0078] In this invention, C6 to C 30The arylene group refers to an arylene group having 6 to 30 carbon atoms, preferably an arylene group having 6 to 18 carbon atoms, and more preferably an arylene group having 6 to 12 carbon atoms. Other preferred arylene groups include phenylene, naphthylene, diphenylene, terphenylene, anthracene, phenanthrene, dimethylfluorene, diphenylfluorene, spirofluorene, tetraphenylene, pyrene, and others. It can be alkyl, triphenylene, perylene, indene, but is not limited to these.

[0079] In this invention, C2 to C 30 Heteroaryl refers to a heteroaryl group having 2 to 30 carbon atoms, preferably a heteroaryl group having 2 to 20 carbon atoms, preferably a heteroaryl group having 4 to 20 carbon atoms, preferably a heteroaryl group having 4 to 12 carbon atoms, preferably a heteroaryl group having 5 to 12 carbon atoms, preferably a furanyl, thiopheneyl, pyrrolyl, pyrazolyl, imidazolyl, triazolyl, oxazolyl, thiazolyl, oxadiazolyl, thiazolyl, pyridinyl, pyrazinyl, triazinyl, etc. Benzofuranyl, benzothiophenyl, benzoimidazolyl, indoleyl, quinolinyl, isoquinolinyl, quinazolinyl, quinoxolinyl, naphthinyl, benzooxazinyl, benzopyrimidinyl, acridineyl, phenazinyl, phenathiazinyl, phenoxazinyl, phenazinyl, dibenzofuranyl, dibenzothiophenyl, benzodibenzofuranyl, benzodibenzothiophenyl, carbazolyl, N-phenylcarbazolyl, benzoindoleyl, but not limited to these.

[0080] Organic electroluminescent devices

[0081] The organic electroluminescent device of the present invention can be a bottom-emitting organic electroluminescent device, a top-emitting organic electroluminescent device, a single-layer organic electroluminescent device, or a multilayer organic electroluminescent device, and there is no specific limitation thereto.

[0082] The organic electroluminescent device of the present invention includes a substrate, a first electrode, a multilayer organic thin film layer, and a second electrode. The multilayer organic thin film layer includes a hole transport region, a light-emitting layer, and an electron transport region. The hole transport region includes a hole injection layer, a hole transport layer, and an electron blocking layer. The electron transport region includes a hole blocking layer, an electron transport layer, and an electron injection layer. Additionally, a CPL layer (also called a light extraction layer or capping layer) may be disposed on the second electrode.

[0083] The organic electroluminescent device of the present invention may include the following layers and their positional relationships: it may include a substrate, a first electrode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a second electrode. If the above layers are present, the first electrode is on the substrate, the hole injection layer is on the first electrode, the hole transport layer is on the hole injection layer, the electron blocking layer is on the hole transport layer, the light-emitting layer is on the electron blocking layer, the hole blocking layer is on the light-emitting layer, the electron transport layer is on the hole blocking layer, the electron injection layer is on the electron transport layer, the second electrode is on the electron injection layer, and the CPL layer is on the second electrode.

[0084] As the substrate for the organic electroluminescent device of this invention, any substrate commonly used in organic electroluminescent devices can be used. Examples include transparent substrates, such as glass or transparent plastic substrates; opaque substrates, such as silicon substrates; and flexible PI film substrates. Different substrates have different mechanical strengths, thermal stability, transparency, surface smoothness, and water resistance. Their application varies depending on their properties. In this invention, a transparent glass substrate is preferred, and the thickness of the substrate is not particularly limited.

[0085] A first electrode is formed on a substrate, and the first electrode and a second electrode may be opposite each other. The first electrode can be an anode or a cathode. In this invention, the first electrode serves as the anode, and the anode material is preferably a material with a high work function so that holes can be easily injected into the organic functional material layer. Non-limiting examples of anode materials include, but are not limited to, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO2), zinc oxide (ZnO), magnesium (Mg), aluminum (Al), silver (Ag), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), and magnesium-silver (Mg-Ag). The first electrode may have a single-layer structure or a multilayer structure comprising two or more layers. In addition, the thickness of the anode depends on the material used, typically 50-500 nm, preferably 70-300 nm, and more preferably 100-200 nm.

[0086] The hole injection layer, hole transport layer, and electron blocking layer can be disposed between the first electrode and the light-emitting layer.

