CN115850217B - Organic electroluminescent compound and preparation method and application thereof - Google Patents

Abstract

The invention discloses an organic electroluminescent compound, a preparation method and application thereof, which belong to the technical field of organic photoelectric materials, and the structural general formula is shown as a specification formula 1. Therefore, the crystallinity is possibly reduced due to the reduction of intermolecular interaction, the aggregation and accumulation of molecules are reduced, the blocking phenomenon in evaporation is reduced, meanwhile, the intermolecular interaction is weakened, the evaporation temperature of a compound of a material can be reduced, and the change of the chemical structure of the material caused by long-time heating is avoided. Due to the fact that the conjugated system is properly prolonged, aggregation of molecules is reduced, electron localization is avoided, carrier transmission traps are not easy to form, migration of holes is facilitated, and the service life and luminous efficiency of the obtained OLED device are further improved.

Description

Organic electroluminescent compound and preparation method and application thereof

Technical Field

The invention belongs to the technical field of organic photoelectric materials, and particularly relates to an organic electroluminescent compound, a preparation method and application thereof.

Background

A small-molecule green organic electroluminescent device (OLED) was first developed by Tang et al from Eastman Kodak, inc. Thereafter, the development of the OLED is rapidly affected and the OLED has been commercialized. The organic electroluminescent device converts electric energy into light by applying electric power to an organic light emitting material, and generally includes an anode, a cathode, and an organic layer formed between the two electrodes. The organic layer of the OLED may include a hole injection layer, a hole transport layer, a hole assist layer, a light emitting assist layer, an electron blocking layer, a light emitting layer (containing a host and dopant materials), an electron buffer layer, a hole blocking layer, an electron transport layer, an electron injection layer, and the like. The material used in the organic layer may be functionally classified into a hole injecting material, a hole transporting material, a hole assisting material, a light emitting assisting material, an electron blocking material, a light emitting material, an electron buffering material, a hole blocking material, an electron transporting material, an electron injecting material, and the like.

The evaporation of the organic functional layer material needs to be performed at a high temperature, but a phenomenon in which the organic functional layer material is deteriorated frequently occurs at a high temperature. One of the causes of deterioration of the organic functional layer material is: the material structure causes the material evaporation temperature to increase, and the long-time heating causes the material chemical structure to change. In addition, the form of the organic functional layer material in the device is an amorphous disordered film, and the form of the film formed by evaporation affects the evaporation temperature, the service life of the OLED device and the luminous efficiency. Therefore, it is important to develop higher-performance organic functional materials to meet the requirements of panel manufacturing enterprises in mass production of organic electroluminescent displays.

Disclosure of Invention

In view of the above, the present invention provides an organic electroluminescent compound, a preparation method and application thereof.

In order to achieve the above purpose, the present invention adopts the following technical scheme:

an organic electroluminescent compound has a structural general formula shown in formula 1:

formula 1;

in the formula 1, a substituent condensed at any position on a benzene ring at the position of a ring A is independently selected from phenyl;

l is selected from any one of single bond and phenyl.

Further, the above formula 1 is selected from the following general formulas:

。

further, the above formula 1 is selected from the following general formulae:

。

preferably, the above formula 1 is selected from the following general formulae:

。

more preferably, the organic electroluminescent compound according to formula 1 has any one of the following structures:

。

the invention also provides a preparation method of the organic electroluminescent compound, which comprises the following steps:

when L is phenyl, the synthetic route is:

(1) Dissolving raw material A in toluene, dissolving raw material B in toluene, slowly adding the solution of raw material B into the solution of raw material A, and adding N ₂ Adding a palladium catalyst, a phosphorus ligand and salt under the atmosphere, heating to 90-115 ℃ and stirring for reaction for 4-12h, filtering with diatomite while the reaction is hot after the reaction is finished, removing the salt and the palladium catalyst, cooling the filtrate to room temperature, adding distilled water into the filtrate for washing, retaining an organic phase after liquid separation, extracting an aqueous phase with ethyl acetate, drying the combined organic layer with magnesium sulfate, removing a solvent with a rotary evaporator, and purifying the residual substances with column chromatography with a mixture of dichloromethane and petroleum ether as an eluent to obtain an intermediate 1;

