HK1206773B - Organic electroluminescent material and organic electroluminescent device - Google Patents

Abstract

The present invention relates to "organic electroluminescent materials and organic electroluminescent devices", which have a structure as described in the following formula (I).The organic electroluminescent device of the present invention uses compounds containing [1,2-c] pyridine groups as electron transport materials,Having high electronic transmission and injection capabilities,Due to its excellent thermal stability and good film-forming properties,While improving the efficiency of organic electroluminescent devices,It also improves the service life of the device;Meanwhile,The organic electroluminescent device of the present invention uses compounds containing [1,2-c] pyridine groups as the host material for phosphorescence,Due to its high triplet energy levels,And it has good electronic transmission performance,Can effectively increase the number of electrons in the luminescent layer,Improve the efficiency of the device.

Description

Organic electroluminescent material and organic electroluminescent device

Technical Field

The invention relates to a novel organic electroluminescent material, which is deposited into a film through vacuum evaporation and transition, is applied to an organic electroluminescent diode as an electron transport material or a phosphorescent main body material, and belongs to the technical field of organic electroluminescent device display.

Background

As a novel display technology, the organic electroluminescent device has the unique advantages of self luminescence, wide viewing angle, low energy consumption, high efficiency, thinness, rich colors, high response speed, wide applicable temperature range, low driving voltage, capability of manufacturing flexible, bendable and transparent display panels, environmental friendliness and the like, so that the organic electroluminescent device technology can be applied to flat panel displays and new generation illumination and can also be used as a novel display technologyBacklight source of LCD. A sandwich type double-layer device is made by Tang et al of Kodak corporation in 1987 by using vacuum thin film evaporation technology and using 8-hydroxyquinoline aluminum (Alq3) as a light-emitting layer and triphenylamine derivative as a hole transport layer, and under the driving voltage of 10V, the luminous brightness reaches 1000cd/m²(Tang C.W., Vanslykes.A.appl.Phys.Lett.1987,51, 913-916). This breakthrough development has attracted extensive attention in the scientific and technological field and the industrial field, and has raised the trend of research and application of organic electroluminescence. Subsequently, in 1989, the invention of the subject-object technology greatly improves the luminous efficiency and the service life of the organic electroluminescent device. In 1998, Forrest et al discovered the electrophosphorescence, broken through the theoretical limit that the quantum efficiency of organic electroluminescence is lower than 25%, and increased to 100% (Baldo M.A., Forrest S.R.Et al, Nature,1998,395, 151-.

A classical three-layer organic electroluminescent device comprises a hole transport layer, a light-emitting layer and an electron transport layer. Wherein the electron transport layer of the device is conventionally Alq₃The material has good film forming property and thermal stability, but the material emits strong green light and low electron mobility, and the industrial application of the material is influenced. Subsequently, some electron transport materials having superior properties, such as 1,3,5-Tris (N-phenylbenzimidazol-2-yl) bezene (tpbi), bathocuproene (bcp), bathopthenantholine (bphen), and the like, are also widely used in organic electroluminescent devices. The existing luminescent material can be divided into two types, namely a fluorescent luminescent material and a phosphorescent luminescent material, and a host-guest doping technology is often adopted.

4,4' -Bis (9-carbazolyl) -biphenyl (CBP) is a phosphorescent host material with high efficiency and high triplet energy level, and when CBP is used as the host material, the triplet energy can be smoothly transferred to the phosphorescent light-emitting material, thereby generating high-efficiency red and green light materials. However, these representative host materials tend to limit their utility due to their thermal stability and the short lifetime of the devices produced.

Although organic electroluminescent devices have been advanced and developed for 20 years and organic materials have been developed, there are few materials that meet the market demand and have good device efficiency and lifetime, and good performance and stability.

Acenaphthenyl [1,2-c ] pyridine (ANP) has 16 pi electrons and is an anti-aromatic polycyclic aromatic hydrocarbon compound, which is formed by connecting two separated conjugated system units of naphthalene and pyridine by a five-membered ring and is called non-interactive polycyclic aromatic hydrocarbon. The invention provides an ANP synthetic example and does not have a wide channel, and ANP and derivatives thereof are not applied to electroluminescent materials, namely, a series of novel compounds are invented on the basis of acenaphthene and [1,2-c ] pyridine and are applied to organic electroluminescent devices.

