Organic electroluminescent material and organic electroluminescent device

Abstract

The invention provides an organic electroluminescent material and an organic electroluminescent device, and belongs to the field of organic electroluminescent materials, and the organic electroluminescent material has a structure as shown in a formula I. The organic electroluminescent material has low refractive index, and can be used as a luminescent auxiliary material and applied to a thicker layer in a double-layer luminescent auxiliary material, so that the organic electroluminescent material can be used as a light-emitting auxiliary material. The light emitted from the device passes through the low-refractive-index film layer of the formula I, the organic electroluminescent device prepared by matching the low-refractive-index film layer with the high-refractive-index light-emitting auxiliary material can play a better light gathering role, the light with the specific wavelength in the light emitted from the device is emitted out, the emission spectrum can be narrowed, the light-emitting intensity of the light with the specific wavelength is enhanced, and the light-emitting efficiency of the organic electroluminescent device is improved. The light loss is reduced, the luminous efficiency of the device is improved, and meanwhile, the lower driving voltage and the longer service life of the device are ensured.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic electroluminescent materials, and particularly relates to an organic electroluminescent material and an organic electroluminescent device. BACKGROUND

[0002] Organic electroluminescence refers to a phenomenon of converting electrical energy into light energy by using organic substances. The OLED (organic electroluminescent device) technology has been widely and deeply applied in many fields such as smart phones, televisions, displays and lighting due to a series of remarkable advantages such as self-luminous characteristics, high contrast, wide viewing angle and fast response speed. An organic light-emitting element utilizing the organic electroluminescence phenomenon generally has a structure including an anode and a cathode and an organic layer located between them. In order to solve the problems of lifetime and efficiency, a light-emitting auxiliary layer (multi-layer hole transport layer) is usually added between the hole transport layer and the light-emitting layer.

[0003] The light-emitting auxiliary layer can smoothly move the holes transferred from the anode to the light-emitting layer, and can block the electrons transferred from the cathode to limit the electrons in the light-emitting layer, reduce the potential barrier between the hole transport layer and the light-emitting layer, reduce the driving voltage of the organic electroluminescent device, further increase the utilization rate of holes, and thus improve the light-emitting efficiency and lifetime of the device.

[0004] There are few materials capable of forming a light-emitting auxiliary layer with excellent device performance. In particular, the lifetime and driving voltage of the OLED are not significantly improved, and the performance of the material often needs to be adjusted and improved in structure to make the device performance reach the ideal state. The performance of the device is the result of the comprehensive action of various performances, such as device structure, material refractive index, HOMO, LUMO, triplet energy level, evaporation morphology, free radical activity, carrier balance, evaporation temperature, mobility, capacitance, color deviation, test conditions (temperature, brightness, current density) and other factors. The material manufacturer improves some performance indicators to improve the performance of the organic electroluminescent device.

[0005] At present, there are very limited materials that can be used to construct a light-emitting auxiliary layer and can endow the device with excellent performance, especially in improving the lifetime and light-emitting efficiency of the OLED. With the increasing requirements of panel manufacturing enterprises on the performance of the material, it is particularly urgent to develop high-performance organic functional materials. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application aims to provide an organic electroluminescent material and an organic electroluminescent device. The compound of the present application of formula I takes 9-phenyl-9-methylfluorene substituted by Ar2 as the core (Ar2 is selected from the group consisting of phenyl, naphthyl, and biphenyl which are substituted by deuterium or unsubstituted), and is connected with an arylamine group, wherein one of the side chains of the arylamine group contains one of adamantyl, cyclohexyl, and C1-C6 alkyl (especially tert-butyl and tert-pentyl), and the obtained compound of formula I has a low refractive index. The compound of formula I of the present application with a low refractive index is used as a light-emitting auxiliary material in the thicker layer of a double-layer light-emitting auxiliary material, so that the light emitted from the device is combined with the light-emitting auxiliary material with a high refractive index through the low-refractive film layer of formula I, and the organic electroluminescent device prepared thereby can better play a role of light condensation, emit light of a specific wavelength from the light emitted from the device, narrow the emission spectrum, enhance the light-emitting intensity of light of a specific wavelength, reduce light loss, improve the light-emitting efficiency of the device, while ensuring a lower driving voltage and a longer device life.

