Organic electroluminescent device

Abstract

The invention discloses an organic light-emitting device which comprises a first electrode, a second electrode, an organic layer and a covering layer structure, the organic layer comprises a light-emitting layer, and the light-emitting layer comprises a compound shown in the formula I: # imgabs0 # substituent Ar1 is selected from non-deuterated phenanthryl, partially deuterated phenanthryl or completely deuterated phenanthryl; a substituent group Ar2 is selected from partially deuterated or fully deuterated phenyl and partially deuterated or fully deuterated naphthyl; only one of the substituent group Ar1 and the substituent group Ar2 can generate dihedral angle change of more than 180 degrees relative to anthryl at normal temperature and normal pressure; the covering layer structure comprises a first covering layer and a second covering layer, the refractive index of the first covering layer is lower than that of the second covering layer, and the first covering layer comprises a fluorine-free compound and / or a fluorine-containing compound. The organic light-emitting device provided by the invention has relatively high efficiency and relatively long service life.

Description

Technical Field

[0001] The present application relates to the technical field of organic light-emitting devices, and in particular to an organic electroluminescent device. Background Art

[0002] In OLED devices, the performance of blue fluorescent devices is poor compared to phosphorescent red and green devices, which has become a shortcoming of OLED display technology. In order to improve the performance of blue fluorescent devices, some researchers have applied phenanthrene-containing fluorescent host materials to blue fluorescent devices, which has improved the device performance to a certain extent, but it still cannot meet current needs, so the performance of blue fluorescent devices still needs to be further improved. Summary of the invention

[0003] The purpose of this application is to further improve the performance of blue fluorescent devices so that they have both higher efficiency and lifespan.

[0004] To achieve the above objectives, this application provides the following technical solutions:

[0005] The present application provides an organic electroluminescent device, comprising: a first electrode, a second electrode, an organic layer and a covering layer structure; the organic layer is located between the first electrode and the second electrode and comprises a light-emitting layer, and the light-emitting layer comprises a compound represented by the following formula I:

[0006]

[0007] Wherein, the substituent Ar1 bonded to the 9-position of the anthracene group is selected from an undeuterated phenanthryl group, a partially deuterated phenanthryl group or a fully deuterated phenanthryl group; the substituent Ar2 bonded to the 10-position of the anthracene group is selected from a partially deuterated phenyl group or a partially deuterated naphthalene group or a fully deuterated naphthalene group; and among the substituent Ar1 and the substituent Ar2, only one substituent can change the dihedral angle by more than 180 degrees relative to the anthracene group at room temperature and pressure;

[0008] The covering layer structure includes a first covering layer located on the second electrode and a second covering layer located on the first covering layer, wherein the refractive index of the first covering layer is lower than that of the second covering layer, and the first covering layer contains a fluorine-free compound and / or a fluorine-containing compound.

[0009] The present application uses the compound with single-sided rotation characteristics shown in Formula I as the light-emitting layer material, and with the double-layer covering layer structure, it can significantly improve the efficiency and life of the organic electroluminescent device, while maintaining a low operating voltage. Device testing has shown that the device efficiency can be improved by more than 16%, and the device life can be improved by 400%. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The following drawings describe in detail the exemplary embodiments disclosed in this application. The same reference numerals represent similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting, exemplary embodiments, and the drawings are only used for the purpose of illustration and description, and are not intended to limit the scope of this application. Other embodiments may also accomplish the inventive intent in this application. It should be understood that the drawings are not drawn to scale. Among them:

[0011] Figure 1 This is a schematic diagram of the structure of the organic electroluminescent device of Example 1 of the present application. DETAILED DESCRIPTION

[0012] The following description provides specific application scenarios and requirements of the present application, with the purpose of enabling those skilled in the art to make and use the content in the present application. It will be apparent to those skilled in the art that various local modifications to the disclosed embodiments are apparent, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present application. Therefore, the present application is not limited to the embodiments shown, but to the widest scope consistent with the claims.

[0013] Explanation of related terms:

[0014] Substituted or unsubstituted: refers to being substituted by one or more substituents, or not substituted, and the substituents when substituted can be selected from the following: deuterium, halogen group, fluorine atom, trifluoromethyl, cyano, nitro, hydroxyl, carbonyl, ester group, imide group, amino, phosphorus oxygen group, alkoxy group, aryloxy group, sulfone group, sulfoxide group, alkylthio group, arylthio group, alkylsulfonyl group, arylsulfonyl group, silyl group, boron group, alkyl group, cycloalkyl group, alkenyl group, aryl group, heteroaryl group, aralkyl group, aralkenyl group, alkylaryl group, alkylamino group, aralkylamino group, heteroarylamino group, arylamino group, arylphosphino group, heterocyclic group, carboxyl derivative group; or substituted by a substituent connecting two or more substituents in the above-exemplified substituents. For example, "a substituent connecting two or more substituents" can include a biphenyl group, that is, the biphenyl group can be an aryl group, or a substituent connecting two phenyl groups. When substituted by two or more substituents, adjacent substituents can also be bonded to form a ring. As an example, bonding to form a ring can be achieved by chemical bonding, or by fusion.

[0015] Aryl: not particularly limited, and may be a monocyclic aromatic group or a polycyclic aromatic group. In some embodiments, monocyclic aromatic groups include, but are not limited to, phenyl, biphenyl, terphenyl, quaterphenyl, pentaphenyl, and the like. Polycyclic aromatic groups include, but are not limited to, naphthyl, anthracenyl, phenanthrenyl, pyrenyl, peryl, fluorenyl, and the like. Fluorenyl may be substituted, such as 9,9'-dimethylfluorenyl, 9,9'-dibenzofluorenyl, and the like. In addition, two of the substituents may be combined with each other to form a spiro ring structure, such as 9,9'-spirobifluorenyl, and the like.

[0016] The above description of the aryl group may be applied to the aryl group in the aryloxy group, arylthio group, arylsulfonyl group, arylphosphino group, arylalkyl group, arylalkylamino group, arylalkenyl group, alkylaryl group, arylamino group and arylheteroarylamino group.