Disclosure of Invention

The invention aims to provide a high-efficiency novel compound as a synthesis and application of an organic electron transport or phosphorescence host material on a device, and provides a high-performance organic electroluminescent device and a preparation method thereof.

The organic electronic material has a chemical structural formula of a chemical formula (I):

wherein the content of the first and second substances,

R₁-R₃independently represent hydrogen, deuterium atom, halogen, hydroxyl, cyano, nitro, amino, C1-C20 alkyl, C1-C20 alkoxy, C6-C40 aryl containing one or more substituents R or unsubstituted, C6-C40 aryl radical, C3-C40 aryl containing one or more substituents R or unsubstituted hetero atom containing one or more, trialkylsilyl, triarylsilyl, aryl containing one or more substituents R or unsubstitutedUnsubstituted triaryl silicon group containing one or more substituents R or unsubstituted diaryloxyphosphorus group, one or more substituents R or unsubstituted aromatic carbonyl group, one or more substituents R or unsubstituted diarylamine group, wherein the heteroatom is B, O, S, N, Se, and the substituent R is halogen, hydroxyl, cyano, nitro, amine, C1-C4 alkyl, C1-C4 alkoxy;

preferably: r₂、R₃Independently selected from hydrogen, halogen, C1-C8 alkyl, C6-C30 phenyl containing one or more substituents R or unsubstituted phenyl, C10-C30 aromatic condensed ring containing one or more substituents R or unsubstituted phenyl, C6-C20 heteroaryl containing one or more substituents R or unsubstituted five-or six-membered heteroaryl containing one or two heteroatoms, C6-C30 heteroaryl containing one or more substituents R or unsubstituted diarylamine, wherein the substituents R are halogen, cyano, nitro, amino, C1-C4 alkyl, C1-C4 alkoxy, and the heteroatoms are O, S and N.

Preferably: r₂、R₃Independently selected from hydrogen, halogen, C1-C4 alkyl, phenyl containing a substituent R or unsubstituted phenyl, naphthyl containing a substituent R or unsubstituted naphthyl, carbazolyl containing a substituent R or unsubstituted carbazolyl, five-membered or six-membered heteroaryl containing a heteroatom, wherein the substituent R is halogen, amino, C1-C4 alkyl.

And R2 and R3 are hydrogen, C1-C4 alkyl, phenyl, naphthyl, tolyl, thifluzal, furan, pyrrole or pyrazine simultaneously.

Preferably: wherein R is₁Selected from hydrogen, halogen, C1-C8 alkyl, C6-C20 contain one or more substituents R or unsubstituted five-or six-membered heteroaryl containing one or more heteroatoms, C10-C20 contain one or more substituents R or unsubstituted aromatic condensed ring groups, C6-C30 contain one or more substituents R or unsubstituted phenyl, diphenylamino, phenylnaphthylamino, triphenylsilyl, diphenylphosphineoxide, phenylcarbonyl or phenylthio, the substituents R are halogen, cyano, nitro, amino, C1-C4 alkyl, C,C1-C4 alkoxy, and the heteroatom is O, S or N.

Further preferably: wherein R is₁Selected from hydrogen, halogen, C1-C4 alkyl, C10-C20 contain one substituent R or unsubstituted carbazolyl, C10-C20 contain one or more substituents R or unsubstituted fluorenyl, naphthyl and phenyl, C6-C10 contain one or more substituents R or unsubstituted five-membered or six-membered heteroaryl containing one or more heteroatoms, and the substituent R is halogen, amino, C1-C4 alkyl.

The five-membered or six-membered heteroaryl containing one or more heteroatoms is pyrimidinyl, pyridyl, thiazolyl, triazolyl or triazinyl, and the R containing one or more substituents or unsubstituted fluorenyl is 9, 9-dimethylfluorenyl, 9-diphenylfluorenyl, 9-ditolyl fluorenyl or spirofluorenyl.