[0007] To achieve the object of the present application, the present application adopts the following technical solutions:

[0008] In one aspect, the present application provides an organic electroluminescent material, which has a structure shown in formula I:

[0009]

[0010] wherein D is deuterium;

[0011] n is an integer selected from 0, 1, 2, 3, and 4;

[0012] R is selected from the group consisting of methyl, ethyl, propyl, and tert-butyl which are substituted by deuterium or unsubstituted;

[0013] L1 and L2 are each independently selected from a bond, and a substituted or unsubstituted C6-C24 aryl group;

[0014] L3 is selected from a substituted or unsubstituted C6-C24 aryl group;

[0015] R1 is selected from adamantyl, a substituted or unsubstituted C3-C24 cycloalkyl group, and a C1-C10 alkyl group which is substituted by deuterium or unsubstituted;

[0016] m is an integer selected from 1, 2, 3, 4, and 5;

[0017] Ar1 is selected from hydrogen, adamantyl, a substituted or unsubstituted C6-C24 aryl group, a substituted or unsubstituted C3-C24 cycloalkyl group, and a C1-C10 alkyl group which is substituted or unsubstituted;

[0018] Ar2 is selected from the group consisting of phenyl, naphthyl, and biphenyl which are substituted by deuterium or unsubstituted;

[0019] The substituents in the substituted group are selected from the following groups that are deuterated or unsubstituted: hydrogen, phenyl, biphenyl, naphthyl, methyl, ethyl, tert-butyl, and tert-pentyl.

[0020] further,

[0021] L1 and L2 are each independently selected from the following groups that are deuterated or unsubstituted, which are linked by the following groups: phenyl, methylphenyl, naphthyl, biphenyl, terphenyl;

[0022] L3 is selected from the following groups, whether substituted with deuterium or not: phenyl, methylphenyl, naphthyl, biphenyl, 9,9-dimethylfluorenyl;

[0023] R1 is selected from the following groups, whether deuterated or unsubstituted: adamantyl, cyclohexyl, methyl, ethyl, propyl, tert-butyl, tert-amyl;

[0024] Ar1 is independently selected from the following groups that are deuterated or unsubstituted, which are linked by the following: phenyl, naphthyl, biphenyl, adamantyl, cyclohexyl, methyl, ethyl, tert-butyl, tert-amyl, 9,9-dimethylfluorenyl;

[0025] Furthermore, the organic electroluminescent material has any one of the structures of formula I-1 to I-12:

[0026]

[0027] L1 is selected from the connection key;

[0028] n is selected from 0 or 5;

[0029] L2 and L3 are each independently selected from the following groups that are deuterated or unsubstituted, which are linked by the following bonds: phenyl, methylphenyl, naphthyl, biphenyl, terphenyl;

[0030] Ar1 is selected from the following groups that are connected by a linker and are either deuterated or unsubstituted: phenyl, naphthyl, biphenyl, 9,9-dimethylfluorenyl, tert-butyl, methyl;

[0031] Ar2 is selected from phenyl groups that are either deuterated or unsubstituted.

[0032] Going further,

[0033] Selected from the following groups:

[0034]

[0035] The wavy lines represent the connection sites of the functional groups.

[0036] The phrase "replaced by deuterium" refers to being partially or completely replaced by deuterium.

[0037] Preferably, the organic electroluminescent material is any one of the following compounds, but is not limited thereto:

[0038]

[0039]

[0040]

[0041]

[0042]

[0043]

[0044]

[0045]

[0046] .

[0047] Synthetic route

[0048] A series of palladium-catalyzed coupling reactions in the present application, on the one hand, make use of the activity difference of halogen I>Br>Cl, on the other hand, control the reaction site by controlling the reaction conditions, and purify the reaction by column chromatography or silica gel funnel to remove by-products to obtain the target compound.

[0049] For the raw materials not disclosed, the skilled in the art can use the classic Suzuki coupling reaction, Buchwald-Hartwig coupling reaction synthesis, butyl lithium reaction, and apply to the present application.

[0050] Reference common sense as follows:

[0051] Transition Metal Organic Chemistry (6th edition), Robert H. Crabtree, Publisher: Shanghai East China University of Technology Press, Publication Time: 2017-09-00, ISBN: 978-7-5628-5111-0, page 388.

[0052] Organic Chemistry and Optoelectronic Materials Experimental Course, Chen Runfeng, Publisher: Southeast University Press, Publication Time: 2019-11-00, ISBN: 9787564184230, page 174.