[0017] Heteroaryl: contains one or more of B, N, O, P, S, Si and Se as heteroatoms. Heteroaryl includes, but is not limited to, pyridyl, pyrrolyl, pyrimidinyl, pyridazinyl, furanyl, thienyl, imidazolyl, pyrazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, triazolyl, oxadiazolyl, thiadiazolyl, dithiazolyl, tetrazolyl, pyranyl, thiopyranyl, pyrazinyl, azinyl, thiazinyl, dioxinyl, triazinyl, tetrazinyl, quinolyl, isoquinolyl, quinolyl, quinazolinyl, quinoxalinyl, naphthyridinyl, acridinyl, xanthenyl, phenanthridinyl, naphthyridinyl, triazaindenyl, indolyl, dihydroindole, indolizinyl, phthalazinyl, pyridopyrimidinyl, pyridopyrazinyl, pyrazinopy ... Pyrazinyl, benzothiazolyl, benzoxazolyl, benzimidazolyl, benzothiophenyl, benzofuranyl, dibenzothiophenyl, dibenzofuranyl, carbazolyl, benzocarbazolyl, dibenzocarbazolyl, indolecarbazolyl, indenocarbazolyl, phenazine, imidazopyridyl, phenazine, phenanthridinyl, phenanthrolinyl, phenothiazine, imidazopyridyl, imidazophenanthridinyl, benzimidazoquinazolinyl, benzimidazophenanthridinyl, spiro[fluorene-9,9'-xanthene], benzobinaphthyl, dinaphthofuranyl, naphthylbenzofuranyl, dinaphthothienyl, naphthylbenzothienyl, triphenylphosphine oxide, triphenylborane, etc.

[0018] The above description of the heteroaryl group may be applied to the heteroaryl group in the heteroarylamine group and the arylheteroarylamine group.

[0019] Alkyl: may be linear or branched, including but not limited to methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methyl-butyl, 1-ethyl-butyl, pentyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl, n-heptyl, 1-methylhexyl, cyclopentylmethyl, cyclohexylmethyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 1-ethyl-propyl, 1,1-dimethyl-propyl, isohexyl, 4-methylhexyl, 5-methylhexyl.

[0020] The above description of the alkyl group also applies to the alkyl group in the aralkyl group, aralkylamino group, alkylaryl group and alkylamino group.

[0021] Heteroalkyl: can be a straight or branched alkyl containing heteroatoms, and the number of carbon atoms is not particularly limited. In some embodiments, heteroalkyl includes but is not limited to alkoxy, alkylthio, alkylsulfonyl, etc. Alkoxy, for example, can include methoxy, ethoxy, n-propoxy, isopropoxy, isopropoxy (isopropoxy), i-propyloxy, n-butoxy, isobutoxy, tert-butoxy, sec-butoxy, n-pentoxy, neopentoxy, isopentyl, n-hexyl, 3,3-dimethylbutoxy, 2-ethylbutoxy, n-octyloxy, n-nonyloxy, n-decyloxy, benzyloxy, p-methylbenzyloxy, etc. The alkylthio group may include, for example, methylthio, ethylthio, n-propylthio, isopropylthio, isopropylthio, n-butylthio, isobutylthio, tert-butylthio, sec-butylthio, n-pentylthio, neopentylthio, isopentylthio, n-hexylthio, 3,3-dimethylbutylthio, 2-ethylbutylthio, n-octylthio, n-nonylthio, n-decylthio, benzylthio and the like.

[0022] Cycloalkyl: a cyclic saturated hydrocarbon group, such as cyclopropyl, cyclobutyl, cyclopentyl, 3-methylcyclopentyl, 2,3-dimethylcyclopentyl, cyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl, 2,3-dimethylcyclohexyl, 3,4,5-trimethylcyclohexyl, 4-tert-butylcyclohexyl, cycloheptyl, cyclooctyl, etc.

[0023] Heterocycloalkyl: a cycloalkyl group containing heteroatoms, for example: wait.

[0024] The above is a detailed description of some terms appearing in the present application. Next, the technical solution of the present application will be described in detail.

[0025] Anthracene is the most commonly used blue fluorescent host material, and its 9th and 10th positions are very active, so the 9th and 10th positions need to be substituted. Among them, the most stable ones are aryl substitutions, such as phenyl, naphthyl, phenanthrenyl, pyrenyl, etc., or aromatic groups formed by their combination, such as biphenyl, phenyl-binaphthyl, terphenyl, quaterphenyl, etc. Since phenyl, naphthyl, phenanthrenyl, pyrenyl and other aromatic groups and aromatic groups formed by their combination can be bonded to anthracene at different positions when replacing anthracene, thousands of compounds can be formed, and which compounds can improve device performance is worth studying. However, it is not easy to screen out compounds that can improve device performance from thousands of compounds.

[0026] In this regard, the inventors of this application have conducted in-depth research on the performance of the device. The luminous efficiency of the device is mainly composed of two parts. The first part is the efficiency of the singlet energy of the luminescent host material being transferred to the luminescent guest material to form fluorescence; the second part is the efficiency of the triplet excitons of the luminescent host material being stacked and collided to form singlet delayed fluorescence. When the fluorescence of any part is insufficient, the luminous efficiency will be reduced. The process of transferring the singlet energy of the luminescent host material to the luminescent guest material is affected by the intensity of molecular vibration. The lower the molecular vibration intensity, the more sufficient the singlet energy transfer, making the efficiency of the first part higher. The collision process of triplet excitons is affected by the exciton concentration and the exciton distance. The smaller the exciton distance and the greater the exciton concentration, the higher the collision efficiency, making the efficiency of the second part higher.

[0027] Furthermore, the vibration intensity of a molecule is related to the rotational characteristics of the molecule. Compared with molecules that cannot rotate freely, molecules that can rotate freely have more molecular conformations at room temperature and pressure, so the vibration intensity is greater. If a molecule that can rotate freely is used as a luminescent host material, it will cause the singlet energy to be transferred to the luminescent guest material, and some of the vibration energy transfer is insufficient, which leads to a low luminous efficiency. Therefore, if a substituent that can rotate freely is introduced at the 9th and 10th positions of anthracene, the molecular rotational vibration will be strengthened, thereby making the singlet energy transfer efficiency low. For example, when biphenyl, terphenyl, biphenylnaphthalene, biphenylphenanthrene, etc. or their combined structures are introduced at the 9th and 10th positions of anthracene, the singlet energy transfer efficiency will be reduced. In order to reduce rotational vibration, steric substituents can be introduced at the 9th and 10th positions of anthracene to limit rotation, thereby improving the luminous efficiency. However, if steric substituents are introduced at both the 9th and 10th positions of anthracene, isomers will be produced, and the ratio of the isomers will be difficult to control. At the same time, the large steric hindrance of the substituents will also cause more molecules to be distributed in a conformation perpendicular to the anthracene and the substituents, thereby reducing the stability of anthracene and affecting the device life.