(2) Dissolving the intermediate 1 in a mixed solution of toluene, ethanol and water, dissolving a raw material C in a mixed solution of toluene, ethanol and water, slowly adding the solution of the raw material C into the solution of the intermediate 1, adding a palladium catalyst and salt under the protection of nitrogen, uniformly stirring, heating to 80 ℃, carrying out reflux reaction for 5-7 hours, retaining an organic phase after the solution is cooled to room temperature, and extracting an aqueous phase with ethyl acetate; after the organic phases are combined, drying is carried out by using anhydrous magnesium sulfate, a rotary evaporator is used for removing a solvent to obtain a solid organic matter, dichloromethane is used for completely dissolving the solid organic matter, then the solid organic matter is slowly dripped into a petroleum ether solution, stirring is uniform, precipitation is carried out, a solid is obtained through suction filtration, absolute ethyl alcohol and petroleum ether are sequentially used for leaching, and drying is carried out to obtain an intermediate 2;

(3) Dissolving intermediate 2 in toluene, dissolving raw material D in toluene, slowly adding solution of raw material D into solution of intermediate 2, and adding the solution of raw material D into solution of intermediate 2, wherein N is ₂ Adding palladium catalyst, phosphorus ligand and salt under atmosphere, heating to 90deg.C, stirring for 4-12 hr, vacuum filtering with diatomite, removing salt and catalyst, cooling filtrate to room temperature, adding distilled water into filtrate, washing, separating to obtain organic phase, and collecting filtrate with acetic acidEthyl ester extraction of the aqueous phase, drying of the combined organic layers using magnesium sulfate, removal of solvent using a rotary evaporator, and finally purification of the remaining material by column chromatography using a mixture of dichloromethane and petroleum ether as eluent to afford intermediate 3;

(4) Dissolving intermediate 3 in toluene, dissolving raw material E in toluene, slowly adding solution of raw material E into solution of intermediate 3, and adding N ₂ Adding a palladium catalyst, a phosphorus ligand and salt under the atmosphere, heating to 90-120 ℃ and stirring for reaction for 4-12h, filtering with diatomite while the reaction is hot after the reaction is finished, removing the salt and the catalyst, cooling the filtrate to room temperature, adding distilled water into the filtrate for washing, retaining an organic phase after liquid separation, extracting an aqueous phase with ethyl acetate, drying the combined organic layer with magnesium sulfate, removing a solvent with a rotary evaporator, and purifying the residual substances with column chromatography with a mixture of dichloromethane and petroleum ether as an eluent to obtain a compound shown in a formula 1;

or, when L is a single bond, the synthetic route is:

1) Dissolving raw material A in toluene, dissolving raw material D in toluene, slowly adding the solution of raw material D into the solution of raw material A, and adding the solution of raw material D into N ₂ Adding a palladium catalyst, a phosphorus ligand and salt under the atmosphere, heating to 90 ℃ and stirring for reaction for 4-12h, filtering with diatomite while the reaction is hot after the reaction is finished, removing the salt and the catalyst, cooling the filtrate to room temperature, adding distilled water into the filtrate for washing, separating liquid to keep an organic phase, extracting an aqueous phase with ethyl acetate, drying the combined organic layer with magnesium sulfate, removing a solvent with a rotary evaporator, and finally purifying the residual substances with column chromatography with a mixture of dichloromethane and petroleum ether as an eluent to obtain an intermediate 3;