[0053] Synthesis route of formula I:

[0054] The synthesis method can be carried out by referring to one or more of the following steps:

[0055]

[0056] B' is selected from -B(OH)2 or ;

[0057] Hal1, Hal2, Hal3 are selected from chlorine, bromine or iodine;

[0058] D, n, m, Ar1, Ar2, L1, L2, L3, R, R1 are the same as defined in general formula I;

[0059] Under the nitrogen environment, the reactant I-a (1.1-1.2 eq) is dissolved in a mixed solution of toluene, ethanol and water, the reactant I-b is dissolved in a mixed solution of toluene, ethanol and water, the reactant I-b (1.0 eq) solution is slowly added to the reactant I-a solution, potassium carbonate (2-3 eq) is added, tetrakis (triphenylphosphine) palladium (0.01-0.05 eq) is added, stirred uniformly, heated to 70-90℃, and refluxed for 8-12h, purified by column chromatography to obtain the intermediate I-c;

[0060] The intermediate I-c (1.0 eq) is dissolved in toluene under nitrogen, the reactant I-d (1.1-1.3 eq) is dissolved in toluene and slowly added to the intermediate I-c solution, tris(dibenzylideneacetone)dipalladium (0.01-0.05 eq), tri-tert-butylphosphine (0.02-0.1 eq) and sodium tert-butoxide (2-3 eq) are added thereto, and the temperature is raised to 90-110°C, and the reaction is allowed to proceed for 8-12 hours, and the product is purified by column chromatography to obtain the intermediate I-e.

[0061] The intermediate I-e (1.0 eq) is dissolved in toluene under nitrogen, the reactant I-f (1.1-1.3 eq) is dissolved in toluene and slowly added to the intermediate I-e solution, tris(dibenzylideneacetone)dipalladium (0.01-0.05 eq), tri-tert-butylphosphine (0.02-0.1 eq) and sodium tert-butoxide (2-3 eq) are added thereto, and the temperature is raised to 90-110°C, and the reaction is allowed to proceed for 8-12 hours, and the product is purified by column chromatography to obtain the chemical formula I.

[0062] In another aspect, the present application provides an organic electroluminescent device including an anode, a cathode, and an organic layer disposed between the anode and the cathode, the organic layer including a light-emitting auxiliary layer, the light-emitting auxiliary layer including the organic electroluminescent material as described above.

[0063] Preferably, the organic electroluminescent device further includes at least one of a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer. The structure of the organic light-emitting element is not limited thereto, and includes a smaller or greater number of organic layers.

[0064] The compound of formula I prepared according to the present application is used as a light-emitting auxiliary layer material.

[0065] Preferably, the light-emitting auxiliary layer includes a multi-layer light-emitting auxiliary layer.

[0066] Preferably, the organic layer includes a hole transport layer and a light-emitting auxiliary layer, the light-emitting auxiliary layer includes a first light-emitting auxiliary layer and a second light-emitting auxiliary layer, the first light-emitting auxiliary layer includes the organic electroluminescent material as described above, and the first light-emitting auxiliary layer is disposed between the hole transport layer and the second light-emitting auxiliary layer.

[0067] As for the compound of formula I, in the manufacture of the organic light-emitting element, the organic layer is formed using a vacuum evaporation method or a solution coating method. Among them, the solution coating method includes a spin coating method, a dip coating method, a doctor blade coating method, an inkjet printing method, a screen printing method, a spray method, and a roll coating method, but is not limited thereto.

[0068] The organic light-emitting element of the present application is classified into a top emission type, a bottom emission type, or a dual emission type depending on the material used.

[0069] The devices of this invention are used in organic electroluminescent devices, including but not limited to flat panel displays, computer monitors, medical monitors, televisions, billboards, lamps for internal or external lighting and / or signals, head-up displays, fully transparent or partially transparent displays, flexible displays, laser printers, telephones, mobile phones, tablets, photo albums, personal digital assistants (PDAs), wearable devices, laptops, digital cameras, camcorders, viewfinders, microdisplays, 3D displays, virtual reality or augmented reality displays, vehicles, video walls including multiple displays tiled together, theater or stadium screens, phototherapy devices, and signs.

[0070] As the anode material, a material with a high work function is selected to facilitate the injection of holes into the organic layer. Specific examples of anode materials that can be used in this invention include vanadium, chromium, copper, zinc, gold or their alloys; metal oxides such as zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); combinations of metals and oxides such as ZnO:Al or SnO2:Sb; and conductive polymers such as polypyrrole and polyaniline.

[0071] The hole injection layer is selected as a p-doped hole injection layer, which means a hole injection layer doped with p-doped agents. P-doped agents are materials that can impart p-type semiconductor characteristics. P-type semiconductor characteristics refer to the characteristics of injecting or transporting holes at the HOMO energy level, that is, the characteristics of materials with high hole conductivity.