[0087] The hole injection layer may comprise a host material and a p-type doped material. The host material may be selected from conventional hole transport materials in the prior art, preferably the same organic material as the hole transport layer. The p-type doped material is selected from charge-conducting compounds disclosed in the prior art, and may be selected from compounds disclosed in the following patent documents: WO2011073149A, EP1968131A1, EP2276085A1, EP2213662A1, EP1722602A1, EP2 045848A1, DE102007031220A1, US20100181555A1, US20100102709A1, WO2009003455A1, WO2010094378A1, WO2011120709A1, US20100096600A1, DE102012209523A1, CN101728485A and WO2012095143A1, but not limited to these.

[0088] For example, the compounds shown below:

[0089]

[0090] According to the present invention, P-1 is preferably used as the P-type doped material.

[0091] The thickness of the hole injection layer of the present invention can be 1-100 nm, preferably 2-50 nm, and more preferably 5-20 nm.

[0092] The material of the hole transport layer is preferably a material with high hole mobility, which enables holes to be transferred from the anode or hole injection layer to the light-emitting layer.

[0093] Preferably, the hole transport layer material of the present invention may be selected from the compounds disclosed in the prior art:

[0094]

[0095] The thickness of the hole transport layer of the present invention can be 5-200 nm, preferably 10-180 nm, and more preferably 20-150 nm.

[0096] The electron blocking layer requires that its triplet (T1) energy level be higher than that of the host material in the emissive layer, thus blocking energy loss from the emissive layer material. The HOMO energy level of the electron blocking layer material should be between that of the hole transport layer material and the host material of the emissive layer, facilitating hole injection from the positive electrode into the emissive layer. Simultaneously, the electron blocking layer material should possess high hole mobility to promote hole transport and reduce the power consumption of the device. The LUMO energy level of the electron blocking layer material should be higher than that of the host material of the emissive layer, serving as an electron blocker; that is, the electron blocking layer material should have a wide bandgap (Eg). Electron blocking layer materials meeting these conditions can be triarylamine derivatives, fluorene derivatives, spirofluorene derivatives, dibenzofuran derivatives, carbazole derivatives, etc.

[0097] In one embodiment of the present invention, the electron blocking layer material may be selected from the compounds disclosed in the prior art:

[0098]

[0099] According to the present invention, the thickness of the electron blocking layer can be 1-200 nm, preferably 5-150 nm, and more preferably 5-50 nm.

[0100] According to the present invention, the light-emitting layer is located between the electron blocking layer and the hole blocking layer. The material of the light-emitting layer is a material that emits visible light by respectively receiving holes from the hole transport region and electrons from the electron transport region, and combining the received holes and electrons. The light-emitting layer may include a host material and a dopant material. As the host material and guest material of the light-emitting layer of the organic electroluminescent device of the present invention, the host material may be one or a combination of two of anthracene derivatives, quinoxaline derivatives, triazine derivatives, xanthanone derivatives, diphenyl ketone derivatives, carbazole derivatives, pyridine derivatives, or pyrimidine derivatives. The guest material may be a pyrene derivative, boron derivative, chrysodium derivative, spirofluorene derivative, iridium complex, or platinum complex.

[0101] The thickness of the light-emitting layer of the present invention can be 5-60 nm, preferably 10-50 nm, and more preferably 20-45 nm.

[0102] A hole-blocking layer can be disposed above the emissive layer. The triplet (T1) energy level of the hole-blocking layer material is higher than the T1 energy level of the main emissive layer material, thus preventing energy loss from the emissive layer material. The HOMO energy level of the material is lower than the HOMO energy level of the main emissive layer material, also serving to block holes. Simultaneously, the hole-blocking layer material is required to have high electron mobility to facilitate electron transport and reduce the power consumption of the device. Hole-blocking layer materials meeting these conditions can be triazine derivatives, azirene derivatives, etc. Triazine derivatives are preferred, but not limited to these.

[0103] As the hole blocking layer of the organic electroluminescent device of the present invention, the hole blocking layer materials for organic electroluminescent devices disclosed in the prior art can be used:

[0104]

[0105]

[0106] The thickness of the hole blocking layer of the present invention can be 2-200 nm, preferably 5-150 nm and more preferably 5-50 nm, but the thickness is not limited to this range.

