阅读说明：本技术 一种空穴注入材料 (Hole injection material ) 是由 张双 于 2020-05-07 设计创作，主要内容包括：本发明提供了一种空穴注入材料,此空穴注入材料是苯并富瓦烯类化合物,并含有氰基、氟基、三氟甲基等。本发明的技术方案具有良好的交叉超共轭特性,结合氰基以及氟基等强吸电子基团,能够赋予分子较强的还原电位,从而辅助空穴传输层高效地进行空穴的注入。(The invention provides a hole injection material, which is a benzofulvalene compound and contains cyano, fluoro, trifluoromethyl and the like. The technical scheme of the invention has good cross super-conjugation characteristic, and can endow molecules with stronger reduction potential by combining with strong electron-withdrawing groups such as cyano-group, fluorine group and the like, thereby assisting the hole transport layer to efficiently inject holes.)

1. A hole injection material, characterized by a compound having the structure shown in formula I:

wherein R is₁-R₁₈At least one of which contains a cyano group, a fluoro group or a trifluoromethyl group.

2. The hole injection material according to claim 1, wherein: the R is₁-R₁₈Each independently selected from hydrogen, cyano, dicyanoethylene, fluoro, trifluoromethyl or cyano, fluoro, trifluoromethyl substituted alkyl, alkoxy, aryl, heteroaryl, aryloxy.

3. The hole injection material according to claim 2, wherein: the R is₁-R₁₈Selected from fluorineA group or a trifluoromethyl group.

4. The hole injection material according to claim 2, wherein: the R is₁-R₁₈Each independently selected from fluoro or trifluoroethyl.

5. The hole injection material according to claim 2, wherein: the R is₁-R₁₈Each independently selected from fluoro or cyano.

6. The hole injection material according to claim 5, wherein: a compound having the structure shown in formula I:

7. the hole injection material according to claim 2, wherein: the R is₁-R₁₈Each independently selected from hydrogen or dicyanoethylene.

8. The hole injection material according to claim 7, wherein: a compound having the structure shown in formula I:

9. the hole injection material according to claim 2, wherein: the R is₁-R₁₈Each independently selected from hydrogen or fluorine.

10. The hole injection material according to claim 2, wherein: the R is₁-R₁₈Each independently selected from hydrogen or trifluoromethoxy.

Technical Field

The invention relates to the field of organic electroluminescent devices, in particular to a hole injection material of a benzofulvalene compound.

Background

An Organic Light-Emitting Diode (OLED) is also called an Organic electroluminescent display or an Organic Light-Emitting semiconductor. The OLED display technology has the advantages of self-luminescence, wide viewing angle, almost infinite contrast, low power consumption, extremely high reaction speed and the like.

Energy level matching is crucial for organic electroluminescent devices, and a stack structure of the organic electroluminescent device, such as a classical organic electroluminescent device, includes: a cathode, an electron transport layer, a light emitting layer, a hole transport layer, and an anode.

Generally, ITO (Indium Tin Oxides) is used as an anode, but the work function of the ITO is high, and the difference between the work function and the energy level of most hole transport materials is about 0.4 eV. Therefore, if a hole injection layer is added between the anode and the hole transport layer, on one hand, the injection of charges can be increased, and on the other hand, the overall efficiency and the service life of the device can be improved.

Of course, doping some strong oxidant into the hole transport layer as a hole injection layer is also another way to improve the hole injection efficiency of the organic electroluminescent device. However, the method has requirements on energy levels of the host material and the dopant material, and generally, a HOMO (Highest Occupied Molecular Orbital) energy level of the host material needs to be close to a LUMO (Lowest Unoccupied Molecular Orbital) energy level of the guest material, so that electrons at the HOMO energy level can jump to the LUMO energy level of the dopant, and thus, a free hole is formed in the hole transport layer, and the conductivity of the device is improved. Meanwhile, the doping can bend the interface energy band, and holes can be injected in a tunneling mode. For the selection of the dopant, lewis acid type metal complexes, halogens, allyl and quinones are common, but the metal complexes and halogens are unstable during device processing, and the allyl compounds have more steps and higher cost in synthesis. Accordingly, the present invention provides a novel hole injection material.

Disclosure of Invention

In view of the problems in the prior art, an object of the present invention is to provide a hole injection material having a good cross-over hyperconjugate characteristic, capable of giving a strong reduction potential to a molecule by combining with a strong electron-withdrawing group such as a cyano group and a fluoro group, and assisting a hole transport layer to efficiently perform hole injection.

According to one aspect of the present invention, there is provided a hole injection material, having a compound of the structure shown in formula I:

wherein R is₁-R₁₈At least one of which contains a cyano group, a fluoro group or a trifluoromethyl group.

Preferably: the R is₁-R₁₈Each independently selected from H, cyano, dicyanoethylene, fluoro, trifluoromethyl or cyano, fluoro, trifluoromethyl substituted alkyl, alkoxy, aryl, heteroaryl, aryloxy.

Preferably: the R is₁-R₁₈Selected from fluoro or trifluoromethyl.