[0072] Hole transport material is a material capable of receiving holes from the anode or hole injection layer and transporting the holes to the light-emitting layer, and the hole transport material is a material with high hole mobility. The hole transport material is selected from aryl amine derivatives, conductive polymers, and block copolymers that simultaneously contain conjugated and non-conjugated parts.

[0073] An auxiliary light-emitting layer (multilayer hole transport layer) is added between the hole transport layer and the light-emitting layer. The auxiliary light-emitting layer primarily assists the hole transport layer and is therefore sometimes referred to as a second hole transport layer. This layer allows holes transferred from the anode to smoothly move to the light-emitting layer and blocks electrons transferred from the cathode, confining them within the light-emitting layer. This reduces the potential barrier between the hole transport layer and the light-emitting layer, lowers the driving voltage of the organic light-emitting device, and further increases hole utilization, thereby improving the device's luminous efficiency and lifetime.

[0074] The luminescent material in the luminescent layer is a material that can receive holes and electrons from the hole transport layer and the electron transport layer respectively, and combine them to emit light in the visible light region. The material with high quantum efficiency for fluorescence or phosphorescence is selected.

[0075] The light-emitting layer comprises a host material and a dopant material, and the mass ratio of the host material to the dopant material is 90-99.5:0.5-10.

[0076] The host material is an aromatic condensed ring derivative or a heterocyclic compound. Specifically, the aromatic condensed ring derivative includes an anthracene derivative, a pyrene derivative, a naphthalene derivative, a pentacene derivative, a phenanthrene compound or a fluoranthene compound, and the heterocyclic compound includes a carbazole derivative, a dibenzofuran derivative or a pyrimidine derivative.

[0077] The dopant material includes fluorescent doping and phosphorescent doping, and is specifically selected from an aromatic amine derivative, a styryl amine compound, a boron complex, a fluoranthene compound or a metal complex.

[0078] The electron transport layer can function to facilitate electron transport, and the electron transport material is a material that advantageously receives electrons from the cathode and transports the electrons to the light-emitting layer, and is specifically selected from a material having a high electron mobility; and the electron transport layer includes an electron buffer layer, a hole blocking layer and an electron transport layer.

[0079] The electron injection layer can function to facilitate electron injection, and has the ability to transport electrons to prevent excitons generated in the light-emitting layer from migrating to the hole injection layer. The material of the electron injection layer includes oxazole, oxadiazole, triazole, imidazole, perylene tetracarboxylic acid, fluorenyl methane, anthrone and derivatives thereof, magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, ytterbium or alloys thereof, a metal complex or a nitrogen-containing 5-membered ring derivative, but is not limited thereto.

[0080] The cathode is selected to have a small work function to allow smooth injection of electrons into the organic material layer, and the thickness of the layer is between 0.5 and 5 nm. Specifically, the cathode material includes magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin and lead or alloys thereof: LiF / Al or LiO2 / Al, Mg / Ag multilayer structure material.

[0081] In addition to the light-emitting auxiliary layer disclosed in the present application, the material of other layers in the OLED device is not particularly limited. Existing hole injection materials, hole transport materials, hole transport auxiliary materials, dopant materials, hole blocking layer materials, electron transport layer materials and electron injection materials can be used.

[0082] Compared with the prior art, the present application has the following beneficial effects:

[0083] The compound of the present application is formula I, which takes 9-phenyl-9-methylfluorene substituted by Ar2 as the core (Ar2 is selected from phenyl, naphthyl, biphenyl, which are substituted by deuterium or unsubstituted), and is connected with arylamine group, wherein one of the side chains of arylamine group contains one of adamantane, cyclohexyl, C1-C6 alkyl (especially tert-butyl, tert-pentyl), and the obtained compound of formula I has low refractive index.

[0084] The compound of the present application of formula I with low refractive index is applied in the thicker layer of the double-layer light-emitting auxiliary material as a light-emitting auxiliary material, so that the light emitted from the device is matched with the high-refractive light-emitting auxiliary material through the low-refractive film layer of formula I, and the organic electroluminescent device prepared by the matching can better play the role of light collection, emit the light of specific wavelength from the light emitted from the device, narrow the emission spectrum, enhance the light-emitting intensity of the light of specific wavelength, reduce the light loss, improve the light-emitting efficiency of the device, while ensuring lower driving voltage and longer device life. BRIEF DESCRIPTION OF DRAWINGS

[0085] Figure 1 The nuclear magnetic resonance hydrogen spectrum of compound 1. DETAILED DESCRIPTION

[0086] The technical solutions of the present application are further illustrated by the specific embodiments. It should be understood by those skilled in the art that the embodiments are only used to help understand the present application, and should not be regarded as specific limitation to the present application.