R2 and R3 are benzene simultaneously, R₁Is phenyl, biphenylyl, naphthyl, carbazolyl, substituted with one substituent R, or R₁Is 9, 9-dimethylfluorenyl, 9-diphenylfluorenyl, 9-ditolylhenylfluorenyl or spirofluorenyl, and the substituent R is halogen, amino, C1-C4 alkyl.

The following list of preferred compounds further illustrates the invention. They should not be construed as limiting the invention in any way.

The preparation method of the organic electroluminescent material comprises the following steps:

(1) preparation of

(2) Then with R₁the-CN is prepared by reacting at the temperature of 250-300 ℃ for 40-50 hours under the protection of nitrogen.

The reaction in the step (2) is that the raw materials are mixed under the protection of nitrogen and are directly heated for reaction.

The reaction in the step (2) is to add solvent diphenyl ether and heat and reflux for 40-50 hours.

The step (2) is followed by a recrystallization purification step: and the recrystallization is carried out by adopting a dichloromethane-acetone mixed solvent for recrystallization and purification.

The method also comprises a silica gel column purification step before recrystallization, and adopts petroleum ether for leaching.

The preparation method of the step (1) comprises the following steps: reacting acenaphthenequinone with acenaphthenequinone under nitrogen and strong alkaline conditionsRefluxing at 70-100 deg.C.

The strong alkaline condition is that potassium hydroxide or sodium hydroxide is added into the solution, and the solvent in the reflux solution is ethanol.

The object compound of the invention is a novel high-efficiency organic electron transport or phosphorescence host material and is used for high-performance organic electroluminescent devices. The organic electroluminescent device comprises a substrate, an anode layer formed on the substrate, and a hole injection layer, a hole transport layer, a luminescent layer, an electron transport layer, an electron injection layer and a cathode anode which are sequentially evaporated on the anode layer.

The light emitting layer may be a fluorescent light emitting layer or a red phosphorescent light emitting layer, respectively.

One embodiment of the organic electroluminescent element of the present invention uses the compound of the present invention as an electron transport material;

in another embodiment of the organic electroluminescent device of the present invention, the above compound is used as a phosphorescent host material, and the guest material is preferably an organic iridium compound and an organic platinum compound;

in the organic electroluminescent device of the present invention, the above compound is used as a phosphorescent host material, and the above compound is used as an electron transport layer.

The organic electroluminescent device adopts the compound containing acenaphthene and [1,2-c ] pyridine group as an electron transport material, has higher electron transport and injection capability, and also improves the service life of the device while improving the efficiency of the organic electroluminescent device due to good thermal stability and good film-forming property; meanwhile, the organic electroluminescent device adopts the compound containing acenaphthene and [1,2-c ] pyridine groups as a phosphorescent main body material, and the organic electroluminescent device not only has higher triplet state energy level, but also has good electron transmission performance, so that the number of electrons in a light-emitting layer can be effectively increased, and the efficiency of the device is improved.

Drawings

Fig. 1 is a view showing the structure of a device of the present invention, where 10 is a glass substrate, 20 is an anode, 30 is a hole injection layer, 40 is a hole transport layer, 50 is a light emitting layer, 60 is an electron transport layer, 70 is an electron injection layer, 80 is a cathode,

FIG. 2 is an ESI-MS plot of compound ANP8,

FIG. 3 is a MALDI-TOF-MS chart of Compound ANP34,

FIG. 4 is an ESI-MS plot of compound ANP64,

FIG. 5 shows compound ANP34¹An H NMR chart of the sample solution,

FIG. 6 shows compound ANP64¹An H NMR chart of the sample solution,

FIG. 7 shows compound ANP64¹³C, a NMR chart of the sample,

fig. 8 is a V-J plot of devices 3 (circles), 4 (triangles), and 5 (squares).

Detailed Description

The present invention will be described in further detail with reference to examples. But should not be construed as limiting the invention in any way.

The starting materials used are all commercially available.