2) Dissolving intermediate 3 in toluene, dissolving raw material E in toluene, slowly adding solution of raw material E into solution of intermediate 3, and adding N ₂ Atmosphere down additionAdding a palladium catalyst, a phosphorus ligand and salt, heating to 90-120 ℃ and stirring for reaction for 4-12h, filtering with diatomite while the reaction is hot after the reaction is finished, removing the salt and the catalyst, cooling the filtrate to room temperature, adding distilled water into the filtrate for washing, separating liquid to keep an organic phase, extracting an aqueous phase with ethyl acetate, drying the combined organic layer with magnesium sulfate, removing a solvent with a rotary evaporator, and finally purifying the residual substances with column chromatography with a mixture of dichloromethane and petroleum ether as an eluent to obtain a compound shown in formula 1;

the above Hal1-Hal4 are each independently selected from fluorine, chlorine, bromine or iodine.

Further, the palladium catalyst is Pd ₂ (dba) ₃ 、Pd(PPh ₃ ) ₄ Or palladium acetate.

Further, the above phosphorus ligand is P (t-Bu) ₃ Or X-phos.

Further, the above salt is t-BuONa, potassium carbonate or cesium carbonate.

Further, the mixture of dichloromethane and petroleum ether is used as an eluent, and the volume ratio of the dichloromethane to the petroleum ether is 6:4.

Further, in the step (1), the molar ratio of the raw material A, the raw material B, the palladium catalyst, the phosphorus ligand and the salt is 1.0eq:1.0:0.01:0.05:2.0;

in the step (2), the molar ratio of the intermediate 1, the raw material C, the palladium catalyst and the salt is 1.0:1.0:0.01:2.0;

in the step (3), the molar ratio of the intermediate 2, the raw material D, the palladium catalyst, the phosphorus ligand and the salt is 1.0:1.0:0.01:0.05:2.0;

in the step (4), the molar ratio of the intermediate 3 to the raw material E to the palladium catalyst to the phosphorus ligand to the salt is 1.0:1.0:0.01:0.05:2.0.

In the step (2), the volume ratio of toluene, ethanol and water in the mixed solution is 3:1:1.

Further, in step 1), the molar ratio of the raw material A, the raw material D, the palladium catalyst, the phosphorus ligand and the salt is 1.0:1.0:0.01:0.05:2.0.

Further, in step 2), the molar ratio of the intermediate 3 to the raw material E to the palladium catalyst to the phosphorus ligand to the salt is 1.0:1.0:0.01:0.05:2.0.

Further, the raw material E is synthesized by adopting a Suzuki coupling reaction and/or a Buchwald-Hartwig coupling reaction.

Further, the raw material E is obtained by reacting Ar-X with p-phenyldiboronic acid/boric acid ester in a molar ratio of 1:1 and then reacting with dihalobenzene, wherein X is selected from halogen.

Description: the preparation of the target structural intermediate is realized by utilizing the characteristic that the reactive I is larger than Br and is larger than Cl in the Buchwald-Hartwig coupling reaction in the presence of two halogens in the raw material C, and the target compound is obtained by purifying the reaction by using a column chromatography or a silica gel funnel and removing byproducts. The reaction mechanism is as follows:

transition metal organic chemistry (original sixth edition), robert H-Crabtree (Robert H. Crabtree), press: publication time of Shanghai Shandong university Press: 2017-09-00, ISBN:978-7-5628-5111-0, page 388.

Organic chemistry and photoelectric Material Experimental Instructions, chen Runfeng, press: university of east south Press, publication time: 2019-11-00, ISBN:9787564184230, page 174.

