A spiro compound, an organic electroluminescent device, and a display device

Abstract

The present disclosure provides a spiro compound, an organic electroluminescent device, and a display device, belonging to the field of display technologies. The general structural formula of the spiro compound of the present disclosure is as shown below: wherein X is one of a direct bond, O, S, C, Si, and N; at least one of X1 to X8 contains N, and the rest are CR3; at least one of X1 to X8 contains an electron-withdrawing group, and R3 cannot be hydrogen at the same time; at least one of ring A and ring B includes a substituted or unsubstituted C10-30 fused polycyclic aromatic ring.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of display, and particularly relates to a spiro compound, an organic electroluminescent device, and a display device. Background Art

[0002] Organic electroluminescent displays (OLEDs) have the advantages of being light, thin, self-luminous, low power consumption, without a backlight source, wide viewing angle, fast response, etc. They have gradually replaced liquid crystal display panels as a new generation of flat panel displays and also have great potential in flexible displays. Currently, OLEDs have been gradually applied to high-end display fields such as mobile phones, wearable devices, vehicles, and computers. Many companies are also developing foldable and rollable OLED screens to meet people's requirements for large-screen experience and product portability. The organic electron transport materials in OLED devices have a significant impact on their performance. The currently disclosed electron transport materials need to be improved in terms of efficiency and lifespan. Therefore, developing stable and efficient electron transport materials, improving device efficiency, and extending device lifespan have important practical application values. Summary of the Invention

[0003] The present disclosure aims to solve at least one of the technical problems existing in the prior art, and provides a spiro compound, an organic electroluminescent device, and a display device.

[0004] In a first aspect, the technical solution adopted to solve the technical problems of the present disclosure is a spiro compound, the structural general formula of which is shown as the following general formula (I):

[0005]

[0006] Wherein, X is one of a direct bond, O, S, C, Si, and N; at least one of X1 to X8 contains N, and the rest are CR3; at least one of X1 to X8 contains an electron-withdrawing group, and R3 cannot be hydrogen at the same time; at least one of ring A and ring B includes a substituted or unsubstituted C10-30 fused polycyclic aromatic ring.

[0007] In some embodiments, ring A and ring B each independently include any one of a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted phenanthrene, a substituted or unsubstituted fluoranthene, a substituted or unsubstituted fluorene, a substituted or unsubstituted thiophene, and a substituted or unsubstituted furyl group.

[0008] In some embodiments, R3 independently represents any one of hydrogen, deuterium, a halogen group, a nitrile group, a nitro group, a hydroxyl group, a carbonyl group, an ester group, an imide group, an amide group, an alkyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group, an alkenyl group, a silyl group, a boron group, an amine group, a phosphine oxide group, an aryl group, a heteroaryl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted pyrimidinyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted pyridazinyl group, a substituted or unsubstituted pyrazinyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted imidazolyl group, a substituted or unsubstituted thiazolyl group, a substituted or unsubstituted oxazolyl group, a substituted or unsubstituted 1,2,4-triazolyl group, a substituted or unsubstituted quinolinyl group, a substituted or unsubstituted isoquinolinyl group, a substituted or unsubstituted quinoxalinyl group, a substituted or unsubstituted quinazolinyl group, a substituted or unsubstituted dibenzothiophenyl group, a substituted or unsubstituted dibenzofuranyl group, a substituted or unsubstituted G1 group, a substituted or unsubstituted G2 group, a substituted or unsubstituted G3 group, a substituted or unsubstituted G4 group, and a substituted or unsubstituted G5 group.

[0009] In some embodiments, the G1 group has the following structure (II):

[0010]

[0011] Wherein, at least one of Y1 to Y8 is N, and the rest are C; the substitution conditions of R1 and R2 are the same as those of R3.

[0012] In some embodiments, the G2 group has the following structure (III):

[0013]

[0014]

[0015] In some embodiments, the G3 group has the following structure (IV):

[0016]

[0017] ​Wherein, W independently represents any one of -O-, -S-, -C(R7)(R8)-, -N(R9)-, -Si(R10)(R11)-; L independently represents any one of a single bond, a substituted or unsubstituted C6-30 aryl group, and a substituted or unsubstituted C6-30 heteroaryl group; i represents the number of W, and i is 0 or 1; a represents the number of R4, 0 < a < 4, and a is an integer; b represents the number of R5, 0 < b < 4, and b is an integer; the substitution conditions of R4 to R11 are the same as those of R3.

[0018] In some embodiments, the G4 group has the following structure (V):

[0019]

[0020] Wherein, Y is S or O; E is C or N; d represents the number of R12, 0 < d < 4, and d is an integer; the substitution conditions of R12 are the same as those of R3.

[0021] In some embodiments, the G5 group has the following structure (VI):

[0022]

[0023] Wherein, the substitution conditions of Ar4 to Ar6 are the same as those of Ar1 to Ar3.

[0024] In a second aspect, an organic electroluminescent device provided by an embodiment of the present disclosure includes: a first electrode, a second electrode, and an organic functional layer located between the first electrode and the second electrode; the organic functional layer at least includes a light-emitting layer located between the first electrode and the second electrode, and an electron transport layer located between the light-emitting layer and the second electrode; the material of the electron transport layer includes the spiro compound as described in any one of the above embodiments.

[0025] In some embodiments, the material of the light-emitting layer includes any one of pyrene derivatives, anthracene derivatives, fluorene derivatives, perylene derivatives, styrylamine derivatives, and metal complexes.

[0026] In some embodiments, the organic functional layer further includes a hole injection layer and a hole transport layer sequentially arranged in the direction from the first electrode to the second electrode between the first electrode and the light-emitting layer; wherein, the material of the hole injection layer includes inorganic oxides, and the material of the hole transport layer includes any one of arylamines, dimethylfluorene, and carbazole materials.

[0027] In a third aspect, a display device provided by an embodiment of the present disclosure includes the organic electroluminescent device as described in any one of the above embodiments. Description of the Drawings

[0028] Figure 1 This is a schematic diagram of the regional division of the general formula (I) in the embodiments of the present disclosure;

[0029] Figure 2 This is a schematic diagram of the film layer structure of an organic electroluminescent device provided by the embodiments of the present disclosure.

[0030] Wherein the reference numerals are: 10, the first electrode; 20, the second electrode; 30, the organic functional layer; HIL, the hole injection layer; HTL, the hole transport layer; EBL, the electron blocking layer; EML, the light emitting layer; HBL, the hole blocking layer; ETL, the electron transport layer; EIL, the electron injection layer. Detailed embodiments

[0031] To make the objectives, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part rather than all of the embodiments of the present disclosure. Usually, the components of the embodiments of the present disclosure described and illustrated herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the claimed present disclosure, but merely represents the selected embodiments of the present disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0032] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should have the ordinary meanings understood by those of ordinary skill in the field to which the present disclosure belongs. The "first", "second" and similar terms used in the present disclosure do not denote any order, quantity or importance, but are only used to distinguish different components. Similarly, the terms such as "a", "an" or "the" do not denote a quantity limitation, but mean that there is at least one. The terms such as "comprising" or "including" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left" and "right" are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0033] As used in this disclosure, "a plurality of" or "several" means two or more. "And / or" describes the relationship between related objects and indicates that there can be three relationships. For example, A and / or B can represent three cases: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally indicates an "or" relationship between the related objects before and after.

