Deuterated compound, preparation method and application thereof, and organic electroluminescent device

Abstract

The invention discloses a deuterated compound, a preparation method and application of the deuterated compound and an organic electroluminescent device, and relates to the field of organic electroluminescent materials, and the structural formula of the deuterated compound is shown in the formula I; in the formula I, L1 and L2 are each independently selected from a single bond, a substituted or unsubstituted arylene of C6-C12, and a substituted or unsubstituted heteroarylene of C3-C12; at least one of Ar1 and Ar2 is 9, 9-dimethyl fluorenyl, and the rest of Ar1 and Ar2 are selected from substituted or unsubstituted aryl of C6-C18 and substituted or unsubstituted heteroaryl of C6-C18; l1, L2, Ar1 and Ar2 are each independently an unsubstituted condition or a substituted condition; and in the case of substitution, the substituent group is selected from C1-C5 alkyl groups and C6-C12 aryl groups. The deuterated compound can effectively prolong the service life of the device and consider the cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic electroluminescent materials, in particular to a deuterated compound, a preparation method, use and an organic electroluminescent device thereof. BACKGROUND

[0002] Organic light-emitting device (OLED) has many advantages such as low driving voltage, high luminance and luminous efficiency, wide viewing angle, fast response speed, relatively simple manufacturing process and the like, and has attracted extensive attention from the academic and industrial circles.

[0003] Although the research on organic electroluminescent devices has made significant progress, as the market continues to expand and deepen, the performance requirements are constantly improving, among which the device lifetime problem is particularly prominent. Therefore, how to effectively improve the device lifetime has become a long-term concern and in-depth research topic in the academic and industrial circles. At present, the industry generally improves the device lifetime by improving the deuterium substitution degree of the material, but this method often accompanies a high synthesis cost. Therefore, in the usual way in the industry, the deuterium substitution strategy is usually used to improve the device lifetime at the cost of sacrificing part of the cost, which makes the deuterated compound face significant economic challenges in large-scale application. SUMMARY

[0004] The technical problem solved by the present application is how to effectively improve the lifetime of an organic electroluminescent device under the premise of low cost.

[0005] To solve the above technical problem, the present application provides the following technical solutions: In a first aspect, the present application provides a deuterated compound, the structural formula of which is shown as formula I: Formula I; in formula I, L1 and L2 are each independently selected from a single bond, a substituted or unsubstituted C6-C12 arylene group, a substituted or unsubstituted C3-C12 heteroarylene group; at least one of Ar1 and Ar2 is a 9,9-dimethylfluorenyl group, and the rest is selected from a substituted or unsubstituted C6-C18 aryl group, a substituted or unsubstituted C6-C18 heteroaryl group; L1, L2, Ar1 and Ar2 are each independently in an unsubstituted state or a substituted state; if in the substituted state, the substituent is selected from a C1-C5 alkyl group and a C6-C12 aryl group.

[0006] In a second aspect, the present application provides a preparation method of a deuterated compound, comprising: reacting 1,3-dihalobenzene-d4 with benzaldehyde to obtain a first compound; the structural formula of the first compound is wherein X1 is selected from chlorine, bromine and iodine; reacting the first compound with halogenated biphenyl to obtain a second compound; the structural formula of the second compound is ; subjecting the second compound to intramolecular dehydration to obtain a third compound; the structural formula of the third compound is ; subjecting the third compound and a fourth compound to Buchwald-Hartwig coupling reaction to obtain the deuterated compound according to the first aspect; the structural formula of the fourth compound is: , wherein the definitions of L1, L2, Ar1 and Ar2 are the same as those in the first aspect.

[0007] In a third aspect, the present application provides a use of the deuterated compound according to the first aspect or the deuterated compound prepared by the preparation method according to the second aspect in the preparation of an organic electroluminescent device.

[0008] In a fourth aspect, the present application provides an organic electroluminescent device comprising a first electrode, a second electrode and an organic layer between the first electrode and the second electrode, and the organic layer comprises the deuterated compound according to the first aspect or the deuterated compound prepared by the preparation method according to the second aspect.

[0009] Compared with the prior art, the technical scheme of the present application has the following beneficial effects: The deuterated compound of the present application takes 9,9-diphenylfluorene as a basic skeleton, replaces any one of the two phenyl groups at the 9-position of the fluorene group with an arylamine group at the 3-position, and replaces the remaining four hydrogen atoms on the phenyl group with deuterium atoms. Through this design, only a few specific positions need to be deuterated, which can effectively improve the device lifetime and meet the actual application requirements, thereby breaking the traditional cognition that the improvement of the lifetime of the organic electroluminescent device is positively correlated with the degree of deuteration of the material. At the same time, the deuterated compound greatly reduces the deuteration cost, realizes the consideration of lifetime improvement and cost control, breaks through the dilemma in the prior art that the improvement of the lifetime by the deuteration strategy needs to sacrifice the cost, and has outstanding industrialization value.

[0010] In addition, the preparation method of the deuterated compound of the present application synthesizes the existing deuterated compound having the target deuterated site required by the present application as a starting material, without the need for additional deuteration steps. Not only can the high deuteration rate of the target deuterated position be ensured, but the amount of deuterated reagent can also be further reduced, significantly reducing the generation of deuterated waste. The synthesis process is simple, environmentally friendly and low-cost, and has good potential for large-scale production and application. BRIEF DESCRIPTION OF DRAWINGS

[0011] The following drawings detail the exemplary embodiments disclosed in the present application. Identical reference numerals in several views of the drawings represent similar structures. Those skilled in the art will understand that these embodiments are non-limiting, exemplary embodiments, and the drawings are for illustrative and descriptive purposes only and are not intended to limit the scope of the present application, and other ways of embodiments can also achieve the same intent of the invention in the present application. It should be understood that the drawings are not drawn to scale. Among them: Figure 1 Structure diagram of an organic electroluminescent device prepared for Example 9 and Example 13 of the present application. DETAILED DESCRIPTION

[0012] The following description provides specific application scenarios and requirements of the present application, in order to enable those skilled in the art to manufacture and use the contents of the present application. Various local modifications of 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 the present application.

[0013] Deuterium (D) is a stable form of non-radioactive isotope in nature, due to its larger atomic mass than hydrogen, so that the bond length of C-D bond is short, the bond energy is large, and the C-D bond is about 6-9 times more stable than C-H bond. If deuterium atoms are introduced into OLED materials, the molecular structure can be stabilized, the light-emitting efficiency and stability of OLED devices can be significantly improved, and the service life can be prolonged. And according to industry experience, the higher the degree of deuteration, the more conducive to improving the device life (cumulative enhancement effect of deuteration effect), and it is best to achieve full deuteration, so that the device life reaches the best.