[0107] An electron transport layer can be disposed above the light-emitting layer or the hole-blocking layer. The electron transport layer material is one that readily receives electrons from the cathode and transfers them to the light-emitting layer. The electron transport layer comprises one or more cyano-modified compounds of the present invention with a dibenzo-pentacyclic ring as a bridging structure. Preferably, the electron transport layer consists of the cyano-modified compound of the present invention with a dibenzo-pentacyclic ring as a bridging structure and other commonly used electron transport layer materials in the art. Preferably, the electron transport layer consists of the compound of the present invention and Liq, wherein the ratio of the organic compound of the present invention to other electron transport layer materials is 1:9-9:1, preferably 2:8-8:2, more preferably 4:6-6:4, and most preferably 5:5.

[0108] The thickness of the electron transport layer of the present invention can be 10-80 nm, preferably 20-60 nm, and more preferably 25-45 nm.

[0109] According to the present invention, an electron injection layer may be disposed between the electron transport layer and the cathode. The electron injection layer material is generally preferably a material with a low work function, which facilitates electron injection into the organic functional material layer. Preferably, the electron injection layer material is an N-type metal material. As the electron injection layer material for the organic electroluminescent device of the present invention, the following electron injection layer materials for organic electroluminescent devices disclosed in the prior art can be used: LiF, Cs₂CO₃, CsF, Csq, NaF, MgF₂, CaF₂, Al₂O₃, and Yb.

[0110] The thickness of the electron injection layer of the present invention can be 0.1-5 nm, preferably 0.5-3 nm and more preferably 0.8-1.5 nm, but the thickness is not limited to this range.

[0111] According to the present invention, as described above, the second electrode can be either a cathode or an anode. In this invention, the second electrode is used as the cathode. The material used to form the cathode can be a material with low work function, such as a metal, alloy, conductive compound, or a mixture thereof. Non-limiting examples of cathode materials may include lithium (Li), ytterbium (Yb), magnesium (Mg), aluminum (Al), calcium (Ca), as well as aluminum-lithium (Al-Li), magnesium-indium (Mg-In), and magnesium-silver (Mg-Ag). The thickness of the cathode depends on the material used, typically 5-100 nm, preferably 7-50 nm, and more preferably 10-25 nm.

[0112] Optionally, to improve the light extraction efficiency of the organic electroluminescent device, a CPL layer may be added above the second electrode (i.e., the cathode) of the device. The following compounds disclosed in the art in the prior art can be used as CPL layer materials.

[0113]

[0114]

[0115] The thickness of the CPL layer is typically 5-300 nm, preferably 20-100 nm, and more preferably 40-80 nm.

[0116] Organic electroluminescent devices may also include an encapsulation structure. The encapsulation structure may be a protective structure preventing external substances such as moisture and oxygen from entering the organic layer of the organic electroluminescent device. The encapsulation structure may be, for example, a glass or metal container, or a thin film covering the entire surface of the organic layer.

[0117] Methods for fabricating organic electroluminescent devices

[0118] The present invention provides a method for fabricating the aforementioned organic electroluminescent device, comprising sequentially laminating a first electrode, a multilayer organic thin film layer, and a second electrode on a substrate. The multilayer organic thin film layer is formed by sequentially laminating a hole transport region, a light-emitting layer, and an electron transport region on the first electrode from bottom to top. The hole transport region is formed by sequentially laminating a hole injection layer, a hole transport layer, and an electron blocking layer on the first electrode from bottom to top, and the electron transport region is formed by sequentially laminating a hole blocking layer, an electron transport layer, and an electron injection layer on the light-emitting layer from bottom to top. Optionally, a CPL layer may also be laminated on the second electrode to improve the light extraction efficiency of the organic electroluminescent device.

[0119] Regarding lamination, methods such as vacuum deposition, vacuum evaporation, spin coating, casting, LB method, inkjet printing, laser printing, or LITI can be used, but are not limited to these. Among them, vacuum evaporation refers to heating the material and depositing it onto the substrate in a vacuum environment.