[0087] Example 1: Synthesis of compound 1

[0088]

[0089] CAS: reactant 1-a: 3070970-02-1;

[0090] CAS: reactant 1-b: 1459-48-9;

[0091] CAS: reactant 1-d: 98974-71-1.

[0092] Under the nitrogen environment, the reactant 1-a (1.0 eq) is dissolved in toluene, the reactant 1-b (1.2 eq) is dissolved in toluene, and is slowly added to the solution of intermediate I-c, and then the tris(dibenzylideneacetone) dipalladium (0.01 eq), tri-tert-butyl phosphine (0.02 eq) and sodium tert-butyl alcohol (2.2 eq) are added, and the temperature is increased to 100℃, and the reaction is carried out for 8h, and the column chromatography is used for purification, to obtain the intermediate 1-c (yield: 83.4%);

[0093] under nitrogen, the intermediate 1-c (1.0 eq) was dissolved in toluene, the reactant 1-d (1.3 eq) was dissolved in toluene and slowly added to the intermediate 1-c solution, to which tris(dibenzylideneacetone)dipalladium (0.01 eq), tri-tert-butylphosphine (0.02 eq) and sodium tert-butoxide (2.4 eq) were added, and the temperature was raised to 100 °C, and the reaction was allowed to proceed for 8 h, and purified by column chromatography to obtain the chemical formula 1 (yield: 79.6%, test value MS (ESI, m / Z): [M+H] + = 709.52).

[0094] Characterization:

[0095] The nuclear magnetic resonance hydrogen spectrum of the compound 1 is shown in Figure 1 .

[0096] HPLC purity: >99.8%.

[0097] Elemental analysis:

[0098] Theoretical value: C, 91.35; H, 6.67; N, 1.97

[0099] Test value: C, 91.16; H, 6.84; N, 2.06.

[0100] Example 2: Synthesis of compound 385

[0101]

[0102] CAS: Reactant 1-385: 2606032-01-1.

[0103] under nitrogen, the reactant 385-a (1.0 eq) was dissolved in toluene, the reactant 385-b (1.2 eq) was dissolved in toluene and slowly added to the intermediate 385-c solution, to which tris(dibenzylideneacetone)dipalladium (0.01 eq), tri-tert-butylphosphine (0.03 eq) and sodium tert-butoxide (2.4 eq) were added, and the temperature was raised to 100 °C, and the reaction was allowed to proceed for 8 h, and purified by column chromatography to obtain the intermediate 385-c (yield: 81.9%);

[0104] under nitrogen, the intermediate 385-c (1.0 eq) was dissolved in toluene, the reactant 385-d (1.2 eq) was dissolved in toluene and slowly added to the intermediate 385-c solution, to which tris(dibenzylideneacetone)dipalladium (0.01 eq), tri-tert-butylphosphine (0.03 eq) and sodium tert-butoxide (2.3 eq) were added, and the temperature was raised to 100 °C, and the reaction was allowed to proceed for 8 h, and purified by column chromatography to obtain the chemical formula 385 (yield: 77.5%, test value MS (ESI, m / Z): [M+H] += 709.44).

[0105] Characterization:

[0106] HPLC purity: >99.8%.

[0107] Elemental analysis:

[0108] Theoretical value: C, 91.35; H, 6.67; N, 1.97

[0109] Test value: C, 91.22; H, 6.79; N, 2.02.

[0110] In addition, it should be noted that other compounds of the present application can be obtained by referring to the above-mentioned synthesis methods of the listed examples, and therefore will not be listed one by one. In the present application, the mass spectrometer used for mass spectrometry testing is Waters XEVO TQD, low precision, ESI source testing.

[0111] Refractive index test

[0112] Preparation of single-layer film for optical property evaluation

[0113] The compound of formula I (see Table 1 for compounds of the present application), comparative compounds 1-24 were respectively made into an evaporation film with a thickness of 50 nm on a silicon substrate, and the refractive index n and extinction coefficient k values at a wavelength of 530 nm were measured. The structures of comparative compounds 1-24 are as follows, and the test data are shown in Table 1:

[0114]

[0115]

[0116]

[0117] Table 1 Refractive index n and extinction coefficient k test results

[0118]

[0119]

[0120] In the refractive index test at 530 nm, the refractive index of the compound of formula I of the present application is between 1.62-1.66, and the refractive index of the comparative compound is between 1.75-1.78. Under similar structures, the refractive index is reduced by about 0.09-0.16, and the extinction coefficient k value is almost 0 in each color domain, which does not affect the light emission of the light-emitting layer.

