Deuterated compounds, their preparation methods, applications, and organic electroluminescent devices

Abstract

This application discloses a deuterated compound, its preparation method, uses, and organic electroluminescent devices, relating to the field of organic electroluminescent materials. The deuterated compound has the structural formula shown in Formula I: Formula I; In Formula I, L1 and L2 are each independently selected from single bonds, substituted or unsubstituted C6-C12 aryl groups, and substituted or unsubstituted C3-C12 heteroaryl groups; at least one of Ar1 and Ar2 is 9,9-dimethylfluorenyl, and the remainder are selected from substituted or unsubstituted C6-C18 aryl groups and substituted or unsubstituted C6-C18 heteroaryl groups; L1, L2, Ar1, and Ar2 are each independently unsubstituted or substituted; if substituted, the substituent is selected from C1-C5 alkyl groups and C6-C12 aryl groups. The deuterated compound of this application can effectively improve device lifespan while maintaining cost-effectiveness.

Description

Technical Field

[0001] This application relates to the field of organic electroluminescent materials technology, specifically to a deuterated compound, its preparation method, uses, and organic electroluminescent devices. Background Technology

[0002] Organic light-emitting devices (OLEDs) have many advantages, such as low driving voltage, high luminous brightness and luminous efficiency, wide viewing angle, fast response speed, and relatively simple fabrication process, which have attracted widespread attention from academia and industry.

[0003] Despite significant progress in the research of organic electroluminescent devices, the demands on their performance continue to rise as the market expands and deepens, with device lifetime being a particularly prominent issue. Therefore, effectively improving device lifetime has become a long-standing and in-depth research topic for both academia and industry. Currently, the industry commonly improves device lifetime by increasing the degree of deuteration in materials, but this method often comes with high synthesis costs. Therefore, in the industry's conventional approach, using deuteration strategies to improve device lifetime usually requires sacrificing some cost, which poses a significant economic challenge for the large-scale application of deuterated compounds. Summary of the Invention

[0004] The technical problem addressed by this application is how to effectively improve the lifespan of organic electroluminescent devices while maintaining low cost.

[0005] To solve the above-mentioned technical problems, this application provides the following technical solution:

[0006] In a first aspect, this application provides a deuterated compound having the structural formula shown in Formula I: Formula I; in Formula I, L1 and L2 are each independently selected from single bonds, substituted or unsubstituted C6-C12 arylene groups, substituted or unsubstituted C3-C12 heteroarylene groups; at least one of Ar1 and Ar2 is 9,9-dimethylfluorenyl, and the rest are selected from substituted or unsubstituted C6-C18 aryl groups, substituted or unsubstituted C6-C18 heteroaryl groups; L1, L2, Ar1 and Ar2 are each independently unsubstituted or substituted; if substituted, the substituent is selected from C1-C5 alkyl groups or C6-C12 aryl groups.

[0007] In a second aspect, this application provides a method for preparing a deuterated compound, comprising: reacting 1,3-dihalobenzene-d4 with benzaldehyde to obtain a first compound; the structural formula of the first compound is as follows: X1 is selected from chlorine, bromine, and iodine; the first compound is reacted with a halobiphenyl to give a second compound; the structural formula of the second compound is... The second compound undergoes an intramolecular dehydration reaction to yield a third compound; the structural formula of the third compound is as follows: The third and fourth compounds are subjected to a Buchwald-Hartwig coupling reaction to yield the deuterated compound as described in the first aspect; the fourth compound has the following structural formula: The definitions of L1, L2, Ar1 and Ar2 are the same as those described in the first aspect.

[0008] In a third aspect, this application provides the use of the deuterated compound according to the first aspect or the deuterated compound prepared according to the preparation method of the second aspect in the preparation of organic electroluminescent devices.

[0009] In a fourth aspect, this application provides an organic electroluminescent device, including a first electrode, a second electrode, and an organic layer located between the first electrode and the second electrode, wherein the organic layer comprises a deuterated compound prepared according to the first aspect or a deuterated compound prepared according to the preparation method of the second aspect.

[0010] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0011] The deuterated compound of this application is based on a 9,9-diphenylfluorenyl skeleton, with an arylamine group replacing the 3-position of either of the two phenyl groups at the 9-position of the fluorenyl group, and the remaining four hydrogen atoms on the phenyl group being replaced with deuterium atoms. This design effectively improves device lifetime and meets practical application requirements by deuterating only a few specific positions, thus breaking the traditional understanding that "the lifetime improvement of organic electroluminescent devices is positively correlated with the degree of deuteration of the material." Simultaneously, this deuterated compound significantly reduces deuteration costs, achieving a balance between lifetime improvement and cost control, overcoming the predicament in existing technologies where "improving lifetime through deuteration strategies requires sacrificing cost," and possessing outstanding industrialization value.

[0012] Furthermore, the preparation method of the deuterated compound in this application uses existing deuterated compounds with the target deuteration site required in this application as starting materials for synthesis, without the need for additional deuteration steps. This not only ensures a high deuteration rate at the target deuteration site, but also further reduces the amount of deuteration reagent used, significantly reducing the generation of deuteration waste. It has significant advantages such as simple synthesis process, environmental protection, and low cost, and has good potential for large-scale production and application. Attached Figure Description

[0013] The following accompanying drawings describe in detail the exemplary embodiments disclosed in this application. The same reference numerals denote similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting and exemplary, and the drawings are for illustrative purposes only and are not intended to limit the scope of this application. Other embodiments may similarly fulfill the inventive intent of this application. It should be understood that the drawings are not drawn to scale. Wherein:

[0014] Figure 1 This is a schematic diagram of the structure of the organic electroluminescent devices prepared in Examples 9 and 13 of this application. Detailed Implementation

[0015] The following description provides specific application scenarios and requirements for this application, intended to enable those skilled in the art to make and use the content of this application. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this application.

[0016] Deuterium (D) is a stable, non-radioactive isotope found in nature. Due to its greater atomic mass than hydrogen, its CD bond has a shorter bond length and higher bond energy, making it approximately 6-9 times more stable than a CH bond. Introducing deuterium atoms into OLED materials can stabilize the molecular structure, significantly improving the luminous efficiency and stability of OLED devices and extending their lifespan. Furthermore, industry experience suggests that a higher degree of deuteration is more beneficial for extending device lifespan (due to the cumulative enhancement effect of deuteration), ideally achieving full deuteration for optimal device lifespan.

[0017] Research has shown that the gradual deuteration of the host material has a cumulative enhancement effect on device lifetime. Highly deuterated host materials can increase lifetime by more than four times, and this deuteration strategy is universally applicable to all OLED materials in extending device lifetime (Cumulative Lifetime Enhancement Effect of Deuteration in BlueOLEDs. International Conference on Display Technology 2023 (Volume 54, Issue S1)). Related studies have also disclosed the relationship between the degree of deuteration and device lifetime. By increasing the number of deuterium atoms in an organic electron donor material (PNA) from 5 to 22, the lifetime of LT90 devices increased from 8.2 hours to 33.6 hours, a fourfold increase. Therefore, the increase in lifetime is directly proportional to the degree of deuteration of the host molecule (LifetimeEnhancement and Degradation Study of Blue OLEDs Using Deuterated Materials. ACS Appl. Mater. Interfaces 2023, 15, 7255-7262). However, a higher degree of deuteration means a greater amount of deuterating reagent is required, and multiple deuterations are usually needed to increase the degree of deuteration. This results in a long synthesis cycle, high cost, and the generation of a large amount of deuteration waste, which is not environmentally friendly. If a deuteration strategy is used to improve device lifespan, it usually means sacrificing some cost, which has become the industry's common practice.