Preferably: the R is₁-R₁₈Each independently selected from fluoro or trifluoroethyl.

Preferably: the R is₁-R₁₈Each independently selected from fluoro or cyano.

Preferably: a compound having the structure shown in formula I:

preferably: the R is₁-R₁₈Each independently selected from hydrogen or dicyanoethylene.

Preferably: a compound having the structure shown in formula I:

preferably: the R is₁-R₁₈Each independently selected from hydrogen or fluorine.

Preferably: the R is₁-R₁₈Each independently selected from hydrogen or trifluoromethoxy。

Preferably: a compound having the structure shown in formula I:

the hole injection material has good cross super-conjugation characteristic, and can endow molecules with stronger reduction potential by combining strong electron-withdrawing groups such as cyano, fluoro, trifluoromethyl and the like, thereby assisting a hole transport layer to efficiently inject holes.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying examples. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art.

In an embodiment of the present invention, there is provided a hole injection material in an organic electroluminescent device, the hole injection material having a structure represented by formula I:

wherein R is₁-R₁₈The substituents may be the same or different from each other, and may be cyano, dicyanoethylene, fluoro, trifluoromethyl, or fluoro-, trifluoromethyl-or cyano-substituted alkyl, alkoxy, aryl, heteroaryl, or aryloxy.

The embodiment of the invention has good cross super-conjugation characteristic, and can endow molecules with stronger reduction potential by combining with strong electron-withdrawing groups such as cyano-group, fluorine group and the like, thereby assisting the hole transport layer to carry out hole injection efficiently.

Preferred compounds of the structure shown in formula I are:

the following specific examples describe the invention:

example 1

The preparation equation is as follows:

the method comprises the following steps:

cu powder (1.00g, 15.63mmol), a-1(1.00g, 1.43mmol), a-2(1.00g,2.99mmol) and 10mL of toluene were added to a reaction flask, heated at 130 ℃ under reflux for 72 hours, cooled, toluene removed, dichloromethane was added, washed with water, dried, the crude product was passed through a column, and hexane/ethyl acetate (10:1) was used as an eluent, and finally purified to obtain compound a-3.

The final product was determined to be MS: 701, performing heat treatment on the mixture;

13C-NMR：(1C,115.6),(1C,116.8),(1C,117.6),(3C,119.6),(3C, 120.1),(1C,120.2),(2C,126.3),(1C,133.7)，(1C,134.1),(3C,136.5), (1C,137.1),(3C,137.4),(1C,137.5),(3C,144.5),(3C,145.1),(1C, 146.9)，(1C,147.1)。

example 2

The preparation equation is as follows:

the method comprises the following steps:

cu powder (1.00, 15.63mmol), b-1(1.00g, 2.14mmol), b-2(1.00g,2.75mmol) and 10mL of toluene were added to a reaction flask, heated at 130 ℃ under reflux for 72 hours, cooled, toluene removed, dichloromethane was added, washed with water, dried, the crude product was passed through a column, and hexane/ethyl acetate (10:1) was used as an eluent, and finally purified to obtain compound b-3.

The final product was determined to be MS: 772;

13C-NMR：(1C,82.3),(1C,83.8),(2C,86),(1C,86.9),(1C,94), (2C,94.6),(1C,104),(1C,106.2),(1C,112.4),(10C,116.5),(2C, 117.8),(1C,118.3),(1C,128.0),(2C,126.3),(1C,135.6),(1C,143.1), (1C,144.8),(2C,145.3),(2C,169.5),(2C,169.7),(1C,167.7),(1C, 170.3),(2C,170.4)。

example 3

The preparation equation is as follows:

the method comprises the following steps:

cu powder (1.00, 15.63mmol), c-1(1.00g, 1.08mmol), c-2(1.00g,1.36mmol) and 10mL of toluene were added to a reaction flask, heated at 130 ℃ under reflux for 72 hours, cooled, toluene removed, dichloromethane was added, washed with water, dried, the crude product was passed through a column, and hexane/ethyl acetate (10:1) was used as an eluent, and finally purified to obtain compound c-3.

The final product was determined to be MS: 1558;

13C-NMR:(6C,106.9),(5C,107.0),(3C,107.3),(3C,111.7),(1C, 112.1),(1C,121.2),(1C,121.6),(3C,123.7),(3C,124.6),(2C,126.3), (1C,126.7),(1C,127.9),(1C,129.3),(3C,129.6),(1C,129.7),(3C, 130.2),(1C,130.6),(1C,130.8),(3C,134.5),(1C,134.7),(3C,135), (1C,137.3)。

example 4

The preparation equation is as follows:

the method comprises the following steps:

cu powder (1.00, 15.63mmol), d-1(1.00g, 2.51mmol), d-2(1.00g,2.91mmol) and 10mL of toluene were added to a reaction flask, heated at 130 ℃ under reflux for 72 hours, cooled, toluene removed, dichloromethane added, washed with water, dried, the crude product was passed through a column, and finally purified using hexane/ethyl acetate (10:1) as an eluent to give compound d-3.