[0120] In this invention, vacuum evaporation is preferably used to form the various layers, wherein the vapor deposition process can be carried out at a temperature of about 100-500°C for about 10... -8 -10 -2 The vacuum degree and about Vacuum evaporation is performed at a rate of [missing information]. The vacuum level is preferably 10 [missing information]. -6 -10 -2 Torr, more preferably 10 -5 -10 -3 Torr. The rate is approximately More preferably, about

[0121] In addition, it should be noted that the materials used to form each layer described in this invention can be used as a single layer by forming a film on their own, or they can be used as a single layer by mixing with other materials to form a film. They can also be a stacked structure between layers that are formed on their own, a stacked structure between layers that are formed by mixing, or a stacked structure between layers that are formed on their own and layers that are formed by mixing.

[0122] Display device

[0123] The present invention also relates to a display device including the aforementioned organic electroluminescent devices, particularly a flat panel display device. In a preferred embodiment, the display device may include one or more of the aforementioned organic electroluminescent devices, and in the case of multiple devices, the devices are stacked laterally or vertically. The display device may also include at least one thin-film transistor. The thin-film transistor may include a gate electrode, a source electrode and a drain electrode, a gate insulating layer and an active layer, wherein one of the source electrode and the drain electrode may be electrically connected to a first electrode of the organic electroluminescent device. The active layer may include crystalline silicon, amorphous silicon, organic semiconductor or oxide semiconductor, but is not limited thereto.

[0124] Exemplary embodiments have been disclosed herein. While specific terminology has been used, it is intended and interpreted in a general and descriptive sense only, and not for limiting purposes. In some instances, as will be apparent to those skilled in the art upon the filing of this application, features, characteristics, and / or elements described in connection with particular embodiments may be used alone or in combination with features, characteristics, and / or elements described in connection with other embodiments, unless specifically indicated otherwise. Accordingly, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope of the invention.

[0125] The following examples are intended to better explain the present invention, but the scope of the invention is not limited thereto.

[0126] Example

[0127] I. Compound Preparation Examples

[0128] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0129] All raw materials involved in the synthesis embodiments of the present invention can be purchased from the market or obtained by conventional preparation methods in the art;

[0130] Synthesis of intermediate B-1:

[0131]

[0132] Preparation of intermediate O-1: Under a nitrogen atmosphere, raw material A-6 (13.17 g, 0.05 mol) was added to a three-necked flask, and a mixed solvent (100 ml toluene, 50 ml ethanol, 50 ml H2O) was added to dissolve it. The mixture was stirred under nitrogen for 1 hour. Then, raw material A-5 (16.63 g, 0.06 mol), K2CO3 (9.95 g, 0.072 mol), and Pd(PPh3)4 (0.462 g, 0.0004 mol) were slowly added. The mixture was heated to 75 °C and reacted for 5 hours. The reaction was observed using thin-layer chromatography (TLC) until complete. After natural cooling, the mixture was filtered, and the filtrate was rotary evaporated and passed through a silica gel column to obtain intermediate O-1. LC-MS: Measured value: 369.16 ([M+H) + Theoretical value: 368.08;

[0133] Preparation of intermediate B-1: Under nitrogen protection, intermediate O-1 (1.11 g, 3 mmol), starting material A-7 (0.84 g, 3.3 mmol), KOAC (0.88 g, 9 mmol), and dioxane (20 ml) were added sequentially to a round-bottom flask. Nitrogen gas was purged for 30 min to replace the air. Pd(PPh3)4 (0.07 g, 0.06 mmol) was then added, and the mixture was heated under reflux for 18 h under nitrogen protection. TLC analysis of the reaction solution showed that intermediate O-1 reacted completely. After the reaction was complete, the reaction system was naturally cooled to room temperature, poured into a separatory funnel, shaken, and allowed to stand for separation. The aqueous phase was extracted with dichloromethane (40 ml * 3). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated to remove dichloromethane, yielding intermediate B-1.

[0134] The synthesis methods of intermediates B-2, B-3, B-6, B-7, and B-8 are similar to those of intermediate B-1, with the same reaction conditions. The difference lies in the starting materials and intermediates used, as shown in Table 1.