[0018] However, the inventors of this application unexpectedly discovered that in the 9,9-diphenylfluorene structure, when the 3-position of any one of the two phenyl groups at the 9-position of the fluorene group (hereinafter referred to as "9-position phenyl") is replaced by an arylamine group, it is only necessary to replace the remaining 4 hydrogen atoms on the "9-position phenyl" with deuterium atoms (hereinafter referred to as "9-position phenyl tetradeuterated") to effectively improve the device lifespan of the entire compound (hereinafter referred to as "9-position phenyl tetradeuterated compound").

[0019] Compared to compounds where the entire "9-position phenyl" and "arylamine" groups are fully deuterated (i.e., fully deuterated in the highest occupied molecular orbital (HOMO) region) (hereinafter referred to as "HOMO fully deuterated compounds"), the device lifetime of 9-position phenyl tetradeuterated compounds does not decrease proportionally with the decrease in the number of deuterium atoms. This differs from the view disclosed in the prior art that "the increase in lifetime is proportional to the degree of deuteration of the main molecule." If the improvement in device lifetime of HOMO fully deuterated compounds relative to undeuterated compounds is taken as 100%, then the contribution of "9-position phenyl tetradeuterated" to the lifetime improvement can reach more than 30%. The reason for this may be that the lone pair electrons of the nitrogen atom in the "arylamine" group increase the electron cloud density of the "9-position phenyl," thereby enhancing its chemical reactivity. Therefore, replacing the remaining four hydrogen atoms on the "9-position phenyl" with deuterium atoms can effectively increase the bond energy, enhance the overall stability of the molecule, and thus benefit the improvement of device lifetime.

[0020] Meanwhile, compared with HOMO fully deuterated compounds, the preparation cost of 9-position phenyl tetradeuterated compounds decreases significantly with the reduction of deuteration sites. Thus, the trade-off between improved device lifetime and reduced preparation cost is effectively mitigated.

[0021] Based on this, this application provides a deuterated compound with the structural formula shown in Formula I: Formula I.

[0022] In Formula I, L1 and L2 are each independently selected from single-bonded, substituted or unsubstituted C6-C12 arylene, or substituted or unsubstituted C3-C12 heteroarylene. At least one of Ar1 and Ar2 is 9,9-dimethylfluorenyl, and the remainder are selected from substituted or unsubstituted C6-C18 aryl, or substituted or unsubstituted C6-C18 heteroaryl. L1, L2, Ar1, and Ar2 are each independently unsubstituted or substituted; if substituted, the substituent is selected from C1-C5 alkyl or C6-C12 aryl.

[0023] Unless otherwise specified, "a certain group of Cn~Cm" in the text refers to a certain group with n to m carbon atoms. For example, "an arylene of C6~C12" refers to an arylene with 6 to 12 carbon atoms.

[0024] Unless otherwise specified, "aryl" in this document can refer to monocyclic or polycyclic aryl groups; monocyclic aryl groups include, but are not limited to, phenyl and tolyl; polycyclic aryl groups include fused-ring aryl groups, biphenyl-type aryl groups, and polyphenylalanine groups, wherein fused-ring aryl groups include, but are not limited to, naphthyl, anthraceneyl, phenanthryl, and fluorenyl, and biphenyl-type aryl groups include biphenyl; polyphenylalanine groups are structures formed by multiple aromatic rings linked by alkyl groups, such as diphenylmethyl ( In this paper, * represents a connection site in the structural formula.

[0025] Unless otherwise specified, "arylene" in this article refers to a divalent group formed by removing two hydrogen atoms from an aromatic hydrocarbon molecule, or it can be considered as a divalent group formed by removing one hydrogen atom from an aryl group. Except for being a divalent group, its definition is subject to the above-mentioned explanations of aryl groups. For example, arylene groups include phenylene, tolyl, biphenylene, naphthylene, anthracene, phenanthrene, fluorene, etc. wait.

[0026] Unless otherwise specified, "heteroaryl" in this document refers to an aryl group containing at least one of B, N, O, P, S, Si, and Se, including but not limited to pyridyl, pyrroloyl, pyrimidinyl, pyridazinyl, furanyl, thiopheneyl, imidazolyl, pyrazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, triazolyl, diazolyl, thiadiazolyl, tetrazolyl, pyrazinyl, thiazolyl, triazinyl, tetraazinyl, quinolinyl, isoquinolinyl, indolyl, indoleyl, indoleyl, phthalazinyl, pyridopyrimidinyl, pyridopyrazinyl, pyrazinopyrazinyl, benzothiazolyl, benzooxazolyl, benzoimidazolyl, benzothiopheneyl, benzofuranyl, dibenzofuranyl, dibenzothiopheneyl, imidazopyridyl, phenanthrolinel, imidazophenanthridyl, naphridinyl, quinazolinyl, quinoxolinyl, etc.

[0027] Unless otherwise specified, "heteroaryl" in this article refers to a divalent group formed by removing two hydrogen atoms from a heteroaryl molecule, or a divalent group formed by removing one hydrogen atom from a heteroaryl group. Except for being a divalent group, its definition can be applied to the aforementioned descriptions of heteroaryl groups, such as pyridinyl, pyrroloyl, pyrimidinyl, pyridazinyl, furanyl, thiopheneyl, imidazolyl, pyrazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, triazolyl, diazolyl, thiazolyl, tetrazolyl, etc. Azolyl, pyrazinyl, thiazinyl, triazinyl, tetrazinyl, quinolinyl, isoquinolinyl, indoleyl, indeneyl, phthalazinyl, pyridinylpyrimidinyl, pyridinylpyrazinyl, pyrazinylpyrazinyl, benzothiazolyl, benzoxazolyl, benzoimidazolyl, benzothiopheneyl, benzofuranyl, dibenzofuranyl, dibenzothiopheneyl, imidazopyridinyl, phenanthrene-pyridinyl, imidazophenanthrene-pyridinyl, naphthinyl, quinoxalinyl, etc.

[0028] Unless otherwise specified, "alkyl" in this article may be a straight-chain or branched structure, such as methyl, ethyl, propyl (n-propyl, isopropyl), butyl (n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl), and pentyl (n-pentyl, isopentyl, neopentyl, tert-pentyl).

[0029] In some preferred embodiments, L1 and L2 are each independently selected from single-bonded, substituted or unsubstituted phenylene, substituted or unsubstituted biphenylene; L1 and L2 are each independently unsubstituted or substituted; if substituted, the substituent is preferably methyl, ethyl, tert-butyl, phenyl, or biphenyl. More preferably, L1 and L2 are independently selected from single-bonded, phenylene, or biphenylene. In some specific embodiments, L1 is selected from single-bonded, phenylene, or biphenylene; L2 is a single bond.

[0030] In some preferred embodiments, at least one of Ar1 and Ar2 is 9,9-dimethylfluorenyl, and the remainder is selected from substituted or unsubstituted phenyl, substituted or unsubstituted biphenyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted dibenzothiopheneyl; Ar1 ​​and Ar2 are each independently unsubstituted or substituted; if substituted, the substituent is preferably methyl, ethyl, tert-butyl, phenyl, or biphenyl. More preferably, at least one of Ar1 and Ar2 is 9,9-dimethylfluorenyl, and the remainder is selected from phenyl, biphenyl, terphenyl, dibenzofuranyl, or dibenzothiopheneyl.