The final product was determined to be MS: 682;

13C-NMR:(4C,78.1),(8C,117.2),(1C,123.2),(6C,125.0),(1C, 125.9),(2C,126.3),(1C,126.4),(3C,126.6),(1C,127.0),(1C,128.1), (1C,131.3),(1C,131.7),(3C,133.0),(1C,133.3),(1C,133.5)(3C, 134.2),(4C,134.6)(4C,164.2)。

example 5

The preparation equation is as follows:

the method comprises the following steps:

cu powder (1.00, 15.63mmol), e-1(1.00g, 1.47mmol), e-2(1.00g,2.99mmol) and 10mL of toluene were added to a reaction flask, heated at 130 ℃ under reflux for 72 hours, cooled, toluene removed, dichloromethane added, washed with water, dried, the crude product was passed through a column, and finally purified using hexane/ethyl acetate (10:1) as an eluent to give compound e-3.

The final product was determined to be MS: 958;

13C-NMR:(1C,29.3),(3C,29.4),(4C,115.7),(1C,115.8),(1C, 115.9),(1C,117.0),(1C,118.5),(1C,119.5),(2C,119.6),(1C,120.0), (2C,120.1),(1C,123.1),(1C,123.5),(2C,126.3),(1C,127.0),(1C, 127.9),(2C,136.5),(2C,137.4),(2C,144.5),(2C,145.1),(1C,146.2), (1C,146.4),(2C,146.6),(1C,155.2),(1C,155.8)。

example 6

The preparation equation is as follows:

the method comprises the following steps:

cu powder (1.00, 15.63mmol), f-1(1.00g, 4.06mmol), f-2(1.00g,2.78mmol) and 10mL of toluene were added to a reaction flask, heated at 130 ℃ under reflux for 72 hours, cooled, toluene removed, dichloromethane was added, washed with water, dried, the crude product was passed through a column, and finally purified using hexane/ethyl acetate (10:1) as an eluent to give compound f-3.

The final product was determined to be MS: 546;

13C-NMR:(4C,112.9),(2C,122.3),(1C,125.7),(3C,126.1),(2C, 126.3),(1C,126.7),(1C,126.8),(1C,127.0),(2C,127.3),(1C,127.6), (2C,127.7),(1C,128.0),(1C,128.2),(1C,131.1),(1C,132.3),(1C, 133.5),(1C,133.7),(1C,133.8),(1C,134.3),(2C,135.3),(2C,161.7)。

example 7

The preparation equation is as follows:

the method comprises the following steps:

cu powder (1.00, 15.63mmol), g-1(1.00g, 4.06mmol), g-2(1.00g,1.91mmol) and 10mL of toluene were added to a reaction flask, heated under reflux at 130 ℃ for 72 hours, cooled, toluene removed, dichloromethane was added, washed with water, dried, the crude product was passed through a column, and finally purified using hexane/ethyl acetate (10:1) as an eluent to give g-3.

The final product was determined to be MS: 710;

13C-NMR:(2C,109.4),(1C,125.7),(1C,126.1),(4C,126.2),(2C, 126.3),(1C,126.7),(1C,126.8),(1C,127.0),(2C,127.2),(2C,127.3), (1C,127.6),(1C,128.0),(1C,128.2),(1C,131.1),(1C,132.3),(2C, 132.7),(1C,133.5),(1C,133.7),(5C,133.8),(1C,134.3),(2C,134.8), (2C,136.3),(2C,138.2),(4C,146.8)。

LUMO energy level test method:

the final products of examples 1 to 7 were subjected to a hole injection property test (LUMO level test step: energy gap Eg of the material obtained by a UV-visible tester (Eg 1240/band edge absorption); HOMO level of the material obtained by Ultraviolet Photoelectron Spectroscopy (UPS); LUMO value was calculated from the relationship between HOMO, LUMO and Eg, specifically: LUMO HOMO + Eg), and the test results were as shown in table 1 below:

table 1: EXAMPLES energy levels of the products

Product source	Lumo energy level (eV)
		Example 1	-5.2
Example 2	-5.3
		Example 3	-5.4
Example 4	-5.2
		Example 5	-5.1
Example 6	-4.8
		Example 7	-4.9

As can be seen from the above table, when the benzofulvalene contains a strong electron-withdrawing group, such as a fluorine atom or a cyano group, the hole injection performance of the compound is good, and the stronger the electron withdrawing property is, the better the hole injection performance of the compound is;

it is clear from the comparison of examples 1, 2 and 3 with examples 6 and 7 that the benzofulvalene compound has poor effect, although it still has hole injection property, if it is not a strong electron withdrawing group;

it is understood from the comparison between example 4 and example 6 that the cross-conjugated structure and the strong electron-withdrawing property can impart excellent hole-injecting property to the material;

therefore, the compound with the benzofulvalene structure in the embodiment of the invention has good hole injection property.

In conclusion, the hole injection material of the present invention has good cross-hyperconjugation characteristics, and can give a strong reduction potential to a molecule by combining with a strong electron-withdrawing group such as a cyano group, a fluoro group, etc., thereby assisting a hole transport layer to efficiently inject holes.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.