[0121] The compound of formula I of the present application takes 9-phenyl-9-methylfluorene substituted by Ar2 as the core (Ar2 is selected from phenyl, naphthyl, biphenyl substituted by deuterium or unsubstituted), and is connected with arylamine group, wherein one of the side chains of arylamine group contains one of adamantane, cyclohexyl, C1-C6 alkyl (especially tert-butyl, tert-pentyl), and the obtained compound of formula I has low refractive index.

[0122] The compound of formula I of the present application with low refractive index is applied in the thicker layer of the double-layer light-emitting auxiliary material, so that the light emitted from the device is matched with the high-refractive light-emitting auxiliary material through the low-refractive film layer of formula I, and the organic electroluminescent device prepared by the matching can better play the role of light collection, emit the light of specific wavelength from the light emitted from the device, narrow the emission spectrum, enhance the light-emitting intensity of the light of specific wavelength, reduce the light loss, improve the light-emitting efficiency of the device, while ensuring lower driving voltage and longer device life.

[0123] The application of the low-refractive material of formula I provided by the present application in the organic electroluminescent device is described below in combination with specific application examples.

[0124] Preparation of green organic electroluminescent device:

[0125] a, ITO anode: ITO (indium tin oxide)-Ag-ITO (indium tin oxide) glass substrate, coating thickness is 14 nm / 150 nm / 14 nm, washed in distilled water for 2 times, ultrasonic washing for 30 min, then washed repeatedly in distilled water for 2 times, ultrasonic washing for 10 min, after washing, transferred to the spin dryer for spin-drying, finally baked in vacuum oven at 220℃ for 2 hours, after baking, cooled and ready for use; using the substrate as anode, using the evaporation machine to perform evaporation device process, and then evaporating other functional layers on the substrate.

[0126] b, HIL (hole injection layer): 1 / s of evaporation rate, vacuum evaporating hole injection layer materials HT1 and P-dopant, the evaporation rate ratio of HT1 and P-dopant is 95:5, and the thickness is 10 nm;

[0127] c, HTL (hole transport layer): 1.0 / s of evaporation rate, vacuum evaporating 130 nm of HT1 on the hole injection layer as the hole transport layer;

[0128] d, light-emitting auxiliary layer-1: 1.0 / s of evaporation rate, vacuum evaporating 40 nm of the compound of formula I provided by the present application on the hole transport layer as light-emitting auxiliary layer-1;

[0129] e, light-emitting auxiliary layer-2: 1.0 The prime-2 is vacuum evaporated on the light-emitting auxiliary layer-1 as the light-emitting auxiliary layer-2 at a rate of 0.5 A / s.

[0130] f. EML (emitting layer): Then, the host material (Host-1 and Host-2) and the dopant material (Dopant-G) are vacuum evaporated on the light-emitting auxiliary layer at a rate of 1 A / s to form the emitting layer with a thickness of 40 nm, wherein the Host-1 and Host-2 are co-evaporated with the dopant material as the double host material, and the ratio of Host-1 and Host-2 is 50:50. The evaporation rate ratio of the host material and the dopant is 90:10.

[0131] g. HBL (hole blocking layer): The HB-1 is vacuum evaporated on the emitting layer as the hole blocking layer at a rate of 0.5 A / s with a thickness of 5.0 nm.

[0132] h. ETL (electron transport layer): The ET-1 and Liq are vacuum evaporated on the hole blocking layer as the electron transport layer at a rate of 1 A / s with a thickness of 30 nm. The evaporation rate ratio of the ET-1 and Liq is 50:50.

[0133] i. EIL (electron injection layer): The Yb is vacuum evaporated on the electron transport layer as the electron injection layer at a rate of 0.5 A / s with a thickness of 1.0 nm.

[0134] j. Cathode: The magnesium and silver are vacuum evaporated on the electron injection layer as the cathode at a rate of 1 A / s with a thickness of 13 nm. The evaporation rate ratio of the magnesium and silver is 1:9.

[0135] k. Light extraction layer: The CPL-1 is vacuum evaporated on the cathode as the light extraction layer at a rate of 1 A / s with a thickness of 60 nm.