The invention has the following beneficial effects: the compound provided by the invention changes the position of the substituent group, so that the dihedral angle of the compound is increased, and the molecular configuration is more distorted, thereby reducing molecular aggregation and accumulation, improving the migration of holes, and further being not easy to form carrier transmission traps. In this way, the crystallinity may be reduced due to the reduction of the intermolecular interaction, the aggregation and accumulation of molecules are reduced, the blocking phenomenon in evaporation is reduced, and meanwhile, the intermolecular interaction is weakened, so that the evaporation temperature of a compound of a material can be reduced, and the chemical structure of the material is prevented from being changed due to long-time heating. On the other hand, as the conjugated system is properly prolonged, the aggregation of molecules is reduced, the localization of electrons is avoided, carrier transport traps are not easy to form, the migration of holes is facilitated, the service life and the luminous efficiency of the obtained OLED device are further improved, and the requirement of mass production of the organic electroluminescent display is met.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a nuclear magnetic resonance hydrogen spectrum of Compound 1;

FIG. 2 is a nuclear magnetic resonance hydrogen spectrum of compound 54;

FIG. 3 is a nuclear magnetic resonance hydrogen spectrum of compound 181;

FIG. 4 is a graph showing the comparison of the state of the materials after evaporation of the compound of the present invention and the comparison compound for 100 hours;

FIGS. 5-1 and 5-2 are graphs of simulated film disordered bulk density by the NPT method in molecular dynamics.

Detailed Description

The following description of the technical solutions in the embodiments of the present invention will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Example 1

This example provides a process for the preparation of compound 1, specifically as follows:

raw material A-1 (1.0 eq) (CAS: 2103931-83-3) was dissolved in toluene, raw material D-1 (1.0 eq) (CAS: 1795019-74-7) was dissolved in toluene, then a solution of raw material D-1 was slowly added to the solution of raw material A-1, and the mixture was stirred under N ₂ Pd addition under atmosphere ₂ (dba) ₃ (0.01 eq), X-phos (0.05 eq) and t-Buona (2.0 eq), heating to 90℃and stirring the reaction 5h, after the reaction is finished, the diatomite is used for carrying out suction filtration while the diatomite is hot, salt and catalyst are removed, after the filtrate is cooled to room temperature, distilled water is added into the filtrate for washing, an organic phase is reserved after liquid separation, an aqueous phase is extracted by ethyl acetate, then the combined organic layers are dried by using magnesium sulfate, and a rotary evaporator is used for removing the solvent. Finally, the remaining material was purified by column chromatography using a mixture of dichloromethane and petroleum ether as eluent to give intermediate 3 (yield: 92.4%).

Intermediate 3 (1.0 eq) was dissolved in toluene, starting material E-1 (1.0 eq) (CAS: 207612-71-3) was dissolved in toluene, then the solution of starting material E-1 was slowly added to the solution of intermediate 3, at N ₂ Pd addition under atmosphere ₂ (dba) ₃ （0.01eq）、P(t-Bu) ₃ (0.05 eq) and t-BuONa (2.0 eq), heating to 90 ℃ and stirring for reaction for 5h, filtering with diatomaceous earth while hot after the reaction is finished, removing salt and catalyst, cooling the filtrate to room temperature, adding distilled water to the filtrate for washing, separating the liquid to leave an organic phase, extracting the aqueous phase with ethyl acetate, then drying the combined organic layers with magnesium sulfate, and removing the solvent with a rotary evaporator. Finally, the remaining material was purified by column chromatography using a mixture of dichloromethane and petroleum ether as eluent to give compound-1 (yield: 91.3%).

The resulting compound 1 was characterized as follows:

HPLC purity: > 99.7%.

Mass spectrometry test: (the mass spectrum is tested by using an ultra-high liquid phase mass spectrometer and an ESI source, the same as follows)

Theoretical value 663.82; the test value was 663.97.

Elemental analysis:

theoretical value: c, 90.47, H, 5.01, N, 2.11, O, 2.41;

test value: c, 90.22, H, 5.18, N, 2.34, O, 2.60.

The nuclear magnetic resonance hydrogen spectrum is shown in figure 1.