[0135] Table 1

[0136]

[0137] Synthesis of intermediate B-4:

[0138]

[0139] Preparation of intermediate O-4: In a three-necked flask under nitrogen protection, starting materials A-13 (3.77 g, 12 mmol), A-12 (2.23 g, 10.0 mmol), Pd(dppf)Cl2 (73 mg, 0.1 mmol), and Na2CO3 (3.34 g, 31.5 mmol) were dissolved in a mixture of THF / water (50 ml / 20 ml). The mixture was heated to 70 °C and stirred overnight. After cooling to room temperature, a saturated ammonium chloride solution (100 ml) was added, and the organic layer was extracted with dichloromethane (4 x 50 ml). The combined organic extracts were dried over magnesium sulfate, filtered, and concentrated under reduced pressure. The residue was purified by rapid chromatography on silica gel (petroleum ether / ethyl acetate 9 / 1) to give intermediate O-4. LC-MS: Measured value: 412.10 ([M+H) + Theoretical value: 411.04;

[0140] Preparation of intermediate B-4: Under nitrogen protection, intermediate O-4 (0.82 g, 2 mmol), raw material A-17 (0.36 g, 2.2 mmol), K2CO3 (0.83 g, 6 mmol), tetrahydrofuran (25 ml), and water (10 ml) were added sequentially to a 100 ml round-bottom flask. Nitrogen gas was purged for 40 min to replace the air. Pd(PPh3)4 (0.05 g, 0.04 mmol) was added, and the mixture was heated under nitrogen protection and refluxed for 15 h. TLC analysis of the reaction solution showed that intermediate O-4 reacted completely. After the reaction was complete, the reaction system was naturally cooled to room temperature, the solvent was removed by rotary evaporation, the residue was dissolved in 100 ml of dichloromethane, washed with 150 ml of water, poured into a separatory funnel, shaken, and allowed to stand for separation. The aqueous phase was extracted with dichloromethane (30 ml × 4). The organic phases were combined, dried with anhydrous magnesium sulfate, filtered, and the filtrate was rotary evaporated to remove dichloromethane to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain intermediate B-4. LC-MS: Measured value: 454.21 ([M+H) + Theoretical value: 453.16;

[0141] Synthesis of intermediate B-5:

[0142]

[0143] Preparation of intermediate B-5: Under a nitrogen atmosphere, raw material A-8 (18.44 g, 0.05 mol) was added to a three-necked flask, dissolved in a mixed solvent (100 ml toluene, 50 ml ethanol, 50 ml H2O). The mixture was stirred under nitrogen for 1 hour. Then, raw material A-15 (9.95 g, 0.06 mol), K2CO3 (9.95 g, 0.072 mol), and Pd(dppf)Cl2 (0.29 g, 0.0004 mol) were slowly added. The mixture was heated to 75 °C and reacted for 8 hours. The reaction was observed using thin-layer chromatography (TLC) until complete. After natural cooling, the mixture was filtered, and the filtrate was rotary evaporated and passed through a silica gel column to obtain intermediate B-5. LC-MS: Measured value: 455.13 ([M+H) + Theoretical value: 454.16;

[0144] Synthesis of intermediate B-9:

[0145]

[0146] Preparation of intermediate B-9: Refer to the preparation of intermediate B-5, except that starting material A-15 was replaced with starting material A-17. LC-MS: Measured value: 455.24 ([M+H]). + Theoretical value: 454.16;

[0147] Example 1: Synthesis of Compound 16:

[0148]

[0149] Preparation of intermediate U-1: Under a nitrogen atmosphere, raw material A-1 (14.08 g, 50 mmol) was added to a three-necked flask and dissolved in a mixed solvent (100 ml toluene, 50 ml ethanol, 50 ml H2O). The mixture was stirred under nitrogen for 1 hour. Then, intermediate B-1 (27.62 g, 60 mmol), K2CO3 (9.95 g, 72 mmol), and Pd(PPh3)4 (0.462 g, 0.4 mmol) were slowly added. The mixture was heated to 75 °C and reacted for 6 hours. The reaction was observed by thin-layer chromatography (TLC) until complete. After natural cooling, the mixture was filtered, and the filtrate was rotary evaporated and passed through a silica gel column to obtain intermediate U-1.

[0150] Preparation of Compound 16: In a three-necked flask under nitrogen protection, starting material A-4 (4.24 g, 12 mmol), intermediate U-1 (5.35 g, 10.0 mmol), Pd(dppf)Cl2 (73 mg, 0.1 mmol), and Na2CO3 (3.34 g, 31.5 mmol) were dissolved in a mixture of THF / water (50 ml / 20 ml). The mixture was heated to 70 °C and stirred overnight. After cooling to room temperature, a saturated solution of ammonium chloride (100 ml) was added, and the organic layer was extracted with dichloromethane (4 x 50 ml). The combined organic extracts were dried over magnesium sulfate, filtered, and concentrated under reduced pressure. The residue was purified by rapid chromatography on silica gel (petroleum ether / ethyl acetate 9 / 1) to give intermediate compound 16.