[0136] l. The substrate after the evaporation is packaged. First, the cleaned cover plate is coated with UV glue by using a gluing device, then the coated cover plate is moved to the pressing section, the substrate after the evaporation is placed on the end of the cover plate, and finally the substrate and the cover plate are bonded under the action of the bonding device, and the UV glue is cured by light at the same time.

[0137] The structural formula of the raw material required by each layer is as follows:

[0138] .

[0139] Application Examples 1-141

[0140] ​​​​​​The organic electroluminescent devices of application examples 1-141 were prepared according to the preparation method of the above organic electroluminescent device, except that the compound of formula I in application example 1 was replaced by the corresponding compound (see Table 2 for the compounds involved) to form a light-emitting auxiliary layer.

[0141] Comparative examples 1-24

[0142] The organic electroluminescent devices of comparative examples 1-24 were prepared according to the preparation method of the above organic electroluminescent device of application example 1, except that the compound of formula I in application example 1 was replaced by the corresponding comparative compound (see Table 2 for the comparative compounds 1-24 involved) to form a light-emitting auxiliary layer.

[0143] The driving voltage, luminous efficiency and lifetime of the organic electroluminescent devices obtained from the above device application example 1 and device comparative examples 1-24 were characterized at a brightness of 15000 (nits), and the test results are as follows in Table 2.

[0144] Table 2 Test results of luminescent properties (brightness value is 15000 nits)

[0145]

[0146]

[0147] The compound of formula I of the present application takes 9-phenyl-9-methylfluorene substituted by Ar2 as the core (Ar2 is selected from phenyl, naphthyl, biphenyl, which are substituted by deuterium or unsubstituted), and is connected with an arylamine group, wherein one of the side chains of the arylamine group contains one of adamantane, cyclohexyl, C1-C6 alkyl (especially tert-butyl, tert-pentyl), and the obtained compound of formula I has a low refractive index. The interaction between the low refractive index compound of the present application and the high refractive index compound makes the light condensation of the device more significant, and the performance of the device is improved in efficiency and lifetime.

[0148] The main difference between comparative compounds 1-comparative compounds 7 and the compound of formula I of the present application in the prior art is that there is no phenyl group at the 9 position of fluorene; wherein comparative compound 3 and the compound 408 of the present application, comparative compound 7 and the compound 427 of the present application are parallel comparative compounds; the introduction of a rigid aromatic ring at 9 of 9-phenyl-9-methylfluorene can form an excited dimer and achieve strong charge resonance stabilization, which can improve the electron transport efficiency and is beneficial to the improvement of the light-emitting efficiency.

[0149] The main difference between the comparative compounds 8-13 and the compounds of formula I of the present application is that the 9-phenyl-9-methylfluorene is not substituted by Ar2; wherein, the comparative compound 9 is parallel to the compound 78 of the present application, the comparative compound 10 is parallel to the compound 7 of the present application, the comparative compound 11 is parallel to the compound 11 of the present application, the comparative compound 12 is parallel to the compound 79 of the present application, the comparative compound 13 is parallel to the compound 87 of the present application; the substituents of Ar2 work together to make the compound not easy to crystallize in the device, and have better light emission characteristics

[0150] The compounds provided by the present application exhibit higher light emission efficiency and longer service life under the same device conditions.

[0151] The main difference between the comparative compounds 14-20 and the compounds of formula I of the present application is that the arylamine side chain does not contain one of adamantane, cyclohexyl, and C1-C6 alkyl; wherein, the comparative compound 14 is parallel to the compound 7 of the present application, the comparative compound 16 is parallel to the compound 100 of the present application, the comparative compound 17 is parallel to the compound 181 of the present application, the comparative compound 18 is parallel to the compound 11 of the present application, the comparative compound 19 is parallel to the compound 57 of the present application; wherein, the adamantane, cyclohexyl, and C1-C6 alkyl in the side chain have no conjugation, which reduces the refractive index of the compound.

[0152] The comparative compounds 21-24 are similar to the compounds of formula I of the present application, but there are differences in the parent nucleus and the side chain.

[0153] From the test results in Table 2, the driving voltage of the comparative compounds is between 3.5-3.6V, the efficiency is between 166-168 cd / A, and the service life is between 820-840h. The compounds of formula I of the present application have higher light emission efficiency, longer service life, and lower driving voltage.

[0154] When the compound of the present application contains adamantane in the side chain, the efficiency is improved more significantly, the efficiency is generally between 178-181 cd / A, and the service life is between 900-925h; when the side chain contains alkyl (especially tert-butyl and tert-pentyl), the service life is between 960-980h, which is significantly improved.