[0028] Finally, the inventors of the present application proposed a method of selecting a site at the 9th and 10th positions of anthracene to restrict rotation, while the other site does not restrict rotation, that is, the substituent at one of the 9th and 10th positions of anthracene cannot rotate freely, while the substituent at the other site can rotate freely, which can both improve the efficiency of singlet energy transfer and ensure the stability of anthracene. It should be noted that in the present application, the substituent can rotate freely means that the substituent can undergo a dihedral angle change of greater than 180 degrees relative to the anthracene group under normal temperature and pressure conditions. Similarly, the substituent cannot rotate freely means that the substituent cannot undergo a dihedral angle change of greater than 180 degrees relative to the anthracene group under normal temperature and pressure conditions. The dihedral angle change can refer to the rotational enantiomerism phenomenon (according to Lexikon Chemie Lexicon of Chemistry Definition - Version 2.0, Stuttgart / New York: Georg Thieme Verlag 1999]).

[0029] Among the many substituents, the electrons of the phenanthryl group have large π conjugation and smaller vibration than phenyl and naphthyl groups, and the singlet energy transfer efficiency is higher. At the same time, as a large planar substituent, the phenanthryl group can make the molecules more compact through π-π stacking, and the triplet collision efficiency of the molecules is higher. Therefore, the phenanthryl group can be used as a substituent at the 9th or 10th position of anthracene, while the phenyl or naphthyl group can be used as a substituent at another position. At the same time, in order to further improve the device life, anthracene and its substituents can be deuterated.

[0030] Based on this, the present application provides an organic electroluminescent device, comprising: a first electrode, a second electrode, an organic layer and a covering layer structure. The organic layer is located between the first electrode and the second electrode, and the organic layer includes a light-emitting layer, and the light-emitting layer includes a compound represented by the following formula I:

[0031] In Formula I, the substituent Ar1 is a substituent bonded to the 9-position of the anthracene group, and is selected from an undeuterated phenanthracene group, a partially or fully deuterated phenanthracene group. The substituent Ar2 is a substituent bonded to the 10-position of the anthracene group, and is selected from a partially or fully deuterated phenyl group, a partially or fully deuterated naphthyl group. In particular, among the substituent Ar1 and the substituent Ar2, only one substituent can have a dihedral angle change of greater than 180 degrees relative to the anthracene group at room temperature and pressure, that is, only one substituent among the substituent Ar1 and the substituent Ar2 can rotate freely relative to the anthracene group. That is, one of the substituents in the substituent Ar1 and the substituent Ar2 can rotate freely relative to the anthracene group, while the other substituent cannot rotate freely relative to the anthracene group. In other words, the compound shown in Formula I contained in the light-emitting layer of the present application has a single-sided rotation characteristic.

[0032] Whether the substituents at positions 9 and 10 of anthracene can rotate freely depends on the steric hindrance of the substituent and anthracene. When the steric hindrance between anthracene and the substituent is small, the substituent can rotate freely, and when the steric hindrance between anthracene and the substituent is large, the substituent cannot rotate freely. Therefore, when the phenanthryl group is used as a substituent, the steric hindrance between the phenanthryl group and anthracene is different when it is connected to the 9 position of anthracene at different positions, so that the rotation characteristics of the phenanthryl group also change accordingly, and then the requirements for the rotation characteristics of the substituent at position 10 will also change. Specifically, when the phenanthryl group at position 9 can rotate freely, the substituent at position 10 is required not to rotate freely; when the phenanthryl group at position 9 cannot rotate freely, the substituent at position 10 is required to rotate freely.

[0033] In some preferred embodiments, the compound represented by formula I is selected from the following group:

[0034]

[0035] In the above formula, D(m) represents that the phenanthryl group is substituted by m deuterium groups, and m≤9.

[0036] The substituent rotation characteristics of the above compounds BH1 to BH7 are as follows:

[0037]

[0038] in Representatives can spin freely. Therefore, compounds BH1 to BH7 all meet the requirements of the present application for unilateral rotation characteristics.

[0039] Further preferably, m is 9, and the compound represented by formula I is selected from the following group:

[0040]

[0041] In some preferred embodiments, the luminescent layer includes a luminescent host material and a luminescent guest material, wherein the luminescent host material includes the compound shown in the formula I, and the luminescent guest material may include a nitrogen-boron resonance material. The luminescent spectrum of the nitrogen-boron resonance material is a narrow spectrum. Although the luminescent efficiency can be further improved, higher requirements are also put forward for the luminescent host material matched therewith. Due to the large conjugated area of ​​the nitrogen-boron resonance material, it is easy to interact with the luminescent host material by π-π, so that the luminescent guest material is affected by the luminescent host material, resulting in low photoluminescence efficiency. To solve this problem, on the one hand, more alkyl groups can be introduced into the nitrogen-boron resonance material molecule to alleviate this type of effect, and on the other hand, this effect can be reduced by selecting a suitable luminescent host material. The luminescent host material of the present application uses the compound shown in formula I with a single-sided rotation characteristic. Under the action of rotation restriction, the anthracene group in the compound shown in formula I is not easy to interact with the nitrogen-boron resonance material. Therefore, the luminescent host material of the present application is a good choice for nitrogen-boron resonance materials. When the compound shown in formula I is matched with the nitrogen-boron resonance material as the luminescent layer material, the luminescent efficiency of the device can be further improved.

[0042] In some preferred embodiments, the luminescent guest material comprises a compound represented by the following formula II or III:

[0043]

[0044] wherein Q1 and Q2 are each independently selected from substituted or unsubstituted phenyl, substituted or unsubstituted benzofuranyl, substituted or unsubstituted benzothiophenyl, substituted or unsubstituted benzocycloalkyl, and the substituent when substituted is selected from deuterium, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, alkyl or cycloalkyl having 1 to 10 carbon atoms; n is selected from 0, 1, 2, 3; when R is present, it is selected from deuterium, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, alkyl or cycloalkyl having 1 to 10 carbon atoms; wherein n is 3 and R is selected from an alkyl group or a cycloalkyl group having 1 to 10 carbon atoms, two adjacent Rs form a ring; Ar1 ​​and Ar2 are each independently selected from a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms, or a substituted or unsubstituted aryl-cycloalkyl group having 6 to 30 carbon atoms, and the substituent when substituted is selected from an aryl group having 6 to 30 carbon atoms, a heteroaryl group having 3 to 30 carbon atoms, or an alkyl group or a cycloalkyl group having 1 to 10 carbon atoms.