Example 2

This example provides a method for the preparation of compound 54, which is specifically as follows:

raw material A-54 (1.0 eq) (CAS: 2271091-81-5) was dissolved in toluene, raw material D-54 (1.0 eq) (CAS: 2641617-94-7) was dissolved in toluene, then a solution of raw material D-54 was slowly added to the solution of raw material A-54, at N ₂ Pd addition under atmosphere ₂ (dba) ₃ (0.01 eq), X-phos (0.05 eq) and t-Buona (2.0 eq), heating to 90 ℃ and stirring to react for 5h, filtering with diatomaceous earth while hot after the reaction, removing salt and catalyst, cooling the filtrate to room temperature, adding distilled water to the filtrate to wash, separating the liquid to leave an organic phase, extracting the aqueous phase with ethyl acetate, drying the combined organic layers with magnesium sulfate, and removing the solvent with a rotary evaporator. Finally, the remaining material was purified by column chromatography using a mixture of dichloromethane and petroleum ether as eluent to give intermediate 3 (yield: 90.7%).

Intermediate 3 (1.0 eq) was dissolved in toluene, starting material E-54 (1.0 eq) (CAS: 1092408-22-4) was dissolved in toluene, then the solution of starting material E-54 was slowly added to the solution of intermediate 3, at N ₂ Pd addition under atmosphere ₂ (dba) ₃ （0.01eq）、P(t-Bu) ₃ (0.05 eq) and t-BuONa (2.0 eq), heating to 90 ℃ and stirring for reaction for 5h, filtering with diatomaceous earth while hot after the reaction is finished, removing salt and catalyst, cooling the filtrate to room temperature, adding distilled water to the filtrate for washing, separating the liquid to leave an organic phase, extracting the aqueous phase with ethyl acetate, then drying the combined organic layers with magnesium sulfate, and removing the solvent with a rotary evaporator. Finally, the remaining material was purified by column chromatography using a mixture of dichloromethane and petroleum ether as eluent to give compound-54 (yield: 91.3%).

The resulting compound 54 was characterized as follows:

HPLC purity: > 99.7%.

Mass spectrometry test: theoretical value 663.82; the test value was 663.99.

Elemental analysis:

theoretical value: c, 90.47, H, 5.01, N, 2.11, O, 2.41;

test value: c, 90.18, H, 5.23, N, 2.30, O, 2.59.

The nuclear magnetic resonance hydrogen spectrum is shown in figure 2.

Example 3

This example provides a process for the preparation of compound 181, specifically as follows:

dissolving raw material A-181 (1.0 eq) (CAS: 1647008-46-5) in toluene, dissolving raw material B-181 (1.0 eq) in toluene, slowly adding the solution of raw material B-181 into the solution of raw material A-181, and adding the solution of raw material A-181 into N ₂ Pd addition under atmosphere ₂ (dba) ₃ (0.01 eq), X-phos (0.05 eq) and t-Buona (2.0 eq), heating to 95 ℃ and stirring to react for 4h, filtering with diatomaceous earth while hot after the reaction, removing salt and catalyst, cooling the filtrate to room temperature, adding distilled water to the filtrate to wash, separating the liquid to leave an organic phase, extracting the aqueous phase with ethyl acetate, drying the combined organic layers with magnesium sulfate, and removing the solvent with a rotary evaporator. Finally, the remaining material was purified by column chromatography using a mixture of dichloromethane and petroleum ether as eluent to give intermediate 1 (yield: 88.3%).