[0034] Under the action of an electric field in an OLED device, holes generated by the anode and electrons generated by the cathode will move, be injected into the hole transport layer and the electron transport layer respectively, and migrate to the light-emitting layer. When the two meet in the light-emitting layer, energy excitons are generated. When the excitons drop from the excited state to the ground state, light is emitted, ultimately generating visible light. Therefore, it is necessary to balance the injection and flow of holes and electrons so that the OLED device with the above structure has excellent efficiency.

[0035] The materials used for OLED devices include light-emitting materials, auxiliary materials, and electrode materials. Among them, the auxiliary materials mainly include charge carrier transport materials, charge carrier injection materials, and charge carrier blocking materials. Charge carrier transport materials are hole transport materials and electron transport materials. Different auxiliary materials play different functions and roles in the device, so different physical property requirements are usually imposed on different auxiliary materials. During the process of charge carriers transporting through different functional layers and reaching the light-emitting layer, the energy level barriers between different materials play an extremely important role in the operating voltage of the device. Reducing the energy level / injection barrier between different functional layers and preventing the accumulation of charges due to the energy level barrier of charge carriers contribute to the effective improvement of voltage and lifespan. Therefore, appropriate Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energy levels are important indicators to measure in the development and design of electron transport materials.

[0036] An OLED device is a double-carrier injection device, and the recombination efficiency of charge carriers affects the efficiency of the device. To achieve effective recombination of charge carriers in the light-emitting layer and prevent excitons from diffusing to the surrounding functional layers, it is required that the functional layer adjacent to the light-emitting layer has a relatively high triplet energy level T1. Therefore, the electron transport material should have an appropriate triplet energy level T1 to effectively improve the efficiency of the device.

[0037] Among the materials used for OLED devices, most organic electroluminescent materials have a faster hole transport speed than electron transport speed, which easily causes an imbalance in the number of electrons and holes in the light-emitting layer, resulting in a relatively low efficiency of the device. Therefore, it is very important to develop electron transport materials with high electron mobility.

[0038] When an OLED device operates under an applied voltage, Joule heat is generated, which makes the organic materials prone to crystallization, thus affecting the device's lifespan and efficiency. Therefore, it is necessary to develop stable and efficient organic electroluminescent materials.

[0039] Electron transport materials exhibit an electron-deficient system in their molecular structure and have strong electron groups, which endows them with a certain polarity. Compared with hole transport materials, electron transport materials are more likely to crystallize. This can lead to poor film-forming ability of the materials during the film-forming process due to crystallization, and even cause pore blockage in the materials, which is not conducive to the mass production output of OLED devices. Therefore, during the development and design of electron transport materials, the crystallization performance of the materials is also an important measurement index.

[0040] In summary, excellent electron transport materials should possess the following characteristics:

[0041] 1) Appropriate HOMO and LUMO energy levels. The HOMO-LUMO energy levels are collectively called the frontier orbitals. A lower HOMO energy level can more effectively confine hole carriers in the light-emitting layer, thereby improving the recombination efficiency of holes and electrons; a lower LUMO energy level is conducive to the injection of electrons from the cathode, thus reducing the turn-on voltage of the OLED device.

[0042] 2) A higher triplet energy level T1. Since the lifetime of triplet excitons is relatively long and the diffusion distance is relatively large, electron transport materials with a higher triplet energy level T1 can confine triplet excitons in the light-emitting layer, that is, block the diffusion of triplet excitons from the light-emitting layer to the electron transport layer, thereby increasing the carrier recombination efficiency, improving the utilization rate of excitons, and further enhancing the light-emitting efficiency and service life of the OLED device.

[0043] 3) A higher electron mobility. Mobility affects the driving voltage of the device. A low electron mobility will increase the driving voltage of the device, thereby reducing the power efficiency of the device. In addition, too high a driving voltage of the device will also have a significant impact on the stability of the device. Usually, the mobility of hole transport materials is higher than that of electron transport materials, which leads to an imbalance in the charge transport of holes and electrons and cannot fully recombine to form excitons. While a high electron mobility will be conducive to balancing electrons and holes in the light-emitting layer, simultaneously reducing the driving voltage of the OLED device, thereby reducing the power loss of the OLED device and suppressing polaron-exciton annihilation, and further improving the stability and light-emitting efficiency of the OLED device.

[0044] 4) Can form a good amorphous thin film to avoid performance degradation caused by crystallization.

[0045] The currently disclosed electron transport materials need to be improved in terms of both efficiency and lifespan. Therefore, developing stable and efficient electron transport materials, improving device efficiency, and extending device lifespan have important practical application values.

[0046] In view of this, the embodiments of the present disclosure provide a spiro compound, an organic electroluminescent device, and a display device, which substantially eliminate one or more of the problems caused by the limitations and defects of the related art.

[0047] In a first aspect, the technical solution adopted to solve the technical problems of the present disclosure is a spiro compound, and its structural general formula is shown as the following general formula (I):

[0048]

[0049] Wherein, X is one of a direct bond, O, S, C, Si, and N; at least one of X1 to X8 contains N, and the rest are CR3; at least one of X1 to X8 contains an electron-withdrawing group, and R3 cannot be hydrogen at the same time; at least one of ring A and ring B includes a substituted or unsubstituted C10-30 fused polycyclic aromatic ring.

[0050] It should be noted that at least one of ring A and ring B includes a substituted or unsubstituted C10-30 fused polycyclic aromatic ring, which means that at least one of ring A and ring B includes a substituted C10-30 fused polycyclic aromatic ring or an unsubstituted C10-30 fused polycyclic aromatic ring; wherein, polycyclic means at least two rings. In addition, X in the embodiments of the present disclosure represents one of a direct bond, O, S, C, Si, and N, and X1 to X8 each independently include a substituted or unsubstituted group. When X represents a direct bond, it means that it is not substituted by a group, that is, a five-membered ring structure.

[0051] In some embodiments, ring A and ring B each independently include any one of a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted phenanthrene, a substituted or unsubstituted fluoranthene, a substituted or unsubstituted fluorene, a substituted or unsubstituted thiophene, and a substituted or unsubstituted furyl group.