[0045] Preferably, the luminescent guest material is selected from the following group:

[0046]

[0047]

[0048] In some preferred embodiments, in the light-emitting layer, the mass percentage of the compound represented by formula I is 95% to 99%, and the mass percentage of the light-emitting guest material is 1% to 5%.

[0049] In order to maximize the luminous efficiency of the device, the present application adopts a double-layer covering layer structure. The covering layer structure includes a first covering layer located on the second electrode and a second covering layer located on the first covering layer, wherein the refractive index of the first covering layer is lower than the refractive index of the second covering layer. The use of a low-refractive-index covering layer combined with a high-refractive-index covering layer can better transmit light out of the device, thereby improving the luminous efficiency of the device.

[0050] In some preferred embodiments, the difference in refractive index between the first covering layer and the second covering layer for light of 460 nm wavelength is greater than 0.4; more preferably, the difference is greater than 0.56; further preferably, the difference is greater than 0.6; even more preferably, the difference is greater than 0.7.

[0051] In some preferred embodiments, the refractive index of the first covering layer for light with a wavelength of 460 nm is lower than 1.7; more preferably, lower than 1.6; further preferably, lower than 1.5.

[0052] In some preferred embodiments, the refractive index of the second covering layer for light with a wavelength of 460 nm is greater than 1.9; more preferably, greater than 2.0; further preferably, greater than 2.1; and even more preferably, greater than 2.2.

[0053] In some preferred embodiments, the absorption rate of the second covering layer to light with a wavelength of 460 nm is less than 0.01%.

[0054] The lower the refractive index of the first covering layer, the more conducive it is to improve the efficiency of the device. In order to reduce the refractive index of the first covering layer as much as possible, it is necessary to isolate the material molecules of the first covering layer and blue-shift the spectrum, and the most effective method is to introduce fluorine atoms for molecular isolation. Furthermore, since fluorine atoms may repel the metal cathode, peeling between the first covering layer and the metal cathode may occur, which may lead to the problem of reduced device efficiency and life. To solve this problem, the present application introduces at least one heteroatom selected from nitrogen atoms, oxygen atoms, sulfur atoms, and phosphorus atoms into the material molecules of the first covering layer. These heteroatoms can attract the metal cathode, thereby weakening the repulsive force between fluorine atoms and the metal electrode, thereby achieving the effect of reducing the refractive index while maintaining the efficiency and life of the device. Of course, the material of the first covering layer is preferably a fluorine-free compound to avoid the peeling problem between the covering layer and the metal cathode.

[0055] In order to further enable high-efficiency devices to maintain stable efficiency in foldable or high-temperature environments, through a large number of experiments and calculations, it was found that if the first covering layer contains a fluorine-containing compound, in the fluorine-containing compound, when the mass proportion of fluorine atoms does not exceed 30%, and the total mass proportion of nitrogen atoms, oxygen atoms, sulfur atoms and phosphorus atoms is not less than 10%, the effect is better. More preferably, the mass proportion of fluorine atoms does not exceed 20%, and the total mass proportion of nitrogen atoms, oxygen atoms, sulfur atoms and phosphorus atoms is not less than 20%; more preferably, the mass proportion of fluorine atoms does not exceed 10%, and the total mass proportion of nitrogen atoms, oxygen atoms, sulfur atoms and phosphorus atoms is not less than 30%.

[0056] In some preferred embodiments, the material of the first covering layer is selected from the following group:

[0057]

[0058]

[0059] In some preferred embodiments, the material of the second covering layer is selected from the following group:

[0060]

[0061]

[0062] In order to make the organic electroluminescent device more efficient, the organic layer further includes a hole injection layer located between the first electrode and the light-emitting layer. The thickness of the hole injection layer can be 100 angstroms to 300 angstroms. Preferably, the hole injection layer includes a hole injection host material and a hole dopant, wherein the mass proportion of the hole dopant can be 1% to 5%. The hole injection host material is selected from the following group:

[0063]

[0064] Wherein: L1 to L4, when present, are independently selected from a single bond or a phenylene group; Ar3 to Ar 12 When each exists, it is independently selected from substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl groups having 3 to 30 carbon atoms, and when substituted, the substituent is selected from alkyl groups having 1 to 10 carbon atoms; preferably, Ar3 to Ar4 12 When each exists, it is independently selected from phenyl, biphenyl, dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazolyl, benzo[B]naphtho[2,3-D]furan, benzo[B]naphtho[1,2-D]furan, benzo[B]naphtho[2,1-D]furan; when R1 and R2 exist, they are independently selected from substituted or unsubstituted alkyl having 1 to 10 carbon atoms, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, and the substituent when substituted is selected from alkyl having 1 to 10 carbon atoms, or R1 and R2 are bonded to form a ring.

[0065] In some preferred embodiments, the hole dopant is selected from the following compounds:

[0066] Among them, R3~R 19 Each is independently selected from fluorine, trifluoromethyl, cyano, and nitro.

[0067] In some preferred embodiments, the organic layer further comprises a first hole transport layer located between the hole injection layer and the light emitting layer, and the material selection range of the first hole transport layer is the same as that of the hole injection host material.

[0068] In some preferred embodiments, the material of the first hole transport layer is selected from the following group:

[0069]

[0070]

[0071] The thickness of the first hole transport layer may be 3nm to 150nm. When there is no second hole transport layer, the thickness of the first hole transport layer is 40nm to 150nm; when there is a second hole transport layer, the thickness of the first hole transport layer is 3nm to 40nm.

[0072] In some preferred embodiments, the organic layer further comprises a second hole transport layer between the first hole transport layer and the light emitting layer, and the thickness of the second hole transport layer may be 5nm to 150nm. The material of the second hole transport layer is selected from the following group:

[0073]

[0074]

[0075] Among them, R 20 , R 21 and R 22 When each is present, it is independently selected from hydrogen, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and a substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms.