[0031] In some embodiments, the deuterated compound is selected from the group consisting of:

[0032] ;

[0033] Wherein, L1 is selected from single bond, phenylene, and biphenylene; Ar1 ​​is selected from phenyl, biphenyl, terphenyl, dibenzofuranyl, dibenzothiophene, and 9,9-dimethylfluorenyl.

[0034] In some embodiments, the deuterated compound is selected from the group consisting of:

[0035] .

[0036] In some more specific embodiments, the deuterated compound is selected from the group consisting of:

[0037] .

[0038] This application also provides a method for preparing a deuterated compound. This method uses an existing deuterated compound with the target deuteration site required by this application as a starting material for synthesis, without the need for an additional deuteration step. This approach not only achieves a high deuteration rate at the target deuteration site but also further reduces the amount of deuteration reagent used, significantly reducing the generation of deuteration waste, thereby giving the production process more significant environmental and cost advantages.

[0039] The method for preparing the deuterated compound according to the embodiments of this application includes the following steps:

[0040] S1: Reaction of 1,3-dihalobenzene-d4 with benzaldehyde yields the first compound; the structural formula of the first compound is: X1 is selected from chlorine, bromine, and iodine;

[0041] S2: React the first compound with a halobiphenyl to obtain a second compound; the structural formula of the second compound is as follows: ;

[0042] S3: Initiate an intramolecular dehydration reaction of the second compound to obtain a third compound; the structural formula of the third compound is as follows: ;

[0043] S4: The third and fourth compounds undergo a Buchwald-Hartwig coupling reaction to obtain the deuterated compound described above; the structural formula of the fourth compound is: The definitions of L1, L2, Ar1, and Ar2 are the same as those mentioned above.

[0044] In some preferred embodiments, in step S1, the structural formula of the 1,3-dihalophenyl-d4 is as follows: X is selected from chlorine, bromine, and iodine, and the reactivity of X is not lower than that of X1. As an example, neither X nor X1 is bromine; or X is bromine and X1 is chlorine; or X is iodine and X1 is bromine.

[0045] In some preferred embodiments, in step S1, the reaction temperature is 0°C to 50°C and the reaction time is 20 hours to 30 hours.

[0046] In some preferred embodiments, in step S2, the structural formula of the halobiphenyl is: X2 is selected from chlorine, bromine, and iodine.

[0047] In some preferred embodiments, in step S2, the reaction temperature is -40°C to 30°C, and the reaction time is 2 hours to 5 hours.

[0048] In some preferred embodiments, in step S3, the reaction temperature is 100°C to 120°C and the reaction time is 2 hours to 8 hours.

[0049] In some preferred embodiments, in step S4, when the Buchwald-Hartwig coupling reaction is carried out, the catalyst is selected from palladium compounds, the auxiliary ligand is selected from phosphine ligands, and the reaction system is alkaline.

[0050] In some preferred embodiments, in step S4, when the Buchwald-Hartwig coupling reaction is carried out, the solvent used is selected from at least one of benzene, toluene, xylene, and chlorobenzene.

[0051] In some preferred embodiments, in step S4, the reaction temperature is the reflux temperature, and the reaction time is 5 to 10 hours.

[0052] When the 9-position phenyl tetradeuterated compound of this application is used to prepare organic electroluminescent devices, the device lifetime is significantly improved due to the enhanced overall molecular stability. Furthermore, the reduction in deuteration sites drastically reduces the compound's preparation cost. Moreover, in preparing the 9-position phenyl tetradeuterated compound of this application, existing deuterated compounds with the desired deuteration sites can be directly used as starting materials for synthesis, eliminating the need for additional deuteration steps. This not only ensures a high deuteration rate at the target deuteration site but also reduces the amount of deuterating reagent used, further lowering preparation costs. Therefore, when the deuterated compound of this application or the deuterated compound prepared by the method of this application is applied to the preparation of organic electroluminescent devices, both an effective improvement in device lifetime and a significant reduction in preparation costs can be achieved simultaneously.

[0053] This application also provides an organic electroluminescent device, including a first electrode, a second electrode, and an organic layer located between the first electrode and the second electrode, wherein the organic layer comprises the aforementioned deuterated compound or a deuterated compound prepared by the aforementioned preparation method.

[0054] In some preferred embodiments, the organic layer includes at least one of a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer; at least one of the hole injection layer, hole transport layer, electron blocking layer, light-emitting layer, hole blocking layer, electron transport layer, and electron injection layer contains the aforementioned deuterated compound or the deuterated compound prepared by the aforementioned preparation method.

[0055] In some preferred embodiments, the organic layer includes an electron blocking layer, and the electron blocking layer contains the aforementioned deuterated compound or the deuterated compound prepared by the aforementioned preparation method.

[0056] The following describes some of the specific functional layers in the organic electroluminescent device.

[0057] Substrate:

[0058] The substrate is typically located below the anode and can be made of plastic or glass, and can be rigid or flexible. The substrate has driving units that can drive the corresponding pixels to emit light.

[0059] anode:

[0060] Anodes typically need to meet requirements such as good conductivity, smooth surface, and resistance to cracking. They also have certain requirements for work function, mainly to match the hole injection layer and achieve the hole injection effect.

[0061] When using a top-emitting method (cathode-side light emission), the anode is a metal compound with a work function of 4.2 eV or higher, such as indium tin oxide, tin oxide, indium zinc oxide, gold, silver, platinum, copper, carbon nanotubes, carbon nanowires, graphene, etc. The thickness can range from 10 nm to 200 nm, preferably 10 nm to 50 nm. A reflective electrode is placed below the anode (near the substrate end). The reflective electrode is generally made of metal or metal alloy, such as silver, copper, aluminum, gold, or alloys of these metals with other metals. The reflective electrode has high reflectivity, requiring a reflectivity of over 90%, and its thickness is typically between 100 nm and 500 nm, preferably in the range of 80 nm to 150 nm.

[0062] When using a bottom-emitting method (substrate-side light emission), the anode is a metal compound with a work function of 4.2 eV or higher, such as indium tin oxide alloy, tin oxide, indium zinc oxide, gold, silver, platinum, copper, carbon nanotubes, carbon nanowires, graphene, etc. The thickness can be 10 nm to 1 μm, preferably 50 nm to 200 nm.

[0063] The anode can be made by forming a thin film from the electrode material using methods such as vapor deposition, sputtering, or coating.

[0064] Hole injection layer:

[0065] The thickness of the hole injection layer can range from 3 nm to 50 nm. The hole injection layer is a hybrid material of hole dopant and hole transport host material, wherein the mass percentage of hole dopant can be 1% to 5%.

[0066] The hole mobility of the hole transport host material is greater than or equal to that of N,N,N',N'-tetraphenylbenzidine diamine (CAS: 164724-35-0). The hole transport host material can be selected from the following group: Wherein: L1~L4, when present individually, are independently selected from single bonds or phenylene. Ar1~Ar4, when present individually, are independently selected from substituted or unsubstituted C6~C30 aryl groups, substituted or unsubstituted C3~C30 heteroaryl groups, and the substituents in the case of substitution are selected from C1~C10 alkyl groups. Preferably, Ar1~Ar4, when present individually, are independently selected from phenyl, biphenyl, dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazoyl, benzo[B]naphtho[2,3-D]furanyl, benzo[B]naphtho[1,2-D]furanyl, and benzo[B]naphtho[2,1-D]furanyl. When R1 and R2 are present individually, they are independently selected from substituted or unsubstituted C1-C10 alkyl groups, substituted or unsubstituted C6-C30 aryl groups, and substituted or unsubstituted C3-C30 heteroaryl groups, and the substituents in the case of substitution are selected from C1-C10 alkyl groups. R1 and R2 can also be bonded to form a ring.