[0052] In the embodiments of the present disclosure, the compound having the general formula (I) may include the following compounds 1 to 26:

[0053] The structural formula of compound 1 is:

[0054]

[0055] The structural formula of compound 2 is:

[0056]

[0057] The structural formula of Compound 3 is:

[0058]

[0059] The structural formula of Compound 4 is:

[0060]

[0061] The structural formula of Compound 5 is:

[0062]

[0063] The structural formula of Compound 6 is:

[0064]

[0065] The structural formula of Compound 7 is:

[0066]

[0067] The structural formula of Compound 8 is:

[0068]

[0069] The structural formula of Compound 9 is:

[0070]

[0071] The structural formula of Compound 10 is:

[0072]

[0073] The structural formula of Compound 11 is:

[0074]

[0075] The structural formula of Compound 12 is:

[0076]

[0077] The structural formula of Compound 13 is:

[0078]

[0079] The structural formula of Compound 14 is:

[0080]

[0081] The structural formula of Compound 15 is:

[0082]

[0083] The structural formula of Compound 16 is:

[0084]

[0085] The structural formula of Compound 17 is:

[0086]

[0087] The structural formula of Compound 18 is:

[0088]

[0089] The structural formula of Compound 19 is:

[0090]

[0091] The structural formula of Compound 20 is:

[0092]

[0093] The structural formula of Compound 21 is:

[0094]

[0095] The structural formula of Compound 22 is:

[0096]

[0097] The structural formula of Compound 23 is:

[0098]

[0099] The structural formula of Compound 24 is:

[0100]

[0101] The structural formula of Compound 25 is:

[0102]

[0103] The structural formula of Compound 26 is:

[0104]

[0105] Among them, G can be O or S.

[0106] It should be noted that the structure of the compound of general formula (I) is not limited to the above structures.

[0107] For ease of description and understanding, the general formula (I) is divided into regions. Figure 1 This is a schematic diagram of the regional division of the general formula (I) in the embodiments of the present disclosure, as Figure 1As shown, the spiro structure of the general formula (I) is divided into an AA region including X, ring A and ring B, and a BB region including X1 to X8.

[0108] In the embodiments of the present disclosure, the compound with the general formula (I) has a spiro structure as the backbone, and has the advantages of many reactive sites, and the molecular structure and energy band can be modified; the spiro structure has a typical large-volume π-system structure of non-planar cross-crossing, so that its orbital energy levels are completely separated, which is beneficial to effective electronic structure regulation and realizes the performance of multifunctional devices under different modifications of a model compound; the SP3 hybridization of the central C atom of the compound with the general formula (I) in the embodiments of the present disclosure breaks the conjugation of the molecule, which can prevent the reduction of the triplet energy level T1, and at the same time makes the HOMO and LUMO energy levels distributed in the upper and lower parts of the AA region and the BB region of the general formula (I), which is beneficial to the regulation of the energy levels of the electron transport material containing the compound in the embodiments of the present disclosure; the compound with the general formula (I) in the embodiments of the present disclosure has a spiro structure as the backbone and has a very strong rigid structure. Further, an asymmetric spiro structure can be adopted, thereby effectively reducing the symmetry of the molecule and increasing the glass transition temperature Tg of the electron transport material containing the compound in the embodiments of the present disclosure, which is beneficial to improving the film-forming property of the molecule.

[0109] It should be noted that the compound with the general formula (I) in the embodiments of the present disclosure is doped with N atoms on the basis of the spiro structure, which makes the physical properties of the electron transport material containing the compound in the embodiments of the present disclosure easier to regulate, so as to match with the adjacent functional layer and meet the requirements of the device performance of different structures.

[0110] Continue to refer to Figure 1 , in the AA region of the compound with the general formula (I) in the embodiments of the present disclosure, at least one of ring A and ring B includes a substituted or unsubstituted C10-30 fused polycyclic aromatic ring. Such a setting has a greater electron cloud density relative to the unfused fragment and is more conducive to the flow of charges. In this way, no matter what type of electron-withdrawing group the BB region linked to the SP3 hybridized central C atom of the compound with the general formula (I) in the embodiments of the present disclosure is linked to, the HOMO is always distributed in the AA region and the LUMO is always distributed in the BB region.

[0111] Further, the compound with the general formula (I) in the embodiments of the present disclosure has a nitrogen-containing spiro structure as the backbone and has a certain electron-withdrawing ability itself. When the BB region is linked to an electron-withdrawing group, the selection range of the type of electron-withdrawing group is larger, which can make up for the defects of groups with weaker electron-withdrawing ability. For example, groups with weaker electron-withdrawing ability can be appropriately selected.

[0112] Further, in the AA region of the compound having the general formula (I) in the embodiments of the present disclosure, heteroatoms (for example, O, S, N) may be contained. Such a setting makes the electron transport material containing the compound in the embodiments of the present disclosure have a relatively large polarity and better interfacial energy levels with adjacent functional layers, thereby further strengthening the interaction with adjacent functional layers.

[0113] In the embodiments of the present disclosure, the compound having the general formula (I) has a nitrogen heterospiro ring as a backbone, is fused in the AA region, and is directly or indirectly (for example, through an aromatic group) connected to an electron-withdrawing group (for example, the electron-withdrawing group can be azine-based, phenanthroline-based, benzoxazole-based, benzophenone-based, etc.) in the BB region. Since both the nitrogen heterospiro ring and the electron-withdrawing group are strong electron-withdrawing groups, the electron transport material containing the compound in the embodiments of the present disclosure can have a deep LUMO energy level and a high electron mobility. In addition, through the modification of aromatic groups and different types of electron-withdrawing groups, the LUMO energy level of the compound having the general formula (I) in the embodiments of the present disclosure can be flexibly adjusted, so that the electron transport material containing the compound in the embodiments of the present disclosure has an appropriate LUMO energy level, effectively reducing the injection barrier between the electron transport material containing the compound in the embodiments of the present disclosure and the cathode and adjacent functional layers, thereby improving the electron injection ability of the electron transport material containing the compound in the embodiments of the present disclosure; the electron transport material containing the compound in the embodiments of the present disclosure has a more matched LUMO energy level with adjacent functional layers, making the prepared OLED device have an extremely low driving voltage. At the same time, fusing in the AA region can well regulate the HOMO level, making the electron transport material containing the compound in the embodiments of the present disclosure have the ability to block holes, thereby increasing the recombination probability of excitons in the light-emitting layer.