[0076] In some preferred embodiments, the material of the second hole transport layer is selected from the following compounds:

[0077]

[0078]

[0079] In some preferred embodiments, the organic layer further comprises an electron transport layer located between the light-emitting layer and the second electrode, and the electron transport layer may be a single layer or a multilayer. As an example, the electron transport layer may include a first electron transport layer and / or a second electron transport layer.

[0080] The thickness of the first electron transport layer can be 3nm to 40nm, 3nm to 10nm, 10nm to 20nm, 20nm to 30nm, 30nm to 40nm, 20nm to 40nm, etc. The first electron transport layer can be a single compound or mixed with other metal compounds, such as 8-hydroxyquinoline lithium. In some embodiments, the material of the first electron transport layer is selected from s-triazine compounds. In some preferred embodiments, the material of the first electron transport layer is selected from the following compounds:

[0081] L 1-1 is selected from a single bond, phenyl, biphenyl, naphthyl; R 1-1 Selected from hydrogen, phenyl, biphenyl; Ar 1-1 ~Ar 3-1Independently selected from hydrogen, phenyl, 9,9'-dimethylfluorenyl, 9,9'-diphenylfluorenyl, 9,9'-spirofluorenyl, 9,9'-xanthenespirofluorenyl, and phenanthryl.

[0082] Preferably, the material of the first electron transport layer is selected from the following group:

[0083]

[0084]

[0085] The thickness of the second electron transport layer may be 10 nm to 40 nm. The material of the second electron transport layer is selected from the following group:

[0086]

[0087] Wherein, L5 to L8, when present, are independently selected from a single bond, phenyl, biphenyl, naphthyl, 9,9'-dimethylfluorenyl, 9,9'-spirobifluorenyl; Ar 13 ~Ar 16 When each exists, it is independently selected from a substituted or unsubstituted C6-C50 aryl group, a substituted or unsubstituted C3-C50 heteroaryl group, and a substituted or unsubstituted phosphonyl group.

[0088] Preferably, the material of the second electron transport layer is selected from the following group:

[0089]

[0090]

[0091] In some preferred embodiments, the second electron transport layer further comprises 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 detailed examples include metal lithium compounds, metal calcium compounds, metal magnesium compounds, metal samarium compounds, metal ytterbium compounds, etc. More specific examples include 8-hydroxyquinoline lithium, lithium fluoride, magnesium fluoride, ytterbium fluoride, calcium fluoride, etc. When the second electron transport material is mixed with the metal compound, the mass proportion of the second electron transport material can be 20% to 80%, 20% to 40%, 40% to 60%, 60% to 80%, etc. When the second electron transport material is mixed with a metal, for example, with an alkali metal, an alkaline earth metal, a rare earth metal, and more specifically with lithium metal, magnesium metal, calcium metal, ytterbium metal, samarium metal, and the like, when mixed with a metal, the mass proportion 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%, and the like.

[0092] In some preferred embodiments, the organic layer further comprises an electron blocking layer, which can have both hole transport function and electron blocking function. At the same time, the higher triplet excitation energy level of the electron blocking layer can block the excitons generated in the light-emitting layer in the light-emitting layer, thereby improving the luminous efficiency of the device. The electron blocking layer can be formed of conventional materials.

[0093] In some preferred embodiments, in order to enhance the balance of hole and electron concentrations, a hole blocking layer is inserted between the light-emitting layer and the electron transport layer to balance the carrier concentration and prevent exciton quenching. The hole blocking layer material can be a conventional material with strong stability, good film forming properties and a sufficiently high highest molecular occupied orbital.

[0094] In some preferred embodiments, the organic layer further comprises an electron injection layer, and the electron injection layer is located between the electron transport layer and the second electrode. The material of the electron injection layer can be selected from alkali metals, alkaline earth metals, rare earth metals or inorganic substances or coordination compounds thereof.

[0095] In some embodiments, the first electrode is an anode and the second electrode is a cathode. Usually, the anode has requirements such as good conductivity, flat surface, and not prone to cracks. At the same time, there are certain requirements for the work function, mainly to be able to match the hole injection layer and exert the hole injection effect. When the top emission method (cathode side light emission) is adopted, the anode adopts a metal compound with a work function of 4.2eV or more, for example, indium tin oxide alloy, tin oxide, indium zinc oxide, gold, silver, platinum, copper, carbon nanotubes, carbon nanowires, graphene, etc. The thickness is 10nm to 200nm, preferably 10nm to 50nm. A reflective electrode is set under the anode (close to the substrate end). The reflective electrode is generally made of metal or metal alloy, for example, silver metal, copper metal, aluminum metal, gold metal or alloys of these metals and other metals. The reflectivity of the reflective electrode is relatively high, and the reflectivity is required to be more than 90%. The thickness is usually used at a thickness of 100nm to 500nm, preferably in the range of 80nm to 150nm. When the bottom emission method (light emitting from the substrate side) is adopted, the anode adopts a metal compound with a work function of 4.2eV or more, for example, indium tin oxide alloy, tin oxide, indium zinc oxide, gold, silver, platinum, copper, carbon nanotubes, carbon nanowires, graphene, etc. The thickness is 10nm to 1μm, preferably 50nm to 200nm. The anode can be made by forming a thin film of the electrode material by evaporation, sputtering, coating, etc.

[0096] The cathode requires a material with good electrical conductivity and good surface flatness. In order to improve the electron injection capability, a material with a small work function is usually selected. The cathode material can be a single-layer cathode, or a double-layer or multi-layer cathode, generally a metal or a metal alloy. For a single-layer cathode, silver, copper, aluminum, gold, or alloys of these metals with other metals, such as alloys with rare earth metals, alkali metals, and alkaline earth metals, can be used, which can be listed as magnesium-indium alloy, magnesium-aluminum alloy, aluminum-potassium alloy, aluminum-scandium-potassium alloy, magnesium-silver alloy, silver-ytterbium alloy, silver-samarium alloy, etc. If the cathode uses a double-layer metal, the cathode near the light-emitting layer can use alkali metals, alkaline earth metals, rare earth metals, etc., such as lithium, calcium, magnesium, ytterbium, etc., to increase the electron injection ability. The cathode layer far from the light-emitting side is mainly used to improve the conductivity. Generally, silver, copper, aluminum, gold or alloys of these metals and other metals can be used, such as alloys with rare earth metals, alkali metals, and alkaline earth metals, which can be listed as 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, etc. When light comes out from the anode side, the cathode is required to be non-transparent, and a cathode larger than 100nm can be evaporated. When light comes out from the cathode side, the cathode is required to be transparent, and the transmittance at this time should be greater than 40%, and the thickness is 10nm to 20nm.