[0067] In some specific embodiments, the hole transport host material may be selected from the following compounds:

[0068] .

[0069] The hole dopant can be selected from organic compounds or metal oxides.

[0070] In some preferred embodiments, the hole dopant is selected from compounds represented by Formula 1 or Formula 2: Formula 1 Equation 2; In Equation 1, R1~R 15 Each of the R1 to R2 is independently selected from fluorine, trifluoromethyl, cyano, and nitro. In Formula 2, each of R1 to R2 is independently selected from fluorinated aryl groups.

[0071] In some specific embodiments, the hole dopant is selected from the following compounds: , .

[0072] Hole transport layer:

[0073] The thickness of the hole transport layer can be 3nm to 150nm. The material selection can refer to the aforementioned hole transport host materials, which will not be repeated here.

[0074] Electron blocking layer:

[0075] The electron blocking layer can function as both a hole transport layer and an electron blocking layer. Furthermore, the higher triplet excitation level of the electron blocking layer can confine excitons generated in the emissive layer, thereby improving the device's luminous efficiency.

[0076] Emissive layer:

[0077] The thickness of the luminescent layer can be 30nm~40nm, 40nm~50nm, 50nm~60nm, 60nm~70nm, etc. Its materials typically include a host material and a dopant material, with the host material comprising a larger proportion than the dopant material. The host material's role is to promote the binding of electrons and holes to form electron-hole pairs, i.e., excitons, and to transfer the excitons' energy to the dopant material, thereby emitting light. This requires the host material to possess both considerable electron and hole mobility, as well as a certain triplet energy level.

[0078] In some embodiments, the luminescent host material may be selected from compounds containing carbazole and triazine groups, for example:

[0079] .

[0080] In other embodiments, to further improve the carrier transport balance of the light-emitting host material, two or more light-emitting host materials are used to form the light-emitting layer host by blending or co-evaporation. The host material primarily responsible for hole transport is called the p-host, and the host material primarily responsible for electron transport is called the n-host. The mass percentage of the p-host in the light-emitting host material can be selected from 30%~40%, 40%~50%, 50%~60%, 60%~70%, etc.

[0081] As an example, the p-host can be selected from the following compounds containing a carbazole group:

[0082] .

[0083] In some embodiments, the luminescent host material n-host may be selected from compounds containing triazine groups:

[0084] .

[0085] The luminescent guest material determines the emission wavelength and full width at half maximum (FWHM) of the device, i.e., the color of the light. The mass percentage of the luminescent guest material in the overall luminescent layer material can be selected from 3%~5%, 5%~8%, 8%~10%, 10%~15%, etc.

[0086] In some embodiments, the luminescent guest material is selected from the following metal complexes containing iridium and pyridine biphenyl groups:

[0087] Where L is selected from the following structures: ;R 100 Selected from hydrogen, substituted or unsubstituted C1-C30 alkyl groups, and substituted or unsubstituted C3-C30 cycloalkyl groups; R 101 To R 109 R 111 To R 123 Each is independently selected from hydrogen, deuterium, halogen, cyano, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C3-C30 cycloalkyl, substituted or unsubstituted C6-C30 aryl, substituted or unsubstituted C1-C30 alkoxy; R 106 To R 109 Adjacent substituents can connect to each other to form substituted or unsubstituted fused rings, for example, unsubstituted or alkyl-substituted fluorene, unsubstituted or alkyl-substituted dibenzothiophene, unsubstituted or alkyl-substituted dibenzofuran; and R 120 To R 123 Adjacent substituents can connect with each other to form substituted or unsubstituted fused rings, for example, unsubstituted or alkyl- or aryl-substituted quinolines; R 124 To R 127 Each is independently selected from hydrogen, deuterium, halogen, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C6-C30 aryl; and R 124 To R 127 Adjacent substituents can connect to each other to form substituted or unsubstituted fused rings, for example, unsubstituted or alkyl-substituted fluorene, unsubstituted or alkyl-substituted dibenzothiophene, unsubstituted or alkyl-substituted dibenzofuran; R 201 To R 211 Each is independently selected from hydrogen, deuterium, halogen, unsubstituted or halogen-substituted C1-C30 alkyl, substituted or unsubstituted C3-C30 cycloalkyl, substituted or unsubstituted C6-C30 aryl, and R 208 To R 211 Adjacent substituents can be linked to each other to form substituted or unsubstituted fused rings, for example, unsubstituted or alkyl-substituted fluorene, unsubstituted or alkyl-substituted dibenzothiophene, unsubstituted or alkyl-substituted dibenzofuran; f and g each independently represent integers from 1 to 3; where f or g is 2 or 3, R 100 Each of the elements can be the same or different; and n represents an integer from 1 to 3.

[0088] Cavity blocking layer:

[0089] To enhance the balance between hole and electron concentrations, a hole blocking layer is inserted to balance carrier concentration and prevent exciton quenching. Typically, the hole blocking layer is located between the emitting layer and the electron transport layer, and the hole blocking layer material must meet conditions such as high stability, good film-forming properties, and a sufficiently high highest molecular occupied orbital.

[0090] Electron transport layer:

[0091] The electron transport layer can be a single layer or multiple layers. As an example, the electron transport layer may include a first electron transport layer and / or a second electron transport layer. The thickness of the first electron transport layer can be 3nm~40nm, 3nm~10nm, 10nm~20nm, 20nm~30nm, 30nm~40nm, 20nm~40nm, etc. The material of each electron transport layer can be a single compound or a mixture with other metal compounds, such as a mixture with lithium 8-hydroxyquinoline.

[0092] The material for the first electron transport layer can be selected from the following triazine compounds: , Wherein, L1 is selected from single bond, phenyl, biphenyl, naphthyl; R1 is selected from hydrogen, phenyl, biphenyl; Ar1~Ar3 are independently selected from hydrogen, phenyl, 9,9-dimethylfluorenyl, 9,9-diphenylfluorenyl, 9,9-spirofluorenyl, 9,9-oxanthracenespirofluorenyl, phenanthrene.

[0093] As an example, the material for the first electron transport layer can be selected from the following group:

[0094] .

[0095] The thickness of the second electron transport layer can be 10 nm to 40 nm; the material of the second electron transport layer is selected from the following group: When L1 to L4 are present individually, they are independently selected from single bonds, phenyl, biphenyl, naphthyl, 9,9'-dimethylfluorenyl, and 9,9'-spirodifluorenyl; when Ar1 to Ar4 are present individually, they are independently selected from aryl groups with 6 to 50 substituted or unsubstituted carbon atoms, heteroaryl groups with 3 to 50 substituted or unsubstituted carbon atoms, and phosphonyl groups with substituted or unsubstituted carbon atoms.

[0096] As an example, the material of the second electron transport layer may be selected from the following group:

[0097] .