[0014] Research results show that the gradual deuteration of the host material has a cumulative enhancement effect on the device lifetime, and the highly deuterated host material can increase the lifetime by more than four times, and this deuteration strategy is universal in extending the lifetime of all OLED materials (Cumulative Lifetime Enhancement Effect of Deuteration in Blue OLEDs. International Conference on Display Technology 2023 (Volume 54, Issue S1).). Related research also discloses the relationship between the degree of deuteration and the service life of the device. By increasing the number of deuterium atoms in an organic electron donor material (PNA) from 5 to 22, the LT90 device lifetime is increased from 8.2 hours to 33.6 hours, and the device lifetime is extended by four times. Therefore, the increase in lifetime is proportional to the degree of deuteration of the host molecule (Lifetime Enhancement and Degradation Study of Blue OLEDs Using Deuterated Materials. ACS Appl. Mater. Interfaces 2023, 15, 7255-7262.). However, the higher the degree of deuteration, the more deuterium reagents are required, and multiple deuterations are usually required to increase the degree of deuteration, resulting in long synthesis cycle, high cost, and a large amount of deuterated waste, which is not environmentally friendly. If the deuteration strategy is used to improve the device lifetime, it usually means sacrificing part of the cost, which has become the usual way of thinking in the industry.

[0015] However, the inventors of the present application unexpectedly found that 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 group") in the 9,9-diphenylfluorene structure is substituted with an arylamine group, only the remaining four hydrogen atoms on the "9-position phenyl group" need to be replaced with deuterium atoms (hereinafter referred to as "9-position phenyl tetra-deuterated"), which can effectively improve the device lifetime of the entire compound (hereinafter referred to as "9-position phenyl tetra-deuterated compound") molecule.

[0016] Compared with the compound which is fully deuterated with the "9-phenyl" and "arylamine group" (hereinafter referred to as "HOMO fully deuterated compound"), the device lifetime of the 9-phenyl tetra-deuterated compound does not decrease proportionally with the decrease of the number of deuterium atoms, which is different from the viewpoint disclosed in the prior art that the increase of the device lifetime is proportional to the degree of deuteration of the host molecule. If the increase of the device lifetime of the HOMO fully deuterated compound relative to the non-deuterated compound is taken as 100%, the contribution of the "9-phenyl tetra-deuterated" to the increase of the device lifetime can reach more than 30%. The reason may be that the lone pair electrons of the nitrogen atom in the "arylamine group" increase the electron cloud density of the "9-phenyl", thereby enhancing the chemical activity thereof. Therefore, the substitution of the remaining four hydrogen atoms on the "9-phenyl" with deuterium atoms can effectively improve the bond energy and enhance the stability of the whole molecule, thereby benefiting the increase of the device lifetime.

[0017] At the same time, compared with the HOMO fully deuterated compound, the preparation cost of the 9-phenyl tetra-deuterated compound greatly decreases with the decrease of the deuteration site. Thus, the contradiction between the increase of the device lifetime and the decrease of the preparation cost is effectively alleviated.

[0018] Based on this, the embodiment of the present application provides a deuterated compound, the structural formula of which is shown as formula I: Formula I.

[0019] In formula I, L1 and L2 are each independently selected from a single bond, a substituted or unsubstituted C6-C12 arylene group, and a substituted or unsubstituted C3-C12 heteroarylene group. At least one of Ar1 and Ar2 is a 9,9-dimethylfluorenyl group, and the rest is selected from a substituted or unsubstituted C6-C18 aryl group and a substituted or unsubstituted C6-C18 heteroaryl group. L1, L2, Ar1 and Ar2 are each independently in an unsubstituted state or a substituted state; if in the substituted state, the substituent is selected from a C1-C5 alkyl group and a C6-C12 aryl group.

[0020] Unless otherwise specified, "a certain group of Cn-Cm" in the present application refers to a certain group having n to m carbon atoms. For example, "a C6-C12 arylene group" refers to an arylene group having 6 to 12 carbon atoms.

[0021] Unless otherwise specified, "aryl" in the present application can be a monocyclic aryl group or a polycyclic aryl group; the monocyclic aryl group includes but is not limited to a phenyl group, a tolyl group and the like; the polycyclic aryl group includes a fused ring aryl group, a biphenyl type aryl group and a polycycloalkyl group, wherein the fused ring aryl group includes but is not limited to a naphthyl group, an anthryl group, a phenanthryl group, a fluorenyl group and the like, the biphenyl type aryl group is, for example, a biphenyl group, and the polycycloalkyl group is a structure formed by connecting a plurality of aryl rings through an alkyl group, for example, a diphenylmethyl group ( ) ; the * in the structural formula in the present application represents a connection site.

[0022] Unless otherwise specified, "aryl" as used herein refers to a divalent group formed by removing two hydrogen atoms from an aromatic hydrocarbon molecule, which can also be regarded as a divalent group formed by removing one hydrogen atom from an aryl group; in addition to being a divalent group, its definition can apply the relevant description of aryl as described above, for example, arylene, methylenephenylene, biphenylylene, naphthylene, anthrylene, phenanthrylene, fluorenylene, etc.

[0023] Unless otherwise specified, "heteroaryl" as used herein refers to an aryl group comprising at least one of B, N, O, P, S, Si, and Se, which includes but is not limited to pyridyl, pyrrolyl, pyrimidinyl, pyridazinyl, furanyl, thiophenyl, imidazolyl, pyrazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, triazolyl, diazolyl, thiadiazolyl, tetrazolyl, pyrazinyl, thiazinyl, triazinyl, tetrazinyl, quinolinyl, isoquinolinyl, indolyl, indolizinyl, phthalazinyl, pyridopyrimidinyl, pyridopyrazinyl, pyrazinopyrazinyl, benzothiazolyl, benzoxazolyl, benzimidazolyl, benzothiophenyl, benzofuranyl, dibenzofuranyl, dibenzothiophenyl, imidazopyridinyl, phenanthrolinyl, imidazophenanthridinyl, naphthyridinyl, quinazolinyl, quinoxalinyl, etc.

[0024] Unless otherwise specified, "heteroaryl" as used herein refers to an aryl group comprising at least one of B, N, O, P, S, Si, and Se, which includes but is not limited to pyridyl, pyrrolyl, pyrimidinyl, pyridazinyl, furanyl, thiophenyl, imidazolyl, pyrazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, triazolyl, diazolyl, thiadiazolyl, tetrazolyl, pyrazinyl, thiazinyl, triazinyl, tetrazinyl, quinolinyl, isoquinolinyl, indolyl, indolizinyl, phthalazinyl, pyridopyrimidinyl, pyridopyrazinyl, pyrazinopyrazinyl, benzothiazolyl, benzoxazolyl, benzimidazolyl, benzothiophenyl, benzofuranyl, dibenzofuranyl, dibenzothiophenyl, imidazopyridinyl, phenanthrolinyl, imidazophenanthridinyl, naphthyridinyl, quinazolinyl, quinoxalinyl, etc.

[0025] Unless otherwise specified, "alkyl" as used herein can be a straight chain or branched structure, for example, methyl, ethyl, propyl (n-propyl, isopropyl), butyl (n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl), pentyl (n-pentyl, isopentyl, neopentyl, tert-pentyl).