[0114] In some embodiments, R3 independently represents any one of hydrogen, deuterium, a halogen group, a nitrile group, a nitro group, a hydroxyl group, a carbonyl group, an ester group, an imide group, an amide group, an alkyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group, an alkenyl group, a silyl group, a boron group, an amine group, a phosphinyl group, an aryl group, a heteroaryl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted pyrimidinyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted pyridazinyl group, a substituted or unsubstituted pyrazinyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted imidazolyl group, a substituted or unsubstituted thiazolyl group, a substituted or unsubstituted oxazolyl group, a substituted or unsubstituted 1,2,4-triazolyl group, a substituted or unsubstituted quinolinyl group, a substituted or unsubstituted isoquinolinyl group, a substituted or unsubstituted quinoxalinyl group, a substituted or unsubstituted quinazolinyl group, a substituted or unsubstituted dibenzothiophenyl group, a substituted or unsubstituted dibenzofuranyl group, a substituted or unsubstituted G1 group, a substituted or unsubstituted G2 group, a substituted or unsubstituted G3 group, a substituted or unsubstituted G4 group, a substituted or unsubstituted G5 group.

[0115] Specifically, in the compound having the general formula (I) in the embodiments of the present disclosure, when X1 to X8 are all N, no additional group needs to be connected. When X1 to X8 are not all N, for example, referring to the structural formula of Compound 18 above, if X1 is N, then the remaining X2 to X8 are all represented as CR3. It should be noted that at least one of X1 to X8 contains an electron-withdrawing group, and R3 cannot be hydrogen simultaneously.

[0116] In some embodiments, the G1 group has the following structure (II):

[0117]

[0118] Wherein, at least one of Y1 to Y8 is N, and the rest are C; the substitution situations of R1 and R2 are the same as those of R3.

[0119] Specifically, the substitution patterns of R1 and R2 being the same as those of R3 mean that R1 and R2 each independently represent hydrogen, deuterium, a halogen group, a nitrile group, a nitro group, a hydroxyl group, a carbonyl group, an ester group, an imide group, an amide group, an alkyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group, an alkenyl group, a silyl group, a boron group, an amine group, a phosphine oxide group, an aryl group, a heteroaryl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted pyrimidinyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted pyridazinyl group, a substituted or unsubstituted pyrazinyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted imidazolyl group, a substituted or unsubstituted thiazolyl group, a substituted or unsubstituted oxazolyl group, a substituted or unsubstituted 1,2,4-triazolyl group, a substituted or unsubstituted quinolinyl group, a substituted or unsubstituted isoquinolinyl group, a substituted or unsubstituted quinoxalinyl group, a substituted or unsubstituted quinazolinyl group, a substituted or unsubstituted dibenzothiophenyl group, a substituted or unsubstituted dibenzofuranyl group, a substituted or unsubstituted G1 group, a substituted or unsubstituted G2 group, a substituted or unsubstituted G3 group, a substituted or unsubstituted G4 group, a substituted or unsubstituted G5 group, any one of them.

[0120] In some embodiments, the G2 group has the following structure (Ⅲ):

[0121]

[0122] Wherein, at least one of N1 to N3 contains N, and the rest are C; Ar1 to Ar3 each independently represent any one of a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group.

[0123] In some embodiments, the G3 group has the following structure (Ⅳ):

[0124]

[0125]

[0126] Wherein, W independently represents any one of -O-, -S-, -C(R7)(R8)-, -N(R9)-, -Si(R10)(R11)-; L independently represents any one of a single bond, a substituted or unsubstituted C6-30 aryl group, a substituted or unsubstituted C6-30 heteroaryl group; i represents the number of W, and i is 0 or 1; a represents the number of R4, 0 < a < 4, and a is an integer; b represents the number of R5, 0 < b < 4, and b is an integer; the substitution patterns of R4 to R11 are the same as those of R3.Specifically, when i is 0, W represents a direct bond and is not substituted by a group, that is, it has a five-membered ring structure. The substitution conditions of R4 to R11 being the same as those of R3 mean that R4 to R11 each independently represent hydrogen, deuterium, a halogen group, a nitrile group, a nitro group, a hydroxyl group, a carbonyl group, an ester group, an imide group, an amide group, an alkyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group, an alkenyl group, a silyl group, a boron group, an amino group, a phosphinyl group, an aryl group, a heteroaryl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted pyrimidinyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted pyridazinyl group, a substituted or unsubstituted pyrazinyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted imidazolyl group, a substituted or unsubstituted thiazolyl group, a substituted or unsubstituted oxazolyl group, a substituted or unsubstituted 1,2,4-triazolyl group, a substituted or unsubstituted quinolinyl group, a substituted or unsubstituted isoquinolinyl group, a substituted or unsubstituted quinoxalinyl group, a substituted or unsubstituted quinazolinyl group, a substituted or unsubstituted dibenzothiophenyl group, a substituted or unsubstituted dibenzofuranyl group, a substituted or unsubstituted G1 group, a substituted or unsubstituted G2 group, a substituted or unsubstituted G3 group, a substituted or unsubstituted G4 group, a substituted or unsubstituted G5 group, any one of them.

[0127] In some embodiments, the G4 group has the following structure (V):

[0128]

[0129] Wherein, Y is S or O; E is C or N; d represents the number of R12, 0 < d < 4, and d is an integer; the substitution conditions of R12 are the same as those of R3.

[0130] Specifically, the substitution pattern of R12 being the same as that of R3 means that R12 independently represents any one of hydrogen, deuterium, a halogen group, a nitrile group, a nitro group, a hydroxyl group, a carbonyl group, an ester group, an imide group, an amide group, an alkyl group, a cycloalkyl group, an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an alkylsulfonyl group, an arylsulfonyl group, an alkenyl group, a silyl group, a boron group, an amine group, a phosphine oxide group, an aryl group, a heteroaryl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted pyrimidinyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted pyridazinyl group, a substituted or unsubstituted pyrazinyl group, a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted imidazolyl group, a substituted or unsubstituted thiazolyl group, a substituted or unsubstituted oxazolyl group, a substituted or unsubstituted 1,2,4-triazolyl group, a substituted or unsubstituted quinolinyl group, a substituted or unsubstituted isoquinolinyl group, a substituted or unsubstituted quinoxalinyl group, a substituted or unsubstituted quinazolinyl group, a substituted or unsubstituted dibenzothiophenyl group, a substituted or unsubstituted dibenzofuranyl group, a substituted or unsubstituted G1 group, a substituted or unsubstituted G2 group, a substituted or unsubstituted G3 group, a substituted or unsubstituted G4 group, and a substituted or unsubstituted G5 group.

[0131] In some embodiments, the G5 group has the following structure (VI):

[0132]

[0133] Among them, the substitution pattern of Ar4 to Ar6 is the same as that of Ar1 to Ar3.

[0134] Specifically, the substitution pattern of Ar4 to Ar6 being the same as that of Ar1 to Ar3 means that each of Ar4 to Ar6 independently represents any one of a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group.

[0135] In the embodiments of the present disclosure, a partial structural formula of the compound having the general formula (I) is as follows:

[0136]

[0137]

[0138]

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146]

[0147]

[0148]

[0149]

[0150]

[0151]

[0152]

[0153]

[0154]

[0155]

[0156]

[0157]

[0158]

[0159]

[0160]

[0161]

[0162]

[0163]

[0164]

[0165]

[0166]

[0167]

[0168]

[0169]

[0170] It should be noted that the structural formula of the compound with the general formula (I) is not limited to the above form.