[0098] The second electron transport layer may also contain metals or metal compounds. For example, the metal compounds are alkali metal compounds, alkaline earth metal compounds, rare earth metal compounds, etc. More specifically, examples include lithium metal compounds, calcium metal compounds, magnesium metal compounds, samarium metal compounds, ytterbium metal compounds, etc. More concrete examples include lithium 8-hydroxyquinoline, lithium fluoride, magnesium fluoride, ytterbium fluoride, calcium fluoride, etc. When containing metal compounds, the mass percentage of the second electron transport material can be 20%~80%, 20%~40%, 40%~60%, 60%~80%, etc. When containing metals, such as alkali metals, alkaline earth metals, rare earth metals, etc., more concrete examples include lithium metal, magnesium metal, calcium metal, ytterbium metal, samarium metal, etc., the mass percentage of the second electron transport material can be 80%~99%, 80%~89%, 89%~99%, 80%~85%, 85%~90%, 90%~95%, or 95%~99%, etc.

[0099] Electron injection layer:

[0100] The electron injection layer can lower the potential barrier for electrons to be injected from the cathode into the organic layer, improve electron injection efficiency, and thus optimize device performance. The selection of materials for the electron injection layer needs to consider its work function matching with the cathode material, and can be selected from alkali metals, alkaline earth metals, rare earth metals, or their inorganic or coordination compounds.

[0101] cathode:

[0102] The cathode requires materials with good electrical conductivity and surface smoothness. To improve electron injection capability, materials with low work function are usually selected. Cathode materials can be single-layer, double-layer, or multi-layer cathodes, and are generally metals or metal alloys. For single-layer cathodes, silver, copper, aluminum, gold, or alloys of these metals with other metals, such as rare earth metals, alkali metals, and alkaline earth metals, can be used. Examples include magnesium-indium alloys, magnesium-aluminum alloys, aluminum-potassium alloys, aluminum-scandium-potassium alloys, magnesium-silver alloys, silver-ytterbium alloys, and silver-samarium alloys. If a double-layer metal cathode is used, the cathode layer closer to the light-emitting layer can be made of alkali metals, alkaline earth metals, or rare earth metals, such as lithium, calcium, magnesium, and ytterbium, to increase electron injection capability. The cathode layer farther from the light-emitting side is mainly used to improve conductivity, and generally uses silver, copper, aluminum, gold, or alloys of these metals with other metals, such as alloys with rare earth metals, alkali metals, or alkaline earth metals. Examples include magnesium-indium alloys, magnesium-aluminum alloys, aluminum-potassium alloys, aluminum-scandium-potassium alloys, magnesium-silver alloys, silver-ytterbium alloys, and silver-samarium alloys. The cathode can also be formed into a thin film using methods such as vapor deposition or sputtering.

[0103] Overlay:

[0104] When light exits from the cathode side, photons resonate with electrons in the cathode metal, reducing the light extraction efficiency. Adding a capping layer on the side of the cathode furthest from the light-emitting layer can reduce this effect and effectively improve the light efficiency. When adding a capping layer, a capping layer material with high refractive index and low absorption coefficient should be used directly. For example, a material with a refractive index greater than 1.9 and an absorption rate less than 0.01% at a wavelength of 460 nm is preferred, a material with a refractive index greater than 2.0 and an absorption rate less than 0.01% at a wavelength of 460 nm is preferred, and a material with a refractive index greater than 2.1 and an absorption rate less than 0.01% at a wavelength of 460 nm is even more preferred.

[0105] The preparation method and characteristics of the deuterated compounds of this application, as well as the characteristics of organic electroluminescent devices containing them, will be explained in detail below with reference to representative compounds of this application, so as to understand the technical solution of this application. However, the technical solution of this application is not limited to the following examples.

[0106] The initial raw materials and solvents used in the embodiments of this application were purchased from Sinopharm, and some commonly used OLED intermediates were purchased from domestic OLED intermediate manufacturers; palladium catalysts and ligands were purchased from Shaanxi Ruike New Materials Co., Ltd. LC-MS (liquid chromatography-mass spectrometry) was performed on a Waters Corporation UPLC+SQD2 instrument. Experimental methods in the following examples that do not specify specific conditions were generally determined according to national standards. If no corresponding national standard exists, general international standards, conventional methods and conditions, or conditions recommended by the manufacturer, or the product instructions, were followed. Unless otherwise specified, all percentages are weight percentages.

[0107] Deuterated compounds

[0108] Example 1

[0109] This embodiment provides a method for preparing compound 1, which is synthesized using the following route:

[0110] .

[0111] The specific preparation method includes the following steps:

[0112] (1) Preparation of compound C1

[0113] Under a nitrogen atmosphere, 1,3-dibromobenzene- was added sequentially to a dry three-necked flask. d4. Benzaldehyde (11.7 g, 110.0 mmol, 1.1 eq), 1,3-dimethylimidazolium iodide (2.2 g, 10.0 mmol, 0.1 eq), and anhydrous N,N'-dimethylformamide (DMF, 200 mL) were thoroughly mixed. Then, sodium hydride (2.6 g, 110.0 mmol, 1.1 eq) was added in four portions at 0 °C, and the reaction was continued at the same temperature for 30 minutes. The reaction mixture was then gradually heated to 50 °C and the reaction was continued for 24 hours. Thin-layer chromatography analysis showed that virtually no raw material remained. The reaction system was cooled to room temperature, and deionized water (150 mL) and ethyl acetate (400 mL) were added sequentially and stirred for 5 minutes. The mixture was then allowed to stand for separation, and the layers were separated using a separatory funnel. The organic phase was retained, and the aqueous phase was extracted with ethyl acetate (3 × 30 mL). The aqueous phase was combined with the retained organic phase, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum distillation. The crude product was separated by silica gel column chromatography (mobile phase: n-hexane / ethyl acetate mixed solvent) to give compound C1 (18.8 g, yield 70.9%).

[0114] (2) Preparation of compound C2

[0115] Under a nitrogen atmosphere, 2-bromobiphenyl (18.0 g, 77.0 mmol, 1.1 eq) and anhydrous tetrahydrofuran (350 mL) were added sequentially to a dry three-necked flask. After thorough mixing, n-butyllithium (2.5 M n-hexane solution, 33.6 mL, 84 mmol, 1.2 eq) was added dropwise at -40 °C. After the addition was complete, the reaction was continued at -40 °C for 1.5 h. Subsequently, compound C1 (18.6 g, 70.0 mmol, 1 eq) was added, and the reaction system was gradually restored to room temperature, and the reaction was continued for 1 h. Thin-layer chromatography analysis showed that there was essentially no reactant remaining. The reaction system was cooled to 0 °C, and the reaction was quenched by adding 30 mL of saturated ammonium chloride aqueous solution. Add ethyl acetate (200 mL) and stir for 5 minutes, then allow to stand for phase separation. Separate the layers using a separatory funnel, retaining the organic phase. Extract the aqueous phase with ethyl acetate (3 × 30 mL) and combine it with the previously retained organic phase. Dry the mixture over anhydrous magnesium sulfate, filter, and remove the solvent by vacuum distillation. The resulting crude product requires no further purification and can be used directly in the next reaction step.

[0116] (3) Preparation of compound C3

[0117] Under a nitrogen atmosphere, compound C2 (29.3 g, 70.0 mmol, 1 eq) and glacial acetic acid (400 mL) were added sequentially to a dry three-necked flask. After thorough mixing, the mixture was heated to 110 °C, followed by the dropwise addition of concentrated sulfuric acid (4 mL), and the reaction was continued for 5 hours. Thin-layer chromatography analysis showed that there was essentially no reactant remaining. The reaction system was cooled to 0 °C, and the reaction was quenched by the dropwise addition of saturated sodium bicarbonate solution (200 mL). Dichloromethane (500 mL) was added and stirred for 5 minutes, followed by standing to separate the layers. The layers were separated using a separatory funnel, and the organic phase was retained. The aqueous phase was extracted with dichloromethane (3 × 30 mL) and combined with the retained organic phase. The mixture was dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum distillation. The crude product was separated by silica gel column chromatography (mobile phase: n-hexane / dichloromethane mixed solvent) to give compound C3 (22.5 g, yield 90.1%).