[0026] ​In some preferred embodiments, L1and L2are each independently selected from a single bond, substituted or unsubstituted phenylene, substituted or unsubstituted biphenylene; L1and L2are each independently in the unsubstituted case or in the substituted case; if in the substituted case, the substituents are preferably selected from methyl, ethyl, t-butyl, phenyl, biphenyl. More preferably, L1and L2are independently selected from a single bond, phenylene, biphenylene. In some specific embodiments, L1is selected from a single bond, phenylene, biphenylene; L2is a single bond.

[0027] In some preferred embodiments, at least one of Ar1and Ar2is 9,9-dimethylfluorenyl, and the rest is selected from substituted or unsubstituted phenyl, substituted or unsubstituted biphenyl, substituted or unsubstituted dibenzofuranyl, substituted or unsubstituted dibenzothiophenyl; Ar1and Ar2are each independently in the unsubstituted case or in the substituted case; if in the substituted case, the substituents are preferably selected from methyl, ethyl, t-butyl, phenyl, biphenyl. More preferably, at least one of Ar1and Ar2is 9,9-dimethylfluorenyl, and the rest is selected from phenyl, biphenyl, terphenyl, dibenzofuranyl, dibenzothiophenyl.

[0028] In some embodiments, the deuterated compound is selected from the group consisting of: ; wherein, L1is selected from a single bond, phenylene, biphenylene; Ar1is selected from phenyl, biphenyl, terphenyl, dibenzofuranyl, dibenzothiophenyl, 9,9-dimethylfluorenyl.

[0029] In some embodiments, the deuterated compound is selected from the group consisting of: .

[0030] In some more specific embodiments, the deuterated compound is selected from the group consisting of: .

[0031] The embodiments of the present application also provide a preparation method of the deuterated compound, which synthesizes the deuterated compound with the target deuterium substitution site required by the present application as a starting material without additional deuterium substitution steps. This scheme not only can achieve a high deuterium substitution rate of the target deuterium substitution site, but also can further reduce the amount of deuterium reagent, significantly reduce the generation of deuterium waste, and thus make the production process have more significant environmental protection and cost advantages.

[0032] The method for preparing the deuterated compound of the embodiments of the present application comprises the following steps: S1: reacting 1,3-dihalobenzene-d4 with benzaldehyde to obtain a first compound; the structural formula of the first compound is , wherein X1 is selected from chlorine, bromine, iodine; S2: reacting the first compound with halogenated biphenyl to obtain a second compound; the structural formula of the second compound is ; S3: subjecting the second compound to intramolecular dehydration to obtain a third compound; the structural formula of the third compound is ; S4: subjecting the third compound and a fourth compound to Buchwald-Hartwig coupling reaction to obtain the aforementioned deuterated compound; the structural formula of the fourth compound is: , wherein L1, L2, Ar1 and Ar2 are as defined above.

[0033] In some preferred embodiments, in step S1, the structural formula of the 1,3-dihalobenzene-d4 is ; wherein X is selected from chlorine, bromine, iodine, and the reactivity of X is not lower than the reactivity of X1. As an example, both X and X1 are bromine; or, X is bromine and X1 is chlorine; or, X is iodine and X1 is bromine.

[0034] In some preferred embodiments, in step S1, the reaction temperature is 0-50°C, and the reaction time is 20-30 hours.

[0035] In some preferred embodiments, in step S2, the structural formula of the halogenated biphenyl is , wherein X2 is selected from chlorine, bromine, iodine.

[0036] In some preferred embodiments, in step S2, the reaction temperature is -40-30°C, and the reaction time is 2-5 hours.

[0037] In some preferred embodiments, in step S3, the reaction temperature is 100-120°C, and the reaction time is 2-8 hours.

[0038] In some preferred embodiments, in step S4, when the Buchwald-Hartwig coupling reaction is performed, the catalyst is selected from palladium compounds, the auxiliary ligand is selected from phosphine ligands, and the reaction system is alkaline.

[0039] In some preferred embodiments, in step S4, when the Buchwald-Hartwig coupling reaction is performed, the solvent used is selected from at least one of benzene, toluene, xylene, chlorobenzene.

[0040] In some preferred embodiments, in step S4, the reaction temperature is the reflux temperature, and the reaction time is 5-10 hours.

[0041] When the 9-phenyl tetra-deuterated compound of the present application is used to prepare an organic electroluminescent device, on the one hand, the improvement of the overall stability of the molecule can significantly improve the service life of the device; on the other hand, the reduction of deuterated sites can greatly reduce the preparation cost of the compound itself. Further, in the preparation of the 9-phenyl tetra-deuterated compound of the present application, the existing deuterated compound with the desired target deuterated site of the present application can be directly used as the starting material for synthesis, without the need for additional deuterated steps. This not only ensures a high deuterium enrichment rate at the target deuterium site, but also reduces the amount of deuterated reagent, thereby further reducing the preparation cost. Therefore, when the deuterated compound of the present application or the deuterated compound prepared by the preparation method of the present application is applied to the preparation of an organic electroluminescent device, the effective improvement of the service life of the device and the significant reduction of the preparation cost can be achieved simultaneously.

[0042] The present application also provides an organic electroluminescent device, which comprises a first electrode, a second electrode, and an organic layer between the first electrode and the second electrode, and the organic layer comprises the aforementioned deuterated compound or the deuterated compound prepared by the aforementioned preparation method.

[0043] In some preferred embodiments, the organic layer comprises 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, the hole transport layer, the electron blocking layer, the light-emitting layer, the hole blocking layer, the electron transport layer, and the electron injection layer contains the aforementioned deuterated compound or the deuterated compound prepared by the aforementioned preparation method.

[0044] In some more preferred embodiments, the organic layer comprises an electron blocking layer, and the electron blocking layer contains the aforementioned deuterated compound or the deuterated compound prepared by the aforementioned preparation method.

[0045] The following describes some specific functional layers in the organic electroluminescent device.

[0046] Substrate: The substrate is generally located below the anode and can be plastic or glass, rigid or bendable. The substrate has a driving unit that can drive the corresponding pixels to emit light.

[0047] Anode: The anode generally needs to meet the requirements of good electrical conductivity, smooth surface, and resistance to cracking, etc. At the same time, it also has certain requirements for the work function, mainly being able to match the hole injection layer to play the hole injection effect.

[0048] When top emission (cathode side light out) is used, the anode is made of 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 nanotube, carbon nanowire, graphene, etc. The thickness can be 10 nm to 200 nm, preferably 10 nm to 50 nm. A reflective electrode is provided below the anode (close to the substrate end), which is generally made of a metal or metal alloy, such as silver metal, copper metal, aluminum metal, gold metal, or an alloy of these metals with other metals. The reflective electrode has a high reflectivity, with a reflectivity of 90% or higher, and a thickness of generally 100 nm to 500 nm, preferably 80 nm to 150 nm.

[0049] When bottom emission (substrate side light out) is used, the anode is made of 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 nanotube, carbon nanowire, graphene, etc. The thickness can be 10 nm to 1 μm, preferably 50 nm to 200 nm.