[0171] Specifically, in the compound with the general formula (I) in the embodiments of the present disclosure, since at least one of X1 to X8 contains N, a compound with a nitrogen heterospiro ring as the backbone can be formed. At least one of X1 to X8 contains an electron-withdrawing group, and R3 cannot be hydrogen at the same time, which means that the compound with a nitrogen heterospiro ring as the backbone in the embodiments of the present disclosure is directly or indirectly (for example, through an aromatic group) connected to the electron-withdrawing group. Since both the nitrogen heterospiro ring and the electron-withdrawing group are strong electron-withdrawing groups, the electron transport material containing the compound in the embodiments of the present disclosure can have appropriate HOMO and LUMO energy levels, as well as a high electron mobility.

[0172] Specifically, by modifying with an aromatic group and a group with different electron-withdrawing abilities, the LUMO energy level of the compound in the embodiments of the present disclosure can be adjusted to obtain an appropriate LUMO energy level that meets the requirements, thereby effectively reducing the injection barrier between the cathode and the adjacent functional layer in the electron transport material containing the compound in the embodiments of the present disclosure, improving the electron injection ability of the electron transport material, making it have a more matching LUMO energy level with the adjacent functional layer, and finally obtaining an OLED device with an extremely low driving voltage. At the same time, by modifying with an aromatic group and a group with different electron-withdrawing abilities, the HOMO energy level of the compound in the embodiments of the present disclosure can be adjusted to obtain an appropriate HOMO energy level that meets the requirements, so that the electron transport material containing the compound in the embodiments of the present disclosure has the ability to block holes, thereby increasing the recombination probability of excitons in the light-emitting layer.

[0173] Specifically, the compound in the embodiments of the present disclosure has a nitrogen heterospiro ring as the backbone. By using the SP3 hybridization of the central C atom, a large spatial configuration can be obtained, which can weaken the intermolecular interaction, reduce the intermolecular π-π stacking, and effectively avoid the phenomenon of crucible hole blockage caused by the aggregation of molecules during the evaporation process of the electron transport material containing the compound in the embodiments of the present disclosure.

[0174] Specifically, the compounds in the embodiments of the present disclosure have an azaspiro ring as the backbone and a rigid three-dimensional structure. Such a rigid structure is conducive to increasing the glass transition temperature Tg of the electron transport material containing the compounds in the embodiments of the present disclosure. The level of Tg determines the thermal stability of the electron transport material during evaporation coating. The higher the Tg, the better the thermal stability of the electron transport material, making it less likely to undergo cracking and change during the evaporation coating process. At the same time, the compounds in the embodiments of the present disclosure adopt an asymmetric spiro ring structure, which can reduce the molecular symmetry and is conducive to improving the film-forming property of the molecule. Through the above settings, the electron transport material containing the compounds in the embodiments of the present disclosure has better physical and thermal stability, as well as good durability and heat resistance, thereby being able to improve the light-emitting efficiency and service life of the OLED device.

[0175] In summary, after the electron transport material containing the compounds in the embodiments of the present disclosure is applied to the OLED device, the current efficiency, power efficiency, and external quantum efficiency of the OLED device can all be greatly improved; at the same time, the light-emitting efficiency and service life of the OLED device are improved. The electron transport material containing the compounds in the embodiments of the present disclosure has good application effects and industrialization prospects in the OLED device.

[0176] Next, taking the synthesis example of compound E1 as an example, the preparation method of the compounds of the electron transport material of the present disclosure will be described in detail. However, it can be understood that the preparation method of the compounds of the electron transport material of the present disclosure includes but is not limited to this synthesis example.

[0177] Among them, the structural formula of compound E1 is as follows:

[0178]

[0179] The preparation method of compound E1 specifically includes the following steps:

[0180] (1) Synthesize intermediate 1, specifically as follows:

[0181]

[0182] Under a nitrogen atmosphere, dissolve 75 millimoles (mmol) of compound 1a in 200 mL of tetrahydrofuran (THF) in a three-necked flask, and cool the temperature to -78 °C; slowly add 68 mmol of butyllithium (n-BuLi) dropwise, with the temperature not exceeding -75 °C. After adding butyllithium dropwise, raise the temperature to room temperature and react for 1 h; add a 200 mL THF solution containing 64 mmol of compound 1b to the reaction flask, and reflux the mixture for 3 h; after detecting the reaction is complete by thin layer chromatography (TLC), extract with ethyl acetate; after extraction, concentrate to obtain compound 1c.

[0183] 50 mmol of the above-mentioned compound 1c was added to 200 mL of acetic acid, stirred at 80 °C, and 1-2 drops of sulfuric acid were added dropwise; after refluxing for 3 h, the temperature was lowered to room temperature. After the reaction ended, compound 1d was obtained through extraction and separation (yield 86.42%).

[0184] After completely dissolving 38 mmol of the above-mentioned compound 1d and 40.5 mmol of compound 1e in 170 mL of dioxane, 112.35 mmol of potassium acetate was added and the mixture was heated and stirred. Then the temperature was lowered to room temperature. After the reaction ended, the potassium carbonate solution was removed, and potassium acetate was removed by filtration; the filtrate was solidified with ethanol and filtered; the white solid was washed twice with ethanol to obtain intermediate 1 with a yield of 88.35%.

[0185] In some embodiments, for the preparation of the following intermediate compounds and their yields, refer to Tables 1 to 3, specifically as follows:

[0186] Table 1

[0187]

[0188] Table 2

[0189]

[0190] Table 3

[0191]

[0192] (2) Synthesis of compound E1, specifically as follows:

[0193]

[0194] Under a nitrogen atmosphere, in a 500 ml round-bottom flask, 18 mmol of intermediate 1 and 15.23 mmol of compound 1-A were completely dissolved in 300 ml of tetrahydrofuran, and then 100 ml of 2 M aqueous potassium carbonate solution was added; after adding 0.42 mmol of tetrakis(triphenylphosphine)palladium (Pd(PPh3)4), the mixture was heated and stirred for 4 hours; the temperature was lowered to room temperature, the aqueous layer was removed, dried with anhydrous magnesium sulfate, and then concentrated under reduced pressure; recrystallization was carried out with 250 ml of ethyl acetate to obtain compound E1 with a yield of 79.23%.

[0195] It should be noted that in the preparation methods of different types of compounds of the electron transport materials in the present disclosure, 1a, 1b and the reaction conditions can be adjusted according to actual needs. It can be understood that when different intermediate 1 is prepared, the corresponding 1c is naturally different.