[0118] (4) Preparation of compound 1

[0119] Under a nitrogen atmosphere, compound C3 (8.6 g, 24.0 mmol, 1 eq), compound C5-1 (8.6 g, 24.0 mmol, 1 eq), and degassed anhydrous toluene (120 mL) were added sequentially to a dry three-necked flask. After thorough mixing, sodium tert-butoxide (3.6 g, 36.0 mmol, 1.5 eq), dibenzylacetone palladium (139 mg, 0.24 mmol, 1% eq), and tri-tert-butylphosphine (1.2 mL, 0.48 mmol, 2% eq, in a 10% hexane solution) were added. The mixture was stirred to thoroughly mix the reaction system, and then heated to reflux under a nitrogen atmosphere. After 8 hours of reaction, thin-layer chromatography analysis showed that there was essentially no reactant remaining, and heating was stopped. After the reaction system cooled to room temperature, a mixture of 5 mL concentrated hydrochloric acid (37% aqueous solution) and 100 mL deionized water was added. The mixture was allowed to stand and separate into layers. The layers were separated using a separatory funnel, retaining the organic phase. The aqueous phase was extracted with toluene (3 × 15 mL) and combined with the retained organic phase. The solvent was removed by vacuum distillation. The crude product was then subjected to silica gel column chromatography (mobile phase: hexane / toluene mixture) and recrystallization (solvent: hexane / ethanol mixture) to obtain compound 1 (11.4 g, yield 69.6%). The overall yield of the four-step reaction was 44.5%, and the mass spectrometry (m / z) was 682.33 [M+H]. + .

[0120] Examples 2-8

[0121] Following the preparation method of Example 1, compounds 2-8 of Examples 2-8 were prepared respectively. The difference was that in the final step of the Buchwald coupling reaction, the secondary amine compound C5-1 in the reaction substrate was replaced by the corresponding secondary amine compound in an equivalent amount. The raw materials, structural formulas, overall yields and mass spectra are shown in Table 1.

[0122] Table 1. Raw materials, compound structural formulas, overall yield, and mass spectrometry.

[0123]

[0124]

[0125] It should be noted that the other compounds covered by Formula I of this application can be prepared by referring to the synthesis methods in the above-listed examples, and therefore will not be listed one by one here.

[0126] Comparative Example 1

[0127] This comparative example provides a method for preparing compound D1-1, which is synthesized using the following route:

[0128] .

[0129] The specific preparation method includes the following steps:

[0130] (1) Preparation of compound C6-1

[0131] The synthesis of compound C6-1 was completed by referring to the preparation method of compound 1 in step (4) of Example 1. The difference is that compound C3 was replaced by an equivalent amount of m-dibromobenzene, with a yield of 70.6%.

[0132] (2) Preparation of compound C7-1

[0133] Under a nitrogen atmosphere, compound C6-1 (20.7 g, 40.0 mmol, 1 eq), perfluorobutylsulfonic acid (2.4 g, 8.0 mmol, 0.2 eq), and deuterated benzene (400 mL) were added sequentially to a clean 1000 mL three-necked flask. The system was purged with nitrogen three times, and the reaction was heated to reflux and stirred for 5 days. Subsequently, the reaction was cooled, and most of the solvent was removed by vacuum distillation. Dichloromethane (200 mL) and a 10% sodium carbonate aqueous solution (50 mL) were added sequentially to the reaction system, and the mixture was stirred for half an hour. The mixture was separated. The mixture was washed once with water and dried. The organic phase was passed through a silica gel column and eluted with dichloromethane. The organic phase was evaporated to dryness, slurried with 50 mL of ethanol, filtered, and dried to obtain compound C7-1 (15.0 g, yield 69.1%).

[0134] (3) Preparation of compound C8-1

[0135] Under a nitrogen atmosphere, compound C7-1 (10.9 g, 20.0 mmol, 1 eq) and anhydrous tetrahydrofuran (100 mL) were added sequentially to a dry three-necked flask. After thorough mixing, n-butyllithium (2.5 M n-hexane solution, 9.6 mL, 24.0 mmol, 1.2 eq) was added dropwise at -40 °C. After the addition was complete, the reaction was continued at -40 °C for 1 hour. Subsequently, 2-biphenyl(phenyl)methyl ketone (6.2 g, 24.0 mmol, 1.2 eq) was added, and the reaction system was gradually restored to room temperature, and the reaction was continued for 1 hour. Thin-layer chromatography analysis showed that there was essentially no reactant remaining. The reaction system was cooled to 0 °C, and the reaction was quenched by adding 25 mL of saturated ammonium chloride aqueous solution. Add ethyl acetate (200 mL) and stir for 5 minutes, then allow to stand for phase separation. Separate the layers using a separatory funnel, retaining the organic phase. Extract the aqueous phase with ethyl acetate (3 × 30 mL) and combine it with the previously retained organic phase. Dry the mixture over anhydrous magnesium sulfate, filter, and remove the solvent by vacuum distillation. The resulting crude product requires no further purification and can be used directly in the next reaction step.

[0136] (4) Preparation of compound D1-1

[0137] Under a nitrogen atmosphere, compound C8-1 (14.4 g, 20.0 mmol, 1 eq) and glacial acetic acid (150 mL) were added sequentially to a dry three-necked flask. After thorough mixing, the mixture was heated to 110 °C, followed by the dropwise addition of concentrated sulfuric acid (1.5 mL), and the reaction was continued for 3 hours. Thin-layer chromatography analysis showed that there was essentially no reactant remaining. The reaction system was then cooled to 0 °C, and the reaction was quenched by the dropwise addition of saturated sodium bicarbonate solution (50 mL). Dichloromethane (200 mL) was added and stirred for 5 minutes, followed by standing to separate the layers. The layers were separated using a separatory funnel, and the organic phase was retained. The aqueous phase was extracted with dichloromethane (3 × 30 mL) and combined with the retained organic phase. The mixture was dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum distillation. The crude product was successively separated by silica gel column chromatography (mobile phase: hexane / toluene mixed solvent) and recrystallized (solvent: hexane / ethanol mixed solvent) to give compound D1-1 (11.6 g, yield 82.4%). The overall yield of the four-step reaction was 40.2%, and the mass spectrometry (m / z) was 704.47 [M+H]. + .

[0138] Comparative Examples 2-8

[0139] Following the preparation method of Comparative Example 1, compounds D2-1 to D8-1 of Comparative Examples 2 to 8 were prepared respectively. The difference was that in the first step of the Buchwald coupling reaction, the secondary amine compound C5-1 in the reaction substrate was replaced by the corresponding secondary amine compound in an equivalent amount. The structural formulas, overall yields, and mass spectrometry data of compounds D2-1 to D8-1 are shown in the table below.

[0140] Table 2. Structural formulas, overall yields, and mass spectra of compounds D2-1 to D8-1

[0141]

[0142]

[0143] Comparative Examples 9-16

[0144] Following the preparation method of compound D1-1, compounds D1-2 to D8-2 (comparative examples 9-16) were prepared respectively. The difference lies in that, in the first step of the Buchwald coupling reaction, the secondary amine compound C5-1 in the reaction substrate was replaced by an equivalent amount with the corresponding secondary amine compound, and the step of overall deuteration of the corresponding intermediate compound was omitted. The structural formulas, overall yields, and mass spectrometry data of compounds D1-2 to D8-2 are shown in the table below.