[0050] The anode can be made by forming a thin film of the electrode material by evaporation, sputtering, coating, or the like.

[0051] Hole injection layer: The thickness of the hole injection layer can be 3 nm to 50 nm. The hole injection layer is made of a mixture of a hole dopant and a hole transport host material, with the mass fraction of the hole dopant being 1% to 5%.

[0052] The hole transport host material has a hole mobility greater than or equal to N,N,N',N'-quaterphenylphenyldiamine (CAS: 164724-35-0). The hole transport host material can be selected from the following group: ; wherein: L1-L4, when present, are each independently selected from a single bond or a phenylene group. Ar1-Ar4, when present, are each independently selected from a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C3-C30 heteroaryl group, and the substituents, when present, are selected from a C1-C10 alkyl group. Preferably, Ar1-Ar4, when present, are each independently selected from a phenyl group, a biphenyl group, a dimethylfluorenyl group, a dibenzofuranyl group, a dibenzothiophenyl group, an N-phenylcarbazolyl group, a benzo[B]naphtho[2,3-D]furanyl group, a benzo[B]naphtho[1,2-D]furanyl group, a benzo[B]naphtho[2,1-D]furanyl group. R1 and R2, when present, are each independently selected from a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C3-C30 heteroaryl group, and the substituents, when present, are selected from a C1-C10 alkyl group. R1 and R2 can also be bonded to form a ring.

[0053] In some embodiments, the hole-transporting host material can be selected from the following compounds: .

[0054] The hole-dopant can be selected from organic compounds or metal oxides.

[0055] In some preferred embodiments, the hole-dopant is selected from the following compounds of Formula 1 or Formula 2: Formula 1, Formula 2; in Formula 1, R1~R 15 each is independently selected from fluorine, trifluoromethyl, cyano, nitro. In Formula 2, R1~R2are each independently selected from fluorine-containing aryl groups.

[0056] In some embodiments, the hole-dopant is selected from the following compounds: 、 .

[0057] Hole-transporting layer: The thickness of the hole-transporting layer can be 3 nm~150 nm, and the material selection can refer to the aforementioned hole-transporting host materials, which will not be repeated here.

[0058] Electron-blocking layer: The electron-blocking layer can have both hole-transporting and electron-blocking functions. Meanwhile, the higher triplet excitation energy level of the electron-blocking layer can confine the excitons generated in the light-emitting layer in the light-emitting layer, thereby improving the light-emitting efficiency of the device.

[0059] Light-emitting layer: The thickness of the light-emitting layer can be 30 nm~40 nm, 40 nm~50 nm, 50 nm~60 nm, 60 nm~70 nm, etc., and the material thereof usually includes a light-emitting host material and a light-emitting dopant material, wherein the content of the light-emitting host material is greater than that of the light-emitting dopant material. The role of the light-emitting host material is to promote the combination of electrons and holes to form electron-hole pairs, i.e., excitons, and to transfer the energy of the excitons to the light-emitting dopant material, thereby emitting light. This requires the light-emitting host material to have a certain electron and hole mobility, as well as a certain triplet energy level.

[0060] In some embodiments, the light-emitting host material can be selected from compounds containing a carbazole group and a triazine group, for example: .

[0061] In other embodiments, in order to further improve the carrier transport balance of the light-emitting host material, two or more light-emitting host materials are adopted to form the light-emitting layer host in a blended or co-evaporated manner. Among them, the host material mainly responsible for hole transport is called p-host, and the host material mainly responsible for electron transport is called n-host. The mass fraction of p-host in the light-emitting host material can be selected from 30% to 40%, 40% to 50%, 50% to 60%, 60% to 70%, etc.

[0062] As an example, the p-host can be selected from the following compounds containing a carbazole group:

[0063] In some embodiments, the light-emitting host material n-host can be selected from the following compounds containing a triazine group: .

[0064] The light-emitting guest material determines the emission wavelength and half-width of the device, i.e., the color light. The mass fraction of the light-emitting guest material in the overall light-emitting layer material can be selected from 3% to 5%, 5% to 8%, 8% to 10%, 10% to 15%, etc.

[0065] In some embodiments, the light-emitting guest material is selected from the following metal complexes containing iridium and a pyridyl biphenyl group: ; wherein L is selected from the following structures: ; R 100 is selected from hydrogen, substituted or unsubstituted C1-C30 alkyl, and substituted or unsubstituted C3-C30 cycloalkyl; R 101 to R 109 , R 111 to R 123 are each 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, and substituted or unsubstituted C1-C30 alkoxy; R 106 to R 109 Adjacent substituents of R to R can be linked to each other to form a substituted or unsubstituted fused ring, for example, unsubstituted or alkyl-substituted fluorene, unsubstituted or alkyl-substituted dibenzothiophene, and unsubstituted or alkyl-substituted dibenzofuran; and R 120 to R 123 Adjacent substituents of R to R can be linked to each other to form a substituted or unsubstituted fused ring, for example, unsubstituted or alkyl- or aryl-substituted quinoline; R 124 to R 127are each 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 may be linked to each other to form a substituted or unsubstituted fused ring, for example, unsubstituted or alkyl-substituted fluorene, unsubstituted or alkyl-substituted dibenzothiophene, unsubstituted or alkyl-substituted dibenzofuran; R 201 to R 211 are each 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 may be linked to each other to form a substituted or unsubstituted fused ring, for example, unsubstituted or alkyl-substituted fluorene, unsubstituted or alkyl-substituted dibenzothiophene, unsubstituted or alkyl-substituted dibenzofuran; f and g each independently represent an integer from 1 to 3; wherein f or g is 2 or 3, R 100 Each of them may be the same or different; and n represents an integer of 1 to 3.

[0066] Hole blocking layer: To enhance the balance between hole and electron concentrations, a hole-blocking layer is inserted to balance carrier concentrations and prevent exciton quenching. Typically, the hole-blocking layer is located between the light-emitting layer and the electron-transporting layer. The hole-blocking layer material must meet requirements such as high stability, good film-forming properties, and a high maximum molecular orbital.

[0067] Electron transport layer: The electron transport layer can be a single layer or a multilayer. As an example, the electron transport layer can 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 mixed with other metal compounds, for example, mixed with 8-hydroxyquinoline lithium.

[0068] The material of the first electron transport layer can be selected from the following s-triazine compounds: 、 ; Wherein, L1 is selected from a 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-xanthenespirofluorenyl, and phenanthryl.

[0069] As an example, the material of the first electron transport layer can be selected from the following group:

[0070] 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: ; wherein each of L1 to L4, when present, is independently selected from a single bond, phenyl, biphenyl, naphthyl, 9,9'-dimethylfluorenyl, 9,9'-spirobifluorenyl; each of Ar1 to Ar4, when present, is independently selected from a substituted or unsubstituted aryl group having 6 to 50 carbon atoms, a substituted or unsubstituted heteroaryl group having 3 to 50 carbon atoms, a substituted or unsubstituted phosphinyl group.