Example 1: synthesis of Compound ANP8

Synthesis of intermediate 3

Acenaphthequinone (84g, 0.46mol),1, 3-diphenylpropanone (72.8g, 0.34mol),600ml ethanol, 56g potassium hydroxide were added to a four-necked flask, stirred, purged with nitrogen, and refluxed for 2 hours. Cool to room temperature, filter, and rinse the filter cake with ethanol 2 times to give 130g of a black solid in 91% yield.

Synthesis of Compound ANP8

Intermediate 3(3.56g,10mmol) and intermediate 4(4.69g,40mmol) were mixed under nitrogen and heated to reflux for 48 hours (external temperature 280 ℃). The resulting brown solution was allowed to cool to give a brown solid which was crystallized from dichloromethane-acetone after passing through a silica gel column using petroleum ether as eluent to give ANP8 as white crystals. 0.23g of product is obtained in 5% yield. Calculated value C of ESI-MS m/s₃₄H₂₃N: 445.18, found value [ M⁺]:446.18. See FIG. 2

Example 2: synthesis of Compound ANP34

Intermediate 3(3.56g,10mmol) and intermediate 6(7.17g,40mmol), 60ml of diphenyl ether, were mixed under nitrogen and heated to reflux for 48 hours (external temperature 280 ℃). The resulting brown solution was allowed to cool to give a brown solid which was crystallized from dichloromethane-acetone after passing through a silica gel column using petroleum ether as eluent to give ANP34 as pale yellow crystals. 1.37g of product are obtained, yield 27%.¹H NMR(400MHz,CDCl₃,): 7.98-7.95 (m,2H), 7.90-7.82 (m,2H), 7.65-7.31 (m,20H), 6.93-6.89 (d, 1H). See fig. 5. Calculated value C of MALDI-TOF-MS m/s₃₉H₂₅N: 507.20, found [ M + H]⁺:508.50. See FIG. 3

Example 3: synthesis of Compound ANP64

Intermediate 3(3.56g,10mmol) and intermediate 8(4.30g, 5mmol, according to Organic&Biomolecular Chemistry,10(24), 4704-; 2012 synthesis), 60ml of diphenyl ether, mixed under nitrogen and heated to reflux for 48 hours (external temperature 280 ℃). The resulting brown solution was allowed to cool to give a brown solid which was crystallized from dichloromethane-acetone to give ANP64 as white crystals. 2.15g of product are obtained, yield 50%.¹H NMR(400MHz,CDCl₃,): 7.98-7.94 (m,2H), 7.87-7.77 (m,2H), 7.67-7.22 (m,18H),6.96(d,1H, J ═ 10Hz),1.23(s, 6H). See fig. 6.¹³C NMR(100MHz,CDCl₃,): 27.8,47.1,119.6120.3,122.6,123.6,124.9,125.3,127.0,127.3,127.4,127.9,128.0,128.1,128.8,129.0,129.5,130.0,130.5,130.9,133.2,134.6. See fig. 7. Calculated value C of ESI-MS m/z₄₂H₂₉N: 547.23, found [ M + H]⁺:548.53. See fig. 4.

Example 4

The organic electroluminescent material of the invention is used for preparing OLED, the device number is 1, and the device structure is shown in figure 1

First, a transparent conductive ITO glass (glass substrate 10 with anode 20) is sequentially passed through: washing with detergent solution, deionized water, ethanol, acetone and deionized water. CF further treated with oxygen plasma for 30 seconds, followed by plasma treatment_xAnd (6) processing.

Then, NPB as a hole injection layer 30 was evaporated on the ITO to a thickness of 75 nm.

Then, TCTA was evaporated to form a hole transport layer 40 having a thickness of 10 nm.

Then, ANP34+ 1% of Compound 1 (structure shown in the following formula) was evaporated onto the hole transport layer to a thickness of 20nm as a light-emitting layer 50.

Then, a compound BPhen with a thickness of 20nm was deposited on the light-emitting layer as an electron transporting layer 60.

Finally, 1nm LiF is evaporated as the electron injection layer 70 and the 100nm Al cathode.

Example 5

Device No. 2, device structure was the same as in example 4 except that compound ANP64 was used instead of compound ANP34, respectively.