[0196] In some embodiments, the preparation of the following compounds and their yields can be seen in Tables 4 to 5, specifically as follows:

[0197] Table 4

[0198]

[0199] Table 5

[0200]

[0201] Referring to Table 6, the distribution of the electron clouds of some compounds in the embodiments of the present disclosure was simulated using molecular simulation software, specifically as follows:

[0202] Table 6

[0203]

[0204] As can be seen from Table 6 above, in the embodiments of the present disclosure, the compound with the general formula (I) has a spiro ring structure as the backbone, and the sp3 hybridization of the central C atom breaks the conjugation of the molecule, so that the HOMO and LUMO energy levels are distributed in the upper and lower parts of the AA region and the BB region of the general formula (I), which is beneficial to the regulation of the energy levels of the electron transport material containing the compound in the embodiments of the present disclosure, so that the electron transport material containing the compound in the embodiments of the present disclosure has a more matching LUMO energy level with the adjacent functional layer; at the same time, the sp3 hybridization of the central C atom of the compound with the general formula (I) in the embodiments of the present disclosure breaks the conjugation of the molecule, which can prevent the decrease of the triplet energy level T1. The electron transport material containing the compound in the embodiments of the present disclosure can effectively confine the excitons in the light-emitting layer, greatly improve the utilization efficiency of the excitons, and thus significantly improve the light-emitting efficiency of the device.

[0205] For some compounds in the embodiments of the present disclosure, performance parameters were measured: the HOMO / LUMO energy levels were tested using AC3&UV spectroscopy; the mobility was tested using TOF, and the reorganization energy was obtained through simulation calculation. The results can be seen in Table 7, specifically as follows:

[0206] Table 7

[0207]

[0208] As can be seen from Table 7 above, compared with the comparative compounds, in the structure of the compound with the general formula (I) of the present disclosure, by connecting the nitrogen heterocycle with an electron-withdrawing group and changing the nitrogen hetero position of the nitrogen heterocycle in different compounds, the energy levels of the electron transport material can be flexibly adjusted, so that the electron transport material containing the compound in the embodiments of the present disclosure has appropriate HOMO and LUMO energy levels, as well as a relatively high electron mobility, ultimately realizing better electron transport and reducing the operating voltage of the device.

[0209] Furthermore, in the partial structure of the compound with the general formula (I) in the embodiments of the present disclosure, the azacycle is connected to phenanthroline and benzoxazole. Since the nitrogen atom in the azacycle belongs to an SP2 heterocycle, the lone pair electrons on the nitrogen atom do not participate in the π electron heterocycle and can have a strong interaction with adjacent groups. To a certain extent, the dihedral angle with adjacent groups can be reduced, making the molecule have a relatively stable geometric configuration. When the molecule is under the action of an external electric field, the molecule is not easily deformed, its reorganization energy is lower, and the electron mobility is higher (the smaller the dihedral angle, the higher the planarity); at the same time, there is an SP3 hybridized C in the azaspirocycle, making this type of group have a large spatial three-dimensional structure. Introducing a group with a large three-dimensional configuration into the molecule can adjust the intermolecular force of the organic compound in the present disclosure, reduce the intermolecular stacking effect and the molecular crystallization ability, and reduce the crystallization phenomenon caused by Joule heat in the device, thereby improving the device life.

[0210] Using a DSC differential scanning calorimeter as the measuring instrument, the test atmosphere is nitrogen, the heating rate is 10 °C / min, and the temperature range is 50 - 380 °C to test the glass transition temperature (Tg) of some compounds in the embodiments of the present disclosure; at the same time, use a low-temperature phosphorescence spectrometer (T1 = 1240 / PL peak) to measure the triplet energy level T1 of some compounds in the embodiments of the present disclosure. The results can be seen in Table 8 as follows:

[0211] Table 8

[0212] ETL Tg (°C) Tl Compound E2 153 2.51 Compound E3 147 2.56 Compound E4 143 2.55 Compound E10 148 2.59 Compound E13 135 2.48 Compound E14 136 2.52 Compound E15 136 2.5 Compound E16 138 2.47 Comparative ETL 122 2.2

[0213] As can be seen from Table 8 above, since the compound with the general formula (I) in the embodiments of the present disclosure has a rigid three-dimensional structure, such a rigid structure is beneficial to improving the Tg of the material. A high Tg is beneficial to improving the thermodynamic stability of the material, making the material not easily cracked and changed during the evaporation process, and having good moldability, which is a basic condition for the material to be evaporated and maintain a high life. At the same time, introducing an azo electron-withdrawing group into the azacycle structure (for example, the electron-withdrawing group can be selected from azine, phenanthroline, benzoxazole, benzophenone, etc.), these electron-withdrawing groups can form a strong interaction with the azaspirocycle, making the molecule even less likely to deform, further enhancing the rigidity of the molecule, making it have better physical and thermal stability, and having good durability and heat resistance, thereby significantly improving the life of the OLED device.

[0214] Furthermore, when the electron-withdrawing group is a benzoxazole group, since this type of group has a relatively high T1, the T1 of the electron transport material of the compound in the embodiments of the present disclosure containing this type of group is significantly improved. In addition, in the compounds of the embodiments of the present disclosure, the azaspiro ring and the electron-withdrawing group are connected in different ways such as ortho-position and meta-position, which can effectively disrupt and reduce the intermolecular conjugation degree, thereby further improving the T1 of the material. And the electron transport material with high T1 can further improve the utilization rate of excitons, effectively confine the excitons in the light-emitting layer, and ultimately improve the utilization rate of excitons.

[0215] In a second aspect, the embodiments of the present disclosure also provide an organic electroluminescent device. Figure 2 It is a schematic diagram of the film layer structure of an organic electroluminescent device provided by the embodiments of the present disclosure. As Figure 2 shown, it includes: a first electrode 10, a second electrode 20, and an organic functional layer 30 located between the first electrode 10 and the second electrode 20; the organic functional layer 30 at least includes a light-emitting layer EML located between the first electrode 10 and the second electrode 20, and an electron transport layer ETL located between the light-emitting layer EML and the second electrode 20; the material of the electron transport layer ETL includes the spiro compound of any one of the above embodiments.

[0216] Specifically, the organic electroluminescent device in the embodiments of the present disclosure includes a first electrode 10, an organic functional layer 30, and a second electrode 20 stacked in sequence; wherein, the organic functional layer 30 includes a light-emitting layer EML and an electron transport layer ETL, and the material of the electron transport layer ETL includes the spiro compound of any one of the above embodiments. The first electrode 10 is an anode, which can be a transparent conductive polymer. For example, it can be ITO; the second electrode 20 is a cathode.

[0217] In the organic electroluminescent device of the embodiments of the present disclosure, the compound of the electron transport layer ETL material has a spiro structure as the backbone, with the advantages of many reactive sites, and the molecular structure and energy band can be modified, which is beneficial to adjusting molecular properties such as the three-dimensional spatial structure of the molecule, HOMO-LUMO energy levels, and triplet energy level T1, thereby improving the light-emitting efficiency and service life of the OLED device.