[0071] As an example, the material of the second electron transport layer can be selected from the following group: .

[0072] The second electron transport layer can further comprise a metal or a metal compound. For example, the metal compound is an alkali metal compound, an alkaline earth metal compound, a rare earth metal compound, etc. More specifically, for example, a lithium metal compound, a calcium metal compound, a magnesium metal compound, a samarium metal compound, a ytterbium metal compound, etc. More specifically, for example, lithium 8-hydroxyquinolinate, lithium fluoride, magnesium fluoride, ytterbium fluoride, calcium fluoride, etc. When the metal compound is included, the mass ratio of the second electron transport material can be 20% to 80%, 20% to 40%, 40% to 60%, 60% to 80%, etc. When the metal is included, for example, an alkali metal, an alkaline earth metal, a rare earth metal, etc., more specifically, for example, lithium metal, magnesium metal, calcium metal, ytterbium metal, samarium metal, etc., the mass ratio of the second electron transport material can be 80% to 99%, 80% to 89%, 89% to 99%, 80% to 85%, 85% to 90%, 90% to 95%, or 95% to 99%, etc.

[0073] The electron injection layer: The electron injection layer can reduce the potential barrier of the electrons injected from the cathode to the organic layer, improve the electron injection efficiency, and thus optimize the performance of the device. The material selection of the electron injection layer needs to consider the matching degree of the work function with the cathode material, and can be selected from an alkali metal, an alkaline earth metal, a rare earth metal, or an inorganic compound or a coordination compound thereof.

[0074] The cathode: The cathode needs a material with good electrical conductivity and good surface flatness. In order to improve the electron injection capability, a material with small work function is usually selected. The cathode material can be a single-layer cathode or a double-layer or multi-layer cathode, and generally is a metal or a metal alloy. For a single-layer cathode, silver, copper, aluminum, gold or an alloy of these metals with other metals, such as an alloy with rare earth metals, alkali metals, alkaline earth metals, can be used, for example, magnesium-indium alloy, magnesium-aluminum alloy, aluminum-potassium alloy, aluminum-scandium-potassium alloy, magnesium-silver alloy, silver-ytterbium alloy, silver-samarium alloy, etc. If a double-layer metal is used for the cathode, the cathode close to the light-emitting layer side can use alkali metals, alkaline earth metals, rare earth metals, etc. to increase the electron injection capability, such as lithium, calcium, magnesium, ytterbium, etc., and the cathode layer far from the light-emitting side is mainly to improve the electrical conductivity, which can use silver, copper, aluminum, gold or an alloy of these metals with other metals, such as an alloy with rare earth metals, alkali metals, alkaline earth metals, can be used, for example, magnesium-indium alloy, magnesium-aluminum alloy, aluminum-potassium alloy, aluminum-scandium-potassium alloy, magnesium-silver alloy, silver-ytterbium alloy, silver-samarium alloy, etc. The cathode can also be formed into a thin film by evaporation, sputtering or other methods.

[0075] Covering layer: When light comes out from the cathode side, the photons interact with the electrons in the cathode metal to reduce the light output efficiency. Adding a covering layer on the side of the cathode far from the light-emitting layer can reduce this effect and effectively improve the light efficiency. When a covering layer is added, a high refractive index and low absorption coefficient covering layer material is directly used, for example, a material with a refractive index greater than 1.9 at a wavelength of 460 nm and an absorption rate less than 0.01%, preferably a material with a refractive index greater than 2.0 at a wavelength of 460 nm and an absorption rate less than 0.01%, more preferably a material with a refractive index greater than 2.1 at a wavelength of 460 nm and an absorption rate less than 0.01%.

[0076] The preparation method of the deuterated compounds of the present application and the properties thereof, and the properties of the organic electroluminescent devices comprising the same will be explained in detail below in combination with representative compounds of the present application, so as to understand the technical solutions of the present application, but the technical solutions of the present application are not limited to the following examples.

[0077] The initial raw materials and solvents of the embodiments of the present application are purchased from China Pharmaceutical, and some commonly used OLED intermediates are purchased from domestic OLED intermediate manufacturers; if palladium catalyst, ligand, etc. are involved, they are purchased from Shaanxi Ruikexin Material Co., Ltd. LC-MS (liquid chromatography-mass spectrometry) is tested on the UPLC+SQD2 model instrument of Waters Corporation. The experimental methods in the following examples without specific conditions are generally determined according to the national standards. If there is no corresponding national standard, the general international standard, the conventional method and condition, or the condition suggested by the manufacturer, or the commodity instruction is selected. Unless otherwise specified, all percentages are weight percentages.

[0078] Deuterated compounds Example 1 This example provides a method for preparing compound 1, which is synthesized using the following route:

[0079] .

[0080] The specific preparation method comprises the following steps: (1) Preparation of compound C1 Under nitrogen atmosphere, 1,3-dibromobenzene- d 4 (24.0 g, 100.0 mmol, 1 eq), 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. The reaction was continued at the same temperature for 30 minutes. The reaction system was then gradually heated to 50°C and the reaction continued for 24 hours. Thin-layer chromatography analysis revealed virtually no residual starting material. 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 and separated using a separatory funnel. The organic phase was retained, and the aqueous phase was extracted with ethyl acetate (3 × 30 mL). This phase was combined with the retained organic phase, dried over anhydrous magnesium sulfate, filtered, and the solvent removed by reduced pressure distillation. The resulting crude product was separated by silica gel column chromatography (mobile phase: a mixture of n-hexane and ethyl acetate) to afford compound C1 (18.8 g, 70.9% yield).

[0081] (2) Preparation of compound C2 To a dry three-necked flask, under nitrogen atmosphere, was added 2-bromobiphenyl (18.0 g, 77.0 mmol, 1.1 eq) and anhydrous tetrahydrofuran (350 mL) successively. After thorough mixing, n-butyllithium (2.5 M in n-hexane, 33.6 mL, 84 mmol, 1.2 eq) was added dropwise at -40 °C, and the reaction was continued at -40 °C for 1.5 hours after the addition was completed. Compound C1 (18.6 g, 70.0 mmol, 1 eq) was then added, and the reaction was gradually returned to room temperature and continued for 1 hour. After the reaction was analyzed by thin layer chromatography and found to be substantially complete, the reaction was quenched by the dropwise addition of saturated aqueous ammonium chloride solution (30 mL) at 0 °C. Ethyl acetate (200 mL) was added and stirred for 5 minutes, and then allowed to separate into layers, and the organic phase was retained, and the aqueous phase was extracted with ethyl acetate (3 x 30 mL), combined with the previously retained organic phase, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by distillation under reduced pressure. The resulting crude product was used directly in the next reaction without further purification.