[0155] The organic electroluminescent material and the organic electroluminescent device of the present application are illustrated by the above examples, but the present application is not limited to the above examples, i.e. it does not mean that the present application must rely on the above examples to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of the selected materials of the present application, addition of auxiliary ingredients, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. An organic electroluminescent material, characterized in that, The organic electroluminescent material has a structure shown in Formula I: ； D is deuterium; n is an integer selected from 0, 1, 2, 3, 4, and 5; R is selected from the following groups substituted or unsubstituted by deuterium: methyl, ethyl, propyl, t-butyl; L1 and L2 are each independently selected from a bond, a substituted or unsubstituted C6-C24 aryl group; L3 is selected from a substituted or unsubstituted C6-C24 aryl group; R1 is selected from adamantyl, a substituted or unsubstituted C3-C24 cycloalkyl group, a C1-C10 alkyl group substituted or unsubstituted by deuterium; m is an integer selected from 1, 2, 3, 4, and 5; Ar1 is selected from hydrogen, adamantyl, a substituted or unsubstituted C6-C24 aryl group, a substituted or unsubstituted C3-C24 cycloalkyl group, and a substituted or unsubstituted C1-C10 alkyl group; Ar2 is selected from the following groups substituted or unsubstituted by deuterium: phenyl, naphthyl, and biphenyl; The substituents in the substituted groups are selected from the following groups substituted or unsubstituted by deuterium: hydrogen, phenyl, biphenyl, naphthyl, methyl, ethyl, t-butyl, and t-amyl.

2. The organic electroluminescent material according to claim 1, characterized in that L1 and L2 are each independently selected from a bond, a substituted or unsubstituted C6-C24 aryl group, and the following groups substituted or unsubstituted by deuterium: phenyl, methylphenyl, naphthyl, and biphenyl; L3 is selected from the following groups substituted or unsubstituted by deuterium: phenyl, methylphenyl, naphthyl, biphenyl, and 9,9-dimethylfluorenyl; R1 is selected from the following groups substituted or unsubstituted by deuterium: adamantyl, cyclohexyl, methyl, ethyl, propyl, t-butyl, and t-amyl; Ar1 is each independently selected from a bond, the following groups substituted or unsubstituted by deuterium: phenyl, naphthyl, biphenyl, adamantyl, cyclohexyl, methyl, ethyl, t-butyl, t-amyl, and 9,9-dimethylfluorenyl.

3. The organic electroluminescent material according to claim 1, characterized in that The organic electroluminescent material has any one of structures of Formula I-1 to Formula I-12: ； L1 is selected from a bond; n is selected from 0 or 5; L2 and L3 are each independently selected from a bond, the following groups substituted or unsubstituted by deuterium: phenyl, methylphenyl, naphthyl, biphenyl, and terphenyl; Ar1 is selected from a bond, the following groups substituted or unsubstituted by deuterium: phenyl, naphthyl, biphenyl, 9,9-dimethylfluorenyl, t-butyl, and methyl; Ar2 is selected from phenyl substituted or unsubstituted by deuterium.

4. The organic electroluminescent material according to claim 1, characterized in that selected from the group consisting of: ； The wavy line represents a connection site of a group.

5. The organic electroluminescent material according to claim 1, characterized in that, The organic electroluminescent material is any one of the following compounds: 。 6. An organic electroluminescent device, characterized by The organic electroluminescent device comprises an anode, a cathode, and an organic layer disposed between the anode and the cathode, wherein the organic layer comprises a light-emitting auxiliary layer, and the light-emitting auxiliary layer comprises the organic electroluminescent material according to any one of claims 1-5.

7. The organic electroluminescent device according to claim 6, characterized in that The light-emitting auxiliary layer comprises a multi-layer light-emitting auxiliary layer.

8. The organic electroluminescent device according to claim 6, characterized in that The organic layer comprises a hole transport layer and a light-emitting auxiliary layer, wherein the light-emitting auxiliary layer comprises a first light-emitting auxiliary layer and a second light-emitting auxiliary layer, the first light-emitting auxiliary layer comprises the organic electroluminescent material according to any one of claims 1-5, and the first light-emitting auxiliary layer is disposed between the hole transport layer and the second light-emitting auxiliary layer.

9. The organic electroluminescent device according to claim 8, characterized in that The organic electroluminescent device further comprises at least one of a hole injection layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, and an electron injection layer.

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