[0218] Specifically, the spiro structure has a structure of a typical large-volume π-system with non-planar cross-crossing, which enables the complete separation of its orbital energy levels, facilitating effective electronic structure regulation and realizing multifunctional device performance under different modifications of a model compound; in the embodiments of the present disclosure, the sp3 hybridization of the central C atom of the compound with the general formula (I) interrupts the conjugation of the molecule, which can prevent the reduction of the triplet energy level T1, and at the same time makes the HOMO and LUMO energy levels distributed in the upper and lower parts of the AA region and the BB region of the general formula (I), facilitating the regulation of the energy levels of the electron transport material containing the compound in the embodiments of the present disclosure; the compound with the general formula (I) in the embodiments of the present disclosure has a spiro structure as the backbone and has a strong rigid structure. Further, an asymmetric spiro structure can be adopted, thereby effectively reducing the symmetry of the molecule, enhancing the glass transition temperature Tg of the electron transport material containing the compound in the embodiments of the present disclosure, facilitating the film-forming property of the molecule and the thermal stability of the electron transport material during evaporation, and further enhancing the light-emitting efficiency and service life of the OLED device.

[0219] Specifically, electron-withdrawing groups are introduced into the structure of the compound of the electron transport layer ETL material on the azaspiro ring, such as phenanthroline and benzoxazole groups. These electron-withdrawing groups are connected to the azaspiro ring directly or indirectly and form a strong interaction, making the molecule less likely to deform, further enhancing the rigidity of the molecule, having better physical and thermal stability, and having good durability and heat resistance, thereby significantly improving the service life of the OLED device.

[0220] Further, in the embodiments of the present disclosure, the organic functional layer 30 further includes an electron injection layer EIL disposed on the side of the electron transport layer ETL close to the second electrode 20, a hole blocking layer HBL disposed on the side of the electron transport layer ETL away from the electron injection layer EIL, and a hole injection layer HIL, a hole transport layer HTL, and an electron blocking layer EBL that are sequentially stacked on the side of the first electrode 10 close to the hole blocking layer HBL.

[0221] In the embodiments of the present disclosure, the hole injection layer HIL can be an inorganic oxide, such as molybdenum oxide, titanium oxide, vanadium oxide, rhenium oxide, ruthenium oxide, chromium oxide, zirconium oxide, hafnium oxide, tantalum oxide, silver oxide, tungsten oxide, manganese oxide, or can also be a dopant of a strong electron-withdrawing system, such as hexacyanohexaazatriphenylene, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HATCN), 1,2,3-tris[(cyano)(4-cyano-2,3,5,6-tetrafluorophenyl)methylene]cyclopropane, etc., or P-type doping can also be performed on the hole transport material. The thickness of the hole injection layer HIL can be 5 nm to 30 nm. The material of the hole transport layer HTL is an aromatic amine, dimethylfluorene or carbazole material with good hole transport characteristics, such as 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB), N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]-4,4'-diamine (TPD), 4-phenyl-4'-(9-phenylfluoren-9-yl)triphenylamine (BAFLP), 4,4'-bis[N-(9,9-dimethylfluoren-2-yl)-N-phenylamino]biphenyl (DFLDPBi), 4,4'-di(9-carbazolyl)biphenyl (CBP), 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (PCzPA), etc. The thickness of the hole transport layer HTL can be 100 nm to 2000 nm. The electron blocking layer EBL, that is, the light-emitting auxiliary layer, its material is an aromatic amine or carbazole material with good hole transport characteristics, such as CBP, PCzPA, etc. The thickness of the electron blocking layer EBL can be 5 nm to 100 nm.

[0222] The host material of the light-emitting layer EML can include one material or a mixture of two or more materials. Among them, the blue light-emitting material can be selected from pyrene derivatives, anthracene derivatives, fluorene derivatives, perylene derivatives, styrylamine derivatives, metal complexes, etc. For example, N1,N6-bis([1,1'-biphenyl]-2-yl)-N1,N6-bis([1,1'-biphenyl]-4-yl)pyrene-1,6-diamine, 9,10-di-(2-naphthyl)anthracene (ADN), 2-methyl-9,10-di-2-naphthylanthracene (MADN), 2,5,8,11-tetra-tert-butylperylene (TBPe), 4,4'-bis[4-(diphenylamino)styryl]biphenyl (BDAV Bi), 4,4'-bis[4-(di-p-tolylamino)styryl]biphenyl (DPAVBi), iridium bis(4,6-difluorophenylpyridine-C2,N)picolinate (FIrpic). The thickness of the light-emitting layer EML can be 20 nm to 100 nm.

[0223] The hole blocking layer HBL and the electron transport layer ETL are generally aromatic heterocyclic compounds, such as imidazole derivatives including benzimidazole derivatives, imidazopyridine derivatives, benzimidazophenanthridine derivatives, etc.; pyrazine derivatives including pyrimidine derivatives, triazine derivatives, etc.; compounds containing a nitrogen-containing six-membered ring structure such as quinoline derivatives, isoquinoline derivatives, phenanthroline derivatives (also including compounds having a phosphine oxide-based substituent on the heterocycle), etc. 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (OXD-7), 3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole (TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (p-EtTAZ), bathophenanthroline (BPhen), (BCP), 4,4'-bis(5-methylbenzoxazol-2-yl)stilbene (BzOs), etc. Among them, the electron transport layer ETL can also include the electron transport material of the present application. The thickness of the hole blocking layer HBL can be 5 nm to 100 nm, and the thickness of the electron transport layer ETL can be 20 nm to 100 nm. The electron injection layer EIL is generally an alkali metal or a metal, such as LiF, Yb, Mg, Ca or their compounds, etc. The thickness of the electron injection layer EIL can be 1 nm to 10 nm.

[0224] Among the film layer materials mentioned above in the embodiments of the present disclosure, the structural formulas of some compounds are as follows:

[0225]

[0226] Taking Figure 2 the organic electroluminescent device as an example, the preparation process thereof will be specifically described:

[0227] (1) Ultrasonically treat the glass plate with ITO in a cleaning agent, rinse it in deionized water, ultrasonically remove oil in an acetone-ethanol mixed solvent, and bake it in a clean environment until all moisture is completely removed.

[0228] (2) Place the glass substrate with the anode in a vacuum chamber, evacuate to 1×10 -5 ~1×10 -6 , and vacuum deposit m-MTDATA and F4TCNQ on the above anode layer film in a ratio of 97:3 to form a hole injection layer HIL.

[0229] (3) Evaporate m-MTDATA on the hole injection layer HIL to form a hole transport layer HTL.