[0151] The synthetic methods of compounds 117, 158, 235, 244, 430, and 548 are similar to those of compound 16, with the same reaction conditions. The difference lies in the starting materials and intermediates used, as shown in Table 2.

[0152] Table 2

[0153]

[0154]

[0155] Example 2: Synthesis of compound 296:

[0156]

[0157] Preparation of intermediate U-6: Refer to the preparation of intermediate O-1, except that raw material A-6 is replaced by raw material A-2 and raw material A-5 is replaced by intermediate B-4.

[0158] Preparation of compound 296: Refer to the preparation of compound 16, except that raw material A-4 is replaced by raw material A-5 and intermediate U-1 is replaced by intermediate U-6.

[0159] The synthesis methods of compounds 332, 505, and 515 are similar to those of compound 296, with the same reaction conditions. The difference lies in the starting materials and intermediates used, which are shown in Table 3.

[0160] Table 3

[0161]

[0162]

[0163] Example 3: Synthesis of compound 338:

[0164]

[0165] Preparation of intermediate U-8: Refer to the preparation of intermediate O-1, except that raw material A-6 is replaced by raw material A-1.

[0166] Preparation of compound 338: Under a nitrogen atmosphere, intermediate U-8 (21.7 g, 50 mmol) was added to a three-necked flask and dissolved in a mixed solvent (100 ml toluene, 60 ml ethanol, 50 ml H2O). The mixture was stirred under nitrogen for 1 hour. Then, intermediate B-1 (27.62 g, 60 mmol), K2CO3 (9.95 g, 72 mmol), palladium acetate (0.057 g, 0.25 mmol), and Xphos (0.238 g, 0.5 mmol) were slowly added. The mixture was heated to 75 °C and reacted for 6 hours. The reaction was observed by thin-layer chromatography (TLC) until complete. After natural cooling, the mixture was filtered, and the filtrate was rotary evaporated and passed through a silica gel column to obtain compound 338.

[0167] The synthesis methods of compounds 400, 428, 472, and 537 are similar to those of compound 338, with the same reaction conditions. The difference lies in the starting materials and intermediates used, which are shown in Table 4.

[0168] Table 4

[0169]

[0170]

[0171] Example 4: Synthesis of compound 375:

[0172]

[0173] Preparation of intermediate U-9: Refer to the preparation of intermediate U-1, except that raw material A-2 is used instead of raw material A-1, and intermediate B-6 is used instead of intermediate B-1.

[0174] Preparation of compound 375: Refer to the preparation of compound 338, except that intermediate B-1 is replaced by intermediate B-2 and intermediate U-8 is replaced by intermediate U-9.

[0175] The structural characterization of the compounds obtained in each embodiment is shown in Table 5:

[0176] Table 5

[0177]

[0178]

[0179] II. Device Examples

[0180] The following describes in detail the application effects of the compounds synthesized according to the present invention as electron transport materials in devices through device Examples 1-18 and device Comparative Examples 1-12. Compared with Device Comparative Example 1, Device Examples 1-18 and Device Comparative Examples 2-12 have the same fabrication process, use the same substrate and electrode materials, and maintain the same electrode film thickness. The only difference is the change in the electron transport layer material. The device layer structure is shown in Table 6, and the performance test results of each device are shown in Table 7.

[0181] The molecular structural formulas of the relevant materials are shown below:

[0182]

[0183]

[0184] The structures of compounds ET-1, ET-2, ET-3, ET-4, ET-5, ET-6, ET-7, ET-8, ET-9, ET-10, ET-11, and ET-12 are shown above. All of the above materials were commercially available.