[0145] Table 3. Structural formulas, overall yields, and mass spectra of compounds D1-2 to D8-2

[0146]

[0147]

[0148] Organic electroluminescent devices

[0149] Example 9

[0150] refer to Figure 1 This embodiment provides a method for fabricating a green organic electroluminescent device, including the following steps:

[0151] (1) A mixture of compound M1 and compound M2 is vapor-deposited on the surface of the reflective anode 10 in a mass mixing ratio of 1:99 to form a hole injection layer 20 with a thickness of 10 nm.

[0152] (2) Compound M2 is vapor-deposited on the surface of hole injection layer 20 to form hole transport layer 30 with a thickness of 100 nm.

[0153] (3) Compound 1 prepared in Example 1 was vapor-deposited on the surface of hole transport layer 30 to form an electron blocking layer 40 with a thickness of 40 nm.

[0154] (4) The light-emitting host compounds M3-PG, M3-NG and the light-emitting guest compound M4-G are co-deposited in a mass ratio of 45:45:10 to form a light-emitting layer 50 with a thickness of 40 nm on the surface of the electron blocking layer 40.

[0155] (5) A hole blocking layer 60 with a thickness of 5 nm is formed by vapor deposition of compound M5 on the surface of the light-emitting layer 50.

[0156] (7) A mixture of compounds M6 and LiQ in a mass ratio of 4:6 is vapor-deposited on the surface of the hole blocking layer 60 to form an electron transport layer 70 with a thickness of 30 nm.

[0157] (8) A 5 nm electron injection layer 80 is formed by vapor deposition of ytterbium (Yb) on the surface of electron transport layer 70.

[0158] (9) Magnesium (Mg) and silver (Ag) are mixed and deposited on the surface of electron injection layer 80 at a vapor deposition rate of 1:9 to form a cathode 90 with a thickness of 14 nm.

[0159] The structural formulas of the compounds involved in the above preparation process are shown in the table below.

[0160] Table 4. Compound structural formulas

[0161]

[0162] Examples 10-16

[0163] The only difference from Example 9 is that, when forming the electron blocking layer 40, compounds 2-4 prepared in Examples 2-4 are used instead of compound 1.

[0164] Comparative Examples 17-20

[0165] The only difference from Example 9 is that, when forming the electron blocking layer 40, compounds D1-1 to D4-1 are used instead of compound 1.

[0166] Comparative Examples 21-24

[0167] The only difference from Example 9 is that, when forming the electron blocking layer 40, undeuterated compounds D1-2 to D4-2 are used instead of compound 1.

[0168] Device performance testing

[0169] Each set of examples and comparative examples was produced and tested in the same batch. The LT95 lifetime of the devices was tested under dark conditions using a Fostar lifetime measurement system equipped with a power supply and photodiode as detection units (test conditions: constant current 50mA / cm). 2 LT95 refers to the time required for the brightness to decrease from its initial brightness to 95%.

[0170] Table 5 Lifetime Test Results

[0171]

[0172] Example 13

[0173] Continue to refer to Figure 1This embodiment provides a method for fabricating a red organic electroluminescent device, including the following steps:

[0174] (1) A mixture of compound M1 and compound M2 is vapor-deposited on the surface of the reflective anode 10 in a mass mixing ratio of 1:99 to form a hole injection layer 20 with a thickness of 10 nm.

[0175] (2) Compound M2 is vapor-deposited on the surface of hole injection layer 20 to form hole transport layer 30 with a thickness of 100 nm.

[0176] (3) Compound 5 prepared in Example 5 was vapor-deposited on the surface of hole transport layer 30 to form an electron blocking layer 40 with a thickness of 80 nm.

[0177] (4) The host luminescent compound M3-R and the guest luminescent compound M4-R are co-deposited at a mass ratio of 95:5 to form a luminescent layer 50 with a thickness of 35 nm on the surface of the electron blocking layer 40.

[0178] (5) A hole blocking layer 60 with a thickness of 5 nm is formed by vapor deposition of compound M5 on the surface of the light-emitting layer 50.

[0179] (7) A mixture of compounds M6 and LiQ in a mass ratio of 4:6 is vapor-deposited on the surface of the hole blocking layer 60 to form an electron transport layer 70 with a thickness of 30 nm.

[0180] (8) A 5 nm electron injection layer 80 is formed by vapor deposition of ytterbium (Yb) on the surface of electron transport layer 70.

[0181] (9) Magnesium (Mg) and silver (Ag) are mixed and deposited on the surface of electron injection layer 80 at a vapor deposition rate of 1:9 to form a cathode 90 with a thickness of 14 nm.

[0182] The structural formulas of the compounds involved in the above preparation process are shown in Table 4.

[0183] Examples 14-16

[0184] The only difference from Example 13 is that, when forming the electron blocking layer 40, compounds 6-8 prepared in Examples 6-8 are used instead of compound 5.

[0185] Comparative Examples 25-28

[0186] The only difference from Example 13 is that, when forming the electron blocking layer 40, compounds D6-1 to D8-1 are used to replace compound 5.

[0187] Comparative Examples 29-32

[0188] The only difference from Example 13 is that, when forming the electron blocking layer 40, compounds D6-2 to D8-2 are used to replace compound 5.

[0189] Device performance testing

[0190] Each set of examples and comparative examples was produced and tested in the same batch. The LT95 lifetime of the devices was tested under dark conditions using a Fostar lifetime measurement system equipped with a power supply and photodiode as detection units (test conditions: constant current 50mA / cm). 2 LT95 refers to the time required for the brightness to decrease from its initial brightness to 95%.

[0191] Table 6 Lifetime Test Results

[0192]

[0193] The above device lifetime test results show that, compared with undeuterated compounds, the 9-position tetradeuterated compound provided in this application can effectively improve device lifetime and fully meet the requirements of actual products. Compared with HOMO fully deuterated compounds, the contribution of the "9-position tetradeuterated" compound in this application to the lifetime improvement can reach more than 30%.

[0194] As an example, compared to Comparative Example 21 (undeuterated), the device lifetime of Example 9 (9-position phenyl tetradeuterated, with 4 deuteration sites) was improved by 9.3%, and the device lifetime of Comparative Example 17 (HOMO fully deuterated, with 26 deuteration sites) was improved by 27.5%. Based on this calculation, the contribution of the "9-position phenyl tetradeuterated" in this application to the lifetime improvement relative to HOMO fully deuterated is approximately (9.3 / 27.5) × 100% = 33.8%. Similar effects are observed in the other example devices and comparative example devices, with this contribution reaching 31% to 38%.

[0195] Meanwhile, compared with the corresponding HOMO fully deuterated compounds, the device lifetime of the 9-position phenyl tetradeuterated compound of this application unexpectedly did not decrease proportionally with the decrease in the number of deuterium atoms. Taking Example 9 as an example, even when the number of deuteration sites was reduced by 84.6% ((26-4) / 26×100%), the device lifetime did not decrease proportionally by 84.6%.

[0196] It should be noted that, based on the methods described in the above embodiments, similar methods can be used to replace the compound used to prepare the electron blocking layer 40 with other compounds covered by Formula I of this application, thereby preparing the corresponding green or red organic electroluminescent devices. The green or red organic electroluminescent devices prepared by this type of substitution scheme can also achieve an effective improvement in device lifetime, and the relevant embodiments will not be described in detail in this application.