Example 6

The organic electroluminescent material of the invention is used for preparing OLED, the device number is 3, and the device structure is shown in figure 1

First, a transparent conductive ITO glass (glass substrate 10 with anode 20) is sequentially passed through: washing with detergent solution, deionized water, ethanol, acetone and deionized water. CF further treated with oxygen plasma for 30 seconds, followed by plasma treatment_xAnd (6) processing.

Then, 2-TNATA was evaporated to a thickness of 60nm over the ITO to form a hole injection layer 30.

Then, NPB was evaporated to form a hole transport layer 40 having a thickness of 10 nm.

Then, MADN with a thickness of 30nm was evaporated on the hole transport layer as the light emitting layer 50.

Then, ANP34 was deposited on the light-emitting layer to a thickness of 30nm as an electron transporting layer 60.

Finally, 1nm LiF is evaporated as the electron injection layer 70 and the 100nm Al cathode.

Example 7

Device No. 4, device structure was the same as in example 6 except that compound ANP34 was replaced with compound ANP64, respectively.

Comparative example 1

Device No. 5A device was constructed according to the method of example 6, wherein the electron transport layer 60 of Compound ANP34 was replaced with Alq₃And (4) replacing.

Compound 1

At 20mA/cm²The device parameter results at current density are given in table one:

as can be seen from Table I, the organic electroluminescent device uses acenaphthylene-containing compound [1,2-c ]]The compounds of the pyridine group also have good device properties as electron transport (devices 1 and 2) or host materials (devices 3 and 4). It can be seen from the V-J plot of FIG. 8 that devices 3 and 4 and comparative device 5 possessed lower driving voltages (at 20 mA/cm)²Device 5 driving voltage at current density of 7.61V), proving to contain acenaphthylene and [1,2-c ]]The pyridine group compound can be used as a host material or an electron transport material of a phosphorescent organic electroluminescent device.

Claims (12)

1. An organic electroluminescent material has a structure as described in the following formula (I),

R₁-R₃independently represented as C6-C40, containing one or more substituents R which are halogen, C1-C4 alkyl, C1-C4 alkoxy, or unsubstituted aryl.

2. The organic electroluminescent material according to claim 1, wherein: r₂、R₃Independently selected from phenyl containing one substituent R or unsubstituted phenyl, naphthyl containing one substituent R or unsubstituted naphthyl.

3. The organic electroluminescent material according to claim 2, wherein: the R is₂、R₃While being benzene, R₁Is phenyl, biphenylyl, naphthyl, or R substituted with one substituent R₁Is 9, 9-dimethylfluorenyl, 9-diphenylfluorenyl, 9-ditolylfluorenyl or spirofluorenyl, and the substituent R is halogen and C1-C4 alkyl.

4. The organic electroluminescent material is the following compounds:

5. the organic electroluminescent material according to claim 4, which is the following compound:

6. a process for the preparation of an organic electroluminescent material as claimed in any one of claims 1 to 5, which comprises the following reaction:

(1) preparation of

(2) Then with R₁the-CN is prepared by reacting at the temperature of 250-300 ℃ for 40-50 hours under the protection of nitrogen.

7. The preparation method according to claim 6, wherein the reaction in the step (2) is that the raw materials are mixed under the protection of nitrogen and directly heated for reaction.

8. The preparation method according to claim 6, wherein the reaction in step (2) is performed by adding diphenyl ether as a solvent and heating and refluxing for 40-50 hours.

9. The preparation method according to claim 6, further comprising a recrystallization purification step after the step (2): and the recrystallization is carried out by adopting a dichloromethane-acetone mixed solvent for recrystallization and purification.

10. The method according to claim 9, further comprising a silica gel column purification step with petroleum ether elution before the recrystallization.

11. The method according to claim 6, wherein the step (1) is carried out by: reacting acenaphthenequinone with acenaphthenequinone under nitrogen and strong alkaline conditionsRefluxing at 70-100 deg.C.

12. The method according to claim 11, wherein the strong alkaline condition is that potassium hydroxide or sodium hydroxide is added to the solution, and the solvent in the refluxing solution is ethanol.