[0230] (4) Evaporate the light-emitting material by vacuum evaporation on the side of the electron blocking layer (EBL) away from the hole transport layer (HTL) to form the light-emitting layer (EML). The light-emitting layer (EML) includes a host material and a guest material. The co-evaporation method with multiple sources can be used. The weight ratio of the host material to the guest material is 90:10. The host material is CBP, and the guest material is Ir(pyy)3.

[0231] (5) Evaporate the hole blocking material by vacuum evaporation on the side of the light-emitting layer (EML) away from the electron blocking layer (EBL) to form the hole blocking layer (HBL). Evaporate TPBi by vacuum evaporation on the side of the light-emitting layer (EML) away from the electron blocking layer (EBL) to form the hole blocking layer (HBL) of the device.

[0232] (6) Evaporate the electron transport material by vacuum evaporation on the side of the hole blocking layer (HBL) away from the light-emitting layer (EML) to form the electron transport layer (ETL). It should be noted that when forming the electron transport layer (ETL), the electron transport layer (ETL) material in the present disclosure can be used. In the prior art, BCP and Liq are often co-evaporated with a mass ratio of 1:1 on the side of the hole blocking layer (HBL) away from the light-emitting layer (EML) to form the electron transport layer (ETL) of the device.

[0233] (7) Evaporate Yb with a thickness of 1 nm as the electron injection material by vacuum evaporation on the side of the electron transport layer (ETL) away from the hole blocking layer (HBL) to form the electron injection layer (EIL).

[0234] (8) Co-evaporate Mg and Al with a mass ratio of 8:2 by double-source co-evaporation on the side of the electron injection layer (EIL) away from the electron transport layer (ETL) to form the cathode of the device.

[0235] (9) Evaporate the CPL material on the cathode with a thickness of 60 nm. (Not shown in the figure)

[0236] Among them, the thickness of each film layer of the organic electroluminescent device can be: the hole injection layer (HIL) is 10 nm, the hole transport layer (HTL) is 100 nm; the electron blocking layer (EBL) is 35 nm; the light-emitting layer (EML) is 20 nm; the hole blocking layer (HBL) is 5 nm; the electron transport layer (ETL) is 30 nm; the electron injection layer (EIL) is 1 nm.

[0237] In some embodiments, the thickness range of the cathode is 100-170 nm. The cathode includes a Yb layer and an Mg / Ag layer. The thickness of the Yb layer is about 3-15 nm. The ratio of Mg to Ag in the Mg / Ag layer can be 0.5-9.5 to 2.5-7.5. Appropriately increasing the thickness of Yb can increase the injection of electrons inside the light-emitting device, which is beneficial to reducing the operating voltage of the device. Further, the content of Ag in the cathode can be increased. The resistivity of Ag is much lower than that of Mg. Increasing the proportion of Ag can effectively reduce the voltage drop, thereby further reducing the power consumption of the product.

[0238] Next, the device performance of the organic light-emitting device using some of the compounds in the embodiments of the present disclosure as the electron transport layer (ETL) material is measured under a fixed current density. Among them, the tested performance includes driving voltage, luminous efficiency, and service life. The compound used in the comparative example is the above-mentioned comparative ETL. The electron transport material in the light-emitting device of Example 1 includes Compound E2; the electron transport layer (ETL) material in the light-emitting device of Example 2 includes Compound E3; the electron transport material in the light-emitting device of Example 3 includes Compound E4; the electron transport material in the light-emitting device of Example 4 includes Compound E10; the electron transport material in the light-emitting device of Example 5 includes Compound E13; the electron transport material in the light-emitting device of Example 6 includes Compound E14; the electron transport material in the light-emitting device of Example 7 includes Compound E15; the electron transport material in the light-emitting device of Example 8 includes Compound E16. The test results can be seen in Table 9, as follows:

[0239] Table 9

[0240] Example ETL Voltage Emission peak (nm) CIEx CIEv Efficiency Lifetime (LT95) Example 1 Compound E2 95.83％ 459 0.140 0.132 103.35％ 104.43％ Example 2 Compound E3 94.01％ 461 0.140 0.132 106.55％ 102.73％ Example 3 Compound E4 96.59％ 457 0.141 0.132 104.76％ 104.96％ Example 4 Compound E10 93.34％ 459 0.141 0.132 101.23％ 101.78％ Example 5 Compound E13 97.34％ 458 0.142 0.132 100.54％ 102.29％ Example 6 Compound E14 96.77％ 460 0.141 0.132 103.97％ 104.43％ Example 7 Compound E15 94.56％ 461 0.141 0.132 105.23％ 104.62％ Example 8 Compound E16 94.01％ 460 0.142 0.132 106.09％ 108.96％ Comparative Example Comparative ETL 100％ 461 0.140 0.132 100％ 100％

[0241] It can be seen from Table 9 that the driving voltages of Examples 1 to 8 are all lower than that of the comparative example. This is because the ETL contains the compounds in the embodiments of the present disclosure, which have strong electron-withdrawing groups and structures with relatively high triplet energy levels T1, thereby improving the electron injection performance of the electron transport material, making the carrier transport smoother while reducing the driving voltage of the OLED device, and further improving the display performance of the OLED device. At the same time, the improvement in luminous efficiency and service life of Examples 1 to 8 is also relatively significant compared to the comparative example. In short, the electron transport material in the embodiments of the present disclosure has a relatively high glass transition temperature Tg, which is beneficial to improving the stability of the electron transport material and further improving the luminous efficiency and service life of the light-emitting device.

[0242] In a third aspect, the embodiments of the present disclosure also provide a display device, which includes the organic light-emitting device according to any one of the above embodiments. The display devices of the embodiments of the present disclosure include, but are not limited to, devices such as mobile phones, tablet computers, personal digital assistants, smart watches, in-vehicle displays, digital cameras, laptop computers, head-up displays, wearable devices, virtual reality, and augmented reality, so as to achieve the design effect of the unity of the full screen and interaction or other effects.

[0243] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principles of the present disclosure, and the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present disclosure, and these modifications and improvements are also regarded as the protection scope of the present disclosure.

Claims

1. A spiro compound, characterized in that, The structural general formula is as follows: Wherein, X is O; both X1 and X8 are N; X2-X7 are CR3; the R3 in X2-X6 independently represents any one of hydrogen, a halogen group, a nitrile group, a nitro group, and a hydroxyl group; R3 in X7 has the following structure:

2. A spiro compound, characterized in that, Any one of the following structures:

3. An organic electroluminescent device, characterized in that, Comprising: A first electrode, a second electrode, and an organic functional layer located between the first electrode and the second electrode; the organic functional layer at least includes a light-emitting layer located between the first electrode and the second electrode, and an electron transport layer located between the light-emitting layer and the second electrode; the material of the electron transport layer includes the spiro compound as described in claim 1 or 2.

4. A display device, characterized in that, Comprising the organic electroluminescent device as described in claim 3.

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