[0185] Device Comparison Example 1

[0186] The specific preparation process is as follows:

[0187] like Figure 1 As shown, the transparent substrate layer 1 is transparent glass. Ag (100nm) is deposited as the anode layer 2. On the anode layer 2, HT-1 and P-1 with a thickness of 10nm are deposited using a vacuum evaporation apparatus as the hole injection layer 3, with a mass ratio of HT-1 to P-1 of 97:3. Next, HT-1 with a thickness of 130nm is deposited as the hole transport layer 4. Subsequently, EB-1 with a thickness of 5nm is deposited as the electron blocking layer 5. After the electron blocking materials are deposited, the light-emitting layer 6 of the organic electroluminescent device is fabricated, using BH-1 as the host material and BD-1 as the dopant material, with a doping ratio of 3% by weight, and a light-emitting layer thickness of 20nm. After the light-emitting layer 6, HB-1 is deposited with a thickness of 5nm as the hole blocking layer 7. On the hole blocking layer 7, ET-1 and Liq are deposited with a mass ratio of ET-1 to Liq of 1:1. The vacuum-deposited film of this material is 30 nm thick, and this layer is the electron transport layer 8. On the electron transport layer 8, a 1 nm thick LiF layer is fabricated using a vacuum evaporation apparatus; this layer is the electron injection layer 9. On the electron injection layer 9, a 16 nm thick Mg:Ag electrode layer is fabricated using a vacuum evaporation apparatus, with a Mg to Ag mass ratio of 1:9; this layer is used as the cathode layer 10. On the cathode layer 10, a 65 nm thick CP-1 layer is vacuum-deposited as the CPL layer 11.

[0188] Device Examples 1-18 and Device Comparative Examples 2-12 were prepared in a similar manner to Device Comparative Example 1, except that the electron transport layer materials in Table 6 below were used.

[0189] Table 6

[0190]

[0191]

[0192]

[0193]

[0194]

[0195] The devices fabricated in Part II were tested, including their drive voltage and LT95 lifetime. The voltage was measured using an IVL (current-voltage-luminance) testing system (Suzhou Fushida Scientific Instruments Co., Ltd.), with a current density of 10 mA / cm². 2 LT95 refers to the time it takes for the device's brightness to decay to 95% of its initial brightness, measured at a current density of 20 mA / cm². 2 The lifetime testing system is the EAS-62C OLED device lifetime tester from System Technology Inc., Japan. The high-temperature lifetime test temperature is 85℃. The high-temperature lifetime LT90 refers to the time it takes for the device brightness to decay to 90% of its initial brightness. The current density during the test is 20mA / cm². 2 ;

[0196] The test results are shown in Table 7 below.

[0197] Table 7

[0198]

[0199]

[0200] As can be seen from the device test data in Table 7 above, compared with the comparative devices using ET-1, ET-2, ET-3, ET-4, ET-5, ET-6, ET-7, ET-8, ET-9, ET-10, ET-11 and ET-12 as electron transport layer materials, the device prepared using the compound of the present invention as the electron transport layer material has a significantly lower driving voltage, while at the same time extending the device's room temperature lifetime and improving the device's high temperature lifetime.

[0201] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cyano-modified compound with a dibenzo-5-membered ring as a bridging structure, characterized in that, The structure of the compound is shown in general formula (1): In general formula (1), X represents an oxygen atom or a sulfur atom; X1, X2, X3, X4, X5, and X6 are each independently represented as nitrogen atoms or CH; and at least one of X1-X3 is represented as a nitrogen atom, and at least one of X4-X6 is represented as a nitrogen atom. R1, R2, R3, and R4 represent, independently, Ra-substituted or unsubstituted C6-C atoms. 30 Aryl, Ra-substituted or unsubstituted C2-C 30 Mixed aromatics; L1 and L represent, independently, direct bonds, Rb-substituted bonds, or unsubstituted C6-C bonds, respectively. 30 arylene, Rb-substituted or unsubstituted C2-C 30 heteroaryl; Ra and Rb are independently represented as cyano, deuterium, phenyl, cyano-substituted phenyl, naphthyl, or diphenyl; At least one of R1, R2, R3, R4, L, and L1 is replaced by a cyano group; Any hydrogen atom in the compound shown in general formula (1) can be replaced by a deuterium atom.

2. The cyano-modified compound with a dibenzo-5-membered ring as a bridging structure according to claim 1, characterized in that, The structure of the compound is shown in any one of general formulas (2-1) to (2-6): In general formulas (2-1) to (2-6), the meanings of X, X1, X2, X3, X4, X5, X6, R1, R2, R3, R4, L1, and L are the same as those in general formula (1) of claim 1; Any hydrogen atom in the compounds shown in general formulas (2-1) to (2-6) can be replaced by a deuterium atom.