[0097] In addition, the organic electroluminescent device may further include a substrate, which is generally located below the anode and may be made of plastic or glass, and may be rigid or bendable. The substrate may have a driving unit that can drive the corresponding pixel to emit light.

[0098] As an example, the structure of the organic electroluminescent device of the present application can be selected from one of the following:

[0099] (1) An organic electroluminescent device includes an anode, a hole injection layer, a first hole transport layer, a light-emitting layer, a first electron transport layer, and a cathode stacked in sequence, that is, anode / hole injection layer / first hole transport layer / light-emitting layer / first electron transport layer / cathode / first covering layer / second covering layer. Each device structure will be expressed in this simplified manner below.

[0100] (2) anode / hole injection layer / second hole transport layer / first hole transport layer / light-emitting layer / first electron transport layer / cathode / first covering layer / second covering layer.

[0101] (3) anode / hole injection layer / second hole transport layer / first hole transport layer / light-emitting layer / first electron transport layer / second electron transport layer / cathode / first covering layer / second covering layer.

[0102] (4) anode / hole injection layer / second hole transport layer / first hole transport layer / light-emitting layer / first electron transport layer / second electron transport layer / electron injection layer / cathode / first covering layer / second covering layer.

[0103] (5) anode / hole injection layer / second hole transport layer / first hole transport layer / light-emitting layer / first electron transport layer / second electron transport layer / multilayer cathode / first covering layer / second covering layer.

[0104] (6) anode / hole injection layer / first hole transport layer / first light-emitting layer / carrier generation layer / first hole transport layer / second light-emitting layer / first electron transport layer / cathode / first covering layer / second covering layer.

[0105] (7) anode / hole injection layer / first hole transport layer / first light-emitting layer / carrier generation layer / first hole transport layer / second light-emitting layer / first electron transport layer / second electron transport layer / cathode / first covering layer / second covering layer.

[0106] (8) anode / hole injection layer / second hole transport layer / first hole transport layer / first light-emitting layer / carrier generation layer / first hole transport layer / second light-emitting layer / first electron transport layer / cathode / first covering layer / second covering layer.

[0107] (9) anode / hole injection layer / second hole transport layer / first hole transport layer / first light-emitting layer / carrier generation layer / first hole transport layer / second light-emitting layer / first electron transport layer / second electron transport layer / cathode / first covering layer / second covering layer.

[0108] (10) anode / hole injection layer / hole transport layer / electron blocking layer / light-emitting layer / electron transport layer / electron injection layer / cathode / first covering layer / second covering layer.

[0109] (11) anode / hole injection layer / first hole transport layer / second hole transport layer / light-emitting layer / hole blocking layer / electron transport layer / cathode / first covering layer / second covering layer.

[0110] (12) anode / hole injection layer / first hole transport layer / second hole transport layer / light-emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode / first covering layer / second covering layer.

[0111] (13) anode / hole injection layer / hole transport layer / electron blocking layer / light-emitting layer / hole blocking layer / electron transport layer / cathode / first covering layer / second covering layer.

[0112] (14) anode / hole injection layer / hole transport layer / light-emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode / first covering layer / second covering layer.

[0113] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solution of the present application. Unless otherwise specified, the reagents and raw materials used can be purchased through commercial channels. The experimental methods in the following examples that do not specify specific conditions are usually measured according to national standards. If there is no corresponding national standard, then according to general international standards, conventional methods and conditions, or according to the conditions recommended by the manufacturer, or selected according to the product specifications.

[0114] Example 1

[0115] refer to Figure 1 This embodiment provides an organic electroluminescent device, and its preparation method includes the following steps:

[0116] (1) A transparent ITO film layer (thickness 150 nm) is formed on a glass substrate 1 by magnetron sputtering to obtain a reflective anode 10 .

[0117] (2) A mixed material of Compound 1 and Compound 2 in a mass ratio of 1:99 was deposited on the surface of the reflective anode 10 to form a hole injection layer 20 with a thickness of 10 nm.

[0118] (3) Compound 2 was evaporated on the surface of the hole injection layer 20 to form a first hole transport layer 31 with a thickness of 100 nm.

[0119] (4) Compound 3 is evaporated on the surface of the first hole transport layer 31 to form a second hole transport layer 32 with a thickness of 5 nm.

[0120] (5) The light-emitting host material compound 4 and the light-emitting guest material compound 5 were co-evaporated at a mass ratio of 99:1 to form a light-emitting layer 40 with a thickness of 25 nm.

[0121] (6) Compound 6 was evaporated on the surface of the light-emitting layer 40 to form a hole blocking layer 50 with a thickness of 5 nm.

[0122] (7) Compound 7 and LiQ were deposited on the surface of the hole blocking layer 50 at a mass ratio of 2:3 to form an electron transport layer 60 with a thickness of 30 nm.

[0123] (8) Metal ytterbium (Yb) is deposited on the surface of the electron transport layer 60 to a thickness of 5 nm to form the electron injection layer 70 .

[0124] (9) Magnesium (Mg) and silver (Ag) are mixed and deposited on the surface of the electron injection layer 70 at an evaporation rate of 1:9 to form a second electrode with a thickness of 14 nm as the cathode 80.

[0125] (10) A low-refractive index material compound 9 is first evaporated on the surface of the cathode 80 to form a first covering layer 91 with a thickness of 20 nm. Then, a high-refractive index material compound 8 is evaporated on the surface of the first covering layer 91 to form a second covering layer 92 with a thickness of 60 nm.

[0126] The structural formulas of the compounds involved in the above preparation process are shown in Table 1.