[0082] (3) Preparation of compound C3 To a dry three-necked flask, under nitrogen atmosphere, was added compound C2 (29.3 g, 70.0 mmol, 1 eq) and glacial acetic acid (400 mL) successively. After thorough mixing, the reaction was heated to 110 °C, and then concentrated sulfuric acid (4 mL) was added dropwise, and the reaction was continued for 5 hours. After the reaction was analyzed by thin layer chromatography and found to be substantially complete, the reaction was quenched by the dropwise addition of saturated sodium bicarbonate solution (200 mL) at 0 °C. Dichloromethane (500 mL) was added and stirred for 5 minutes, and then allowed to separate into layers, and the organic phase was retained, and the aqueous phase was extracted with dichloromethane (3 x 30 mL), combined with the previously retained organic phase, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by distillation under reduced pressure. The crude product was separated by column chromatography on silica gel (mobile phase: n-hexane / dichloromethane mixed solvent) to obtain compound C3 (22.5 g, yield 90.1 %).

[0083] (4) Preparation of compound 1 To a dry three-necked flask, under nitrogen atmosphere, were added 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) successively, after thorough mixing, sodium tert-butoxide (3.6 g, 36.0 mmol, 1.5 eq), bis(dibenzylideneacetone)palladium (139 mg, 0.24 mmol, 1% eq) and tri-tert-butylphosphine (1.2 mL, 10% in n-hexane, 0.48 mmol, 2% eq) were added successively. The stirring was started, the reaction system was thoroughly mixed and heated to reflux under nitrogen atmosphere. After 8 hours of reaction, TLC analysis showed that the starting material was almost consumed, the heating was stopped. When the reaction system temperature dropped to room temperature, a mixture of 5 mL concentrated hydrochloric acid (37% in water) and 100 mL deionized water was added, the mixture was allowed to stand and separate into two layers, the organic phase was retained, the aqueous phase was extracted with toluene (3 x 15 mL), the combined organic phase was concentrated under reduced pressure, the crude product was separated by silica gel column chromatography (mobile phase: n-hexane / toluene mixture) and recrystallized (solvent: n-hexane / ethanol mixture) successively to obtain compound 1 (11.4 g, yield 69.6%), total yield of four steps 44.5%, mass (m / z) = 682.33 [M+H] + .

[0084] Examples 2-8 Referring to the preparation method of Example 1, compounds 2-8 of Examples 2-8 were prepared respectively, except that in the last step of Borchwald coupling reaction, the secondary amine compound C5-1 in the reaction substrate was replaced by the corresponding secondary amine compound in equal amount. The raw materials, structural formula, total yield and mass spectrum are shown in Table 1.

[0085] Table 1 Raw materials, compound structural formula, total yield and mass spectrum

[0086]

[0087] It should be noted that other compounds covered by Formula I in the present application can be prepared by referring to the synthesis methods in the above-mentioned examples, so they are not listed one by one here.

[0088] Comparative Example 1 This comparative example provides a preparation method of compound D1-1, which is synthesized by the following route: .

[0089] The specific preparation method includes the following steps: (1) Preparation of compound C6-1 The synthesis of compound C6-1 was accomplished according to the procedure described in the preparation of compound 1 in step (4) of Example 1. The difference is that m-dibromobenzene was used to replace compound C3 in equimolar amount. The yield was 70.6%.

[0090] (2) Preparation of compound C7-1 Into a clean 1000 mL three-necked flask, 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 successively under nitrogen atmosphere. The system was replaced by nitrogen for 3 times, and the reaction was heated to reflux and stirred for 5 days. Then the reaction was cooled down, and most of the solvent was removed by distillation under reduced pressure. Dichloromethane (200 mL) and 10% sodium carbonate aqueous solution (50 mL) were added successively to the reaction system, stirred for half an hour, and then separated. The aqueous phase was washed once more, and dried. The organic phase was passed through a silica gel column, and eluted with dichloromethane. The organic phase was rotary evaporated, slurried with 50 mL of ethanol, filtered, and dried to obtain compound C7-1 (15.0 g, yield 69.1%).

[0091] (3) Preparation of compound C8-1 Into a dry three-necked flask, compound C7-1 (10.9 g, 20.0 mmol, 1 eq) and anhydrous tetrahydrofuran (100 mL) were added successively under nitrogen atmosphere. After thorough mixing, n-butyllithium (2.5 M in n-hexane, 9.6 mL, 24.0 mmol, 1.2 eq) was added dropwise at -40 °C. After the addition was completed, the reaction was continued at -40 °C for 1 hour. Then 2-biphenyl(phenyl)methanone (6.2 g, 24.0 mmol, 1.2 eq) was added, and the reaction system was gradually returned to room temperature and continued to react for 1 hour. The reaction was quenched by dropwise addition of saturated ammonium chloride aqueous solution (25 mL) at 0 °C after the analysis by thin layer chromatography showed that the starting material was substantially consumed. Ethyl acetate (200 mL) was added and stirred for 5 minutes, and then the reaction was allowed to stand and separate into two layers. The organic phase was retained, and the aqueous phase was extracted with ethyl acetate (3 x 30 mL), combined with the previously retained organic phase, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by distillation under reduced pressure. The crude product was used directly in the next step without further purification.

[0092] (4) Preparation of compound D1-1 To a dry three-necked flask, compound C8-1 (14.4 g, 20.0 mmol, 1 eq) and glacial acetic acid (150 mL) were added successively under nitrogen atmosphere. After thoroughly mixed, the temperature was raised to 110 °C, followed by dropwise addition of concentrated sulfuric acid (1.5 mL) and the reaction was continued for 3 hours. After the reaction was substantially completed by thin layer chromatography analysis, the reaction system was cooled to 0 °C and quenched by dropwise addition of saturated sodium bicarbonate solution (50 mL). Dichloromethane (200 mL) was added and stirred for 5 minutes, followed by standing and separation of layers with a separatory funnel. The organic phase was retained and the aqueous phase was extracted with dichloromethane (3 x 30 mL), combined with the previously retained organic phase, dried over anhydrous magnesium sulfate, filtered, and the solvent was removed by distillation under reduced pressure. The crude product was separated by silica gel column chromatography (mobile phase: n-hexane / toluene mixed solvent) and recrystallization (solvent: n-hexane / ethanol mixed solvent) successively to obtain compound D1-1 (11.6 g, yield 82.4%), total yield of four steps 40.2%, mass spectrum (m / z) = 704.47 [M+H] + .

[0093] Comparative Examples 2-8 Compound D2-1-D8-1 of Comparative Examples 2-8 were prepared according to the preparation method of Comparative Example 1, respectively. The difference is that in the first step of the Buchwald coupling reaction, the secondary amine compound C5-1 in the reaction substrate is replaced by the corresponding secondary amine compound in equivalent amount. The structural formula, total yield and mass spectrum data of compound D2-1-D8-1 are as follows.

[0094] Table 2 Structural formula, total yield and mass spectrum of compound D2-1-D8-1

[0095]

[0096] Comparative Examples 9-16 Compound D1-2-D8-2 of Comparative Examples 9-16 were prepared according to the preparation method of compound D1-1, respectively. The difference is that in the first step of the Buchwald coupling reaction, the secondary amine compound C5-1 in the reaction substrate is replaced by the corresponding secondary amine compound in equivalent amount, and the step of overall deuterium substitution of the corresponding intermediate compound is omitted. The structural formula, total yield and mass spectrum data of compound D1-2-D8-2 are as follows.