3. The cyano-modified compound with a dibenzo-five-membered ring as a bridging structure according to claim 1, characterized in that, The structure of the compound is shown in any one of general formulas (3-1) to (3-15): In general formulas (3-1) to (3-15), the meanings of X, R1, R2, R3, R4, L1, and L are the same as those defined in general formula (1) of claim 1; In the compounds shown by general formulas (3-1) to (3-15), any hydrogen atom can be replaced by a deuterium atom.

4. The cyano-modified compound with a dibenzo-5-membered ring as a bridging structure according to claim 1, characterized in that, At least one of R1, R2, R3, and R4 is replaced by a cyano group.

5. The cyano-modified compound with a dibenzo-five-membered ring as a bridging structure according to claim 1, characterized in that, The structure of the compound is shown in any one of general formulas (4-1) to (4-11): In general formulas (4-1) to (4-11), the meanings of X, X1, X2, X3, X4, X5, X6, R1, R2, R3, R4, L1, L, and Rb are the same as those in general formula (1) of claim 1. In the compounds shown by general formulas (4-1) to (4-11), any hydrogen atom can be replaced by a deuterium atom.

6. The cyano-modified compound with a dibenzo-five-membered ring as a bridging structure according to claim 1, characterized in that, R1, R2, R3, and R4 are each independently represented as Ra-substituted or unsubstituted phenyl, Ra-substituted or unsubstituted naphthyl, Ra-substituted or unsubstituted diphenyl, Ra-substituted or unsubstituted terphenyl, Ra-substituted or unsubstituted phenanthyl, Ra-substituted or unsubstituted pyridyl, Ra-substituted or unsubstituted pyrimidinyl, Ra-substituted or unsubstituted dibenzofuranyl, Ra-substituted or unsubstituted dibenzothiophenyl, Ra-substituted or unsubstituted carbazolyl, and Ra-substituted or unsubstituted N-phenylcarbazolyl. Preferably, R1, R2, R3, and R4 are each independently represented as follows: any one of them; L1 and L are respectively independently represented as a direct bond, Rb-substituted or unsubstituted phenylene, Rb-substituted or unsubstituted diphenylene, Rb-substituted or unsubstituted terphenylene, Rb-substituted or unsubstituted tetraphenylene, Rb-substituted or unsubstituted naphthylene, Rb-substituted or unsubstituted phenanthrene, Rb-substituted or unsubstituted pyridylene, Rb-substituted or unsubstituted pyrimidinylene, Rb-substituted or unsubstituted dibenzofuranylene, Rb-substituted or unsubstituted dibenzothiophenylene, Rb-substituted or unsubstituted carbazolylene, and Rb-substituted or unsubstituted N-phenylcarbazolylene. Preferably, L1 and L are each represented independently as follows: any one of them; The meanings of Ra and Rb are the same as those defined in claim 1.

7. The cyano-modified compound with a dibenzo-five-membered ring as a bridging structure according to claim 1, characterized in that, The specific structure of the compound is any one of the following structures:

8. An organic electroluminescent device, comprising a substrate, a first electrode, and a second electrode, wherein a multilayer organic thin film layer is disposed between the first electrode and the second electrode, characterized in that, The organic thin film layer contains the cyano-modified compound with a dibenzo-five-membered ring bridging structure as described in any one of claims 1 to 7; Preferably, the organic thin film layer includes a hole transport region thin film layer, a light emission region thin film layer, and an electron transport region thin film layer, wherein the electron transport region thin film layer contains a cyano-modified compound with a dibenzo-p-5-membered ring bridging structure as described in any one of claims 1 to 7.

9. The organic electroluminescent device according to claim 8, characterized in that, The electron transport region thin film layer includes an electron transport layer containing a cyano-modified compound with a dibenzo-5-membered ring bridging structure as described in any one of claims 1 to 7.

10. The organic electroluminescent device according to claim 8, characterized in that, The hole transport region thin film layer comprises a hole injection layer, a hole transport layer, and an electron blocking layer; the electron transport region thin film layer comprises a hole blocking layer, an electron transport layer, and an electron injection layer; and the electron transport layer contains a cyano-modified compound with a dibenzo-5-membered ring bridging structure as described in any one of claims 1 to 7.

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