Dissolving the intermediate 1 (1.0 eq) in a mixed solution of toluene, ethanol and water (the volume ratio of toluene, ethanol and water is 3:1:1), dissolving the raw material C-181 (1.0 eq) (CAS: 589-87-7) in a mixed solution of toluene, ethanol and water (the volume ratio of toluene, ethanol and water is 3:1:1), slowly adding the solution of the raw material C-181 into the solution of the intermediate 1, adding the palladium tetraphenylphosphine (0.01 eq) and the potassium carbonate (2.0 eq) under the protection of nitrogen, stirring uniformly, heating to 80 ℃, refluxing and reacting for 5 hours, and after the solution is cooled to room temperature, retaining an organic phase, and extracting the water phase with ethyl acetate; after the organic phases were combined, drying was performed using anhydrous magnesium sulfate, and the solvent was removed using a rotary evaporator to obtain a solid organic matter. The solid organic matter is completely dissolved by using methylene dichloride, then the solution is slowly dripped into petroleum ether solution, the solution is stirred uniformly, precipitation is separated out, the solid is obtained by suction filtration, absolute ethyl alcohol and petroleum ether are used for leaching in sequence, and the intermediate 2 is prepared after drying (yield: 68.4%).

Intermediate 2 (1.0 eq) was dissolved in toluene, starting material D-181 (1.0 eq) was dissolved in toluene, then the solution of starting material D-181 was slowly added to the solution of intermediate 2, at N ₂ Pd addition under atmosphere ₂ (dba) ₃ （0.01eq）、P(t-Bu) ₃ (0.05 eq) and t-BuONa (2.0 eq), heating to 90 ℃ and stirring for reaction for 6h, filtering with diatomaceous earth while hot after the reaction is finished, removing salt and catalyst, cooling the filtrate to room temperature, adding distilled water to the filtrate for washing, separating the liquid to leave an organic phase, extracting the aqueous phase with ethyl acetate, then drying the combined organic layers with magnesium sulfate, and removing the solvent with a rotary evaporator. Finally, the remaining material was purified by column chromatography using a mixture of dichloromethane and petroleum ether as eluent to give intermediate 3 (yield: 90.1%).

Intermediate 3 (1.0 eq) was dissolved in toluene, starting material E-181 (1.0 eq) was dissolved in toluene, then the solution of starting material E-181 was slowly added to the solution of intermediate 3, at N ₂ Pd addition under atmosphere ₂ (dba) ₃ （0.01eq）、P(t-Bu) ₃ (0.05 eq) and t-BuONa (2.0 eq), heating to 90 ℃ and stirring for reaction for 6h, filtering with diatomaceous earth while hot after the reaction is finished, removing salt and catalyst, cooling the filtrate to room temperature, adding distilled water to the filtrate for washing, separating the liquid to leave an organic phase, extracting the aqueous phase with ethyl acetate, then drying the combined organic layers with magnesium sulfate, and removing the solvent with a rotary evaporator. Finally, the remaining material was purified by column chromatography using a mixture of dichloromethane and petroleum ether as eluent to give compound-181 (yield: 91.6%).

Characterization of the resulting compound 181 is shown in fig. 2:

HPLC purity: > 99.8%.

Mass spectrometry test: theoretical value 739.92; the test value was 740.13.

Elemental analysis:

theoretical value: c, 90.90, H, 5.04, N, 1.89, O, 2.16;

test value: c, 90.71, H, 5.22, N, 2.05, O, 2.34.

The nuclear magnetic resonance hydrogen spectrum is shown in figure 3.

Example 4-example 43

Since the general structural formula is shown as a chemical formula I in the summary, the synthetic route and principle of other compounds are the same as those of the above-listed examples, and therefore, the compounds are not exhaustive. According to the preparation method, the luminescent auxiliary materials shown in the following table 1 can be obtained in the embodiments 4-43:

table 1: mass spectrum and molecular formula are shown in the table below.

The inventor finds that the compound is beneficial to reducing molecular aggregation and accumulation and reducing the blocking problem in evaporation when being used for preparing an organic material layer, and meanwhile, the interaction among molecules is weakened, so that the evaporation temperature of the compound can be reduced, and the change of the chemical structure of a material caused by long-time heating is avoided; the service life, the luminous efficiency and the driving voltage of the OLED device can be improved to a certain extent.