[0097] Table 3 Structural formula, total yield and mass spectrum of compound D1-2-D8-2

[0098]

[0099] Organic electroluminescent device Example 9 Reference Figure 1 The embodiment provides a preparation method of a green organic electroluminescent device, which comprises the following steps: (1) A mixed material of compound M1 and compound M2 is evaporated on the surface of the reflective anode 10 at a mass mixing ratio of 1:99 to form a hole injection layer 20 with a thickness of 10 nm.

[0100] (2) Compound M2 is evaporated on the surface of the hole injection layer 20 to form a hole transport layer 30 with a thickness of 100 nm.

[0101] (3) Compound 1 prepared in the embodiment 1 is evaporated on the surface of the hole transport layer 30 to form an electron blocking layer 40 with a thickness of 40 nm.

[0102] (4) A light-emitting host compound M3-PG, M3-NG and a light-emitting guest compound M4-G are co-evaporated on the surface of the electron blocking layer 40 at a mass ratio of 45:45:10 to form a light-emitting layer 50 with a thickness of 40 nm.

[0103] (5) Compound M5 is evaporated on the surface of the light-emitting layer 50 to form a hole blocking layer 60 with a thickness of 5 nm.

[0104] (7) Compound M6 and LiQ with a mixing mass ratio of 4:6 are evaporated on the surface of the hole blocking layer 60 to form an electron transport layer 70 with a thickness of 30 nm.

[0105] (8) Ytterbium (Yb) is evaporated on the surface of the electron transport layer 70 to form an electron injection layer 80 with a thickness of 5 nm.

[0106] (9) Magnesium (Mg) and silver (Ag) are mixed and deposited on the surface of the electron injection layer 80 at a deposition rate of 1:9 to form a cathode 90 with a thickness of 14 nm.

[0107] The compound structure formula involved in the above preparation process is shown in the following table.

[0108] Table 4 Compound structure formula

[0109] Embodiments 10-16 The difference from the embodiment 9 is that the compound 2-4 prepared in the embodiments 2-4 is respectively used instead of the compound 1 when the electron blocking layer 40 is formed.

[0110] Comparative examples 17-20 The difference from the embodiment 9 is that the compound D1-1-D4-1 is respectively used instead of the compound 1 when the electron blocking layer 40 is formed.

[0111] Comparative examples 21-24 The difference from Example 9 is that, when forming the electron blocking layer 40, the non-deuterated compounds D1-2~D4-2 are used instead of compound 1, respectively.

[0112] Device performance test Each group of examples and comparative examples is produced and tested in the same batch. The LT95 lifetime of the device in dark condition (test condition: constant current 50 mA / cm2) is tested using a Fudan lifetime measurement system equipped with a power supply and a photodiode as a detection unit. 2 LT95 refers to the time required for the luminance to decrease to 95% of the initial luminance.

[0113] Table 5 Lifetime test results

[0114] Example 13 With reference to the foregoing Figure 1 , this embodiment provides a preparation method of a red organic electroluminescent device, comprising the following steps: (1) A mixed material of compound M1 and compound M2 with a mass mixing ratio of 1:99 is evaporated on the surface of the reflective anode 10 to form a hole injection layer 20 with a thickness of 10 nm.

[0115] (2) Compound M2 is evaporated on the surface of the hole injection layer 20 to form a hole transport layer 30 with a thickness of 100 nm.

[0116] (3) Compound 5 prepared in Example 5 is evaporated on the surface of the hole transport layer 30 to form an electron blocking layer 40 with a thickness of 80 nm.

[0117] (4) The light-emitting host compound M3-R and the light-emitting guest compound M4-R are co-evaporated on the surface of the electron blocking layer 40 with a mass ratio of 95:5 to form a light-emitting layer 50 with a thickness of 35 nm.

[0118] (5) Compound M5 is evaporated on the surface of the light-emitting layer 50 to form a hole blocking layer 60 with a thickness of 5 nm.

[0119] (7) Compound M6 and LiQ with a mixing mass ratio of 4:6 are evaporated on the surface of the hole blocking layer 60 to form an electron transport layer 70 with a thickness of 30 nm.

[0120] (8) Ytterbium (Yb) is evaporated on the surface of the electron transport layer 70 to form an electron injection layer 80 with a thickness of 5 nm.

[0121] (9) Magnesium (Mg) and silver (Ag) are mixed and deposited on the surface of the electron injection layer 80 with a deposition rate of 1:9 to form a cathode 90 with a thickness of 14 nm.

[0122] The structural formulas of the compounds involved in the above preparation process are shown in Table 4.

[0123] Examples 14-16 The only difference from Example 13 is that when forming the electron blocking layer 40 , Compounds 6 to 8 prepared in Examples 6 to 8 are used instead of Compound 5.

[0124] Comparative Examples 25-28 The only difference from Example 13 is that when forming the electron blocking layer 40 , compounds D6-1 to D8-1 are used instead of compound 5.

[0125] Comparative Examples 29-32 The only difference from Example 13 is that when forming the electron blocking layer 40 , compounds D6-2 to D8-2 are used instead of compound 5.

[0126] Device performance test Each set of examples and comparative examples were produced and tested in the same batch. A Foster life measurement system equipped with a power supply and a photodiode as a detection unit was used to test the LT95 life of the device under dark conditions (test conditions: constant current 50mA / cm 2 LT95 refers to the time required for the brightness to decrease from the initial brightness to 95%.

[0127] Table 6 Life test results

[0128] The device lifespan test results above demonstrate that the tetradeuterated 9-phenyl compound provided in this application can effectively improve device lifespan compared to the undeuterated compound, fully meeting the requirements of actual products. Compared to fully deuterated HOMO compounds, the tetradeuterated 9-phenyl compound in this application contributes over 30% to the lifetime improvement.

[0129] As an example, compared to Comparative Example 21 (non-deuterated), the device lifetime of Example 9 (tetradeuterated phenyl at position 9, with four deuterated sites) increased by 9.3%, and the device lifetime of Comparative Example 17 (fully deuterated HOMO, with 26 deuterated sites) increased by 27.5%. Based on this calculation, the contribution of the "tetradeuterated phenyl at position 9" of this application to the lifetime improvement relative to fully deuterated HOMO is approximately (9.3 / 27.5) × 100% = 33.8%. Similar effects were observed in the other groups of Example devices and Comparative Example devices, with contributions ranging from 31% to 38%.

[0130] Furthermore, compared to the corresponding fully deuterated HOMO compounds, the device lifetime of the tetradeuterated 9-phenyl compound of the present application surprisingly did not decrease proportionally with the reduction in the number of deuterium atoms. Taking Example 9 as an example, even when the number of deuterated sites was reduced by 84.6% ((26-4) / 26 × 100%), the device lifetime did not decrease proportionally by 84.6%.