[0197] The preparation cost of deuterated compounds is a key factor restricting their large-scale application. The following comparison of the preparation costs of the "9-position phenyl tetradeuterated compound" and the comparative "HOMO fully deuterated compound" uses the preparation of compound 1 and compound D1-1 as examples. It should be noted that the reagent costs involved in non-deuterated steps are generally lower, and the cost difference between different schemes is small. However, the cost of deuteration steps is significantly higher than other synthetic steps. Therefore, when estimating costs, only the material costs of the key deuteration steps need to be compared. Tables 7 and 8 show the main material costs of the deuteration steps for compound 1 and compound D1-1, respectively.

[0198] Table 7. Main material costs of the initial step (introduction of deuterium atoms) of Compound 1

[0199]

[0200] Table 8. Main material costs for the deuteration step of compound D1-1

[0201]

[0202] As shown in Tables 7 and 8, when synthesizing target compounds of similar weight, the main material cost for the deuteration step in the preparation of compound 1 was 7237.5 yuan; while in the preparation of compound D1-1, the main material cost for the deuteration step was 20012 yuan. That is, the cost of the former is only 36% of that of the latter. Therefore, the 9-position phenyl tetradeuterated compound provided in this application can effectively reduce synthesis costs.

[0203] It should be noted that the above market price comparison is only an example. The actual market price is affected by the amount of deuterated reagent used. Moreover, with the development of the OLED industry and the improvement of material performance requirements, the market demand for deuterated compounds is becoming more and more urgent. The cost difference between the "9-position phenyl tetradeuterated compound" in this application and the "HOMO fully deuterated compound" in the comparative example may further widen.

[0204] The above comparison is between the deuteration method of this application and the deuteration route commonly used in the prior art. Even if both use the same deuteration method, since this application only needs to deuterate 4 sites, it can still significantly reduce the amount of deuteration reagent used, thereby significantly reducing the cost of the deuteration process.

[0205] The above comparison combines two concepts of this application: the first concept is to discover the unexpected properties of the 9-position phenyl tetradeuterated compound itself, and use this as a starting point to save on deuteration reagents; the second concept is to directly use the existing deuterated compound 1,3-dibromobenzene-d4, which has the target deuteration site required by this application, as the starting material for synthesis. This method does not require an additional deuteration step and can further reduce the amount of deuteration reagents used.

[0206] Furthermore, from a chemometric perspective, only one equivalent of 1,3-dibromobenzene needs to be added during the preparation of compound 1. d4 As a deuterium source, it can achieve a deuteration rate of nearly 100% at a specific position and generate very little deuterium-containing waste. However, in the preparation of compound D1-1, it is necessary to use tens of times the equivalent of deuterated benzene as a deuterium source, which not only results in low utilization of deuterium atoms but also generates a large amount of deuterium-containing waste.

[0207] Furthermore, the preparation of compound D1-1 suffers from long reaction times (several days) and the need to maintain high temperature and high pressure conditions for an extended period. In contrast, compound 1 has a shorter preparation cycle and milder reaction conditions. Therefore, the 9-position phenyl tetradeuterated compound provided in this application has significant advantages in terms of simple synthesis process, environmental friendliness, and low cost.

[0208] The above description of the embodiments is intended to enable those skilled in the art to understand and apply this application. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without creative effort. Therefore, this application is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope and spirit of this application are within the scope of this application.

Claims

1. A deuterated compound, characterized in that, Its structural formula is shown in Formula I: ； Formula I In Formula I, L1 and L2 are each independently selected from single-bonded, substituted or unsubstituted C6-C12 arylene, or substituted or unsubstituted C3-C12 heteroarylene. At least one of Ar1 and Ar2 is 9,9-dimethylfluorenyl, and the remainder is selected from substituted or unsubstituted C6-C18 aryl or substituted or unsubstituted C6-C18 heteroaryl. L1, L2, Ar1, and Ar2 are each independently either unsubstituted or substituted; when substituted, the substituents are selected from C1-C5 alkyl groups and C6-C12 aryl groups.

2. The deuterated compound according to claim 1, characterized in that, In Equation I: L1 and L2 are each independently selected from single bonds, substituted or unsubstituted phenylene, substituted or unsubstituted biphenylene; and / or, at least one of Ar1 and Ar2 is 9,9-dimethylfluorenyl, and the remainder is selected from substituted or unsubstituted phenyl, substituted or unsubstituted biphenyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted dibenzothiopheneyl; and / or, L1, L2, Ar1 and Ar2 are each independently unsubstituted or substituted; when substituted, the substituent is selected from methyl, ethyl, tert-butyl, phenyl, biphenyl.

3. The deuterated compound according to claim 2, characterized in that, In Equation I: L1 and L2 are independently selected from single bonds, phenylene, and biphenylene; At least one of Ar1 and Ar2 is 9,9-dimethylfluorenyl, and the rest are selected from phenyl, biphenyl, terphenyl, dibenzofuranyl, and dibenzothiopheneyl.

4. The deuterated compound according to claim 3, characterized in that, The deuterated compounds are selected from the following group: ； Wherein, L1 is selected from single bond, phenylene, and biphenylene; Ar1 ​​is selected from phenyl, biphenyl, terphenyl, dibenzofuranyl, dibenzothiophene, and 9,9-dimethylfluorenyl.

5. The deuterated compound according to any one of claims 1 to 3, characterized in that, The deuterated compounds are selected from the following group: 。 6. A method for preparing a deuterated compound, characterized in that, include: The first compound is obtained by reacting 1,3-dihalobenzene-d4 with benzaldehyde; the structural formula of the first compound is as follows. X1 is selected from chlorine, bromine, and iodine; The first compound is reacted with a halobiphenyl to give a second compound; the structural formula of the second compound is as follows: ; The second compound undergoes an intramolecular dehydration reaction to yield a third compound; the structural formula of the third compound is as follows: ; The third and fourth compounds undergo a Buchwald-Hartwig coupling reaction to yield the deuterated compound as described in claim 1; the fourth compound has the following structural formula: The definitions of L1, L2, Ar1 and Ar2 are the same as in claim 1.

7. The method for preparing the deuterated compound according to claim 6, characterized in that, The structural formula of the 1,3-dihalophenyl-d4 is as follows: X is selected from chlorine, bromine, and iodine, and the reactivity of X is not lower than that of X1. The structural formula of the halobiphenyl is: X2 is selected from chlorine, bromine, and iodine.

8. The method for preparing the deuterated compound according to claim 6, characterized in that, The Buchwald-Hartwig coupling reaction satisfies at least one of the following conditions (a) to (c): (a) The catalyst is selected from palladium compounds, the auxiliary ligand is selected from phosphine ligands, and the reaction system is alkaline; (b) The solvent used is selected from at least one of benzene, toluene, xylene, and chlorobenzene; (c) The reaction temperature is the reflux temperature, and the reaction time is 5 to 10 hours.

9. Use of the deuterated compound according to any one of claims 1 to 5 in the preparation of organic electroluminescent devices.

10. An organic electroluminescent device, characterized in that, It includes a first electrode, a second electrode, and an organic layer located between the first electrode and the second electrode, wherein the organic layer comprises a deuterated compound as described in any one of claims 1 to 5.

11. The organic electroluminescent device according to claim 10, characterized in that, The organic layer includes an electron blocking layer, and the electron blocking layer contains the deuterated compound according to any one of claims 1 to 5.

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