[0127] Table 1 Compound structure

[0128]

[0129]

[0130] Example 2

[0131] Compared with Example 1, the difference of the method for preparing the organic electroluminescent device of this embodiment is that when forming the light-emitting layer 40, the following compound is used to replace the light-emitting host material compound 4:

[0132]

[0133] Example 3

[0134] Compared with Example 1, the difference of the method for preparing the organic electroluminescent device of this embodiment is that when forming the light-emitting layer 40, the following compound is used to replace the light-emitting host material compound 4:

[0135]

[0136] Example 4

[0137] Compared with Example 1, the difference of the method for preparing the organic electroluminescent device of this embodiment is that when forming the light-emitting layer 40, the following compound is used to replace the light-emitting host material compound 4:

[0138]

[0139] Example 5

[0140] Compared with Example 1, the difference of the method for preparing the organic electroluminescent device of this embodiment is that when forming the light-emitting layer 40, the following compound is used to replace the light-emitting host material compound 4:

[0141]

[0142] Example 6

[0143] Compared with Example 1, the difference of the method for preparing the organic electroluminescent device of this embodiment is that when forming the light-emitting layer 40, the following compound is used to replace the light-emitting host material compound 4:

[0144]

[0145] Example 7

[0146] Compared with Example 1, the difference of the method for preparing the organic electroluminescent device of this embodiment is that when forming the light-emitting layer 40, the following compound is used to replace the light-emitting host material compound 4:

[0147]

[0148] Example 8

[0149] Compared with Example 1, the difference in the preparation method of the organic electroluminescent device of this comparative example is that when forming the first covering layer 91, the following compound is used instead of compound 9:

[0150]

[0151] Comparative Example 1

[0152] Compared with Example 1, the difference in the preparation method of the organic electroluminescent device of this comparative example is that when forming the light-emitting layer 40, the following compound is used to replace the light-emitting host material compound 4:

[0153] The substituents at positions 9 and 10 of this compound are not able to rotate freely.

[0154] Comparative Example 2

[0155] Compared with Example 1, the difference in the preparation method of the organic electroluminescent device of this comparative example is that when forming the light-emitting layer 40, the following compound is used to replace the light-emitting host material compound 4:

[0156] The substituents at positions 9 and 10 of this compound can rotate freely.

[0157] Comparative Example 3

[0158] Compared with Example 1, the difference in the preparation method of the organic electroluminescent device of this comparative example is that when forming the light-emitting layer 40, the following compound is used to replace the light-emitting host material compound 4:

[0159]

[0160] Comparative Example 4

[0161] Compared with Example 1, the only difference in the method for preparing the organic electroluminescent device of this comparative example is that the step of forming the first covering layer 91 is omitted.

[0162] Device performance test

[0163] The FSTAR lifetime measurement system equipped with a power supply and a photodiode as the detection unit was used to test the LT95 lifetime of the device under dark conditions (the test current was 10 mA / cm 2 ), LT95 life refers to the time (hours) required for the brightness to decay from the initial brightness to 95%. The computer-controlled Keithley 2400 test system was used to test the operating voltage and efficiency of the device (test current was 10mA / cm 2 ), the efficiency uses BI efficiency as the evaluation index, and BI efficiency is equal to the current efficiency (Cd / A) divided by the value of CIEy, that is, BI efficiency is Cd / A / CIEy. Table 2 shows the test results of the device performance.

[0164] Table 2 Device performance test results

[0165]

[0166] It can be seen from Table 2 that the organic electroluminescent device of the embodiment of the present application has both high efficiency and life span, while maintaining a low operating voltage.

[0167] According to the comparison results of Example 1 and Comparative Example 1, when the light-emitting main material is replaced by the compound with non-rotatable double-sided structure of Comparative Example 1 with the compound with single-sided rotation property of Example 1, the device efficiency and life are improved, among which the device life is improved by 69.1%, and the operating voltage is also reduced from 4.05 to 3.58.

[0168] According to the comparison results of Example 1 and Comparative Example 2, when the light-emitting main material is replaced by the compound that can rotate on both sides of Comparative Example 2 with the compound with single-sided rotation characteristics of Example 1, the device efficiency and life are significantly improved, among which the device efficiency is significantly improved by 16%, and the device life is significantly improved by 40.2%. Although the operating voltage of the device increases, the increase is small and still maintains a relatively low voltage level.

[0169] According to the comparison results of Example 1 and Comparative Example 3, when the light-emitting host material is replaced by the deuterated compound of Example 1 from the non-deuterated compound of Comparative Example 3, the device efficiency and operating voltage do not change much, but the device life is significantly improved by 79.6%.

[0170] According to the comparison results of Example 1 and Comparative Example 4, when the cover layer is replaced by the double-layer structure of Example 1 instead of the single-layer structure of Comparative Example 4, the device efficiency is increased by 11.7%, and the device life and operating voltage are also improved.

[0171] According to the comparison results of Example 1 and Example 8, when the fluorine-containing compound forming the first covering layer contains heteroatoms, compared with not containing heteroatoms, the device efficiency and life are improved, and the operating voltage is also reduced, and the life is significantly improved by 43.7%.

[0172] It can be seen that using the single-rotation compound of the present application as the light-emitting layer material and combining it with the double-layer covering layer structure of the present application can enable the organic electroluminescent device to have both higher efficiency and lifespan while maintaining a lower operating voltage.

[0173] The above description of the embodiments is to facilitate those of ordinary skill in the art to understand and apply the present application. It is obvious that those familiar with the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without having to pay creative labor. Therefore, the present application is not limited to the embodiments herein, and improvements and modifications made by those skilled in the art based on the contents disclosed in the present application without departing from the scope and spirit of the present application are within the scope of the present application.

Claims

1. An organic electroluminescent device, characterized in that: include: A first electrode, a second electrode, an organic layer, and a covering layer structure; The organic layer is located between the first electrode and the second electrode and includes a light-emitting layer, wherein the light-emitting layer includes a compound represented by the following formula I: Wherein, the substituent Ar1 bonded to the 9-position of the anthracene group is selected from an undeuterated phenanthryl group, a partially deuterated phenanthryl group or a fully deuterated phenanthryl group; the substituent Ar2 bonded to the 10-position of the anthracene group is selected from a partially deuterated phenyl group or a partially deuterated naphthalene group or a fully deuterated naphthalene group; and among the substituent Ar1 and the substituent Ar2, only one substituent can change the dihedral angle by more than 180 degrees relative to the anthracene group at room temperature and pressure; The covering layer structure includes a first covering layer located on the second electrode and a second covering layer located on the first covering layer, wherein the refractive index of the first covering layer is lower than that of the second covering layer, and the first covering layer contains a fluorine-free compound and / or a fluorine-containing compound.