Device example 1

The preparation of the organic electroluminescent device containing the luminescent auxiliary material specifically comprises the following steps:

a. ITO anode: washing an ITO (indium tin oxide) -Ag-ITO (indium tin oxide) glass substrate with the coating thickness of 150nm in distilled water for 2 times, washing by ultrasonic waves for 30min, repeatedly washing by distilled water for 2 times, washing by ultrasonic waves for 10min, transferring into a spin dryer for spin drying after washing, baking for 2 hours at 220 ℃ by a vacuum oven, and cooling after baking is finished, so that the glass substrate can be used. Using the substrate as an anode, and using an evaporator to perform an evaporation device process, and evaporating other functional layers on the substrate in sequence;

b. HIL (hole injection layer): vacuum evaporating the hole injection layer materials HT-1 and P-dock at an evaporation rate of 1 Å/s, wherein the chemical formulas are shown as follows; wherein, the evaporation rate ratio of HT-1 to P-dock is 97:3, the thickness is 10nm;

c. HTL (hole transport layer): vacuum evaporating 120nm HT-1 on the hole injection layer as a hole transport layer at an evaporation rate of 1.5 Å/s;

d. light-emitting auxiliary layer: vacuum-evaporating the compound 1 provided in example 1 as a light-emitting auxiliary layer over the hole transport layer at an evaporation rate of 1 Å/s for 10nm;

e. EML (light emitting layer): then, on the above-mentioned light-emitting auxiliary layer, a Host material (Host) and a Dopant material (Dopant) having a thickness of 20nm were vacuum-evaporated as light-emitting layers at an evaporation rate of 1 Å/s, the chemical formulas of Host and Dopant being as follows; the evaporation rate ratio of Host to Dopant is 98:2;

f. HB (hole blocking layer): vacuum evaporating HB-1 with thickness of 5.0nm at an evaporation rate of 0.5 Å/s;

g. ETL (electron transport layer): the ET and Liq with the thickness of 35nm are vacuum evaporated to be used as electron transport layers at the evaporation rate of 1 Å/s, and the chemical formula of the ET is shown as follows; wherein, the evaporation rate ratio of ET to Liq is 50:50;

h. EIL (electron injection layer): evaporating Yb film layer 1.0nm at an evaporation rate of 0.5 Å/s to form an electron injection layer;

i. and (3) cathode: evaporating magnesium and silver at 18nm at an evaporation rate ratio of 1 Å/s, wherein the evaporation rate ratio is 1:9, so as to obtain an OLED device;

j. light extraction layer: CPL with the thickness of 70nm is vacuum deposited on the cathode at the vapor deposition rate of 1 Å/s to be used as a light extraction layer;

k. packaging the substrate subjected to evaporation: firstly, a gluing device is adopted to carry out a coating process on a cleaned cover plate by UV glue, then the coated cover plate is moved to a lamination working section, a substrate subjected to vapor deposition is placed at the upper end of the cover plate, and finally the substrate and the cover plate are bonded under the action of a bonding device, and meanwhile, the UV glue is cured by illumination.

Referring to the method provided in the above device example 1, compounds 3, 7, 8, 9, 16, 18, 19, 31, 33, 34, 36, 39, 43, 49, 51, 52, 53, 54, 63, 66, 69, 75, 80, 83, 91, 93, 96, 99, 103, 104, 109, 111, 117, 130, 131, 145, 150, 163, 165, 181, 182, 183 were selected respectively instead of the compound 1, evaporation of the light-emitting auxiliary layer was performed, and corresponding organic electroluminescent devices, which were respectively denoted as device examples 2 to 43, were prepared.