[0131] It should be noted that based on the methods described in the above embodiments, a method similar to the embodiments can be used to replace the compound used to prepare the electron blocking layer 40 with other compounds covered by Formula I of the present application, thereby preparing a corresponding green or red organic electroluminescent device. The green or red organic electroluminescent device prepared by such a replacement scheme can also effectively improve the device lifespan, and the relevant embodiments will not be described in detail in this application.

[0132] The preparation cost of deuterated compounds is a key factor restricting their large-scale application. Taking the preparation of compound 1 and compound D1-1 as an example, the preparation cost of the "9-phenyl tetradeuterated compound" of the present application is compared with the "HOMO full deuterated compound" of the comparative example. It should be noted that the reagent cost involved in the non-deuterated step is generally low, the cost gap between different schemes is small, and the cost of the deuterated step is significantly higher than that of other synthesis steps. Therefore, when estimating the cost, it is only necessary to compare the material cost of the key deuterated step. Table 7 and Table 8 show the main material costs of the deuterated step of compound 1 and compound D1-1, respectively.

[0133] Table 7 Cost of main materials used in the initial step (introduction of deuterium atoms) of compound 1

[0134] Table 8 Cost of main materials used in the deuteration step of compound D1-1

[0135] As can be seen from Tables 7 and 8, when synthesizing target compounds of similar weight, the cost of the main materials used in the deuteration step of Compound 1 was 7,237.5 yuan; while the cost of the main materials used in the deuteration step of Compound D1-1 was 20,012 yuan, that is, the cost of the former was only 36% of the latter. This shows that the 9-phenyl tetradeuterated compounds provided by this application can effectively reduce synthesis costs.

[0136] 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. With the development of the OLED industry and the improvement of material performance requirements, the market demand for deuterated compounds is becoming more urgent. The cost difference between the "9-position phenyl tetradeuterated compound" of this application and the "HOMO fully deuterated compound" of the comparative example may further expand.

[0137] The above comparison is a comparison between the deuterium substitution method of the present application and the deuterium substitution route commonly used in the prior art. Even if the same deuterium substitution method is used, since the present application only needs to deuterate 4 sites, the amount of deuterium reagent can be greatly reduced, thereby significantly reducing the cost of the deuterium substitution step.

[0138] The above comparison combines two concepts of the present application: the first concept is to find the unexpected properties of the 9-phenyl tetra-deuterated compound itself, and to use this as a starting point to save deuterium reagents; the second concept is to directly use the existing deuterated compound 1,3-dibromobenzene-d4 with the target deuterium substitution sites required by the present application as the starting material for synthesis, which does not need to add additional deuterium substitution steps, and can further reduce the amount of deuterium reagent used.

[0139] At the same time, from the perspective of stoichiometry, only 1 equivalent of 1,3-dibromobenzene-d4 is needed in the preparation of compound 1. d4 As a deuterium source, it can achieve a deuterium substitution rate of nearly 100% at a specific position, and generate very little deuterium-containing waste; while in the preparation of compound D1-1, dozens of equivalents of deuterated benzene are used as a deuterium source, not only the utilization rate of deuterium atoms is low, but also a large amount of deuterium-containing waste is generated.

[0140] In addition, the preparation of compound D1-1 also has the problems of long reaction time (several days) and the need to maintain high temperature and high pressure conditions for a long time. In comparison, the preparation of compound 1 has a shorter preparation period and milder reaction conditions. Therefore, the 9-phenyl tetra-deuterated compound provided by the present application has the significant advantages of simple synthesis process, environmental protection and low cost.

[0141] The above description of the embodiments is to facilitate those of ordinary skill in the art to understand and apply the present application. Those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described herein to other embodiments without having to exert creative labor. Therefore, the present application is not limited to the embodiments herein, and the improvements and modifications made by those skilled in the art based on the disclosure of the present application without departing from the scope and spirit of the present application are within the scope of the present 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 a single bond, a substituted or unsubstituted C6-C12 arylene group, or a substituted or unsubstituted C3-C12 heteroarylene group; At least one of Ar1 and Ar2 is 9,9-dimethylfluorenyl, and the others 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 and C6-C12 aryl.

2. The deuterated compound according to claim 1, characterized in that In Formula 1: L1 and L2 are each independently selected from a single bond, a substituted or unsubstituted phenylene group, or a substituted or unsubstituted biphenylene group; and / or, at least one of Ar1 and Ar2 is a 9,9-dimethylfluorenyl group, and the others are selected from a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted dibenzofuranyl group, or a substituted or unsubstituted dibenzothiophenyl group; and / or, L1, L2, Ar1 and Ar2 are each independently unsubstituted or substituted; if substituted, the substituent is selected from a methyl group, an ethyl group, a tert-butyl group, a phenyl group, or a biphenyl group.

3. The deuterated compound according to claim 2, characterized in that In Formula 1: L1 and L2 are independently selected from a single bond, a phenylene group, and a biphenylene group; At least one of Ar1 and Ar2 is 9,9-dimethylfluorenyl, and the others are selected from phenyl, biphenyl, terphenyl, dibenzofuranyl, and dibenzothiophenyl.

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

5. The deuterated compound according to any one of claims 1 to 3, characterized in that The deuterated compound is selected from the group consisting of: 。 6. A method for preparing a deuterated compound, characterized in that: include: 1,3-dihalobenzene-d4 is reacted with benzaldehyde to obtain a first compound; the structural formula of the first compound is , wherein X1 is selected from chlorine, bromine, and iodine; The first compound is reacted with a halogenated biphenyl to obtain a second compound; the structural formula of the second compound is ; The second compound undergoes an intramolecular dehydration reaction to obtain a third compound; the structural formula of the third compound is ; The third compound and the fourth compound undergo a Buchwald-Hartwig coupling reaction to obtain the deuterated compound according to any one of claims 1 to 5; the structural formula of the fourth compound is: , wherein L1, L2, Ar1 and Ar2 are defined the same as in claim 1.

7. The method for preparing a deuterated compound according to claim 6, wherein: The structural formula of the 1,3-dihalogenated benzene-d4 is ; wherein X is selected from chlorine, bromine, and iodine, and the reactivity of X is not less than the reactivity of X1; The structural formula of the halogenated biphenyl is , wherein X2 is selected from chlorine, bromine, and iodine.

8. The method for preparing a deuterated compound according to claim 6, wherein: 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 at least one selected from benzene, toluene, xylene, and chlorobenzene; (c) The reaction temperature is reflux temperature, and the reaction time is 5 hours to 10 hours.

9. Use of the deuterated compound according to any one of claims 1 to 5 or the deuterated compound prepared by the preparation method according to any one of claims 6 to 8 in the preparation of an organic electroluminescent device.

10. An organic electroluminescent device, characterized in that: The invention comprises 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 deuterated compound according to any one of claims 1 to 5 or the deuterated compound prepared by the preparation method according to any one of claims 6 to 8.

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 or the deuterated compound prepared by the preparation method according to any one of claims 6 to 8.

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