2. The organic electroluminescent device according to claim 1, characterized in that: The compound represented by formula I is selected from the following group: Wherein, D(m) represents that the phenanthryl group is substituted by m deuterium groups, and m≤9.

3. The organic electroluminescent device according to claim 1 or 2, characterized in that: The light-emitting layer includes a light-emitting host material and a light-emitting guest material, wherein the light-emitting host material includes the compound shown in Formula I; and the light-emitting guest material includes the compound shown in Formula II or Formula III below: in: Q1 and Q2 are each independently selected from substituted or unsubstituted phenyl, substituted or unsubstituted benzofuranyl, substituted or unsubstituted benzothienyl, substituted or unsubstituted benzocycloalkyl, and the substituent when substituted is selected from deuterium, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, alkyl having 1 to 10 carbon atoms, or cycloalkyl; n is selected from 0, 1, 2, and 3; when R exists, it is selected from deuterium, substituted or unsubstituted aryl having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl having 3 to 30 carbon atoms, alkyl or cycloalkyl having 1 to 10 carbon atoms; when n is 3 and R is selected from alkyl or cycloalkyl having 1 to 10 carbon atoms, two adjacent Rs form a ring; Ar1 and Ar2 are each independently selected from a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, a substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms, or a substituted or unsubstituted aryl and cycloalkyl group having 6 to 30 carbon atoms, and the substituent when substituted is selected from an aryl group having 6 to 30 carbon atoms, a heteroaryl group having 3 to 30 carbon atoms, an alkyl group having 1 to 10 carbon atoms, or a cycloalkyl group.

4. The organic electroluminescent device according to claim 3, characterized in that: The luminescent guest material is selected from the following group:

5. The organic electroluminescent device according to claim 1, characterized in that: The fluorine-containing compound further comprises at least one heteroatom selected from the group consisting of a nitrogen atom, an oxygen atom, a sulfur atom and a phosphorus atom.

6. The organic electroluminescent device according to claim 5, characterized in that: In the fluorine-containing compound, the mass proportion of fluorine atoms does not exceed 30%, and the total mass proportion of nitrogen atoms, oxygen atoms, sulfur atoms and phosphorus atoms is not less than 10%.

7. The organic electroluminescent device according to claim 1, characterized in that: The difference in refractive index between the first cover layer and the second cover layer for light of 460 nm wavelength is greater than 0.

4.

8. The organic electroluminescent device according to claim 7, characterized in that: The refractive index of the first covering layer for light with a wavelength of 460 nm is lower than 1.7, and the refractive index of the second covering layer for light with a wavelength of 460 nm is greater than 1.

9.

9. The organic electroluminescent device according to any one of claims 5 to 8, characterized in that: The material of the first covering layer is selected from the following group:

10. The organic electroluminescent device according to claim 1, 7 or 8, characterized in that: The absorption rate of the second covering layer to light with a wavelength of 460 nm is less than 0.01%.

11. The organic electroluminescent device according to claim 10, characterized in that: The material of the second covering layer is selected from the following group:

12. The organic electroluminescent device according to claim 1, characterized in that: The organic layer further comprises a hole injection layer located between the first electrode and the light-emitting layer; the hole injection layer comprises a hole injection host material and a hole dopant, wherein the hole injection host material is selected from the following group: Wherein: L1 to L4, when present, are independently selected from a single bond or a phenylene group; Ar3~Ar 12 When each is present, it is independently selected from substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl groups having 3 to 30 carbon atoms, and when substituted, the substituent is selected from alkyl groups having 1 to 10 carbon atoms; Preferably, Ar3~Ar 12 When each is present, it is independently selected from phenyl, biphenyl, dimethylfluorenyl, dibenzofuranyl, dibenzothiophenyl, N-phenylcarbazolyl, benzo[B]naphtho[2,3-D]furan, benzo[B]naphtho[1,2-D]furan, benzo[B]naphtho[2,1-D]furan; When R1 and R2 exist separately, they are independently selected from substituted or unsubstituted alkyl groups having 1 to 10 carbon atoms, substituted or unsubstituted aryl groups having 6 to 30 carbon atoms, substituted or unsubstituted heteroaryl groups having 3 to 30 carbon atoms, and when substituted, the substituent is selected from alkyl groups having 1 to 10 carbon atoms, or R1 and R2 are bonded to form a ring.

13. The organic electroluminescent device according to claim 12, characterized in that: The hole dopant is selected from the following compounds: Among them, R3~R 19 Each is independently selected from fluorine, trifluoromethyl, cyano, and nitro.

14. The organic electroluminescent device according to claim 12, characterized in that: The organic layer further comprises a first hole transport layer located between the hole injection layer and the light emitting layer, and the material selection range of the first hole transport layer is the same as that of the hole injection host material.

15. The organic electroluminescent device according to claim 14, characterized in that: The material of the first hole transport layer is selected from the following group:

16. The organic electroluminescent device according to claim 14 or 15, characterized in that: The organic layer further includes a second hole transport layer located between the first hole transport layer and the light emitting layer, and the material of the second hole transport layer is selected from the following group: Among them, R 20 , R 21 and R 22 When each is present, it is independently selected from hydrogen, a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, and a substituted or unsubstituted heteroaryl group having 3 to 30 carbon atoms.

17. The organic electroluminescent device according to claim 16, characterized in that: The material of the second hole transport layer is selected from the following compounds:

18. The organic electroluminescent device according to claim 1, characterized in that: The organic layer further comprises an electron transport layer, which is located between the light-emitting layer and the second electrode, and a material of the electron transport layer is selected from the following group: Wherein, L5 to L8, when present, are independently selected from a single bond, phenyl, biphenyl, naphthyl, 9,9'-dimethylfluorenyl, 9,9'-spirobifluorenyl; Ar 13 ~Ar 16 When each exists, it is independently selected from a substituted or unsubstituted C6-C50 aryl group, a substituted or unsubstituted C3-C50 heteroaryl group, and a substituted or unsubstituted phosphonyl group.

19. The organic electroluminescent device according to claim 18, characterized in that: The material of the electron transport layer is selected from the following group:

20. The organic electroluminescent device according to claim 18 or 19, characterized in that: The organic electroluminescent device further comprises a hole blocking layer and / or an electron injection layer, wherein the hole blocking layer is located between the light-emitting layer and the electron transport layer, and the electron injection layer is located between the electron transport layer and the second electrode.

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