Device comparative examples 1-11:

this comparative example provides an organic electroluminescent device whose fabrication method is unique from that of device example 1 in that the organic electroluminescent device was vapor-deposited using the existing comparative compound a, b, c, d, e, f, g, h, i, j, k instead of the light-emitting auxiliary material (compound 1) in device example 1 described above, respectively, to fabricate device comparative examples 1 to 11. Wherein, the chemical structural formula of the comparative compound a, b, c, d, e, f, g, h, i, j, k is as follows:

the organic electroluminescent devices obtained in the above device examples 1 to 43 and device comparative examples 1 to 11 were characterized in terms of driving voltage, luminous efficiency, BI value and lifetime at a luminance of 1000 (nits). The test results are shown in Table 2.

TABLE 2 luminescence property test results (brightness value 1000 nits)

Note that: in the blue top emission device, the current efficiency is greatly affected by chromaticity, and thus, the ratio of the luminous efficiency to CIEy is defined as a BI value, i.e., bi= (cd/a)/CIEy, taking into consideration the factor of chromaticity on efficiency.

As can be seen from table 2, the organic electroluminescent devices prepared using the light-emitting auxiliary materials provided by the present invention were improved in BI value and lifetime while reducing the driving voltage, compared to the conventional organic electroluminescent devices provided by comparative examples 1 to 11.

In the above-described embodiment, compound 165 and compound b; compounds 34, 49, 51 and compounds d, e; compound 117 and compound c; compound 43 and compound g; compound 75 and compound i; compound 163 and compound k are parallel comparative examples. The difference in substitution positions of the aryl groups, as well as the difference in attachment positions, leads to differences in the structure of the compounds. As can be seen from the above device data, the compound having a folded structure has a low bulk density and a long lifetime.

Meanwhile, in the process of preparing the OLED panel, the evaporation temperature is also one of important parameters, and the molecular weight of the compound and the molecular configuration of the compound have close relations with the evaporation temperature.

Table 3: when the vapor deposition rate of 1 Å/s was reached, the vapor deposition temperatures of each example and comparative example were reached

As can be seen from table 3, the size of the relative molecular mass of the compound affects the vapor deposition temperature of the compound, which is relatively high with respect to the molecular mass. The vapor deposition temperature of the compound of the invention is obviously lower than that of the comparative compound. The molecular weight of the comparison compound is higher than that of the compound of the invention, so that the corresponding evaporation temperature is higher, the material is cracked in the evaporation process, the film forming property of the material is poor, and the comprehensive performance of the device is poor.

In the process of manufacturing the OLED panel, after evaporation of the compound of the invention and the comparative compound for 100 hours, the material state pairs are shown in FIG. 4;

compound dihedral angles and simulated densities were tested and simulated by gaussian software, with the plane circled adjacent to the N atom being selected for simulation calculations. The unordered bulk density of the films was simulated by the NPT method in molecular dynamics and the results are shown in table 4 and fig. 5-1 and fig. 5-2.

TABLE 4 Table 4

As can be seen by comparison, the compounds prepared in the examples of the present invention have a greater dihedral angle relative to the comparative compounds.

This may be due to: the substitution position of the arylamine group influences the spatial distortion degree of the compound, the dihedral angle is increased, the molecular configuration is more distorted, the crystallinity is possibly reduced due to the reduction of intermolecular interaction according to the two distorted planes, the aggregation and accumulation of molecules are reduced, the scorching phenomenon caused by the overhigh evaporation temperature in evaporation is reduced, meanwhile, the intermolecular interaction is weakened, the evaporation temperature of the compound can be reduced, and the change of the chemical structure of a material caused by long-time heating is avoided. On the other hand, the aggregation of molecules is reduced, so that a carrier transmission trap is not easy to form, the migration of holes is facilitated, and the service life and the luminous efficiency of the obtained OLED device are improved.

The description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (3)

1. An organic electroluminescent compound is characterized in that the structural general formula is shown in the formulas 3-12:

2. an organic electroluminescent compound according to claim 1, wherein the organic electroluminescent compound has any one of the following structures:

3. use of an organic electroluminescent compound as claimed in any one of claims 1 to 2 for the preparation of an organic electroluminescent device.

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